the significance of masseter muscle rigidity (MMR)?
MMR (trismus) has been reported to occur in 1%
of children receiving halothane and succinylcholine for induction. It was
previously thought to herald the onset of MH in 50% of cases as confirmed by
skeletal muscle biopsy. Recent studies indicate that MMR may occur in otherwise
normal patients. In the presence of MMR, whether to continue anesthesia for
elective procedures and whether to discon-tinue triggering agents remains
controversial. Some suggest that the anesthetic may be safely continued, while
others suggest that all such episodes should be treated as MH until proven
otherwise by skeletal muscle biopsy.
Other causes of MMR include temporomandibular
joint dysfunction, myotonia, and rapid succinylcholine hydrolysis.