11IIH and Venous Sinus Interventions

FRaised pressure, turbulent flow, a bruit

Idiopathic intracranial hypertension (IIH) is a syndrome of elevated cerebrospinal-fluid pressure without a mass lesion, occurring overwhelmingly in women of reproductive age with raised body-mass index. Headache and visual obscurations dominate the classic picture, but for a distinct subgroup the presenting and most troublesome symptom is pulsatile tinnitus [2025].

The sound is venous in origin. Raised intracranial pressure transmits to the dural venous sinuses and frequently produces a stenosis of the transverse–sigmoid sinus. Blood accelerating through that narrowing becomes turbulent, and because the sinus lies millimetres from the cochlea, the patient hears a continuous heartbeat-locked rushing — a bruit. Recognising this venous, flow-related mechanism is what makes the tinnitus treatable rather than merely maskable [2013].

TThe stenosis self-reinforcing loop

Transverse-sinus stenosis in IIH is partly cause and partly consequence, creating a vicious circle. Two patterns occur: an intrinsic stenosis from an arachnoid granulation or septum, and an extrinsic stenosis where high CSF pressure compresses a soft sinus segment. Either way, the stenosis raises venous pressure upstream, which impairs CSF absorption at the arachnoid granulations, which raises intracranial pressure further, which worsens the compression.

This loop explains why simply lowering pressure can open an extrinsic stenosis, and why opening a fixed intrinsic stenosis with a stent can drop the pressure. It also explains the bruit’s behaviour at the bedside: pulsatile tinnitus from venous stenosis characteristically quietens or stops when the ipsilateral internal jugular vein is gently compressed in the neck or when the head is turned, because these manoeuvres alter venous outflow and the turbulent gradient.

CDiagnosis and medical therapy first

Diagnosis follows the revised Friedman criteria: papilloedema, a normal neurological examination apart from cranial-nerve VI, normal neuroimaging that nonetheless excludes secondary causes, normal CSF composition, and an elevated opening pressure on lumbar puncture (>25 cm CSF in adults) [2013]. MR venography demonstrates the transverse-sinus stenosis and fundoscopy or OCT documents the papilloedema that protects vision must not be missed.

First-line treatment is medical and targets the pressure, not the ear. Weight loss is disease-modifying and can be curative in mild disease. Acetazolamide, a carbonic-anhydrase inhibitor that reduces CSF production, improved visual-field outcomes in the randomised IIH Treatment Trial and is the pharmacological mainstay [2014]. As the pressure falls, an extrinsic stenosis may reopen and the bruit fade — so genuine procedural intervention is reserved for those who fail medical therapy or have threatened vision.

CVenous sinus stenting for the bruit

When a fixed transverse-sinus stenosis drives disabling pulsatile tinnitus despite medical therapy, endovascular venous sinus stenting is the targeted treatment. Under angiographic guidance a self-expanding stent is deployed across the stenosis, abolishing the trans-stenotic pressure gradient. With the narrowing relieved, flow becomes laminar, the turbulence disappears, and the bruit characteristically resolves — often on the operating table.

Series of IIH patients stented primarily for tinnitus report resolution of pulsatile tinnitus in the great majority, with parallel improvement in headache and papilloedema [2016]. Candidacy hinges on demonstrating a meaningful pressure gradient across the stenosis on catheter venography — stenting an incidental, non-gradient narrowing will not help. Patients require dual antiplatelet therapy around the procedure.

CCSF diversion and choosing the route

For patients whose problem is global raised pressure and threatened vision rather than an isolated stenosis, CSF diversion — a ventriculoperitoneal or lumboperitoneal shunt — lowers pressure throughout the system and can likewise quiet the bruit. Optic-nerve-sheath fenestration protects vision but does not reliably treat tinnitus because it does not address venous turbulence.

The modern algorithm is therefore mechanism-led: weight loss and acetazolamide for everyone; venous stenting when a gradient-positive stenosis is the dominant driver and tinnitus is the leading complaint; shunting when generalised pressure or vision is the priority. Pulsatile tinnitus from IIH is one of the genuinely curable tinnitus syndromes, but only when the underlying pressure and venous anatomy are correctly characterised first.