Increased Intracranial Pressure

The presenting complaint when dealing with increased intracranial pressure ( Box 4-1 ) varies with age. Infants may present with bulging fontanelle, macrocephaly or failure to thrive. Older children often present with headache, emesis, diplopia or change in mentation. The basis of referral for some children is the detection of disc edema during an eye examination. Some conditions causing increased intracranial pressure are discussed elsewhere in this book (see Chapter 2, Chapter 3, Chapter 10, Chapter 15 ). This chapter is restricted to conditions in which symptoms of increased intracranial pressure are initial and prominent features. The timely management of increased intracranial pressure prevents secondary brain insult, regardless of the original cause, which is often a primary central nervous sytem (CNS) process (infection, abscess, tumor, infarct, others). When treating increased intracranial pressure the goal is to reduce the pressure while maintaining adequate cerebral perfusion.

BOX 4-1

In Infants

  • Bulging fontanelle

  • Failure to thrive

  • Impaired upward gaze (setting sun sign)

  • Large head (see Chapter 18 )

  • Shrill cry

  • Split sutures

In Children

Features of Increased Intracranial Pressure

Pathophysiology

Normal intracranial pressure in the resting state is approximately 10 mmHg (136 mmH 2 O). Pressures greater than 20 mmHg are abnormal. When the cranial bones fuse during childhood, the skull is a rigid box enveloping its content. Intracranial pressure is then the sum of the individual pressures exerted by the brain, blood, and cerebrospinal fluid (CSF). An increase in the volume of any one component requires an equivalent decrease in the size of one or both of the other compartments if intracranial pressure is to remain constant. Because the provision of oxygen and nutrients to the brain requires relatively constant cerebral blood flow, the major adaptive mechanisms available to relieve pressure are the compressibility of the brain and the rapid reabsorption of cerebrospinal fluid (CSF) by arachnoid villi. Infants and young children, in whom the cranial bones are still unfused, have the additional adaptive mechanism of spreading the cranial bones apart and bulging of the anterior fontanelle to increase cranial volume.

Cerebrospinal Fluid

The choroid plexus accounts for at least 70 % of CSF production, and the transependymal movement of fluid from the brain to the ventricular system accounts for the remainder. The average volumes of CSF are 90 mL in children 4 to 13 years old and 150 mL in adults. The rate of formation is approximately 0.35 mL/min or 500 mL/day. Approximately 14% of total volume turns over every hour. The rate at which CSF forms remains relatively constant and declines only slightly as CSF pressure increases. In contrast, the rate of absorption increases linearly as CSF pressure exceeds 7 mmHg. At a pressure of 20 mmHg, the rate of absorption is three times the rate of formation.

Impaired absorption, not increased formation, is the usual mechanism of progressive hydrocephalus. Choroid plexus papilloma is the only pathological process in which formation sometimes can overwhelm absorption. However, even in cases of choroid plexus papillomas, obstruction of the CSF flow rather than overproduction may be the cause of hydrocephalus. When absorption is impaired, efforts to decrease the formation of CSF are not likely to have a significant effect on volume and intracranial pressure.

Cerebral Blood Flow

Systemic arterial pressure is the primary determinant of cerebral blood flow. Normal cerebral blood flow remains remarkably constant from birth to adult life and is generally 50–60 mL/min/100 g brain weight. The autonomic innervation of blood vessels on the surface and at the base of the brain is richer than vessels of any other organ. These nerve fibers allow the autoregulation of cerebral blood flow. Autoregulation refers to a buffering effect by which cerebral blood flow remains constant despite changes in systemic arterial perfusion pressure. Alterations in the arterial blood concentration of carbon dioxide have an important effect on total cerebral blood flow. Hypercarbia dilates cerebral blood vessels and increases blood flow, whereas hypocarbia constricts cerebral blood vessels and decreases flow. Alterations in blood oxygen content have the reverse effect, but are less potent stimuli for vasoconstriction or vasodilation than are alterations in the blood carbon dioxide concentration.

Cerebral perfusion pressure is the difference between mean systemic arterial pressure and intracranial pressure. Reducing systemic arterial pressure or increasing intracranial pressure reduces perfusion pressure to dangerous levels. The autoregulation of the cerebral vessels is lost when cerebral perfusion pressure decreases to less than 50 cmH 2 O or in the presence of severe acidosis. Arterial vasodilation or obstruction of cerebral veins and venous sinuses increases intracranial blood volume. Increased intracranial blood volume, similar to increased CSF volume, results in increased intracranial pressure.

