BILATERAL VESTIBULAR NEURECTOMY FOR TREATMENT OF VERTIGO

The effects of bilateral vestibular neurectomy on equilibrium and vestibular function were clinically evaluated in two patients more than 15 years after surgery. Both patients had bilateral Meniere's disease and their vertiginous spells were permanently resolved after the second vestibular neurectomy. Symptoms of disequilibrium were absent in one patient and mild in the other. Reflexive horizontal eye movements on whole body rotation in darkness were absent on low angular accelerations (2-degrees/s2), but could be elicited with angular accelerations of 20-degrees/s2 or higher. Extravestibular cues generating these eye movements seemed to be unlikely because a ''control'' patient with complete peripheral vestibular ablation after bilateral subtotal petrosectomy did not present reflexive eye movements under the some stimulus paradigms. An incomplete deafferentiation of the vestibular end organ (rather than regeneration of vestibular nerve fibers) and a consecutive impairment of the central velocity storage mechanism may explain the good functional outcome in our bilateral neurectomized patients.