Idiopathic intracranial hypertension

Background

aka. pseudotumor cerebri

Increase in intracranial pressure without an identifiable cause
Defined as elevated opening pressure > 25cm H2O on lumbar puncture without identifiable intracranial structural pathology

History
- Diffuse, steady or throbbing headache that is worse in the morning
- Visual obscurations: bilateral dimming of vision lasting seconds
- Blurred vision, scotomas, and diplopia
- Pulsatile tinnitus, dizziness, and neck pain
Signs & Symptoms
- Papilledema
- Strabismus from CN VI palsy

Primary or idiopathic: includes obesity, recent weight gain, polycystic ovarian syndrome, and thin children
Secondary
- Cerebral venous abnormalities
  - Cerebral venous sinus thrombosis
  - Bilateral jugular vein thrombosis or surgical ligation
  - Otitis media or mastoid infection
  - Right heart failure
  - Superior vena cava syndrome
  - Arteriovenous fistula
  - Decreased CSF absorption from prior infection or subarachnoid hemorrhage
- Medications and other exposures
  - Antibiotics: tetracycline, minocycline, doxycycline, nalidixic acid, sulfa drugs
  - Vitamin A and retinoids: hypervitaminosis A, isotretinoin, all-trans retinoic acid, excessive liver ingestion
  - Hormones: human growth hormone, thyroxine (in children), leuprorelin acetate, levonorgestrel, anabolic steroids
  - Withdrawal from chronic corticosteroids
  - Lithium
  - Chlordecone
- Medical conditions
  - Endocrine disorders: Addison disease, hypoparathyroidism, hypothyroidism
  - Hypercapnia: sleep apnea, Pickwickian syndrome, COPD
  - Infections: otitis media, Lyme disease, HIV, sinusitis, VZV, pharyngitis from group B streptococci, other febrile illnesses
  - Anemia
  - Renal failure
  - Systemic lupus erythematosus
  - Sarcoidosis
  - Turner syndrome
  - Down syndrome

Imaging
- MRI brain may show small ventricles, partially empty sella turcica, widening of the optic nerve sleeves, optic nerve buckling, or flattening of the optic globes, or may be normal
Other
- Lumbar puncture with opening pressure for diagnosis
- Visual field testing is crucial

Papilledema, with all of the following:
- Normal neurologic examination except for cranial nerve abnormalities
- Neuroimaging showing
  - Typical patients (female and obese): normal brain parenchyma without evidence of hydrocephalus, mass, or structural lesion, and no abnormal meningeal enhancement on MRI (with and without gadolinium)
  - Others: MRI (with and without gadolinium) plus MRV
  - If MRI unavailable, then CT with contrast
- Normal CSF
- Elevated lumbar puncture opening pressure ≥250 mm in adults or ≥280 mm in children
No papilledema:
- All of the above criteria are met, plus there is unilateral or bilateral abducens nerve palsy
No papilledema, and no abducens nervy palsy:
- Cannot be diagnosed, but can be suggested if all of the above criteria are met, plus at least 3 of the following are seen on neuroimaging:
  - Empty sella
  - Flattening of the posterior aspect of the globe
  - Distention of the perioptic subarachnoid space with or without a tortuous optic nerve
  - Transverse venous sinus stenosis

Discontinue offending medication, if any
LP for decompression, including repeated
May need surgical intervention if sight is threatened or treatment with medication fails

Medication
- Acetazolamide 250-500 mg p.o. twice daily, and titrated up to a maximum of 4 g total daily dose
- Topiramate
- Corticosteroids
Repeat LPs, often every 1-3 months despite medications
Remove causative factors, including counselling on weight loss
Refer to Ophthalmology and Neurology

^ D. I. Friedman, G. T. Liu, K. B. Digre. Revised diagnostic criteria for the pseudotumor cerebri syndrome in adults and children. Neurology. 2013;81(13):1159-1165. doi:10.1212/wnl.0b013e3182a55f17.