7Sigmoid Sinus and Jugular Bulb Procedures

FWhy a thin bone makes a loud noise

Most blood flow through the head is silent because it is laminar and walled off from the air-filled middle ear and mastoid by dense bone. When the bony plate over the sigmoid sinus thins to nothing — a dehiscence — or when the sinus wall balloons outward into the mastoid air cells as a diverticulum, the normally inaudible pulsations of venous flow are transmitted directly into the temporal bone and cochlea. The result is a low-pitched, whooshing sound that is exactly synchronous with the heartbeat [2013].

These sigmoid sinus wall abnormalities are now recognised as one of the commonest identifiable causes of venous pulsatile tinnitus, particularly on the right side, where venous drainage is usually dominant. The key teaching point for trainees is that this is a mechanical — not a neural — problem: the sound is real, generated by turbulent flow, and it can often be abolished by restoring the missing bony barrier [2008].

TMaking the diagnosis before reaching for the drill

The diagnosis rests on a careful history (unilateral, pulse-synchronous, often abolished by light pressure over the ipsilateral neck or by turning the head), examination for an objective bruit, and dedicated cross-sectional imaging. A modified CT angiogram/venogram and high-resolution temporal bone CT demonstrate the dehiscence or diverticulum and, crucially, exclude arterial mimics such as a dural fistula, an aberrant carotid artery, or a glomus tumour [2008].

An essential and frequently missed association is idiopathic intracranial hypertension (IIH). Sigmoid sinus wall anomalies cluster strongly with transverse sinus stenosis and raised intracranial pressure, so the work-up should include fundoscopy for papilloedema and consideration of lumbar-puncture opening pressure before any operation [2020]. Operating on the sinus while ignoring uncontrolled IIH risks failure and recurrence.

CThe operation: resurfacing and reconstruction

The aim of surgery is to dampen the transmission of pulsation, not to obliterate the vein. Through a transmastoid, postauricular approach the surgeon performs a cortical mastoidectomy and skeletonises the sigmoid sinus until the dehiscence or diverticulum is exposed. The defect is then resurfaced: the diverticulum is gently reduced and the wall is rebuilt with a rigid layer — cortical bone pate, cartilage, titanium mesh or a soft-tissue and bone-cement composite — to re-establish the acoustic barrier while preserving the lumen and venous outflow [2018].

Preserving patency is the cardinal safety principle: over-aggressive compression or packing can produce sinus thrombosis or, in a patient with unrecognised IIH, dangerous intracranial venous hypertension. Postoperative imaging confirms that the reconstruction is in place and the sinus remains patent [2016].

COutcomes — the most curable pulsatile tinnitus

In appropriately selected patients the results are among the most gratifying in otology. Long-term series of sigmoid sinus wall reconstruction report complete or near-complete resolution of pulsatile tinnitus in the large majority of patients, with durable benefit on extended follow-up and a low rate of significant complication [2024].

Failures cluster in two groups: patients whose tinnitus arose partly from another cause that was not addressed, and patients with untreated raised intracranial pressure driving ongoing transverse sinus stenosis. Recurrence after a technically complete repair is uncommon, which underlines why correct selection — the right anatomy, the right pressure, the right ear — matters more than surgical virtuosity [2018].