Coexisting tardive dyskinesia and parkinsonism: a case report

A case report is presented of a patient with remitting tardive dyskinesia coexistent with neuroleptic-induced parkinsonism. The patient received benztropine and physostigmine challenges on successive days and the effects on both syndromes are described. The clinical course of both diseases is discussed in terms of a balance hypothesis between dopaminergic and cholinergic neurotransmission.