Neurosurgery 1992-98 improvement. June 1994, Volume 34, Number 6 At our initial examination, abnormal findings were 1087 Windmill Pitcher's Radial Neuropathy isolated to the right radial nerve distribution. Strength Case Report in the right triceps was 4-/5, the brachioradialis and supinator were 0/5, and the wrist and finger extensors AUTHOR(S): Sinson, Grant, M.D.; 1/5. The left arm had normal strength throughout. The Zager, Eric L., M.D.; Kline, David G., M.D. right triceps and brachioradialis reflexes were absent. Sensation over the dorsal aspect of the patient's distal Division of Neurosurgery, Hospital of the University forearm and thumb was decreased. The remainder of of Pennsylvania (GS, ELZ), Philadelphia, the examination's findings were normal and Tinel's Pennsylvania; Department of Neurosurgery, sign did not occur over the brachial plexus or the Louisiana State University Medical Center (DGK), course of the radial nerve. A second EMG showed New Orleans, Louisiana fibrillations and positive sharp waves in the extensor Downloaded from https://academic.oup.com/neurosurgery/article/34/6/1087/2757659 by guest on 27 September 2021 digitorum and brachioradialis, with only occasional Neurosurgery 34; 1087-1089, 1994 fibrillations in the triceps. The deltoid was normal. A magnetic resonance imaging scan of the brachial ABSTRACT: THE AUTHORS PRESENT two cases plexus showed no mass lesion or anatomic anomaly. of severe radial nerve injury with different sites of Approximately 11 months after the injury, the right pathology but a similar mechanism: the "windmill" brachial plexus was explored via the infraclavicular pitching motion of competitive softball. Both patients approach. At operation, the posterior cord and radial required surgical intervention with neurolysis, and nerve were found to be severely scarred. A fusiform both improved postoperatively. The literature on neuroma in continuity measuring 16 cm in length and related radial nerve injuries is briefly reviewed and approximately three to four times the diameter of a pathophysiological mechanisms are discussed. normal posterior cord was found (Fig. 1). The axillary nerve was also involved, but not as severely. KEY WORDS: Athletic injuries; Brachial plexus; The lateral and medial cords as well as the axillary Nerve compression syndromes; Radial nerve injury; artery appeared normal. Radial nerve surgery Intraoperative electrophysiological recording was performed. A nerve action potential could not be The radial nerve is not infrequently injured during recorded from the posterior cord to the radial nerve, athletic or other strenuous activities. Midshaft and this was undoubtedly related to the severe fractures of the humerus and compression at the scarring. An extensive external and internal fibrous arcade of Frohse are commonly recognized neurolysis of the posterior cord and radial nerve was mechanisms of radial nerve injury. More recently, then completed under magnification. After cases of radial nerve entrapment by the fibrous arch neurolysis, stimulation of the posterior cord and at the lateral head of the triceps have been radial nerve did elicit triceps contraction. The documented (3-7,10). We present two cases of radial dissection was stopped at this point. nerve injury with different sites of pathology but a Initially after surgery, the patient had 1/5 triceps similar mechanism: the "windmill" pitching motion strength. By 21 months postoperatively, she has of competitive softball. recovered 4+/5 triceps function. She as yet has no distal function clinically, but there is now EMG CASE REPORTS evidence of reinnervation of the brachioradialis and Patient 1 extensor digitorum. This healthy 16-year-old, right-handed girl was referred to the Hospital of the University of Patient 2 Pennsylvania with a 10-month history of weakness in This 53-year-old, right-handed man came to the the right arm and hand. Her deficits were first noted Louisiana State University Medical Center with an 8- while she was learning the windmill pitching motion month history of progressive weakness in his right in her high-school softball team. The weakness in the arm. He had been a pitcher in a fast-pitch softball right arm was predated by 2 weeks of soreness in the league for many years. He did not recall any incident posterior aspect of her shoulder associated with of injury to the shoulder or arm, and there were no pitching. Her weakness then progressed over the complicating medical conditions. Physical course of the next month as she continued to pitch. examination revealed no tenderness or Tinel's sign She found that she could not release the ball at the along the course of the radial nerve. The right triceps end of the pitching motion. There was also transient was moderately weak (3/5), the brachioradialis weakness in the right shoulder. Neurological severely weak (1/5), and there was no contraction of examination and an electromyogram (EMG) the supinator, wrist, or finger extensors (0/5). The