Radial Tunnel Syndrome

Abstract

Purpose: Radial tunnel syndrome is defined as a compressive neuropathy of the posterior interosseus nerve. It is differentiated from posterior interosseus nerve compression by symptom profile. The purpose of this article is to review past and current literature on the topic and determine if there are any emerging treatment options for this condition.

Recent findings: Traditionally, conservative management of Radial Tunnel syndrome has been relatively unsuccessful. As a result, patients afflicted by this neuropathy require operative intervention. Effectiveness of surgical decompression is variable and can range from 67 to 92% but currently remains the standard treatment. However, there are some conservative treatment options that have been recently reported that show promising results. Such treatments include dry needling of the affected area and ultrasound guided corticosteroid injections to hydro dissect around the posterior interosseus nerve at sites of compression. Radial tunnel syndrome is an uncommon and unique peripheral neuropathy. It involves the posterior interosseus nerve however it can be differentiated from PIN syndrome based on the symptom profile. There are various compressive etiologies that can cause a patient to become symptomatic; therefore it is important to critically assess the patient and their symptoms and use appropriate imaging to determine the cause and appropriate treatment. Typically, conservative treatments are attempted first. Traditionally, conservative therapy is unsuccessful and operative decompression is necessary. However, current literature highlights various new nonsurgical options that suggest some promise and could be alternatives to surgical decompression.

Keywords: Compression; PIN neuropathy; Posterior interosseous nerve; Proximal forearm pain; Radial tunnel syndrome.

Fig. 1

View of the lateral elbow interval between ECRB (extensor carpi radialis brevis) and EDC (extensor digitorum communis) with underlying supinator. Dotted line indicates the path of the PIN beneath the supinator. Arrowhead indicates the origin of PIN. (Adapted from Knutsen, E. J., & Calfee, R. P. (2013). Uncommon Upper Extremity Compression Neuropathies. Hand Clinics, 29(3), 443–453. 10.1016/j.hcl.2013.04.014)

Fig. 2

Image demonstrating the path of the posterior interosseous nerve through the radial tunnel (Adapted from Simon Perez, C., García Medrano, B., Rodriguez Mateos, J. I., Coco Martin, B., Faour Martin, O., & Martin Ferrero, M. A. (2014). Radial tunnel syndrome: results of surgical decompression by a postero-lateral approach. International Orthopaedics, 38(10), 2129–2135. 10.1007/s00264-014-2441-8)

Fig. 3

Rule of nine test-nine pressure points are marked on the proximal volar aspect of the forearm in 3 columns. Tenderness to palpation over the two proximal lateral points (red) indicates radial nerve irritation. Tenderness over the middle distal points (yellow) indicates proximal median nerve irritation. The remaining points (blue) serve as controls. (Adapted from Moradi A, Ebrahimzadeh MH, Jupiter JB. Radial tunnel syndrome, diagnostic and treatment dilemma. Arch Bone Jt Surg. 2015:3:3:156-162. 10.1155/2012/230679.)

Fig. 4

Coronal T2 weighted MRI cuts of the left elbow demonstrating edema secondary to a partial tear of the common extensor tendon origin at the lateral epicondyle (Image Courtesy of Louis Catalano, MD)

Fig. 5

Axial T2 weight MRI cut of the distal humerus demonstrating edema adjacent to the lateral epicondyle demonstrating lateral epicondylitis (Image Courtesy of Louis Catalano, MD)

Fig. 6

Axial T2-weighted MRI cuts of the proximal radius and ulna demonstrating edema from the common extensor tendon tear at the lateral epicondyle tracking along the PIN within the arcade of Frohse (yellow arrow). The white arrow demonstrates intramuscular edema within the extensor digitorum communis (EDC) that may reflect acute denervation; however there is no obvious atrophy of the musculature (Image Courtesy of Louis Catalano, MD)

Fig. 7

Anterolateral incision over the proximal forearm. Skin incision completed demonstrating structures beneath the skin. Anteriorly is the thin facia (appearing more red) overlying the brachioradialis (BR) and laterally/posteriorly is the thicker fascia overlying the extensor carpi radialis longus (ECRL) (Image Courtesy of Louis Catalano, MD)

Fig. 8

The inset image in the left upper hand corner demonstrates the brachioradialis (BR) and extensor carpi radialis longus (ECRL) muscle bellies once the facia has been incised. The main image demonstrates the fascial plane between BR and ECRL) (Image Courtesy of Louis Catalano, MD)

Fig. 9

This image demonstrates the neural structures between the brachioradialis anteriorly and ECRL posterolaterally. The wide white band deep to the ECRL is the supinator fascia and posterior interosseus nerve (PIN) can be seen diving deep to the supinator fascia. Just anterior to the PIN a branch can be seen which is the nerve to extensor carpi radialis brevis (ECRB). Anterior to this, deep to the brachioradialis is the superficial radial nerve that has branched with the PIN from the radial nerve proximal to this exposure. ) (Image Courtesy of Louis Catalano, MD)

Fig. 10

The inset in the left upper hand corner demonstrates the same image as that shown in Fig. 9 to reiterate the location of the supinator fascia. The main image shows the supinator fascial incised (white box demonstrates where the fascia was located prior to decompression). The decompressed PIN can now be seen diving deep into the supinator muscle belly. The superficial radial nerve can be seen coursing from proximal to distal along the lateral border of the brachioradialis. Between the PIN and superficial radial nerve, the terminal branch nerve to ECRB can be seen inserting into the muscle belly (Image Courtesy of Louis Catalano, MD)