In this text, the term paraplegia denotes partial or complete weakness of both legs, and the term quadriplegia denotes partial or complete weakness of all limbs, thereby obviating need for the terms paraparesis and quadriparesis. Many conditions described fully in this chapter are abnormalities of the spinal cord. The same spinal abnormality can cause paraplegia or quadriplegia, depending on the location of the injury. Therefore, the discussion of both is together in this chapter.
Approach to Paraplegia
Weakness of both legs, without any involvement of the arms, suggests an abnormality of either the spinal cord or the peripheral nerves. Ordinarily, a pattern of distal weakness and sensory loss, muscle atrophy, and absent tendon reflexes provides recognition of peripheral neuropathies (see Chapter 7 , Chapter 9 ). In contrast, spinal paraplegia causes spasticity, exaggerated tendon reflexes, and a dermatomal level of sensory loss. Disturbances in the conus medullaris and cauda equina, especially congenital malformation, may produce a complex of signs in which spinal cord or peripheral nerve localization is difficult. Indeed, both may be involved. Spinal paraplegia may be asymmetric at first, and then the initial feature is monoplegia (see Chapter 13 ). When anatomical localization between the spinal cord and peripheral nerves is difficult, electromyography (EMG) and nerve conduction studies are useful in making the distinction.
Cerebral abnormalities sometimes cause paraplegia. In such a case, the child’s arms as well as the legs are usually weak. However, leg weakness is so much greater than arm weakness that paraplegia is the chief complaint. It is important to remember that both the brain and the spinal cord may be abnormal and that the abnormalities can be in continuity (syringomyelia) or separated (Chiari malformation and myelomeningocele).
Spinal Paraplegia and Quadriplegia
Box 12.1 lists conditions that cause acute, chronic, or progressive spinal paraplegia. In the absence of trauma, spinal cord compression and myelitis are the main causes of an acute onset or rapidly progressive paraplegia. Spinal cord compression from any cause is a medical emergency requiring rapid diagnosis and therapy to avoid permanent paraplegia. Corticosteroids have the same anti-inflammatory effect on the spinal cord as on the brain and provide transitory decompression before surgery.
C ongenital M alformations
Arachnoid cyst
Arteriovenous malformations
Atlantoaxial dislocation
Caudal regression syndrome
Dysraphic states
Chiari malformation
Myelomeningocele
Tethered spinal cord
Syringomyelia (see Chapter 9 )
F amilial S pastic P araplegia
Autosomal dominant
Autosomal recessive
X-linked recessive
I nfections
Asthmatic amyotrophy (see Chapter 13 )
Diskitis
Epidural abscess
Herpes zoster myelitis
Polyradiculoneuropathy (see Chapter 7 )
Tuberculous osteomyelitis
L upus M yelopathy
M etabolic D isorders
Adrenomyeloneuropathy (adrenoleukodystrophy)
Argininemia
Krabbe disease
N eonatal C ord I nfarction
T ransverse M yelitis
Devic disease
Encephalomyelitis
Idiopathic
Trauma
C oncussion
Epidural hematoma
Fracture dislocation
N eonatal C ord T rauma ( see C hapter 6 )
T umors
Astrocytoma
Ependymoma
Ewing’s sarcoma
Neuroblastoma
Several techniques are available to visualize the spinal cord. Each has its place, and sometimes the use of more than one technique achieves a comprehensive picture of the disease process. However, magnetic resonance imaging (MRI) is clearly the procedure of choice to visualize the spine, and should be used first. Computed tomography (CT) and radioisotope bone scanning are useful for visualizing the vertebral column, especially when osteomyelitis is a consideration. Isotope bone scans localize the process but rarely provide an etiology.
Symptoms and Signs
Clumsiness of gait, refusal to stand or walk, and loss of bladder or bowel control are the common complaints of spinal paraplegia. Clumsiness of gait is the usual feature of slowly progressive disorders. When functional decline is sufficiently insidious, the disturbance may go on for years without raising concern. Refusal to stand or walk is a symptom of an acute process. When a young child refuses to support weight, the underlying cause may be weakness, pain, or both.
