Tardive dyskinesia with inflated neurons of the cerebellar dentate nucleus. Case reports and morphometric study.

Four autopsied cases of tardive dyskinesia manifesting oral hyperkinesia revealed markedly inflated neurons in the cerebellar dentate nucleus (DN), which had not been described previously. The inflation of the neurons was proved to be statistically significant (P less than 0.01) by morphometric study. The nuclei were usually situated in the central portion of the cytoplasm. This inflated change was different from both central chromatolysis and grumose degeneration of the DN, typically observed in progressive supranuclear palsy and dentatorubropallidolysian atrophy, and seemed to be easy to miss without careful observation, since neuronal loss and gliosis were very mild in the DN. Among a few autopsied cases of tardive dyskinesia reported previously, degeneration of the DN was described in only two. It is believed, however, that the inflated neurons of the DN may not be so rare and may be related to the occurrence of some involuntary hyperkinesia, especially oral hyperkinesia following some neurotoxic disorders and/or neuroleptic medications.