Radial Nerve Injury at the Elbow

Aka: Radial Nerve Injury at the Elbow, Radial Tunnel, Radial Tunnel Syndrome, Posterior Interosseous Nerve Syndrome, Posterior Interosseus Nerve Injury at the Elbow, Wartenberg's Syndrome, Neurogenic Tennis Elbow

1. See Also
   1. Radial Nerve Injury at the Humerus (Saturday Night Palsy, Crutch Palsy, Wrist Drop)
   2. Radial Nerve Injury at the Elbow
   3. Radial Nerve Injury at the Wrist
   4. Peripheral Nerve Injury
2. Causes
   1. Repetitive Forearm supination and pronation
      1. Carpenters
      2. Mechanics
   2. Lateral elbow compression of the Radial Nerve
      1. Results in radial nerve Entrapment Neuropathy
3. Pathophysiology
   1. Radial Nerve divides at the lateral elbow into two branches
      1. Superficial branch (Sensory only)
      2. Posterior interosseus nerve (Deep branch, motor resulting in wrist extension weakness)
   2. Lesion of the Radial Nerve before splitting into superficial sensory and deep motor components
      1. May result in combined sensory and motor deficits
4. Symptoms
   1. Radial Tunnel (superficial branch compression, sensory only, Wartenberg's Syndrome)
      1. Gradual onset, or poorly localized Forearm pain at 3-4 cm distal to the lateral epicondyle
         1. Pain extends along the proximal lateral Forearm
      2. Provoked with repetitive Forearm pronation, elbow extension and wrist flexion
   2. Posterior interosseus nerve (Deep branch)
      1. Hand weakness in finger extension (finger drop)
      2. Lipoma or other space occupying lesion are most commonly cause
         1. May also be due to elbow synovitis
5. Signs
   1. Radial Tunnel
      1. Superficial branch compression, sensory only (Wartenberg's Syndrome)
         1. Motor weakness suggests posterior interosseus nerve (Deep branch) compression (see below)
      2. Like Lateral Epicondylitis, Radial Tunnel is exacerbated by Forearm supination and wrist dorsiflexion against resistance
      3. Unlike Lateral Epicondylitis, maximal tenderness is over the anterior radial neck
      4. Positive Tinel sign (tapping over the Radial Tunnel reproduces symptoms)
   2. Posterior interosseus nerve (Deep branch, sensory and motor findings)
      1. Pain features are the same as for Radial Tunnel
      2. Weak finger extension, especially middle finger extension against resistance
      3. Intact wrist extension (but may be weak) with radial deviation at wrist
         1. Preserved by an intact extensor carpi radialis longus
6. Differential Diagnosis: Radial Tunnel (Wartenberg's Syndrome)
   1. Lateral Epicondylitis
7. Management: Radial Tunnel (sensory) and posterior interosseus nerve (motor and sensory)
   1. Eliminate provocative actvities (repetitive motion)
   2. NSAIDs
   3. Physical Therapy
      1. Work on wrist extensor muscles and Forearm supinatory muscles
      2. Start with Stretching after pain has ceased and then gradually introduce strengthening
   4. May respond to a single Corticosteroid Injection
      1. Diagnostic and therapeutic
   5. Cock-up Wrist Splint
      1. Prevent wrist extension
   6. Elbow splint
      1. Indicated for brief use to prevent Forearm supination
      2. Splint with elbow at 90 degrees (risk of loss of elbow range of motion)
   7. Surgical decompression
      1. Consider if lack of improvement at 3-4 months of conservative therapy (motor deficits)
      2. Isolated sensory deficits (Radial Tunnel) rarely warrant surgical intervention
8. References
   1. Hariri (2010) Clin Sports Med 29(4): 655-75 [PubMed]
   2. Huisstede (2008) J Hand Surg Am 33(1): 72-8 [PubMed]
   3. Kane (2014) Am Fam Physician 89(8): 649-57 [PubMed]
   4. Neal (2010) Am Fam Physician 81(2): 147-55 [PubMed]
   5. Silver (2021) Am Fam Physician 103(5): 275-85 [PubMed]