Radial tunnel syndrome: definition, distinction and treatments

Establishing the diagnosis of radial tunnel syndrome: a systematic review of published clinical series

PURPOSE

Radial tunnel syndrome (RTS) is a controversial diagnosis due to non-specific exam findings and frequent absence of positive electromyography (EMG) and nerve conduction study (NCS) findings. The purpose of this study was to identify the methods used to diagnose RTS in the literature.

METHODS

We queried PubMed, Embase, Web of Science, and Cochrane databases per PRISMA guidelines. Extracted data included article and patient characteristics, diagnostic assessments utilized and their respective findings, and treatments. Objective data were summarized descriptively. The relationship between reported diagnostic findings (i.e., physical exam and diagnostic tests) and treatments was assessed via a descriptive synthesis.

RESULTS

Our review included 13 studies and 391 upper extremities. All studies utilized physical exam in diagnosing RTS; most commonly, patients had tenderness over the radial tunnel (381/391, 97%). Preoperative EMG/NCS was reported by 11/13 studies, with abnormal findings in 8.9% (29/327) of upper extremities. Steroid and/or lidocaine injection for presumed lateral epicondylitis was reported by 9/13 studies (46/295 upper extremities, 16%), with RTS being diagnosed after patients received little to no relief. It was also common to inject the radial tunnel to make the diagnosis (218/295, 74%). The most common reported intraoperative finding was narrowing of the PIN (38/137, 28%). The intraoperative compressive site most commonly reported was the arcade of Frohse (142/306, 46%).

CONCLUSIONS

There is substantial heterogeneity in modalities used to diagnose RTS and the reported definition of RTS. This, in conjunction with many patients having concomitant lateral epicondylitis, makes it difficult to compare treatment outcomes for RTS.

LEVEL OF EVIDENCE

Level III. Systematic review of retrospective and prospective cohort studies.

Nomenclature of the radial nerve: distinguishing between the deep branch of the radial nerve and the posterior interosseous nerve

To address an inconsistency in the nomenclature of the anatomy and compressive syndromes of the deep branch of the radial nerve, we advocate for a single compression syndrome that presents along a spectrum from pain to posterior interosseous nerve palsy.

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.

The Epidemiology of Radial Tunnel Syndrome and Its Overlap With Lateral Epicondylitis

PURPOSE

Radial tunnel syndrome (RTS) is characterized by nerve compression affecting the posterior interosseous nerve branch in the forearm, and its symptoms often overlap with those of lateral epicondylitis (LE). The purpose of this study was to examine the epidemiology of RTS, frequency of injections and surgical release, and overlap of RTS with LE.

METHODS

We queried the PearlDiver database to identify RTS in patients older than 18 years. Demographic data, diagnostic or therapeutic injection within 30 days of diagnosis, surgical release within 1 year of diagnosis, and 90-day postoperative complication rates were evaluated. Using International Classification of Diseases, 10th Revision, laterality codes, we also determined the number of patients who had same-side RTS and LE and the proportion of patients who subsequently underwent simultaneous RT release and LE debridement.

RESULTS

The prevalence of RTS in a representative United States insurance database was 0.091%, and the annual incidence was 0.0091%. There were 75,459 patients identified with an active RTS diagnosis. The mean age at the time of diagnosis was 52 years (range, 18-81 years), 55% were women, and 1,833 patients (2.4%) underwent RT release within 1 year. Fewer than 3% of the patients received an injection within 30 days of RTS diagnosis. The 90-day postoperative complication rates were low: 5% of the patients required hospital readmission and 2.1% underwent revision surgery. Approximately 5.7% of the patients with RTS also had a diagnosis of LE on the same side within 6 months of RTS diagnosis. In patients with ipsilateral RTS and LE who underwent surgery, 59.1% underwent simultaneous RT release and LE debridement, whereas 40.9% underwent isolated radial tunnel release.

CONCLUSIONS

The analysis of a large insurance database showed that the diagnosis of RTS is rarely assigned, suggesting that the incidence of this nerve compression is low.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

10 Hypotheses in Hand Surgery

I have put together 10 topics and labeled them as hypotheses, which outline my preferred practices. The topics relate to questionable nerve compression, double crush syndrome of nerves, motion therapy after surgery, delayed primary tendon repair, proximal pole fracture of the scaphoid, short splint, and indications for postoperative hand elevation. I found no proof whether my preferred methods are better than or inferior to alternative methods that others use. The 10 hypotheses are presented to stimulate thinking, clinical observation, or investigations and highlight several areas of research. Investigation into these hypotheses may avoid unnecessary treatment or improve postsurgical comfort for patients and long-term outcomes of treatment.

Some Misconceptions in the Treatment of Cubital Tunnel Syndrome, Radial Tunnel Syndrome, and Median Nerve Compression in the Forearm

This article discusses ulnar, median, and radial nerve compression in the proximal forearm and elbow and some possible common misconceptions. In particular, the ligament of Struthers extremely rarely causes ulnar neuropathy. Lacertus syndrome and flexor superficialis-pronator syndrome can be diagnosed separately. Surgical release can be through a small incision. Acronyms for compression to radial nerve in proximal forearm can be simplified to radial tunnel syndrome, which includes a mild type (classical radial tunnel syndrome) and a severe type (posterior interosseous nerve (PIN) compression).