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

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.

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.

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).

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.