Nerve injury basic Maxillofacial nerve injury

2. NERVE INJURY
PRESENTED TO :PROF DR NOOR UL
WAHAB
PRESENTED BY : DR MUSHTAQ
AHMAD RESIDENT ORAL AND
MAXILLOFACIAL SURGERY

3. CONTENTS
• ANATOMY OF NERVE
• ETIOLOGY OF NERVE INJURY
• CLASSIFICATION OF NERVE INJURY
• NERVE HEALING
• CLINICALEVALUATION
• MANAGEMENT
• LITERATURE REVIEW
• REFERENCES

4. • HIGHEST DENSITY OF PERIPHERAL NERVE RECEPTORS.
• NEUROLOGIC DISTURBANCES LESS TOLERABLE IN THE
HEAD AND NECK THAN IN OTHER BODY PARTS
• INJURY TO THE PERIPHERAL BRANCHES
CAN BE DEVASTATING BECAUSE OF THE EFFECTS ON
• SPEECH, DEGLUTITION, SWALLOWING, MASTICATION,
AND TASTE
• THE IMPACT ON SOCIAL INTERACTIONS.

5. ANATOMY (MICROANATOMY)
• SAME FOR ALL PERIPHERAL NERVES NERVES CONTAINING MYELINATED
• AND UNMYELINATED FIBERS IN A RATIO OF 1 : 4.
• THE DIFFERENCE BETWEEN THE TWO TYPES OF FIBERS IS THE NUMBER OF
SCHWANN CELLS THAT SURROUND EACH FIBER WITH NODES OF RANVIER
THAT
• PERMIT RAPID SALTATORY NERVE CONDUCTION

6. CONTIN…
• IN THE MYELINATED FIBER, THE RATIO OF NERVE AXONS AND SCHWANN CELLS IS 1
: 1, WHEREAS IN THE UNMYELINATED FIBER THE SCHWANN CELL ENVELOPS
SEVERAL AXONS.
• BAND OF BÜNGNER (LAMINAR MYELIN SHEATH):THE MEMBRANE, OR BASAL
LAMINA, CREATED BY THE SCHWANN CELL AS IT WRAPS AROUND THE AXON AND
RUNS THE ENTIRE LENGTH OF THE AXON CRUCIAL FOR THE PROCESS OF NERVE
REGENERATION
• ALTHOUGH MYELIN MAY BE DESTROYED DURING NERVE INJURY, SCHWANN
• CELLS SURVIVE AND PLAY A MAJOR SUPPORTIVE ROLE IN NERVE RECOVERY AND
REPAIR

7. • THE LENGTH OF THE AXON SURROUNDED BY A SINGLE SCHWANN CELL IS
KNOWN AS THE INTERNODE
• AND THE SMALL AREA (0.3 TO 2.0 MM) BETWEEN THE INTERNODES, WHERE
THE AXON IS NOT MYELINATED, IS KNOWN AS A NODE OF RANVIER
• . IN EACH NODE OF RANVIER, CERTAIN IONS DIFFUSE, WHICH CAUSES NERVE
DEPOLARIZATION AND REPOLARIZATION AND ALLOWS FOR THE CONDUCTION
OF NERVE IMPULSES ALONG THE NERVE FIBER

8. COLLAGEN
• PROVIDES THE FRAMEWORK THAT SURROUNDS THE NERVE AND CREATES THE
STRUCTURAL ARCHITECTURE WITHIN THE NERVE.
• ENDONEURIUM :IS THE FIRST ORGANIZATION OF FINE COLLAGEN FIBERS AROUND
EACH NERVE FIBER AXON.
• FASCICLES. SEVERAL BUNDLES OF ENDONEURIAL GROUPS , KNOWN AS
FASCICLES.
• ARE GROUPED TOGETHER AND SURROUNDED BY A SECOND LAYER OF COLLAGEN
FIBERS (AND MESOTHELIAL CELLS) CALLED THE PERINEURIUM
• EPINEURIUM: OUTER LAYER OF CONNECTIVE TISSUE SUPPORTING THE NERVE,
ALONG WITH SOME ELASTIC FIBERS. PROVIDES SOME PROTECTION AGAINST
COMPRESSION.
• MESONEURIUM: IS RESPONSIBLE FOR ALLOWING SOME FREEDOM OF MOVEMENT
• OF THE NERVE IS KNOWN AS THE MESONEURIUM, OR ADVENTITIA OF THE NERVE.

