Cerebellar encephalomalacia on magnetic resonance imaging after removal of acoustic tumor.

MRI is widely used for postoperative surveillance of patients undergoing surgery for removal of acoustic neuroma. The purpose of this study was to investigate the frequency and pattern of postoperative changes in the cerebellum and brain stem on MRI after removal of acoustic neuroma. A retrospective study was conducted in 30 consecutive patients who underwent postoperative MRI between 1994 and 1995. The timing of the scans after surgery ranged from 12 months to 10 years. T2 -weighted turbo spin-echo images revealed cerebellar encephalomalacia in 17 of 30 cases. Cerebellar encephalomalacia was found more consistently in patients who had large tumors and was more frequent after the suboccipital approach. Encephalomalacia is largely caused by gliotic changes in the adjacent cerebellar tissues after tumor removal.