Vestibular findings in patients with acoustic neurinoma.

We studied the vestibular system of 30 patients with eighth nerve schwannoma. Preoperatively, cold and warm calorizations were performed. At operation, the utriculus and the ampulla of the horizontal semicircular canal as well as the eighth nerve were identified and removed for study. The sensory epithelium of utricular macula and ampullar crista appeared fairly normal in most cases. In one, there was tumor invasion to the labyrinth and in another patchy necrosis of the sensory epithelium. The number and quality of sensory cells varied from case to case. In cases with intact superior vestibular nerve, on light microscopy the histopathologic features of sensory epithelia did not differentiate between groups and symmetrical caloric reactions and with reduced or absent caloric reactions.