CLASSIFICATION OF NERVE INJURIES

Etiology of nerve injuries , anatomy of peripheral nerves, sedon's classification, neuropraxia, axonotemesis, Neurotemesis, Sunderland's classification, management of nerve injuries,

1. CLASSIFICATION OF NERVE INJURIES KEERAT KUCKREJA 150301176 IV YEAR

2. ETIOLOGY Trauma is the major cause of nerve injuries I atrogenic errors D elivery of LA Oral surgical procedures E ndodontic procedures Periodontal surgeries C hemical agents INFRAORBITAL NERVE Lefort II and Lefort III level osteotomies Caldwell luc procedure Orbital osteotomies Fractures of midface and orbit

3. LINGUAL NERVE Mandibular third molar removal Excision of submandibular and sublingual glands Iatrogenic instrumentation of floor of mouth Mandibular tumor removal Osteotomies INFERIOR ALVEOLAR NERVE Removal of any impacted mandibular tooth Endosteal implant placement Mandibular osteotomies Mandibular cyst and tumor removal Mandibular resection Orthognathic and preprosthetic surgeries

4. ANATOMY OF PERIPHERAL NERVE

5. SEDDON’S CLASSIFICATION (1942) SEDDON CLASSIFIED NERVE INJURIES INTO ACC TO THE AMOUNT OF NERVE TISSUE DAMAGED AND TISSUE STILL INTACT: NEUROPRAXIA AXONOTMESIS NEUROTMESIS

6. NEUROPRAXIA: Mild temporary injury due to compression or retraction of nerve There is a conduction block due to anoxia from the interruption of epineural or endoneural blood supply causing intrafasicular edema No axonal degeneration distal to the site of injury Temporary conduction block (sensory loss) Spontaneous recovery within 4 weeks No surgical intervention required

7. AXONOTMESIS: Disruption or loss of continuity of some axons , which undergo W allerian degeneration distal to the site of injury General structure of the nerve remains intact Prolonged conduction failure Intial signs of recovery do not appear until after 1-3 months Eventual recovery less than normal (paresis and hypoesthesia) Sensory nerve injuries may develop persistent painful sensation (dysesthesia)

8. NEUROTEMESIS: Complete severance of all the layers of the nerve Total permanent conduction blockade of all the impulses (paresthesia, anesthesia) The discontinuity between the proximal and the distal segment is filled up with scar tissue No recovery without surgical intervention

9. SUNDERLAND’S CLASSIFICATION (1978 )

10. STAGES OF NERVE HEALING

11. CLINICAL FEATURES Deep seated pain Diffuse and continuous in nature Functional loss if motor nerve is involved Drooling T ongue biting Thermal burns Changes in speech Swallowing T aste perception alterations The area supplied by the sensory branch may become hyperesthetic of hypoesthetic .

12. EVALUATION Ascertain patient’s main complaint : regarding loss of sensation Pain A bnormal sensation or functional impairment Patient’s history : Trauma or surgical procedure associated with injury Date of incident Progress of symptoms Progress of recovery : E xcellent prognosis : return of sensation within first 4 weeks ( neuropraxia ) Fair prognosis : return within 1-3 months ( axonotmesis ) Poor prognosis : lack of recovery for 12 weeks or longer ( neurotmesis )

13. CLINICAL NEUROSENSORY EXAMINATION : Static light touch Brush directional discrimination T wo point discrimination Pin pressure nociceptive discrimination Thermal discrimination STEP 1: MAP THE AREA OF SENSORY DISTURBANCE

14. STATIC LIGHT TOUCH :Performed using Von Frey filaments 2.BRUSH DIRECTIONAL DISCRIMINATION : Performed using camel hair brush

15. 3.TWO POINT DISCRIMINATOR 4.PIN PRESSURE NOCICEPTION

16. 5. THERMAL DISCRIMINATION 6.LOCAL ANESTHETIC NERVE BLOCKS : Failure to relieve pain in the presence of effective nerve block suggests a central sympathetic or psychological rather than a peripheral cause of dysesthesia

17. MANAGEMENT MEDICAL MANAGEMENT: Topical Anesthetics 5% viscous lidocaine gel NSAIDS Ketoprofen 10-20% PLO base Sympathomimetics Clonidine 0.01% PLO base or patch Anticonvulsants Carbamazepne 2% PLO base TCA Amitriptyline 2% PLO base Topical medications Systemic Pharmacological Agents Local anesthetics Corticosteroids NSAIDS Antidepressants Muscle relaxants Benzodiazepines

18. SURGICAL MANAGEMENT: Indications for Microneurosurgery Contraindications for Microneurosurgery : Observed nerve severance Central neuropathic pain Total anesthesia beyond 3 months Dysesthesia not abolished by the LA nerve block Dysesthesia beyond 4 months Improving sensation Sever hypoesthesia without improvement beyond 4 months Medically compromised patient Excessive delay after injury PRINCIPLES OF MICRONEUROSURGERY Controlled General anesthesia Visualization Magnification of surgical field Good hemostasis Removal of pathological tissue or foreign material Proper alignment Coaptation of proximal and distal nerve stumps Suturing without tension

19. SURGICAL APPROACH

20. IN CASE OF WIDER GAPS NERVE REGENRATION An A utogenous nerve graft is interposed between nerve stumps to eliminate tension The G reat auricular and the S ural nerves are common donors Short span (1-3cm) nerve gaps can be repaired with guided nerve regeneration Axonal growth directed by a tube made up of alloplastic materials or autogenous tissues The peripheral nerve guidance conduit is surgically implanted, the proximal and the distal nerve stumps are sutured into the conduit, T his creates a physical guiding pathway for nerve growth as well as a reservoir of growth factors that further guide the sprouting daughter axons in the proximal nerve stump

21. POST OPERATIVER MANAGEMENT Standard protocols are followed regarding antibiotics, analgesics, fluids and discharge The neck sutures are removed at 5-7 days after surgery and leg sutures after 10 days POST OPERATIVE COURSE Variable period of complete anetgesia ,sometimes upto 3 months Regrowth occurs at 3mm/day ,that means 3 cm in 1 month Dysesthesia is always possible after nerve surgery Best prognosis for an anesthetic nerve operated on within 3 months

22. BIBLIOGRAPHY 1.Tubbs RS , Rizk E, Shoja MM, Loukas M, Barbaro N, Spinner RJ, Nerves and Nerve injuries 2. Trigeminal nerve Injury and Management , Kristopher Lee (OMFS , mount Sinai hospital 3. Nilima Malik text book for oral surgery 4. Google images

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