Neuromuscular transmission abnormalities in myotonic dystrophy type 1: A neurophysiological study

• We report neurophysiological abnormalities in DM1, suggesting a NMJ impairment.
• This impairment could contribute to weakness and fatigue in DM1 patients.
• Our results, if further confirmed, could support the use of anticholinesterase drugs.

ObjectivesWeakness and fatigue are frequent symptoms in myotonic dystrophy type 1 (DM1), mainly as a result of muscle impairment. However, neuromuscular junction (NMJ) abnormalities could play an additional role in determining these manifestations. We aimed to document the possible NMJ involvement in DM1.Patients and methodsIn order to substantiate this hypothesis we performed low rate repetitive nerve stimulation (RNS) and single fiber electromyography (SFEMG), in 14 DM1 subjects.ResultsRNS resulted abnormal in four patients while SFEMG revealed a pathological jitter in ten. A significative correlation was found between jitter values and decrementing response (p < 0.000311; r = 0.822).ConclusionThese results suggest a possible involvement of NMJ in DM1.