Seddon's and Sunderland's Classification of Nerve Injury

Neuropraxia (Sunderland 1°)

Segmental demyelination

Leads to slowed or blocked action potential at point of demyelination; normal above

Results in mild ischemia from nerve compression or traction

What are these symptoms of?

Pain, no or minimal muscle wasting, muscle weakness, numbness, proprioception affected and takes minutes to days to recover

Neuropraxia (Sunderland 1°)

Axonotmesis (Sunderland 2° and 3°)

Loss of axonal continuity but the connective tissue covering remains intact

Wallerian degeneration distal to lesion

Results of prolonged compression or stretch causing infarction and necrosis

Walleran degeneration

Active biological process where the part of a nerve fiber (axon) distal breaks down and disintegrates after the nerve is cut, crushed, or damaged.

PNS: schwann cells help to guide new growth once debris is cleared — better prognosis

CNS: glial scars replace the tract and regrowth is inhibited

What are these symptoms of?

Pain, evident muscle wasting, complete motor / sensory / sympathetic functions lost, sensation is restored before motor function, axons regenerate 1in/month, 1mm/day so likely takes months to recover

Axonotmesis (Sunderland 2° and 3°)

Neurotmesis (Sunderland 3°, 4° and 5°)

Complete severance of nerve fiber with disruption of connective tissue coverings

Wallerian degeneration distal to lesion

Result of a ballistic or stab wounds, avulsion, rupture

what are these symptoms of?

No pain (anesthesia), muscle wasting, complete motor, sensory and sympathetic functions lost, takes months to recover and only with surgery

Neurotmesis (Sunderland 3°, 4° and 5°)