Cerebral Edema

Cerebral edema is an increase in the brain’s volume caused by an increase in its water and sodium content. Increased intracranial pressure results from either localized or generalized cerebral edema. The categories of cerebral edema are vasogenic, cytotoxic, or interstitial.

Increased capillary permeability causes vasogenic edema; this occurs with brain tumor, abscess, and infection, and to a lesser degree with trauma and hemorrhage. The fluid is located primarily in the white matter and responds to treatment with corticosteroids. Osmotic agents have no effect on vasogenic edema, but they reduce total intracranial pressure by decreasing normal brain volume. Cytotoxic edema, characterized by swelling of neurons, glia, and endothelial cells, constricts the extracellular space. The usual causes are hypoxia and ischemia. Corticosteroids do not decrease this type of edema, but osmotic agents may relieve intracranial pressure by reducing brain volume.

Transependymal movement of fluid causes interstitial edema from the ventricular system to the brain; this occurs when CSF absorption is blocked and the ventricles enlarge. The fluid collects chiefly in the periventricular white matter. Agents intended to reduce CSF production, such as acetazolamide, topiramate ( ), and furosemide, may be useful. Corticosteroids and osmotic agents are not effective.

Mass Lesions

Mass lesions, e.g., tumor, abscess, hematoma, arteriovenous malformation, increase intracranial pressure by occupying space at the expense of other intracranial compartments, provoking cerebral edema, blocking the circulation and absorption of CSF, increasing blood flow, and obstructing venous return.

Symptoms and Signs

The clinical features of increased intracranial pressure depend on the child’s age and the rate at which pressure increases. Newborns and infants present a special case because expansion of skull volume allows partial venting of increased pressure. The rate of intracranial pressure increase is important at all ages. Intracranial structures accommodate slowly increasing pressure remarkably well, but sudden changes are intolerable and result in some combination of headache, personality change, and states of decreasing consciousness.

Increased Intracranial Pressure in Infancy

Measurement of head circumference and palpation of the anterior fontanelle are readily available methods of assessing intracranial volume and pressure rapidly. The measure of head circumference is the greatest anteroposterior circumference. Normal standards are different for premature and full-term newborns. Normal head growth in a term newborn is 2 cm/month for the first 3 months, 1 cm/month for the second 3 months, and 0.5 cm/month for the next 6 months. Excessive head growth is a major feature of increased intracranial pressure throughout the first year up to 3 years of age. Normal head growth does not preclude the presence of increased intracranial pressure; for example, in posthemorrhagic hydrocephalus, considerable ventricular dilation precedes any measurable change in head circumference by compressing the brain parenchyma.

The palpable tension of the anterior fontanelle is an excellent measure of intracranial pressure. In a quiet infant, a fontanelle that bulges above the level of the bone edges and is sufficiently tense to cause difficulty in determining where bone ends and fontanelle begins is abnormal and indicates increased intracranial pressure. A full fontanelle, which is clearly distinguishable from the surrounding bone edges, may indicate increased intracranial pressure, but alternate causes are crying, edema of the scalp, subgaleal hemorrhage, and extravasation of intravenous fluids. The normal fontanelle clearly demarcates from bone edges, falls below the surface, and pulsates under the examining finger. Although the size of the anterior fontanelle and its rate of closure are variable, increased intracranial pressure should be suspected when separation of the metopic and coronal sutures is sufficient to accomodate a fingertip.

The infant experiences lethargy, vomiting, and failure to thrive when cranial suture separation becomes insufficient to decompress increased intracranial pressure. Sixth cranial nerve palsies, impaired upward gaze (setting sun sign), and disturbances of blood pressure and pulse may ensue. Optic disc edema is uncommon.

Increased Intracranial Pressure in Children

Headache

Headache is a common symptom of increased intracranial pressure at all ages. Traction and displacement of intracranial arteries are the major causes of headache from increased intracranial pressure (see Chapter 3 ). As a rule, the trigeminal nerve innervates pain from supratentorial intracranial vessels, and referral of pain is to the eye, forehead, and temple. In contrast, cervical nerves innervate infratentorial intracranial vessels, and referral of pain is to the occiput and neck.

