Cerebellar mutism after posterior fossa surgery--two case reports.

Two adults (aged 71 and 74 years) developed cerebellar mutism after posterior fossa surgery for a mass lesion in the superior cerebellar hemisphere or upper vermis. Histological examination showed one was a hemangioblastoma, the other a metastatic brain tumor. The tumors were totally removed via the occipital transtentorial approach. Both patients developed mutism on the 2nd postoperative day, which persisted for 3-4 weeks and was followed within 2-4 months by cerebellar dysarthria. Thereafter, their condition improved. Transient cerebellar mutism usually occurs in pediatric patients after the removal of a mass lesion in the upper vermis. Cerebellar mutism in adults is rare. The predominance of cerebellar mutism in children may be attributable to the predilection for vermian tumor and their tendency to experience personality and behavioral changes after posterior fossa surgery.