Peripheral Nerve Injuries

Question 1

Structure of peripheral nerve?

Answer 1

Axons in endoneurium –> fascicles in perineurium –> nerve in epineurium

Question 2

Types of nerve injury?

Answer 2

Trauma (direct or indirect)

Compression

Question 3

Neurapraxia

Answer 3

Nerve in continuity
stretched or bruised
reversible conduction block (local ischaemia and demyelination)
Prognosis good

Question 4

Axonotmesis

Answer 4

Endoneurium intact but disruption of axons
Stretched or crushed or direct blow
Wallerian degeneration follows
Prognosis fair (sensory recovery better than motor)

Question 5

Neurotmesis

Answer 5

Complete nerve division
Laceration or avulsion
No recovery unless repaired
Endoneural tubes disrupted (high chance miswiring)
Poor prognosis

Question 6

Closed nerve injuries

Answer 6

Nerve injuries in continuity
Spontaneous recovery possible
Surgery indicated after 3m if no recovery identified

Question 7

Clinical features of injury sesonsry?

Answer 7

Dysaethesia
Anasthesia, Hypo and hyper aesthetic
Paraesthetic

Question 8

Clinical features of injury motor?

Answer 8

Paresis or paralysis +/- wasting

Dry skin

Question 9

Clinical features of injury - reflexes?

Answer 9

Diminished or absent

Question 10

Nerve injury healing

Answer 10

Slow
Initial death of axons distal to site of injury
Proximal axonal budding after about 4 days
Pain returns first

Question 11

How do you monitor nerve injury healing

Answer 11

Tinels sign

Nerve conduction studies

Question 12

Rule of three

Answer 12

Immediate within 3 days for clean and sharp injuries
Early within 3 weeks for blunt/contusion injuries
Delayed surgery, 3 months after for closed injuries

Question 13

Findings of an UMN lesions

Answer 13

Decreased strength
Increased tone, reflexes
Present clonus and Baninski’s sign
No atrophy

Question 14

Findings of LMN lesions

Answer 14

Decreased strength, tone and reflexes
Absent clonus and babinski’s sign
Atrophy present