Related Experiment Videos
Masseter muscle rigidity and malignant hyperthermia susceptibility
Abstract:
Seventy-seven patients who developed masseter muscle rigidity (MMR) after receiving succinylcholine to facilitate tracheal intubation were evaluated for malignant hyperthermia (MH) susceptibility by in vitro halothane and caffeine contracture tests. Thirty-nine patients were diagnosed as MH-susceptible. Neither age, sex, nor type of surgery or anesthesia distinguished MH-susceptible from nonsusceptible patients. Two susceptible and two nonsusceptible patients had evidence of a myopathy. Fifty-two patients had serum creatine phosphokinase (CPK) levels measured in the perioperative period. Although all values were above normal, CPK values equal to or greater than 20,000 IU within 24 hr of trismus (in the absence of myopathy) were observed in six of 30 patients diagnosed as MH-susceptible, but were found in none of the nonsusceptible patients. Considering the high percentage of patients exhibiting MMR that are indeed susceptible to MH (approximately 50%) compared to estimates of MH in the population as a whole (approximately 0.005%), MMR should be considered a presumptive sign of MH. Perioperative CPK values greater than 20,000 IU are highly suggestive of MH susceptibility. Patients exhibiting MMR should be evaluated for MH susceptibility and myopathies. Succinylcholine should be avoided for subsequent anesthetics in patients with a history of MMR.
Insights
Masseter muscle rigidity (MMR) after succinylcholine is a strong indicator of malignant hyperthermia (MH) susceptibility. Patients with MMR should be tested for MH and myopathies, and succinylcholine avoided in future anesthetics.
Area of Science:
- Anesthesiology
- Pharmacology
- Genetics
Background:
- Malignant hyperthermia (MH) is a rare, life-threatening pharmacogenetic disorder of skeletal muscle.
- Masseter muscle rigidity (MMR) is a potential adverse reaction to succinylcholine, an anesthetic muscle relaxant.
- The association between MMR and MH susceptibility requires further investigation.
Purpose of the Study:
- To evaluate the incidence of MH susceptibility in patients experiencing MMR after succinylcholine administration.
- To identify clinical and biochemical markers associated with MH susceptibility in this patient cohort.
Main Methods:
- Seventy-seven patients with MMR post-succinylcholine underwent in vitro halothane and caffeine contracture testing for MH susceptibility.
- Serum creatine phosphokinase (CPK) levels were measured perioperatively.
- Patients were assessed for underlying myopathies.
Main Results:
- Thirty-nine of 77 patients (50.6%) were diagnosed as MH-susceptible.
- No demographic or surgical factors differentiated MH-susceptible from nonsusceptible patients.
- Perioperative CPK levels ≥ 20,000 IU within 24 hours of MMR (without myopathy) were observed in 6/30 MH-susceptible patients but none of the nonsusceptible patients.
Conclusions:
- MMR following succinylcholine administration is a presumptive sign of MH susceptibility.
- Elevated perioperative CPK levels (≥ 20,000 IU) are highly suggestive of MH susceptibility.
- Patients with MMR warrant evaluation for MH susceptibility and myopathies; succinylcholine should be avoided in subsequent anesthetics.