Scoliosis is a feature of many spinal cord disorders. It occurs with neural tube defects, spinal cord tumors, and several degenerative disorders. It also occurs when the paraspinal muscles are weaker on one side of the spine than on the other side. The presence of scoliosis, in females before puberty and in males of all ages, should strongly suggest either a spinal cord disorder or a neuromuscular disease (see Chapter 6 , Chapter 7 ).
Abnormalities in the skin overlying the spine, such as an abnormal tuft of hair, pigmentation, a sinus opening, or a mass, may indicate an underlying dysraphic state. Spina bifida is usually an associated feature.
Foot deformities and especially stunted growth of a limb are malevolent signs of lower spinal cord dysfunction. The usual deformity is foreshortening of the foot (pes cavus). In such cases, disturbances of bladder control are often an associated feature.
Brief, irregular contractions of small groups of muscles that persist during sleep characterize spinal myoclonus . The myoclonic contractions are often mistaken for seizure activity or fasciculations. The cause of myoclonus is irritation of pools of motor neurons and interneurons, usually by an intramedullary tumor or syrinx. The dermatomal distribution of the myoclonus localizes the site of irritation within the spinal cord. Alternatively, spinal myoclonus can present as sequelae from severe traumatic or hypoxic brain injury, due to disinhibition of anterior horn cells or multifocal cortical hyperexcitability ( ).
Congenital Malformations
Some congenital malformations, such as caudal regression syndrome and myelomeningocele, are obvious at birth. Many others do not cause symptoms until adolescence or later. Congenital malformations are always a consideration when progressive paraplegia appears in childhood.
Arachnoid Cysts
Arachnoid cysts of the spinal cord, like those of the brain (see Chapter 4 ), are usually asymptomatic and discovered incidentally on imaging studies. Familial cases should suggest neurofibromatosis type 2 (see Chapter 5 ).
Clinical Features
Arachnoid cysts may be single or multiple and are usually thoracic. Symptomatic arachnoid cysts are unusual in childhood and encountered more often in adolescents and young adults. The features are back or radicular pain and paraplegia. Standing intensifies symptoms, and changes in position may relieve or exacerbate symptoms. The pain tends to increase in severity with time.
Diagnosis
MRI is the diagnostic modality of choice. The cyst has the same MRI characteristics as cerebrospinal fluid.
Management
Shunting of a symptomatic cyst is curative. However, it is common to blame a subarachnoid cyst for symptoms that have another cause.
Arteriovenous Malformations
Arteriovenous malformations of the spinal cord are uncommon in childhood and even rarer in infancy, although case reports do exist ( ).
Clinical Features
The progression of symptoms is usually insidious, and the time from onset to diagnosis may be several years. Subacute or chronic pain is the initial feature in one-third of patients and subarachnoid hemorrhage in one-quarter. Paraplegia is an early feature in only one-third, but monoplegia or paraplegia is present in almost all children at the time of diagnosis. Most children have a slowly progressive spastic paraplegia and loss of bladder control.
When subarachnoid hemorrhage is the initial feature, the malformation is more likely to be in the cervical portion of the spinal cord. Blunt trauma to the spine may be a precipitating factor. The onset of paraplegia or quadriplegia is then acute and associated with back pain. Back pain and episodic weakness that improve completely or in part may be initial features in some children, but impairment is progressive. This type of presentation is misleading, and the diagnosis often delayed.
Diagnosis
MRI is the first step in diagnosis. It distinguishes intramedullary from dural and extramedullary locations of the malformation and even allows recognition of thrombus formation. Arteriography is still necessary to demonstrate the intramedullary extent of the malformation and all of the feeding vessels.
Management
The potential approaches to therapy for intraspinal and intracranial malformations are similar (see Chapter 4 ).
