Figure 3.

Illustrative case to demonstrate diagnostic and intraoperative findings: a 40-year-old man presented with 6 years of left aural fullness, pulsatile tinnitus, vocal distortion, and hearing his eyeballs move in his left ear. Ocular vestibular-evoked myogenic potentials (VEMPs) indicated elevated amplitude responses to 500 Hz tone bursts [(A), 47.3 µV, normal range 0–17 µV] and cervical VEMPs with low thresholds in response to clicks [(B), 65 dB nHL, normal range ≥80 dB nHL], both suggestive of a third mobile window syndrome involving the left ear. High-resolution computed tomography imaging with 0.6-mm slice thickness demonstrated a dehiscence of the left superior semicircular canal when image reconstructions were made orthogonal to the plane of the superior canal [(C), Stenvers view] and in the plane of the superior canal [(D), Pöschl view]. He elected to proceed with surgery via middle cranial fossa approach. The dehiscence measured 5 mm × 1 mm [(E), yellow arrow] and was plugged with a combination of autologous materials including fascia, bone dust, and bone chips (F). The middle cranial fossa was resurfaced with hydroxyapatite cement. Autophony improved after surgery, hearing was preserved, and vestibular dysfunction was limited to the superior semicircular canal as determined by clinical head impulse testing in all semicircular canal planes.