Anatomical Study of the Surgical Approaches to the Radial Tunnel

Current concepts of surgical approach for radial nerve entrapment around the elbow

Radial nerve entrapment is an uncommon diagnosis. The entrapment can occur at any location within the course of the nerve distribution, but the most frequent location of entrapment occurs around the elbow and involves the posterior interosseous nerve. Several potential sites of radial nerve entrapment around the elbow are identified: the capsular tissue of the radiocapitellar joint; hypertrophic crossing branches of leash of henry; the leading proximal tendinous and medial edge of extensor carpi radialis brevis; the arcade of Frohse and distal border of the supinator between its two heads. The arcade of Frohse is the most common site of compression. The aim of this manuscript is to describe the common surgical methods to approach the radial nerve entrapments around the elbow and define the preferred surgical approach based on the site of compression.

Posterior Interosseous Nerve Compression in the Forearm, AKA Radial Tunnel Syndrome: A Clinical Diagnosis

BACKGROUND

Posterior interosseous nerve (PIN) compression in the forearm without motor paralysis is a challenging clinical diagnosis. This retrospective study evaluated the clinical assessment, diagnostic studies, and outcomes following surgical decompression of the PIN in the forearm.

METHODS

This study reviewed 182 patients' medical charts following PIN decompression between 2000 and 2020 by a single surgeon. After exclusion of combined nerve entrapments, polyneuropathy, motor palsy, or lateral epicondylitis, the study included 14 patients. Data collected included: clinical presentation and pain drawings, provocative testing, functional outcomes, and Disabilities of the Arm, Shoulder, and Hand (DASH) scores.

RESULTS

There were 15 PIN decompressions (14 patients, mean follow-up = 11.9 months). Clinical presentation included pain (n = 14) (proximal dorsal forearm, n = 14; distal forearm over radial sensory nerve, n = 3) and positive clinical tests (sensory collapse test over the radial tunnel, n = 8; pain with forearm pronation and compression over the radial tunnel, n = 10; Tinel sign, n = 5). Postoperatively, there were significant improvements in Visual Analog Scale pain scores (6.7 to 3.3, P = .0006), quality-of-life scores (74.7 to 32.7, P = .0001), and DASH scores (46.3 to 33.6, P = .02).

CONCLUSIONS

The PIN compression in the forearm without motor paralysis is a clinical diagnosis supported by pain drawings, pain quality, and provocative tests. Patients with persistent, therapy-resistant dorsal forearm pain should be evaluated for PIN compression. Surgical decompression provides statistically significant quantifiable improvement in pain and quality of life.

Radial Tunnel Syndrome: Case Report and Comprehensive Critical Review of a Compression Neuropathy Surrounded by Controversy

Radial tunnel syndrome (RTS) is an uncommon controversial entity thought to cause chronic lateral proximal forearm pain due to compression of the deep branch of the radial nerve, without paralysis or sensory changes. Diagnostic confusion for pain conditions in this region results from inconsistent definitions, terminology, tests, and descriptions in the literature of RTS and "tennis elbow," or lateral epicondylitis. A case of bilateral RTS with signs discordant with traditionally used clinical diagnostic tests was successfully relieved with surgical decompression and led us to perform a comprehensive critical review of the condition. We delineate the controversy surrounding its diagnosis and aim to facilitate appropriate management and identify other areas for further study in this controversial condition. Clinical validity and evidence of anatomical rationale for the traditionally used Maudsley's provocative test is unclear in diagnosis of RTS or in chronic lateral elbow pain, if at all. Neither imaging nor electrophysiological studies contribute to a clinical diagnosis which is supported by short-term improvement after an injection with long-acting local anesthetic and corticosteroid. Accurate diagnosis and treatment of RTS can significantly improve quality of life, but validity and evidence for traditional clinical tests and definitions must be clarified.

