What is the classification of nerve injuries and what are the typical findings?
Seddon was the first to classify nerve injuries into three categories based on the presence of demyelination and the extent of damage to the axons and other connective tissues. This classification was expanded by Sunderland. The mildest form of damage, neurapraxia, can occur from mild compression or from mild traction to the nerve. This can result in conduction slowing and “gain of function” symptoms. If the compression continues or the traction injury is more severe, axonotmesis may occur. This will result in “loss of function” symptoms. If the injury is severe enough, neurotmesis may occur.
| Seddon | Sunderland | Findings |
|---|---|---|
| Neurapraxia | Grade I | Focal, segmental demyelination resulting in conduction slowing |
| Axonotmesis | Grade II | Axon is damaged, but endoneurium is intact |
| Axonotmesis | Grade III | Axon and endoneurium are damaged, but epineurium is intact |
| Axonotmesis | Grade IV | Axon, endoneurium, and epineurium are damaged, but the epineurium is intact |
| Neurotmesis | Grade V | The nerve is transecte |
