Encephalopathy during amitriptyline therapy: are neuroleptic malignant syndrome and serotonin syndrome spectrum disorders?

This report describes a case of encephalopathy developed in the course of amitriptyline therapy, during a remission of unipolar depression. This patient could have been diagnosed as having either neuroleptic malignant syndrome (NMS) or serotonin syndrome (SS). The major determinant of the symptoms may have been dopamine/serotonin imbalance in the central nervous system. The NMS-like encephalopathy that develops in association with the use of antidepressants indicates that NMS and SS are spectrum disorders induced by drugs with both antidopaminergic and serotonergic effects.