Radial Tunnel Syndrome by Tim Bertelsman & Brandon Steele
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Radial Tunnel Syndrome by Tim Bertelsman & Brandon Steele. © ChiroUp 2018 Radial Tunnel Syndrome Evaluation The radial tunnel is defined as the space surrounding the radial nerve as it traverses the posterior forearm from the radiocapitellar joint thru the supinator • Radial Nerve Test muscle. (1) “Radial tunnel syndrome” describes symptoms generated from irrita- • Radial Tunnel Compression tion or compression of the radial nerve within this 2” tunnel. • Resisted Forearm Supination Test • Resisted Long Finger Extension There are multiple potential sites of compression in the radial tunnel that may Test affect the sensory branch of the radial nerve, the motor branch- also called the Management Soft Tissue posterior interosseous nerve, or both. (2) Compression of the superficial sensory branch results in purely sensory symptoms while compression of the posterior • Nerve Floss- Radial interosseous nerve produces motor weakness of the finger, hand and wrist • Nerve Release- Radial Nerve at the extensors. Elbow • STM- Brachioradialis • STM- Supinator • STM- Wrist Extensors Phase I exercises • Radial Nerve Floss • Clasp Stretch • Wrist Extensor Stretch- Table • Brachioradialis Stretch • Supinator Stretch Clinical Pearls • Radial nerve compression oc- curs most commonly (70%) beneath the proximal edge of the supinator muscle at the Arcade of Froshe. • 10% of patients with lateral epicondylitis have co-existent radial tunnel syndrome. • 70% of patients with lateral elbow pain demonstrate symptoms or posi- tive clinical findings in the cervical or upper thoracic regions. • Use of a tennis elbow counterforce The most common site of compression within the radial tunnel is beneath a brace is contraindicated for radial thickened, fibrous proximal edge of the supinator muscle, also called the arcade tunnel patients. of Froshe. This thickening is thought to be developmental as a result of repeti- • Nocturnal pain is common in radial tive strain and is present in 30-80% of the population. (3,4) Compression of tunnel syndrome but not in lateral the posterior interosseous nerve beneath the arcade of Froshe is sometimes epicondylitis. referred to as “Supinator syndrome” and accounts for almost 70% of all radial tunnel presentations. (3) Other sites of entrapment include the distal border of the supinator muscle and beneath the origin of the extensor carpi radialis brevis muscle. (5,6) Radial tunnel syndrome occurs less frequently than its more common upper extremity cousins- carpal tunnel syndrome and cubital tunnel syndrome. (7,8) Radial tunnel syndrome frequently accompanies these and other co-morbities including: pro- nator syndrome, Guyons syndrome, medial epicondylitis, de Quervain’s tenosynovitis, trigger finger and lateral epicondylitis. (9) Research suggests that up to 10% of patients with lateral epicondylitis have co-existent radial tunnel syndrome. (10) Radial tunnel syndrome is thought to result from overuse, especially excessive wrist extension, pronation or supination. (27) Radial Tunnel Syndrome (Continued) Presenting symptoms depend on whether irritation affects the sensory branch, motor branch or both. Compression or ir- ritation of the superficial sensory branch results in pain, paresthesia or diminished sensitivity along the dorsal aspect of the forearm sometimes radiating to the hand, including the first web space and back of the thumb and index finger. (11) These symptoms are often described as deep, aching and diffuse, sometimes mimicking lateral epicondylitis. (12) Compression of the posterior interosseous nerve (motor branch) manifests as weakness of metacarpophalangeal joint extension and thumb extension, also called “finger drop”. (2) Wrist extension is generally not affected as noticeably because of cross-innervation. Deeply palpating and rolling your fingers over the radial nerve four finger breaths distal to the lateral epicondyle should pro- voke symptoms (Radial tunnel compression test). (13) Symptoms are generally intensified by resisted wrist extension, supina- tion and pronation. Resisted muscle testing can help localize the site of compression. (14) Reproduction of symptoms upon resisted supination, when the arm and wrist are in extension, suggests compression at the arcade of Froshe. (Resisted supina- tion test) Reproduction of symptoms during resisted extension of the middle finger suggests compression of the posterior interosseous nerve beneath the extensor carpi radialis brevis (Resisted long finger extension, aka, Middle finger sign). (13) Tinel sign or reproduction of symptoms by percussion of the radial nerve is infrequently present. Seventy percent of patients with lateral elbow pain demonstrate symptoms or positive clinical findings