Sunderland Classification

Grade

Description

1

Neurapraxia or physiological conduction block, in which the nerve has lost its conduction function. There are no anatomical changes.

2

Axonotmesis with intact endoneurium.

3

Axonotmesis with interrupted endoneurium (axonal lesion with degeneration of the distal segments). Perineurium and the basal lamina of the Schwann cells are intact.

4

Here, the perineurium is additionally interrupted. The internal nerve structure is destroyed and the fascicular structure has been lost or converted into scar tissue. Continuity is maintained only by the inter- and epifascicular epineurium, which itself is fibrosed by the trauma.

5

Here, the epineurial continuity is additionally interrupted (Neurotmesis with discontinuity of the nerve due to clean transection or tearing of the nerve).