[The electroneuromyographic study of the radial nerve: compressive ischemic neuropathy of the posterior interosseous nerve]

Abstract

The electroneuromyographic study of the posterior interosseous nerve (PIN) with determination of conduction block (CB) at the level of the upper third of the forearm using the surface electrodes has been carried out. Seven healthy volunteers, 22 patients with compressive-ischemic neuropathy (CIN) at the level of the supinator, 14 patients with the total affection of the radical nerve, aged from 21 to 64 years, have been studied. The M-response has been recorded from the extensor digitorum communis. Stimulation has been performed at: (1) the middle of the forearm; (2) the lateral brachium; (3) the axillary crease; (4) the Erb's point; (5) the sulcus of ulnar nerve; (6) the cubital flexion; (7) the inner part of the shoulder. A method of stepwise stimulation has been used in the segment "a middle third of the forearm--a middle third of the shoulder". The M-responses of similar shape and amplitude have been recorded by stimulation of the first and second points in the controls. The M-responses recorded by stimulation of the brachial plexus were higher by average of 44,2% compared to the radical nerve in the shoulder area. The focal CB was found between two stimulation points in 86,4% of patients with PIN CIN that was confirmed by the method of stepwise nerve stimulation as well. The correlation between CB and the data of the global electromyogram was revealed. In patients with the total affection of the radical nerve, the M-responses during stimulation of distal and proximal PIN points were absent and the similar M-responses were recorded by stimulation of the brachial plexus (the Erb's point and the axillary crease) as well as the inner part of the shoulder.