What are the symptoms and management of radial neuropathy?

Radial Neuropathy: Symptoms and Management

Clinical Presentation

Radial neuropathy presents primarily with motor weakness, most characteristically as wrist drop, with sensory symptoms being less prominent than in other upper extremity neuropathies. 1

Motor Symptoms

• Wrist drop is the hallmark clinical feature, resulting from loss of wrist extensor function when the nerve is injured distal to triceps innervation 1, 2
• Finger drop occurs with weakness of finger extensors, particularly affecting the metacarpophalangeal joints 3
• Triceps weakness only occurs with very proximal lesions in the upper arm; its presence helps localize the injury site 4
• Partial wrist drop may occur with posterior interosseous nerve (PIN) involvement, as the extensor carpi radialis longus (innervated more proximally) remains functional 3

Sensory Symptoms

• Numbness affecting the dorsolateral aspect of the hand 2
• Sensory loss over the dorsal aspect of the radial three-and-a-half digits (thumb, index, middle, and radial half of ring finger) 2
• Decreased sensation in the first web space between thumb and index finger 2
• Paresthesias including tingling in the affected distribution 5, 6

Key Anatomical Distinction

Posterior interosseous neuropathy (PIN) causes finger drop and partial wrist drop WITHOUT sensory loss, as the PIN is purely motor. 3 This distinguishes it from more proximal radial nerve lesions that affect both motor and sensory function.

Common Etiologies

• Trauma is the most common cause, including humeral shaft fractures (most frequent site of main radial nerve injury) 1, 2
• Compression from prolonged pressure in the spiral groove of the humerus against hard surfaces (e.g., "Saturday night palsy") 5
• Surgical injury during procedures 4
• Entrapment at the arcade of Frohse or leash of Henry in the proximal forearm (affecting PIN) 3

Risk Factors

• Diabetes mellitus 6
• Smoking 6
• Alcohol consumption 6
• Rheumatoid arthritis 6
• Hypothyroidism 6

Diagnostic Approach

Clinical Examination

• Assess wrist extension strength with the forearm pronated to isolate radial nerve function 4
• Test finger extension at the metacarpophalangeal joints 3
• Evaluate triceps function to determine if the lesion is proximal or distal to the spiral groove 4
• Map sensory loss in the first web space and dorsal hand 2

Electrodiagnostic Studies

• Nerve conduction studies and electromyography (EMG) confirm the diagnosis, localize the lesion precisely, and help determine prognosis 1, 4
• These studies distinguish radial neuropathy from cervical radiculopathy (C7) or other conditions causing wrist drop 4

Imaging

• Plain radiographs identify fractures, callus formation, or bony tumors causing compression 2
• Ultrasound allows direct visualization of the nerve, assessment of exact injury site, altered echogenicity, focal thickening, and identification of compressive lesions 2
• MRI/MR neurography provides superior soft-tissue detail, characterizes lesions, and is increasingly important when trauma history is absent 1, 2

Management Algorithm

Conservative Management (First-Line)

Most traumatic radial neuropathies have good prognosis for spontaneous recovery and should be managed conservatively initially. 1

• Wrist splinting in extension to prevent contractures and maintain hand function during recovery 1
• Physical therapy focusing on range of motion exercises and preventing joint stiffness 1
• Observation period of 3-6 months for evidence of recovery, as many traumatic lesions recover spontaneously 1

Surgical Intervention

Surgical exploration is indicated when:

• No clinical or electrodiagnostic evidence of recovery after 3-6 months of conservative management 3
• Imaging identifies a compressive lesion (tumor, callus, entrapment) 2, 3
• Complete nerve transection is suspected 1

Surgical options include:

• Nerve decompression at sites of entrapment (arcade of Frohse, leash of Henry) 3
• Tendon transfers for salvage reconstruction when severe axonal loss makes functional reinnervation unlikely 3
• Nerve repair or grafting for transection injuries 1

Critical Pitfalls to Avoid

• Do not assume all wrist drops are radial neuropathy—cervical radiculopathy (C7) can mimic this presentation and requires different management 4
• Recognize that PIN lesions spare sensation entirely—presence of sensory loss indicates a more proximal lesion 3
• Avoid delaying imaging in non-traumatic cases—compressive lesions require identification and may need surgical decompression 1, 2
• Do not overlook bilateral symptoms—these suggest systemic causes (diabetes, hypothyroidism) rather than focal nerve injury 6

Prognosis

Traumatic radial neuropathies generally have favorable prognosis for recovery, with most patients regaining substantial function. 1 However, patients with persistent deficits benefit from rehabilitation techniques and surgical reconstruction to optimize functional outcomes 1.