In a patient with intermittent right‑sided pulsatile tinnitus, ear fullness, no jaw pain, and a prior temporomandibular joint diagnosis, will a superior semicircular canal dehiscence be visible on magnetic resonance angiography (MRA) or magnetic resonance venography (MRV)?

No, Superior Semicircular Canal Dehiscence Will Not Show Up on MRA/MRV

Superior semicircular canal dehiscence (SSCD) requires high-resolution CT temporal bone without contrast for diagnosis—MRA and MRV are designed to image blood vessels, not bony structures, and will miss this condition entirely. 1

Why MRA/MRV Cannot Detect SSCD

MRA and MRV are vascular imaging techniques that visualize blood flow in arteries and veins respectively. SSCD is fundamentally a bony defect—a dehiscence or thinning of the bone overlying the superior semicircular canal 2. These modalities simply do not image bone architecture with sufficient detail to detect such defects.

While older literature from 1994 3 and 2013 4 suggested MRI/MRA could be useful for pulsatile tinnitus evaluation, these studies focused on vascular causes of pulsatile tinnitus (dural AVFs, paragangliomas, vascular malformations). More recent evidence, including MRI FIESTA sequences, has been explored for SSCD 2, but high-resolution CT remains the gold standard 5.

The Correct Imaging Approach

For your patient with pulsatile tinnitus and suspected SSCD, order high-resolution CT temporal bone without IV contrast. 1

The 2023 ACR Appropriateness Criteria explicitly states:

• CT temporal bone without contrast readily diagnoses SSCD 1
• IV contrast is not needed for assessment of semicircular canal dehiscence 1
• High-resolution CT (HRCT) with multiplanar reconstruction in the plane of the superior semicircular canal is required for definitive diagnosis 5

Clinical Context for Your Patient

Your patient presents with:

• Intermittent right-sided pulsatile tinnitus
• Ear fullness
• Prior TMJ diagnosis

SSCD can cause both pulsatile tinnitus and aural fullness 5, 6. The diagnostic criteria require:

1. At least one symptom consistent with "third mobile window" pathophysiology (your patient has pulsatile tinnitus and fullness) 5
2. At least one physiologic test showing third mobile window transmission (low-frequency negative bone conduction on audiometry, enhanced VEMP responses, or eye movements with sound/pressure stimulation) 5
3. High-resolution CT demonstrating the dehiscence 5

Pitfalls to Avoid

• Do not order MRA/MRV expecting to see SSCD—you will get a negative study and still need CT
• Do not add IV contrast to CT temporal bone—it adds no diagnostic value for SSCD and increases cost/radiation 1
• If CT temporal bone is negative but vascular PT is still suspected, then consider CTA head and neck or MRA/MRV for vascular etiologies 1

When to Consider MRA/MRV Instead

MRA/MRV would be appropriate if you suspect vascular causes of pulsatile tinnitus such as:

• Dural arteriovenous fistulas
• Venous sinus stenosis
• Arteriovenous malformations
• Vascular dissection

However, even for comprehensive pulsatile tinnitus workup, CTA head and neck is generally preferred over MRA/MRV because it provides both vascular detail AND bony temporal bone detail on thin-section reconstructions 1.