Terms

Question 1

define/ describe neurotmesis

Answer 1

classifies nerve injury - 3RD TYPE. of nerve injury
most serious nerve injury in the scheme
nerve. nerve sheat are damaged

Disruption of the axon, myelin sheath and surrounding connective tissue.
Wallerian degeneration occurs.

Question 2

There are 3 types of nerve injury:

Answer 2

Neuropraxia
Axonotmesis
Neurotmesis

Neuropraxia

• Nerve intact but electrical conduction is affected
• Full recovery
a) Prognosis is good == so complete recovery
b) No degeneration, no loss in continuity

• Autonomic function preserved
• Wallerian degeneration does not occur

Axonotmesis

• Axon is damaged and the myelin sheath is preserved
• . The connective tissue framework is not affected.
• Wallerian degeneration occurs.
a) Demyelination and axon loss
b) Wallerian degeneration – nerve fiber is cut and the axon distal to the injury degenreates

Neurotmesis

• Disruption of the axon, myelin sheath and surrounding connective tissue.
• Wallerian degeneration occurs.
a) isconnection of a nerve
i)
b) Axonal loss + degeneration + endometirum is lost (so the outer red part is broken) == no recovery

Nerve intact but electrical conduction is affected
Full recovery
Autonomic function preserved
Wallerian degeneration does not occur
Axonotmesis
Axon is damaged and the myelin sheath is preserved. The connective tissue framework is not affected.
Wallerian degeneration occurs.
Neurotmesis
Disruption of the axon, myelin sheath and surrounding connective tissue.
Wallerian degeneration occurs.

Question 3

Wallerian Degeneration

Answer 3

Axonal degeneration distal to the site of injury.
Typically begins 24-36 hours following injury.
Axons are excitable prior to degeneration occurring.
Myelin sheath degenerates and is phagocytosed by tissue macrophages.

Question 4

Nerve repair

Answer 4

Neuronal repair may only occur physiologically where nerves are in direct contact.

Where a large defect is present, the process of nerve regeneration is hampered. It may not occur at all or result in the formation of a neuroma. Where nerve regrowth occurs it is typically at a rate of 1mm per day.

Question 5

Clinical test for nerve regeneration

Answer 5

Light percussion on the nerve with a clinical hammer, from distal to the proximal end

A tingling sensation is experienced at the level of regeneration

As the regeneration of the axon advances, the level of tingling sensation also shifts  point can migrate as it gets worse- so can be used as a follow up as well