Mutism immediately following removal of a large midline posterior fossa medulluloblastoma and a cerebellar arteriovenous malformation is reported in 2 children from the Department of Neurosurgery, University of Florida, Gainsville, FL. The 7 year old boy with medulluloblastoma showed only a mild dysarthria and truncal ataxia at 3 month follow up and a 15 year old girl with acute posterior fossa bleed and obstructive hydrocephalus was similarly affected by a dysarthria and truncal ataxia when examined at 3 months. A review of the literature disclosed 19 cases of transient mutism after surgical removal of posterior fossa tumors. The more widespread the injury to the midportion of the cerebellum with dentate nuclear involvement, the greater the risk of developing post-operative mutism. 
COMMENT. The authors advise that this possible complication of posterior fossa surgery should be discussed with patient and parents as part of the preoperative planning. Mutism is not restricted to tumor pathology but may be associated with any acute pathological insult to the midportion of the cerebellum. Fortunately, the mutism resolves completely or to a mild cerebellar dysarthria over a 3 month period. Surgery of midline medulloblastomas is particularly at risk for the development of postoperative mutism.