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.