Tennis elbow and radial tunnel syndrome: Differential diagnosis and treatment
DANIEL L. MORRISON, DD. Garden City, Michigan
This localizing pain syndrome, without a sensory Radial tunnel syndrome can deficit, often can be reproduced with resisted ex- masquerade as resistant tennis elbow. tension of the wrist. Pain at the lateral aspect of the It is a peripheral entrapment elbow can be produced also by resisted dorsal eleva- neuropathy similar to carpal tunnel tion of the middle finger with the elbow extended syndrome and is characterized by (Fig. 1). This "middle finger test" usually is reliable localized pain in the proximal volar and indicates that at least a portion of the extensor portion of the forearm, a positive wad is involved in a pain-producing process. middle finger test, and exacerbation of pain with resisted supination of the Mechanism of pain forearm. The condition usually The extensor carpi radialis brevis, which inserts at responds satisfactorily to the base of the middle finger, is tensed about the conservative measures, but surgical lateral epicondylar ridge and indeed may represent release of the entrapment sometimes is a major factor in the genesis of pain, that is, ten- indicated. This procedure brought dinitis, about the elbow. Both the radial tunnel immediate improvement in six cases, syndrome and tennis elbow usually produce a posi- with return to work without tive middle finger test, but there is an important restrictions in a short period. distinction in the specific locale of pain, both indi- rect and direct. Tennis elbow will be manifested usually at the lateral epicondylar tip but radial tunnel syndrome will produce pain at the proximal volar radial part of the forearm, approximately 2 fingerbreadths distal to the flexor crease of the elbow and just medial to the extensor wad (Fig. 2). Peripheral entrapment neuropathy of the posterior The difference in pain site will persist with direct interosseous nerve in the proximal part of the pressure and with the middle finger test. Another forearm, sometimes referred to as "radial tunnel major difference in the clinical presentation of the syndrome," can masquerade as resistant tennis two syndromes occurs in the pain produced on re- elbow. The clinical and pathologic observations in sisted supination. The patient with radial tunnel these two syndromes differ dramatically, and sort- syndrome will experience a reproduction of symp- ing them out at an early stage should not be dif- toms, with pain at the volar forearm site, when the ficult. It is important to be aware of the possibility extremity is tested on resisted supination with the of radial tunnel syndrome, for if the diagnosis of elbow either flexed or extended (Fig. 3). I have not pain about the elbow is not accurate, therapy may seen pain produced by this maneuver in the patient be misguided and the result disappointing. with tennis elbow. The mechanism of pain produc- The intent of this paper is to outline the clinical tion in this test probably reflects the actual and pathologic observations in radial tunnel syn- pathologic origin of the radial tunnel syndrome. drome, to describe the differences and similarities Roles and Maudsley have described the patho- of radial tunnel syndrome and tennis elbow, and to logic anatomy involved in the radial tunnel syn- offer various conservative and surgical treatment drome (Fig. 4). This peripheral entrapment neu- modalities. A series of cases reflecting my own ex- ropathy apparently is produced by a pathologic perience with radial tunnel syndrome, an intrigu- thickening of the upper border of the supinator ing and recently recognized malady, will be re- muscle. At this site, the motor branch of the radial viewed. nerve travels dorsally to enter the posterior part of The syndrome of tennis elbow can manifest itself the forearm and provide motor innervation to the and persist with pain about the medial, or, more extensors of the wrist and digits. The entrapment commonly, the lateral epicondyle of the humerus. phenomenon is similar to that of the carpal tunnel
Tennis elbow and radial tunnel syndrome 823/93 and appears to have a mechanical basis. A patient with radial tunnel syndrome often will report a history not unlike that of tennis elbow. As a rule a major traumatic event is not involved. Usually there is a background of moderately heavy labor or repetitious rotary maneuvers such as assembly or – - sewing heavy fabrics. Pain often is of long dura- tion, more than 6 months, and work loss is variable. Management should itiblude a rilutine workup with thorough history taking and physical exami- nation to confirm that the abnormality is indeed a local phenomenon. Roentgenographic survey and Fig. 1. Middle finger test. electromyographic (EMG) studies are advisable. A patient with radial tunnel syndrome typically will show no alteration from normal in roentgeno- graphic studies of soft tissue or the architecture of bones and joints. An EMG survey also will give normal results, and may be useful for ruling out a .:- more proximal lesion. Like carpal tunnel syn- drome, radial tunnel syndrome may be diagnosed clinically. Once the diagnosis is established, treat- ment is conservative at first. Rest, avoidance of ..l..1.• aggravating activities, application of ice, oral ad- Fig. 2. Site of pain in radial tunnel syndrome. ministration of anti-inflammatory agents, and use of analgesics and supportive devices such as an elastic band usually will produce a satisfactory result. Diminution of the pain symptom complex and resumption of some work activity can be an- ticipated. Local injection of a corticosteroid prep- aration on occasion has produced temporary ameli- oration of pain and allowed improvement in range of motion. Most patients respond favorably to conservative treatment. However, several of my patients did not
Fig. 3. Sites of pain produced by resisted supination. progress satisfactorily on conservative treatment, and I have resorted to a surgical approach in the belief that the etiologic process is mechanical. As in carpal tunnel syndrome, with the flexor retinacu- lum at the volar part of the wrist effecting the mechanical "squeeze" of the median nerve, it ap- pears that the terminal motor branch of the radial nerve can undergo mechanical pressure as it dives below the supinator muscle. I have employed the surgical procedure described by Roles and Maud- sley and by Lister and colleagues 2 in a small series and will offer information on the efficacy of this surgical approach when the condition is recalci- trant to conventional measures. Fig. 4. Anatomy of radial tunnel, adapted from Roles and Maudsley. A, On the proximal border of the deep radial nerve in Surgical procedure the radial tunnel are the biceps and brachialis muscles, and on The procedure is relatively uncomplicated. Explo- the lateral border the brachioradialis. B, As the nerve progresses distally, it splits into the uolar and medial superficial sensory ration is performed through a lazy "S" incision 4 branch and the deep and lateral motor branch, the posterior cm. long and centering about the palpable neck of interosseous nerve. C, The tunnel ends as a deep motor branch the radius at the proximal radial volar portion of and dives under the pathologically thickened upper border of the supinator muscle. At this site the nerve may become entrapped the forearm (Fig. 5). The fascia is incised to reveal and produce the pain of radial tunnel syndrome. the belly of the brachioradialis muscle, which is