Basics
Description
Diagnostic criteria of idiopathic intracranial hypertension (IIH) include the following:
- Signs and symptoms of increased intracranial pressure (e.g., headache, vomiting, ocular manifestations, and papilledema)
- Elevated cerebrocranial fluid pressure but otherwise normal CSF
- Normal neurologic exam except for papilledema (occasional abducens or other motor cranial neuropathy)
- Normal neuroimaging study (or incidental findings only)
Epidemiology
- Boys and girls are affected equally in childhood; in adulthood, more women than men are affected.
- IIH has been reported in patients as young as 4 months of age, with a median age of 9 years.
Incidence
Estimated to be 0.5/100,000 cases/year for children younger than 18 years old
Risk Factors
Genetics
Sporadic, no clear genetic predisposition, unless related to an underlying hormonal, toxic, or inflammatory condition; no data are available in children.
Pathophysiology
Pathogenesis unknown but may involve decreased CSF absorption owing to arachnoid villi dysfunction or elevated intracranial venous pressure. For example, obesity may lead to increased intra-abdominal, intrathoracic, and cardiac filling pressure, leading to elevated intracranial venous pressure.
Etiology
- Numerous precipitants of IIH have been reported. In adolescents, it is clearly associated with obesity and weight gain but not clearly linked to obesity in children <11 years of age. Many weaker associations may be due to chance.
- IIH is often linked to minocycline, tetracycline, sulfnamides, isotretinoin, and thyroid replacements and to corticosteroid withdrawal. It is also linked to vitamin A deficiency or intoxication, chronic anemia, and hypothyroidism.
Commonly Associated Conditions
- Visual loss due to optic nerve pressure
- Endocrinopathies, exogenous steroids, lead exposure, and therapy involving tetracycline and several other antibiotics may be associated with IIH.
Diagnosis
History
- Headache
- Blurred vision
- Transient visual darkening
- Stiff neck
- Pulsatile tinnitus
- Dizziness
- Infants and young children may present with irritability, somnolence, or ataxia.
- IIH should be considered in any child with chronic headache or unexplained visual changes.
- Directed history for signs of associated endocrinopathy, exposure to antibiotics or steroids, sinus infection, abnormal clotting, or familial tendency for thrombosis or visual disturbance
Physical Exam
- Examination of the fundi is essential.
- Recording baseline visual acuity and visual fields in older children is essential.
- Papilledema is almost always present in older children with IIH.
- Most infants have some degree of papilledema, even with open fontanelles and split sutures.
- 6th cranial nerve (abducens) palsies are common in children with IIH; they were found in 29 of 68 patients in 1 series.
- Facial or other cranial nerve deficits rare
Diagnostic Tests & Interpretation
Lab
- CSF exam including opening pressure; cell count, glucose, and protein are essential and should be normal in IIH.
- CBC and thyroid function tests should be obtained because anemia, hypothyroidism, and hyperthyroidism have rarely been associated with IIH.
- The following may be useful in selected cases:
- ANA test
- ESR
- Urine cortisol
- Serum lead level
- Serologic testing for Lyme disease
Imaging
Cranial CT or MRI should be normal. MRI is recommended because of superior imaging of brainstem, posterior fossa, and venous sinuses. Magnetic resonance venography is strongly suggested to evaluate for venous sinus thrombosis, which can be difficult to distinguish from IIH.
Diagnostic Procedures/Other
- Lumbar puncture manometry, with the patient in a relaxed lateral decubitus position, should show an opening pressure >280 mm H2O.
- Goldmann perimeter visual field testing or computerized visual fields are useful in children >5 years of age to document field deficits and monitor response to therapy.
Differential Diagnosis
Some conditions may cause increased intracranial pressure and be confused with IIH, but the clinical picture and CSF analysis usually permit their distinction.
- Chronic meningitis (e.g., CNS Lyme disease), encephalitis, or cerebral edema (may show minimal changes on neuroimaging with elevated CSF protein levels and little evidence of pleocytosis)
- Cerebral venous sinus thrombosis
- Chronic headache (common) with pseudopapilledema (optic nerve disc drusen)
Treatment
Medication
First Line
- For patients with mild to moderate visual loss, acetazolamide, a carbonic anhydrase inhibitor that decreases CSF production, is the drug of choice.
- The pediatric dosage is 25-100 mg/kg/24 h divided b.i.d.-q.i.d. for the standard form and b.i.d. for the long-acting form (Diamox sequels).
- The initial adult dose is 250 mg q.i.d. or 500 mg b.i.d., increased to 750 mg q.i.d. or 1,500 mg b.i.d. if tolerated.