With generalized increased intracranial pressure, as occurs from cerebral edema or obstruction of the ventricular system, headache is generalized and more prominent on awakening and when rising to a standing position. Pain is constant but may vary in intensity. Coughing, sneezing, straining, and other maneuvers, such as Valsalva, that transiently increase intracranial pressure exaggerate headache. The quality of the pain is often difficult to describe. Vomiting in the absence of nausea, especially on arising in the morning, is often a concurrent feature. In the absence of generalized increased intracranial pressure, localized, or at least unilateral, headache can occur if a mass causes traction on contiguous vessels.

In children younger than 10 years old, separation of sutures may relieve symptoms of increased intracranial pressure temporarily. Such children may have a symptom-free interval of several weeks after weeks or months of chronic headache and vomiting. The relief of pressure is temporary, and symptoms eventually return with their prior intensity. An intermittent course of symptoms should not direct attention away from the possibility of increased intracranial pressure.

An individual who was previously well and then experienced abrupt onset, intense headache probably has suffered a subarachnoid hemorrhage. A small hemorrhage may not cause loss of consciousness but still produces sufficient meningeal irritation to cause intense headache and some stiffness of the neck. Fever may be present.

Diplopia and Strabismus

Paralysis or paresis of one or both abducens nerves is a common feature of generalized increased intracranial pressure and may be a more prominent feature than headache in children with idiopathic intracranial hypertension (pseudotumor cerebri).

Optic Disc Edema

Optic disc edema (“papilledema”) is passive swelling of the optic disc caused by increased intracranial pressure ( Box 4-2 ). Extension of the arachnoid sheath of the optic nerve to the retina is essential for the of optic disc edema. This extension does not occur in a small percentage of people, and they can have severe increased intracranial pressure without disc edema. The edema is usually bilateral and when unilateral suggests a mass lesion behind the affected eye. Early disc edema is asymptomatic. Only with advanced papilledema does transitory obscuration of vision occur. Preservation of visual acuity differentiates papilledema from primary optic nerve disturbances, such as optic neuritis, in which visual acuity is always profoundly impaired early in the course (see Chapter 16 ).

BOX 4-2

  • Congenital disk elevation

  • Increased intracranial pressure

  • Ischemic neuropathy

  • Optic glioma

  • Optic nerve drusen

  • Papillitis

  • Retrobulbar mass

Differential Diagnosis of a Swollen Disk

The observation of papilledema in a child with headache or diplopia confirms the diagnosis of increased intracranial pressure. The diagnosis of papilledema is not always easy, however, and congenital variations of disc appearance may confuse the issue. The earliest sign of papilledema is loss of spontaneous venous pulsations in the vessels around the disc margin. Spontaneous venous pulsations occur in approximately 80 % of normal adults, but the rate is closer to 100 % in children. Spontaneous venous pulsations cease when intracranial pressure exceeds 200 mmH 2 O. Papilledema is not present if spontaneous venous pulsations are present, no matter how obscure the disc margin may appear to be. Conversely, when spontaneous venous pulsations are lacking in children, one should suspect papilledema even though the disc margin is flat and well visualized.

As edema progresses, the disc swells and is raised above the plane of the retina, causing obscuration of the disc margin and tortuosity of the veins ( Figure 4-1 ). Associated features include small flame-shaped hemorrhages and nerve fiber infarcts known as cotton wool. If the process continues, the retina surrounding the disc becomes edematous so that the disk appears greatly enlarged ( Figure 4-2 ), and retinal exudates radiate from the fovea. Eventually the hemorrhages and exudates clear, but optic atrophy ensues, and blindness may be permanent. Even if increased intracranial pressure is relieved during the early stages of disc edema, 4 to 6 weeks is required before the retina appears normal again.

FIGURE 4-1
Acute papilledema. The optic disk is swollen, and peripapillary nerve fiber layer hemorrhages are evident.
FIGURE 4-2
Established papilledema. The optic disk is elevated, and opacification of the nerve fiber layer shows around the disk margin and retinal folds (Paton lines) temporally.

