Idiopathic Intracranial Hypertension

What is IIH?

Idiopathic intracranial hypertension (IIH), also known as pseudotumour cerebri, is a condition in which the pressure of cerebrospinal fluid (CSF) surrounding the brain is abnormally elevated with no identifiable underlying cause such as a tumour or blockage. It predominantly affects women of childbearing age who are overweight, though it can affect anyone.

Symptoms

The hallmark symptom is a severe, persistent daily headache. Other common symptoms include:

Transient visual obscurations — brief greying or blacking of vision lasting seconds
Blurred or double vision
Pulsatile tinnitus — a whooshing sound in the ears
Pain behind the eyes
Visual field loss — a serious complication that can be permanent if untreated

IIH can cause permanent vision loss if untreated. Early diagnosis and management are essential.

Diagnosis

Diagnosis requires: signs of raised intracranial pressure, normal brain MRI/CT, elevated CSF opening pressure on lumbar puncture (>25 cmH2O in adults), and normal CSF composition. MRI may show empty sella, flattened posterior globes, and tortuous optic nerve sheaths. Visual field testing and ophthalmological review are essential.

Venous sinus stenosis and IIH

An increasingly recognised association exists between IIH and narrowing of the cerebral venous sinuses — most often the transverse sinuses. In selected patients, this narrowing impairs CSF absorption by raising venous pressure. Venous sinus stenting can significantly improve symptoms in appropriately selected patients with a documented pressure gradient across the stenosis.

Treatment options

Weight loss — most effective long-term treatment; even 5-10% reduction significantly lowers ICP
Acetazolamide (Diamox) — reduces CSF production; first-line medication
Repeated lumbar puncture — temporary relief; useful in acute visual threat
CSF shunting — ventriculoperitoneal or lumboperitoneal shunt for refractory cases
Optic nerve sheath fenestration — for rapidly deteriorating vision
Venous sinus stenting — endovascular treatment for selected patients with significant transverse sinus stenosis and elevated venous pressure gradient

Venous sinus stenting

In patients with IIH associated with a haemodynamically significant transverse sinus stenosis (pressure gradient >4 mmHg on venous manometry), a self-expanding venous stent placed across the stenosis can reduce venous pressure, improve CSF absorption, and lower intracranial pressure. The procedure is performed under local anaesthesia via a femoral or radial venous approach. Pressure measurements before and after stenting confirm haemodynamic improvement. Published data shows sustained reduction in ICP and improvement in headache and vision in appropriately selected patients.

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