Recorded by Albert C. Clarimont, MD

Made with monopolar needle from various muscles and different persons. Please view the waveform and then consider the comments and discussion.

Fibrillation potentials. These are spontaneous muscle fiber depolarizations seen in a variety of conditions which result in loss of normal inhibition. These conditions include denervation, inflammation of muscle, dystrophic myopathy, and even flacidity of upper motor neuron origin. Each fibrillation represents the depolarization of a single muscle fiber, and recurs in a regularly repeating pattern. They are of short duration, from 0.5 to 1.5 msec, and varied amplitude of 20 to 1000 microvolts. Watch video

Complex repetitive discharge (CRD). These high frequency patterns are produced in states of chronic muscle membrane denervation or injury. Their pathological significance is the same as that of sharp positive waves, and both represent unstable muscle membranes. The CRD is noted for starting and ending abruptly. Watch video

Myopathy. Small amplitude, short duration motor unit potentials (MUP) are seen. As is typical, the recruitment pattern shows early activation of many MUPs at low strength. Watch video

Myotonic discharges. These musical patterns are seen in myotonic diseases including both the dystrophic and non-dystrophic types. They wax and wane both in amplitude and frequency. Watch video

End Plate Spikes. These potentials occur normally in association with the end-plate zone of the muscle. They are single muscle fiber related, and therefore short in duration (0.5 to 1.5 msec). In contrast to fibrillation potentials, the end-plate spikes repeat in an irregular pattern. Often the patient reports greater discomfort during the recording of these potentials. Watch video

Fasiculation Potentials. These spontaneous potentials represent activation of motor unit potentials (MUP) at the neuron or axon level. Fasiculations occur slowly and irregularly, at a frequency of less than one per second. They can occur with any neuropathic process, but are most frequently reported in association with anterior horn cell (motor neuron) diseases. This association is thought related to the occurrence of reinnervation by sprouting of axons, resulting in MUPs which are large in amplitude and therefore easily detected. A few fasiculations can be seen in the muscles of healthy persons, and are typically more likely to be seen in the presence of caffeine. Non-pathologic fasiculations usually recur at a very slow rate (less than 3 per 10 seconds), while pathologic fasiculations most commonly occur more frequently than 3/10sec. When the motor unit includes enough muscle fibers, a clinical fasiculation can be observed with muscle movement under the skin. Watch video