A 35-year-old woman presents with a 2-week history of progressive weakness of wrist and finger extension following a mid-shaft humeral fracture sustained in a fall. Examination reveals wrist drop, weakness of thumb extension, and sensory loss over the dorsal first web space. X-ray confirms a simple mid-shaft fracture with no displacement. What is the most appropriate next step in management?

Explanation

## Clinical Diagnosis This patient has a **radial nerve injury** secondary to a mid-shaft humeral fracture. The clinical triad is: - **Wrist drop** (loss of wrist extension via extensor carpi radialis longus/brevis). - **Weakness of thumb extension** (extensor pollicis longus). - **Sensory loss in the dorsal first web space** (radial nerve sensory branch). ## Mechanism of Injury The radial nerve is vulnerable to injury at the mid-shaft of the humerus because it runs in the **radial groove** on the posterior surface. Fracture fragments or callus formation can compress or stretch the nerve. ## Management Strategy **Key Point:** Most radial nerve injuries associated with **closed humeral fractures are neurapraxia or axonotmesis** (not complete transection). These have excellent prognosis for spontaneous recovery over 3–4 months. **High-Yield:** The correct approach is **conservative management with serial neurological assessment**: 1. **Serial clinical examination** at weekly intervals to document progression or recovery. 2. **EMG/NCS at 6–8 weeks** — this is the standard interval to detect denervation changes and confirm the severity of the lesion. 3. **Observation** — most radial nerve injuries recover spontaneously within 3–4 months without intervention. ## Why Not Immediate Surgery? | Reason | Explanation | |--------|-------------| | Fracture is non-displaced | No indication for ORIF on fracture grounds alone | | Nerve injury is likely neurapraxia | Conduction block; spontaneous recovery expected | | No clinical signs of transection | Wrist drop and sensory loss are consistent with compression, not division | | Early EMG (< 3 weeks) is non-diagnostic | Denervation potentials appear only after 3 weeks | **Clinical Pearl:** Radial nerve injury at the mid-shaft is the **most common nerve injury with humeral fracture** and has the **best prognosis** for spontaneous recovery (>90% recover without surgery). Contrast this with: - **Axillary nerve injury** (anterior shoulder dislocation) — also usually recovers spontaneously. - **Brachial plexus root avulsion** — no spontaneous recovery; requires early intervention. ## Timeline for Diagnostic and Therapeutic Decisions ```mermaid flowchart TD A[Mid-shaft humeral fracture + radial nerve injury]:::outcome --> B{Clinical signs of complete transection?}:::decision B -->|No| C[Conservative management: immobilization]:::action C --> D[Serial clinical exam weekly]:::action D --> E[EMG/NCS at 6-8 weeks]:::action E --> F{Evidence of denervation?}:::decision F -->|Mild-moderate| G[Continue observation, expect recovery by 3-4 months]:::action F -->|Severe/no recovery signs| H[Consider surgical exploration at 3-4 months]:::action B -->|Yes - complete transection| I[Urgent surgical exploration and repair]:::urgent ``` **Mnemonic:** **RADIAL = Recover After Delayed Interval with Active Limb management** — i.e., time and serial exam are the management tools, not immediate surgery.