Atlantoaxial Dislocation
The odontoid process is the major factor preventing dislocation of C1 onto C2. True aplasia of the odontoid process is rare and leads to severe instability. Hypoplasia of the odontoid process can occur alone or as part of Morquio syndrome, other mucopolysaccharidoses, Klippel-Feil syndrome (see Chapter 18 ), several types of genetic chondrodysplasia, and some chromosomal abnormalities ( ). Asymptomatic atlantoaxial subluxation may occur in 20 % of children with Down syndrome secondary to congenital hypoplasia of the articulation of C1 and C2; symptomatic dislocation is much less common.
Clinical Features
Congenital atlantoaxial dislocation produces an acute or slowly progressive quadriplegia that may begin any time from the neonatal period to adult life. When the onset is in a newborn, the clinical features resemble an acute infantile spinal muscular atrophy (see Chapter 6 ). The infant has generalized hypotonia with preservation of facial expression and extraocular movement. The tendon reflexes are absent at first but then become hyperactive.
Dislocations during childhood frequently follow a fall or head injury. In such cases, symptoms may begin suddenly and include not only those of myelopathy but also those related to vertebral artery occlusion.
Morquio syndrome is primarily a disease of the skeleton, with only secondary abnormalities of the spinal cord. Beginning in the second year or thereafter, the following features develop in affected children: prominent ribs and sternum, knock-knees, progressive shortening of the neck, and dwarfism. The odontoid process is hypoplastic or absent. Acute, subacute, or chronic cervical myelopathy develops, sometimes precipitated by a fall. Loss of endurance, fainting attacks, and a “pins and needles” sensation in the arms characterize an insidious onset of symptoms.
The essential feature of the Klippel-Feil syndrome is a reduced number and abnormal fusion of cervical vertebrae. As in Morquio syndrome, the head appears to rest directly on the shoulders, the posterior hairline is low, and head movement in all directions is limited. Elevation of the scapulae and deformity of the ribs ( Sprengel deformity ) are often present. Weakness and atrophy of the arm muscles and mirror movements of the hands are features of evolving paraplegia. Associated abnormalities may be present in the genitourinary, cardiac, and musculoskeletal systems.
Symptomatic atlantoaxial dislocation in children with Down syndrome may occur anytime from infancy to the twenties. Females are more often affected than are males. Symptoms include neck pain, torticollis, and an abnormal gait. Spinal cord compression is progressive and leads to quadriplegia and urinary incontinence.
Diagnosis
C1 usually moves anteriorly to C2. Flexion radiographs assess the separation between the dens and the anterior arch of C1. MRI is best to view the relationship between the cord and the subluxing bones. Flexion-extension plain films of the cervical spine are often used to make the diagnosis, but CT or MRI may be more useful to assess for associated abnormalities. The neck of children with trisomy 21 should not be flexed for lumbar puncture as this may dislocate the atlantoaxial join and cause acute spinal cord compression.
Management
Surgical stabilization of the atlantoaxial junction is a consideration in any child with evidence of spinal cord compression. The choice of surgical procedure depends on the mechanism of compression.
Caudal Regression Syndrome
The term caudal regression syndrome covers several malformations of the caudal spine that range from sacral agenesis to sirenomelia, in which the legs are fused together (also known as Mermaid syndrome). The mechanism of caudal regression is incompletely understood, but some cases are clearly genetic in origin, while approximately 20 % of mothers of children with caudal dysgenesis have insulin-dependent diabetes mellitus ( ). Although the name implies regression of a normally formed cord, defects in neural tube closure and prosencephalization are often associated features. The clinical spectrum varies from absence of the lumbosacral spinal cord, resulting in small, paralyzed legs, to a single malformed leg associated with malformations of the rectum and genitourinary tract.
Chiari Malformation
The type I Chiari malformation is extension of the cerebellar tonsils through the foramen magnum, sometimes with associated hydrosyringomyelia. The type II malformation combines the cerebellar herniation with distortion and dysplasia of the medulla and occurs in more than 50 % of children with lumbar myelomeningocele. The herniated portion may become ischemic and necrotic and can cause compression of the brainstem and upper cervical spinal cord.
Ectopic expression of a segmentation gene in the rhombomeres may explain the Chiari malformation and also the brainstem anomalies, myelodysplasia, and the defective bone formation that results in a small posterior fossa ( ).
