Fasciculations after rattlesnake envenomations: a retrospective statewide poison control system study

Rattlesnake envenomation occasionally results in repetitive small-muscle fasciculations known as myokymia. We report the results of a retrospective inquiry of this phenomenon from a statewide poison center's database.

Data was obtained from a poison system database for the years 2000-2003, inclusive, for rattlesnake envenomation exposures coded as having fasciculations.

A total of 47 cases were identified, and nine other cases were found from previously published literature. There was no consistent temporal pattern by monthly analyses in incidence or proportion of reported snakebites with myokymia. All four of the reviewed cases with myokymia of the shoulders were intubated and none without it were intubated.

A review of four consecutive years of data revealed no pattern to correlate the incidence of fasciculations with the month. The development of respiratory failure associated with myokymia, sometimes despite antivenom, is a newly reported occurrence. Clinicians are reminded to monitor closely airway and inspiratory capacity in patients with severe myokymia.