trainee · clinical case

Translabyrinthine schwannoma resection nine months ago

Vignette

A 60-year-old man who underwent a left translabyrinthine resection nine months ago reports near-normal function. SHA shows symmetric gain within the normal band and almost no phase lead. Caloric testing shows complete left areflexia.

RCT pattern

Gain · eye / chair00.601.200.010.020.040.080.160.320.64frequency (Hz, log)Phase lead · degrees-2030800.010.020.040.080.160.320.64frequency (Hz, log)Symmetry · %-500500.010.020.040.080.160.320.64frequency (Hz, log)
Three-panel SHA summary. Shaded green = published normal band. Solid marker = patient/archetype curve; dashed = overlaid reference if shown.

Question

How can SHA look normal when the left labyrinth is gone?