New nomenclature for drug-induced movement disorders including tardive dyskinesia

Psychotropic agents are increasingly being prescribed by different specialty clinicians for a variety of psychiatric illnesses, making it necessary to improve understanding of the etiology, diagnosis, and management of drug-induced movement disorders (D-IMD) across medical specialties. Early descriptions of movement disorders were based on identifiable disease states such as parkinsonism, dystonia deformans, and Huntington's chorea, which introduced complicated and often overlapping nomenclature. This has hindered communication about, description of, and diagnosis of these drug-induced disorders. Research criteria for tardive dyskinesia, a specific, purposeless, involuntary, hyperkinetic, potentially persistent D-IMD, have varied, with relatively few data-driven conclusions available to support clinical decision-making. The differences in research criteria among published reports on rates of tardive dyskinesia with atypical antipsychotics make it difficult to find meaningful comparisons and conclusions between atypicals. A novel system for classifying D-IMD according to whether they are reversible or persistent, hypokinetic or hyperkinetic, and dystonic or nondystonic is proposed. This new classification system will provide clinicians and researchers across specialties a more precise language, which will hopefully improve the diagnosis of and research criteria for D-IMD.