Lethal catatonia and neuroleptic malignant syndrome. A dopamine receptor shut-down hypothesis.

BACKGROUND: Lethal catatonia and neuroleptic malignant syndrome (NMS) have been suggested to have a common neurochemical cause. We hypothesise that both conditions may be due to a sudden and massive blockade of dopamine neurotransmitters.

METHOD: NMS was diagnosed in psychotic in-patients treated with neuroleptics if four features were present: diffuse severe rigidity, altered level of consciousness, hyperpyrexia and autonomic instability.

RESULTS: Over three years, five NMS cases were diagnosed. Two presented with catatonic features and were diagnosed as acute reactive psychosis. Their neuroleptic doses were small, arguing for a particular sensitivity in these two cases.

CONCLUSION: The sensitivity of two patients with catatonic features who developed NMS with small doses of neuroleptics supports a common neurochemical basis for the two conditions.