What is the appropriate workup for a patient presenting with unilateral pulsatile tinnitus?

Workup for Unilateral Pulsatile Tinnitus

Order high-resolution CT temporal bone (non-contrast) OR CT angiography (CTA) of head and neck with contrast as your first-line imaging study, based on clinical suspicion of the underlying cause, because unilateral pulsatile tinnitus has an identifiable structural or vascular cause in over 70% of cases and missing life-threatening conditions like dural arteriovenous fistula or arterial dissection can result in catastrophic hemorrhage or stroke. 1

Initial Clinical Assessment

Perform a focused otoscopic examination immediately to identify vascular retrotympanic masses (paragangliomas appear as red pulsatile masses behind the tympanic membrane), as this finding directly determines your imaging choice and can prevent delayed diagnosis. 1

Test for objective versus subjective tinnitus by listening with a stethoscope over the periauricular area, mastoid, orbit, and neck—objective tinnitus (audible to examiner) strongly suggests vascular pathology requiring immediate workup. 1

Perform the jugular/carotid compression test: gentle compression of the ipsilateral jugular vein or carotid artery that relieves the tinnitus suggests venous etiology (sigmoid sinus abnormalities, jugular bulb variants) or arterial dissection. 1

Order comprehensive audiologic examination (pure tone audiometry, speech audiometry, acoustic reflex testing) within 4 weeks for any unilateral tinnitus, as asymmetric hearing loss changes the imaging algorithm and raises concern for retrocochlear pathology like vestibular schwannoma. 1, 2

First-Line Imaging Strategy

Choose CT temporal bone (high-resolution, non-contrast) when you suspect:

• Paragangliomas or glomus tumors (especially if vascular retrotympanic mass on otoscopy) 1
• Jugular bulb abnormalities (high-riding jugular bulb or dehiscence of sigmoid plate) 1
• Superior semicircular canal dehiscence 1
• Aberrant venous anatomy (persistent petrosquamosal sinus, abnormal emissary veins) 1

Choose CTA of head and neck with contrast when you suspect:

• Dural arteriovenous fistulas (8% of cases, life-threatening—can cause hemorrhagic or ischemic stroke) 1
• Arterial dissection (potentially life-threatening, requires urgent identification) 1
• Atherosclerotic carotid artery disease (most common cause at 17.5% of cases) 1, 3
• Sigmoid sinus diverticulum or dehiscence (commonly associated with intracranial hypertension) 1
• Arteriovenous malformations 1

Use a mixed arterial-venous phase (20-25 seconds post-contrast) for CTA to capture both arterial and venous pathology in a single acquisition, maximizing diagnostic yield while minimizing radiation exposure. 1

Critical distinction: CTA source images can be reconstructed to create dedicated temporal bone CT images without additional radiation, making CTA a reasonable first choice when the differential is broad. 1

Second-Line Imaging

Reserve MRI brain with contrast and MR angiography (MRA) for:

• Suspected cerebellopontine angle lesions or acoustic neuroma (especially if asymmetric hearing loss is present) 1
• Vascular malformations not identified on CT/CTA 1
• Patients with contraindications to iodinated contrast 1
• When CT/CTA are negative but clinical suspicion remains high 1

High-Risk Populations and Red Flags

Young, overweight women with headaches and pulsatile tinnitus: Idiopathic intracranial hypertension (IIH) is the second most common cause of pulsatile tinnitus and can lead to permanent vision loss if missed—order CTA to evaluate for sigmoid sinus wall abnormalities and venous sinus stenosis. 1

Immediate escalation required if:

• Focal neurological deficits present (shift to stroke/hemorrhage protocol, not tinnitus protocol) 1, 2
• Vision changes accompany pulsatile tinnitus (suggests IIH) 1
• History of recent trauma or malignancy 2

Common Diagnostic Pitfalls

Missing dural AVF is the most dangerous error: This life-threatening cause can present with isolated pulsatile tinnitus before catastrophic hemorrhage, requiring high index of suspicion and appropriate vascular imaging (CTA or catheter angiography if CTA negative). 1

Dismissing pulsatile tinnitus as benign: Unlike bilateral non-pulsatile tinnitus, pulsatile tinnitus almost always requires imaging evaluation due to identifiable causes in >70% of cases. 1, 4

Inadequate otoscopic examination: Failing to identify vascular retrotympanic masses (paragangliomas) leads to inappropriate imaging selection and delayed diagnosis. 1

Ordering MRI/MRA first: While MRI is excellent for cerebellopontine angle lesions, CT temporal bone and CTA are superior for most causes of pulsatile tinnitus and should be ordered first unless acoustic neuroma is specifically suspected. 1

Differential Diagnosis by Category

Arterial causes (order CTA):

• Atherosclerotic carotid disease (17.5% of cases) 1, 3
• Arterial dissection 1
• Fibromuscular dysplasia 3

Arteriovenous causes (order CTA):

• Dural arteriovenous fistulas (8% of cases) 1
• Arteriovenous malformations 1

Venous causes (order CT temporal bone or CTA):

• Idiopathic intracranial hypertension (second most common cause) 1
• Sigmoid sinus diverticulum or dehiscence 1
• Jugular bulb abnormalities 1
• Aberrant venous anatomy (14% of cases) 3

Structural causes (order CT temporal bone):

• Paragangliomas/glomus tumors (16% of cases) 1, 3
• Superior semicircular canal dehiscence 1
• Adenomatous middle ear tumors 1

What NOT to Order

Do not order imaging for bilateral, symmetric, non-pulsatile tinnitus without localizing features—this represents inappropriate resource utilization with no benefit. 1 However, unilateral pulsatile tinnitus automatically meets criteria for imaging regardless of other features. 1, 5