A 49-year-old woman has had four episodes of rotational vertigo lasting 2–4 hours over the past 6 months, each accompanied by left-sided aural fullness and roaring tinnitus. Audiometry shows a fluctuating low-frequency sensorineural hearing loss in the left ear (35 dB HL at 250 and 500 Hz, normal at 2–8 kHz). She has been symptom-free for the past 3 weeks.

Investigations

Which feature is most consistent with this clinical picture?

• AFrequency-tuning shift on the left (best response at 1 kHz instead of 500 Hz)
• BLowered cVEMP threshold on the left
• CAbsent oVEMP on the left
• DProlonged P1 latency on the left