Congenitally elevated discs, usually caused by hyaline bodies (drusen) within the nerve head, give the false impression of papilledema. The actual drusen are not observable before age 10, and only the elevated nerve head is apparent. Drusen continue to grow and can be seen in older children and in their parents ( Figure 4-3 ). Drusen are an autosomal dominant trait and occur more often in Europeans than other ethnic groups. Spontaneous venous pulsations differentiate papilledema from anomalous nerve head elevations. Their presence excludes papilledema.

FIGURE 4-3
Drusen. The disk margin is indistinct, the physiological cup is absent, and yellowish globular bodies are present on the surface.

Herniation Syndromes

Increased intracranial pressure may cause portions of the brain to shift from their normal location into other compartments, compressing structures already occupying that space. These shifts may occur under the falx cerebri, through the tentorial notch, and through the foramen magnum ( Box 4-3 ).

BOX 4-3

Unilateral (Uncal) Transtentorial Herniation

  • Declining consciousness

  • Increased blood pressure, slow pulse

  • Dilated and fixed pupil

  • Homonymous hemianopia

  • Respiratory irregularity

  • Decerebrate rigidity

Bilateral (Central) Transtentorial Herniation

  • Decerebrate or decorticate rigidity

  • Declining consciousness

  • Impaired upward gaze

  • Irregular respiration

  • Pupillary constriction or dilation

Cerebellar (Downward) Herniation

  • Declining consciousness

  • Impaired upward gaze

  • Irregular respirations

  • Lower cranial nerve palsies

  • Neck stiffness or head tilt

Herniation Syndromes

Increased intracranial pressure is a relative contraindication for lumbar puncture. The change in fluid dynamics causes herniation in certain circumstances. The hazard is greatest when pressure between cranial compartments is unequal. This prohibition is relative, and early lumbar puncture is the rule in infants and children with suspected infections of the nervous system despite the presence of increased intracranial pressure. In other situations, lumbar puncture is rarely essential for diagnosis, but usually accomplished safely in the absence of papilledema. The following computed tomography (CT) criteria define people at increased risk of herniation after lumbar puncture:

  • Lateral shift of midline structures

  • Loss of the suprachiasmatic and basilar cisterns

  • Obliteration of the fourth ventricle

  • Obliteration of the superior cerebellar and quadrigeminal plate cisterns.

Falx Herniation

Herniation of one cingulate gyrus under the falx cerebri is more common in the presence of one enlarged hemisphere. The major feature is compression of the internal cerebral vein and the anterior cerebral artery, resulting in still greater increased intracranial pressure because of reduced venous outflow and arterial infarction.

Unilateral (Uncal) Transtentorial Herniation

The tentorial notch allows structures to pass from the posterior to the middle fossa. The brainstem, the posterior cerebral artery, and the third cranial nerve are its normal components. Unilateral transtentorial herniation characteristically occurs when enlargement of one temporal lobe causes the uncus or hippocampus to bulge into the tentorial notch. Falx herniation is usually an associated feature. Because considerable intracranial pressure is required to cause such a shift, consciousness decreases even before the actual herniation. It declines continuously as the brainstem com. Direct pressure on the oculomotor nerve causes ipsilateral dilation of the pupil; sometimes dilation of the contralateral pupil occurs because the displaced brainstem compresses the opposite oculomotor nerve against the incisura of the tentorium. Contralateral homonymous hemianopia occurs (but is impossible to test in an unconscious patient) because of compression of the ipsilateral posterior cerebral artery. With further pressure on the midbrain, both pupils dilate and fix, respirations become irregular, decerebrate posturing is noted, and death results from cardiorespiratory collapse.

Bilateral (Central) Transtentorial Herniation

Central herniation usually is associated with generalized cerebral edema. Both hemispheres displace downward, pushing the diencephalon and midbrain caudad through the tentorial notch. The diencephalon becomes edematous, and the pituitary stalk is avulsed. The clinical features are states of decreasing consciousness, pupillary constriction followed by dilation, impaired upward gaze, irregular respiration, disturbed control of body temperature, decerebrate or decorticate posturing, and death.

