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Clinical Anesthesiology, 4e
| Section IV. Physiology, Pathophysiology, & Anesthetic Management > |
Case Discussion: Masseter Spasm & Malignant Hyperthermia
Sections: Case
Discussion: Masseter Spasm & Malignant Hyperthermia, What
Is Malignant Hyperthermia?, What
Is the Pathophysiology of MH?, How
Should an Episode of MH Be Treated?, Describe
the Mechanism of Action of Dantrolene, Its Recommended Dosage, and
Its Possible Side Effects., What
Is the Differential Diagnosis of Masseter Spasm during Intubation?, Which
Patients Should Be Considered at Increased Risk for Developing MH?, What
Type of Hereditary Pattern Does MH Follow?, How
Is Susceptibility to MH Confirmed?, How
Does MH Differ from Neuroleptic Malignant Syndrome?, What
Other Diseases Can Present Like MH?, What
Constitutes a Safe Anesthetic in Patients Who Are Susceptible to
MH?.
Topics Discussed: anesthesia, pediatric; dantrolene sodium; malignant hyperthermia due to anesthesia; masseter muscle.
Excerpt:
"A 4-year-old boy is scheduled for correction of strabismus. Inhalational
induction with nitrous oxide and halothane is followed by the intravenous
administration of atropine and succinylcholine. Rigidity of the
masseter muscle prevents mouth opening and intubation.Malignant hyperthermia (MH) is a rare (1:15,000 in pediatric
patients and 1:40,000 adult patients) myopathy, characterized by
an acute hypermetabolic state within muscle tissue following induction
of general anesthesia. It can also present in the postoperative
period more than an hour after anesthesia and even without exposure
to known triggering agents, albeit rarely. Although most cases are
reported in pediatric patients, all ages can be affected. The earliest
signs reported during anesthesia are masseter muscle rigidity (MMR),
tachycardia, and hypercarbia due to increased CO2 production
(Table 44–7). Two or more of these
signs greatly increase the likelihood of MH. Tachypnea is prominent when
muscle relaxants are not used. Sympathetic system overactivity produces
tachycardia, arrhythmias, hypertension, and mottled cyanosis. Hyperthermia
may be a late sign, but when it occurs, core temperature can rise
as much as 1°C every..."
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