Comparison of the Nerve Conduction Parameters in Proximally and Distally Located Muscles Innervated by the Bundles of Median and Ulnar Nerves

Abstract

Objective: The aim of this study was to investigate and compare the conduction parameters of nerve bundles of median and ulnar nerves that innervate proximal and distal muscles. Subjects and Methods: Thirty male and 30 female healthy volunteers between 18 and 70 years of age were enrolled in the study. The conduction parameters were recorded from the proximally located flexor carpi ulnaris, pronator teres and the flexor carpi radialis muscles to the distally located abductor digiti minimi and abductor pollicis brevis muscles for the ulnar and median nerves. Each nerve was stimulated at the region above the elbow and at the axillary region separately. The Student t test was used for statistical analysis, and Levene's test was used to assess whether or not the group variances exhibited a uniform distribution. Results: The conduction velocities were faster (78.27 ± 6.55 vs. 67.83 ± 6.76 m/s, and 74.57 ± 5.66 and 74.23 ± 5.88 vs. 66.38 ± 6.85 m/s) and the durations of compound muscle action potential (CMAP) response were longer (15.65 ± 2.43 vs. 13.55 ± 1.78 ms, and 16.38 ± 2.39 and 16.04 ± 2.34 vs. 13.40 ± 1.79 ms) in proximally located muscles than in distally located muscles that are innervated either by ulnar or median nerves (p < 0.001). However, the CMAP amplitudes were smaller (2.52 ± 1.16 vs. 5.81 ± 3.13 mV, and 2.90 ± 1.20 and 3.59 ± 1.66 vs. 6.88 ± 2.77 mV) in proximal muscles than in distal muscles (p < 0.001). There was no significant difference (p > 0.05) between males and females regarding conduction velocities and CMAP amplitudes recorded from proximal and distal muscles. Conclusion: Proximal muscles innervated by median or ulnar nerves had lower CMAP amplitude values, longer CMAP durations and higher conduction velocities than distal muscles. These findings could reveal a temporal dispersion and phase cancellation due to desynchronized conduction during nerve stimulation.

Üst Ve Alt Ekstremi̇tede Ayni Si̇ni̇r Tarafindan İnerve Olan Proksi̇mal Ve Di̇stal Kaslardan Kaydedi̇len F Dalgasi: Yeni̇ Bi̇r Yöntem Olabi̇li̇r Mi̇?

“…When the minimum latencies of the F-wave recorded from the distal and proximal muscles in the lower and upper extremities were compared, it was found that the minimum latencies of the Fwave recorded from the proximal muscles (FUP and FPP) were longer than the minimum F-wave latencies recorded from the distal muscles (FUD and FPD). In previous studies comparing nerve conduction velocities, conduction velocity was found to be higher in proximal muscles with greater mass then the distal small muscles even they are innervated by the same nerve [6,12,13]. Considering the physiology of the Fwave, it is conceivable that the F-wave latency recorded from the proximal muscle should be shorter.…”

“…This may be due to the distance of the recording electrodes from the muscle due to the excess of subcutaneous tissues in the proximal large mass muscles. One reason for this difference may be that the proximal relatively large mass muscles have higher desynchronization and temporal dispersions, which contain muscle fibers of different nerve conduction diameters [12,14,15]. Previous F-wave studies found that F-wave minimum latency increased with age by 0.03 ms/year in the upper extremity and 0.1 ms/year in the lower extremity.…”

Diagnostic Value of Median Nerve Conduction Velocity Across Wrist Among Patients With Suspected Carpal Tunnel Syndrome

“…Recent studies have documented that the diameter of the peripheral motor nerve gradually decreases until it reaches the target muscle. (16) The mentioned reference value might be inaccurate in the distal segment.…”

Use of collision tests to identify physiological differences between the median and ulnar nerves

“…Some reports describing previous studies stressed that conduction velocities could change along the nerve . Therefore, we analyzed CVD using distal stimulus at the wrist and proximal stimulus at the level of the elbow (conduction along the forearm) in both nerves so that we could eliminate the influence of the conduction velocity slowing within the carpal and Guyon tunnels as well as changes in conduction velocity because of different levels of stimulations.…”