Cerebellar Herniation

Increased pressure in the posterior fossa may cause upward herniation of the cerebellum through the tentorial notch or downward displacement of one or both cerebellar tonsils through the foramen magnum. Upward displacement causes compression of the midbrain, resulting in impairment of upward gaze, dilated or fixed pupils, and respiratory irregularity. Downward cerebellar herniation causes compression of the medulla, resulting in states of decreasing consciousness, impaired upward gaze, and lower cranial nerve palsies. One of the earliest features of cerebellar herniation into the foramen magnum is neck stiffness or head tilt in an effort to relieve the pressure by enlarging the surface area of the foramen magnum.

Medical Treatment

Several measures to lower increased intracranial pressure are available, even in circumstances in which surgical intervention is required ( Box 4-4 ).

BOX 4-4

  • Corticosteroids

  • Elevation of head

  • Hyperosmolality

    • Glycerol

    • Hypertonic saline

    • Mannitol

  • Hyperventilation

  • Hypothermia

  • Pentobarbital coma

Medical Measures to Decrease Intracranial Pressure

Monitoring Intracranial Pressure

Severe head trauma is the usual reason for continuous monitoring of intracranial pressure in children. Despite advances in technology, the effect of pressure monitoring on the outcome in medical diseases associated with increased intracranial pressure is questionable. It has no value in children with hypoxic-ischemic encephalopathies and has marginal value in children with other kinds of encephalopathies.

Head Elevation

Elevating the head of the bed 30–45° above horizontal improves jugular venous drainage and decreases intracranial pressure. Systemic blood pressure remains unchanged, resulting in increased cerebral perfusion.

Homeostasis

Maintain normal glucose. Both hypo- and hyperglycemia may cause further insult. Hyperglycemia may increase oxidative stress. Maintain adequate oxygenation (95 %) and CO 2 (35–45 mmHg). Avoid hypotension, and maintain systolic pressure at least above the 5th percentile for age; permissive hypertension is often preferred. Prevent hyponatremia and maintain osmolalities between 300 and 320 mOsml/L to decrease possible edema with hyponatremia or decreased osmolality. Maintain normal body temperature, as every 1°C increases brain metabolism by 5 %. Prevent seizures as they may further increase intracranial pressure and brain metabolism. Pain and agitation management are important to prevent further elevations in intracranial pressure; however, sedation should not compromise blood pressure as decrements may result in decreased cerebral perfusion ( ).

Hyperventilation

Children with Glasgow Scale scores of less than 8 should have intubation to maintain oxygen saturations above 95 % and end tidal carbon dioxide between 35 and 40 mmHg. Intracranial pressure decreases within seconds of the initiation of hyperventilation. The mechanism is vasoconstriction resulting from hypocarbia. The goal is to lower the arterial pressure of carbon dioxide to 25–30 mmHg. Ischemia may result from further or prolonged reductions. Avoid hyperventilation in patients with head trauma. The use of hyperventilation is only a transient benefit and should always be followed by immediate neurosurgical consultation ( ).

Osmotic Diuretics

Mannitol is the osmotic diuretic most widely used in the United States. A 20 % solution of mannitol, 0.25 g to 1 g/kg infused intravenously over 15 minutes, exerts its beneficial effects as a plasma expander and as an osmotic diuretic. Hypertonic saline causes similar vascular changes to mannitol. The typical dosage is 5–10 mL/kg of 3 % hypertonic saline solution given over 5 to 10 minutes ( ). Excretion is by the kidneys, and large doses may cause renal failure, especially when using nephrotoxic drugs concurrently. Maintain serum osmolarity at less than 320 mOsm and adequate intravascular volume.

Corticosteroids

Corticosteroids, such as dexamethasone, are effective in the treatment of vasogenic edema. The intravenous dosage is 0.1–0.2 mg/kg every 6 hours. Onset of action is 12 to 24 hours; peak action may be longer. The mechanism is uncertain. Cerebral blood flow is not affected. Corticosteroids are most useful for reducing edema surrounding mass lesions and are not useful in the treatment of edema secondary to head injury.

Hypothermia

Hypothermia decreases cerebral blood flow and frequently is used concurrently with pentobarbital coma. Body temperature maintained between 27°C and 31°C is ideal. The gain of using hypothermia in addition to other measures that decrease cerebral blood flow is uncertain.

