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.