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LETTER TO THE EDITOR

Could This Be Malignant Hyperthermia?

University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh; Pittsburgh, Pennsylvania; lbroadman{at}aol.com

In Response:

As described in our case report, metabolic alkalosis, carbon dioxide retention, volume depletion, and tachycardia as a consequence of the patient's prematurity and ongoing medical management were all present prior to the start of the anesthetic, and probably all of these factors, along with the rhabdomyolysis, contributed to the patient's elevated temperature in the postoperative period.1–4 Issues involving the diagnosis of classic malignant hyperthermia due to ryanodine receptor type 15,6 abnormality, and the possible benefits of dantrolene7,8 administration in patients with or without a pathologic muscular diagnosis, were also initially included, but one of the reviewers felt this discussion was unnecessary since this was not a case of malignant hyperthermia (M.H.).

Dantrolene treatment may be a useful agent to dissipate heat,9 even in the absence of pathology. Although we agree that cautious administration of dantrolene might have helped to rescue this infant from postoperative hyperthermia and might have decreased the rhabdomyolysis, both the primary anesthesiologist and the MH Hotline Consultant, who retrospectively reviewed this case, did not believe this patient had classic MH. All of the patient's symptoms could be explained by his underlying, coexisting metabolic issues and underlying muscle disorder.

Although the Caffeine Halothane Contracture Test (CHCT) is the gold standard for diagnosing MH, certain caveats about MH testing are important: (1) Muscles from patients with myopathies do not contract normally. (2) In patients with myopathies, it is difficult to define both negative and positive CHCT and consequently correctly interpret the results from myopathic patients. Therefore, many MH Diagnostic Center Directors will not perform CHCT for patients with known myopathies. (3) Blood tests can be used to screen for known MH causative mutations in the ryanodine receptor. However, genetic testing of MH susceptibility has relatively low sensitivity when the patient does not have a first-degree relative with a well-characterized MH causative mutation. Thus, the value of testing this infant for MH was thought to be minimal. Because the distinction between Duchenne Muscular Dystrophy and classic MH susceptibility has great implications for future management of the health of family members,10 we emphasize the need for a pathologic diagnosis. Only with a pathological diagnosis can the patient and family be referred to an appropriate neurologist for follow-up and genetic counseling.

It is important to recognize that MH and Duchenne Muscular Dystrophy are separate entities. Patients with either disorder can suffer similar complications in the perioperative period (i.e., hyperkalemia and rhabdomyolysis), and in the past, patients with Duchenne Muscular Dystrophy were frequently thought to have MH.

Although the debate regarding the ideal anesthetic for patients known to have some type of myopathy will no doubt continue, we believe that prior knowledge of the disease, rather than the anesthetic drugs administered, is most important to the safe outcome of the anesthetic.11 In our opinion, withholding inhalational anesthetics in patients with Duchenne Muscular Dystrophy because of concerns about MH is not necessary.

REFERENCES

1. Phadke A, Broadman LM, Brandom BW, Ozolek J, Davis PJ. Postoperative hyperthermia, rhabdomyolysis, critical temperature and death in a former premature infant after his ninth general anesthetic. Anesth Analg 105:977–80
2. Bouchama A, Knochel JP. Heat stroke. N Engl J Med 2002;346:1978–88[Free Full Text]
3. Leung WK, Jahr JS, Hotz J, Pollock M. Nonmalignant hyperthermia on induction of anesthesia in a pediatric patient undergoing bidirectional Glenn procedure. J Clin Anesth 1999;10:427–31[Web of Science]
4. Soler R, Echegaray M, Rivera MA. Thermal responses and body fluid balance of competitive male swimmers during a training session. J Strength Cond Res 2002;17:362–7[Web of Science]
5. Robinson RL, Anetseder MJ, Brancadoro V, van Broekhoven C, Carsana A, Censier K, Fortunato G, Girard T, Heytens L, Hopkins PM, Jurkat-Rott K, Klinger W, Kozak-Ribbens G, Krivosic R, Monnier N, Nivoche Y, Olthoff D, Rueffert H, Sorrentino V, Tegazzin V, Mueller CR. Recent advances in the diagnosis of malignant hyperthermia susceptibility: How confident can we be of genetic testing? Eur J Human Genetica 2003;11:342–8
6. Sambuughin N, Holley H, Muldoon S, Brandom BW, de Bantel AM, Tobin JR, Nelson TE, Goldfarb LG. Screening of the entire ryanodine receptor type 1 coding region for sequence variants associated with malignant hyperthermia susceptibility in the North American population. Anesthesiology 2005;102:515–21[Web of Science][Medline]
7. Zhao X, Weisleder N, Han X, Pan Z, Parness J, Brotto M, Ma J. Azumolene inhibits a component of store-operated calcium entry coupled to the skeletal muscle ryanodine receptor. J Biol Chem 2006;281:33477–86[Abstract/Free Full Text]
8. Gailly P. New aspects of calcium signaling in skeletal muscle cells: implications in Duchenne muscular dystrophy. Biochim Biophys Acta 2002;1600:38–44[Medline]
9. Gerbershagen MU, Becker S, Burmester S, Starosse A, Wappler F. Comparison of the therapeutic effectiveness of dantrolene and ryanodex in porcine malignant hyperthermia. Available at: www.asaabstracts.com. Last accessed November 7, 2007. A1922, Presented October 17, 2007
10. Shukry M, Guruli ZV, Ramadhyani U. Suspected malignant hyperthermia in a child with laminin 2 (merosin) deficiency in the absence of a triggering agent. Ped Anesth 2006;16:462–5
11. Breucking E, Reimnitz P, Schara U, Mortier. Severe anaesthetic incidents in patients and families with Duchenne and Becker type muscular dystrophy. Der Anaesthetist 2000;49:187–95

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