Six children, aged 6 to 12 years, who developed cerebellar mutism after surgery for a posterior fossa mass or as a result of trauma are reported from the Children’s Hospital, Los Angeles, CA. The incidence following posterior fossa tumor resection was 1.6%. Four had primitive neuroectodermal tumors (medulloblastoma), a fifth had mutism following trauma, and the sixth had an arteriovenous malformation. Hydrocephalus developed as a result of the tumor or AVM in 4 patients. Cerebellar mutism duration was 10 days in one patient and 2 to 8 weeks in the others. Dysarthria occurred during recovery in 4. Trauma to the dentate nucleus and/or the superior cerebellar peduncle is suggested as the cause of reversible mutism. 
COMMENT. Cerebellar mutism is reviewed in Progress in Pediatric Neurology III, 1997;pp306-307). This complication of posterior fossa tumor resection is correlated with the amount of posterior vermis resected, adherence of the tumor to the floor of the fourth ventricle, shunting for hydrocephalus prior to surgery, and postsurgical edema of the pontine tegmentum. More than 50 cases are cited in the literature.