Clinical Features
Most Chiari I malformations are discovered as an incidental finding on an MRI ordered because of headache. The malformation is rarely the cause of the headache. The initial features of a symptomatic Chiari malformation are usually insidious. Oropharyngeal dysfunction is a presenting feature in 35 % of children less than 6 years of age, followed by scoliosis (23 %) and head and neck pain (23 %) ( ). Among older children, headache and neck pain are the first features in 38 % and weakness in 56 %. Eighty percent show motor deficits on examination, usually atrophy and hyporeflexia in the arms and spasticity and hyperreflexia in the legs. Sensory loss and scoliosis are each present in half of cases.
Type II malformation should be suspected in every child with myelomeningocele. The child may have hydrocephalus secondary to aqueductal stenosis or by an obstruction of the outflow of cerebrospinal fluid from the fourth ventricle due to herniation. Respiratory distress is the most important feature of the Chiari II malformation. Rapid respirations, episodes of apnea, and Cheyne-Stokes respirations may occur. Other evidence of brainstem compression includes poor feeding, vomiting, dysphagia, and paralysis of the tongue. Sudden cardiorespiratory failure is the usual cause of death.
Diagnosis
MRI is the best method to visualize the posterior fossa and cervical cord. CT is useful to further delineate bony abnormalities.
Management
Posterior fossa decompression is the usual technique to manage newborns with myelomeningocele and respiratory distress caused by the Chiari malformation. Unfortunately, the results are not encouraging. Posterior fossa decompression is usually successful in relieving symptoms of cord compression in older children without myelomeningocele. Ventriculoperitoneal shunt may be required as well.
Myelomeningocele
Dysraphia comprises all defects in the closure of the neural tube and its coverings. Closure occurs during the third and fourth weeks of gestation. The mesoderm surrounding the neural tube gives rise to the dura, skull, and vertebrae but not to the skin. Therefore, defects in the final closure of the neural tube and its mesodermal case do not preclude the presence of a dermal covering.
Despite extensive epidemiological studies, the causes of myelomeningocele remain unknown. Causes are likely to be multifactorial, including both genetic and environmental factors. Because women who have previously had a child with dysraphia have an approximate 2 % risk of recurrence, prenatal diagnosis is available to prevent repetition.
α-Fetoprotein, the principal plasma protein of the fetus, is present in amniotic fluid. The concentration of α-fetoprotein in the amniotic fluid increases when plasma proteins exude through a skin defect. Prenatal diagnosis is possible by the combination of measuring the maternal serum concentration of α-fetoprotein and ultrasound examination of the fetus.
The incidence of dysraphic defects has been declining in the United States and the United Kingdom. Antenatal screening alone does not explain the decline; changes in critical environmental factors may be important. Because the ingestion of folic acid supplements during early pregnancy reduces the incidence of neural tube defects, the consumption of 0.4 mg of folic acid daily is advisable for all women of childbearing age. Women with a prior history of delivering a child with a neural tube defect should take 4 mg/day of folic acid from at least 4 weeks before conception through the first 3 months of pregnancy.
Clinical Features
Spina bifida cystica, the protrusion of a cystic mass through the defect, is an obvious deformity of the newborn’s spine. More than 90 % are thoracolumbar. Among newborns with spina bifida cystica, the protruding sac is a meningocele without neural elements in 10–20 % and is a myelomeningocele in the rest. Meningoceles tend to have a partial dermal covering and are often pedunculated, with a narrow base connecting the sac to the underlying spinal cord. Myelomeningoceles usually have a broad base, lack epithelial covering, and ooze a combination of cerebrospinal fluid and serum. Portions of the dome contain exposed remnants of the spinal cord.
In newborns with spina bifida cystica, it is important to determine the extent of neurological dysfunction caused by the myelopathy, the potential for the development of hydrocephalus, and the presence of other malformations in the nervous system and in other organs. When myelomeningocele is the only deformity, the newborn is alert and responsive and has no difficulty in feeding. Diminished consciousness or responsiveness and difficulty in feeding should suggest perinatal asphyxia or cerebral malformations such as hydrocephalus. Cyanosis, pallor, or dyspnea suggests associated malformations in the cardiovascular system. Multiple major defects are present in approximately 30 % of cases.
