Table 1.

Sunderland nerve injury classification with corresponding surgical findings, MRN findings, and surgical indications

Sunderland Injury ClassificationMRN FindingsRecovery PotentialSurgery IndicationSurgical Findings
IHomogeneous increased T2 signal of nerve with no change in caliber, usually resolve short of surgeryFullNoneIntact with no internal or external fibrosis, normal neuroarchitecture
IIHomogeneous increased T2 signal of nerve and mild to moderate nerve thickening, less than 100% thickening than the adjacent or contralateral nerveFullNone unless persistent pain for >3 monthsIntact with no internal fibrosis, with external fibrosis, restricted mobility with intact neuroarchitecture
IIIHomogeneous increased T2 signal of nerve and moderate-marked nerve thickening, more than 100% thickening than the adjacent or contralateral nerveSlow/incompleteNone or neurolysisIntact with internal and external fibrosis, restricted mobility, and disturbed neuroarchitecture
IVHeterogeneous increased T2 signal of nerve and focal enlargement consistent with a neuroma-in-continuity in an otherwise continuous nervePoor to noneNerve repair, graft, or transferPartial transected nerve, some amount of distal nerve with or without lateral neuroma
VDiscontinuous nerve with end bulb neuroma and a complete nerve gapNoneNerve repair, graft, or transferCompletely transected nerve