What is the differential diagnosis of pulsatile tinnitus?

Differential Diagnosis of Pulsatile Tinnitus

Pulsatile tinnitus requires systematic evaluation for underlying vascular abnormalities, with the differential diagnosis categorized into arterial, arteriovenous, and venous causes, plus structural and metabolic etiologies that can be life-threatening if missed. 1, 2

Primary Diagnostic Categories

Vascular Causes (Most Common)

Arterial Etiologies:

• Atherosclerotic carotid artery disease - the most frequent cause, accounting for 17.5% of cases, resulting from turbulent flow 3, 1
• Arterial dissection - a potentially life-threatening condition requiring urgent identification 1
• Fibromuscular dysplasia - causing arterial stenosis and turbulent flow 4
• Aberrant carotid artery - anatomic variant causing pulsatile sound 3, 1

Arteriovenous Causes:

• Dural arteriovenous fistulas (AVF) - accounting for 8% of cases, can lead to hemorrhagic or ischemic stroke if untreated 1, 4, 2
• Arteriovenous malformations - high-flow vascular lesions 1
• Highly vascularized skull base tumors - most common cause in some series at 16%, including paragangliomas and glomus tumors 1, 4

Venous Etiologies:

• Idiopathic intracranial hypertension (pseudotumor cerebri) - second most common cause at 10%, associated with sigmoid sinus wall abnormalities [3, @14@, 1,2]
• Jugular bulb abnormalities - including high-riding jugular bulb or dehiscence of the sigmoid plate 1, 3
• Sigmoid sinus diverticulum or dehiscence - commonly associated with intracranial hypertension 1, 5
• Venous sinus stenosis - accounting for 9% of cases 4
• Aberrant venous anatomy - including persistent petrosquamosal sinus, abnormal condylar and mastoid emissary veins 1

Structural Causes

Neoplastic:

• Paragangliomas (glomus tympanicum/jugulare) - appear as vascular retrotympanic masses on otoscopy 1, 2
• Adenomatous middle ear tumors - less common vascular masses 1

Temporal Bone Abnormalities:

• Superior semicircular canal dehiscence - bony defect allowing transmission of vascular sounds 1
• Paget's disease - increased bone vascularity 3

Metabolic and Systemic Causes

• High cardiac output states - including hyperthyroidism, anemia, pregnancy 3, 2
• Systemic hypertension - exacerbating vascular turbulence 3
• Cardiac arrhythmias - creating irregular pulsatile sounds 3
• Ototoxic medications - contributing to perception of vascular sounds 2

Non-Vascular Mimics (Must Exclude)

• Palatal myoclonus - pulse-asynchronous clicking, objective on examination 1
• Tympanic myoclonus - middle ear muscle spasm 1
• Eustachian tube dysfunction - may create rhythmic sounds with breathing 1, 5

Critical Clinical Distinctions

Objective versus Subjective: Objective pulsatile tinnitus (audible to examiner) is rare and strongly suggests vascular pathology requiring immediate workup, while 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 6

Modifiable by neck pressure: Tinnitus relieved by carotid or jugular compression suggests venous etiology (sigmoid sinus abnormalities, jugular bulb variants) or arterial dissection 5

Common Pitfalls to Avoid

• Missing dural AVF: This life-threatening cause requires high index of suspicion and appropriate vascular imaging, as it can present with isolated pulsatile tinnitus before catastrophic hemorrhage 1, 2
• Dismissing pulsatile tinnitus as benign: Unlike non-pulsatile tinnitus, pulsatile tinnitus almost always requires imaging evaluation due to identifiable causes in >70% of cases 6, 2
• Inadequate otoscopic examination: Failure to identify vascular retrotympanic masses (paragangliomas) leads to delayed diagnosis and inappropriate imaging selection 1
• Overlooking intracranial hypertension: Particularly in young, overweight women with headaches, this treatable cause can lead to vision loss if missed 1, 3