The present report of two fatal awake malignant hyperthermia (MH) episodes in an malignant hyperthermia susceptible family is intended to raise awareness among medical personnel and malignant hyperthermia susceptible individuals to the possibility of life-threatening non-anesthesia-triggered malignant hyperthermia episodes and to provide a strong incentive for development of effective preventive measures.
Two young athletic males (28 and 16 yr old), members of the same extended family with a history of anesthesia-related malignant hyperthermia episodes and deaths.
They succumbed ten years apart on two different continents, with symptoms unrelated to anesthesia but strikingly similar to typical anesthetic-induced malignant hyperthermia.
Both suffered an abrupt surge in body temperature, tachycardia, tachypnea, muscle rigidity, hyperkalemia, and respiratory and metabolic acidosis.
Despite aggressive resuscitation attempts, both developed cardiac arrest and died shortly upon arrival to hospital emergency departments. Autopsy analyses were negative for drugs, alcohol, or bacterial infection. Individual and familial genetic analyses revealed a novel, potentially pathogenic RYR1 variant (p.Gly159Arg) that co-segregates with the malignant hyperthermia susceptible phenotype in the family. Both fatal awake malignant hyperthermia episodes are hypothesized to have been triggered by physical exertion compounded with a febrile illness that in one case was due to influenza type A.
Life-threatening awake malignant hyperthermia episodes may develop in some malignant hyperthermia susceptible individuals in the absence of anesthetic triggers. Potential triggers can be physical exertion in combination with a febrile illness. Malignant hyperthermia susceptible patients are recommended to be vaccinated against flu and restrict physical activities when febrile, wear an malignant hyperthermia alert bracelet, and inform medical personnel of their malignant hyperthermia history. Oral dantrolene is suggested to be available to malignant hyperthermia susceptible patients for administration with the early signs of awake malignant hyperthermia .