P219 Cortical excitability in Dystrophia Myotonica type 1

Abstract

Objectives Dystrophia Myotonica type 1 (DM1) is characterized by distal muscle weakness, atrophy, myotonia and CNS involvement. Electrophysiological assessment of CNS involvement in DM1 patient refers to multimodal evoked potential studies. Herein we investigated the function of central motor pathways in DM1 patients by transcranial magnetic stimulation (TMS) and the possible relationships with disease duration, muscular impairment and MRI findings. Methods Eight right-handed DM1 patients and 10 healthy adult volunteers (control group) were included in the study. Fazekas scale was used to quantify the amount of white matter lesion (WMLs) in MRI performed to all DM1 patients. TMS test battery consisted of AMT, RMT, central conduction time (CCT), cortical silent period (SP), and paired-pulse TMS paradigm. Results Mean age and disease durations of patients’ were 37.2 and 7.02 years, respectively. WMLs were found in 62.5% of the patients. There were no significant differences between DM1 and control group in terms of AMT, RMT and SP (p ⩽ 0.05). DM1 cases showed statistically significant lower long interval intracortical inhibitions (LICI) as compared to the control group. Discussion The number of cortical excitability studies in neuromuscular and especially DM1 patients is limited. In this study, lower LICI in DM1 patients suggests that cortical excitability in these patients is less inhibited. Also, WML incidence in DM1 patients was found relatively high. The nature, significance and relationship of these findings can be investigated further by different cohorts and TMS protocols. Conclusion TMS might help demonstrate the nature of CNS involvements. Significance Cortical excitability changes in DM1.