Nerve Injury Flashcards
How would u assess nerve injury
- Identify areas affected
- Ask for symptoms. Duration. Any improvement?
- Nerve assessment
Mechanoreceptors:
- Brush stroke
- 2 point discrimination
- Light touch with vonFrey fibers
- Pressure
Nociceptors:
- Pinprick
- Thermal with heated gp, cold ethyl chloride
Classification of nerve injury (seddon and sunderland)
Seddon
Neuropraxia
Axonotmesis
Neurometsis
Sunderland
I - neuropraxia - conduction block - TIA/intraneuronal edema - nerve sheath intact - no Wallerian degeneration
II - axonometsis - axonal injury - traction or compression - nerve sheath intact - wallerian degeneration distal to injury
III - axonometsis - endoneural injury with loss of continuity - moderate traction, crush - peri and epineurium intact - wallerian degeneration
IV - axonotmesis - endoneural & perineural injury - severe traction or crush - epineurium intact - wallerian degeneration
V - neurotmesis - epineural, perineural, endoneural injusty - comple transection
incidence of nerve injury in maxilla Ogs at 6/12
10-15%
Whats the incidence of nerve injury with persistent neurosensory disturbance 6/12 after mandibular orthognathic surgery
Generally - 35%
SSO - 60% IVRO - <10% Ant mandible - 30% SSO + Ant mandible 50% IVRO + Ant mandible 30%
incidence of permanent NSD after mandibular ogs
After 2 years, 20-40% will have NSD
Indications of microsurgery nerve repair
- Clinically observed nerve transection
- Presence of foreign body
- Progressive worsening symptoms
- Profound hypoesthesia that doesnt resolve
Contraindications of microsurgery
- Elderly
- Medically compromised patients
- Centrally mediated pain
- Too long delayed since injury
- Improving symptoms
- Symptoms tolerable to patient
Techniques of microsurgery nerve repair
- External neurolysis
- Internal neurolysis
- Excision of neuroma/ fibrosis with resection of nerve in 1mm increment until healthy nerve seen
Other treatments of nerve injury
- Primary nerve anastomosis
- in completely transected nerve
- tension free
- loss of structure minimal - Neurorraphy - epineural repair with minimal number of sutures
- Autogenous nerve grafting - sural or great auricular nerve
- Microsurgical repair with processed nerve graft
- Entubulation - recreating a conduit to allow nerve regrowth within the conduit
Whats the max gap for anastomosis for lingual and ID nerve
Lingual 10mm
ID 5mm
What are options of nerve grafting
- Sural nerve
2. Great auricular nerve
What are calibers of IAN?
Diameter 2.5mm
Cross section Round
Fascicular 15-18
Caliber of Lingual nerve
Diameter 3mm
Cross section Round
Fascicular pattern 15-20
Calibers of autogenous neural grafts
Sural - 2mm, flat, 10-12 fascicles, 20cm harvest - will cause lateral foot/heel numbness
Great auricular nerve - 1.5mm, oval, 8-10 fascicles, 1-2cm harvest - will cause numbness ovet lateral neck, posterior mandible, ear
If ptn is about to undergo nerve repair, whats ur advice prior to surgery
Possible outcomes
- Increased sensory loss or worsening neuropathic pain
- Minimal to no improvement
- Acceptable improvement
- Return to normal or nearly normal
Scar if require submandibular approach
- to be advise regarding the tx of scar postop (cosmetically skin closure, steroid injection)
Harvesting a neural autograft
- cause anaesthesia/paraesthesia at region of distribution of nerve.
GAN - near the angle of mandible and earlobe.
SN - lateral foot and heel
- neuropathic pain dt neuroma formation (prevented by redirecting nerve to nearby muslce or epineural capping)
