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

Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a type of orofacial neuralgia characterized by severe, paroxysmal pain that follows the anatomical distribution of the trigeminal nerve (cranial nerve V). It is often described as one of the most painful conditions known, and understanding its features, triggers, and patterns is essential for effective management.

Features of Trigeminal Neuralgia

  1. Anatomical Distribution:

    • Trigeminal neuralgia follows the distribution of the trigeminal nerve, which has three main branches:
      • V1 (Ophthalmic): Supplies sensation to the forehead, upper eyelid, and parts of the nose.
      • V2 (Maxillary): Supplies sensation to the cheeks, upper lip, and upper teeth.
      • V3 (Mandibular): Supplies sensation to the lower lip, chin, and lower teeth.
    • Pain can occur in one or more of these dermatomes, but it is typically unilateral.

  2. Trigger Zones:

    • Patients with trigeminal neuralgia often have specific trigger zones on the face. These are areas where light touch, brushing, or even wind can provoke an episode of pain.
    • Stimulation of these trigger zones can initiate a paroxysm of pain, leading to sudden and intense discomfort.

  3. Pain Characteristics:

    • The pain associated with trigeminal neuralgia is described as:
      • Paroxysmal: Occurs in sudden bursts or attacks.
      • Excruciating: The pain is often severe and debilitating.
      • Sharp, shooting, or lancinating: Patients may describe the pain as electric shock-like.
      • Unilateral: Pain typically affects one side of the face.
      • Intermittent: Attacks can vary in frequency and duration.

  4. Latency and Refractory Period:

    • Latency: This refers to the short time interval between the stimulation of the trigger area and the onset of pain. It can vary among patients.
    • Refractory Period: After an attack, there may be a refractory period during which further stimulation does not elicit pain. This period can vary in length and is an important aspect of the pain cycle.

  5. Pain Cycles:

    • Paroxysms of pain often occur in cycles, with each cycle lasting for weeks or months. Over time, these cycles may become more frequent, and the intensity of pain can increase with each attack.
    • Patients may experience a progressive worsening of symptoms, leading to more frequent and severe episodes.

  6. Psychosocial Impact:

    • The unpredictable nature of trigeminal neuralgia can significantly impact a patient's quality of life, leading to anxiety, depression, and social withdrawal due to fear of triggering an attack.

Management of Trigeminal Neuralgia

  1. Medications:

    • Anticonvulsants: Medications such as carbamazepine and oxcarbazepine are commonly used as first-line treatments to help control pain.
    • Other Medications: Gabapentin, pregabalin, and baclofen may also be effective in managing symptoms.

  2. Surgical Options:

    • For patients who do not respond to medication or experience intolerable side effects, surgical options may be considered. These can include:
      • Microvascular Decompression: A surgical procedure that relieves pressure on the trigeminal nerve.
      • Rhizotomy: A procedure that selectively destroys nerve fibers to reduce pain.

  3. Alternative Therapies:

    • Some patients may benefit from complementary therapies such as acupuncture, physical therapy, or biofeedback.

LASER THERAPY – VERY HIGH YIELD

Laser Physics & Mechanisms

Q – Switching

  • Creates exceptionally short pulse time
  • Limits lateral tissue damage
  • Used with short thermal relaxation time tissues
  • Example: Ruby laser for tattoo removal

CO₂ Laser Parameters

  • Continuous wave: Coagulation necrosis zone ~500 microns
  • Superpulse/Ultrapulse: Reduces zone to <100 microns

Tissue Interactions (4 Basic Types)

  1. Reflection
  2. Scatter
  3. Transmission
  4. Absorption

Tissue Reactions Post – Absorption (4 Types)

