Malignant hyperthermia, neuroleptic malignant syndrome and heat stroke: spectrum of a clinical syndrome

Malignant hyperthermia [MH] is a rare disease which occurs in genetically susceptible subjects after exposure to certain anaesthetics. The triggering anaesthetic agent causes abnormal release or re-uptake of calcium Ca[2+] from the sarcoplasmic reticulum. This interferes with the contraction relaxation process with a progressive increase in heat production and reduction of ATP levels. Neuroleptic malignant syndrome [NMS] is an uncommon disorder and occurs after administration of a neuroleptic agent or acute withdrawal of dopamine therapy. This leads to reduced central dopaminergic drive in the striatum and hypothalamus, so, extrapyramidal muscle rigidity with progressive generation of heat occurs. Heat stroke [HS] is due to the transfer of heat from the environment to the body core. This leads to a major insult to the hypothalamus, the temperature thermostat of the body, so there is a progressive increase in body temperature. There are similarities in the pathogenesis, biochemical changes, clinical pictures, complications and accordingly, the management of these potentially fatal syndromes. Dopaminergic agents and bromocriptine are effective in NMS but of no use in MH or HS. Dantrolene, an inhibitor of calcium release from the sarcoplasmic reticulum is the specific treatment for MH. It has also been used successfully in NMS and HS especially if rhabdomyolysis has occurred