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Oral and Maxillofacial Surgery - NEETMDS- courses
Oral and Maxillofacial Surgery

Sedan Classification (3 Grades)

Classic classification based on functional and anatomical severity:

Grade I: Neurapraxia

  • Definition: Temporary loss of nerve function without structural damage
  • Pathophysiology: Local demyelination, nerve conduction block
  • Recovery: Complete, spontaneous recovery in weeks to months
  • Prognosis: Excellent (100% recovery expected)
  • Example: Temporary numbness after local anesthesia

Grade II: Axonotmesis

  • Definition: Axonal damage with intact nerve sheath (endoneurium preserved)
  • Pathophysiology: Axonal disruption, Wallerian degeneration distal to injury
  • Recovery: Spontaneous regeneration possible, slower process
  • Rate: ~1mm/day axonal regrowth
  • Prognosis: Good to fair, may have incomplete recovery
  • Timeline: Months to 1-2 years

Grade III: Neurotmesis

  • Definition: Complete nerve transection with disruption of all structures
  • Pathophysiology: Complete anatomical and functional discontinuity
  • Recovery: No spontaneous recovery without surgical intervention
  • Prognosis: Poor without repair, depends on surgical reconstruction
  • Treatment: Requires surgical repair or grafting

  • Soft palate lesion <2 cm: Excisional biopsy
  • Osteoradionecrosis (ORN): Post – radiation > 5000 – 6000 rads
  • Phlebectasia: Blue – black mucosal lesions (lips, tongue, palate)
  • Pain types:
    • Allodynia: Pain from non – painful stimulus
    • Dysesthesia: Painful abnormal sensation
    • Anesthesia: Total loss of sensation

Microvascular Trigeminal Decompression (The Jannetta Procedure)

Microvascular decompression (MVD), commonly known as the Jannetta procedure, is a surgical intervention designed to relieve the symptoms of classic trigeminal neuralgia by addressing the underlying vascular compression of the trigeminal nerve. This procedure is particularly effective for patients who have not responded to medical management or who experience significant side effects from medications.

Overview of the Procedure

  1. Indication:

    • MVD is indicated for patients with classic trigeminal neuralgia, characterized by recurrent episodes of severe facial pain, often triggered by light touch or specific activities.
  2. Anesthesia:

    • The procedure is performed under general anesthesia to ensure the patient is completely unconscious and pain-free during the surgery.
  3. Surgical Approach:

    • The surgery is conducted using an intraoperative microscope for enhanced visualization of the delicate structures involved.
    • The arachnoid membrane surrounding the trigeminal nerve is carefully opened to access the nerve.
  4. Exploration:

    • The trigeminal nerve is explored from its entry point at the brainstem to the entrance of Meckel’s cave, where the trigeminal ganglion (Gasserian ganglion) is located.
  5. Microdissection:

    • Under microscopic and endoscopic visualization, the surgeon performs microdissection to identify and mobilize any arteries or veins that are compressing the trigeminal nerve.
    • The most common offending vessel is a branch of the superior cerebellar artery, but venous compression or a combination of arterial and venous compression may also be present.
  6. Decompression:

    • Once the offending vessels are identified, they are decompressed. This may involve:
      • Cauterization and division of veins that are compressing the nerve.
      • Placement of Teflon sponges between the dissected blood vessels and the trigeminal nerve to prevent further vascular compression.

Outcomes and Efficacy

  • Immediate Pain Relief:

    • Most patients experience immediate relief from facial pain following the decompression of the offending vessels.
    • Reports indicate rates of immediate pain relief as high as 90% to 98% after the procedure.
  • Long-Term Relief:

    • Many patients enjoy long-term relief from trigeminal neuralgia symptoms, although some may experience recurrence of pain over time.
  • Complications:

    • As with any surgical procedure, there are potential risks and complications, including infection, cerebrospinal fluid leaks, and neurological deficits. However, MVD is generally considered safe and effective.

