The succeeding slides present conditions that are associated with MH, possibly related to MH, and could mimic MH.

The muscular dystrophies are a group of diseases characterized by progressive but variable rate of loss of muscle function. Duchenne’s muscular dystrophy is the most severe form. It is a inherited as a recessive trait that is expressed in boys (x-linked). The abnormality is due to lack of production of dystrophin. Dystrophin deficiency weakens the muscle cell membrane increasing susceptibility to cell membrane damage. Serum creatine kinase levels reflect the progression of skeletal muscle degeneration (17).

Becker’s dystrophy’s clinical presentation resembles that of Duchene’s dystrophy. However, its onset is delayed and the progression of the disease is slower. Patients with Becker’s dystrophy have abnormal dystrophin or reduced levels of normal dystrophin (17).

Myotonia dystrophica is the most common form of a group of diseases known as the myotonias. The basic clinical feature is delayed relaxation of the skeletal muscle after voluntary contraction. It is an autosomal dominant inherited disorder (17).

As mentioned earlier, patients with these diseases may not develop signs of skeletal muscle weakness until adolescence. Exposure to some anesthetics, however, may “unmask” the disease. Succinylcholine is contraindicated in patients with dystrophinopathy because massive rhabdomyolysis, hyperkalemia, and cardiac arrest can occur. Also, prolonged exposure to inhalation anesthetics, without exposure to succinylcholine, may be followed by severe rhabdomyolysis. To confirm the diagnosis of any form of dystrophinopathy, muscle, even post-mortem muscle can be assayed for dystrophin. Or any genetic material can be examined for the characteristic defect on the X chromosome.