Overview of neural tube formation

The nervous system develops from the external layer of the zygotic disc called the ectoderm in a process called neurulation. During embryonic development, a longitudinal thickening of the ectoderm, which is called the neural plate, will differentiate into the brain and spinal cord to form the CNS. The neural plate is a trough-shaped differentiation of the ectodermal layer of the embryonic disc. The neural plate is a vertically oriented, topographically flat sheet of cells; its wide end lies rostrally and becomes the brain, whereas the slim end lies caudally and becomes the spinal cord. A midline groove (central or ventricular zone) divides the neural plate into right and left halves (marginal zones). The central zone contains cells, neuroblasts, and glioblasts and the marginal zone contains the processes of cells of the ventricular zone. The edges of the neural plate (neural folds) fold gradually, creating and deepening the neural groove. By the 20th day of gestation, the neural plate is an oblong structure that is wide at its rostral area (future brain) and slim caudally (future spinal cord). On day 21 of gestation, the edges continue to grow dorsally toward each other until they meet, fusing to create a hollow cylinder called the neural tube. Along the site of fusion, cell surface coats consisting of glycoproteins are deposited as a glue to hold the folds in place until more permanent cell-to-cell contacts can be established.

The neural tube closes first in the future cervical region. The closure proceeds rostrally and caudally, like zippering, leaving an opening at the rostral (cranial) end called the anterior neuropore and an opening at the caudal end called the posterior neuropore. The anterior and posterior neuropores close on days 24 and 27 of gestation, respectively ( Fig. 13.1 ).

Neural Tube Formation.

(From Lundy-Ekman L. Neuroscience: Fundamentals for Rehabilitation . 4th ed. Elsevier.)

By day 26, the neural tube differentiates into two concentric circles. The mantle layer (inner wall) contains cell bodies and will become gray matter. The marginal layer (outer wall) contains processes of cells, whose bodies are located in the mantle layer. The marginal layer develops into white matter, consisting of axons and glial cells.

At the junction between the neural plate and remaining ectoderm lies a narrow strip of cells that develop from the ectoderm, called the neural crest, that will generate a variety of adult structures, including most neurons of the peripheral nervous system (PNS). When the neural crest has developed, the neural tube and the neural crest move inside the embryo. The neural crest detaches from the lateral edge of the neural plate and assumes a location anterolateral to the neural tube. The overlying ectoderm is destined to become the epidermal layer of skin and closes over the tube and neural crest.

As the nervous system continues to develop, the rostral end of the neural tube differentiates into a series of vesicles that constitute the major brain regions and the caudal end of the neural tube forms the spinal cord. The neural crest differentiates to form most of the PNS neurons, with the rest arising from nearby ectoderm.

Neural tube defects

It is generally accepted that neural tube defects (NTDs) are caused by the failure of the neural tube to close, although it has also been suggested that a closed tube may reopen in some cases. ^, A variety of defects results from the failure of the neural tube to properly close. Failure of closure of the neural tube may occur at several sites and the clinical types of NTDs differ depending on the site at which closure fails.

The types of NTDs include anencephaly, spina bifida, encephalocele, craniorachischisis, and iniencephaly. The latter two types are rare, but they tend to occur with disproportionate frequency in areas that have a high rate of NTDs, such as northern China. The most dysraphic disorders occur at the location of the anterior or posterior neuropores, resulting in anencephaly, encephalocele, or spina bifida.

Craniorachischisis is the most severe type of NTD in which the neural tube does not fuse. In this condition, either the none of neural tube closes, which leaves the entire spinal cord open, or the tube is partially closed, which leaves the spinal cord partially open. Craniorachischisis comprises 10% of NTDs, in which the entire neural tube remains open from midbrain to low spine.

Iniencephaly is an uncommon but severe form of NTDs with severe defect of the cervical spine. Iniencephaly involves bifid neural arches, with retroflexion of the skull and an extremely short neck. Most cases involve occipital encephalocele. It seems to be more common in females.

Failure of fusion of the cranial end of the neural tube results in a condition known as anencephaly. In this defect, there is minimal development of the brain, including an absence of development of the forebrain. In most cases, the brain stem may be fairly intact, but the cerebellum may be absent. A failure of the anterior neuropore to close results in a failure of development of the surrounding meninges and skull to form over the incomplete brain, leaving the brain and brain stem exposed ( Fig. 13.2 ). Considerable facial abnormalities are commonly seen in these children. This NTD is not compatible with life. Most fetuses with this condition die before or shortly after birth, and almost none survive for more than few days.

(A) Spina bifida in a newborn. ( B and C ) Anencephaly showing absence of the cranial vault.

(From Pathophysiology: The Biologic Basis for Disease in Adults and Children , 6th ed. McCance – Elsevier.)

Failure of the neural tube to close completely at the cranial level results in crania bifidum, a defect in the cranium. An encephalocele is a herniation of intracranial contents through a defect in the cranium. The cystic structure may contain only meninges (meningocele), meninges and brain structures (meningoencephalocele), or meninges, brain structures, and a part of the ventricular system (meningohydroencephalocele) ( Fig. 13.3 ). Encephaloceles may occur anywhere along the center of the skull from the nose to the back of the neck. Encephaloceles are most common in the occipital region, but they may also occur between the forehead and the nose or at the top of the head. Encephalocele can be asymptomatic but can also be fatal, depending on the extent of brain damage.

Encephalocele.

(From Neurologic Rehabilitation: Neuroscience and Neuroplasticity in Physical Therapy Practice , Nichols Larsen – McGraw Hill.)

Defects in the closure of the posterior neuropore cause a range of malformations known collectively as spina bifida ( Fig. 13.4 ). The defect always involves a failure of the vertebral arches at the affected levels to form completely and fuse to cover the spinal cord. In most cases, the malformation is covered with skin, but the site may be marked by unusual pigmentation, hair growth, telangiectases (large superficial capillaries), or a prominent dimple. The defect can be open myeloschisis and is considered the most severe form of spina bifida. Spina bifida is the most common of the NTDs.

Meningomyelocele in an Infant.

(From Neuroscience Fundamentals for Rehabilitation . 4th ed. Lundy-Ekman.)

Incidence

Statistics about the incidence of spina bifida vary considerably in different parts of the world. Spina bifida and anencephaly, the most common forms of NTDs, affect about 300,000 newborns each year worldwide. In the United States, the most recent annual prevalence estimates that 1460 babies are born with spina bifida, and the incidence is currently 2.48 per 10,000, down from approximately 7.23 per 10,000 births from 1974 through 1979 (before the folic acid mandate ). Current worldwide folic acid fortification programs have resulted in a decreased incidence of spina bifida, ^, with annual decreases of 6600 folic acid–preventable spina bifida and anencephaly births reported since 2006. There was a 31% decline in spina bifida prevalence rates in the immediate postfortification period (October 1998 through December 1999 ^, ). Additionally, there was a continued decline in spina bifida prevalence rates from 1999 to 2004 of 10%. Studies have also demonstrated that decline has varied by ethnicity and race from prefortification to optional fortification to mandatory fortification in the United States. ^, Initially after fortification, the largest decline in prevalence was noted in Hispanic and non-Hispanic white races or ethnicities. Despite this initial decline, postfortification prevalence rates remain the highest in infants born to Hispanic mothers and less in infants born to non-Hispanic white and non-Hispanic black mothers. In addition to periconceptual folate supplementation, it is thought that incidence has decreased subsequent to food fortification in several countries, decreased exposure to environmental teratogens, and increased and more accurate prenatal screening for fetal anomalies.

The incidence of spina bifida has declined since the advent of amniocentesis and the use of ultrasonography for prenatal screening. The diagnosis of spina bifida is one of the common indications for birth termination.

Spina bifida is thought to be more common in females than in males, although some studies suggest no real sex difference. A study of the association of race and sex with different neurological levels of myelomeningocele found the proportions of whites and females to be significantly higher in patients with thoracic-level spina bifida. A significant relation has also been noted between social class and spina bifida: the lower the social class, the higher the incidence. ^,

Etiology

A multifactorial genetic inheritance has been proposed as the cause of spina bifida, coupled with environmental factors of which nutrition, including folic acid intake, is key. Genetic factors seem to influence the occurrence of spina bifida. Cytoplasmic factors, polygenic or oligogenic inheritance, chromosomal aberrations, and environmental influences (e.g., teratogens) have all been considered possible causes. ^, Many studies identified an increased risk of NTD-affected pregnancy to be associated with epidemiological findings such as maternal and paternal ages and occupations, maternal reproductive history, including maternal country of birth and country of conception, nutrition, including folic acid and vitamin B12 deficiency, hyperthermia during early pregnancy, hyperglycemia or diabetes or obesity, and maternal use of medications during early pregnancy.

Genetic considerations, such as an Rh blood type, a specific gene type (HLA-B27), an X-linked gene, and variations in the many folate pathway genes have been implicated, but not conclusively. ^, Malformations are attributed to abnormal interactions of several regulating and modifying genes in early fetal development. Disturbance of any of the sequential events of embryonic neurulation produces NTDs, with the phenotype (i.e., spina bifida, anencephaly) varying depending on the region of the neural tube that remains exposed. Environmental factors combined with genetic predisposition appear to trigger the development of spina bifida, although definitive evidence is not available to support this claim.

