Neurophysiological changes in muscles and nerves in COPD

Abstract

Muscle atrophy, fiber-type shifting, reduced contractility, metabolic alterations, capillarization defect, and mitochondrial modifications are important adaptations in COPD. Skelatal muscle dysfunction is one of the most devastating systemic manifestations of COPD which eventually leads to increase in morbidity and mortality. In this study we aimed to demonstrate the effects of COPD on both muscles and nerves in neurologically normal patients with different degrees of airflow limitations, using current electrophysiological methods.Electrophysiological examinations were performed using a Keypoint EMG machine with subjects lying supine on a bed at a room temperature. Tests were nerve conduction studies, motor unit potential (MUP) analysis, interference pattern (IP) analysis and macro EMG (mEMG) analysis on the right side in the upper and lower extremities. Multi-motor unit potential (m-MUP) analysis and interference pattern (IP) analysis revealed some changes in biceps brachii (BB) and tibialis anterior (TA) muscles, but macro EMG (mEMG) analysis was similar except for increased fiber density at TA muscles in COPD patients. Increased ulnar and sural sensory latency, decreased ulnar sensory velocity, and increased ulnar motor latency values were found in COPD. There was increased motor unit potential (MUP) turn and phase values in BB muscles and increased MUP turn and decreased MUP duration, area, area/amplitude ratio and size index values in TA muscles in COPD patients. As a conclusion, in COPD more nerve conduction abnormalities and more MUP abnormalities which reflected muscle fiber diameter changes were observed by the use of electrophysiological methods including multi MUP - IP analysis and mEMG analysis.