What are the diagnostic and treatment options for radial tunnel syndrome?

Diagnosing and Treating Radial Tunnel Syndrome

Surgical decompression of the radial nerve is the most effective treatment for refractory radial tunnel syndrome that has failed conservative management. 1

Diagnosis

Clinical Presentation

• Pain in the forearm and hand without motor weakness, often exacerbated by activities involving repetitive wrist and forearm movements 1, 2
• Symptoms may be confused with lateral epicondylitis (tennis elbow), but pain is typically more distal and located over the radial tunnel 3
• Chronic lateral elbow pain that doesn't respond to typical tennis elbow treatments should raise suspicion for radial tunnel syndrome 4

Physical Examination

• Reproduction of symptoms with pressure over a palpable tender spot along the course of the radial tunnel 2
• Pain with resisted supination or resisted middle finger extension 2
• Relief of symptoms after local anesthetic infiltration of the tender area (diagnostic confirmation) 2
• Positive upper limb neural tension test with radial nerve bias (ULNT2b) 4
• The presence of at least two of these objective signs is necessary for diagnosis 2

Diagnostic Imaging

• There is no definitive imaging study for radial tunnel syndrome 3
• Imaging is primarily used to rule out other conditions such as lateral epicondylitis, cervical radiculopathy, or space-occupying lesions 3

Treatment

Conservative Management (First-Line)

• Anti-inflammatory medications to reduce pain and inflammation 4
• Activity modification to avoid aggravating movements 1, 4
• Splinting to rest the affected area 1
• Corticosteroid injections at the point of maximal tenderness 2
  • Long-term relief was achieved in 16 out of 25 cases (64%) with steroid injection 2
• Physical therapy focusing on nerve mobilization techniques 4
• Dry needling has shown promise in case reports for managing radial tunnel syndrome 4

Surgical Management

• Indicated when conservative measures fail after an adequate trial (typically 3-6 months) 1, 2
• Surgical decompression involves:
  • Identification of the interval between the brachioradialis and extensor carpi radialis longus muscles 1
  • Location and protection of the radial sensory nerve 1
  • Identification and decompression of the posterior interosseous nerve 1
  • Division of the fascia of the extensor carpi radialis brevis and careful division of the supinator muscle to decompress the posterior interosseous nerve 1
• Surgical outcomes:
  • Complete relief of pain was achieved in 7 out of 9 surgical cases (78%) in one study 2
  • Significant reduction in pain was reported at 7-month follow-up in another case 1

Treatment Algorithm

1. Initial Presentation: Begin with conservative management

   • NSAIDs
   • Activity modification
   • Splinting
   • Physical therapy

2. Persistent Symptoms (4-6 weeks): Consider corticosteroid injection 2

3. Refractory Cases (3-6 months of failed conservative treatment):

   • Confirm diagnosis with local anesthetic injection test 2
   • Consider surgical decompression of the radial nerve 1, 2

Pitfalls and Caveats

• Misdiagnosis is common as symptoms can mimic lateral epicondylitis 3
• There is a lack of high-quality controlled studies on the effectiveness of both conservative and surgical treatments 5
• The absence of a clear diagnostic protocol makes diagnosis challenging 5
• Nerve conduction studies may be normal in radial tunnel syndrome, making clinical examination crucial for diagnosis 3
• Surgical decompression should only be considered after failure of conservative management, as it carries risks including nerve injury 1, 2