In this test a small piece of muscle is obtained under regional or general anesthesia and while still viable is placed in a special solution and attached to a device which measures the force of contraction. A response to Halothane or a response to low concentrations of caffeine are considered diagnostic for malignant hyperthermia susceptible muscle. All biopsies must be performed at the diagnostic center since the muscle must be fresh when tested. An abnormal response to the Halothane test and Caffeine test are shown below along with a technical description of the Halothane Caffeine contracture test. Let us now enter into the area of differential diagnosis, starting with the most common early symptoms of malignant hyperthermia.
Some biopsies are false positives.
Retake history - frequently can obtain new information on family or about muscle disease. Dantrolene is an antipyretic, response is not diagnostic, though it is more convincing if rapid and complete response occurs. Interpretation of CK increase may be more difficult since it may be blunted. State University, Hershey Penn. Episodes which start out like MH but turn out to be something else are important to identify so as to improve our diagnostic acumen.