History and Physical Examination
Radial nerve palsy
Radial nerve palsy in the middle third of the arm is characterized by palsy or paralysis of all extensors of the wrist and digits, as well as the forearm supinators. Very proximal lesions also may affect the triceps. Numbness occurs on the dorsoradial aspect of the hand and the dorsal aspect of the radial three-and-a-half digits. Sensation over the distal and lateral forearm is supplied by the lateral antebrachial cutaneous nerve and therefore is preserved. [13, 14, 15, 16, 17]
Radial tunnel syndrome
Radial tunnel syndrome is characterized by pain over the anterolateral proximal forearm in the region of the radial neck. This syndrome often appears in individuals whose work requires repetitive elbow extension or forearm rotation. The maximum tenderness is located four fingerbreadths distal to the lateral epicondyle. (By way of comparison, with lateral epicondylitis, maximum tenderness is usually directly over the epicondyle.) Symptoms are intensified by extending the elbow and pronating the forearm. In addition, resisted active supination and extension of the long finger cause pain. Weakness and numbness usually are not demonstrated. [18, 19, 20]
Posterior interosseous nerve syndrome
Patients with posterior interosseous nerve syndrome present with weakness or paralysis of the wrist and digital extensors. Pain may be present, but it usually is not a primary symptom. Attempts at active wrist extension often result in weak dorsoradial deviation as a consequence of preservation of the radial wrist extensors but involvement of the extensor carpi ulnaris and extensor digitorum communis. These patients do not have a sensory deficit.
Rarely, compression of the posterior interosseous nerve may occur after bifurcation into medial and lateral branches. Selective medial branch involvement causes paralysis of the extensor carpi ulnaris, extensor digiti quinti, and extensor digitorum communis. With compression of the lateral branch, paralysis of the abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis proprius is noted.
Wartenberg syndrome
Patients with the diagnosis of Wartenberg syndrome complain of pain over the distal radial forearm associated with paresthesias over the dorsal radial hand. They frequently report symptom magnification with wrist movement or with tight pinching of the thumb and index digit. These individuals demonstrate a positive Tinel sign over the radial sensory nerve and local tenderness. Hyperpronation of the forearm can cause a positive Tinel sign. A high percentage of these patients reveal physical examination findings consistent with de Quervain tenosynovitis.
