Forensic Considerations in Cases of Myotonic Dystrophy at Autopsy

Myotonic dystrophy (DM) is a chronic, slowly progressive, autosomal-dominant disorder with delayed muscle relaxation after contraction, distal skeletal muscle weakness, and atrophy. It has a reduced life expectancy due predominantly to respiratory failure or sudden cardiac death. The mortality rate is approximately 7.3 times greater than the general population with a mean age at death of 53 years. Degeneration of the cardiac conduction system causes atrioventricular block, arrhythmias, and ventricular failure. A case of sudden death in a 44-year-old woman with DM type 1 is reported to demonstrate an alternative lethal mechanism. At autopsy, there was extensive infiltration of skeletal muscles with adipose tissue. The heart was structurally normal. A deep venous thrombosis of the right calf was identified with a large saddle pulmonary thromboembolus and bilateral peripheral thromboemboli. DM1-related thrombosis had most likely occurred because of the decedent's impaired mobility, possible hypercoagulable state, and serum changes from muscle necrosis.