What is the differential diagnosis for a patient presenting with pulsatile tinnitus, characterized by a whooshing sound in the ear, considering potential underlying vascular and other serious conditions?

Differential Diagnosis of Pulsatile Tinnitus (Whooshing Sound in Ear)

Primary Diagnostic Categories

Pulsatile tinnitus has an identifiable structural or vascular cause in over 70% of cases, making imaging evaluation essential in nearly all patients to avoid missing life-threatening conditions like dural arteriovenous fistula or arterial dissection. 1

Arterial Causes

• Atherosclerotic carotid artery disease is the single most common cause, accounting for 17.5% of cases, resulting from turbulent flow through stenotic vessels 1, 2
• Arterial dissection represents a potentially catastrophic condition requiring urgent anticoagulation/antiplatelet therapy and immediate identification 1, 3
• Fibromuscular dysplasia and carotid aneurysms can generate audible turbulent flow 4

Arteriovenous Causes

• Dural arteriovenous fistulas (AVF) account for 8% of cases and can lead to hemorrhagic or ischemic stroke if untreated—this is a life-threatening diagnosis that requires high clinical suspicion 1, 5
• Arteriovenous malformations (AVMs) create abnormal high-flow vascular connections producing continuous pulsatile tinnitus synchronized with cardiac cycle 1

Venous Causes

• Idiopathic intracranial hypertension (IIH) is the second most common cause overall, particularly in young overweight women with headaches, and can cause permanent vision loss if missed 1, 2
• Sigmoid sinus diverticulum or dehiscence is commonly associated with intracranial hypertension 1
• Jugular bulb abnormalities including high-riding jugular bulb or dehiscence of the sigmoid plate 1
• Aberrant venous anatomy including persistent petrosquamosal sinus and abnormal emissary veins 1

Vascular Tumors

• Paragangliomas (glomus tympanicum/jugulare) account for 16% of cases and appear as vascular retrotympanic masses on otoscopy 1, 5
• Adenomatous middle ear tumors are less common vascular masses 1

Structural/Bony Causes

• Superior semicircular canal dehiscence is a bony defect allowing transmission of vascular sounds into the inner ear 1
• Otosclerosis and Paget disease can cause increased bone vascularity 4

Systemic Causes

• Hypertension, cardiac arrhythmias, hyperthyroidism can amplify normal vascular sounds 2

Critical Clinical Distinctions

Objective vs. Subjective Tinnitus

• Objective pulsatile tinnitus (audible to examiner with stethoscope) is rare and strongly suggests vascular pathology requiring immediate workup 1
• Subjective pulsatile tinnitus (patient only) still warrants comprehensive imaging in nearly all cases 1

Laterality

• Unilateral pulsatile tinnitus has higher likelihood of identifiable structural or vascular cause compared to bilateral 1

Compression Test Findings

• Tinnitus relieved by carotid or jugular compression suggests venous etiology (sigmoid sinus abnormalities, jugular bulb variants) or arterial dissection 1, 3

Initial Clinical Assessment

Essential Physical Examination Findings

• Otoscopic examination to identify vascular retrotympanic masses (paragangliomas appear as pulsatile red/blue masses behind tympanic membrane) 3
• Auscultation over mastoid, periauricular area, orbit, and neck to detect objective bruit 3, 6
• Jugular/carotid compression test during auscultation—relief suggests venous or arterial dissection etiology 3
• Neurologic examination for focal deficits suggesting intracranial pathology or signs of increased intracranial pressure 3

Required Audiologic Testing

• Comprehensive audiologic examination (pure tone audiometry, speech audiometry, acoustic reflex testing) within 4 weeks to document asymmetric hearing loss indicating retrocochlear pathology 3

Imaging Strategy

First-Line Imaging Selection

If vascular retrotympanic mass visible on otoscopy:

• High-resolution CT temporal bone (non-contrast) to identify paragangliomas, glomus tumors, jugular bulb abnormalities, superior semicircular canal dehiscence, and aberrant vascular anatomy 1, 3

If otoscopy is normal:

• CT angiography (CTA) head and neck with contrast using mixed arterial-venous phase (20-25 seconds post-contrast) to capture both arterial and venous pathology in single acquisition 1, 3
• CTA identifies dural AVF, arterial dissection, atherosclerotic carotid disease, sigmoid sinus diverticulum/dehiscence, and AVMs 3

Second-Line Imaging

• MRI brain with contrast and MR angiography (MRA) when CT/CTA are negative but clinical suspicion remains high, to evaluate for cerebellopontine angle lesions and subtle vascular malformations 3
• Specialized internal auditory canal protocols with thin-section heavily T2-weighted sequences for vascular loops and small vestibular schwannomas 3

Common Pitfalls to Avoid

Life-Threatening Missed Diagnoses

• Missing dural AVF is the most catastrophic error—this condition can present with isolated pulsatile tinnitus before hemorrhage and requires high index of suspicion with appropriate vascular imaging 1
• Dismissing pulsatile tinnitus as benign without imaging is inappropriate, as identifiable causes exist in >70% of cases 1
• Overlooking arterial dissection which requires immediate anticoagulation/antiplatelet therapy 3

Diagnostic Errors

• Inadequate otoscopic examination leads to delayed diagnosis of paragangliomas and inappropriate imaging selection 1
• Overlooking IIH particularly in young overweight women with headaches can result in permanent vision loss 1
• Ordering MRV alone is insufficient—CT temporal bone or CTA head and neck should be the initial study 1

Inappropriate Resource Utilization

• Ordering imaging for bilateral, symmetric, non-pulsatile tinnitus without localizing features represents low-yield, expensive testing 1