O-36 Listening the sound of neuromuscular junction during voluntary contraction

Abstract

Background Sound is an indispensable component of electromyography. Although neurophysiologists are familiar with the end-plate noise and spikes, it is preferred to measure the neuromuscular transmission during voluntary contraction in time domain that is expressed in microseconds (jitter). Present study is aimed to create an audible voice of jitter and enable the physician to notice the difference between a healthy and a diseased neuromuscular transmission by hearing. Material and methods During voluntary contraction of frontalis muscle, single-fiber-like action potential pairs were recorded by using smallest concentric needle with 1 kHz high-pass filtering. Traces harboring potential pairs acquired from healthy participants and myasthenia patients were transferred. Signals were de-noised, locations of the two highest peak’s amplitude and the difference between them were determined. The average of these differences was calculated (jitter). “The sound of jitter” can be composed from the difference values of the locations of two highest peak’s amplitude. These values are duplicated in same amount proportionally up to 48,000 samples for achieving a 5 s length of sound. Then, they were sampled with 8 kHz. “The sound of jitter” was heard by using a function in “Matlab”. Results Sound of a healthy junction is soft; but in patients, it’s louder and contains more high frequency components. Conclusions Increased jitter reflects high variability of neuromuscular transmission. Converting it to an audible sound serves a different perspective. By doing so, the only irregularity that is heard would be the failure in junction transmission rather than the irregular firing of motor unit.