Long-term adaptive changes of the vestibulo-ocular reflex in patients following acoustic neuroma surgery

A series of 26 patients undergoing translabyrinthine acoustic neuroma surgery was evaluated pre- and postoperatively using rotatory vestibular testing. Patients were tested immediately prior to surgery and followed long-term at frequent intervals for periods of one week to two years, depending on availability and length of time postoperative. Rotatory testing was performed at multiple frequencies of 0.0125, 0.05, and 0.2 Hz, and the vestibulo-ocular reflex was measured using electro-oculographic techniques. Dependent variables of the slow component of the vestibulo-ocular reflex were derived by computer analysis, including gain, phase, DC bias, ampullopetal and ampullofugal responses of the remaining labyrinth, and asymmetry. These variables changed in a predictable fashion as related to the reciprocal of time. Results of this data are fitted with a linear statistical model, validating the changes.