Sphincter electromyography in diagnosis of multiple system atrophy: technical issues.
Possible technical reasons for the controversy over the role of sphincter electromyography (EMG) in the diagnosis of multiple system atrophy (MSA) were analyzed. In a review of the literature, a high sensitivity (>60%) was found reported in 11 studies that included late components, and no value of the test was found in 4 studies that excluded them. This was also corroborated in a pilot study of 5 patients with probable MSA. With late components included, the mean motor unit potential (MUP) duration was prolonged in all 4 patients with an adequate single-MUP analysis sample and, with late components excluded, in 2 of 5 patients on multi-MUP analysis. At least in diagnostic EMG of MSA patients, late components should be included in the measurement of MUP duration.
Podnar
Simon
S
Institute of Clinical Neurophysiology, University Medical Center Ljubljana, SI-1525 Ljubljana, Slovenia. simon.podnar@kclj.si
Fowler
Clare J
CJ
D000200:Action Potentials / Q000502:physiology; D000368:Aged; D001003:Anal Canal / Q000503:physiopathology*; D003937:Diagnosis, Differential; D003951:Diagnostic Errors / Q000517:prevention & control*; D004576:Electromyography / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000175:diagnosis* / Q000503:physiopathology; D009119:Muscle Contraction / Q000502:physiology; D010300:Parkinson Disease / Q000175:diagnosis / Q000503:physiopathology; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results