How should I evaluate and manage an adult with acute radial nerve palsy presenting with sudden weakness of wrist and finger extension, loss of thumb abduction, and sensory loss over the dorsal hand and first web space?

Radial Nerve Palsy: Evaluation and Management

Initial Clinical Assessment

For acute radial nerve palsy in adults, immediately determine the mechanism of injury and perform a focused neuromuscular examination to guide urgent versus expectant management, as the energy of trauma is the single most important prognostic factor.

Key History Elements

• Mechanism of injury: Distinguish between low-energy (simple fall) versus high-energy trauma (motor vehicle collision, crush injury), as this fundamentally determines prognosis and management strategy 1
• Timing of onset: Primary palsy (immediate) versus secondary palsy (delayed after fracture treatment) 2
• Associated injuries: Humeral shaft fracture is present in the majority of cases, with radial nerve palsy occurring in approximately 12.3% of humeral fractures 3

Physical Examination Specifics

• Motor testing: Assess wrist extension (extensor carpi radialis/ulnaris), finger extension at MCP joints (extensor digitorum communis), thumb extension and abduction (extensor pollicis longus/brevis, abductor pollicis longus) 2
• Sensory examination: Test sensation over the dorsal first web space and dorsal hand 2
• Document severity: Complete versus partial palsy, as partial palsies have better prognosis 1

Diagnostic Workup

Imaging

• Plain radiographs: Obtain AP and lateral views of the humerus to identify fracture pattern (spiral fractures carry highest risk at 57.1% of nerve injuries) 4
• Ultrasound: Consider early ultrasonography to assess nerve continuity and severity of damage, particularly in high-energy trauma 2
• Electrodiagnostic studies: Obtain baseline EMG/NCS at 3-4 weeks post-injury to document severity and guide surgical timing 2

Management Algorithm

Low-Energy Trauma (Simple Falls, Isolated Fractures)

Expectant management is the standard of care for low-energy radial nerve palsies, as spontaneous recovery occurs in essentially 100% of cases 1, 5

• Initial treatment: Fracture stabilization (splinting or surgical fixation based on fracture characteristics) with nerve observation 5
• Monitoring protocol: Clinical examination every 2-4 weeks looking for signs of recovery (Tinel's sign progression, return of proximal muscle function) 2
• Expected recovery timeline: Initial signs appear at mean 3.2 weeks (range 1-8 weeks), with full recovery by 14 weeks on average 1
• Surgical exploration: Only indicated if no clinical or electrodiagnostic evidence of recovery by 3-4 months 5

High-Energy Trauma (MVA, Crush Injuries, Open Fractures)

Early surgical exploration within 3 weeks significantly improves recovery rates (89.8% vs 68.1% with delayed surgery) and should be strongly considered in high-energy mechanisms 3

• Immediate exploration indications 2, 1:

  • Open fractures with nerve exposure
  • Vascular injury requiring repair
  • Ultrasonography showing complete nerve transection
  • Fracture requiring open reduction and internal fixation

• Intraoperative findings and management 1:

  • Intact or entrapped nerve: Neurolysis and release, excellent prognosis
  • Severe contusion/neurotmesis: Primary repair if possible, nerve grafting if gap >2-3 cm
  • Expected recovery: Mean 12 weeks for initial signs (range 3-23 weeks), full recovery by 26 weeks if nerve intact 1

Surgical Options for Failed Recovery

The timing of intervention determines the surgical approach, with nerve transfers offering superior results to tendon transfers when performed within the appropriate window 2

Nerve Reconstruction (Before 6 Months)

• Autograft: Gold standard for younger patients with suitable local conditions and nerve gap requiring bridging 2
• Nerve transfers: Performed by experienced microsurgeons, effective up to 10 months post-injury with satisfactory functional outcomes 2
• Indications: Age <50 years, no signs of recovery by 3-6 months, electrodiagnostic confirmation of severe axonal loss 2

Tendon Transfers (After 10-12 Months)

• Standard treatment: Reliable and fast results when nerve recovery has definitively failed 2
• Common procedures: Pronator teres to extensor carpi radialis brevis (wrist extension), flexor carpi radialis to extensor digitorum communis (finger extension), palmaris longus to extensor pollicis longus (thumb extension) 2
• Advantages: Immediate functional improvement, no waiting for reinnervation 2

Critical Prognostic Factors

Poor Prognosis Indicators

• High-energy trauma mechanism: 8 of 13 patients (61.5%) with high-energy injuries had severely damaged nerves that failed to recover despite microsurgical reconstruction 1
• Complete motor and sensory loss: Suggests neurotmesis rather than neurapraxia 1
• Delayed fracture healing: Average 18.7 weeks in high-energy trauma versus 10.4 weeks in low-energy, indicating severe soft tissue injury 1
• No recovery signs by 6 months: Approximately 23% of conservatively managed patients fail to recover spontaneously 3

Favorable Prognosis Indicators

• Low-energy mechanism: 100% recovery rate in simple fractures 1, 5
• Early return of proximal function: Suggests neurapraxia with intact axons 2
• Partial palsy at presentation: Better outcomes than complete palsy 1

Common Pitfalls to Avoid

• Assuming all radial nerve palsies recover spontaneously: This is only true for low-energy trauma; high-energy mechanisms have 61.5% risk of permanent injury requiring reconstruction 1
• Delaying exploration beyond 3 weeks in high-energy trauma: Early exploration (within 3 weeks) achieves 89.8% recovery versus 68.1% with delayed surgery 3
• Waiting too long for nerve transfers: Nerve transfers are only effective up to 10 months; beyond this window, only tendon transfers remain viable 2
• Failing to obtain baseline electrodiagnostics: EMG/NCS at 3-4 weeks provides objective documentation of injury severity and guides surgical timing 2