Table 1 Seddon's and Sunderland's classifications of nerve injuries
Injury | Pathophysiology | Exam Findings | Nerve Studies | Prognosis |
|---|---|---|---|---|
Neurapraxia (Seddon) First Degree (Sunderland) | Reversible conduction block. Local compression with ischemia; selective demyelination of the axon sheath possible. | Motor paralysis: complete Muscle atrophy: minimal Sensory alteration: minimal, often with sparing | Distal nerve conduction: present. Motor unit action potential: absent. Fibrillation: occasionally detectable. | Good prognosis. Full recovery usually within days to 2–3 weeks |
Axonotmesis (Seddon) Second Degree (Sunderland) | More severe injury with disruption of the axon and myelin sheath. | Motor paralysis: complete Muscle atrophy: progressive Sensory alteration: complete | Distal nerve conduction: absent. Motor unit action potential: absent. Fibrillation: present. | Fair prognosis. Full recovery possible without surgery; recovery at 1 mm/day |
Third Degree (Sunderland) | Endoneurium disrupted; epineurium and perineurium intact. | Same | Same | Same |
Fourth Degree (Sunderland) | Endoneurium and perineurium disrupted; epineurium intact. | Same | Same | Same |
Neurotmesis (Seddon) Fifth Degree (Sunderland) | Complete nerve division with disruption of the endoneurium, perineurium, and epineurium. | Same | Same | Poor prognosis. Requires surgery with varying degrees of impairment present even after surgery |