Diaphragmatic Central Motor Conduction Changes In Chronic Obstructive Pulmonary Disease

Background and objectives Respiratory muscles dysfunction has been reported in COPD. Transcranial magnetic stimulation (TMS) is easy non-invasive that has been used for assessing the respiratory corticospinal pathways particularly of diaphragm. We aimed to study the cortico-diaphragmatic motor system changes in COPD using TMS and to correlate the findings with the pulmonary function. Methods A case control study recruited 30 stable COPD from the out-patient respiratory clinic of Main Alexandria University hospital-Egypt and 17 healthy control subjects who were subjected to spirometry. Cortical conduction of the diaphragm was performed by TMS to all participants followed by cervical magnetic stimulation of the phrenic nerve roots. Diaphragmatic resting motor threshold (DRMT), cortical motor evoked potential latency (CMEPL), CMEP amplitude (CMEPA), peripheral motor evoked potential latency (PMEPL), PMEP amplitude (PMEPA) and central motor conduction time (CMCT) were measured. Results 66.7% of COPD patients had severe and very severe COPD with median age of 59 (55-63) years. There was statistically significant bilateral decrease in DRMT, CMEPA and PMEPA in COPD group versus healthy subjects and significant increase in CMEPL and PMEPL ( p <0.01). Left CMCT was significantly prolonged in COPD group versus healthy subjects ( p <0.0001) but not right CMCT. Further, there was significant increase in CMEPL and CMCT of left versus right diaphragm in COPD group ( p = 0.003 and 0.001 respectively) that inversely correlated with FEV 1 % and FVC% predicted. Conclusion Central cortico-diaphragmatic motor system is affected in COPD patients with heterogeneity of both sides that is correlated with pulmonary function. Significance Coticospinal pathway affection could be a factor for development of diaphragmatic dysfunction in COPD patients accordingly its evaluation could help in personalization of COPD management especially pulmonary rehabilitation programs