Peripheral Nerves

Question 1

Seddon’s classification

Answer 1

Class I - Neuropraxia
Class II - Axonotmesis
Class III - Neurotmesis

Question 2

Neuropraxia

Answer 2

Temporary interruption of conduction without loss of axonal continuity
Physiologic block of nerve conduction in the affected axons
Sensory-motor problems distal to the site of injury
The endoneurium, perineurium, and the epineurium are intact
Conduction is intact in the distal segment and proximal segment, but no conduction occurs across the area of injury
Recovery of nerve conduction deficit is full, and requires days to weeks

Question 3

Axonotmesis

Answer 3

Loss of the relative continuity of the axon and its covering of myelin, but preservation of the connective tissue framework of the nerve (the encapsulating tissue, the epineurium and perineurium, are preserved)
There are sensory and motor deficits distal to the site of lesion
There is no nerve conduction distal to the site of injury (3 to 4 days after injury)
Axonal regeneration occurs and recovery is possible without surgical treatment - sometimes surgical intervention because of scar tissue formation is required

Question 4

Neurotmesis

Answer 4

Total severance or disruption of the entire nerve fibre
There is connective tissue lesion that may be partial or complete
Sensory-motor problems and autonomic function defect are severe
There is no nerve conduction distal to the site of injury (3 to 4 days after lesion)
Because of lack of nerve, surgical intervention is necessary