AN ELECTROMYOGRAPHIC MARKER FOR NEUROLEPTIC-INDUCED AKATHISIA - PRELIMINARY MEASURES OF SENSITIVITY AND SPECIFICITY

Previous polysomnographic (PSG) investigations have reported a rhythmi c electromyographic (EMG) pattern (0.5-3.0 cps) of leg movement activi ty in a subset of patients with neuroleptic-induced akathisia (NIA). I t has been suggested that this EMG pattern may represent a pathophysio logical correlate of NIA and thus have clinical utility as an objectiv e marker for this condition. We present preliminary measures of sensit ivity and specificity for this EMG pattern as a diagnostic marker for NIA for 26 neuroleptic-treated patients. The EMG marker yielded a diag nostic sensitivity of 68.9% and a specificity of 70.0%, falling just s hort of statistical significance (Fisher's exact test p = 0.06). Quant itative analysis of the EMG pattern revealed a significant positive co rrelation between the percentage of time the NIA marker occurred durin g wakefulness and corresponding chlorpromazine equivalent levels. Clin ical demographic findings for true-positive, false-positive, true-nega tive, and false-negative groups are discussed. Overall findings sugges t that this particular pattern of EMG marker activity observed in neur oleptic-treated patients during PSG and EMG studies is valuable in fac ilitating the diagnosis and monitoring treatment of NIA.