High-Resolution Sonography of Posttraumatic Neuroma of the Superficial Radial Nerve

Introduction The superficial radial nerve (SRN) is a sensory branch of the radial nerve which supplies the dorsolateral aspect of the hand and the first 3 digits. The radial nerve, a nerve with mixed fibers, branches into the pure motor posterior interosseous nerve and the pure sensory superficial radial nerve just above the arcade of Frohse in the proximal forearm. In the distal forearm, the superficial radial nerve transverses a superficial subcutaneous course between the tendons of the brachioradialis and extensor carpi radialis longus muscles as it crosses the lateral edge of the radius. Many factors may contribute to the development of a lesion of the SRN. The most common anatomic site of compression corresponds to the area of transmission of the nerve from its submuscular position beneath the brachioradialis muscle to its subcutaneous position on the surface of the extensor carpi radialis longus muscle. In patients with de Quervain tendosynovitis, secondary irritation of the SRN is frequent. Other common causes include postsurgical injury, external compression and trauma [ 1 ]. Patients usually complain of therapy-resistant pain and, consequently, inability to work. Surgery is considered in recalcitrant pain syndrome. Lesions of the SRN are characterized by tenderness on percussion, positive Hoffmann-Tinel-sign, electrifying pain, allodynia and paresthesias in the area of innervation. The diagnosis is based substantially on clinical presentation. Nerve conduction studies are usually performed to confirm the diagnosis; however, often there are false negative results with difficulty to identify the exact site of the lesion [ 2 ] [ 3 ]. The SRN, although small in size, can be visualized with high-resolution sonography using specific landmarks [ 4 ]. This report describes the role of high-resolution sonography in the study of traumatic neuromas of the superficial radial nerve and the postoperative result for the first case.