[Early electromyographic signs in congenital myotonic dystrophy. A study of ten cases]

Ten cases of congenital myotonic dystrophy have been reported and EMG findings described. In 5 neonates, EMG was performed between the 4th and 27th d of life. Four very severe cases had a fatal outcome, the 6 others were of mild severity, showed hypotonia, motor delay and mental handicap. In 9 cases, diagnosis was not established before birth. The EMG myogenic criteria were present in 2 muscles or more in each case, and were predominantly present in the proximal muscles. Clinical myotonia was absent in all cases but electrical myotonia was provoked by motor nerve stimulation using a current of long duration. The authors emphasize the interest of this stimulation-detection method which was able to exhibit myotonic discharge in 6 patients including 3 neonates.