CLINICAL-APPLICATION OF A NONINVASIVE MULTIELECTRODE ARRAY EMG FOR THE RECORDING OF SINGLE MOTOR UNIT-ACTIVITY

Using a recently developed noninvasive EMG recording technique with mu lti-electrode arrays we investigated the pattern and distribution of m otor unit action potentials (MUAP) following maximal voluntary contrac tion of the musculus abductor pollicis brevis. An additional parameter , i. e. muscular conduction velocity (CV) in single motor units, was c alculated from the multi-electrode array EMG recordings. From 63 healt hy children of various age the normal EMG pattern and CV were derived and compared to the EMG of diagnosed patients known to suffer from Duc henne muscular dystrophy and from spinal muscular atrophy. In normal i ndividuals the muscular CV in neonates was lowest at 1-2 m/s and gradu ally reached a plateau of 2.9-4 m/s from the age of 4 years onwards. T he EMG in 31 children with Duchenne muscular dystrophy showed an abnor mal pattern with low amplitude action potentials. In 30 out of 31 pati ents a significantly lower muscular CV was found. In 10 children with spinal muscular atrophy the EMG showed action potentials of abnormally large amplitude and a reduced recruitment of firing motor units. The muscular CV remained within the normal range.Compared to classical nee dle EMG the application of this new noninvasive EMG technique in child ren is painless and offers an easy-to-handle diagnostic tool to differ entiate between neuromuscular diseases of denervating or of myopathic origin.