Jama 2005;293:2918; Nejm 1993;329:484

Cause:Genetic plus anesthesia or other stress; autosomal dominant

Pathophys:Abnormal calcium channel in muscles causes Ca⁺⁺ release into muscles and intense contractions

Prevalence = 1/14000 people can develop if stressed; a history of 1 safe anesthesia is no guarantee next will be ok

Sx:None

Si:Intraoperatively tachycardia and tachypnea precede muscle rigidity and then high fever

High mortality

r/o neuroleptic malignant syndrome (Neuroleptic Malignant Syndrome); cocaine OD (Cocaine Use); and simpleHEAT STROKE(Nejm 2002;346:1979) with T° >40°C, impaired thermoregulation, cognitive impairment, and anhidrosis, 10% mortality; in the elderly or in healthy adults exercising in the heat (Nejm 1993;329:484)

Lab:

Chem:Platelet ATP studies distinguish? (Letter—Nejm 1980;303:642)

Path:Muscle bx of relatives shows abnormality in vitro responses to drug stimulation if they too are susceptible

Rx:Prevent by avoiding halogenated gases and muscle paralyzers; may try to prevent with dantrolene (Dantrium) 1 mg/kg po × 2 d prior to elective surgery; avoid calcium channel blockers

of acute attack: stop anesthesia; dantrolene (Dantrium) 1 mg/kg push, repeat up to response or 10 mg/kg