A family history of spina bifida is one of the strongest risk factors. The chances of having a second affected child are between 1% and 2%, whereas in the general population, the percentage drops to one-fifth of 1%. ^, Although these factors are related to the incidence of spina bifida, the cause of this defect remains in question.

It is generally accepted that inadequate maternal intake of natural folate, or its synthetic form, folic acid, before and during early pregnancy, is associated with an increased risk of spina bifida. ^, Several studies have shown that the failure to consume folic acid supplements or folic acid-containing multivitamins increases the risk of having an affected child by two- to eightfold. The risk of having a child affected by an NTD is indirectly related to both maternal folate and folic acid intake as well as to maternal folate status. Folate is important in nucleic acid synthesis and in the biosynthesis of methionine through the conversion of homocysteine to methionine. Disruptions in folate metabolism can result in increased homocysteine concentrations, which are teratogenic to the neural tube. The precise mechanism underlying the association between NTDs and folate has not been established.

Vitamin B12, which is metabolically related to folate, might also be associated with NTDs. Studies have shown that deficient or inadequate maternal vitamin B ₁₂ status is associated with a significantly increased risk for NTDs.

Environmental conditions such as hyperthermia in the first weeks of pregnancy or dietary factors such as maternal consumption of canned meats, blighted potatoes, or tea have been implicated but not substantiated. ^,

Maternal diabetes is another factor related to the incidence of spina bifida. Women with pregestational diabetes are at increased risk of having a child with spina bifida and other types of birth defects. In these women, the risk of nervous system malformation including spina bifida is two- to tenfold higher than the risk in the general population. The mechanism underlying this teratogenic effect has not been established, but it is clearly related to the degree of maternal metabolic control.

Other factors associated with NTDs include maternal exposure to anticonvulsant drugs during early pregnancy. Many anticonvulsant drugs such as valproic acid are known teratogens. An increased risk of spina bifida is associated with exposure to valproic acid or carbamazepine alone, or in combination with each other or other anticonvulsants. ^, This risk is increased for women who are taking more than one anticonvulsant.

Women who use these drugs for indications other than epilepsy (e.g., bipolar disease, migraine, chronic pain) are also at higher risk of having a child with spina bifida if they become pregnant while taking these drugs. ^{, ,} The mechanism by which valproic acid and carbamazepine increase the risk of spina bifida has not been established.

Prevention

Historically, nutritional deficiencies, such as of folic acid and vitamin A, have been implicated as a cause of primary NTDs. Fifty to 70% of NTDs can be prevented if a woman of childbearing age consumes sufficient folic acid daily before conception and throughout the first trimester of pregnancy. As a result of research findings in support of folic acid implementation, the US Public Health Service has mandated folic acid fortification since 1998 as a public health strategy. Prenatal vitamins, especially folic acid, are recommended to discourage the condition’s development. Current fortification programs are preventing about 22,000 cases, or 9% of the estimated folic acid–preventable spina bifida and anencephaly cases. At this time, folic acid supplementation and fortification provide the only means of primary prevention for spina bifida and other NTDs.

Economic impact

Health care use and costs for children with spina bifida are significantly greater than those of unaffected children. The lifetime cost to society per affected person with spina bifida is estimated to be over $600,000. One-third of this amount comprises direct medical costs with the remainder being indirect costs, including special educational and care-giver needs and the loss of employment potential. In addition to medical management costs per child, there are additional costs that affect both the family and society across the life-span and are variable and often related to differential market forces and social welfare policies.

A study published in 2012 that examined the associated costs during the first year of life among children with spina bifida indicated that the estimated hospital cost per infant is $39,059 and the total medical expenditures during the first year is more than $50,000. The majority of expenditures during infancy were from inpatient admissions secondary to surgeries concentrated during this time period for those with spina bifida. After infancy, average medical care expenditures during 2003 ranged from $15,000 to $16,000 per year among different age groups of persons with spina bifida. Incremental expenditures associated with medical care were not stable, but decreased with increasing age, from $14,000 per year for children to $10,000 per year for adults aged 45 to 64 years. These data were published in 2007 and reflect costs collected during 2002–2003. With a dynamic economy, it is likely that these values underestimate the cost to society today. Infants born with spina bifida who developed hydrocephalus had Medicaid health care expenditures 2.6 times higher than infants born with spina bifida who did not develop hydrocephalus.

A study examining hospitalizations during the first year of life among children with spina bifida reported that the average number of hospitalizations per infant is 2.4, while the average total days of hospitalization is 25.2, and approximately 18% of the infants were hospitalized more than three times during the first year of life.

Weakness and paralysis

Determining the extent of neurological impairment is not as straightforward as assumed and requires thorough and careful examination and evaluation of the infant. At birth, two main types of motor dysfunction in the lower extremities have been identified. The first type involves a complete loss of function below the level of the lesion, resulting in a flaccid paralysis, loss of sensation, and absent reflexes. The extent of involvement can be determined by comparing the level of the lesion with a chart delineating the segmental innervation of the lower limb muscles and the examination findings. Orthopedic deformities may result from the unopposed action of muscles above the level of the lesion. This unopposed pull may lead to hip flexion, knee extension, and ankle dorsiflexion contractures, depending on the level of the lesion.

When the spinal cord remains intact below the level of the lesion, the effect is an area of flaccid paralysis immediately below the lesion and possible hyperactive spinal reflexes distal to that area. This condition is quite similar to the neurological state of the severed cord seen in traumatic injury. This second type of neurological involvement again results in orthopedic deformities, depending on the level of the lesion, the spasticity present, and the muscle groups involved.

Muscle tone abnormalities

Abnormality in muscle tone is a common feature observed in children with spina bifida. In these children, muscle tone can range from flaccidity to normal tone to spasticity. A mixture of spasticity and hypotonia may be observed in some children with spina bifida. Normal muscle tone has been reported in a small number of children with spina bifida. The majority of children with spina bifida will have lower motor neuron lesions. Children with lower level spina bifida present with signs and symptoms of lower motor neuron lesions including areflexia, hyporeflexia, flaccidity, or hypotonia. Children with higher level spina bifida present with signs and symptoms of upper motor neuron (UMN) lesions including spasticity. Children with Chiari II malformation, hydrocephalus, tethered cord syndrome (TCS), or cervical hydromyelia may present with spasticity, which has also been reported to occur in the upper extremities of many children with shunting. The relationship between muscle tone and function is not clearly understood and is controversial. Problems related to spasticity may include the potential for contractures, difficulty maintaining or changing positions, and the presence of exaggerated primitive reflexes. Difficulties associated with flaccidity may include inability to generate muscle force, inability to bear weight on the flaccid limb, deformities, poor limb posture, and other secondary disorders such as decreased bone strength. Determining the type of muscle tone abnormality and severity may help in decision making regarding treatment, such as braces, and teaching compensatory strategies for functional skills.

Sensory impairment

Children with spina bifida have impaired sensation below the level of the lesion. The sensory loss often does not match exactly the lesion and radiological levels and needs to be carefully assessed. Sensory loss includes pain, temperature, kinesthetic, proprioceptive, and somatosensory information. Sensory deficits manifest in several ways. The child may be hyposensitive or not sensitive to sensory input, startling or withdrawing from light touch or painful stimuli. Because of sensory deficits, children will often have to rely heavily on vision and other sensory systems to substitute for this loss.

Sensory loss (level) correlates with outcomes in terms of mobility, continence, major complications, and overall disability as well as with deaths caused by renal failure. Sensory deficits may produce serious functional consequences. Impairment in sensation may result in significant motor deficits such as impaired balance and coordination. Sensory deficits can compromise safety and make the child vulnerable to injury if their response to painful or damaging stimuli is impaired. It is important that the child and parents be aware of these deficits and of possible ways to compensate or substitute for them, such as relying on vision. Sensory deficits should be considered when creating awareness about safety and prevention of associated disorders such as skin breakdown and pressure ulcers.

Chiari malformation

Chiari II, also known as Arnold-Chiari II malformation, is a common presentation in children with myelomeningocele, with a 99% chance of having an associated Chiari II ( Fig. 13.6 ). This malformation is a congenital anomaly of the hindbrain that arises in the fifth week of gestation as a consequence of abnormal neurulation. This complex anomaly involves downward displacement of the cerebellum and herniation of the medulla, and at times the pons, fourth ventricle, and inferior aspect of the cerebellum, through the foramen magnum into the upper cervical canal. The herniation usually occurs between C1 and C4, but may extend down to T1. ^{, ,} In those with Chiari II malformations and spina bifida, there is a significant reduction in cerebellar volume while, within the cerebellum, the anterior lobe is enlarged and the posterior lobe is reduced. Cardinal features of the Chiari II malformation include myelomeningocele in the thoracolumbar spine, venting of the intracranial CSF through the central canal, dysgenesis of the corpus callosum, hypoplasia of the posterior fossa, herniation of the hindbrain into the cervical spinal canal, and compressive damage to cranial nerves. The abnormal configuration of the brain in Chiari II malformation often results in hydrocephalus, a blockage of the normal flow of the CSF in the ventricular system. Hydromyelia and syringomyelia are seen in patients with Chiari II malformation ( Fig. 13.7 ).

