This is an example of normal needle insertional activity. Note the electrical activity associated with needle insertion and electrical silence associated with cessation of needle movement. This is an example of normal needle insertional activity associated with needle movement. In this example of miniature end plate potential recording, note the initial baseline irregularity. As I withdraw the needle away from the end plate, the baseline quiets down. Reinsertion of the needle close to the end plate again produces the miniature end plate potential activity. A needle electrode is purposely inserted into an end plate region. Note the prototypical end plate spike morphology of an initial negative onset and negative spike followed by a terminal positive phase. Also, note the highly irregular firing rate of this particular end plate spike. When a needle electrode is inserted into the end plate zone, in addition to observing prototypical biphasic initially negative end plate spikes, it is also possible to observe triphasic end plate spikes as well as end plate spikes that appear to have a morphology similar to a so-called positive sharp wave. This is an example of multiply different end plate spikes with different morphologies, prototypical as well as atypical appearing end plate spikes. Again, note the In addition to the prototypical appearing end plate spikes, a needle electrode located in the end plate region may occasionally record what appear to be irregularly discharging motor unit action potentials preceded by what also appears to be an end plate spike. In this example of normal recruitment, we note that the patient begins firing a single motor unit at roughly 10 hertz. As the patient increases the muscular force production, the firing rate of the motor unit also increases. This continues until such a force level is reached that the patient recruits a second motor unit. We note that the firing rate of the first motor unit when the second motor unit is recruited in this case is approximately An example of decreased insertional activity is depicted. Note the reduction in the electrical activity associated with needle insertion. This is quite unlike normal insertional activity. An example of increased insertional activity is demonstrated. Note the initial insertion of the electrode and the persistence of electrical activity following cessation of needle movement. In this case, we see what appears to be a series of positive sharp waves following the needle is depicted. Note the regular inter-spike interval that is quite characteristic of positive sharp waves and in this case, fibrillation potentials. A prototypical positive sharp wave is shown. Note the regular firing rate of this particular potential with the exception of a slight slowing of its firing rate just before it ceases to discharge. This is an example of a combination of positive sharp waves and fibrillation potentials. Positive sharp waves, initial positive deflection, small terminal negative spike, as well as fibrillation potentials. A recording of complex repetitive discharges is depicted. Note how the complex regularly repeats itself with the same set of potentials within each particular complex. An example of a complex repetitive discharge is demonstrated. Note the repetitive firing of the complex as well as the consistency of the set of discharges within each complex. Also, you'll note that this particular complex repetitive discharge ceases to fire abruptly, which is characteristic of complex repetitive discharges. A typical myotonic discharge is demonstrated. Note the waxing and waning characteristic of these potentials. A series of myotonic discharges are depicted. Note the waxing and waning characteristics of these myotonic discharges. A number of fasciculation potentials are shown. Note the irregular discharge rate of these potentials. A series of myokymic discharges are shown. Note the burst of electrical activity of irregularly firing motor units within a burst and the area of silence between the different bursts. A recording from the paraspinal muscles of a patient with stiff man syndrome demonstrates A patient with Isaac syndrome is depicted with a recording from the vastus medialis demonstrating the myokymic-like discharges, possibly consisting of multiplets. A series of motor unit action potentials comprising a cramp as recorded from the abductor A cramp discharge as recorded from a patient with familial cramp syndrome is shown. A series of doublet potentials are shown. Note how the second potential is slightly smaller in amplitude than the first because it fires in the relative refractory period of the first discharge. An example of doublets as well as multiplets is shown in this recording. Here we have a good example of a multiplet. A typical Parkinsonian tremor is noted. Observe the bursts of electrical activity with the associated silence in between each burst. A series of nascent or early motor unit action potentials are recorded in a patient with newly reinnervated muscle fibers. Note the depiction of two satellite potentials associated with a motor unit action potential. The first satellite potential is stable, whereas the second satellite potential appears to jitter back and forth, implying that it is unstable. A normal motor unit action potential is shown. Note that it is stable with respect to each discharge. It does not vary in amplitude. A single motor unit action potential recorded from a patient with Lambert-Eaton syndrome demonstrates the motor unit action potential amplitude variability from one discharge to A needle recording from a patient with ALS demonstrates reduced recruitment, and we see here a single motor unit action potential firing at roughly 40 hertz. A recording from a patient with polymyositis demonstrates a few motor unit action potentials initiated with minimal voluntary contraction. However, as the patient just increases their force production, a whole host of motor units come into play and essentially obliterate the baseline. A typical example of 60 hertz interference is shown. The introduction of a 60 hertz notch filter can eliminate this interference. However, ensure that it does not also interfere with the potentials you are recording. A typical EKG artifact can be recognized if the sweep speed is slowed and the regularity of the discharge observed. A pacemaker artifact can be recognized by the regularity of its discharge.

electromyography

EMG

muscle activity

needle electrodes

pathological potentials

EMG patterns

diagnostic interference

EMG

electromyography