Pathological and Functional Alterations in the Vestibular Labyrinth Following Cryosurgery

Abstract

Definite pathologic changes were noted within the horizontal crista ampullaris after cryosurgery. The amount of damage was dependent upon the temperature of the crista during cooling. For example, when the horizontal crista was cooled to-70°C (intralabyrinthine temperature + 18°C) exudate was observed in the endolymphatic space. Electron microscopically, however, definite cellular damage (myelin figures) was detected primarily in the specialized cells (dark and light). Ruptures of the membranous wall of the crista was observed at cryosurgical dosage of-90°C (intralabyrinthine temperature + 13°C). Gross histological damage was noted when the horizontal crista was cooled to-120 and-190°C (intralabyrinthine temperature +5 and-6°C respectively). The functional (rotatory tests), ultrastructural and histologic results correlate extremely well. These results indicate that the critical cryosurgical threshold dosage necessary to alter the morphology and function of the semicircular canal system is approximately-70°C (intralabyrinthine temperature + 18°C).