Myelomeningocele and Arnold-Chiari II Malformation.

(From Neurologic Rehabilitation: Neuroscience and Neuroplasticity in Physical Therapy Practice , Nichols-Larsen – McGraw Hill.)

(A) Normal Brain with Patent cerebrospinal fluid (CSF). (B) Arnold-Chiari malformation type II with enlarged ventricles.

(From Pathology: Implications for the Physical Therapist . 4th ed. Goodman, Elsevier.)

Not all Chiari II malformations are symptomatic. The severity can vary dramatically, and signs and symptoms can vary from no symptoms to severe, potentially debilitating, or life-threatening symptoms. Chiari II malformations may present with a spectrum of signs and symptoms related to brain stem compression and lower cranial nerve dysfunction. As a result of a symptomatic Chiari II malformation, problems with respiratory and bulbar function may be evident in a child with spina bifida. Paralysis of the vocal cords occurs in a small percentage of patients and is associated with respiratory stridor. Apneic episodes also may be evident, although their direct cause remains in question. Children with spina bifida may also exhibit difficulty in swallowing and have an abnormal gag reflex. Problems with aspiration, weakness and cry, and upper-extremity weakness may also be present in children with a symptomatic Chiari II malformation. ^, Thus depending on the orthopedic deformities present and the neurological involvement, severe respiratory involvement is possible in the affected child. These symptoms may be caused by significant compression of the hindbrain structures or dysplasia of posterior fossa contents, which can also occur in patients with Chiari II malformation. ^, This complex hindbrain malformation is a common cause of death in children with myelomeningocele, despite surgical intervention and aggressive medical management.

Occipital headaches felt near the base of the skull radiating to the neck and shoulders are a common symptom in older children, which can be brought on or worsened by coughing, straining, or sneezing. Signs and symptoms may include abnormalities affecting the eyes, including blurred vision, double vision, abnormal sensitivity to light, nystagmus, and pain behind the eyes. Vertigo, dizziness, ringing in the ears (tinnitus), and bilateral hearing impairments can also develop. Additional symptoms associated with a Chiari malformation may include muscle weakness, balance deficits, poor coordination and paresthesia, and tingling or burning sensations in the fingers, toes, or lips.

Some children never require treatment for a Chiari malformation. Severe brain stem Chiari II malformation may be reversed after repair and lower rates of hydrocephalus are noted after fetal closure.

Association pathways

Diffusion tensor tractography studies of association pathways in children with spina bifida have revealed characteristics of abnormal development, impairment in myelination, and abnormalities in intrinsic axonal characteristics and extraaxonal or extracellular space. An imaging study in children with spina bifida indicated that there is a pattern of thinning associated with hydrocephalus with an overall reduction in white matter and increased neocortical thickness in the frontal regions, suggesting long-term disruption of brain development in children with spina bifida that extends far beyond the NTD in the first weeks of gestation. Other studies indicated changes or abnormalities in the tectum. These changes in diffusion metrics observed in children with spina bifida are suggestive of abnormal white matter development and persistent degeneration with increased age.

Tethered cord

Tethered spinal cord is defined as a pathological fixation of the spinal cord in an abnormal caudal location ( Figs. 13.8 and 13.9 ). This fixation produces mechanical stretch, distortion, and ischemia with daily activities, growth, and development. Ischemic injury from traction of the conus directly correlates with degree of oxidative metabolism and degree of neurological compromise. In addition to ischemic injury, traction of the conus by the filum may also mechanically alter the neuronal membranes, resulting in altered electrical activity. The abnormal attachments cause an abnormal stretching of the spinal cord that limits its movement within the spinal column and may cause strain on the spinal cord during normal movements. This abnormal attachment is associated with progressive stretching and increased tension of the spinal cord as a child ages, potentially resulting in a variety of symptoms. The progression of neurological signs and symptoms is highly variable due to variation in growth rate of the spinal cord and the spinal column. In some individuals, symptoms can develop at birth, infancy, or early childhood (EC). Some patients may not develop symptoms until adulthood. The most commonly reported triggers in adult patients with repaired SB myelomeningocele are falls, back trauma, heavy lifting, and vaginal childbirth. The presence of TCS should be suspected in any patient with abnormal neurulation (including patients with myelomeningocele, lipomeningocele, dermal sinus, diastematomyelia, myelocystocele, tight filum terminale, and lumbosacral agenesis).

Tethered Cord in Myelodysplasia.

(From Staheli LT. Practice of Pediatric Orthopedics. Philadelphia: Lippincott Williams & Wilkins; 2001.)

Magnetic resonance image showing a tethered spinal cord at L3.

(From Lundy-Ekman L. Neuroscience: Fundamentals for Rehabilitation . 4th ed. Elsevier.)

The specific symptoms, severity, and progression vary from one individual to another. Presenting symptoms may include decreased strength (often asymmetrical), development of lower-extremity spasticity, back pain at the site of sac closure, early development or an increasing degree of scoliosis (especially in the low lumbar or sacral level ), or a change in urological function. ^{, ,} Ten to 30% of children will develop TCS after repair of a myelomeningocele. Essentially all children with a repaired myelomeningocele will have a tethered spinal cord, as demonstrated on MRI. Diagnosis of TCS is made based on clinical criteria. The six common clinical presentations of TCS are increased weakness (55%), worsening gait (54%), scoliosis (51%), pain (32%), orthopedic deformity (11%), and urological dysfunction (6%). This clinical spectrum may be primarily associated with these dysraphic lesions or may be caused by spinal surgical procedures. The cord may be tethered by scar tissue or by an inclusion epidermoid or lipoma at the repair site. In individuals with no or minimal symptoms, surgery may not be indicated, and the symptoms should be monitored for progression. Surgery soon after symptoms emerge appears to improve chances for recovery and can prevent further functional decline. Surgery is recommended to prevent or reverse progressive neurological symptoms. The primary goal of surgery is to detach the spinal cord where it is adherent to the thecal sac, relieving the stretch on the terminal portion of the cord. Surgery to untether the spinal cord (tethered cord release [TCR]) is performed to prevent further loss of muscle function, decrease the spasticity, help control the scoliosis, ^, or relieve back pain. ^,

The responses to treatment for TCS vary from one person to another. The effectiveness of a TCR may be demonstrated by an increase in muscle function, relief of back pain, and stabilization or reversal of scoliosis. ^{, ,} It has been reported that scoliosis response to untethering and progression of scoliosis after untethering vary with the location of tethering, ^, as well as Risser grade and Cobb angle. Those with Risser grades 3 to 5 and Cobb angle less than 40 degrees are less likely to experience curve progression after untethering. Those with Risser grades 0 to 2 and Cobb angle greater than 40 degrees are at a higher risk of recurrence. ^, Spasticity, however, is not always alleviated in all patients. Selective posterior rhizotomy has been advocated for patients whose persistent or progressive spastic status after tethered cord repair continues to interfere with their mobility and functional independence. ^,

Orthopedic deformities

There are both congenital and acquired orthopedic deformities seen in patients with spina bifida. The orthopedic problems that occur with myelomeningocele may be the result of (1) the imbalance between muscle groups; (2) the effects of posture, positioning, and gravity; and (3) associated congenital malformations. Decreased sensation and neurological complications also may lead to orthopedic abnormalities.

Besides the malformation of vertebrae at the site of the lesion, various spinal deformities may be present including hemivertebrae; deformities of other vertebral bodies and their corresponding ribs may also be present. ^, Lumbar kyphosis may be present as a result of the original deformity (congenital). In addition, as a result of the bifid vertebral bodies, the misaligned pull of the extensor muscles surrounding the deformity, as well as the unopposed flexor muscles, contributes further to the lumbar kyphosis. As the child grows, the weight of the trunk in the upright position may also be a contributing factor. Scoliosis may be present at birth because of vertebral abnormalities or may become evident as the child grows older. The incidence of scoliosis is lower in low lumbar or sacral level deformities. ^, Scoliosis may also be neurogenic, secondary to weakness or asymmetrical spasticity of paraspinal muscles, TCS, or hydromyelia. Lordosis or lordoscoliosis is often found in the adolescent and is usually associated with hip flexion deformities and a large spinal defect. ^, Many of these trunk and postural deformities exist at birth but are exacerbated by the effects of gravity as the child grows. They can compromise vital functions (cardiac and respiratory) and should therefore be closely monitored by the therapist and family.

