Nerve Injury

Question 1

Nerve Injury - Dentoalveolar IAN and Lingual nerve injury percentage and papers

Answer 1

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• • Pichler 2001
    
    • 8x more likely for lingual nerve injury with retraction
    • Lingual retraction was not protective for permanant nerve injury
    • 6.4% - Lingual retraction (Temp + Permanant)
    • 0.6% - Lingual retraction (Permanant)
    • 0.6% No lingual retraction (Temp + Permanant)
    • 0.2% - No lingual retraction (Permanant)

Question 2

Nerve Injury - Orthognathics IAN, Lingual and Infraorbital nerve injury percentages and papers

Answer 2

Mensink 2012 IAN - 90% - Temporary - 10% - BSSO only - 30% - BSSO + Genio Jacks 1998 Lingual - 20% Temporary - 5% Permanant Bays 2003 Infraorbital - 6% - Permanant

Question 3

Nerve Injury - Sensory Nerve Classification

Answer 3

Seddon - Neuropraxia - Injury to nerve conduction without disruption in its structure - Axonotmesis - Injury to one or more axons within nerve bundle - Neurotmesis - Disruption of the entire nere Sunderland - 1 - Neuropraxia - 2 - Axon only - 3 - Endoneurium - 4 - Perineurium - 5 - Epineurium British Medical Council Classification Medical reseach council scale S3 and above considered success by Bagheri S0 - No sensation S1 - Deep pain only S2 - Pain and some touch S2+ - Pain and touch with hyperaesthesia S3 - Pain and touch without dysaesthesia, 2 point >15mm S3+ - 2 point 7-15mm S4 - 2 point 2-6mm (Normal 4mm)

Question 4

Nerve Injury - Motor Nerve Classification

Answer 4

House Brackmann Assesses Symmetry and Voluntary movement I - Normal II - Mild weakness, no asymmetry III - Mod weakness, no asymmetry IV - Gross weakness, asymmetry as rest V - Minimal movement, asymmetry at rest VI - No movement Sunnybrook Facial Grading Scale (0-100) - Resting Symmetry - Eye - Cheek - Mouth - Voluntary Movement & - Synkinesis - Forehead wrinkle (Front) - Eye closure (OOI) - Open mouth smile (Zyg, Ris) - Snarl (LLA, LLS) - Lip pucker (OOS, OOI)

Question 5

Nerve Injury - Recovery

Answer 5

Sunderland 1 - Neuropraxia Conduction block without axonal damage 8 weeks complete recovery 2 - Axon only Complete recovery in 2-4 months 3 - Endoneurium - around individual axons Incomplete recovery if still present at 3 months 4 - Perineurium - around nerve fascicles Incomplete recovery if still present at 3 months Likely neuroma 5 - Neurotmesis - Epineurium Loss of continuity of the whole nerve Incomplete recovery - Likely neuroma or neuropathy

Question 6

Nerve Injury - Management

Answer 6

Follow up and Neurosensory testing - 2 weeks - 1 month - Neuropraxia - complete recovery - Some improvement - Sunderland 1 or 2 - No improvement - MRI to exclude neuroma - 3 month - No improvement - indicates Sunderland 3 or higher - Some improvement - consider MRI and continue monitoring Medical - NSAIDs, Steroids, PPI - Shanti 2013 - Vit B12 - Dysaesthesia - Rafael 2016 - Topical capsaicin - TCA, Pregabalin, SSRI, Anticonvulsants Surgical - Observed - Repair 8-0 tension free - Unobserved Indications - Bagheri 2012 - No/minimal improvement in hypoaesthesia by 3/12 - Abnomal Level B testing (>Sunderland 3) - Persistant dysaesthesia - Worsening symptoms or new dysaesthesia Contraindications - Medically compromised - 12 months post injury - Extreme age - Central pain

Question 7

Nerve Injury - Repair success rate

Answer 7

Bagheri 2012 - 80% - IAN - 90% - Lingual Nerve Pogrel 2002 - 50% success rate if done within 3-4 months - Higher success rate - Short time to repair - hypoaesthesia rather than dysaesthesia - Younger age - Lingual > IAN

Question 8

Nerve Injury - Neurosensory Testing

Answer 8

Nizam & Ziccardi 2015 - Lingual - Test taste - Differentiate between paresthesia vs dysaesthesia - Paraesthesia - Level A - dynamic light touch (A alpha) 2 point (opening calipers is dynamic): 4mm lip, 3mm tongue **normal = ** Sunderland 1, Abnormal = Sunderland 2 - Level B - static light touch 2mg normal (monofilaments) (A beta)** Sbnormal = sunderland 3** - Level C - pinprick/cold (A delta, C fibres) Abnormal = Sunderland 4 No response at all = Sunderland 5 - Dysaesthesia - Level A - allodynia: pain in response to non painful stimuli - Level B - hyperpathia (time): pain persists when stimulus removed - Level C - hyperalgesia: response to pain disproportional If dysesthesia, use diagnostic nerve block If relief, refer for microsurgery If no relief, central process and consider pharmacologic treatment

Question 9

Facial Nerve Injury - Grading Scale

Answer 9

• House-Brackmann Scale
  Initially conducted for acoustic neuromas
  
  • Examines two components
    
    • Resting
    • Movement
      
      • Measured on a 1cm scale compared to the contralateral side
      • Breaks down movement into Forehead, Eye and Mouth
  • Grading Scale
    
    • I - Normal
    • II - Mild dysfunction - Normal symmetry, Slight weakness, Slight synkinesis
    • III - Mod dysfunction - Normal symmetry, Obvious difference, noticeable synkinesis
    • IV - Mod/Severe dysfunction - Normal symmetry, Obvious weakness and disfiguring,
    • V - Severe dysfunction - Asymmetry, Barely perceptible motion
    • VI - Total paralysis
      ​
• Sunnybrook Facial Grading Scale
  
  • 0 - 100 Grading scale
  • Compares 3 components
    
    • Resting symmetry
      
      • Eye
      • Cheek
      • Mouth
    • Voluntary movement
      
      • Forehead wrinkle
      • Eye closure
      • Open mouth smile
      • Snarl
      • Lip pucker
    • Synkinesis