Reinnervation of dystrophic muscles

Objective - To analyse the regenerating capability of the peripheral nerve fibers and the capability of the muscle fibers to accept the regenerating a nd new nerve sprouts in myotonic dystrophy (MD). Material and methods - One male, aged 58 years, diagnosed of MD at the age or 30 years, suffered neur algic amyotrophy in the right shoulder girdle 4 weeks before admission. Nee dle EMG and nerve conduction studies were performed on admission and 6, 12, and 18 months later. Results - Oil admission there were atrophy and absenc e of voluntary contraction in deltoids, supra- and infraspinatus muscles. E MG showed abundant fibrillations, positive sharp waves and myotonic bursts in these Muscles without voluntary activity, consistent with axonal neuropa thy of both axillary and suprascapular nerves. The follow-up showed signs o f reinnervation 6 months later and slight loss of long duration and high am plitude MUPs at 18 months of evolution, with good clinical recovery. This i s compatible with chronic neurogenic atrophy, presumably as ail expression of type grouping. Conclusions - The reinnervation capability of the nerve f ibers and the capability of muscle fibers membrane to accept regenerating a nd new nerve sprout remain in MD. Myotonic bursts persist after total dener vation.