The type and extent of deformity in the lower extremities depend on the muscles that are active or inactive. In total flaccid paralysis, in utero deformities may be present at birth, resulting from passive positioning within the womb. Talipes equinovarus (clubfoot) and vertical talus (which produces a “rocker-bottom” deformity) are two of the most common foot abnormalities. Knee flexion and extension contractures also may be present at birth. Other common deformities are hip flexion, adduction, and internal rotation, usually leading to a subluxed or dislocated hip. Although many of these problems may be present at birth, preventing positional deformity (such as the frog-leg position), which may result from improper positioning of flaccid extremities, is of the utmost importance. Orthopedic care varies throughout the course of the child’s life. One of the main goals of orthopedic care of a patient with spina bifida is to correct deformities that may prevent the patient from using orthoses to ambulate in childhood. Additionally, monitoring of spinal balance and the status of the hips is required. Changes in clinical orthopedic management have evolved to establish evidence-based interventions.

Osteoporosis

Osteoporosis and osteopenia are often present in patients with spina bifida mostly related to the limited opportunities for weight bearing and upright mobility. The higher the level of neurological involvement, the greater the risk. Early mobilization and weight bearing can aid in decreasing osteoporosis. ^, Because the paralyzed limbs of the child with spina bifida have increased amounts of unmineralized osteoid tissue, they are prone to fractures, particularly after periods of immobilization, especially spica casting.

Bowel and bladder dysfunction

Myelomeningocele is likely the most common congenital diagnosis for the development of a neurogenic bladder in children. Because of the usual involvement of the sacral plexus, nearly all patients with myelomeningocele have some degree of neurogenic bladder, and children with spina bifida commonly deal with some form of bowel and bladder dysfunction.

Spinal control of bladder, bowel, and sexual functions originates in the sacral spinal cord levels S2 to S4. When the bladder is empty, efferent sympathetic signals from spinal levels T11 to L1 inhibit contraction of the bladder wall and maintain contraction of the internal sphincter. When the bladder fills, the fullness of the bladder stretches the bladder wall and afferent fibers send signals to the reflex center in the sacral spinal cord about the fullness status. This information is then conveyed to the brain. When the condition is appropriate, the higher brain centers initiate emptying the bladder by sending signals to the urination center in the sacral spinal cord, which send signals to the parasympathetic neurons to stimulate contraction of the bladder wall and relaxation of the internal sphincter. Simultaneously, the pontine center sends signals to the spinal cord to facilitate neurons that inhibit the external sphincter and inhibit pelvic floor muscles. Bowel control is similar to bladder control. Stimulation of stretch receptors in the wall of the rectum stimulates emptying of the bowels by sending signals to the bowel center in the sacral spinal cord, which sends signals to alert the higher brain centers about the fullness status. If appropriate, the higher brain centers send signals to the bowel control centers in the sacral spinal cord to relax the sphincter and empty the bowels.

The level of spinal level lesion determines the type of bladder and bowel dysfunction. Lesions above the sacral spinal cord (the control center of the bladder and bowel) result in UMN bladder or bowel. The lesion interrupts descending efferent signals to the bladder and bowel centers but does not interrupt the sacral level reflexive control of the bladder and bowel. Disruption of the higher center control results in lack of inhibition of the bladder and bowel reflexive action, leading to hyperactive bladder and bowel. In this lesion, the bladder and bowel will not receive the signals from the higher center to empty. Reflexive emptying may occur automatically whenever the bladder and bowel are stretched by a certain volume. In this case, the bladder and bowel often expel or “squirt” small volumes at inconvenient times. The UMNL results in hypertonic, hyperreflexive bladder and bowel with reduced capacity. Failure to store or to empty the bladder with reduced capacity make those individuals prone to kidney damage.

Injuries at the sacral level are considered to be lower motor neuron lesions. This type of lesion results in damage to the reflexive bladder and bowel emptying and flaccid paralysis with the bladder and bowel being hypertonic. In this lesion, the reflexes are absent, so there is no spontaneous emptying of the bladder or bowel. The bladder and bowel are flaccid. Urine or stool will fill the bladder or bowel without emptying. When the bladder or bowel overfill with urine or stool and cannot stretch any further, urine or stool leak or dribble out. This emptying is often incomplete. Individuals will often experience dampness from urine or smearing of stool. The continual filling without emptying leads to an overfilling of the bladder and bowel, which can cause infection.

The effects of bladder and bowel dysfunctions pose a serious medical condition with serious medical complications that require long-term management. Besides various forms of incontinence, incomplete emptying of the bladder remains a constant concern because infection of the urinary tract and possible kidney damage may result. Regulation of bowel evacuation must be established so that neither constipation nor diarrhea occurs. Negative social aspects of incontinence can be minimized by instituting intervention that emphasizes patient and family education and a regular, consistently timed, reflex-triggered bowel evacuation.

Bladder and bowel dysfunctions can have serious health complications, including death. They have negative influences on self-esteem, social activities, and quality of life, imposing significant limitations on a person’s activity and participation in daily activities. Urinary and fecal incontinence forms a major barrier to attending school, obtaining employment, and sustaining relationships.

Cognitive impairment and learning issues

Children with spina bifida have a rather different cognitive profile than typically developing children. ^, Impairments in the cognitive profile is related to both Arnold-Chiari II malformation and hydrocephaly. The Arnold-Chiari II malformation and hydrocephaly affect the development of brain structures of the hindbrain, midbrain, ventricular system, and subcortical gray matter. These deficits lead to impairments in the cognitive domains of executive functioning, visual-spatial working memory, intelligence, language, and learning.

Although children with spina bifida without hydrocephalus may have normal intellectual potential, children with hydrocephalus, particularly those who have shunt infections, are likely to have below-average intelligence. These children often demonstrate learning disabilities and poor academic achievement. Even those with a normal IQ show moderate to severe visual-motor perceptual deficits. The inability to coordinate eye and hand movements affects learning and may interfere with activities of daily living (ADLs), such as buttoning a shirt or opening a lunchbox. Difficulties with spatial relations, body image, and development of hand dominance may also be evident. ^, Children with myelomeningocele demonstrate poorer hand function than age-matched peers. This decreased hand function appears to be caused by cerebellar and cervical cord abnormalities rather than hydrocephalus or a cortical pathological condition.

Prenatal studies have shown that the CNS as a whole is abnormally developed in fetuses with myelomeningocele. The impairment of intellectual and perceptual abilities has been linked to damage to the white matter caused by ventricular enlargement. This damage to association tracts, particularly in the frontal, occipital, and parietal areas, could account for the often severe perceptual-cognitive deficits noted in children with spina bifida. ^, Lesser involvement of the temporal areas may account for the preservation of speech, whereas the semantics of speech, which depends on association areas, is impaired. The “cocktail party speech” of children with spina bifida can be deceptive because they generally use well-constructed sentences and precocious vocabulary. A closer look, however, reveals a repetitive, inappropriate, and often meaningless use of language not associated with higher intellectual functioning. Research on learning difficulties in children with spina bifida and hydrocephalus suggests that many of these children experience difficulties. Tasks and skills affected include memory, reasoning, math, handwriting, organization, problem solving, attention, sensory integration, auditory processing, visual perception, and sequencing.

Integumentary impairment

Growth nutrition and obesity

Children with spina bifida face multiple challenges throughout their life-span. Arnold-Chiari II malformation, hydrocephalus neurogenic bowel, neurogenic bladder, and lack of activities are common associated disorders that have implications for growth and nutrition.

Nutritional intake and weight gain and loss have been found to be problematic in children with myelomeningocele. Early on, infants with spina bifida may have feeding issues as a result of an impaired gag reflex, swallowing difficulties, and a high incidence of aspiration. ^, Altered oral-motor function has been attributed to the Chiari II malformation. These impairments may lead to nutritional issues and delayed growth and weight gain. Speech, physical, and occupational therapists (OTs) working as a team are often needed to address these issues.

Conversely, obesity can be a significant issue for children with spina bifida, particularly when the child gets older and moves into teenage years and adulthood. This problem is complex and multifactorial. Mobility limitations and decreased energy expenditure result in lower physical activity levels. In addition, decreased lower limb mass diminishes the ability to burn calories, which leads to weight gain and makes it challenging for a child to achieve and maintain a healthy weight. Decreased caloric intake as well as a lifelong engagement in rewarding and physically challenging physical activities are necessary to enhance weight control and prevent obesity.

The presence of obesity may put the child at risk for additional associated problems such as high blood pressure, high blood sugars (diabetes), and high cholesterol.

Obesity may limit the child’s ability to walk, transfer, and move, resulting in reduced mobility and decreased physical activity. This can limit the child’s independence in self-care.

Being obese and overweight increases pressure on the skin. This may increase the risk of pressure ulcers for children in wheelchairs. Increased weight increases the amount of pressure on skin in the seating position and thus places the child at more risk for development of pressure ulcers.

Obesity may limit the child’s ability to breathe and expand his chest, thereby increasing the risk for development of deformities, particularly scoliosis, as well as increasing the breathing difficulty associated with scoliosis.

Dysphagia and swallowing

Chiari malformation and hydrocephaly may result in direct pressure upon cranial nuclei or cranial nerves by the herniated cerebellar tonsils and/or cause traction on the cranial nerves as they pass around the herniated tissue to ascend to the neural foramina. This may affect coordination of the muscles involved in sucking, swallowing, and breathing patterns in infants and can result in neurogenic dysphagia. Additionally, hypotonicity and poor sitting posture, along with the Arnold-Chiari II malformation and hydrocephaly, may put infants with spina bifida at a higher risk for feeding issues.