  • Normal clotting time: 8 – 15 minutes.
  • Platelet – rich plasma (1 unit): Raises platelet count by 7,000 – 10,000/μL.
  • Fresh frozen plasma (150 mL): Contains 200 μ factors VIII & IX, 400 mg fibrinogen.
  • Cryoprecipitate: Contains factors VIII, XIII, vWF, fibrinogen.
  • DIC marker: Elevated D – dimers.
  • Hemophilia factor levels: Majority have < 5%.
  • Surgery in hemophilia: Raise factor levels to 50 – 75%.

Landmark Description
Bregma Coronal + sagittal sutures junction
Vertex Highest point of cranium
Obelion Sagittal suture between parietal foramina
Lambda Lambdoid + sagittal sutures junction
Asterion Lambdoid, parietomastoid, occipitomastoid junction
Inion External occipital protuberance

  • Sentinel node: First node receiving lymphatic drainage from tumor.
  • Drooling management:
    • Bilateral submandibular duct relocation to posterior tonsillar pillar (preferred).
    • Bilateral parotid duct relocation.
  • Sublingual salivary gland tumors: <1% of salivary neoplasms; >80% malignant (adenoid cystic/mucoepidermoid carcinoma).
  • FNAC for salivary gland pathology: Specificity: 88 – 99%; Sensitivity: 71 – 93%.
  • Sistrunk operation: Thyroglossal duct cyst excision → includes hyoid bone & retrohyoid tract.

Sagittal Split Osteotomy (SSO)

Sagittal split osteotomy (SSO) is a surgical procedure used to correct various mandibular deformities, including mandibular prognathism (protrusion of the mandible) and retrognathism (retraction of the mandible). It is considered one of the most versatile osteotomies for addressing discrepancies in the position of the mandible relative to the maxilla.

Overview of the Procedure

  1. Indications:

    • Mandibular Prognathism: In cases where the mandible is positioned too far forward, SSO can be used to setback the mandible, improving occlusion and facial aesthetics.
    • Mandibular Retrognathism: For patients with a retruded mandible, the procedure allows for advancement of the mandible to achieve a more balanced facial profile and functional occlusion.
  2. Surgical Technique:

    • The procedure involves making a sagittal split in the ramus and posterior body of the mandible. This is typically performed through an intraoral approach, which minimizes external scarring.
    • The osteotomy creates two segments of the mandible: the proximal segment (attached to the maxilla) and the distal segment (which can be repositioned).
    • Depending on the desired outcome, the distal segment can be either advanced or set back to achieve the desired occlusal relationship and aesthetic result.
  3. Cosmetic Considerations:

    • The intraoral approach used in SSO helps to avoid visible scarring on the face, making it a highly cosmetic procedure.
    • The broader bony contact between the osteotomized segments promotes better healing and stability, which is crucial for achieving long-term results.
  4. Healing and Recovery:

    • The procedure typically results in good healing due to the increased surface area of contact between the bone segments.
    • Postoperative care includes monitoring for complications, managing pain, and ensuring proper oral hygiene to prevent infection.

Advantages of Sagittal Split Osteotomy

  • Versatility: SSO can be used to correct a wide range of mandibular discrepancies, making it suitable for various clinical scenarios.
  • Cosmetic Outcome: The intraoral approach minimizes external scarring, enhancing the aesthetic outcome for patients.
  • Stability: The broad bony contact between the segments ensures good stability and promotes effective healing.
  • Functional Improvement: By correcting occlusal discrepancies, SSO can improve chewing function and overall oral health.

Considerations and Potential Complications

  • Nerve Injury: There is a risk of injury to the inferior alveolar nerve, which can lead to temporary or permanent numbness in the lower lip and chin.
  • Malocclusion: If not properly planned, there is a risk of postoperative malocclusion, which may require further intervention.
  • Infection: As with any surgical procedure, there is a risk of infection at the surgical site.

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