Rhabdomyolysis and hyperthermia after cocaine abuse: a variant of the neuroleptic malignant syndrome?

Rhabomyolysis with myoglobinuria has been added relatively recently to the neurologic complications associated with the increased use of cocaine and the introduction of its alkaloid form (crack). This retrospective study reports our experience with 14 patients who presented with rhabdomyolysis after cocaine use in a municipal hospital over a 3-year period. Seven patients used "crack", 2 intravenous and 3 nasal insufflation. All patients but one had hyperthermia, 11 altered mental status, 8 tachycardia, and 4 muscle rigidity. Nine developed renal failure; 3 of these patients died. Two other patients died of cardiorespiratory arrest. Cocaine-related rhabdomyolysis has a high mortality. The observed association with hyperthermia and other central neurologic features resembles the neuroleptic malignant syndrome. Since chronic cocaine use may alter the availability of dopamine either through transmitter depletion or decrease in the number of dopamine receptors, a common pathogenetic mechanism is possible. However, other mechanisms, which are not mutually exclusive but rather frequently overlapping, may play an important role. These include agitation, hyperthermia, adrenergic overstimulation leading to vasoconstriction and ischemia or calcium release from the sarcoplasmic reticulum resulting in increased entry into the muscle cell leading to cell death; in addition, cocaine has direct toxic effect on the muscles.