Intracranial aneurysm and pulsatile tinnitus

An intracranial aneurysm, a bulge in a weakened artery wall inside the skull, is a rare cause of pulsatile tinnitus, the whooshing that keeps time with the heartbeat. Most reported cases involve the internal carotid artery where it runs through the skull base close to the ear, and most aneurysms cause no symptoms.

Why it matters for tinnitus

A thorough evaluation finds a cause for pulsatile tinnitus in more than 70% of people, and a UK radiology review notes that venous causes are more common than arterial ones such as aneurysms. Pulsatile tinnitus is still imaged, to find causes that are treatable or dangerous.

A few aneurysms produce the sound, mostly on the petrous segment of the internal carotid artery; one inside the cavernous sinus, a venous channel, can do so by rupturing into it. And a scan done for the pulsing can find an aneurysm unrelated to it.

What the evidence says

The evidence is thin: case reports, small series, and imaging series in which an aneurysm is one finding among many.

• Imaging case series. In a Swiss series of 84 people, a vascular cause was found in 36 (42%), most often a dural arteriovenous or carotid-cavernous fistula; carotid aneurysm was among the rest. Of 57 Korean patients with vascular pulsatile tinnitus, 3 had an intracranial aneurysm and 27 a high jugular bulb.
• Retrospective cohort. A UK review of 272 people scanned for pulsatile tinnitus found intracranial aneurysms and arteriovenous malformations at rates comparable to the general population; in 8 of 18 people with findings needing action, the finding did not match the side of the sound. The authors suggest such findings could be incidental.
• Meta-analysis. Pooling 68 studies (94,912 people) put unruptured intracranial aneurysms at 3.2% of adults without a related condition.
• Review and case series: petrous aneurysms. These are rare and can be found by chance. Reported presentations include pulsatile tinnitus, cranial nerve palsies, nosebleeds and bleeding from the ear; in one series of three, one person presented with pulsatile tinnitus.
• Cohort and case reports: cavernous aneurysms. Of 276 followed in Helsinki, 73% stayed symptom-free, and none of the 10 that ruptured caused a subarachnoid haemorrhage or a death. In a Toronto series, 10 of 12 spontaneous direct carotid-cavernous fistulas came from a ruptured cavernous aneurysm; one case report describes such a fistula causing pulsatile tinnitus.
• Case reports: other sites. A 1993 report of an anterior communicating artery aneurysm presenting as pulsatile tinnitus found only 8 published cases of an aneurysm presenting this way. A 2012 report describes a paraclinoid carotid aneurysm whose only symptom was the sound; it was treated with coils.
• Treatment. In the Korean series, all 3 aneurysms were embolised and the tinnitus stopped immediately.
• A naming trap. A sigmoid sinus "aneurysm" is a venous bulge; see sigmoid sinus wall abnormalities.

What this means for you

• Call your local emergency number or go to an emergency department if a pulsing sound comes with a sudden 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, trouble speaking or seeing, or severe vertigo or loss of balance that will not settle. The NHS names a sudden, severe headache as the main symptom of a burst aneurysm.
• Without those signs, pulsatile tinnitus still needs an assessment within a few weeks, sooner if headaches or vision changes are building. European radiology recommendations say it always needs imaging, usually CT or MRI of the vessels (do you need a scan?).
• If a scan shows an aneurysm, ask whether its side and site could explain the sound. The NHS says small aneurysms causing no symptoms are not usually treated, as they often do not grow and rarely burst.

How it connects

• Pulsatile tinnitus: causes, workup and urgency.
• Is tinnitus a sign of something serious?: feared causes, in proportion.
• Dural arteriovenous fistula: 5 cases against 3 aneurysms in the Korean series.
• Cervical artery dissection: a pulsing sound with neck pain.
• Cerebral venous sinus thrombosis: a venous cause with emergency signs.