Is a temporal CT (computed tomography) scan with contrast useful for diagnosing pulsatile tinnitus?

Temporal CT with Contrast for Pulsatile Tinnitus

CT angiography (CTA) of the head and neck with IV contrast is the recommended first-line imaging modality for evaluating pulsatile tinnitus, rather than a temporal CT with contrast alone. 1, 2

Optimal Imaging Approach for Pulsatile Tinnitus

First-Line Imaging Options

• CT angiography (CTA) of head and neck with IV contrast:

  • Provides excellent visualization of both arterial and venous pathologies
  • Can detect dural arteriovenous fistulas (dAVFs) with 90% sensitivity and specificity
  • Allows evaluation of both vascular structures and bony temporal bone anatomy
  • Enables detection of vascular variants, arteriovenous malformations, and dissections 1, 2

• Non-contrast temporal bone CT:

  • Appropriate when a vascular retrotympanic mass is visible on otoscopy
  • Excellent for identifying bony abnormalities such as:
    • Superior semicircular canal dehiscence
    • Sigmoid sinus wall abnormalities
    • High-riding jugular bulb
    • Otospongiosis
    • Paget disease 1

Why Temporal CT with Contrast Alone is Not Recommended

• No supporting literature: The 2023 ACR Appropriateness Criteria explicitly states "there is no relevant literature to support the use of CT temporal bone with IV contrast for evaluation of PT when otoscopy does not show a vascular retrotympanic lesion" 1
• Limited field of view: Cannot adequately assess neck vessels 1
• Unnecessary contrast: IV contrast is not needed for evaluating many temporal bone abnormalities that cause pulsatile tinnitus 1

Clinical Decision Algorithm

1. If otoscopy reveals a vascular retrotympanic mass:

   • Begin with non-contrast temporal bone CT 1

2. If otoscopy is normal:

   • Proceed with CTA head and neck with IV contrast 1, 2
   • Alternative: MRI/MRA if radiation or contrast concerns exist 1, 2

3. If initial imaging is inconclusive but clinical suspicion remains high:

   • Consider conventional angiography (DSA), especially if dAVF is suspected 1, 2, 3

Common Vascular Causes of Pulsatile Tinnitus

• Arteriovenous fistulas and malformations
• Vascular tumors (paragangliomas, glomus tumors)
• Sigmoid sinus wall abnormalities
• Carotid artery stenosis or dissection
• Intracranial hypertension
• Venous anomalies 2, 4

Important Considerations

• Pulsatile tinnitus requires both a functional hearing organ and a physical source of sound 4
• In one study, highly vascularized tumors (16%), venous variants/anomalies (14%), and vascular stenoses (9%) were the most common causes of pulsatile tinnitus 4
• Combined CT angiography and venography is particularly useful in otoscopically normal patients 5
• Avoid the pitfall of ordering temporal CT with contrast, as this provides incomplete evaluation and may lead to missed diagnoses 1

By following this evidence-based approach, clinicians can efficiently diagnose the underlying cause of pulsatile tinnitus and guide appropriate treatment to improve patient outcomes.