What is the recommended diagnostic approach for a patient presenting with intermittent pulsatile tinnitus?

Diagnostic Approach for Intermittent Pulsatile Tinnitus

For patients with intermittent pulsatile tinnitus, dedicated temporal bone CT is recommended as a first-line imaging study to identify potential vascular causes, followed by CT angiography (CTA) or MR angiography (MRA) if needed. 1, 2

Initial Evaluation

• Determine if tinnitus is truly pulsatile: Confirm synchronization with heartbeat
• Assess if objective or subjective:
  • Objective: Examiner can hear the sound with auscultation
  • Subjective: Only patient perceives the sound
• Otoscopic examination: Look for retrotympanic mass, vascular abnormality, or middle ear fluid
• Auscultation: Listen over the ear, mastoid, and neck for bruits

Imaging Algorithm

First-Line Imaging

• Dedicated temporal bone CT: Recommended initial study 1
  • Identifies:
    • Paragangliomas (glomus tumors)
    • Adenomatous middle ear tumors
    • Vascular variants
    • Semicircular canal dehiscence
    • Sigmoid plate or jugular bulb dehiscence

Second-Line Imaging (if temporal bone CT is negative or inconclusive)

• CT angiography (CTA) of head and neck: 1, 3

  • Advantages:
    • Can create temporal bone reconstructions from source images
    • Evaluates arterial and venous anatomy
    • Identifies vascular variants, dural arteriovenous fistulas (AVF), arterial dissection
    • Detects sigmoid sinus wall anomalies associated with intracranial hypertension

• MR angiography (MRA): 1, 2

  • Comparable accuracy to catheter angiography in small studies
  • Preferred for pregnant patients (non-contrast MRA)
  • Better characterizes relationship between nerves and blood vessels
  • Useful for patients with contraindications to iodinated contrast

Third-Line Imaging

• Conventional angiography (DSA): 1, 4

  • Reserved for:
    • Objective pulsatile tinnitus with inconclusive noninvasive imaging
    • Subjective pulsatile tinnitus with high suspicion for vascular etiology
    • Further characterization of dural AVF
    • Differentiation between paraganglioma and middle ear adenomatous tumors

• Carotid duplex/Doppler ultrasound: 1, 2

  • Helpful for evaluating extracranial carotid stenosis
  • Alternative when other imaging is contraindicated
  • Can detect elevated resistive indices suggesting intracranial vascular abnormalities

Common Etiologies to Consider

• Vascular abnormalities: 1, 5

  • Arteriovenous malformations or fistulas
  • Venous diverticulum with stricture
  • Transverse/sigmoid sinus stenosis
  • Dominant venous system
  • Carotid artery stenosis or dissection

• Vascular tumors: 6, 7

  • Glomus tympanicum
  • Glomus jugulare

• Other causes: 1, 5

  • Idiopathic intracranial hypertension
  • Otosclerosis
  • Superior semicircular canal dehiscence
  • Patulous eustachian tube

Important Caveats

• Pulsatile tinnitus often represents a treatable condition and should never be dismissed without proper evaluation 2, 5
• Many vascular etiologies can be managed endovascularly, leading to improvement or resolution 5
• Venous sinus stenting is an emerging therapy for pulsatile tinnitus secondary to idiopathic intracranial hypertension with venous sinus stenosis 5
• Failure to identify serious vascular malformations like dural arteriovenous fistulas can result in significant morbidity and mortality 4
• Up to 63% of patients with subjective pulsatile tinnitus have identifiable anatomical abnormalities on MRI/MRA 4

Remember that pulsatile tinnitus differs significantly from non-pulsatile tinnitus in its diagnostic approach and potential serious underlying causes, requiring appropriate imaging in all cases.