Myotonias and army personnel: symptoms and effects on service fitness.

Myotonias are rare disorders characterized by difficulties in skeletal muscle relaxation. Either dominant or recessive modes of inheritance are possible. Underlying gene mutations cause defects in the ion channels of the muscle membranes. Previously undiagnosed myotonias may occur among military conscripts. We report here eight such patients with enhanced symptoms of myotonia during their military service. Six patients had myotonia congenita, one had myotonic dystrophy, and one paramyotonia congenita. In myotonia congenita, serum creatine kinase and aldolase levels correlated with the recommended service fitness classification. Because some anesthetic agents may have unfavorable side effects in myotonia, both patients and anesthesiologists need to be aware of the diagnosis. The awareness of military surgeons regarding the possibility of myotonia is necessary to provide a correct diagnosis and to establish the service fitness of these patients.