The spinal segments involved can be determined by locating the myelomeningocele with reference to the ribs and iliac crest. Several patterns of motor dysfunction are observable depending on the cyst’s location. Motor dysfunction results from interruption of the corticospinal tracts and from dysgenesis of the segmental innervation. At birth, the legs are flaccid, the hips are dislocated, and arthrogryposis of the lower extremities is present. Spastic paraplegia, a spastic bladder, and a level of sensory loss develop in infants with a thoracic lesion. Segmental withdrawal reflexes below the level of the lesion, which indicate the presence of an intact but isolated spinal cord segment below the cyst, are present in half of patients. Infants with deformities of the conus medullaris maintain a flaccid paraplegia, have lumbosacral sensory loss, lack a withdrawal response in the legs, and have a distended bladder with overflow incontinence.
Only 15 % of newborns with myelomeningocele have clinical evidence of hydrocephalus at birth, but ultrasound detects hydrocephalus in 60 % of affected newborns. Hydrocephalus eventually develops in 80 %. The first clinical features of hydrocephalus often follow the repair of the myelomeningocele, but the two are not related. Aqueductal stenosis and the Chiari malformation are the cause of hydrocephalus in the majority of infants with myelomeningocele.
Diagnosis
Examination alone establishes the diagnosis of spina bifida cystica. EMG may be useful to clarify the distribution of segmental dysfunction. Cranial ultrasound to look for hydrocephalus is required for every newborn. MRI is useful to define malformations of the brain, especially the Chiari malformation (see Figure 10-6 ). Therapeutic decisions may require such information. Even in the absence of hydrocephalus at birth, repeat ultrasound examinations in 2 to 4 weeks are required to evaluate ventricular size.
Management
The chance of surviving the first year is poor without back closure shortly postpartum. However, closure is not a surgical emergency and delays of a week or longer do not influence the survival rate. Other factors associated with increased mortality are a high spinal location of the defect and clinical hydrocephalus at birth. The long-term outcome depends on the degree of neurological deficit from the spinal defect and any associated brain abnormalities.
Tethered Spinal Cord
A thickened filum terminale, a lipoma, a dermal sinus, or diastematomyelia may anchor the conus medullaris to the base of the vertebrae. Spina bifida occulta is usually an associated feature. As the child grows, the tether causes the spinal cord to stretch and the lumbosacral segments to become ischemic. The mitochondrial oxidative metabolism of neurons is impaired, and neurological dysfunction follows.
Dermal sinus is a midline opening of the skin usually marked by a tuft of hair or port-wine stain. An abnormal invagination of ectoderm into the posterior closure site of the neural tube causes the problem. Most sinuses terminate subcutaneously as a blind pouch or dermoid cyst. Others extend through a spina bifida to the developing neuraxis, at which point they attach to the dura or the spinal cord as a fibrous band or dermoid cyst. Such sinuses tether the spinal cord and serve as a route for bacteria from the skin to reach the subarachnoid space and cause meningitis.
Diastematomyelia consists of a bifid spinal cord (also called diplomyelia) that is normal in the cervical and upper thoracic regions and then divides into lateral halves ( Figure 12-1 ). Two types of diastematomyelia occur with equal frequency. In one type, a dural sheath surrounds each half of the cord and a fibrous or bony septum separates the two halves. Once the cord separates, it never rejoins. In the other type, a single dural sheath surrounds both halves and a septum is not present. The two halves rejoin after one or two segments. Therefore, the cause of spinal cord splitting is not the presence of a septum, but rather a primary disturbance in the formation of luminal borders caused by faulty closure of the neural tube. It is usually associated with other dysraphic disturbances such as spina bifida occulta or cystica.