  1. Photothermal
  2. Photoablative
  3. Photochemical
  4. Photoacoustic

Clinical Applications

Cosmetic Skin Resurfacing

  • Primary lasers: CO₂ laser, Er:YAG laser

Laser Delivery Systems

  1. Fiberoptic guide
  2. Articulated arm laser
  3. Hollow wave guide technology (most recent)

  • Primary site of LA action: Amygdala (limbic system).
  • pKa of lignocaine: 7.8.
  • Pregnancy supine hypotension: Due to IVC compression.
  • Pregnant patient position: Left lateral decubitus.
  • Corticosteroids in pregnancy: FDA Category C.
  • Ketamine action site: Thalamocortical junction.
  • Atracurium & cisatracurium metabolism: Hoffman elimination.
  • Neuralgia treatment: Carbamazepine arrests Na⁺ channels in inactive state.

Anatomy

  • Course: Mandibular foramen → mental foramen
  • Branches: Dental branches, mental nerve, incisive nerve
  • Function: Sensation to mandibular teeth, chin, lower lip
  • Clinical significance: Most commonly injured nerve in oral surgery

Common Injury Scenarios

  • Third molar extraction: Most frequent cause
  • Implant placement: Especially posterior mandible
  • Orthognathic surgery: Bilateral sagittal split osteotomy
  • Mandible fractures: Direct trauma or surgical treatment
  • Local anesthesia: Rare but reported

Repair Considerations

  • Timing: Early repair (within 3-6 months) preferred
  • Surgical approach: Intraoral vs extraoral
  • Magnification: Operating microscope or loupes essential
  • Patient factors: Age, overall health, functional expectations

Surgical Technique for IAN Repair

Preoperative Planning

  • Imaging: CT or MRI to assess defect size
  • Function testing: Baseline sensory evaluation
  • Patient counseling: Realistic expectations

Surgical Steps

  1. Exposure: Careful dissection to identify nerve ends
  2. Debridement: Remove scar tissue and neuromas
  3. Assessment: Determine gap size and repair options
  4. Repair: Direct suture vs grafting based on gap
  5. Closure: Tension-free, layered closure

Postoperative Care

  • Protection: Avoid trauma to surgical site
  • Monitoring: Regular sensory function assessment
  • Rehabilitation: Sensory re-education if appropriate
  • Timeline: Monitor recovery for 18-24 months

Condylar Fractures

Condylar fractures are a significant type of mandibular fracture, accounting for a notable percentage of all mandibular injuries. Understanding their characteristics, associated injuries, and implications for treatment is essential for effective management. Below is a detailed overview of condylar fractures.

1. Prevalence and Associated Injuries

  • Incidence: Condylar fractures account for 26-57% of all mandibular fractures.
  • Associated Fractures: Approximately 48-66% of patients with a condylar fracture will also have a fracture of the body or angle of the mandible.
  • Unilateral Fractures: Unilateral fractures of the condyle occur 84% of the time.

2. Types of Condylar Fractures

  • Subcondylar Fractures: Approximately 62% of condylar fractures are classified as subcondylar.
  • Condylar Neck Fractures: About 24% are neck fractures.
  • Intracapsular Fractures: Approximately 14% are intracapsular.
  • Severe Displacement: About 16% of condylar fractures are associated with severe displacement.

3. Mechanism of Injury

  • Bilateral Fractures: Symmetrical impacts can cause bilateral fractures, with contralateral fractures occurring due to shearing forces, which are thought to produce intracapsular fractures.

4. Displacement Patterns

  • Dislocation: The condylar fragment can dislocate out of the fossa, typically in an anterior direction, but it can also displace in any direction.

5. Clinical Implications of Fractures

  • Unilateral Fractures: A unilateral fracture with sufficient fragment overlap or dislocation can lead to premature posterior contact on the affected side and midline deviation toward the affected side.
  • Bilateral Fractures: Bilateral condylar fractures with fragment overlap or dislocation can result in bilateral posterior premature contact, anterior open bite, and minimal or no chin deviation.

