“Ms. S.M.,” a 47-year-old woman with a severe organic brain disorder, was in therapy with ziprasidone 160 mg/day, valproate sodium 1,500 mg/day, and clonazepam 6 mg/day. Because of the persistence of psychotic symptoms, 800 mg/day quetiapine was administered, and ziprasidone was withdrawn. Because of distal upper limb tremor, the patient received biperiden 4 mg/day. One month later, sertraline was administered, at 200 mg/day because of the worsening of obsessive-compulsive behavior. Five days after the increase in sertraline dosage, the patient experienced severe PS despite the biperiden treatment. On hospitalization, no abnormalities were observed in hematochemical parameters, electrochardiography and urine analyses. Evaluation of extrapyramidal symptoms (EPS), using the Simpson–Angus Scale (SAS),4 yielded a score of 28 (Table 1). Sertraline was discontinued, and quetiapine reduced to 400 mg/day. The other treatments were maintained. The PS significantly declined in 4 days (SAS score: 11), and the patient was discharged. After 15 days the patient was re-evaluated, and the SAS score was 6 (Table 1).