Clinical Relevance of Quantitative Measurements of Drug-induced Extrapyramidal Symptoms

We devised and tested a simple and practical measuring system for assessing drug-induced extrapyramidal signs (EPS) in schizophrenic patients. We first assessed the ability of the system to clinically measure the degree of EPS, and then investigated differences between conventional and atypical antipsychotic agents. Schizophrenic patients (28 males, 22 females) were compared with age-matched normal controls. A 14-item battery of measurements was analyzed in terms of established EPS scale scores and psychiatric symptoms. Measurements concentrated on the face, upper and lower limbs. Patients were impaired in 10 out of 14 quantitative subtests concerning movements when compared with normal controls. Facial characteristics that differed between patients and normal controls included oral agility and Myerson's sign; for the upper limbs included various fine, dominant-handed tasks; and for the lower limbs included gait. We then compared 16 patients receiving conventional agents and 18 patients receiving atypical agents, using the same system. Improvements in oral agility and fine finger movements were observed for patients on newer atypical agents. Our measurement system can reveal motor dysfunction and difficulties that cause problems in daily life for schizophrenic patients, and therefore provides a clinically useful assessment of drug-induced EPS. The most sensitive subtests for detecting drug-induced side effects were those that dealt with oral agility and rapid, repetitive finger movements.