Practice Essentials
Idiopathic intracranial hypertension (IIH; also known as pseudotumor cerebri [PTC] or benign intracranial hypertension [BIH]) is characterized by signs and symptoms of increased intracranial pressure (ICP) in the absence of a space-occupying lesion. [1]
IIH mainly occurs among obese women of childbearing age. [2] Although its prevalence among the pediatric population is not known, it is not uncommon among the young.
Signs and symptoms
Common signs and symptoms of idiopathic intracranial hypertension (IIH) in the young include headache, vomiting, blurred vision, and diplopia. [3, 4] Other less common side affects include retro-orbital, neck, and back pain. [5]
Diagnosis
The diagnosis of IIH is made after other causes of increase ICP)—such as mass lesions (particularly those involving the midline [eg, medulloblastoma], and causes of recurrent or chronic headache (eg, migraine and hydrocephalus) have been excluded.
Magnetic resonance imaging (MRI) of the brain with magnetic resonance venography (MRV) is preferred. In children, computed tomography (CT) of the head should be avoided when possible to minimize radiation exposure.
Management
Indications for treatment of IIH include vision loss, moderate to severe papilledema, and a persistent headache. Asymptomatic patients with mild papilledema do not require treatment and should undergo routine ophthalmological exam. [5] Sometimes, the symptoms of IIH resolve with the initial diagnostic lumbar puncture. If this occurs, no further medical treatment is required. When medical treatment is required, most children respond to medications such as steroids, acetazolamide, furosemide, or topiramate.
The main indications for surgical intervention to treat IIH are deterioration in vision and incapacitating headaches despite aggressive medical management. There are 2 main surgical approaches to the treatment of pediatric IIH: optic nerve sheath fenestration and CSF diversion (typically, lumboperitoneal shunting). [6]
Background
Idiopathic intracranial hypertension (IIH; also known as pseudotumor cerebri [PTC] or benign intracranial hypertension [BIH]) is characterized by signs and symptoms of increased intracranial pressure (ICP) in the absence of a space-occupying lesion. [1]
IIH mainly occurs among obese women of childbearing age. [2] Although its prevalence among the pediatric population is not known, it is not uncommon among the young. In children younger than 6 years, a specific cause of intracranial hypertension can usually be identified. Primary or idiopathic cases of intracranial hypertension are usually seen after age 11 years.
Prepubertal children with PTC have a lower incidence of obesity compared with adults, and there is no sex predilection. Similar to adult patients, children are at risk for the development of permanent visual loss. [7]
Children with IIH usually complain of headaches and may have vomiting, blurred vision, and horizontal diplopia. The headaches are diffuse, worse at night, and often aggravated by sudden movement. Less common complaints include irritability, transitory visual obscurations, dizziness, and tinnitus.
As in adults, treatment is designed to reduce ICP and preserve vision. (See Idiopathic Intracranial Hypertension.)
Although IIH has been recognized for over a century, the need remains for prospectively collected data to promote a better understanding of the etiology, risk factors, evaluative methods, and effective treatments for children with this syndrome. [8, 9]
Pathophysiology
The precise mechanism of the ICP elevation in IIH is unknown. Factors that may play an important role in the pathogenesis include excessive cerebrospinal fluid (CSF) and extracellular edema, increased venous sinus pressure, and defective CSF absorption. There is some evidence for each of these factors in the literature, and it is likely that more than 1 mechanism is responsible.
The importance of venous sinus pressure is seen in children who develop increased ICP after thrombosis of 1 or more dural sinuses, usually secondary to otitis or mastoiditis. Studies of pediatric IIH patients have shown elevated sagittal sinus pressure, which could lead to resistance to CSF absorption at the arachnoid villi. Through radioisotope cisternography, affected patients have also been found to have a 3- to 5-fold decrease in CSF absorption.
A number of studies of IIH patients have suggested the presence of excessive “brain water” (ie, an edematous brain). Although the finding is somewhat controversial, histologic evidence of vasogenic brain edema has been observed in biopsy specimens from a small number of patients. Increased intracranial blood volume has also been shown in several studies, and excessive white matter water has been reported on magnetic resonance imaging (MRI).
Malm et al used a constant pressure infusion method to study CSF dynamics in 17 patients older than 15 years and found reduced conductance to CSF flow; however, the reduction was insufficient to explain the increase in CSF pressure. [10] No significant difference in the rate of CSF production was noted between IIH patients and control subjects. The investigators also noted that sagittal sinus pressure was elevated in more than half of their patients, which was attributed to increased brain water content causing compression of venous outflow.
