The Changing Face of Malignant Hyperthermia: Less Fulminant, More Insidious

Abstract

Modern anaesthetic techniques have resulted in the clinical presentation of malignant hyperthermia to be more often indolent and/or insidious than truly fulminant, as previously known in the anaesthetic community. We present four recently referred cases to illustrate this point: one late-onset case, two patients with slowly progressive hypercapnia as the sole sign and a fourth patient with postoperative myalgias and elevated creatine kinase. We also discuss the reasons for the shift in typical clinical presentation. The more insidious character of malignant hyperthermia is most likely due to the lower triggering potency of modern volatile anaesthetics, the mitigating effects of several intravenous drugs (neuromuscular blocking agents, alpha 2 adrenergic receptor agonists, beta-adrenergic blockade) or techniques (neuraxial anaesthesia) and the routine use of end-tidal CO 2 monitoring leading to the early withdrawal of triggering drugs. Awareness among anaesthetists of this change in presentation is important since the clinical diagnosis is often more doubtful and, if corroborative evidence is not sought, the diagnosis may be delayed or missed altogether.

Successful early application of extracorporeal membrane oxygenation to support cardiopulmonary resuscitation for a patient suffering from severe malignant hyperthermia and cardiac arrest: a case report

“…It is important that the prognosis of MH crisis depends on how soon MH is suspected and how rapidly an appropriate treatment is initiated; because the MH crisis including rigidity, muscle breakdown, cardiac involvement and metabolic derangement, is aggravated as time passes. However recently, the clinical manifestation of MH tended to have an insidious and delayed onset rather than a fulminant onset [4]. Therefore, the monitoring of raising ETCO 2 , an early sign of MH in the perioperative period, is important for early administration of dantrolene sodium.…”

“…Once MH is triggered, an abnormally high release of calcium from the sarcoplasmic reticulum is initiated, which results in a hypermetabolic state with signs such as hemodynamic instability, tachycardia, muscle rigidity, hypercapnia, hyperthermia, hypoxia, rhabdomyolysis and lactic acidosis [34]. …”

“…After the introduction of dantrolene sodium, a causative treatment became available [6], and the mortality rate for acute MH crisis decreased from approximately 70–80% to about 5% [7]. Also, due to the decreased use of succinylcholine and the increased use of modern volatile anesthetics (sevoflurane, desflurane), the face of MH is changing from fulminant to more insidious [4]. Nevertheless, MH can still be a life-threatening disease which causes cardiac arrest, especially since sudden cardiac arrest still has a low survival rate, despite the introduction of cardiopulmonary resuscitation (CPR) [8].…”

Movement Disorders in the Intensive Care Unit

“…25 Presentation is classically fulminant and acute, although more insidious forms have been reported. 28 Patients develop hyperthermia, autonomic instability, rigidity, and rhabdomyolysis as in NMS. 25 Unlike in NMS, metabolic acidosis and hypercapnia are more prominent, and transaminitis is less likely to occur.…”

Almost-certain malignant hyperthermia during cardiopulmonary bypass: a case report and literature review

“…4 However, the development of MH is changing from apparent to more insidious due to the decreased use of succinylcholine and the increased use of volatile anesthetics (sevoflurane and desflurane). 5 Even more specially, in the cardiac surgeries, the typical clinical signs and symptoms of MH would always be obscured by the non-physiological perfusion and hypothermia of cardiopulmonary bypass (CPB), potentially leading to a delayed diagnosis. 1,4,6 In addition, there are reports of postoperative MH after cardiac surgeries.…”