in the cervical or upper thoracic regions. Positive findings include limited range of motion in flexion and extension and positive provocation testing. (15) Neurodynamic testing/ tensioning of the radial nerve may provoke symptoms. Palpation elicits tenderness over the radial nerve and sometimes over the lateral epicondyle making differentiation of the two conditions challenging. The pain of radial tunnel syndrome should be more acute distally. (16) Nocturnal pain is more com- mon in radial tunnel patients than those with lateral epicondylitis. (17) Other differential diagnostic considerations for radial tunnel syndrome include: Wartenberg’s syndrome/ cheiralgia paresthetica (aka “handcuff neuropathy” from compression of the distal radial nerve) brachial plexus injury, cervical radiculopathy, de Quervain’s tenosynovitis, bone pathology, elbow bursitis, elbow sprain/strain/tendinopathy, peripheral neuropathy and thoracic outlet syndrome. Radiographs are seldom indicated unless needed to rule out osseous pathology. Ultra- sound and MRI may be used to detect space occupying lesions and to localize the spe- cific site of nerve involvement. (18,19) EMG/ NCS studies are typically negative but may highlight muscle innervation deficits in cases with significant posterior interosseous nerve involvement. (20,21) Conservative management of radial tunnel syndrome is generally successful. (22) Initial management of radial tunnel syndrome includes anti-inflammatory measures, rest and avoidance of aggravating activities. Ice, ice massage and electrotherapy may provide benefit. Pulsed ultrasound has been shown to be effective in the management of other upper extremity compressive neuropathies. The suggested settings are: frequency – 1 MHz; intensity – 1 watt/cm squared; duty cycle – 25%. (23) Patients should limit excessive or repetitive wrist extension, forearm pronation, and supination. Splinting may be used in more severe cases. (24) Sources of external compression should be identified and removed. A tennis elbow counter-force brace, commonly used in the treatment of lateral epicondylitis, will likely aggravate the symptoms of radial tunnel syndrome. (25) Radial Tunnel Syndrome (Continued) Soft tissue manipulation and nerve flossing are useful tools in the management of radial tunnel syndrome. Good clinical judg- ment is required to assess the point at which benefits of soft tissue mobilization outweigh the risks of symptom exacerbation. When the symptoms are no longer acute, stretching and myofascial release techniques should be directed at the supinator, brachioradialis and wrist extensors, including the extensor carpi radialis brevis. Nerve flossing is thought to enhance the neu- rodynamic flexibility of a nerve by releasing adhesions. Nerve flossing should not provoke symptoms. Radial nerve flossing is performed with the patient standing, shoulder blade pressed down, and wrist flexed with the fingers pointing backwards, i.e., Butler tip position, while bending the head in the contralateral direction and reaching back with the arm. Since cervical and up- per thoracic involvement is common, clinicians should assess for and manipulate any spinal restrictions. (15) Surgery may be indicated for patients who fail 12 weeks of conservative care or in those with significant motor deficit. (26) References 1. Rosenbaum R: Disputed radial tunnel syndrome. Muscle Nerve 1990, 22:960-967 2. Kirici Y, Irmak MK: Investigation of two possible compression sites of the deep branch of the radial nerve and nerve supply of the extensor carpi radialis brevis muscle. Neurol Med Chir (Tokyo) 2004, 44:14-18. 3. Ferdinand, B.D., Rosenberg, Z.S., Schweitzer, M.E., Stuchin, S.A., Jazrawi, L.M., Lenzo, S.R., Jul 2006. MR imaging features of radial tunnel syndrome: initial experience. Radiology 240 (1), 161e168 4. Clavert P, Lutz JC, Adam P, Wolfram-Gabel R, Liverneaux P, Kahn JL. Frohse’s arcade is not the exclusive compression site of the radial nerve in its tunnel. Orthop Traumatol Surg Res 2009; 95:114 –118 5. Portilla Molina AE, Bour C, Oberlin C, et al. The posterior interosseous nerve and the radial tunnel syndrome: an anatomical study. Int Orthop.1998 ;22:102–106. 6. Roles NC, Maudsley KH. Radial tunnel syndrome: resistant tennis elbow as nerve entrapment. J Bone Joint Surg Br.1972 ;54:499–508. 7. Loh YC, Lam WL, Stanley JK, Soames RW: A new clinical test for radial tunnel syndrome - the Rule-of-Nine test: a cadaveric study. J Orthop Surg (Hong Kong) 2004, 12:83-86 8. Latinovic R, Gulliford MC, Hughes RA. Incidence of common compressive neuropathies in primary care. J Neurol Neurosurg Psy- chiatry 2006;77:263–265 9. John Houle , Matthew J Concannon , Michael Neumeister , Richard Brown , Bradon Wilhelmi. Upper Extremity Co-Morbidities in Patients with Radial Tunnel Syndrome. J reconstr Microsurg 2005;