EMG ACTIVITY OF UPPER LIMB MUSCLES IN THE CASE OF NERVOUS MUSCULAR TRANSMISSION’S PATHOLOGY IN THE HUMAN

Abstract

In many cases of a disease or an injury of the upper extremity nerve impulses are impaired. The high level of diagnostic and tactical errors in upper limb's nerve damage often leads to poor treatment outcomes. An important, and sometimes decisive, factor in the choice of treatment is the assessment of the functional state of the nerves and muscles of the affected limb segment. The purpose of this testing is to study the features of the upper limb muscles's EMG activity in normal and in the case of clinical pathology of neuromuscular transmission. 24 volunteers between the ages of 17 and 32, both male and female, with the right profile of manual asymmetry took part in the study. While dividing into groups, the presence of the diagnosted pathology of the upper right limb's neuromuscular transmission was taken into account. Accordingly, we created a "pathological" (n = 8) and "healthy" (n = 16) groups. In both groups, we sequentially recorded the M-response of the abductor pollicis brevis during stimulation of the nerve medianus as well as the M-response of the abductor digiti minimi during stimulation of the nerve ulnaris. The M-response amplitude, residual latency (RL), and excitation propagation rate (EPR) were analyzed. It has been established that the amplitudes of the M-responce during EMG stimulation of the abductor pollicis brevis and the abductor digiti minimi were lower in pathological group than tin normal. According to our results, RL of examined muscles' M-response increased with distanting away from the stimulation point (muscle's working point). In the case of pathology we observed longer RL of M-responce than in healthy testees. In the case of stimulation of the abductor pollicis brevis EPR was comparely higher on the elbow-shoulder segment and the wrist-shoulder segment in the pathological group, wereas while stimulation of the abductor digiti minimi we established inverse relationship. EPR in all segments, namely the wrist-shoulder and elbow-shoulder, was lower in the pathologic group compared to the norm.