Concentric-needle versus macro EMG. II. Detection of neuromuscular disorders.
OBJECTIVE
Little is known about the relation and sensitivity of macro-EMG (MA-EMG) compared with concentric-needle EMG (CN-EMG) in the detection of neuromuscular disorders.


METHODS
CN-EMGs and MA-EMGs were recorded from the right brachial biceps muscle of 40 healthy subjects, aged 17-83 years, 20 patients with neurogenic disorders, aged 25-75 years, and 20 patients with myopathy, aged 18-76 years. Motor unit action potentials (MUAPs) were examined.


RESULTS
In patients with neurogenic disorders CN-MUAP duration, CN-MUAP amplitude, percent polyphasia, MA-MUAP amplitude, MA-MUAP area and fibre density were significantly increased. In patients with myopathy, only fibre density was significantly increased. In patients with neurogenic disorders, the sensitivity of CN-EMG was 80%, and that of MA-EMG 85%. In myopathies, the sensitivity was 50% for each technique. Pooling the results of both EMG techniques, the sensitivity increased to 90% in patients with neurogenic disorders, and to 65% in myogenic disease.


CONCLUSIONS
MA-EMG has a similar sensitivity in the detection of neuromuscular disorders as CN-EMG. Particularly when myopathy is suspected, both techniques should be applied if one is unrevealing.
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; D000368:Aged; D004576:Electromyography / Q000379:methods*; D005260:Female; D006008:Glycogen Storage Disease / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017240:Mitochondrial Myopathies / Q000503:physiopathology; D016472:Motor Neuron Disease / Q000503:physiopathology; D009046:Motor Neurons / Q000502:physiology; D009134:Muscular Atrophy, Spinal / Q000503:physiopathology; D009468:Neuromuscular Diseases / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology*; D011115:Polyneuropathies / Q000503:physiopathology; D012016:Reference Values; D012044:Regression Analysis; D013595:Syringomyelia / Q000503:physiopathology