Types of nerve injuries
Peripheral nerve injuries are classified by severity using the Seddon and Sunderland classifications. Neurapraxia involves temporary conduction block without axonal degeneration � full recovery occurs within weeks to months. Axonotmesis involves axonal degeneration with intact connective tissue framework � recovery occurs over months at approximately 1 mm/day regeneration rate. Neurotmesis involves complete nerve transection with disruption of connective tissue � surgical repair is typically required for meaningful recovery.
Common mechanisms include laceration (sharp objects, glass, knives), compression (prolonged pressure, casts, tourniquets), stretch/traction injuries (dislocations, fractures), and thermal injury (burns, electrical injury). Timing of evaluation is critical � early assessment (within days to weeks) allows optimal treatment planning, while delayed evaluation (months after injury) may result in irreversible muscle atrophy.
- Neurapraxia � conduction block, recovers in weeks
- Axonotmesis � axonal degeneration, regenerates at 1mm/day
- Neurotmesis � complete transection, requires surgical repair
- Laceration, compression, stretch, and thermal mechanisms
Related: Neuropathy Treatment → · Dr. Jitendra Knowledge Hub → · ICHD-3 Topic →
Evaluation and treatment approach
Clinical evaluation characterises the injury pattern: motor weakness, sensory loss, distribution relative to known nerve anatomy, and timing relative to the injury event. Nerve conduction studies (NCS) and electromyography (EMG) performed 3-4 weeks after injury distinguish neurapraxia from axonotmesis/neurotmesis, quantify severity, and identify whether reinnervation is occurring. Early NCS (within 1 week) may show conduction block but cannot yet detect Wallerian degeneration.
Treatment depends on injury severity and timing. Neurapraxia and mild axonotmesia are managed conservatively with observation, physiotherapy, and protective splinting. Complete transection (neurotmesis) or severe axonotmesia without early recovery warrants surgical exploration and repair. Referral to peripheral nerve surgery occurs when indicated. Dr. Jitendra Prasad Yadav (NMC 8029) provides NCS/EMG interpretation and treatment planning at Kathmandu Neurology Clinic, Durbar Marg, Opposite of Yak & Yeti Hotel.
| Injury Type | NCS/EMG Findings | Treatment |
|---|---|---|
| Neurapraxia | Conduction block, normal distal CMAP | Conservative, full recovery expected |
| Axonotmesia | Reduced CMAP amplitude, fibrillation potentials | Conservative if mild, surgery if severe |
| Neurotmesis | No response distal to injury | Surgical repair required |