Typical features include an unusual facies often described as “Noonan-oid" with low-set
ears, hypertelorism, downslanting palpebral fissures, ptosis, strabismus, a high-arched
palate or cleft palate, micrognathia, crowded teeth, and short, webbed neck. Orthopedic
findings include short stature, thoracic kyphosis, lumbar hyperlordosis, pectus carinatum,
frequent dislocations of shoulders and patellae, and pes cavus. Cryptorchidism and mental
delay are other frequent findings. There is one case report about a patient with
dilatation of the aorta, pulmonary artery, and the cardiac ventricles. Malignant
hyperthermia presents as a hypermetabolic response of the skeletal muscles to triggering
agents, namely, inhalational anesthetic agents and succinylcholine. Combined metabolic and
respiratory acidosis, tachycardia, hypertension, hypoxia, muscle rigidity, and
myoglobinuria occur as a result of sustained muscle contraction. Hyperthermia is often a
late sign in the course of malignant hyperthermia. Not all exposures will trigger a
malignant hyperthermia response: approximately half of the patients who are susceptible to
malignant hyperthermia had uneventful general anesthetics with triggering agents prior to
the triggering event (in some patients more than 10 uneventful non-trigger-free
anesthetics have been administered).