32. Peripheral nerve lesion

Question 1

Causes

Answer 1

Trauma (blunt or penetrating) or acute compression
Dia., entrapment, vasculitis

Demyelination, axonal degeneration, or both.
- Depending on the severity and degree of nerve injury, recovery of remyelination and w/axonal regeneration and reinnervation of the sensory rcpts, motor end plates, or both.

Question 2

Symptoms

Answer 2

Demyelination & axonal degeneration => disruption of sensory function, motor function, or both in the injured nerve.
Injury to motor nerve => % mus. function
Injury to sensory nerve => % sensation to the affected nerve’s sensory distribution and/or neuromatous or causalgia pain

Weak., reduced reflexes
Sensory changes (numbness, paresthesias, tingling),
Mus.atrophy & fasciculations

Question 3

Diagnosis

Answer 3

MRI, CT, USG, electromyography

Motor assessment: Medical Research Council (MRC) 0-5 grading scale

Question 4

Treatment

Answer 4

• Closed nerve injury: If no recovery, clinically or w/electrodiagnostic studies, at 3 months after injury
• Open nerve injury (ie, laceration): All lacerations w/% sensation or motor weak.
• Crush nerve injury: After 3 months w/o reinnervation, surgical reconstruction w/nerve repair, transfer, or grafting is indicated