Elbow Wrist Syndrome
Last reviewed: 23.04.2024
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The ulnar syndrome of the wrist (defeat in the canal of Guyon) is characterized by paresthesia on the inner surface of the hand, sometimes with irradiation on the forearm, with hypodesa only on the palmar surface of the V finger. The weakness of the flexion and reduction of the V finger is revealed, and the finger I is reduced.
Diagnostic value is provoked by painful tests (finger compression, effleurage, cuff).
Electrophysiological methods of research are of special diagnostic value. Stimulation of the ulnar nerve can be performed transdermally, using surface electrodes or injected into the muscle needle. To investigate the motor latent period and the rate of impulse conduction along the ulnar nerve, the electrodes are superposed or inserted into the region of the muscle that removes the little finger.
The surface active recording electrode can be superimposed on the middle of the tenar. This arrangement of the electrode allows one to withdraw muscle potentials when stimulating not only the ulnar but also the median nerve.
In order to investigate the conduct of the pulse along the ulnar nerve at all possible levels of its compression, it is necessary to irritate the nerve at four points: in the axillary region, above the elbow, below the elbow and at the wrist. This technique allows us to investigate four motor latent periods and three velocities of carrying out pulses along the ulnar nerve.
Because of the different location of the points in which the ulnar nerve is irritated, the average values of the speed of impulses in certain segments of the nerve in groups of healthy individuals vary considerably. Thus, the velocity of the elbow nerve on the shoulder fibers is 65.7 - 53.6 m / s, and in the perlateral segment of the nerve 57 - 44 m / s. Almost always there is a significant decrease in the rate of impulses in the perlateral segment of the nerve compared to the speed of the shoulder and forearm. If this research is performed with the full extension of the elbow joint, the average speed in the perolatete segment (49.9 m / s) is 20.2% lower than on the forearm. If the average speed is determined when the upper limb is bent at the elbow at an angle of 70 °, it rises in the periblate nerve segment to 62.7 m / s, comparing with the speed on the forearm.
The distal motor latent period is normally in the area of the "wrist - muscle that removes the little finger", on average, from 2.3 to (3.38 ± 0.005) m / s. This figure in the "wrist - muscle leading to the thumb" area is 2.8 m / s average, and at the distance "above the elbow joint - the muscle that removes the little finger" - (7.9 ± 0.85) m / from. When the nerve is stimulated above the elbow joint and the muscular potential is withdrawn from the ulnar flexor of the wrist (with an average distance of 13.5 cm between the stimulating and withdrawing electrodes), the motor latent period is (3.1 ± 0.3) m / s.
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