Biomedical Engineering Reference
In-Depth Information
logical process is related to the degeneration of the motoneuron; in myogenic ones
the degeneration begins from the muscle fibers. In neurogenic processes some mus-
cle fibers lose their innervation due to motoneuron death and are reinnervated by the
surviving motoneurons; in effect the amplitude and duration of MUAP increases and
the number of MUAPs in the pick-up area of electrode decreases. During the phase
of acute reinnervation newly formed endplates are unstable and generate increased
jitter. In myogenic disorders the amplitude and duration of MUAPs is reduced; they
become polyphasic and contain satellite potentials. The typical examples of normal,
neurogenic, and myogenic potentials are shown in Figure 4.50. More information
about physiological and pathological processes in muscles and their influence on
MUAP shapes may be found in [Buchthal, 1985].
FIGURE 4.50: Examples of single MUAPs recorded during weak muscle contrac-
tions from normal and diseased muscles: a) control , b) Duchenne muscle dystrophy
(myogenic disease), c) amyotrophic lateral sclerosis (neurogenic disease). For each
type three 30-ms epochs from different subjects are shown, with a few single MUAPs
marked by distinct numerals. Calibration bars: horizontal, 5 ms; vertical: 200 μ Vfor
a) and c), 100 μ V for b). Note complex MUAPs in b) and c), indicated by broken line
boxes. (By courtesy of M. Piotrkiewicz.)
 
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