documented severe radial nerve palsy involving the triceps reflex was reduced and the brachioradialis triceps and all distal muscles innervated by the radial reflex absent. There were no sensory deficits. The left nerve. Apparently, her original deltoid weakness had arm had normal strength and reflexes throughout. The only been transient, since at the initial and all findings of the remainder of the examination were subsequent physical examinations she had normal normal. An EMG demonstrated partial denervation of deltoid strength. She was managed conservatively at the triceps and changes indicating severe denervation another institution for 10 months but experienced no in all distal muscles innervated by the radial nerve. Redistribution of this article permitted only in accordance with the publisher's copyright provisions. The radial nerve was surgically exposed on both branches to the triceps and proximal to the posterior the medial and lateral sides of the arm. An area of cutaneous branch. In dissecting the posterior thinning and discoloration was noted in the nerve just compartment of the arm, the radial nerve is found proximal to and within the region of the spiral groove coursing along the spiral groove of the posterior of the humerus. A nerve action potential was humerus and then deep to the lateral head of the transmitted across this narrow segment, but had a low triceps. These investigators found a fibrous arch of amplitude and conducted at only 32 m per second. As tendon giving rise to muscle fibers of the triceps in a result, a simple neurolysis was performed. "almost every case" (p 504). Indeed, in an unspecified After follow-up of 3.5 years, recovery has occurred number of dissections, some fibers originated below but has been incomplete. The triceps improved this arch and arose from the more distal humerus, significantly (4/5); the brachioradialis has 4/5 which they termed the "accessory origin of the lateral strength, the extensor carpi radialis 3/5, the extensor head" (p 503). The radial nerve courses between this carpi ulnaris 2/5, and finger extension 1/5. A tendon fibrous arch and the humerus and then, quite Downloaded from https://academic.oup.com/neurosurgery/article/34/6/1087/2757659 by guest on 27 September 2021 transfer to improve finger extension has been offered distinctly, through the opening in the lateral but was refused by the patient. He is able to continue intermuscular septum to enter the anterior his sales work satisfactorily but no longer plays compartment of the arm. Lotem et al. (3) also noted softball. that while there was no obvious compression of the radial nerve at this location, there was considerable DISCUSSION variability in how tight the fibrous arch was in These cases demonstrate two different sites of relation to the radial nerve (Fig. 2). radial nerve injury with the same unusual mechanism. Much earlier, Wilson (11) had speculated that some The windmill pitching technique used in fast-pitch patients may have an anatomic predisposition to softball places the shoulder through its full range of radial nerve injury. Lotem et al. (3) proposed motion. The initial movements fully abduct the compression by the fibrous arch of the lateral head of shoulder with the arm held above the head. As the the triceps as the source of this predisposition, arm is brought downward from behind, it undergoes particularly in muscular individuals. Since then, there rapid acceleration that results in forced elbow have been several descriptions of cases of radial extension and forearm supination along with shoulder nerve injuries occurring at the same portion of the rotation. How this complex motion can result in nerve but unrelated to previous muscular activity (4, isolated injury of the posterior cord and radial nerve 7). All of these injuries have been attributed to is not entirely clear. compression by the lateral head of the triceps. There are several reports of radial nerve injury due Operative exploration in these cases revealed either a to strenuous muscle activity (1,3-12). These have fibrous (4,7) or a muscular (5,6) arch of the lateral head similarities to our second patient. In 1892, Gowers of the triceps as the point of radial nerve compression (1) described three cases of radial nerve injury that (Fig. 2). Alternatively, Prochaska et al. (8) attributed occurred "... once during the act of pulling on a tight the nerve injury to an anomalous fibrous band from pair of boots, once from throwing a stone with the long head of the triceps. energy, and once from grasping a lamp-post to avoid A compressive mechanism alone cannot explain a fall during a severe attack of giddiness." Wilson the injury described in our first patient, however. (11) referred to radial nerve injury subsequent to Nerve traction can be related to arm traction, nerve sudden elbow extension, and Woltman et al. (12) diameter, and nerve length. Nerve traction varies described a radial nerve injury resulting from directly with arm traction (2).