Does peripheral neuropathy allow for the clinical expression of tardive dyskinesia by unmasking central nervous system changes?

Tardive dyskinesia (TD) is a severe and troubling complication of long-term typical neuroleptic use whose etiology remains obscure. While it is widely believed that central nervous system (CNS) dopamine receptor supersensitiv ity is involved in the pathogenesis of the condition, it is unclear why som e patients develop TD while others do not. It is proposed that a subclinica l peripheral motoneuropathy with consequent enlarging of the motor units ma y act to unmask neuroleptic-induced CNS changes allowing for the expression of TD. To investigate this hypothesis we examined motor unit size with ele ctrographic examinations in 14 patients (six with mild TD; eight without an d all with psychotic illness). There were no differences between the two gr oups of patients. While the data do not appear to support the hypothesis, a larger study with more severely affected patients is required to more adeq uately test the hypothesis. (C) 2001 Harcourt Publishers Ltd.