Clinical Features
The initial features of a tethered spinal cord occur at any age from infancy to young adulthood. The clinical features vary with age. External signs of spinal dysraphism (tuft of hair, subcutaneous lipoma, and dermal sinus) are present in more than half of patients, and spina bifida occulta or sacral deformity is present in almost 90 %.
Infants and young children are most likely to show clumsiness of gait, stunted growth, or deformity of one foot or leg, and disturbances in bladder or bowel function. These may occur alone or in combination. Consequently, the first specialist consulted may be an orthopedic surgeon, urologist, neurologist, or neurosurgeon. The progression of symptoms and signs is insidious, and a static problem is the first diagnosis in most children. Children with only a clumsy gait or disturbances in urinary control tend to have normal or exaggerated tendon reflexes and an extensor plantar response. In some children, diminished or absent ankle tendon reflexes are noted on one or both sides. Children with foot deformity usually have pes cavus and stunted growth of the entire leg. The other leg may appear normal or have a milder deformity without a growth disturbance. Diminished tendon reflexes in the deformed foot are more likely than increased reflexes.
The initial feature of tethered spinal cord in older children and adolescents is either clumsiness of gait or scoliosis. Bilateral, but mild, foot deformities are sometimes present and urinary incontinence and constipation reported. Exaggerated knee and ankle tendon reflexes are usual, and the plantar response is usually extensor.
Diagnosis
EMG is not a useful screening procedure, as the results are usually abnormal. Radiographs of the spine may show a spina bifida, but MRI is the appropriate diagnostic test and is particularly useful in the detection of lumbosacral lipoma. The essential feature of a tethered spinal cord is a low-lying conus medullaris. At 28 weeks’ gestation, the tip of the conus is at the L3 vertebral level. It generally raises one level by 40 weeks’ gestation. A conus that extends below the L2 to L3 interspace in children 5 years and older is always abnormal.
Management
Surgical relief of the tethering prevents further deterioration of neurological function and improves preexisting deficits in up to 50 % of children ( ).
Hereditary Spastic Paraplegia
Hereditary spastic paraplegia (HSP) is a heterogeneous group of genetic disorders in which the prominent clinical feature is progressive spastic paraplegia. Some families have pure or uncomplicated HSP, in which neurological impairment is limited to progressive spastic paraplegia, a hypertonic urinary bladder disturbance, and mild diminution of vibration and position sense. Others have complicated or complex HSP in which the spastic paraplegia is associated with other neurological findings such as seizures, dementia, amyotrophy, extrapyramidal disturbance, or peripheral neuropathy ( ). Genetic transmission of HSP is by autosomal dominant inheritance in 70 % of cases and by autosomal recessive inheritance in 25 %. Genetic heterogeneity exists even within the dominant and recessive forms. The X-linked form is uncommon, usually congenital, and almost always complicated .
Autosomal Dominant Inheritance
Children with autosomal dominant spastic paraplegia may have pure or complicated spastic paraplegia.
Clinical Features
The age at onset ranges from infancy to late adulthood, with the mean at 29 years. Early and late onset cases may occur among members of the same family. Motor milestones are normal in affected infants except for toe walking. Frequently, the diagnosis in such children is cerebral palsy, especially if the affected parent is asymptomatic or has only a mildly stiff gait. Increased tone is more prominent than weakness. Tone increases slowly for several years and then stabilizes. At this point, the child may have minimal stiffness of gait or be unable to stand or walk.
Usually, tendon reflexes are brisk in the legs and arms, and ankle clonus may be present. Occasional children with absent or diminished ankle tendon reflex have an associated axonal neuropathy. Increased reflexes are usually the only sign of involvement of the arms. Vibratory and position sense are diminished in half of patients. Urinary symptoms, usually in the form of frequency and urgency, and pes cavus deformities each occur in one-third of affected children.
