What vestibular-evoked myogenic potential (VEMP) findings are typical in superior canal dehiscence?

• A. Higher thresholds and reduced amplitudes
• B. VEMP responses become inverted (negative) due to canal plugging
• C. No change in thresholds
• D. Lower thresholds and higher amplitudes

Answer: (D)

A sudden third window in the inner ear from superior canal dehiscence makes the vestibular system unusually sensitive to sound and pressure. VEMP tests tap the reflexes that originate from otolith organs (cVEMP from the saccule and neck muscles, oVEMP from the utricle and eye muscles). When there is a dehiscence, acoustic energy and vibration more readily reach these otolith receptors, especially at low frequencies, so responses appear at lower stimulus levels and with larger amplitudes. In practice, you’ll see reduced thresholds for eliciting VEMP responses and bigger response amplitudes, which is a classic hint pointing toward superior canal dehiscence. This pattern helps distinguish SCD from other vestibular issues where thresholds and amplitudes would not show this low-threshold, high-amplitude change.