Pentobarbital Coma

Barbiturates reduce cerebral blood flow, decrease edema formation, and lower the brain’s metabolic rate. These effects do not occur at anticonvulsant plasma concentrations but require brain concentrations sufficient to produce a burst-suppression pattern on the electroencephalogram. Barbiturate coma is particularly useful in patients with increased intracranial pressure resulting from disorders of mitochondrial function, such as Reye syndrome. Pentobarbital is preferred to phenobarbital (see Chapter 1 ).

Hydrocephalus

Hydrocephalus is a condition marked by an excessive volume of intracranial CSF. It is termed communicating or noncommunicating, depending on whether or not the CSF communicates between the ventricular system and the subarachnoid space. Congenital hydrocephalus occurs in approximately 1:1000 births. It is generally associated with other congenital malformations, and the causes are genetic disturbances or intrauterine disorders, such as infection and hemorrhage. Often, no cause is determined. Congenital hydrocephalus is discussed in Chapter 18 because its initial feature is usually macrocephaly.

The causes of acquired hydrocephalus are brain tumor, intracranial hemorrhage, or infection. Solid brain tumors generally produce hydrocephalus by obstructing the ventricular system, whereas nonsolid tumors, such as leukemia, impair the reabsorptive mechanism in the subarachnoid space.

Intracranial hemorrhage and infection may produce communicating and noncommunicating hydrocephalus and may increase intracranial pressure through the mechanisms of cerebral edema and impaired venous return. Because several factors contribute to increased intracranial pressure, acquired hydrocephalus is discussed by cause in the sections that follow.

Brain Tumors

Primary tumors of the posterior fossa and middle fossa are discussed in Chapter 10 , Chapter 15 , Chapter 16 ( Box 4-5 ). This section discusses tumors of the cerebral hemispheres. Supratentorial tumors comprise approximately half of brain tumors in children. They occur more commonly in children younger than 2 years old and adolescents.

BOX 4-5

Hemispheric Tumors

  • Choroid plexus papilloma

  • Glial tumors

    • Astrocytoma

    • Ependymoma

    • Oligodendroglioma

    • Primitive neuroectodermal tumors

  • Pineal region tumors

    • Pineal parenchymal tumors

      • Pineoblastoma

      • Pineocytoma

    • Germ cell tumors

      • Embryonal cell carcinoma

      • Germinoma

      • Teratoma

    • Glial tumors

      • Astrocytoma

      • Ganglioglioma

  • Other tumors

    • Angiomas

    • Dysplasia

    • Meningioma

    • Metastatic tumors

Middle Fossa Tumors

Posterior Fossa Tumors

Brain Tumors in Children

Choroid Plexus Tumors

Choroid plexus tumors arise from the epithelium of the choroid plexus of the cerebral ventricles. They represent only 2–4 % of all pediatric brain tumors, but 10–20 % of tumors that develop in infancy. Three histological variants exist: choroid plexus papillomas, atypical papillomas, and choroid plexus carcinomas. Choroid plexus papillomas are five times more common than choroid plexus carcinoma. Choroid plexus tumors usually are located in one lateral ventricle, but also may arise in the third ventricle.

Clinical Features

Onset is usually during infancy, and the tumor may be present at birth. The main features are those of increased intracranial pressure from hydrocephalus. Communicating hydrocephalus may result from excessive production of CSF by the tumor, but noncommunicating hydrocephalus caused by obstruction of the ventricular foramen is the rule. If the tumor is pedunculated, its movement may cause intermittent ventricular obstruction by a ball-valve mechanism. The usual course is one of rapid progression, with only a few weeks from first symptoms to diagnosis.

Infants with choroid plexus tumors usually have macrocephaly and are thought to have congenital hydrocephalus. Older children have nausea, vomiting, diplopia, headaches, and weakness. Papilledema is the rule.

Diagnosis

Multilobular, calcified, contrast-enhancing intraventricular masses are characteristic of choroid plexus tumors. Because affected children show clear evidence of increased intracranial pressure, CT is usually the first test performed. The tumor is located within one ventricle as a mass of increased density with marked contrast enhancement. Hydrocephalus of one or both lateral ventricles is present. Choroid plexus papillomas are vascular and many tumors bleed spontaneously. The spinal fluid may be xanthochromic or grossly bloody. The protein concentration in the CSF is usually elevated.

