Masseter contracture and tachycardia causing termination of anesthesia.

A careful preoperative history can be helpful in detecting problems with previous anesthetic experiences. However, it has been found that in the patients who have developed a complete syndrome of malignant hyperthermia (MH), 30% had prior uneventful general anesthesia. It is therefore of extreme importance when delivering anesthesia to recognize the signs of MH early in order to initiate correct procedures to prevent the development of a fulminating crisis of MH.