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 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 , Hospital of the University 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 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 with different sites of Approximately 11 months after the injury, the right 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 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 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 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 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 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). The windmill pitcher throwing a discus. Lotem et al. (3) added three cases of achieves ball velocities of 40 to 70 mph. A 6.5-ounce transient radial nerve palsy, all occurring after ball moving at 50 mph, generates a centrifugal force strenuous activity (one patient had been doing arm that would be equal to the linear force generated by extension exercises, another was pushing a heavy holding a 250-pound weight [force = mass × container, and the third had been loading a truck). (velocity)2/radius]. The rarity of this type of injury Mitsunaga and Nakano (6) reported an additional attests to the effectiveness of the shoulder's support patient who sought treatment after an 18-hour period structures (muscles, tendons, ligaments, and shoulder of muscular overexertion (heavy lifting). The patient capsule) in limiting traction transmitted to the in Manske's (5) report recalled wrestling with stronger brachial plexus (10). opponents on several occasions preceding the onset Nerve traction varies inversely with nerve of symptoms. Weiss and Idler (10) treated a patient diameter. The posterior cord and radial nerve are not with radial nerve injury from traction. The woman unique in this regard when compared with adjacent had slipped and grabbed the rung of a ladder to nerves in the brachial plexus. It is striking that the prevent herself from falling. Prochaska et al. (8) lateral and medial cords, which lie within 1 to 2 cm of reported the case of a man with the sudden onset of a the posterior cord, were completely spared in our first radial nerve deficit after practicing his tennis serve. patient. The anatomical basis of this observation may Finally, Streib (9) recently presented three cases that be that nerve tension is also inversely proportional to occurred after many hours of heavy manual labor. the length of the nerve. When the medial and lateral To explore this mechanism further, Lotem et al. (3) cords leave the axillary region under the pectoralis performed cadaver dissections of the radial nerve. minor, they travel into the anterior soft tissue Clinically and electrophysiologically, the lesions that compartment as the median and ulnar nerves. There they had presented were localized to the area distal to are no points at this level where these nerves are Redistribution of this article permitted only in accordance with the publisher's copyright provisions. known to be tethered. In contrast, the posterior cord 1892, p 85. leaves the axillary region and then courses around the 2. Klein AH, France JC, Mutschler TA, Fu FH: humerus as the radial nerve. It passes through the Measurement of brachial plexus strain in fibrous or muscular arch of the lateral head of the arthroscopy of the shoulder. Arthroscopy triceps, the lateral intermuscular septum, and then the 3:45-52, 1987. arcade of Frohse. If any of these structures acted to 3. Lotem M, Fried A, Levy M, Solzi P, Najenson tether the radial nerve, its functional length used to T, Nathan H: Radial palsy following muscular dissipate tension would be shortened, thus making it effort. J Bone Joint Surg [Br] 53:500-506, more susceptible to a stretch injury. 1971. The clinical outcomes of the patients described in 4. Lubahn JD, Lister GD: Familial radial nerve the literature have been quite variable. All three entrapment syndrome: A case report and patients in the report by Lotem et al. (3) improved literature review. J Hand Surg [Am] 8:297-