Anthropometrics

Children with myelomeningocele are short in stature. Growth in these children may be influenced by growth-retarding factors as a result of a neurological deficit such as tethered cord. Endocrine disorders and growth hormone deficiency have also been found to contribute to short stature in this population. As a result of complex CNS anomalies (midline defects, hydrocephalus, and Arnold-Chiari malformation), these children are at risk for hypothalamopituitary dysfunction leading to growth hormone deficiency. ^, Treatment with recombinant human growth hormone has proven successful in fostering growth acceleration in these children. ^{, ,}

Obtaining an accurate length/height measurement in children with spina bifida may be challenging secondary to contractures, scoliosis, and body structure differences. In addition to the 2000 Centers for Disease Control and Prevention (CDC) growth charts, spina bifida growth charts may be used in conjunction with the CDC growth charts to evaluate growth in a child with spina bifida. The disease-specific charts include growth data according to lesion level and ambulatory status.

Linear growth usually slows down around 2 years of age, but weight gain may continue trending or increase at a faster rate due to decreased activities. Children with spina bifida have earlier growth spurts and higher rates of precocious puberty; however, their final adult height is shorter in relation to their peers.

The lack of activity and ambulation results in a low level of total energy expenditure and needs, which can make it a challenge for a child to achieve and maintain a healthy weight. Children with spina bifida have been shown to maintain their weight with an energy intake meeting 80% of the Recommended Dietary Allowance (RDA).

Psychosocial and emotional issues

Psychological and social issues in children with spina bifida seem to be affected by deficits in cognitive function and clinical manifestations such as neurological deficits, mobility deficits, and urological disorders. The consequences of the cognitive deficits seem to affect the social life of these individuals. ^, Considering all the clinical manifestations resulting from this congenital neurological defect, social and emotional difficulties will arise for these children and their families. These will be considered appropriate when discussing the stages of recovery and rehabilitation from birth through adolescence.

Prenatal testing and diagnosis

The majority of cases with spina bifida can be diagnosed during pregnancy. Ultrasonography can be used for early detection of spina bifida during pregnancy. A common blood test, maternal serum alpha-fetoprotein (AFP), is offered during the second trimester (16th to 20th week of pregnancy) to screen for NTDs, including spina bifida and anencephaly. Positive findings of AFP in the amniotic fluid or a positive sonography can be followed by detailed sonography or amniocentesis to diagnose spina bifida. The presence of significant levels of AFP in the amniotic fluid has led to the detection of large numbers of affected fetuses, and maternal serum AFP levels have been effective in detecting approximately 80% of NTDs. Prenatal screening can be most effective when a combination of serum levels, amniocentesis or amniography, and ultrasonography is used. Although this screening is not yet performed routinely, it is suggested for those at risk for the defect. Additionally, the fetal karyotype test can be used to identify or rule out chromosomal anomalies.

When a diagnosis of spina bifida confirmed, ultrasonography is used to detect any brain cranial abnormalities including the presence of Chiari II malformation. Ultrasonography can be used to assess spontaneous leg movements, spine and lower extremity deformities, and other physical defects. Prenatal MRI, with ultrafast T2-weighted sequences, can also be used to characterize the Chiari II and other brain malformations.

Prenatal care

NTDs, including spina bifida, are among the common indication for birth termination. Most fetuses with spina bifida that are not electively terminated receive no treatment until after birth.

If it is determined that the unborn baby has a confirmed diagnosis of spina bifida, both fetus and mother should be referred to a high-risk pregnancy specialist for further evaluation and follow up. A series of ultrasounds will be performed throughout pregnancy to monitor the fetus’ progress and detect any other brain anomalies or lower limb deformities. A chromosomal analysis may be recommended to identify chromosomal abnormalities. Other tests, including a fetal MRI, may be recommended to detect cranial abnormalities and other associated disorders such as Chiari II malformation.

Knowledge of the defect allows for preparation for cesarean birth and immediate postnatal care. This includes mobilization of the interdisciplinary team that will continue to care for the child. For parents who decide to carry an involved fetus to term, adjustment to their child’s disability can begin before birth, which includes mobilizing their own support system. Education from an integrated team regarding what will follow after delivery and neurosurgical closure is imperative to aid families in decision making and to allow families to assess and understand the child’s disability and future care options.

Advances in the field of prenatal medicine that affect spina bifida management and outcome include in utero treatment of hydrocephalus and in utero surgical repair to close the myelomeningocele. This challenging surgical procedure is practiced in only a few specialty centers and so far has been shown to offer palliation of the defect, at best. Treatment such as this, in conjunction with prenatal diagnosis, has been shown to have a positive impact on the incidence and severity of complications associated with spina bifida. Limitations of current postnatal treatment strategies and considerations of prenatal treatment options continue to be explored. Ethics, timing of repair, and surgical procedures are all being investigated. In addition, continued assessment of outcomes from those who have undergone presurgical management requires continued exploration. The Management of Myelomeningocele Study (MOMS) was initiated in 2003 as a large randomized clinical trial designed to compare the two approaches to the treatment of infants with spina bifida (prenatal or fetal surgery versus postnatal surgery) to determine if one approach was better than the other. The primary end point of this trial was the need for a shunt at 1 year, and secondary end points included neurological function, cognitive outcome, and maternal morbidity after prenatal repair. Results demonstrated that prenatal surgery significantly reduced the need for shunting and improved mental and motor function at 30 months. Reduced incidence of hindbrain herniation at 12 months and successful ambulation by 30 months were also reported. While prenatal surgery was associated with improved function and reduced need for shunting, maternal and fetal risks, including preterm delivery and uterine dehiscence at delivery, were reported.

Neurosurgical management

The key early priorities in the management of spina bifida are to repair the spinal cord and spinal nerves, to protect the exposed nerves and structures from additional trauma, and to prevent infection from developing in the exposed nerves and tissue through the spinal defect ( Fig. 13.10 ). Timing of the surgical closure and repair is important and may occur prenatally or soon after birth to minimize the risk of neural damage and infection. The aim of either surgery is to replace the nervous tissue into the vertebral canal, cover the spinal defect, and achieve a watertight sac closure. This early management has decreased the possibility of infection and further injury to the exposed neural cord. ^{, ,}

Postsurgical Repair Scarring.

(From Neurologic Rehabilitation: Neuroscience and Neuroplasticity in Physical Therapy Practice , Nichols Larsen – McGraw Hill.)

Fetal surgery may be performed in utero, particularly for the child myelomeningocele, usually during weeks 19 to 25 of pregnancy. Postnatal surgery is usually recommended 24 to 48 hours after birth. Fetal surgery is performed within the uterus and involves opening the mother’s abdomen and uterus and repairing the spinal cord of the fetus. The benefits of fetal surgery include less exposure of the vulnerable spinal nerve tissue to the intrauterine environment, thus reducing the damage to the spinal cord. Additionally, fetal surgery may decrease the risk of fetal hindbrain abnormalities, thus decreasing the severity of certain complications such as Chiari II and hydrocephalus, and in some cases may decrease the possibility of needing treatment for hydrocephalus and shunt implantation. The major risks to the fetus are those that might occur if the surgery stimulates premature delivery, such as brain hemorrhage, organ immaturity, or death. Delivery may need to occur at a high-risk pregnancy center. Cesarean section is the preferred method of deliver to avoid trauma to the spinal sac and minimize the amount of damage to the infant’s exposed spinal nerves that may occur during vaginal delivery. A child born with meningocele or myelomeningocele usually requires care in the neonatal intensive care unit (NICU).

Progressive hydrocephalus may be evident at birth in a small percentage of children born with myelomeningocele. A greater majority, however, have hydrocephalus 5 to 10 days after the back lesion has been closed. ^, With the advent of computed tomography (CT), early diagnosis of hydrocephalus can be made in the newborn without the need for clinical examination.

Although clinical signs are not always definitive, hydrocephalus may be suspected if (1) the fontanels become full, bulging, or tense; (2) the head circumference increases rapidly; (3) a separation of the coronal and sagittal sutures is palpable; (4) the infant’s eyes appear to look downward only, with the cornea prominent over the iris (“sunsetting sign”); and (5) the infant becomes irritable or lethargic and has a high-pitched cry, persistent vomiting, difficult feeding, or seizures ( Table 13.1 ). ^{, ,}

If the results of CT confirm hydrocephalus, a ventricular shunt is indicated to control excessive CSF buildup and further brain damage. This procedure involves diverting the excess CSF from the ventricles to another site for absorption. In general, two types of procedures—the ventriculoatrial (VA) and ventriculoperitoneal (VP) shunt—are currently used, the latter being the most common ( Fig. 13.11 ). The shunt apparatus is constructed from Silastic tubing and consists of three parts: a proximal catheter, a distal catheter, and a one-way valve. As CSF is pumped from the ventricles toward its final destination, backflow is prevented by the valve system. In this manner, intracranial pressure is controlled, CSF is regulated, and hydrocephalus is prevented from causing damage to brain structures. An alternate means of controlling hydrocephalus may be the use of endoscopic third ventriculostomy (EVT). EVT is a procedure that, in selected patients with obstructive hydrocephalus, allows egress of CSF from the ventricles to the subarachnoid space. This can decompress the ventricles and allow normal intracranial pressures and brain growth. This procedure is typically reserved as a last resort.

