What imaging is recommended for intermittent pulsatile tinnitus?

Imaging Recommendations for Intermittent Pulsatile Tinnitus

CT angiography (CTA) of the head and neck with IV contrast is the recommended first-line imaging modality for evaluating pulsatile tinnitus, as it provides excellent visualization of both vascular structures and temporal bone anatomy. 1

Diagnostic Algorithm

Initial Evaluation

• If otoscopy reveals a vascular retrotympanic mass:
  • Begin with non-contrast temporal bone CT 1
• If otoscopy is normal:
  • Proceed with CTA head and neck with IV contrast 1

Alternative First-Line Options

• MRI with MR angiography (MRA) if:
  • Patient has contraindications to radiation exposure
  • Patient has contraindications to iodinated contrast
  • Pregnancy is present 1

Second-Line Imaging

• Conventional angiography (DSA) if:
  • Initial imaging is inconclusive but clinical suspicion remains high
  • Objective pulsatile tinnitus is present with inconclusive noninvasive imaging
  • Further characterization of dural arteriovenous fistula (dAVF) is needed 2, 1

Advantages of CTA for Pulsatile Tinnitus

• Detects vascular abnormalities with high sensitivity and specificity (90% for dAVFs) 1
• Allows evaluation of:
  • Arterial variants and pathologies (dissections, stenosis)
  • Venous abnormalities (sigmoid sinus wall anomalies, jugular bulb variants)
  • Dural arteriovenous fistulas
  • Bony abnormalities (superior semicircular canal dehiscence) 2, 1
• Dedicated temporal bone CT reconstructions can be created from CTA source images without additional radiation exposure 2

MRI/MRA Considerations

• Comparable accuracy to catheter angiography in small studies 2, 3
• Better characterizes the relationship between nerves and blood vessels 2
• Superior for evaluating:
  • Cisternal lesions
  • Auditory pathway masses
  • Intracranial vascular malformations 2
• In one study, MRI/MRA defined anatomical abnormalities that may contribute to pulsatile tinnitus in 63% of patients 4

Ultrasound Applications

• Carotid duplex/Doppler ultrasound is helpful for:
  • Evaluating extracranial carotid stenosis
  • Detecting elevated resistive indices suggesting intracranial vascular abnormalities 2, 1

Common Pitfalls to Avoid

• Failing to perform a thorough otoscopic examination before imaging
• Not considering both arterial and venous causes of pulsatile tinnitus
• Overlooking non-vascular causes (e.g., paragangliomas, otosclerosis)
• Ordering unnecessary imaging for non-concerning tinnitus presentations 1
• Relying solely on CT or MRI without angiographic components, as many vascular lesions are seen best (46%) or only (36%) on angiographic studies 3

Important Clinical Considerations

• Pulsatile tinnitus requires both a functional hearing organ and a physical source of sound 5
• Common causes include:
  • Vascular abnormalities (arteriovenous malformations/fistulas, venous diverticulum)
  • Highly vascularized temporal bone tumors (16% in one series)
  • Venous normal variants and anomalies (14%)
  • Vascular stenoses (9%)
  • Dural arteriovenous fistulae (8%)
  • Intracranial hypertension (8%) 1, 5

When evaluating intermittent pulsatile tinnitus, a systematic imaging approach using CTA as the first-line modality, with appropriate alternatives based on patient-specific factors, provides the most comprehensive evaluation for identifying the underlying cause.