BILATERAL VESTIBULAR NEURECTOMY FOR TREATMENT OF VERTIGO

The effects of bilateral vestibular neurectomy on equilibrium and vest ibular function were clinically evaluated in two patients more than 15 years after surgery. Both patients had bilateral Meniere's disease an d their vertiginous spells were permanently resolved after the second vestibular neurectomy. Symptoms of disequilibrium were absent in one p atient and mild in the other. Reflexive horizontal eye movements on wh ole body rotation in darkness were absent on low angular accelerations (2-degrees/s2), but could be elicited with angular accelerations of 2 0-degrees/s2 or higher. Extravestibular cues generating these eye move ments seemed to be unlikely because a ''control'' patient with complet e peripheral vestibular ablation after bilateral subtotal petrosectomy did not present reflexive eye movements under the some stimulus parad igms. An incomplete deafferentiation of the vestibular end organ (rath er than regeneration of vestibular nerve fibers) and a consecutive imp airment of the central velocity storage mechanism may explain the good functional outcome in our bilateral neurectomized patients.