10. MECHANISM OF NERVE INJURY
• DIRECT OR INDIRECT TRAUMA ,COMPRESSION ,STRETCH ,LACERATION
• COMPARTMENT SYNDROME ,CHEMICAL INJURY.
• TRAUMATIC INJURIES: JAW FRACTURES.
• IATROGENIC INJURIES:
• LOCAL ANESTHESIA (LA)
• ORAL SURGICAL PROCEDURES—EXTRACTIONS, IMPLANTS, BONE
• GRAFTING, ORTHOGNATHIC SURGERY, ABLATIVE SURGERY.
• PERIODONTAL SURGERY
• ENDODONTICS—CHEMICAL MATERIAL, HEMOSTATIC AGENTS.

11. ETIOLOGY
• INFERIOR ALVEOLAR NERVE (IAN): MANDIBULAR
IMPACTED THIRD MOLARS OR ANY IMPACTED MANDIBULAR TOOTH REMOVAL.
• MANDIBULAR MOLAR ENDODONTICS,
• ENDOSTEAL IMPLANT PLACEMENT, VISOR OSTEOTOMIES,
• ALVEOLECTOMY , MANDIBULAR BODY/RAMUS/ SUB APICAL OSTEOTOMIES,
MANDIBULAR CYST OR TUMOR REMOVAL, MANDIBULAR RESECTION,
• FRACTURES OF MANDIBULAR BODY AND ANGLE REGION,
• PRE PROSTHETIC SURGERY, GENIO PLASTY ,
• GUNSHOT WOUNDS, OSTEOMYELITIS
ORTHO GNATHIC SURGERY, PARTICULARLY SAGITTAL MANDIBULAR
OSTEOTOMY,

12. ETIOLOGY
• LINGUAL NERVE (LN):
• MANDIBULAR THIRD MOLAR REMOVAL.
• EXCISION OF THE SUBLINGUAL OR SUBMANDIBULAR GLAND.
• IATROGENIC INSTRUMENTATION OF FLOOR OF THE MOUTH.
• SULCOPLASTIES OF LINGUAL VESTIBULE.
• MANDIBULAR TUMOR REMOVAL.
• MANDIBULAR RAMUS OSTEOTOMIES.

13. ETIOLOGY
• INFRA ORBITAL NERVE:
• LEFORT II, III LEVEL OSTEOTOMIES,
• CALDWELL-LUC PROCEDURE, ORBITAL OSTEOTOMIES,
• MAXILLO MANDIBULAR CONTUSIONS AND FRACTURES OF THE MID FACE AND
ORBITS.
• FOLLOWING MID FACE TRAUMA, INFRA ORBITAL NERVES ARE ALMOST ALWAYS
INVOLVED, AND CHRONIC IMPAIRMENT PERSISTS IN UP TO 35–50% OF PATIENTS.

16. CLASSIFICATION OF NERVE INJURY
• SEDDON’S CLASSIFICATION :
• BASED ON THE TIME BETWEEN INJURY AND RECOVERY AND
DEGREE OF RECOVERY.
• INCLUDES THREE LEVELS OF NERVE INJURY

17. NEUROPRAXIA
• MILD NERVE MANIPULATION, TRACTION, OR COMPRESSION INJURY; IT IS
• CHARACTERIZED BY A REVERSIBLE CONDUCTION BLOCK WITH A FAVORABLE
OUTCOME, WITH RAPID AND COMPLETE RECOVERY WITHIN DAYS TO A FEW
WEEKS OF THE EVENT.
• NO AXONAL DEGENERATION OCCURS IN NEUROPRAXIC INJURIES
• AND DAMAGE IS CONFINED TO THE ENDONEURIUM ONLY.
• THE INTEGRITY OF THE AXON IS MAINTAINED.
• SPONTANEOUS RECOVERY USUALLY OCCURS WITHIN 24 HOURS TO 2 MONTHS
OR LESS TIME. NO SURGICAL INTERVENTION IS REQUIRED

