What is the condition characterized by muscle rigidity, fever, altered mental status, and unstable blood pressure in a patient taking antipsychotics?

The condition characterized by muscle rigidity, fever, altered mental status, and unstable blood pressure in a patient taking antipsychotics is known as Neuroleptic Malignant Syndrome (NMS). This syndrome typically arises as a serious side effect of antipsychotic medications, particularly typical antipsychotics, and can occur after the initiation of treatment, dosage increases, or after the withdrawal of antipsychotics.

NMS is a life-threatening emergency, marked by the rapid onset of severe muscle rigidity and hyperthermia, as well as autonomic instability, which manifests as changes in blood pressure and heart rate. Patients may also experience confusion, altered consciousness, and agitation, reflecting the significant impact on the central nervous system. The underlying mechanism involves dopamine receptor antagonism, which disrupts the normal regulation of muscle tone and temperature.

This syndrome is distinct from other conditions often discussed in the context of antipsychotic medications. For instance, serotonin syndrome primarily stems from excess serotonin and presents with different symptoms such as myoclonus, hyperreflexia, and gastrointestinal distress. Extrapyramidal symptoms (EPS), like tremors or akathisia, involve abnormal motor control but do not typically include the high fever and autonomic instability characteristic of