- If visual loss, papilledema, and symptoms of pressure resolve, acetazolamide dosage can be tapered after 2 months of therapy.
Second Line
Furosemide can be used if acetazolamide is ineffective or has intolerable adverse effects.
Issues for Referral
Follow-up and tapering of acetazolamide should be done in conjunction with a neurologist or neuro-ophthalmologist.
Surgery/Other Procedures
- Serial lumbar punctures are not recommended as standard therapy, although the initial puncture can be useful to relieve symptoms quickly.
- Surgical therapy (e.g., optic nerve sheath fenestration, lumboperitoneal shunt) is indicated for progressive visual loss despite medical therapy and may also be considered as an urgent intervention at presentation depending on degree of visual loss. Optic nerve sheath fenestration may be the preferred surgical treatment, especially in children, because of the high failure rates of lumboperitoneal shunting. High-dose IV steroids and acetazolamide therapy may be used while awaiting surgical therapy.
- Recent studies of stenting in adults with transverse sinus stenosis and a pressure gradient on angiography demonstrated some improvement in visual symptoms and papilledema with variable effects on headache. However, this intervention is controversial and may not be technically feasible in children because of the smaller caliber of their vasculature.
Inpatient Considerations
Initial Stabilization
- The urgency of diagnosis and treatment depends on the severity of visual loss. Recent reports suggest that severe visual loss may progress rapidly, warranting close initial (weekly) tracking of vision and prompt consideration of surgical treatment (see below).
- For patients with no visual loss, removal of possible causative agents may be the only intervention needed, along with treatment of associated conditions (e.g., obesity, anemia, thyroid disease). Consider treatment with acetazolamide (Diamox; see later comment). Headache can be treated symptomatically if needed.
Ongoing Care
Follow-up Recommendations
Patient Monitoring
- Initially, patients should have visual acuity, visual fields, and fundi evaluated weekly or biweekly.
- If vision is stable, monthly visits may be adequate for 3-6 months.
- More frequent follow-up is required for any signs of progressive visual loss.
- IIH can recur. In one pediatric series, nearly 1/4 of patients had recurrence.
- Pitfalls: Children are not exempt from permanent visual loss as a consequence of IIH. Ophthalmologic follow-up is important. Occasional patients, especially adolescents, may experience headache weeks or months after resolution of objective signs of IIH (i.e., even though intracranial pressure has returned to normal).
- IIH may be diagnosed erroneously if
- Pseudopapilledema is mistaken for papilledema. (Pseudopapilledema is apparent optic disc swelling that simulates papilledema but is usually secondary to an underlying benign process. It can be differentiated by an experienced ophthalmologist or neurologist.)
- CSF abnormalities (i.e., isolated increase in protein) are overlooked.
- Clinician fails to identify underlying cerebral venous sinus thrombosis.
Additional Reading
- Avery RA, Licht DJ, Shah SS, et al. CSF opening pressure in children with optic nerve head edema. Neurology. 2011;76(19):1658-1661. [View Abstract]
- Friedman DI, Jacobson DM. Diagnostic criteria for idiopathic intracranial hypertension. Neurology. 2002;59(10):1492-1495. [View Abstract]
- Kesler A, Bassan H. Pseudotumor cerebri-idiopathic intracranial hypertension in the pediatric population. Pediatr Endocrinol Rev. 2006;3(4):387-392. [View Abstract]
- Lim M, Kurian M, Penn A, et al. Visual failure without headache in idiopathic intracranial hypertension. Arch Dis Child. 2005;90(2):206-210. [View Abstract]
- Soiberman U, Stolovitch C, Balcer LJ, et al. Idiopathic intracranial hypertension in children: visual outcome and risk of recurrence. Childs Nerv Syst. 2011;27(11):1913-1918. [View Abstract]
Codes
ICD09
- 348.2 Benign intracranial hypertension
ICD10
- G93.2 Benign intracranial hypertension
SNOMED
- 68267002 Benign intracranial hypertension (disorder)
FAQ
- Q: What are the side effects of acetazolamide?
- A: Side effects of acetazolamide include GI upset, paresthesias, loss of appetite, drowsiness, metabolic acidosis, and renal stones. An alternative is furosemide.
- Q: If IIH occurs on tetracycline, can the patient take penicillin?
- A: Penicillins/cephalosporins have not been reported as a significant cause of IIH.
- Q: Are there any limitations on physical activity?
- A: Activity can be graded entirely according to the child's symptoms.