Ventriculoatrial shunt.

(From Goodman C, Fuller K. Pathology Implications for the Physical Therapist . 4th ed. Elsevier–Saunders; 2014.)

Management strategies in the care of shunted hydrocephalus vary. Shunt complications occur frequently and require an average of two revisions before age 10 years. The most common causes of complications are shunt obstruction and infection. ^, Revising the blocked end of the shunt can clear obstructions. Infections may be handled by external ventricular drainage and courses of antibiotic therapy followed by insertion of a new shunting system. The problem of separation of shunt components has been largely overcome by the use of a one-piece shunting system. The single-piece shunt decreases the complications of shunting procedures. Shunt revision is usually required as the child grows by installing a larger one.

Surgical treatment for hydromyelia usually has good outcomes; it may include treating the underlying cause such as revision of a CSF shunt, posterior cervical decompression, or a central canal to pleural cavity shunt with a flushing device. ^,

Asymptomatic tethered spinal cord will require monitoring for any changes in the clinical signs and symptoms. Conservative treatments such as medications, alternative therapies, rest, and physical therapy may provide temporary relief from pain. The only successful intervention is untethering surgery. Surgery for tethered spinal cord is generally performed if there are clinical signs or symptoms of deterioration such progressive or severe pain, loss of muscle function, deterioration in gait, or changes in bladder or bowel function. The surgery for untethering the cord involves releasing the spinal cord and clearing it from the scarred tissues attached to it. Early surgery on a tethered spinal cord may allow the child to return to his or her baseline level of functioning and prevent further neurological deterioration.

Prophylactic antibiotic therapy 6 to 12 hours before surgery and 1 to 2 days postoperatively is effective in controlling infection for both sac repair and shunt insertion. This brief course of antibiotics has not led to resistant organisms. Prophylactic antibiotic therapy has been prescribed since the introduction of clean intermittent catheterization (CIC) to minimize treatment and prevention of urinary tract infections in children with spina bifida. Long-term use of antimicrobial prophylaxis is associated with increased bacterial resistance. Recent studies indicated that routine antibiotic prophylaxis may not be necessary and discontinuation of antibiotic prophylaxis for urinary tract infections is associated with reduced bacterial resistance to antibiotics in children with spina bifida. ^, The main cause of death in children with myelomeningocele remains increased intracranial pressure and infections of the CNS. With the use of antibiotics, shunting, and early sac closure, the survival rate has increased from 20% to 85%. ^{, ,}

Urological management

Initial newborn workup should include a urological assessment. The urology team aims to preserve renal function and promote efficient bladder management. An early start to therapy helps preserve renal function for children with spina bifida. Initially, a renal and bladder ultrasound is performed to assess those structures. Urodynamic testing can be performed to determine any blockage in the lower urinary tract. Functioning of the bladder outlet and sphincters, as well as ureteric reflux, can also be evaluated. These tests, plus clinical observations of voiding patterns, help the urologist classify the infant’s bladder function. If the bladder has neither sensory nor motor supply, a constant flow of urine is present. In this case, infection is rare because the bladder does not store urine and the sphincters are always open.

If no sensation but some involuntary muscle control of the sphincter exists, the bladder will fill, but emptying will not occur properly. Overflow or stress incontinence results in dribbling urine until the pressure is relieved. Because of constant residual urine, infection is a potential problem and kidney damage may result. When some voluntary muscle control but no sensation is present, the bladder will fill and empty automatically. The child can eventually be taught to empty the bladder at regular intervals to avoid unnecessary accidents.

Regardless of the type of bladder functioning, urodynamics should be performed on a yearly basis in order to check for infection and bladder and kidney function. This is important as urine retention in the bladder can cause urine to backflow into the kidneys, thereby damaging them. Urodynamic tests can include urine tests, blood tests, and ultrasound of the bladder and kidneys. Cystogram and cystoscopy can be applied as needed. On the basis of clinical findings and urodynamic test results, the urologist will suggest the appropriate intervention.

The goals of an effective bladder program are to reduce common problems such as hydronephrosis, overfull bladder, urinary tract infection, bladder and kidney calculi, reflux, and bladder accidents.

A bladder retraining program may include establishing a routine, diet, and healthy life style. Establishing routines involve schedules for eating, drinking, and for emptying the bladder. It is best to limit or avoid caffeine, fizzy drinks, and alcohol, as these can irritate the bladder. Manual stimulation using Crede technique (pushing on bladder with your fingertips) can help voiding.

In principle, all newborn patients are put on CIC, oxybutynin, and chemoprophylaxis immediately after closure of the back. CIC involves inserting a fine tube into the urethra to drain urine out of the bladder. This CIC program may start immediately after closure of the back. Of course, it is still a matter of discussion whether it is necessary to perform CIC from birth onward in all children. This program of CIC is typically done every 3 to 4 hours to prevent infection and maintain the urological system. Parents are taught this method and can then begin to take on this aspect of their child’s care. At the age of 4 or 5 years, children with spina bifida can be taught CIC and can become independent in bladder care at a young age. Achieving this form of independence adds to the normal psychological development of these children. Early CIC helps eliminate overflow incontinence and maintaining safe pressures in the lower urinary tract has also reduced the need for bowel augmentation of the bladder from 90% to less than 5%. Although CIC is not possible for all children with spina bifida, it remains the method of choice for bladder management.

Indwelling catheterization is a form of long-term catheterization that can be used if CIC is not successful. This involves inserting a fine tube through the urethra up into the bladder. This can be attached to either a valve or a drainage bag. The catheter will need to be replaced every few weeks. A suprapubic catheter is an alternative form of long-term catheterization and involves a small surgical procedure to place a tube directly into bladder through the abdomen. This can be attached to either a valve or a drainage bag.

Intravesical injection of botulinum toxin (Botox) into the detrusor muscle is performed as an outpatient procedure using a cystoscope under anesthesia. This injection can be repeated safely. This approach is a good temporary measure to enhance bladder capacity and decrease intravesical pressures.

Neuromodulation modifies the innervation of the bladder. Neuromodulation includes nonoperative measures such as transurethral electrical bladder stimulation by providing consistent stimulation of the efferent fibers of the sacral nerve roots or by providing rhythmic contractions of the pelvic floor; minimally invasive procedures such as implantation of a sacral neuromodulation, which is a reversible implanted (pacemaker) device; as well as operative measures that reconfigure sacral nerve root anatomy. ^, Xiao Procedure is a new procedure in which the proximal stump of the ventral root of L5 is anastomosed to the distal stump of the S3 ventral root. Early research studies about this procedure were promising, but recent studies showed that this procedure is ineffective.

The most common type of urinary diversion is the creation of a urostomy or Ileal Conduit. This involves creating a stoma using a piece of the small bowel (usually the small intestine) which will be repositioned to serve as a passage, or conduit, for urine from the ureters to a stoma. This stoma will come through the abdomen into an external pouch. A Mitrofanoff is a continent stoma created by using a small piece of the appendix or small bowel to form a conduit between the bladder and skin surface. An opening is created low on the abdomen or through the belly button, and a catheter is inserted into the opening when needed to empty the bladder. Traditional bladder reconstruction includes bladder augmentation by enlargement of the bladder with a piece of intestine to increase bladder capacity and lower intravesical pressures.

Most individuals with spina bifida will have common bowel problems including lack of control, constipation, impaction, diarrhea, and bowel accidents. Bowel management and training programs should be started early. Medications, digital stimulation, laxatives, stool softeners, suppositories, enemas and irrigation, and attention to fiber content in the diet are all of value in establishing a bowel management program. Similar to a bladder retraining program, a bowel retraining program may include establishing a routine, diet, and healthy lifestyle. Establishing routines involves maintaining schedules for eating, drinking, and for emptying the bowel. A balanced diet with plenty of fiber and enough fluid consumption helps regulate the bowel and keep stools at the right consistency to avoid constipation.

If a bowel management program is not effective, surgical treatments may be needed. The Antegrade Colonic (Continence) Enema (ACE) can be used for patients with fecal incontinence, severe constipation, or lack of anal control. This procedure is an important adjunct in the case of adults and children with problems of fecal elimination in whom standard medical therapies have failed. ^, This procedure involves creating a stoma, usually from the appendix or the small intestine. Similar to the bladder stoma, a connection is formed between the bowel and the skin. A small artificial opening is created in the umbilicus or lower abdominal wall. A catheter can be inserted into the stoma, and a washout solution is injected to carry out a controlled bowel movement. Colostomy involves diverting one end of the large bowel through an opening in the abdominal wall; a pouch is placed over the opening to collect stools. Colostomy is usually the last resort if other methods have not been successful.

