To the Editor:-We have read with great interest the report by Maeda et al. [1]describing a case of malignant hyperthermia during sevoflurane anesthesia followed by a muscle weakness persisting for almost 3 months after the event. However, a few questions regarding the diagnosis and management of what was thought to be an episode of malignant hyperthermia remain to be answered.

The signs and symptoms described are strongly suggestive of malignant hyperthermia, however, for reasons of better comparison we would have appreciated the use of the clinical grading scale for malignant hyperthermia. [2]According to the data given, we calculated a score exceeding 50 points. Thus, the probability of malignant hyperthermia would have to be considered as almost certain.

Second, the dose of dantrole (100 mg in a patient weighing 80 kg) seems to be rather low, which requires more detailed explanation. Unfortunately no data are given as to the postoperative concentration of creatine phosphokinase. As no muscle biopsy was performed, what was the evidence of muscle destruction in this patient? Why was no in vitro contracture test performed to test the susceptibility for malignant hyperthermia? Despite the high score in the clinical grading scale, the in vitro contracture test would have been the only means to confirm the diagnosis of malignant hyperthermia. [3] 

Andrea Michalek-Sauberer, M.D.

Hermann Gilly, Ph.D.

Department of Anesthesiology and General Intensive Care; University of Vienna, AKH Wien; Waehringer Guertel 18–20; A-1090 Vienna; Austria

(Accepted for publication December 10, 1997.)

Maeda H, Iranami H, Hatano Y: Delayed recovery from muscle weakness due to malignant hyperthermia during sevoflurane anesthesia. Anesthesiology 1997; 87:425-6.
Larach MG, Lacalio AR, Allen GC, Denborough MA, Ellis FR, Gronert GA, Kaplan RF, Muldoon SM, Nelson TE, Ording H, Rosenberg H, Waud BE, Wedel DJ: A clinical grading scale to predict malignant hyperthermia susceptibility. Anesthesiology 1994; 80:771-9.
Ording H, Brancadoro V, Cozzolino S, Ellis FR, Glauber V, Gonano EF, Halsall PJ, Hartung E, Heffron JJA, Heytens L, Kozak-Ribbens G, Kress H, Krivosic-Horber R, Lehmann-Horn F, Mortier W, Nivoche Y, Ranklev-Twetman E, Sigurdsson S, Snoeck M, Stieglitz P, Tegazzin V, Urwyler A, Wappler F: In vitro contracture test for diagnosis of malignant hyperthermia following the protocol of the European MH Group: Results of testing patients surviving fulminant MH and unrelated low-risk subjects. Acta Anaesthesiol Scand 1997; 41:955-66.