Idiopathic Intracranial Hypertension

Background

• Idiopathic intracranial hypertension is a rare disorder characterized by elevated intracranial pressure with no established cause.
• Clinical presentation varies.
  • The most common symptoms are headaches, transient visual darkening, and pulsating tinnitus.
  • Papilledema is common.
  • Some patients have impaired vision, and there is the potential for permanent vision loss.
• Risk factors include obesity and female sex.

Evaluation

• Determine headache characteristics to help guide management.
• Assess visual acuity and for papilledema. Also conduct formal visual field tests.
• Perform basic neurological assessment including cranial nerve exam.
• Eliminate possible secondary causes of intracranial hypertension:
  • Ask about medications that may raise intracranial pressure.
  • Take blood pressure (BP) to exclude malignant hypertension (diastolic BP ≥ 120 mm Hg or systolic BP ≥ 180 mm Hg).
  • Conduct brain magnetic resonance imaging (MRI) (or computed tomography [CT] if MRI not available) and MR or CT venography within 24 hours of clinical examination.
  • Order full blood count to exclude anemia and consider other blood tests based on clinical suspicion.
  • Perform lumbar puncture to assess cerebrospinal fluid (CSF) opening pressure and contents.
  • Evaluate for diseases/conditions that may explain signs and symptoms including hematological conditions, brain tumors, other causes of headache, conditions that may impair venous drainage, endocrine disorders, systemic disorders, chromosomal conditions, and syndromic conditions.
• Diagnostic criteria for idiopathic intracranial hypertension with papilledema includes all of the following:
  • papilledema
  • normal neurological findings except for possible sixth cranial nerve palsy
  • negative neuroimaging findings for meningeal enhancement, hydrocephalus, and mass, structural, and vascular lesions
  • no cerebral sinus thrombosis on CT/MR venography
  • CSF opening pressure ≥ 25 cm by lumbar puncture in adults (for children, it is unclear what should be considered "elevated")
  • normal CSF constituents
• Idiopathic intracranial hypertension without papilledema requires sixth cranial nerve palsy for diagnosis.

Management

• For any patient with obesity (body mass index ≥ 30 kg/m²), advise weight management such as diet, medications, and bariatric surgery (if indicated).
• For patients with symptoms but without imminent threat to vision, consider medical therapy:
  • Acetazolamide starting dose 250-500 mg orally twice daily; titrate as tolerated to maximum 4,000 mg/day.
  • If acetazolamide is not tolerated or not appropriate, consider topiramate orally 100-150 mg/day, but use caution in women due to potential teratogenetic risks and interference with hormonal regimens.
• For patients with imminent threat to vision (evidence of declining visual function within 4 weeks of idiopathic intracranial hypertension diagnosis) consider:
  • optic nerve sheath fenestration (ONSF).
  • CSF diversion shunting.
  • neurovascular stenting.
• Consider headache-directed management for all patients with headache:
  • Discuss and assess for medication overuse headache (MOH).
  • Initial acute management strategies include short-term simple analgesics such as acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs).
  • For migraine-like headaches, consider migraine prophylaxis and acute treatment (limited to ≤ 2 days/week and ≤ 10 times/month) with simple analgesics or triptans.
  • For patients with cerebrospinal fluid diversion shunts:
    • If inadequate response to initial headache management, refer to headache specialist and consider monitoring intracranial pressure.
    • If clinical suspicion of central nervous system infection, perform lumbar puncture or shunt tap to gather cerebrospinal fluid for microbiological evaluation assessment and culture.
    • If no central nervous system infection, assess papilledema with fundoscopy and assess visual function.
• Follow-up should include:
  • regular assessments of headache symptoms and body mass index.
  • increased outpatient observation for pregnant women.
  • documented eye and vision assessments for patients with papilledema.