Impinging exostoses of the proximal radius: a report of two cases with distinct clinical features

Owing to the rotatory motion of proximal radius and the closely apposed anatomic structures, cortically based osseous lesions at the level of the proximal forearm may produce symptomatic impingement. While osseous impingement onto the adjacent proximal ulna may result in limited forearm rotation, impingement on the surrounding soft-tissue structures may produce symptoms as well. Here, we describe two cases of symptomatic proximal radius exostosis, each of which produced distinct clinical symptoms. In the first case, impingement on the posterior interosseous nerve produced symptoms of radiating forearm pain and paresthesia resembling radial tunnel syndrome. In the second case, impingement of the exostosis on the distal biceps tendon resulted in painful mechanical snapping with rotation of the forearm. In both cases, symptoms rapidly improved after surgical excision.

Anatomy of the Posterior Antebrachial Cutaneous Nerve, Revisited

PURPOSE

To describe the branching pattern of the posterior antebrachial cutaneous nerve (PABCN) and to corroborate measurements and observations reported by previous authors.

METHODS

Using 28 fresh-frozen cadaver specimens, we dissected the PABCN from its origin from the radial nerve to its terminal arborization in the distal forearm. Measurements relative to the lateral humeral epicondyle were recorded. The course of the nerve over the muscles of the mobile wad and its branching pattern in the proximal forearm were noted.

RESULTS

The PABCN originated from the radial nerve at a mean of 14.2 cm proximal to the lateral epicondyle. The fascial hiatus through which the PABCN emerged to become superficial was a mean of 8.2 cm proximal to the lateral epicondyle. All specimens had at least 1 longitudinal branch that passed a mean of 2.8 cm anterior to the lateral epicondyle. Thirty-two percent of specimens had a lesser proximal branch in the distal third of the lateral arm; 86% had an epicondylar branch to the lateral epicondyle; and 21% had a second longitudinal branch. Ninety-three percent had a longitudinal branch coursing over the interval between the brachioradialis and the extensor carpi radialis longus in the proximal forearm.

CONCLUSIONS

After becoming superficial in the distal brachium, the PABCN typically gives off a discrete epicondylar branch and then continues distally in the forearm as 1 or 2 longitudinal branches. In addition, in the proximal third of the forearm, a consistent longitudinal branch of the PABCN courses over the interval between the brachioradialis and the extensor carpi radialis longus. This review confirms previous observations of the PABCN.

CLINICAL RELEVANCE

Knowledge of the course of the PABCN will assist surgeons in identifying and avoiding injury in clinical situations such as plating the proximal radius or releasing the radial tunnel.

Transbrachioradialis Approach to the Radial Tunnel: An Anatomic Study of 5 Potential Compression Sites

BACKGROUND

Recent anatomic studies have failed to demonstrate a single utilitarian approach to intraoperative identification and surgical release of all 5 potential sites of posterior interosseous nerve (PIN) compression in the radial tunnel. This study examines if a single incision brachioradialis-splitting approach without the use of additional anatomic windows is capable of adequately exposing the entire length of the radial tunnel, including all 5 sites of PIN compression to allow for adequate release.

METHODS

Ten fresh frozen cadaver forearms (6 female, 4 male) were dissected utilizing a curvilinear 7 cm incision over the brachioradialis. The muscle belly was split via simple blunt retraction, exposing the radial tunnel. The PIN was identified and mobilized at 5 compression sites: radiocapitellar joint (RCJ), radial recurrent vessels (Leash of Henry), fibrous medioproximal edge of extensor carpe radialis brevis, arcade of Frohse, and distal edge of supinator.

RESULTS

The PIN was identified and effectively released in all specimens without difficulty from this single approach. All 5 sites of compression were visible and accessible through the brachioradialis-split approach. Specifically, there was no difficulty in identifying and releasing the PIN at the distal edge of supinator.

CONCLUSIONS

Radial tunnel syndrome is defined as PIN compression within the radial tunnel spanning from the fibrous RCJ to the distal edge of the supinator. A single brachioradialis-splitting approach is adequate for complete visualization and release of all compression sites of the radial tunnel. Utilizing this technique allows for surgical access and ease as well as minimizing necessity for additional windows or multiple incisions.