Paraspinal and limb motor neuron involvement within homologous spinal segments in ALS.
ABSTRACT We studied the involvement of motor neuron groups innervating paraspinal muscles in amyotrophic lateral sclerosis (ALS) and evaluated the value of paraspinal muscle EMG in the diagnosis of the disease.
We used quantitative concentric needle EMG to study denervation and reinnervation in a paraspinal muscle and a limb muscle innervated by the C6 and L5 segments in 32 patients with ALS. As control subjects we studied 11 patients with peripheral neuropathy, and 46 non-neurogenic control subjects.
We found similar abnormalities in motor-unit potentials (MUPs) in paraspinal and limb muscles in these two segments in ALS. Fasciculation potentials (FPs) were more frequent in limb muscles than in paraspinal muscles and fibrillations and sharp waves (fibs-sw) were most frequent in tibialis anterior. In peripheral neuropathy paraspinal muscles were normal but tibialis anterior showed very abnormal motor unit potentials.
These results are consistent with generalised involvement of motor neurons in motor neuron pools in spinal segments in early stages of ALS progression. However, distally predominant fibrillations indicate susceptibility to ongoing denervation in reinnervated distal axons. Complex FPs of similar morphology to MUP analysis in the same early affected muscle suggests a proximal origin for these FPs at this phase.
Our observations emphasize the value of paraspinal muscle EMG in the electrophysiological diagnosis of ALS.
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ABSTRACT: A method for quantifing shape variability, the jiggle, of motor unit potentials (MUPs) recorded with conventional EMG electrodes is presented. Amplitude variability at each point of time of the MUP was analyzed. Two new parameters are proposed: the normalized value of the consecutive amplitude differences (CAD), and the crosscorrelational coefficient of the consecutive discharges (CCC). Simulations showed that increased jitter of the constituent single fiber potentials increases the jiggle as expressed by an increase in CAD and decrease in CCC values. Even when the jitter value of each component was fixed, increased temporal dispersion increased the jiggle whereas an increased number of fibers decreased the jiggle. This new method has been applied in normal subjects, patients with chronic neurogenic diseases and patients with ALS. Jiggle was significantly increased in the ALS group, in agreement with visual observations. We believe that this method for quantifying jiggle will increase the information obtainable from routine EMG investigations. © 1994 John Wiley & Sons, Inc.Muscle & Nerve 09/1994; 17(10):1135 - 1144. · 2.31 Impact Factor
Article: Amyotrophic Lateral Sclerosis