Hip dislocation

Hip dislocation is commonly seen in children with spina bifida. Dislocation is probably related to paralysis, muscle imbalance, lack of sensation, and joint development, as well as contractures in muscles and soft tissues around the hip joint. ^, If not treated properly, contractures can lead to pelvic obliquity and compensatory spinal abnormality. Hip dislocation in children with spinal bifida can be paralytic or teratological. Paralytic hip dislocation is a common and complicated problem that may occur at any level of neurological deficit.

In the past, surgeries were aimed at the maintenance of hip reduction as indicated by radiographic realignment. Transfer of the iliopsoas tendon along with open reduction and capsular plication was the most common surgery in children with spina bifida in order to achieve and maintain reduction of paralytic hip dislocations.

Concerns developed regarding whether the radiological success of hip reduction led to restricted ROM and pathological fractures, thereby compromising the functional result. Subsequent studies of functional results found that the presence of a concentric reduction did not lead to improved hip ROM or the ability to ambulate. Additionally, several studies reported a high rate of complications leading to decrease in ambulatory function, limited ROM, re-dislocation, and pathological fractures in children treated surgically for the reduction of hip dislocation. Although hip reduction surgery may reduce the dislocated hip, the result must be weighed in terms of the potential for complications and functional decline.

Current treatment goals for those with hip dislocation focus on functional outcomes versus maintaining radiographical realignment. Thus current treatment focuses on maintaining level pelvis and free motion of the hips. Reports stressed that the preservation of muscle strength, specifically of the iliopsoas and quadriceps, is more relevant to determining potential for adult ambulation than the status of the hip joint.

The most important factor in determining ability to walk is the level of neural involvement and not the status of the hip. ^{, ,} A level pelvis and good hip ROM are more important than hip relocation. In general, surgical hip procedures include surgical hip reduction, soft tissue procedures, or osseous procedures. Surgical hip reduction is used to stabilize the hip and prevent further subluxations. Soft tissue procedures seek to balance muscle forces and prevent contractures. These may include transfer of iliopsoas to greater trochanter, transfer of external oblique muscle combined with adductor tenotomy or transfer of adductors to the ischium, or tenotomy of iliopsoas and adductor muscles to relieve the muscle balance of the hip. Osseous procedures are aiming to correct deficiency of the acetabulum as well as to correctly center the femoral head in the acetabulum. These procedures may include Shelf procedure, Pemberton osteotomy, or Chiari osteotomy. Femoral osteotomy may be performed to correct rotational and angular deformity.

In those with a thoracic lesion with both hips unstable or who are unable to walk, surgeries to reduce hips are not indicated. Treatment should be directed at preventing or releasing the contractures. Similarly, in those with lumbar lesions and asymmetry caused by contracture, treatment will be directed at releasing the contracture and no attempts will be made to reduce the hip. This can be accomplished by exercises, positioning, or anterior hip release for hip flexion contractures. Muscle transfers alone usually are not effective in producing stability of the hip in these children. Hip dislocations in those with lower lumbar (L4 or below) or sacral level lesions should be considered as lever-arm dysfunction, and surgical hip relocation is indicated. ^, Reduction of the hip in these children is aimed at the prevention of progressive subluxation, which will ultimately interfere with walking. Osteotomy can be indicated to avoid future leg length discrepancy or pelvic obliquity. Immobilization after hip dislocation may lead to a frozen, immobile joint from an open reduction procedure, re-dislocation from a lack of significant dynamic forces available for joint stability around the hip joint, and an increased fracture risk. Recently, a questionnaire called the Spina Bifida Hips Questionnaire (SBHQ), which was developed to evaluate the ADLs important to children with spina bifida and dislocated hips along with their families, has demonstrated construct validity as well as reliability.

Knee valgus stress

Many children with spina bifida who walk have excessive trunk and pelvic movement, knee flexion contractures, and rotational malalignment that may lead to excessive knee valgus stress. Valgus knee deformity is frequently seen in low-lumbar and sacral-level patients leading to instability, pain, and arthritis in adulthood. The most common deformities leading to this problem are rotational malalignment of the femur and femoral anteversion in association with excessive anterior tibial torsion. The knee valgus deformity is influenced by increased lateral truck sway, weak hip abductor muscles, and internal hip rotation in combination with increased knee flexion and valgus foot deformity.

These deformities should be addressed via surgical correction, as excessive knee valgus stress can lead to knee pain and arthritis in adulthood. ^{, , ,} Surgical correction of excessive rotational deformities has been shown to lead to a significant improvement in knee stress and pain and may prevent the onset of late degenerative changes. If knee valgus is associated with knee flexion contracture or hindfoot valgus, the surgical correction of these deformities is required at the same setting. In addition to physical therapy and exercises, the use of assistive aids, bracing, or a combination of both should be encouraged to increase stance-phase stability, decrease stress in the knee joint, and maintain long-term joint viability. ^,

Rotational deformities

Rotational deformities of the lower extremities are frequently seen in both ambulatory and nonambulatory patients with spina bifida. Femoral torsion may be present at birth in newborns and does not seem to decrease with growth due to abnormal gait and activity level; it may be secondary to foot deformities. Tibial torsion may be congenital secondary to clubfoot or other foot deformities; it may also be secondary to muscle imbalance or associated foot deformity.

For the nonambulatory children, torsional problems are largely cosmetic. For the ambulatory child, torsional deformities in the lower extremity can be addressed using Torsional Splints attached to an AFO, often referred to as a twister cable. In the long term, significant rotational deformities may be addressed surgically with de-rotational osteotomy.

Scoliosis

The prevalence of scoliosis in spina bifida is estimated to be as high as 50%. Increasing scoliosis can lead to the loss of trunk stability when curves are greater than 40 degrees and when associated pelvic obliquity becomes 25 degrees or more. Scoliosis can progress to affect sitting and standing balance. It may affect the ability to sit, stand, and walk and interferes with positioning in the wheelchair. Surgical intervention, often recommended to prevent further progression, may improve or further impair sitting balance, ambulation, and performance of ADLs. Various authors have reported that although surgery can improve curves by up to 50%, surgical morbidity must be considered, with complications possibly being as high as 40% to 50%. Functional benefits are largely unsubstantiated owing to poorly constructed studies. Wai ^, suggests that spinal deformity may not affect overall physical function or self-perception. After surgical correction, it may take up to 18 months to appreciate functional improvement, and walking may be difficult for those who were just exercise ambulators before correction. Although surgical repair of scoliosis does improve quality of life in patients with cerebral palsy and muscular dystrophy, this has not been demonstrated in those with spina bifida. Interventions such as chair modifications to shift the trunk to improve balance in the coronal plane and reduce pelvic obliquity and truncal asymmetry should be considered as a first option, before surgical correction. ^,

Back pain

Back pain needs to be efficaciously evaluated in those with spina bifida who report experiencing it. Knowing when the patient experiences pain, what increases pain, what positions exacerbate pain, and what region of the body is affected can help lead to appropriate referral, testing, and management. Knowing if your patient has a shunt, spinal rods, and/or a Chiari malformation will also be important to your assessment and management. Pain in the neck, shoulders, and upper back with associated weakness and/or abnormal sensory findings should be evaluated by the treating neurosurgeon to rule out shunt malfunction. Spinal rods that have broken or that are breaking through the skin may also be a source of pain in this area. Pain not caused by rods, a shunt, Chiari issues, or a syrinx may have a mechanical cause and could be a result of poor posture, tension, or weight gain. A patient who reports low back pain may have a symptomatic tethered cord if the patient is also reporting changes in gait, increased tripping or falling, bladder changes, and/or pain shooting down the legs. Manual muscle testing (MMT) and urodynamic testing are appropriate at this point and should be compared with baseline testing findings. Mechanical low back pain may be a result of abnormal gait mechanics, asymmetrical strength, and use of older orthotics that no longer fit. Assessment of seating and support systems, including cushions, and gait mechanics with the use of orthotics and ambulatory aids are mandatory to increase stability and redistribute balance over stressed joints, maximizing reduction of the patient’s pain and discomfort. Strengthening, particularly of the gluteal muscles, for those who are ambulatory may also be indicated. In addition, programs aimed at weight reduction may be necessary to alleviate stress and pain to preserve long-term viability of tissues. In addition, for women, the chest may cause tension on the upper back, and breast reduction has been advocated for some to relieve this tension.

Foot deformity

Almost all children with spina bifida will experience problems with foot deformity. Foot deformities are caused when muscle weakness leads to abnormal positioning in utero or may occur from ongoing muscle imbalance, postural effects of gravity, and growth. Foot deformities include calcaneus, equinus, varus, valgus, clubfoot, vertical talus, or a combination of deformities. A plantigrade foot in neutral position is essential for optimal walking, and a well-positioned foot may protect against skin breakdown. Foot deformity can cause difficulty with shoe wear and bracing.