Using sophisticated magnetic resonance (MR) venography, Farb et al found a high incidence of transverse and sigmoid sinus stenoses in patients with IIH as compared with control subjects. [11] Other studies indicated that increased ICP can cause a collapse of the walls of the transverse sinus, which suggests that venous sinus stenosis is a secondary phenomenon.
Hormonal influences appear to play some role in the pathogenesis of IIH. In postpubertal patients, the condition is distinctly more common among females. Obesity is a well-recognized risk factor. [9] Childhood obesity is strongly associated with an increased risk of pediatric IIH in adolescents. [12] The current childhood obesity epidemic is likely to lead to increased morbidity from IIH, particularly among extremely obese, white, non-Hispanic, teenage girls. Vigilant screening of these at-risk individuals may lead to earlier detection and opportunity for treatment of IIH. [13, 14, 15, 16]
Studies have suggested associations of IIH with nonspecific infections, minor head injury, withdrawal from corticosteroid therapy, vitamin A, [17] acne treatment, and certain antibiotics (eg, tetracyclines). On rare occasions, severe iron deficiency anemia, endocrinopathies, and CO2 retention have been implicated.
Etiology
Of the many conditions that have been associated with IIH in children, none has been convincingly shown to be causative, except perhaps for certain medications. [18] The following medications may be associated with IIH:
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Retinoic acid
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Antibiotics - Tetracycline, nitrofurantoin, fluoroquinolones
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Hormones - Steroid use or withdrawal (even topical use), oral contraceptives, L-thyroxine
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Vitamin A [17]
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Lithium [19]
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Immunizations - In 1 case report, IIH developed in a 7-month-old after diphtheria-tetanus-pertussis (DTP) immunization
Refeeding and weight gain in nutritionally deprived children (eg, children with cystic fibrosis) may be associated with IIH. Endocrine abnormalities potentially associated with IIH include adrenal dysfunction and Addison disease, hypothyroidism or hyperthyroidism, hypocalcemia due to vitamin D deficiency or hypoparathyroidism, and panhypopituitarism.
Obstructive sleep apnea has been shown to increase intracranial pressure, and proposed to be a secondary cause of intracranial hypertension. [20]
Epidemiology
Epidemiologic studies of IIH in US children are not available. The annual incidence among all adults in the United States appears to be 0.9 per 100,000 population; that among US females, 3.5 per 100,000; and that among obese US females, 13–19 per 100,000. An incidence of 1.7 per 100,000 was reported in Libya.
IIH has a strong predilection exists for postpubertal women. Although IIH is most common among women of childbearing age, it has been reported in early infancy. Typically, a specific cause of intracranial hypertension can be identified among young children. Some studies have suggested that urban African Americans may be at increased risk.
Prognosis
The natural history of IIH in childhood is poorly understood. Some children respond to initial lumbar puncture alone. Visual loss can occur at any point in the disease, and no predictive factors have been reliably associated with this complication. Patient and parental education as to the seriousness of permanent visual loss should be given. Early intervention in rapidly declining visual function is crucial to improve the long-term visual outcome.
The mortality associated with IIH is no higher than that seen in the general population. The only major morbidity is visual loss. The incidence of visual loss among children with IIH is unknown. Among all patients, some degree of permanent visual loss occurs in approximately 10% of cases. In a study by Soiberman et al, pediatric patients with IIH have a favorable visual outcome in terms of both visual acuity and visual field. If there is any recurrence, it is most likely to occur during the first 18 months after diagnosis. [21]
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For IIH to be diagnosed, brain scans (such as MRI) must be performed to ensure there is no underlying cause for the increased pressure around the brain
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Left optic disc with moderate chronic papilledema in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Paton lines (arc-shaped retinal wrinkles concentric with disc margin) are seen along temporal side of inferior pole of disc.
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Right optic disc with postpapilledema optic atrophy in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Diffuse pallor of disc and absence of small arterial vessels on surface are noted, with very little disc elevation. Disc margin at upper and lower poles and nasally is obscured by some residual edema in nerve fiber layer and gliosis that often persists even after all edema has resolved.
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Most common early visual field defect in papilledema as optic nerve develops optic atrophy is inferior nasal defect, as shown in left eye field chart (left side of figure). Shaded area indicates defective portion of field. Note sharp line of demarcation between defective lower nasal quadrant and normal upper nasal quadrant along horizontal midline. This is characteristic of early papilledema optic atrophy and is referred to as nasal step or inferonasal step.
