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Pulsatile tinnitus

Patients presenting with pulsatile tinnitus—subjective or objective perception of rhythmic noise synchronous with heartbeat—require imaging evaluation to determine underlying vascular or non-vascular etiology.

Key Images

Causes

Look For First
  • Vascular abnormality in temporal bone or neck causing hemodynamic turbulence (stenosis, anomalous vessel, lateralized/aberrant ICA)
  • Sigmoid sinus diverticulum, laterally placed sigmoid sinus, or jugular bulb diverticulum with or without plate dehiscence
  • Dural arteriovenous fistula or paraganglioma (hypervascular mass in middle ear/jugulotympanic region)
  • Idiopathic intracranial hypertension with transverse sinus stenosis on MRV
Key Image Findings
  • CTA and MRA are complementary modalities: CTA excels at detecting fine arterial anatomy and atherosclerotic stenosis; MRA evaluates both arterial and venous systems without ionizing radiation.
  • CT venography and MR venography essential for evaluating dural venous sinus anatomy: look for transverse sinus stenosis, sigmoid sinus lateral placement, diverticula, or high-riding/dilated jugular bulb.
  • High-resolution CT of temporal bone without contrast shows fine osseous detail: semicircular canal dehiscence, jugular plate dehiscence, sigmoid plate dehiscence, and abnormal mastoid emissary veins.
  • Arterial findings include atherosclerotic narrowing (especially ICA in elderly), arterial dissection, fibromuscular dysplasia, and variant anatomy such as aberrant ICA or persistent stapedial artery.
  • Paraganglioma appears as intensely enhancing mass in jugulotympanic region on contrast-enhanced MRI or CTA, often with 'salt-and-pepper' appearance on T2-weighted imaging due to flow voids.
  • Dural arteriovenous fistula shows prominent arterialized veins, cortical venous reflux, and early venous enhancement relative to normal venous phase on dynamic contrast-enhanced studies.
  • Idiopathic intracranial hypertension manifests as transverse sinus stenosis (often bilateral and asymmetric) on MRV, with flattened pituitary gland and empty sella on brain MRI.
  • Semi-invasive digital subtraction angiography reserved for cases where non-invasive imaging inconclusive or when therapeutic intervention (fistula embolization) anticipated.
Differential Diagnosis
  • Sigmoid sinus diverticulum (most common vascular cause) vs. normal anatomic variant: diverticulum shows outpouching of lateral sigmoid sinus wall, often with audible bruit on auscultation suppressed by ipsilateral IJV compression.
  • Dural arteriovenous fistula vs. arteriovenous malformation: DAVFs supplied by dural branches with early cortical venous reflux; AVMs typically have nidus within brain parenchyma.
  • Paraganglioma vs. hemangioma: paraganglioma is intensely enhancing with flow voids and typically jugulotympanic location; hemangioma may be more homogeneous and less aggressive-appearing.
  • Idiopathic intracranial hypertension with transverse sinus stenosis vs. primary venous stenosis: IIH shows clinical correlation with papilledema and obesity; elevated CSF opening pressure on LP.
  • Aberrant or lateralized internal carotid artery vs. atherosclerotic stenosis: aberrant ICA shows atypical course in middle ear/temporal bone on CT; stenosis shows plaque-induced luminal narrowing.
  • Palatal myoclonus or middle ear myoclonus (non-vascular) vs. vascular pulsatile tinnitus: myoclonic causes show rhythmic muscle contraction unrelated to vessel hemodynamics; clinical history of synchronization with heartbeat favors vascular.
Discussion

Pulsatile tinnitus is heterogeneous: most common vascular causes are atherosclerotic arterial stenosis (elderly), sigmoid sinus diverticulum, and idiopathic intracranial hypertension; paraganglioma most common hypervascular tumor cause.

Clinical features guide imaging interpretation: objective tinnitus with low-pitched hum and IJV compression response suggests venous etiology; retrotympanic mass on otoscopy suggests neoplasm or vascular anomaly.

Multimodality imaging approach essential because diverse etiologies require different technical strengths: CTA for arterial detail and stenosis, MRV/CT venography for sinus anatomy, high-resolution temporal bone CT for osseous dehiscence.

American College of Radiology guidelines recommend CTA head/neck, CT venography, CT temporal bone, and MRI/MRA as usually appropriate; DSA reserved for therapeutic intervention or inconclusive non-invasive studies.

Subjective pulsatile tinnitus (heard only by patient) more common than objective (audible on auscultation); both warrant vascular imaging because hemodynamically significant lesions may not produce audible bruit.

Non-vascular causes (palatal myoclonus, Eustachian tube dysfunction, temporal bone pathology) may mimic vascular pulsatile tinnitus clinically; imaging helps exclude vascular etiology and direct clinical management accordingly.

Reporting Pearls

In describing pulsatile tinnitus findings, clearly specify the anatomic location and nature of the abnormality (e.g., "laterally placed sigmoid sinus with sigmoid plate dehiscence," "transverse sinus stenosis bilateral and asymmetric compatible with idiopathic intracranial hypertension," or "intensely enhancing jugulotympanic mass consistent with paraganglioma"), and note whether findings can be suppressed by ipsilateral IJV compression or are sonographically/audibly confirmed as objective, as these clinical correlations strengthen the causative diagnosis.

Pitfalls
  • Mistaking normal anatomic variants (e.g., high-riding jugular bulb, lateral sigmoid sinus) for pathology: correlation with symptom laterality and clinical auscultation findings (suppression with IJV compression) essential to confirm causation.
  • Over-interpreting transverse sinus narrowing as stenosis in young, healthy patients: mild asymmetric narrowing is common normal variant; must correlate with papilledema, obesity, and elevated CSF opening pressure to diagnose IIH.
  • Relying solely on arterial imaging without venous imaging in cases with high clinical suspicion for venous etiology: dural venous sinus abnormalities may be subtle on CTA; dedicated MRV or CT venography required.
  • Failing to evaluate the contralateral side: some vascular lesions (e.g., transverse sinus stenosis in IIH, paragangliomas) can be bilateral; unilateral imaging may miss secondary etiologies or alternative causes of persisting symptoms.
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