Clinical differentiation between lethal catatonia and neuroleptic malignant syndrome.

Lethal catatonia, a syndrome described several decades before the advent of neuroleptic drugs, has been regarded by many investigators as clinically similar to, and perhaps indistinguishable from, neuroleptic malignant syndrome. However, published case reports of the two syndromes indicate differences in mode of onset, signs and symptoms, and outcome. Lethal catatonia often begins with extreme psychotic excitement, which, if persistent, can lead to fever, exhaustion, and death. Neuroleptic malignant syndrome begins with severe extrapyramidally induced muscle rigidity. Because lethal catatonia often requires neuroleptic treatment and neuroleptic malignant syndrome necessitates immediate cessation of neuroleptics, their early clinical differentiation is important.