Sunderland nerve injury classification with corresponding surgical findings, MRN findings, and surgical indications
| Sunderland Injury Classification | MRN Findings | Recovery Potential | Surgery Indication | Surgical Findings |
|---|---|---|---|---|
| I | Homogeneous increased T2 signal of nerve with no change in caliber, usually resolve short of surgery | Full | None | Intact with no internal or external fibrosis, normal neuroarchitecture |
| II | Homogeneous increased T2 signal of nerve and mild to moderate nerve thickening, less than 100% thickening than the adjacent or contralateral nerve | Full | None unless persistent pain for >3 months | Intact with no internal fibrosis, with external fibrosis, restricted mobility with intact neuroarchitecture |
| III | Homogeneous increased T2 signal of nerve and moderate-marked nerve thickening, more than 100% thickening than the adjacent or contralateral nerve | Slow/incomplete | None or neurolysis | Intact with internal and external fibrosis, restricted mobility, and disturbed neuroarchitecture |
| IV | Heterogeneous increased T2 signal of nerve and focal enlargement consistent with a neuroma-in-continuity in an otherwise continuous nerve | Poor to none | Nerve repair, graft, or transfer | Partial transected nerve, some amount of distal nerve with or without lateral neuroma |
| V | Discontinuous nerve with end bulb neuroma and a complete nerve gap | None | Nerve repair, graft, or transfer | Completely transected nerve |