Transient mutism after posterior fossa surgery.

An 8-year-old girl developed mutism after removal of a vermian medulloblastoma. The mutism was not accompanied by long tract signs or cranial nerve palsy. The girl started to regain her speech 2 weeks postoperatively, showing marked improvement 2 months after the operation, after passing through a dysarthric phase. Magnetic resonance imaging showed only normal postoperative changes without abnormalities of dentate nuclei or supranuclear region. Nineteen similar cases of transient mutism following cerebellar operations have been reported in the literature, most of them with a delayed postoperative onset. In all patients the recovery of speech started to appear 4 days to 4 months postoperatively, and all patients passed through a monotonous, dysarthric phase. The absence of long tract or other brain stem signs, together with the presence of dysarthria during the recovery of speech, suggested a cerebellar cause of the transient mutism. Various hypotheses advanced to explain the pathogenesis of this speech disorder are analyzed.