with conservative : two recovered fully and 299, 1983. Downloaded from https://academic.oup.com/neurosurgery/article/34/6/1087/2757659 by guest on 27 September 2021 the third had minimal residual deficits but was able to 5. Manske PR: Compression of the radial nerve return to work. Lubahn and Lister (4) explored the by the triceps muscle. J Bone Joint Surg radial nerve after 3 months of conservative therapy [Am] 59:835-836, 1977. resulted in no improvement. By 6 months 6. Mitsunaga MM, Nakano K: High radial nerve postoperatively, their patient had only slight residual palsy following strenuous muscular activity. weakness. Prochaska et al. (8) explored and Clin Orthop 234:39-42, 1988. decompressed the radial nerve 6 months after injury 7. Nakamichi K, Tachibana S: Radial nerve and noted no improvement after 2 years of follow-up. entrapment by the lateral head of the triceps. J Three additional patients were operated on and Hand Surg [Am] 16:748-750, 1991. showed no improvement (5-7), although the follow-up 8. Prochaska V, Crosby LA, Murphy RP: High periods were short (4-6 mo). The earliest operation in radial nerve palsy in a tennis player. Orthop this latter group was performed 11 months after the Rev 22:90-92, 1993. onset of symptoms. Finally, the case of pure traction 9. Streib E: Upper arm radial nerve palsy after injury improved with an end-to-end epineural repair muscular effort: Report of three cases. performed 10 months after injury (10). 42:1632-1634, 1992. In conclusion, we have presented two cases of 10. Weiss APC, Idler RS: Radial nerve rupture severe radial nerve injury precipitated by the after a traction injury: A case report. J Hand "windmill" arm motion of softball pitchers. This may Surg [Am] 17:69-70, 1992. represent the tremendous traction force of this motion 11. Wilson SAK: Neurology. Baltimore, Williams in combination with the predisposition of the radial & Wilkins, 1940, pp 323-328. nerve to be tethered distally. An additional anatomic 12. Woltman HW, Kernohan JW, Goldstein NP: risk factor may be present in patients with a narrow Diseases of peripheral nerves, in Baker AB fibrous arch at the lateral head of the triceps. Such (ed): Clinical Neurology. London, Hoeber- injuries require surgical exploration when Harper, 1965, pp 1816-1848. conservative management fails to result in clinical or EMG signs of recovery. Surgical intervention may result in gratifying recovery in selected cases. Since neurolysis rather than repair was the procedure COMMENTS indicated by the operative findings in both of these This interesting report demonstrates two cases of cases, the value of neurolysis itself is uncertain. radial nerve injury associated with the pitching Nonetheless, exploration and intraoperative motion of competitive softball. In one case, the recordings did help to elucidate the findings that pathological lesion was in the distal posterior cord, appeared to be responsible for this unusual clinical and in the other, the lesion was near the spiral groove picture. of the humerus. Both patients were benefitted by exploration with neurolysis. ACKNOWLEDGMENT The radial nerve can be entrapped or undergo The authors would like to acknowledge Doreen traction injury at multiple sites along its course. Most Shikitino for her assistance with the preparation of frequently, the site of entrapment is at the arcade of this manuscript and for her art work. Frohse or at the midhumeral shaft beneath the lateral head of the triceps muscle. can be Received, August 10, 1993. helpful in localizing the traction or entrapment injury. Accepted, December 14, 1993. Denervation in the forearm extensors with sparing of Reprint requests: Eric L. Zager, M.D., Division of the brachioradialis places the lesion at the arcade of Neurosurgery, Hospital of the University of Frohse. Denervation of the brachioradialis with Pennsylvania, 3400 Spruce Street, Philadelphia, PA sparing of the triceps means a lesion near the spiral 19104-4283. groove of the humeral shaft; denervation of the triceps with sparing of the deltoid puts the lesion in REFERENCES: (1-12) the proximal radial nerve in the axilla; and denervation of the deltoid will suggest a lesion in the 1. Gowers WR: A Manual of Diseases of the posterior cord. Nervous System. London, J and A Churchill, It is important to explore patients with radial nerve Redistribution of this article permitted only in accordance with the publisher's copyright provisions. dysfunction if the dysfunction does not improve over several months, as it usually does in a simple Saturday night palsy. The use of intraoperative conduction techniques is mandatory for making intraoperative decisions regarding neurolysis versus resection and grafting. In the patient who does not regain full function of finger, wrist, and thumb extensors, tendon transfer is often beneficial.

Suzie C. Tindall Atlanta, Georgia

This study is important in its stressing that radial Downloaded from https://academic.oup.com/neurosurgery/article/34/6/1087/2757659 by guest on 27 September 2021 nerve injuries may result from muscular efforts with the arm. We have observed a similar case wherein a major-league pitcher developed an abrupt onset of radial nerve palsy 4 hours after pitching. The patient felt an unusual electric feeling in his arm after throwing an overhand fast ball, after which he was taken out of the game. All muscles innervated by the radial nerve and its branches distal to the triceps were affected. Spontaneous recovery was first evident 3 months after injury. The patient simply was followed up and went on to a full recovery. He continued to pitch once recovered, but only lasted in the major leagues for a short time. The common mechanism for these injuries appears to be stretching of the arm during extreme muscular effort. How should these injuries be managed? As in our case, spontaneous recovery is possible. If repetition of extreme muscular effort is anticipated upon recovery, however, serious consideration should be given to exploration and decompression, as was done in one of the cases reported here. Division of the fibrous band formed by a tendinous portion of the long head of the triceps may prevent reinjury and relieve ongoing entrapment.

James N. Campbell Baltimore, Maryland

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Figure 1. Patient 1. Intraoperative photograph Downloaded from https://academic.oup.com/neurosurgery/article/34/6/1087/2757659 by guest on 27 September 2021 showing the massive neuroma in continuity (arrows) involving the radial nerve and, to a lesser extent, the posterior cord and axillary nerve. The lateral and medial cords and axillary artery are normal.

Figure 2. Schematic diagram of the radial nerve passing under the fibrous arch of the lateral head of the triceps. Redistribution of this article permitted only in accordance with the publisher's copyright provisions.