19. AXONOTMESIS
• INVOLVES AXONAL DAMAGE,
• VARIABLE DEGREES OF DEMYELINATION AND AXONAL INJURY AND
THEREFORE SPONTANEOUS RECOVERY VARY SIGNIFICANTLY IN THIS
CATEGORY OF INJURIES.
• PROLONGED CONDUCTION FAILURE.
• COMPLETE RECOVERY MAY BE WITHIN 12 MONTHS,
• ONSET OF INITIAL SIGNS OF
• RECOVERY OF NERVE FUNCTION—SENSORY RETURN ONLY AFTER
2–4 MONTHS AFTER INJURY.

21. NEUROTMESIS
• IMPLIES COMPLETE OR NEAR-COMPLETE NERVE TRANSECTION THAT
INCLUDES EPINEURIAL DISCONTINUITY.
• THERE IS A TOTAL PERMANENT CONDUCTION BLOCK OF ALL IMPULSES
(PARALYSIS, ANESTHESIA).
• SPONTANEOUS RECOVERY IS UNLIKELY, WHEREAS NEUROMA FORMATION MAY
OCCUR MORE COMMONLY.
• NO RECOVERY IS EXPECTED WITHOUT SURGICAL INTERVENTION.

23. SUNDERLAND CLASSIFICATION SYSTEM
• BASED ON HISTOLOGIC FINDINGS OF THE DEGREE OF NERVE INVOLVEMENT
• DESCRIBED A FIVE-DEGREE CLASSIFICATION SYSTEM ( I TO V DEGREES OF
NERVE INJURY)

25. NERVE HEALING
• THE BASIC PROCESS OF NERVE HEALING REMAINS THE SAME
AND INVOLVES A SEQUENCE OF DEGENERATION FOLLOWED BY
REGENERATION
• DEGENERATION: 2 TYPES OF DEGENERATION OCCUR
• (1) SEGMENTAL DEMYELINATION :MYELIN SHEATH IS DISSOLVE IN
ISOLATED SEGMENTS
• CAUSES A SLOWING OF CONDUCTION VELOCITY AND MAY
PREVENT NERVE IMPULSES
• SYMPTOMS INCLUDE PARESTHESIA
,DYSESTHESIA,HYPERESTHESIA AND HYPOESTHESIA.
• CAN OCCUR AFTER NEUROPRAXIC INJURIES

26. (2) WALLERIAN DEGENERATION:
• AXON AND MYELIN SHEATH DITAL TO TO SITE OF NERVE TRUNK
UNDERGO DISSENTEGRATION IN THEIR ENTITY
• STOP ALL NERVE CONDUCTION DISTALO TO PROXIMAL AXONAL
STUMP .
• OCCUR IN NERVE TRANSSECTION AND OTHER DESTRUCTIVE
POCESSES
• LIKELY TO UNDERGO SPONTANEOUS REGENERATION.

27. REGENERATION
• CAN BEGIN ALMOST IMMEDIATELY AFTER NERVE INJURY
• PROXIMAL NERVE STUMP SEND OUT A GROUP OF NEW FIBERS (AXONAL SPROUTS OR THE
GROWTH CONE) THAT GROW DOWN THE REMNANT SCHWANN CELL TUBE.
• GROWTH PROGRESS AT A RATE OF 1 TO 1.5 MM/DAY AND CONTINUES UNTILL THE SITE
INNERVATED BY NERVE IS REACHED OR NERVE NERVE REGENERATION BLOCKED BY
INTERPOSED FIBROUS CONNECTIVE TISSUE AND NERVE TISSUE OR BONE
• NEW MYELIN SHEATH MAY FORM AS THE AXON INCREASE IN DIAMETER
• AS THE FUNCTION RESTORED PATIENT MAY EXPERIENCED ALETRED SENSATION IN THE
PREVIOUSLY ANESTHETIC AREA.

28. • NEUROMA FORMATION.
• NEUROMAS REPRESENT A DISORGANIZED MASS OF COLLAGEN
FIBERS AND NERVE SPROUTS THAT ARE RANDOMLY ORIENTED
• NEUROMAS CAN BE OF THE FOLLOWING TYPES:
• AMPUTATION (STUMP NEUROMA)
• NEUROMA-INCONTINUITY
• CENTRAL OR FUSIFORM NEUROMA
• LATERAL (LATERAL EXOPHYTIC, OR LATERAL ADHESIVE
NEUROMA.

