Olanzapine-induced atypical neuroleptic malignant syndrome in an adolescent man with anorexia nervosa.

Anorexia nervosa (AN) is a serious mental illness that causes significant physical, emotional, cognitive, and social impairments. AN most often develops during adolescence or young adulthood and has high mortality and morbidity rates, in addition to cost burden. Current treatment of AN is multidisciplinary and is typically with a combination of medical, nutritional, and psychological interventions [1] . Antipsychotic medications have been especially used for weight gain and to treat body focused delusional thoughts in adolescent patients with AN [2]. Olanzapine is the most prominent second-generation antipsychotics (SGA) used for the treatment of this condition. However, although it is reported that these drugs are safe to use in adolescents with AN, side effects such as neuroleptic malignant syndrome (NMS) may vary in both the presenting and progressing features in patients with AN. NMS is a rare, idiosyncratic, and potentially fatal complication of antipsychotic medication. Cardinal features of NMS are muscle rigidity, hyperthermia, autonomic instability, and altered mental state. Laboratory findings are non-specific, but leukocytosis is common, and the levels of creatine kinase (CK) are often elevated. Approximately 66 % of NMS cases develop within the first week of initiating of antipsychotic treatment or a change of dose, and almost all cases develop within 30 days [1]. We report a case of an adolescent man with AN, who developed symptoms consistent with NMS after 2 days of treatment with a low dose of olanzapine, and although the symptoms of NMS had been resolved, these symptoms recurred after a month.