Peripheral Nerve Injury Fundamentals
A practical framework for localising nerve injury, documenting function and understanding timing of recovery and reconstruction.
Learning objectives
- Localise median, ulnar and radial nerve dysfunction clinically.
- Differentiate compression, neurapraxia and possible transection in the initial assessment.
- Document motor and sensory baselines reproducibly.
- Understand why timing, distance to target muscle and mechanism affect reconstruction.
Localise before labelling
Describe the pattern of motor and sensory loss rather than writing only ‘nerve injury’. Median, ulnar and radial deficits produce different combinations of weakness and sensory change depending on lesion level.
Mechanism predicts biology
Compression, stretch, crush and sharp laceration have different probabilities of spontaneous recovery. A clean transection behaves differently from neurapraxia after transient compression.
Document motor function
Use specific muscles and graded strength rather than generic grip strength alone. Thenar abduction, finger abduction/adduction and wrist/finger extension can help localise major nerve dysfunction.
Document sensation
Map the affected territory and use a reproducible method. Two-point discrimination, monofilament testing or other quantitative tools can be helpful in follow-up when used consistently.
Electrodiagnostic studies
Nerve-conduction studies and EMG can help localise lesions and assess axonal loss, but timing matters because denervation changes evolve after injury.
Reconstruction principles
When recovery is not expected, options may include direct repair, grafting, nerve transfer or tendon transfer. The distance to motor end plates and time since denervation are crucial in motor reconstruction.
Case checkpoint
A patient has an open forearm laceration with inability to abduct the index finger and numbness of the little finger. Document intrinsic motor function and ulnar sensory loss precisely; in an open sharp injury, direct inspection may be more informative than waiting for late electrodiagnostic changes.
Self-assessment
Q1. Why is ‘weak grip’ insufficient documentation?
Grip depends on many muscles and nerves. Specific motor testing localises the lesion and creates a reproducible baseline.
Q2. Does every nerve deficit require immediate nerve conduction testing?
No. Timing and mechanism matter, and early studies may not yet show the full extent of axonal injury.
Q3. What makes motor recovery time-sensitive?
Prolonged denervation leads to motor end-plate and muscle changes, so regeneration distance and delay influence reconstructive options.
Q4. Name two reconstructive options beyond direct repair.
Nerve grafting, nerve transfer and tendon transfer are examples.
Q5. Why map sensation?
A mapped baseline allows localisation and objective comparison during recovery.
Finished this module?
Save completion on this device. This is a learning-progress marker only and is not an accredited CME credit.