Electrodiagnostic localization of traumatic upper trunk brachial plexopathy.

Eighteen patients having traumatic upper trunk brachial plexopathy ("the stinger"), a common football injury, were investigated electrodiagnostically. Proximal nerve conduction was determined by stimulating the supraclavicular fossa and at the C5 root and recording from muscles supplied by the long thoracic, suprascapular, musculocutaneous, axillary, lateral pectoral and thoracodorsal nerves. The accessory nerve was stimulated in the lateral posterior triangle and the evoked potential recorded from the upper trapezius muscle. Median and ulnar nerves were also tested, sensory and motor fibers being stimulated peripherally and proximally. Conduction slowing was observed in 16 patients mainly in the proximal segments of the axillary, musculocutaneous, suprascapular and accessory nerves. The most commonly observed electromyographic abnormalities were an increase in polyphasic waves and decreased recruitment. Spontaneous activity was sparse. These abnormalities appear to result most likely from compression of the most superficially located fibers of the brachial plexus at Erb's point. As a significant etiologic factor, the impact of ill-fitting shoulder pads against the neck during a football tackle is suggested. This empirical observation was supported by the decrease of "stingers" after the improvement of the shoulder gear.