The goal of treatment of the foot in spina bifida should be a flexible and supple foot. An insensate flail foot often becomes rigid over time, and foot management can become complicated by pressure sores. Up to 95% of patients will use an orthosis, and a supple flail foot will be easier to manage over time. Surgeries that are extraarticular with avoidance of arthrodesis, as well as simple tenotomies versus tendon releases and lengthenings, may best manage outcomes for bracing and ambulation. Clubfoot or equinovarus deformities may be managed with early and intensive taping in the newborn period, known as the French method, ^, as well as by stretching and casting and surgical intervention. The Ponseti method, advocated by some, has also been reported to have positive outcomes; however, the significant investment in time and commitment by the family for frequent cast changes may affect the ability to carry out other ADLs without disruption. Recurrent clubfeet are difficult to treat, but a talectomy with calcaneo-cuboid fusion may be used for recurrent clubfeet. In those with lipomas, foot deformity that may be acquired over time is best managed in a similar manner as in equinovarus deformities. Maintaining a supple and plantigrade foot with adequate muscle balance and using soft tissue correction through tendon lengthening, tendon transfer, and plantar fascial release are recommended until 8 years of age. After that time, deformities may become more rigid and may necessitate more bony procedures.

Valgus deformity can also occur at the ankle joint and can be easily treated with guided growth principles in a growing child, which allows for gradual correction of the deformity by tethering the medial side of the growth plate. ^, Severe hindfoot valgus can be treated by medial displacement osteotomy of the calcaneus in children with spina bifida. This allows preservation of motion with osteotomies opposed to arthrodesis of joints.

Calcaneus deformity is not very common but may occur in patients with unopposed anterior tibialis activity, leading to excessive pressure on the heel area with subsequent risk of skin breakdown. Tendon transfer or release do not seem to be successful. Long standing calcaneal deformity may be addressed with triple arthrodesis (fusing the three joints about the hindfoot).

Osteoporosis, osteopenia, and fracture

Osteoporosis (thinning of the bone) and osteopenia (low bone mineral density [BMD]) in the legs and spine have been described in children and teens with spina bifida. These conditions increase the risk of fracture, increase the time for healing after fracture, and may lead to back pain. A study by Valtonen and colleagues in 2006 documented the occurrence of osteoporosis in adults with spina bifida. This condition is often not recognized. Medical factors may contribute to increase the risk of osteoporosis, osteopenia, and fracture, such as physical inactivity, lack of physical loading and weight bearing due to lack of ambulation or inability to ambulate, decreased vitamin D, diminished exposure to sunlight, urinary diversion, renal insufficiency, hypercalciuria, medication for epilepsy, and oral cortisone treatment for more than 3 months. ^{, ,} It can be assumed that patients with meningomyelocele are at potential risk for development of osteoporosis at a younger age because of flaccidity, impaired walking ability, and subsequent low physical loading of the lower limbs. Older age and higher levels have been associated with increased numbers of fractures in spina bifida. The optimal strategies for prevention and treatment of osteoporosis in this population have not been established. Further research is required to see if the methods used to prevent and treat osteoporosis in individuals without spina bifida also work for teens and adults who have spina bifida. Considering the effects of prolonged immobilization on independence in daily activities and quality of life, there should be no disagreement that all efforts are necessary to prevent these fractures. Furthermore, osteoporotic fracture may lead to a vicious cycle of immobilization, decreased bone density, and repeated fractures. Annual incidence of fracture is 0.029% in adolescents and 0.018% in adults.

Management of bone fragility in children with disabilities has been limited to conservative measures such as standing program, loading and weight-bearing activities, and calcium and vitamin D intake. Those measures may not be enough to treat osteoporosis. The effects of standing programs on bone density are unclear, ^, although standing with the use of a standing frame or vibration therapy appear to increase BMD in other children with disabilities. ^, Studies have shown promising results of regular functional electric stimulation–assisted training, but this is often nearly impossible to carry out in daily life. Additionally, the period of immobilization after a surgical intervention should be reduced, if possible, and weight bearing should be allowed as soon as possible. Management should include attention to nutritional factors, in particular, adequate intake of calcium and vitamin D. However, constipation secondary to neuropathic bowel is a frequent problem in patients with spina bifida, and supplementation with calcium may exacerbate it. Antiresorptive drugs may be used for adults with low BMD. Parathyroid hormone therapy would be an alternative if the patient fails to gain adequate BMD. This therapy is not used in children and adolescents due to the risk of osteosarcoma. Bisphosphonates may be used to increase bone strength in children with osteoporosis, but its use should be weighted along with the serious side effects.

The prevention of fractures should be among the major goals in the rehabilitation of people with meningomyelocele. The assessment of BMD is worthwhile in nonambulatory children and patients with risk factors for osteoporosis, because low BMD is a known risk factor for fractures.

Postoperative management

Care should be taken to avoid postoperative complications such as skin breakdown and postimmobilization fractures in the postoperative period. To decrease the risk of nonunion and allow for early mobilization and weight bearing, one should consider rigid internal fixation versus Kirschner wire fixation. After surgery, immobilization in a custom-molded body splint rather than a hip spica cast is preferred. Postoperative physical therapy should begin as soon as wounds are stable and healing is occurring. Therapy should focus on ROM (active and passive) and early weight bearing. Crawling should be strictly forbidden for a minimum of 3 to 4 weeks postimmobilization to reduce the risk of fracture.

Assessing muscle strength

Loss of muscle strength is one of the main impairments in children with spina bifida. Therefore assessment of muscle strength and timely detection of muscle weakness is critical and should be assessed regularly in the growing child to monitor any changes in strength. Accurate and reliable strength measures are essential in early and ongoing management of a child with spina bifida.

Assessing the muscle strength of children, in general, and young children with spina bifida, in particular, can be a challenge. Several alternatives to MMT have been advocated to evaluate motor function in children. MMT is used worldwide with children with spina bifida. Alternate methods to MMT for strength assessment of children with spina bifida include hand-held dynamometry (HHD), isokinetic strength testing, somatosensory evoked potentials, and electromyography. Muscle contour and symmetry can be used as a subjective method to assess muscle strength in some children. Observation of significant muscle atrophy and limb contour can be indicative of significant muscle strength.

In the newborn, infant, very young child, or a child who is not able to understand or follow directions, the traditional form of MMT is not appropriate or possible. Therefore alternate methods to assess muscle strength in this population are necessary. Observation of infant spontaneous movements, such as leg kicking and responses to stimuli, can be used to assess strength in the newborn or infant. Observation of the infant or young child performing typical movement activities or functional tasks can be used to assess strength. This may include observing the child moving their hand to reach for a toy, kicking their leg against gravity, or using the hip flexors during creeping.

In the newborn, testing may be done in the first 24 to 48 hours before the back is surgically closed. In this case, care must be taken not to injure the exposed neural tissue during testing. Prone and side lying to either side are the most convenient and safe positions for evaluation during this time. Subsequent testing is done soon after the back has been closed and as indicated throughout childhood.

In evaluating the newborn, the importance of alertness is essential. A sleeping or drowsy infant will not respond appropriately during the evaluation. The infant must be in the alert or crying state to elicit the appropriate movement responses. Testing hungry or crying infants provides an advantage because they are likely to demonstrate more spontaneous movements in these behavioral states. The cumulative effect of a variety of sensory stimuli may be more effective in bringing the infant to alertness than using one stimulus in isolation. For example, the infant may be picked up and rocked vertically to allow maximum stimulation to the vestibular system and to help bring the child to an alert state. In addition, the therapist may talk to the child to help him or her fixate visually on the therapist’s face. Tactile stimuli above the level of the lesion further add to the child’s level of arousal, thus contributing to more conclusive test results. In this way, the CNS receives an accumulation of information from a variety of sensory systems rather than relying on transmission from one system that may be weak or inefficient.

As the child is aroused, spontaneous movements can be observed and muscle groups palpated. Additional methods to stimulate movement may be necessary. For example, tickling the infant generally produces a variety of spontaneous movements in the upper and lower extremities. Passive positioning of children in adverse positions may stimulate them to move. For example, if the legs are held in marked hip and knee flexion, the infant may attempt to use extensor musculature to move out of that position. If the legs are held in adduction, the child may abduct to get free. Holding a limb in an antigravity position may elicit an automatic “holding” response from a muscle group when spontaneous movements cannot be obtained in any other way.

In grading muscle strength, differentiation between spontaneous, voluntary movement, and reflexive movement is important. After the severing of a spinal cord, distal segments of the cord may respond to stimuli in a reflexive manner. This results from the preservation of the spinal reflex arc and is known as distal sparing. If distal sparing of the spinal cord is present, the muscles may respond to stimulation or muscular stretch with reflexive, stereotypical movement patterns. The quality of this reflexive movement will be different from that of spontaneous movement and must be distinguished when testing for the level of voluntary muscle functioning.

Muscle strength is generally graded for groups of muscles and can be graded by using either a numerical scale (1 to 5), an alphabetical designation ( Fig. 13.15 ), or simply by noting presence or absence of muscular contraction by a plus or a minus on the muscle test form. The last method may be sufficient initially, but as the child matures, a more definitive muscle grade should be determined.

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

Contemporary issues and theories of motor control, motor learning, and neuroplasticity Medical and developmental challenges of infants in neonatal intensive care: Management and follow-up considerations Neuromuscular diseases Brain tumors Aging, dementia, and disorders of cognition Electrophysiological testing and electrical stimulation in neurological rehabilitation

Stay updated, free articles. Join our Telegram channel

Join