THE MARYLAND-PSYCHIATRIC-RESEARCH-CENTER SCALE AND THE CHARACTERIZATION OF INVOLUNTARY MOVEMENTS

The Maryland Psychiatric Research Center involuntary movement scale (M PRC scale) has been used in the evaluation of 1107 patients referred f or drug-induced movement disorders. The scale has increased discrimina tion of body area and severity compared to other scales. Validity was examined using principal component analyses, pharmacologic response st udies and associations with AIMS, global judgement and motor diagnosis . Reliability was examined using Cronbach's alpha, intraclass correlat ion coefficient (ICC) between raters and test-retest measurements. The prevalence of dyskinetic and parkinsonian signs at several levels of severity are reported. Total dyskinesia was strongly correlated with A IMS score, r = 0.97. Inter-rater reliability was 0.81-0.90 for total d yskinesia score. Receiver Operating Characteristic (ROC) analysis show s a total dyskinesia score of 4 or above to predict tardive dyskinesia , consistent with RDC-TD criteria. Hand dyskinesia showed a high preva lence comparable to that of oral dyskinesias. The MPRC scale is a vali d, sensitive and reliable instrument for the rating of neuroleptic-ind uced dyskinetic and parkinsonian syndromes and may offer advantages ov er other scales in neurophysiologic research and brain imaging with it s ease of use, uniform structure and greater discrimination of anatomi c place and severity in the rating of involuntary movements. (C) 1997 Elsevier Science Ireland Ltd.