Diagnosis
Familial spastic paraplegia is difficult to diagnose in the absence of a family history, and then becomes a diagnosis of exclusion. This is especially true in childhood in whom dominant transmission is usual. MRI of the brain and spinal cord is usually normal. The differential diagnosis includes multiple sclerosis, structural abnormalities involving the spinal cord, B12 deficiency, adrenomyeloneuropathy and other leukodystrophies, and dopa-responsive dystonia. The diagnosis of HSP is suspect in any child with very slowly progressive spastic paraplegia. Laboratory studies are not helpful except to exclude other conditions such as adrenoleukodystrophy and argininemia. DNA based diagnosis is now available for almost all subtypes.
Management
Several centers use botox injections to relieve spasticity. Many children require ankle-foot orthoses to improve gait. Treatment is not available for the underlying condition.
Autosomal Recessive Inheritance
Autosomal recessive inheritance of hereditary spastic paraplegia may be pure or complicated. Both forms are genetically heterogeneous. Autosomal recessive cases account for 15–20 % of the total ( ).
Clinical Features
Spastic paraplegia may begin during infancy or be delayed until adolescence. Involvement of other neurological systems follows. The common associated features, alone or in combination, include cerebellar dysfunction, pseudobulbar palsy, sensory neuropathy, and pes cavus.
Children with sensory neuropathy lose the once hyperactive tendon reflexes in the legs. Some show developmental delay and never achieve bladder control. When sensory loss is progressive, the symptoms resemble those of familial sensory neuropathies described in Chapter 9 . The outcome varies from mild disability to wheelchair dependence.
Diagnosis
In the absence of a family history, the course of disease may suggest cerebral palsy until the progressive nature of the spasticity is recognized. Sensory neuropathy with mutilation of digits may lead to the erroneous diagnosis of syringomyelia. Laboratory tests are useful only to exclude other diagnoses. Argininemia, a treatable cause of autosomal recessive progressive spastic paraplegia, is a consideration ( ).
Management
No treatment is available for the underlying defect, but the sensory neuropathy requires supportive care (see Chapter 9 ).
Infections
Primary myelitis from acquired immune deficiency syndrome is uncommon in children and not discussed in this section.
Diskitis (Disk Space Infection)
Disk space infection is a relatively uncommon disorder of childhood in which one disk space is infected secondary to subacute osteomyelitis of the adjacent vertebral bodies. The cause is bacterial infection. Staphylococcus aureus is the organism most often grown on culture of disk material removed by needle biopsy and is probably the major cause. Blood cultures are often negative, likely because the infection is subacute. Biopsy is typically unnecessary.
Clinical Features
The initial feature is either difficulty walking or back pain. Difficulty walking occurs almost exclusively in children less than 3 years of age. The typical child has a low-grade or no fever, is observed to be limping, and may refuse to stand or walk. This symptom complex evolves over 24 to 48 hours. Affected children prefer to lie on their sides rather than to rest supine, resist standing, and then seem uncomfortable and walk with a shuffling gait. Examination shows loss of lumbar lordosis and absolute resistance to flexion of the spine. The hips or back are sometimes tender.
Pain as an initial feature occurs more often after 3 years of age. The pain may be vertebral or rarely abdominal. When abdominal, the pain gradually increases in intensity and may radiate from the epigastrium to the umbilicus or pelvis. Abdominal pain in association with low-grade fever and an elevated peripheral white blood cell count invariably suggests the possibility of appendicitis or other intra-abdominal disease. Fortunately, abdominal pain is the least common presenting feature.
Back pain is the most common complaint. Older children may indicate a specific area of pain and tenderness. Younger children may have only an abnormal posture intended to splint the painful area. Back pain usually leads to prompt diagnosis because attention immediately directs to the spine. Examination reveals loss of lumbar lordosis and decreased movement of the spine, especially flexion.
Diagnosis
Disk space infection is a consideration in all children who have sudden back pain or refuse to walk, and in whom there are no specific neurological abnormalities. Strength, tone, and tendon reflexes in the legs are normal. Radiographs of the spine reveal narrowing of the affected intervertebral space, most often in the lumbar region but sometimes as high as the C5 to C6 positions. MRI is the best method to demonstrate inflammation within the disk. It shows osteomyelitis of the surrounding vertebrae as well as of the disk space ( Figure 12-2 ).
