Tissue disruption follows a hierarchical cascade (from Axon up to Epineurium). Lower layers cannot be intact if higher layers are severed.
Nerve Severity Grade
Grade I
Neuropraxia
Spontaneous Prognosis
"Conduction block without structural disruption. Full recovery expected in hours to several weeks."
High-Fidelity Sunderland Audit.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Classifying penetrating or crush trauma to peripheral nerves.
Deciding exactly when a nerve injury warrants surgical exploration (Grade 4/5) vs expectant waiting (Grade 1/2).
Section 2
Literature
Development
Sir Sydney Sunderland expanded on Seddon's original 3-tier classification (Neuropraxia, Axonotmesis, Neurotmesis) in 1951. He realized that "Axonotmesis" wasn't detailed enough. If an axon breaks but its internal tunnel (endoneurium) is intact, it heals perfectly (Sunderland II). But if the tunnel is broken (Sunderland III/IV), the axon gets lost regenerating, causing a painful neuromatous tangle of crossed wiring.
Section 3
Pearls/Pitfalls
The Neuroma-in-Continuity
Grade IV injuries are clinically devastating. The nerve looks completely intact from the outside (because the Epineurium is intact), tricking untrained surgeons into leaving it alone. But inside, it is completely scarred over (neuroma-in-continuity). If an intact-looking nerve fails to conduct EMGs after 3-4 months, it is a Grade IV and the scarred segment must be surgically resected and grafted.
Section 4
Evidence Appraisal
Primary Reference
A classification of peripheral nerve injuries producing loss of function
