13CT and Vascular Imaging for Pulsatile Tinnitus

FWhy pulsatile tinnitus earns its own imaging pathway

Most tinnitus is subjective, non-pulsatile, and never needs a scan. Pulsatile tinnitus is different: a rhythmic sound beating in time with the heart usually means real, turbulent or transmitted blood flow somewhere near the ear, and a meaningful minority of those patients harbour a structural lesion that is treatable — or, occasionally, dangerous if missed [2003].

The first fork is whether the noise is objective (the examiner can hear it with a stethoscope over the mastoid, neck or orbit) or subjective (only the patient hears it). The second fork is whether it is arterial (continuous, machinery-like, may have a bruit) or venous (a softer hum that quietens with ipsilateral neck compression or contralateral head turn). These bedside features steer which scan to order first and what the radiologist hunts for [2024].

THigh-resolution temporal-bone CT: the bone detectives

Thin-section (≤0.6 mm) temporal-bone CT is the workhorse for the objective, often conductive-flavoured pulsatile patient because it exquisitely shows bone. It detects superior semicircular canal dehiscence (a thin or absent bony roof producing a third-window pulse and autophony), a high-riding or dehiscent jugular bulb projecting into the middle ear, an aberrant internal carotid artery coursing through the tympanic cavity, a persistent stapedial artery, and the moth-eaten erosion of a glomus tympanicum or jugulare paraganglioma [2024].

CT also reveals the sigmoid sinus wall anomalies — dehiscence and diverticulum — that have emerged as a leading cause of venous pulsatile tinnitus, and the bony signs of idiopathic intracranial hypertension such as an empty sella and dilated optic nerve sheaths. Reading temporal-bone CT for pulsatile tinnitus is therefore a structured checklist, not a glance.

TCTA/CTV and MRA/MRV: imaging the flow

When the question shifts from bone to lumen, cross-sectional angiography takes over. CT angiography and venography (CTA/CTV) give superb arterial and venous luminal detail with bone in the same dataset, ideal for confirming an aberrant carotid, sigmoid sinus diverticulum, or transverse-sinus stenosis. Contrast-enhanced MR angiography and venography (MRA/MRV), paired with routine brain and internal-auditory-canal MRI, avoid ionising radiation and add soft-tissue and flow-related information — useful when a dural arteriovenous fistula or venous stenosis from intracranial hypertension is suspected [2008].

A dural arteriovenous fistula is the lesion no one wants to miss: it can present with isolated pulsatile tinnitus yet carry a risk of haemorrhage, so suggestive arterial-side findings — engorged transosseous feeders, early venous filling, asymmetric flow voids — mandate escalation rather than reassurance.

CCatheter DSA: the reference standard

Digital subtraction angiography (DSA) remains the gold standard for vascular pulsatile tinnitus because its dynamic, selective injections show the timing and direction of flow that static CT/MR snapshots cannot. It is the only reliable way to fully characterise a dural arteriovenous fistula (Cognard/Borden grading), to confirm or exclude a small fistula when non-invasive imaging is equivocal, and to plan or deliver endovascular treatment in the same sitting [2024].

Because DSA is invasive and carries a small stroke risk, it is reserved for cases where the bedside picture and non-invasive imaging point to an arterial/fistulous cause, or where strongly suspected pathology has not been explained. In idiopathic intracranial hypertension with transverse-sinus stenosis, DSA with manometry both confirms the pressure gradient and serves as the platform for venous stenting, which can abolish the tinnitus — although the noise may persist or recur in some patients [2025][2025].

CPutting it together: an arterial-versus-venous algorithm

A practical pathway begins with otoscopy and auscultation. A retrotympanic mass or objective bruit, conductive picture, or third-window symptoms favour temporal-bone CT first. A soft venous hum that compresses away in a patient with headache and visual symptoms favours MR/MRV with attention to the sinuses and signs of raised pressure. A continuous arterial bruit, especially with any neurological feature, pushes toward CTA/MRA and a low threshold for DSA to exclude a fistula [2008].

Even a thorough work-up leaves a proportion of pulsatile tinnitus unexplained, and a focused, character-driven approach maximises yield while sparing low-risk patients unnecessary radiation and contrast [2025].