TY - JOUR
T1 - Postpolio Muscular Atrophy
T2 - Diagnostic Utility of Macroelectromyography
AU - Lange, Dale J.
AU - Smith, Torben
AU - Lovelace, Robert E.
PY - 1989/5
Y1 - 1989/5
N2 - Muscles recovered from previous poliomyelitis may exhibit new weakness and wasting years after the original infection (postpolio muscular atrophy). Routine electrophysiological and morphological techniques may not differentiate weakening muscles from previously affected but stable muscles. We used quantitative motor unit potential analysis, single-fiber electromyography, and macroelectromyography (macro-EMG) to determine if these techniques could identify weakening muscles. We classified 18 previously affected muscles according to strength from 12 patients who had had poliomyelitis 18 to 50 years earlier. Muscles of normal strength had large-amplitude macro-EMG signals (1000 to 4110 μV; normal level, <390 μV). Muscles with new weakness and atrophy had smaller than expected macro-EMG amplitude (130 to 450 μV). Two muscles with weakness and atrophy unchanged since the original childhood infection had markedly increased macro-EMG amplitude (1710 and 1860 μV), suggesting the increased macro-EMG amplitude is due to stable reinnervation not strength. Mean motor unit potential duration and amplitude were lower in newly weakened muscles, but jitter, fiber density, and blocking were similar in all muscles regardless of strength. We conclude that low-amplitude macro-EMG signals may be useful in the identification of muscles weakened by postpolio muscular atrophy.
AB - Muscles recovered from previous poliomyelitis may exhibit new weakness and wasting years after the original infection (postpolio muscular atrophy). Routine electrophysiological and morphological techniques may not differentiate weakening muscles from previously affected but stable muscles. We used quantitative motor unit potential analysis, single-fiber electromyography, and macroelectromyography (macro-EMG) to determine if these techniques could identify weakening muscles. We classified 18 previously affected muscles according to strength from 12 patients who had had poliomyelitis 18 to 50 years earlier. Muscles of normal strength had large-amplitude macro-EMG signals (1000 to 4110 μV; normal level, <390 μV). Muscles with new weakness and atrophy had smaller than expected macro-EMG amplitude (130 to 450 μV). Two muscles with weakness and atrophy unchanged since the original childhood infection had markedly increased macro-EMG amplitude (1710 and 1860 μV), suggesting the increased macro-EMG amplitude is due to stable reinnervation not strength. Mean motor unit potential duration and amplitude were lower in newly weakened muscles, but jitter, fiber density, and blocking were similar in all muscles regardless of strength. We conclude that low-amplitude macro-EMG signals may be useful in the identification of muscles weakened by postpolio muscular atrophy.
UR - http://www.scopus.com/inward/record.url?scp=0024605625&partnerID=8YFLogxK
U2 - 10.1001/archneur.1989.00520410036019
DO - 10.1001/archneur.1989.00520410036019
M3 - Article
C2 - 2712746
AN - SCOPUS:0024605625
SN - 0003-9942
VL - 46
SP - 502
EP - 506
JO - Archives of Neurology
JF - Archives of Neurology
IS - 5
ER -