Idiopathic intracranial hypertension

aka. pseudotumor cerebri

Definition

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

Pathophysiology

• Most likely from elevated venous pressure causing decreased CSF resorption

Differential Diagnosis

• Severe iron deficiency anemia
• Sickle cell anemia
• Leukemia
• Addison disease
• Pregnancy, PCOS
• Hypothyroidism, thyrotoxicosis
• Hypocalcemia
• Renal failure
• COPD
• Right heart failure with lumpnary hypertension
• OSA
• SLE, sarcoid
• CSVT/IJV thrombus
• Meningitis
• Otitits media, lyme, HIV, varicella, sinusitis, viral disease, febrile illness, Strep B pharyngitis
• Medication

Risk Factors

• Obese female of child-bearing age
• Hypervitaminosis A
• Tetracycline antibiotics
• Isotretinoin
• Oral contraceptive pills
• Phenytoin
• Pregnancy
• Glucocorticoid use or withdrawal

Clinical Manifestations

• 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

Investigations

• Labs
• 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

Criteria

• modified dandy's criteria
• s/s of increased ICP
• no neuro signs except CN VI palsy
• normal CSF
• no hydrocephalus/mass/etc on MRI
• no other cause of incranranial hypertension
• opening pressure >25cm
• clear clinical response to LP drainage

Management

• Acute
  • Discontinue offending medication, if any
• Chronic
  • Acetazolamide
  • Topiramate
• LP for decompression, including repeated
• Medication
  • Acetazolamide
  • Topiramate
  • Corticosteroids
• Repeat LPs, often every 1-3 months despite medications
• Remove causative factors, including counselling on weight loss
• Refer to Ophthalmology and Neurology
• May need surgical intervention if sight is threatened or treatment with medication fails