How is trauma to nerves classified?
Laceration, stretch, compression, or drug toxicity can all cause trauma to a nerve. Seddon’s classification grades the severity of a nerve injury. Neurapraxia (class I) describes temporary interruption of conduction spontaneously recovering in days to weeks, whereas axonotmesis (class II) involves the loss of continuity of an axon and myelin, while the epineurium and perineurium framework are preserved. Surgical intervention is sometimes needed. Lastly, neurotmesis (class III) involves total disruption of the nerve fiber, and surgical intervention is required. Sunderland’s classification is similar, with first degree and second degree referring to neurapraxia and axonotmesis, respectively, and third through fifth degree being further divisions of neurotmesis.