The Association of Malignant Hyperthermia and Unusual Disease: When You’re Hot You’re Hot, or Maybe Not

Abstract

Barbara W. Brandom, MD This issue of Anesthesia & Analgesia brings together a collection of papers focused on the prevalence of malignant hyperthermia (MH), the possible association of exertional heat illness with MH, and the association of myotonias, muscular dystrophies, core myopathies, and enzymopathies with MH. Although these papers have a global perspective, a number of them originate from a 1-day symposium held during the 2008 Society for Pediatric Anesthesia Spring meeting in San Diego. The purpose of this symposium was to discuss the relationship of these disorders to MH in light of what is currently understood with regard to their molecular basis and to identify the clinical challenges that these disorders present to pediatric anesthesiologists. Because a number of case reports and small series have described patients with these disorders and clinical symptoms of increased temperature, arrhythmias, rhabdomyolysis, and/or hyperkalemia during or after anesthesia, the clinician is confronted with the question of whether there is a true association between these disorders and MH. In view of the relative rarity of these disorders, establishing an association between these disorders and MH becomes difficult. One of the many challenges of providing anesthesia for pediatric patients is that rare or unusual diseases often remain undiagnosed in infancy and early childhood because they have not produced sufficient physiological impairment or clinical signs and symptoms to merit evaluation. This is especially true in pediatric patients with underlying neuromuscular disorders or enzymopathies undergoing anesthesia for muscle biopsies. In addition, critical incidents during anesthesia occur more frequently in infants and small children compared with older children and adults. Airway and cardiovascular instability frequently occurs on induction of anesthesia in infants and small children. Induction of anesthesia by inhalation of potent anesthetic is a method that can facilitate airway management. To further complicate the anesthetic management, IV access is often a challenge in pediatric patients. The need for venous access can become a major determinant of anesthetic technique. Usually the pediatric patient who presents for a muscle biopsy has only a tentative diagnosis and therefore the risk of MH in this patient is unknown. Part of the dilemma in assessing MH risk in these patients is understanding the limitations in the MH literature and numerous case reports describing adverse anesthetic events. The “gold standard” for confirming a diagnosis of MH has been the in vitro contracture test. The sensitivity and specificity of the caffeine halothane contracture test has been determined in patients who did not have clinical myopathy. The sensitivity of a diagnostic test is the probability of that test being positive when the patient has the disease. Specificity of the test is the probability of a negative or normal test result when the patient does not have the disease. Any diagnostic test with high sensitivity has a low false negative rate, and tests with a low specificity have a high incidence of false positives. The From the *Department of Anesthesiology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine; and †University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania. Accepted for publication June 19, 2009. Barbara W. Brandom has received research funding from the Malignant Hyperthermia Association of the United States (MHAUS). The North American MH Registry (which is financially supported by MHAUS) may be affected financially by this publication. MHAUS is a not-for-profit organization focused on MH. Peter J. Davis is a consultant for EISAI Pharmaceuticals, Abbott Laboratories, and Hospira. Address correspondence and reprint requests to Peter J. Davis, MD, Department of Anesthesiology, Children’s Hospital of Pittsburgh, 45th and Penn, Pittsburgh, PA 15201. Address e-mail to davispj@anes.upmc.edu. Copyright © 2009 International Anesthesia Research Society DOI: 10.1213/ane.0b013e3181b493d4