30. EVALUATION
• A DETAILED HISTORY AND CLINICAL EXAMINATION, ALONG WITH OBJECTIVE
TESTING THAT INCLUDES
• THE USE OF SPECIFIC NEUROSENSORYTESTS (NSTS),
• PAIN QUESTIONNAIRES, AND
• VISUAL ANALOGUE SCALES,
• CRUCIAL IN THE ASSESSMENT OF THE PATIENT WHO HAS SUSTAINED TRAUMA
TO THE TRIGEMINAL NERVE.

31. NEURO SENSORY TESTING
• THE CLINICAL NST PROTOCOL INVOLVES MECHANORECEPTIVE FIBER TESTING
PERFORMED FIRST (TWO-POINT DISCRIMINATION, STATIC LIGHT TOUCH,
DIRECTIONAL DISCRIMINATION, AND VIBRATORY SENSE),
• FOLLOWED BY NOCICEPTIVE FIBER TESTING (PAIN STIMULI AND THERMAL
DISCRIMINATION).

34. MANAGEMENT
• EARLY PROMPT MEDICAL AND SELECTIVE SURGERIES OF ACUTE
NERVE INJURIES MAY PREVENT PROGRESSION TO CHRONIC
REFRACTORY NEUROPATHIES AND DYSESTHESIAS;
• THEREFORE, IT IS RECOMMENDED THAT PATIENTS WITH
DYSFUNCTIONAL SENSORY DEFICITS AND INTRACTABLE PAIN
SHOULD BE TREATED AS SOON AS POSSIBLE

35. MEDICAL MANAGEMENT
• MEDICAL MANAGEMENT IS MOSTLY LIMITED FOR DYSESTHESIA/ NEUROPATHIC
PAIN
• ANTIBIOTICS, ANTI-INFLAMMATORY AGENTS, OPIATE ANALGESICS.
• PSYCHOSEDATIVE AGENTS.
• USE OF LOCAL ANESTHETIC NERVEBLOCKS WITH LONG-ACTING AGENTS.
• CORTICOSTEROIDS.
• RAPID-ACTING ANTICONVULSANT AGENTS, SUCH AS CLONAZEPAM.

36. SURGICAL MANAGEMENT
• CAREFUL PATIENT ASSESSMENT AND COLLECTION OF INFORMATION FROM
NEUROSENSORY TESTING ARE CRUCIAL IN THE DECISION MAKING PROCESS
FOR TREATMENT RECOMMENDATIONS, AND SPECIFICALLY THE NEED FOR
SURGICAL INTERVENTION

37. CONTIN….
• INDICATIONS
• COMPLETE ANESTHESIA
• <50% RESIDUAL SENSATION
(SUNDERALND III, IV, V)
• NO IMPROVEMENT WITHIN 3 MO AFTER
INJURY
• OBSERVED NERVE TRANSECTION
• EARLY DYSESTHESIA (NEUROMA
FORMATION)
• INTOLERABLE SUBJECTIVE
PARESTHESIA
• CONTRAINDICATIONS
• CONTINUING IMPROVEMENT IN
SENSATION
• LATE DYSESTHESIA (ESPECIALLY IAN)
• CENTRAL NEUROPATHIC PAIN
• COMPLEX REGIONAL PAIN SYNDROME
• TRIGEMINAL NEURALGIA
• ATYPICAL FACIAL PAIN
• ANESTHESIA DOLOROSA

38. MICRONEURO SURGERY
• BEST PERFORMED IN THE OPERATING ROOM UNDER LOOP MAGNIFICATION
• SURGICAL EXPOSURE TO ASSESS THE IAN, LN, MN, AND ION CAN BE EASILY
PERFORMED VIA INTRAORAL APPROACHES
• LINGUAL NERVE APPROACH: APPROACHED INTRA ORALLY VIA A PARA LINGUAL
OR LINGUAL GINGIVAL SULCUS INCISION
• THE PARA LINGUAL INCISION ALLOWS FOR A SMALL INCISION AND DIRECT
VISUALIZATION OF THE NERVE, BUT MAY BE MORE CHALLENGING TO IDENTIFY
THE NERVE STUMPS AFTER TRANSECTION BECAUSE OF RETRACTION INTO
THE SOFT TISSUES

