Modifica di Clinic Electromyography (sezione)

====MUP Parameters====
The following parameters are used in clinical diagnostics: duration, amplitude, size index, spike duration, area, number of phases, number of turns, number of satellites, jiggle.
**Duration**: Includes the main spike, including the initial and terminal parts. The duration reflects the number of muscle fibers in the motor unit and the diameter of the examined fibers.
**Spike duration**: Measured between the first and last positive peak of the MUP. It reflects the temporal dispersion of the potentials of muscle fibers adjacent to the electrode.<ref name="Stalberg2" />
**Amplitude**: Measured between the highest positive and negative peaks. It reflects the number of muscle fibers in the motor unit, their diameter, and distribution.<ref name="Sacco">Sacco G., Buchtal F.: Motor unit potentials at different ages. Arch Neurol 6:366-373, 1962.</ref>
**Spike area**: Calculated by integrating the rectified MUP over the amplitude and spike duration.
**Thickness**: The area divided by the amplitude, which is closely related to the duration but less influenced by baseline variations.
**Number of phases**: The number of crossings of the baseline (isoelectric line). In normal motor units, 2-3 phases are present. MUPs with more than 5 phases are considered polyphasic.
**Number of turns**: The number of positive and negative peaks with an amplitude of no less than 50 µV.
The number of phases and turns reflects the temporal distribution of the action potential volley within the motor unit.
**Size index**: is a new parameter. It represents the thickness normalized for amplitude. It is increased in neurogenic conditions and decreased in myogenic conditions.

**Satellite potentials**: represent reinnervation situations. They are more easily recognized using manual methods, often showing jitter, resulting in reduced amplitude after averaging.<ref name="McGill1">Mc Gill K.C., Cummins K.L. et al.: Automatic decomposition of the Clinical Electromyography. IEE Trans Biomed Engin 32:470-77, 1985.</ref>

**Variability of MUP, “jiggle”**: In normal muscles, consecutive MUPs obtained from a motor unit are morphologically stable. In the early stages of collateral reinnervation, the jitter and intermittent conduction blocks of single fiber action potentials manifest as instability of the terminal portion of the MUP with variations in the potential shape, known as "jiggle".<ref name="McGill2">Mc Gill KC, Dorfman LJ: Automatic EMG decomposition in brachial biceps. Electroencephalogr Clin Neurophysiol 61:561-67,1988.</ref> A method has been developed to measure the jiggle by determining the median of consecutive amplitude differences (CAD) for each MUP point within a predetermined analysis window.