Idiopathic Intracranial Hypertension

Aka pseudotumour cerebri

Diagnosis of exclusion: after MRI/MRV and CSF analysis and with elevated LP opening pressure

F>M

• 3.3/100,000 women
• 22/100,000 obese young women
• In children: less likely to be overweight and M=F
• Obesity is the primary risk factor (or recent weight gain)
• Annual incidence of blindness in UK was 1-2%
• Drug causes of intracranial hypertension (not technically IIH):
  • Tetracyclines
  • Cyclosporine
  • Isotretinoin (vitamin A derivatives)
  • Oral contraceptives
  • Prednisolone
  • Synthetic growth hormone

Clinical features

Essentially the same as for papilloedema more generally

• 94% have headache: majority have migrainous features, daily, diffuse headache
• Retrobulbar pain
• Sixth nerve palsy
• CSF rhinorrhoea
• IIH may recur at any time after initial episode has resolved
• IIH without papilloedema (IIHWOP): rare subtype

Tests: as above for papilloedema

• MRI with gadolinium enhancement with venography

  • Flattening of the pituitary gland: ‘empty sella’ sign

• LP should only be done after neuroimaging: normal CSF composition but raised opening pressure

• VF

• OCT can monitor papilloedema and macular features

Management

• Weight loss: this is the only disease-modifying strategy

• Acetazolamide: there is evidence to support its use in patients with mild visual loss to reduce CSF secretion (up 4g daily)

• Furosemide

• Topiramate

• Digoxin

• Ventriculoperitoneal, lumboperitoneal or ventriculoatrial shunting, indications:

  • Sight-threatening disease/progressive visual loss
  • Intractable headaches despite maximal medical therapy

• Optic nerve sheath fenestration: sight-threatening disease

  • Fenestrations scar quickly: 15% success rate at 6 years

• Steroids are sometimes used in severe papilloedema (controversial)

• IV mannitol

• Referral to headache clinics

• Regular monitoring of visual function

• Counselling re pregnancy: can worsen disease/active IIH can complicate delivery