Management

The choroid plexus receives its blood supply from the anterior and posterior choroidal arteries, branches of the internal carotid artery, and the posterior cerebral artery. The rich vascular network within the tumors is a major obstacle to complete surgical removal. Yet the extent of surgical resection is the single most important factor that determines the prognosis of a choroid plexus papilloma.

Preliminary evidence suggests that choroid plexus carcinomas are chemosensitive tumors. The role of adjuvant radiation is controversial. The indications for radiation are age younger than age 3 years, subtotal resection, malignant features within the tumor, or dissemination of the tumor along the neuraxis.

The 5-year survival rate is 50 %, with most deaths occurring within 7 months of surgery. Complete tumor removal completely relieves hydrocephalus without the need of a shunt.

Glial Tumors

Tumors of glial origin constitute approximately 40 % of supratentorial tumors in infants and children. The common glial tumors of childhood in order of frequency are astrocytoma, ependymoma, and oligodendroglioma. A mixture of two or more cell types is the rule. Oligodendroglioma occurs exclusively in the cerebral hemispheres, whereas astrocytoma and ependymoma have either a supratentorial or an infratentorial location. Oligodendroglioma is mainly a tumor of adolescence. These tumors grow slowly and tend to calcify. The initial symptom is usually a seizure rather than increased intracranial pressure.

Astrocytoma

The grading of hemispheric astrocytomas is by histological appearance: low-grade, anaplastic, and glioblastoma multiforme. Low-grade astrocytomas confined to the posterior fossa constitute 12–18 % of all pediatric intracranial tumors and 20–40 % of all brainstem tumors. No gender predilection exists; the peak age at diagnosis is 6 to 10 years. Low-grade astrocytomas are more common than high-grade astrocytomas in children. The incidence of low-grade astrocytomas has increased in recent years because of the widespread availability and use of MRI in the diagnosis of presymptomatic lesions ( ).

Anaplastic tumors and glioblastoma multiforme are high-grade tumors. Glioblastoma multiforme accounts for fewer than 10 % of childhood supratentorial astrocytomas and is more likely to occur in adolescence than in infancy. High-grade tumors may evolve from low-grade tumors.

Clinical Features

The initial features of glial tumors in children depend on location and may include seizures, hemiparesis, and movement disorders affecting one side of the body. Seizures are the most common initial feature of low-grade gliomas. Tumors infiltrating the basal ganglia and internal capsule are less likely to cause seizures than tumors closer to cortical structures. A slow-growing tumor may not cause a mass effect because surrounding neural structures accommodate infiltrating tumors. Such tumors may cause only seizures for several years before causing weakness of the contralateral limbs.

Headache is a relatively common complaint. Pain localizes if the tumor produces focal displacement of vessels without increasing intracranial pressure. A persistent focal headache usually correlates well with tumor location.

The initial features in children with medullary tumors may be progressive dysphagia, hoarseness, ataxia, and hemiparesis. Cervicomedullary tumors cause neck discomfort, weakness or numbness of the hands, and an asymmetric quadriparesis. Midbrain tumors cause features of increased intracranial pressure, diplopia, and hemiparesis.

Symptoms of increased intracranial pressure, generalized headache, nausea, and vomiting are initial features of hemispheric astrocytoma in only one-third of children but are common at the time of diagnosis. Intracranial pressure is likely to increase when rapidly growing tumors provoke edema of the hemisphere. A mass effect collapses one ventricle, shifts midline structures, and puts pressure on the aqueduct. When herniation occurs or when the lateral ventricles are dilated because of pressure on the aqueduct, the early features of headache, nausea, vomiting, and diplopia are followed by generalized weakness or fatigability, lethargy, and declining consciousness.

Papilledema occurs in children with generalized increased intracranial pressure, but macrocephaly occurs in infants. When papilledema is present, abducens palsy is usually an associated symptom. Other neurological findings depend on the site of the tumor and may include hemiparesis, hemisensory loss, or homonymous hemianopia.

Diagnosis

MRI is always preferable to CT when suspecting a tumor. In a CT scan, a low-grade glioma appears as low-density or cystic areas that enhance with contrast material ( Figure 4-4 ). A low-density area surrounding the tumor that does not show contrast enhancement indicates edema.

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Mar 3, 2019 | Posted by in NEUROLOGY | Comments Off on Increased Intracranial Pressure

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