A 38-year-old woman has vertigo triggered by loud noises and by straining during Valsalva, with pulsatile tinnitus and conductive-type hearing loss. Audiometry shows low-frequency air-bone gap with normal acoustic reflexes. Which investigation will definitively confirm the suspected diagnosis?

• A High-resolution thin-section CT scan of the temporal bone ✓
• B MRI of the internal auditory canal with gadolinium
• C Electrocochleography showing elevated SP/AP ratio
• D Video head impulse test showing bilateral catch-up saccades

Explanation

Tullio phenomenon (sound-induced vertigo) with Valsalva-induced vertigo, low-frequency air-bone gap with preserved acoustic reflexes, points to superior semicircular canal dehiscence. The definitive confirmation is a high-resolution CT of the temporal bone with very thin sections, around 0.5 mm, reformatted along the plane of the superior canal, demonstrating absence of bone over the arcuate eminence. MRI cannot reliably show the bony dehiscence, and the raised SP/AP ratio belongs to Meniere's disease.

Reference: Cummings Otolaryngology: Head and Neck Surgery, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.