peripheral nerve injury Surgery for Peripheral Nerve

Peripheral Nerve Injury
Neurosurgeon
Yoon Seung-Hwan


Anatomy
• Connective tissue

- major tissue componant
- epineurium, perineurium, endoneurium
• Nerve tissue

- axon, schwann cell



Peripheral Nerve Injury
• Acute injury
• Chronic injury
(entrapment neuropathy)


Classification


Neuropraxia
• the mildest form, reversible conduction
block
• loss of function, which persists for hours
or days
• direct mechanical compression, ischemia,

mild burn trauma or stretch


Axontmetic
• axon continuity is disrupted
• fascicular integrity is maintained
• Wallerian degeneration occurs


Neurotmesis
• laceration from sharp or blunt forces
• the only important consideration is
the timing of repair
• acute repair or more bluntly lacerated
nerves are repaired 3-4 weeks


Factor s for Decision Making
• Age
• Segment between injury and end organ
• Gap of injury
• Mechanism of injury
• Severity of injury
• Presence of pain


Axonal Regeneration
• Initial delay
to the distal stump : 1-2 week delay
• Growth rate

1mm/day, 1 inch/month
• Terminal delay
several weeks-several months
Recovery within 6 weeks good prognosis


Acute Denervation

Fibrillation potentials and
positive sharp waves


Regeneration

Long duration, small amplitude
polyphasic motor unit potentials


Diagnosis
Clinical Signs
• Motor function
• Tinel’s sign
positive-sensory function
negative(after 4-6weeks)-total interruption
• Sweating-sympathetic fiber
• Sensory function


Tinel’s sign
• advancing along the anatomical

distribution of the nerve, particularly if it
is does so at the expected rate of nerve
regeneration, then this provides evidence
of ongoing regeneration.


Diagnosis
Electrophysiological Tests
• EMG
• SNAP
• SSEP
• Intraoperative NAP


EMG

SNAP


SSEP


Intraoperative NAP


Muscle Atrophy
• 24 month rule
- 2 년 년년 년년 년 muscle scar tissue 년 년년년년 년년
년년년년 ) 년년년년
• Muscle atrophy

start : post-injury 1 month
peak : 3rd - 4th month
• Segment between injury and end organ

년 (년


Treatment
Time of Operation
• Open injury
Early intervention
Delayed intervention
• Closed injury
Delayed intervention


Early Intervention
• Enlarging hematoma/aneurysmal sac
• Predisposing to Volkmann’s ischemic
contracture
• Severe noncausalsic pain SD
• Injury to N. in areas of potential entrapment
• Simple, clean lacerating injury


Delayed Intervention
• 2-3 months after injury
• No clinical or substantial recovery
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Operations
• Neurolysis : internal/external
• Nerve repair
end-to-end repair : epineural/fascicular
autologous graft : sural N.
• Neurotization
intercostal N./accessory N./cervical plexus
within 1 year
• Muscle and tendon transfer


Epineural Repair


Fascicular Repair