Effects of Cochlear Prostheses on Vestibulo-Ocular Reflexes to Rotation

Abstract

This study addresses the following questions: What is the effect of implant surgery on the vestibulo-ocular reflex (VOR)? Does activation of the prosthesis affect the VOR? We studied the VOR elicited by rotary stimuli in 12 patients, six with a House 3M device, five with a Nucleus device, and one who sequentially had both devices. Nine of the 12 patients had VOR responses to rotation. Four of the nine had a decrement in the VOR associated with surgery and mild symptoms of dysequilibrium that lasted up to 1 week after surgery. No one had vestibular symptoms nor a decrement in the VOR during stimulation of the prosthesis at comfortable loudness. Rotational vestibular tests can quantify the VOR in some but not all cochlear prosthesis patients. The present surgical technique for implantation of scala tympani electrodes may cause a permanent reduction in the VOR to rotation in some patients.