What causes pulsatile tinnitus?

Causes of Pulsatile Tinnitus

Pulsatile tinnitus is most commonly caused by vascular abnormalities including arterial disorders (arteriosclerosis, dissection, fibromuscular dysplasia), arteriovenous conditions (dural arteriovenous fistulae, highly vascularized skull base tumors), and venous disorders (intracranial hypertension, venous anomalies). 1, 2

Classification of Pulsatile Tinnitus Causes

Pulsatile tinnitus can be categorized into three main groups based on the site of generation:

1. Arterial Causes

• Arteriosclerosis and vascular stenoses (9% of cases) 2
• Arterial dissection 2
• Fibromuscular dysplasia 2
• Aberrant carotid artery 3
• Intracranial aneurysms (rare) 3

2. Arteriovenous Causes

• Arteriovenous fistulae (8% of cases) 2
• Highly vascularized skull base tumors (16% of cases - most common cause) 2
• Arteriovenous malformations (less than 1% of cases) 4
• Glomus tumors 3

3. Venous Causes

• Intracranial hypertension (8% of cases) 2
• Venous normal variants and anomalies (14% of cases - second most common cause) 2
• Dehiscent jugular bulb 3
• Multiple dilated venous channels 4

4. Other Categories

• Structural causes:
  • Temporal bone pathologies 5
  • Neoplasms 5
• Metabolic causes:
  • Ototoxic medications 1
  • Systemic conditions causing high cardiac output 5
• Inflammatory causes:
  • Inflammatory hyperemia (8% of cases) 2

Diagnostic Approach

The American Academy of Otolaryngology-Head and Neck Surgery recommends the following imaging modalities for pulsatile tinnitus 1:

• CT angiography or MR angiography for pulsatile tinnitus
• MRI with contrast of internal auditory canals for unilateral tinnitus with asymmetric hearing loss
• MRI brain with contrast for focal neurological findings

Important Clinical Considerations

• Unlike non-pulsatile tinnitus, pulsatile tinnitus usually has an identifiable cause in more than 70% of cases 5
• Pulsatile tinnitus requires both a functional hearing organ and a physical source of sound 2
• Pulsatile tinnitus can be a warning sign of potentially serious vascular conditions that may lead to hemorrhagic or ischemic stroke 5
• Immediate ENT referral is recommended for all cases of pulsatile tinnitus due to potential underlying serious conditions 1

Common Pitfalls to Avoid

• Failing to perform appropriate vascular imaging studies in patients with pulsatile tinnitus 1
• Missing red flags that warrant urgent evaluation 1
• Overlooking non-otologic causes of pulsatile tinnitus 1
• Incomplete evaluation that fails to identify treatable causes 1
• Evaluating imaging studies without considering clinical findings (both must always be evaluated together) 2

The thorough evaluation of pulsatile tinnitus is critical as it can reveal treatable causes and potentially life-threatening conditions that require immediate intervention.