39. • LINGUAL GINGIVAL SULCUS INCISION :A LONGER INCISION WITH ANTERIOR AND
POSTERIOR RELEASES, BUT THERE IS LESS RISK OF RETRACTION OF THE
NERVE ENDINGS DURING DISSECTION

40. • FOR THE IAN (AND MN), A VESTIBULAR INCISION WITH IDENTIFICATION OF THE
MN AND LATERAL DECORTICATION TO EXPOSE A PORTION OF THE IAN ARE
USUALLY ADEQUATE

42. • EXTERNAL NEUROLYSIS:DISSECTION OF THE NERVE FROM THE
SURROUNDING TISSUE BED FOR INSPECTION AND FURTHER MANIPULATION
• FOR THE LN, THIS MAY INVOLVE MICRODISSECTION OF THE NEUROVASCULAR
• BUNDLE FROM SURROUNDING SCAR TISSUE, WHEREAS FOR THE IAN IT MAY
IMPLY THE NEED FOR DECORTICATION OF THE IAC AND LATERALIZATION OF
THE IAN.
• IF FOREIGN MATERIAL OR BONE OR TOOTH FRAGMENTS ARE IDENTIFIED,
• THEY SHOULD BE REMOVED AT THIS STAGE.

43. NEUROMA
• IN CASES OF NEUROMA FORMATION, EXCISION FOLLOWED BY RESTORATION
OF NERVE CONTINUITY IS REQUIRED.
• CAREFUL EXAMINATION UNDER MAGNIFICATION OF THE NERVE STUMPS TO BE
• ANASTOMOSED IS CRUCIAL SO THAT HEALTHY NERVE TISSUES ARE REPAIRED;
• SCARRED AND NECROTIC NERVE STUMPS ARE COMPLETELY
• REMOVED AT 1.0-MM RESECTION INCREMENTS UNTIL NORMAL TISSUE IS
ENCOUNTERED
• FOR A DIRECT NEURORRHAPHY, EPINEURIAL SUTURING WITH THREE OR
FOUR 7.0 OR 8.0 NONREACTIVE SUTURES (NYLON) IS ADEQUATE FOR THE
TRIGEMINAL NERVE.

46. INDIRECT REPAIR
• CASES OF NERVE INJURY THAT RESULT IN NERVE CONTINUITY DEFECTS, OR
PREVENT PRIMARY TENSION-FREE REPAIR
• INTERPOSITIONAL GRAFTS MAY BE REQUIRED
• USUAL DONOR SITES FOR TRIGEMINAL NERVE REPAIR INCLUDE THE
• GREATER AURICULAR AND SURAL NERVES BECAUSE OF EASE OF
• ACCESS AND RELATIVELY LOW DONOR SITE MORBIDITY, AND ANESTHETIC
AREAS RELATIVELY TOLERABLE.*

48. • ALTERNATIVELY, SEVERAL OTHER MATERIALS MAY BE USED FOR INDIRECT
NEURORRHAPHY VIA ENTUBULATION TECHNIQUES,
• ALLOPLASTIC TUBES (SILASTIC, EXPANDED POLYTETRAFLUOROETHYLENE,
POLYESTER, POLYGLYCOLIC ACID POLYMER),
• VEIN GRAFTS, AND ALLOGENEIC NERVE GRAFTS .

51. REFRENCES
• CONTEMPORARY ORAL AND MAXILLOFACIAL SURGERY 7TH EDITION
• FONSECA ORAL AND MAXILLOFACIAL TRAUMA 4TH EDITION
• INFERIOR ALVEOLAR AND LINGUAL NERVE INJURIES: AN OVERVIEW
OFDIAGNOSIS AND MANAGEMENT FIRAT SELVI1, NELLI YILDIRIMYAN2, JOHN R.
ZUNIGA
• FRONT ORAL MAXILLOFAC MED 2021;3:28 |
HTTPS://DX.DOI.ORG/10.21037/FOMM-21-2