How do you differentiate and treat epicondylitis versus nerve entrapment in a patient presenting with lateral elbow pain and numbness or tingling in the hand or arm?

Differentiating and Treating Epicondylitis versus Nerve Entrapment

For lateral elbow pain with numbness or tingling, perform the resisted wrist extension test (RWET) with the elbow extended and forearm pronated, and assess for sensory disturbance in the superficial radial nerve distribution—63% of lateral epicondylitis cases have associated nerve involvement, making these conditions frequently coexistent rather than mutually exclusive. 1

Clinical Differentiation

Key Distinguishing Features

Lateral Epicondylitis Presentation:

• Pain at the lateral epicondyle from repetitive wrist extension, radial deviation, and forearm supination, affecting the extensor carpi radialis brevis tendon primarily 2
• Pain radiates toward the thumb following the anatomic distribution of the extensor carpi radialis brevis and longus tendons 2
• Affects dominant arm in 75% of cases, most commonly after age 40 2
• RWET has 100% positivity when performed with elbow extended and forearm pronated (EP position), compared to only 24% in elbow flexed/forearm supinated position 1

Nerve Entrapment Indicators:

• Sensory disturbance in the superficial radial nerve territory occurs in 63.2% of lateral epicondylitis patients, compared to only 2.9% of controls 1
• For ulnar nerve involvement: characteristic dislocation and relocation of the nerve at the elbow during flexion and extension of the forearm 3
• Post-traumatic ulnar nerve dislocation can be misdiagnosed as medial epicondylitis or early-stage ulnar nerve entrapment 3

Critical Diagnostic Pitfall

The most important clinical caveat: these conditions frequently coexist rather than being mutually exclusive. Sensory disturbance of the superficial radial nerve is present in 63.2% of lateral epicondylitis cases, and this incidence is significantly higher (74.5%) in patients who have not received corticosteroid injections 1. Post-traumatic ulnar nerve dislocation is commonly overlooked and misdiagnosed as medial epicondylitis 3.

Diagnostic Workup Algorithm

Step 1: Initial Imaging

• Begin with plain radiographs of the elbow (sensitivity 76%, specificity 50% for tendon pathology) to rule out intra-articular bodies, heterotopic ossification, osteochondral lesions, soft tissue calcification, occult fractures, and osteoarthritis 2

Step 2: Advanced Imaging When Radiographs Normal or Indeterminate

For suspected tendon pathology:

• Ultrasound is the preferred modality with sensitivity 64.25%, specificity 85.19%, and accuracy 72.73% for common extensor tendon tears 4
• Advanced ultrasound techniques (sonoelastography combined with superb microvascular imaging) achieve sensitivity 94%, specificity 98%, and accuracy 96% 4
• MRI without IV contrast is equivalent alternative with sensitivity 90-100% and specificity 83% for epicondylalgia 5

For suspected nerve entrapment:

• Dynamic ultrasound of the ulnar nerve in two positions (flexion and extension) clearly demonstrates ulnar nerve dislocation 3
• MRI demonstrates associated findings including radial collateral and lateral UCL injuries 5

Step 3: Diagnostic Nerve Block

• For chronic lateral epicondylitis not responding to conservative treatment, perform diagnostic nerve block of the posterior branches of the posterior cutaneous nerve of the forearm proximal to the lateral humeral epicondyle 6
• Positive response (improvement in grip strength and pain) predicts 80% success rate with denervation surgery 6

Treatment Algorithm

Conservative Management (First-Line for Both Conditions)

Initial 3-6 months:

• Relative rest, activity modification, and eccentric strengthening exercises as foundation—leads to recovery in 80% of cases 2
• Eccentric strengthening combined with manual joint mobilization and exercise therapy for optimal results 2
• NSAIDs provide short-term pain relief but do not affect long-term outcomes 2
• Corticosteroid injections are more effective than NSAIDs in acute phase but do not change long-term outcomes 2

Important caveat: Corticosteroid injection decreases the incidence of associated sensory disturbances (48.3% vs 74.5% without injection), suggesting potential benefit for nerve-related symptoms 1. However, be aware that the medial antebrachial cutaneous nerve may lie directly over the medial epicondyle and is at risk of direct injury from injections 7.

Surgical Intervention (After 3-6 Months of Failed Conservative Treatment)

For lateral epicondylitis:

• Surgical referral indicated if pain persists despite 3-6 months of well-managed conservative treatment 2
• Techniques include excision of abnormal tendon tissue and longitudinal tenotomies to release areas of scarring and fibrosis 2
• No single surgical technique (open, percutaneous, or arthroscopic) appears superior by any measure 8

For nerve entrapment with positive diagnostic block:

• Denervation of the lateral epicondyle by transection of posterior cutaneous nerve branches with implantation into triceps achieves good or excellent results in 80% of patients 6
• At mean 28 months follow-up, average pain score decreased from 7.9 to 1.9, and grip strength improved from 13 to 24 kg 6
• Immediate return to activities of daily living permitted without postoperative splinting 6

For ulnar nerve dislocation:

• Ulnar nerve anterior transposition surgery using subcutaneous transposition technique provides excellent results without pain 3

Critical Treatment Consideration

Radial nerve compression syndromes must be evaluated as a confounding source of symptoms and may require additional treatment in patients who fail to improve with denervation alone 6. The presence of radial tunnel syndrome should be noted but does not affect surgical candidacy for denervation 6.