Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (previously known as Benign Intracranial Hypertension or pseudotumour cerebri) is a cause of headaches classically seen in young, obese females of childbearing age who present with chronic daily headaches.  It is no longer called “benign” due to the risk of visual loss and blindness if left untreated.

Causes

The cause is unknown, though it is associated with:

• Oral contraception
• Anabolic steroids
• Vitamin A excess
• Obesity
• Tetracyclines

Presentation

The headache occurs daily. Typically, it is bi-frontal-temporal in location and made worse by straining. Transient visual loss may occur due to compression of the optic nerves and, in 10% of patients, visual impairment is permanent. Examination is often normal,though papilloedema may be detected (image, right) and there may be a visual field defect). A CN VI nerve palsy is the most common focal sign.

Papilloedema image courtesy of J Comm Eye Health.

Diagnosis

The diagnosis is made by reference to the modified Dandy criteria:

• Signs and symptoms of raised ICP. Cerebrospinal fluid (CSF) pressure >25cm H20
• No localising signs except a CN VI nerve palsy
• Normal CSF composition
• Normal to small (slit) ventricles on computerised tomography (CT) scanning with no intra-cranial mass

Learning Bite

Idiopathic Intracranial Hypertension is usually seen in younger women with chronic daily headaches. If suspected, a lumbar puncture (LP) and measurement of the opening pressure is essential.