[Satellite potentials: definition, normal values and validity in the detection of mild myogenic lesions]

From the right m. biceps brachii and the right m. rectus femoris of 28 healthy women aged 19 to 30 years and 16 possible and obligate Duchenne-carriers aged 26 to 40 years we recorded 20 motor unit action potentials each. A satellite potential was defined as electrical activity following or preceding the main component and separated from it by an isoelectrical interval of at least 1, 2 or 3 ms. The most appropriate of these 3 satellite potential definitions is the one that proceeds from a 1 ms minimum interval, because it allows the detection of more satellite potentials than the two others. Applying this definition (minimum interval between the main component and the satellite potential 1 ms) to our controls data we computed a mean interval duration of 5 (m. biceps brachii) respectively 3.4 ms (m. rectus femoris), a mean satellite potential duration of 4.4 (m. biceps brachii) respectively 3.7 ms (m. rectus femoris) and a mean satellite rate of either 3.9 (m. biceps brachii) or 1.6% (m. rectus femoris). We observed up to 3 motor unit action potentials with a satellite potential and up to 1 polyphasic motor unit action potential with a satellite potential per 20 motor unit action potentials. There was little difference between the controls and the Duchenne-carriers satellite parameter means. Only the m. rectus femoris satellite potential duration was increased in Duchenne-carriers.(ABSTRACT TRUNCATED AT 250 WORDS)