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[Src: eMedicine]
= Idiopathic Intracranial Hypertension (= Benign Intracranial Hypertension = BIH = pseudotumor cerebri)
Diagnostic criteria [pubmed]:
  • sy of raised ICP
    • headache (up to 99%, diffuse, worse a.m., exacerbated by Valsalva)
    • transient visual obscurations (most patients, 1-5secs, 'greying out' of vision, induced by { standing up | bending over }
    • diplopia: usu due to uni/bilat 6th nerve (abducens) palsy: horizontal image displacement; (rarely vertical displacement: eg 3rd (oculomotor) or 4th nerve (trochlear) palsy)
    • nonspecific:
      • dizziness
      • N&V
      • tinnitus
    • rarely:
      • asymptomatic
  • sx of raised ICP
    • bilat papilloedema (rarely: asymmetric or unilat)
    • visual loss: enlarged blind spot (100%), progressive peripheral VF constriction / nerve fibre bundle defects, central VF affected only in end-stage chron papilloedema
    • sudden loss of central vision: if associated ant isch optic neuropathy, vascular occlusion, or subretinal neovascular membrane
    • 6th nerve (abducens) palsy
  • normal neuroimaging (except nonspecific findings of raised ICP)
  • icrd CSF pressure (>25cm H2O [pubmed: 95% nml=10-25]) with nml composition
Risk factors:
  • mostly: obese young women (although role of obesity unclear)
  • exogenous substances: drugs [NB: also withdrawal from corticosteroids]
  • systemic disease (eg with icrd blood viscosity), anaemia, chron respir insuff, familial Mediterranean fever, hypertension, MS, renal disease, sarcoidosis, SLE, ITP
  • disorders of cerebral venous drainage: eg cerebral venous compression by extravascular tumours or secondary thrombosis, post radical neck dissection (esp on right), cerebral sinus thrombosis
  • endocrine causes: pregnancy
Differential diagnosis
  • Pseudopapilloedema
  • Drusen of the optic nerve heads
  • malignant hypertension
  • bilat infiltrative/infectious/inflammatory optic neuropathy
  • bilat ant isch optic neuropathy
  • bilat optiv nerve papillitis
  • bilat optic nerve tumours (eg glioma, meningioma)
  • Imaging
    • urgent { CT | MRI+MR venography: r/o dural sinus thrombosis }: usu nml or small slitlike ventricles, enlarged optic nerve sheaths, occasionally empty sella
    • [ orbital US to measure optic nerve sheath diameter ]
  • Lumbar puncture: opening pressure (patient relaxed): NB can be transiently nml; [CSF: nml composition!]
  • monitor optic nerve fx
  • weight control if icrd BMI (as little as 6% can resolve papilloedema)
  • Tx underlying diseases
  • eliminate exogenous causative agents
  • Diuretics: Acetazolamide (Diamox): carboanhydrase inhibitor, lowers CSF production: { 500mg bd | 250mg qds } PO [-> 2g/d idd, although often limited by SE: paraestehesia, fatigue, metallic taste, dcrd libido]; alternatively: Furosemide (although less effective)
  • Corticosteroids: initially in addition to diuretics if severe papilloedema; if underlying inflammatory disease, but short-term use only
  • Surgical Tx if medical Tx ineffective (worsening visual fx):
    • optic nerve sheath fenestration: sometimes unilat, often bilat; long-term success only 16% ?
    • CSF diversion procedure: { lumboperitoneal | ventriculoperitoneal } shunt


if untreated: risk of irreversible optic neuropathy (VF constriction, loss of colour vision)