Increased activation effects of succinylcholine in neurological patients.

Succinylcholine, a depolarizing muscle relaxant with both activating and desensitizing effects, is used to facilitate endotracheal intubation. The activating effects were found to be above-normal on induction of anesthesia in 7 neurological patients: generalized muscle spasm in 1 myotonic patient, contractures or prolonged contractions in "anatomically" denervated muscles (1 patient), in "functionally" denervated muscles (1 patient) and in "centrally" denervated muscles (4 patients). One of these four presented hyperkalemia and cardiocirculatory collapse. It is important to differentiate these anomalous responses to succinylcholine from those occurring as early signs of rhabdomyolysis or malignant hyperthermia.