Concentric needle EMG versus macro EMG I. Relation in healthy subjects.
OBJECTIVE
The relation between motor unit action potentials (MUAPs) recorded via a macro needle electrode (MA-MUAP, MA-EMG) and MUAPs recorded via a concentric needle electrode (CN-MUAP, CN-EMG) is under debate. In particular it is not known to what degree CN-MUAP variables reflect the electrical properties of a motor unit.


METHODS
CN-EMGs and MA-EMGs of the right brachial biceps muscle were recorded from 40 healthy subjects (23 women and 17 men) aged 17-83 years and CN-MUAP and MA-MUAP variables were cross-correlated.


RESULTS
CN-MUAP duration was positively and significantly correlated with CN-MUAP area (r=0.52), rate of polyphasia (r=0.45), MA-MUAP amplitude (r=0.47) and MA-MUAP area (r=0.45). CN-MUAP amplitude was positively and significantly correlated with the rate of polyphasia (r=0.39) and the fibre density (r=0.45).


CONCLUSIONS
CN-MUAP duration appropriately reflects the motor unit's electrical activity and may substitute MA-MUAP area and amplitude.
Finsterer
J
J
Ludwig Boltzmann Institute for Research in Epilepsy and Neuromuscular Disorders, Vienna, Austria. fij@2nr.nkr.magwien.gv.at
Fuglsang-Frederiksen
A
A
D000200:Action Potentials / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002452:Cell Count; D004567:Electrodes, Implanted; D004576:Electromyography / Q000295:instrumentation* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D015203:Reproducibility of Results; D012737:Sex Factors; D018709:Statistics, Nonparametric