Cerebral venous sinus thrombosis

Cerebral venous sinus thrombosis is a blood clot in the large venous channels, or sinuses, that drain blood from the brain. It is an uncommon kind of stroke that commonly presents with headache and rarely with a pulsing sound in one ear. It needs emergency assessment, and the recommended treatment is anticoagulation.

Why it matters for tinnitus

It connects to pulsatile tinnitus in three ways. A clot in the sigmoid sinus can present as the sound, sometimes with no other symptom. A clot can raise the pressure around the brain and imitate idiopathic intracranial hypertension. And a clot can leave behind an acquired dural arteriovenous fistula, an abnormal artery-to-vein shunt that can cause pulsatile tinnitus of its own.

In children it is a rare but serious complication of acute mastoiditis. Surgery for pulsatile tinnitus carries a small risk of it: in a systematic review of 141 resurfacing operations, 4% had major complications involving sigmoid sinus thrombosis or compression, none with lasting harm.

What the evidence says

The tinnitus-specific evidence is thin: case reports and small series.

• Case series. Four women with sigmoid sinus thrombosis all had a localised headache, and two had one-sided pulsatile tinnitus. Imaging had to be repeated or changed to find the clot.
• Case report and review. A 2012 review found ten published cases of pulsatile tinnitus with this clot. In most, the tinnitus was the only symptom, and nearly all recovered fully with anticoagulation.
• Retrospective review. At three neuro-ophthalmology centres, 10 of 106 people (9.4%) presumed to have idiopathic intracranial hypertension had this clot instead. MRI alone showed 1 of the 10; MR venography showed all 10.
• Cohort and case series. An exploratory cohort rescanned 24 people after six months and found a new fistula in 2 (8.3%); one needed treatment for debilitating headache and tinnitus. In a retrospective series of 15 people whose fistula followed a clot, 5 had pulsatile tinnitus.
• Scientific statement. The American Heart Association's 2024 statement puts the condition at 0.5% to 3% of strokes, with death or dependence in 10% to 15% despite treatment. It names young people, women of reproductive age and people prone to clotting as the most vulnerable.
• Case-control study and meta-analyses. Among 163 women with the condition and 1,230 controls, risk rose after delivery (adjusted odds ratio 10.6), highest in the first six weeks (18.7), but not in pregnancy (1.2). A 2025 meta-analysis put postpartum cases at 7 per 100,000 deliveries. A 2015 meta-analysis of 11 studies found the odds 7.59 times higher in women aged 15 to 50 taking the contraceptive pill.
• Guideline. The 2017 European Stroke Organization guideline recommends parenteral anticoagulation, preferably low-molecular-weight heparin, in the acute phase. For women who have had this clot, it suggests avoiding oestrogen-containing contraceptives, and that later pregnancies are safe, with preventive heparin considered through pregnancy and the puerperium.

What this means for you

• Call your local emergency number or go to an emergency department if a pulsing sound comes with a sudden or new severe headache, sudden neck pain, a drooping eyelid or a change in vision, or if you have sudden weakness or drooping in the face or an arm, or trouble speaking or seeing.
• Pulsatile tinnitus without those signs still needs an assessment within a few weeks, sooner if headaches or vision changes are building.
• Tell whoever assesses you if you gave birth in the last three months, take a contraceptive pill, or have had a clot before.
• If you are scanned, ask whether the veins were imaged: a standard MRI can miss this clot.
• After a sinus thrombosis, report any new or changed whooshing, since a fistula can form later.

How it connects

• Pulsatile tinnitus: causes, workup and urgency.
• Intracranial hypertension: the condition a clot can imitate.
• Dural arteriovenous fistula: the shunt a clot can leave behind.
• Mastoiditis: an ear infection that can cause sinus thrombosis in children.
• Stroke and tinnitus: arterial stroke and its emergency signs.
• Cervical artery dissection: another emergency cause of a pulsing sound.
• Sigmoid sinus wall abnormalities: the finding resurfacing surgery repairs.
• Intracranial aneurysm and pulsatile tinnitus: an arterial cause of the same sound.