6. Comminuted Fractures

  • Challenges: Comminuted mandibular fractures with bilateral condylar fractures can produce crossbites and increase the interangular distance, complicating accurate reduction. Failure to recognize and correct this increased interangular distance can lead to malocclusion after fixation.

7. Radiologic Imaging

  • Imaging Requirements: Radiologic imaging in two planes is necessary to diagnose condylar fractures effectively. Commonly used imaging techniques include:
    • Orthopantomogram (OPG): Provides a panoramic view of the mandible and can help identify fractures.
    • Posteroanterior (PA) Mandible View: Offers additional detail and perspective on the fracture.

Classes of Hemorrhagic Shock (ATLS Classification)

Hemorrhagic shock is a critical condition resulting from significant blood loss, leading to inadequate tissue perfusion and oxygenation. The Advanced Trauma Life Support (ATLS) course classifies hemorrhagic shock into four classes based on various physiological parameters. Understanding these classes helps guide the management and treatment of patients experiencing hemorrhagic shock.

Class Descriptions

  1. Class I Hemorrhagic Shock:

    • Blood Loss: 0-15% (up to 750 mL)
    • CNS Status: Slightly anxious; the patient may be alert and oriented.
    • Pulse: Heart rate <100 beats/min.
    • Blood Pressure: Normal.
    • Pulse Pressure: Normal.
    • Respiratory Rate: 14-20 breaths/min.
    • Urine Output: >30 mL/hr, indicating adequate renal perfusion.
    • Fluid Resuscitation: Crystalloid fluids are typically sufficient.

  2. Class II Hemorrhagic Shock:

    • Blood Loss: 15-30% (750-1500 mL)
    • CNS Status: Mildly anxious; the patient may show signs of distress.
    • Pulse: Heart rate >100 beats/min.
    • Blood Pressure: Still normal, but compensatory mechanisms are activated.
    • Pulse Pressure: Decreased due to increased heart rate and peripheral vasoconstriction.
    • Respiratory Rate: 20-30 breaths/min.
    • Urine Output: 20-30 mL/hr, indicating reduced renal perfusion.
    • Fluid Resuscitation: Crystalloid fluids are still appropriate.

  3. Class III Hemorrhagic Shock:

    • Blood Loss: 30-40% (1500-2000 mL)
    • CNS Status: Anxious or confused; the patient may have altered mental status.
    • Pulse: Heart rate >120 beats/min.
    • Blood Pressure: Decreased; signs of hypotension may be present.
    • Pulse Pressure: Decreased.
    • Respiratory Rate: 30-40 breaths/min.
    • Urine Output: 5-15 mL/hr, indicating significant renal impairment.
    • Fluid Resuscitation: Crystalloid fluids plus blood products may be necessary.

  4. Class IV Hemorrhagic Shock:

    • Blood Loss: >40% (>2000 mL)
    • CNS Status: Confused or lethargic; the patient may be unresponsive.
    • Pulse: Heart rate >140 beats/min.
    • Blood Pressure: Decreased; severe hypotension is likely.
    • Pulse Pressure: Decreased.
    • Respiratory Rate: >35 breaths/min.
    • Urine Output: Negligible, indicating severe renal failure.
    • Fluid Resuscitation: Immediate crystalloid and blood products are critical.

Complication Cause/Mechanism Management Strategy
Paraesthesia Trauma to nearby nerves (e.g., inferior alveolar, mental nerve) Usually resolves spontaneously; monitor; prescribe vitamin B complex; if persistent, refer to specialist
Ecchymoses Soft tissue trauma or bleeding into subcutaneous tissue Cold compress immediately post-op; warm compress after 24 hrs; reassure patient
Stitch abscess Localized infection at suture site due to contamination Remove suture; drain pus; antiseptic rinse; antibiotics if needed
Swelling Inflammatory response to surgery Cold compress first 24 hrs; anti-inflammatory medication
Pain Tissue trauma, inflammation Analgesics; proper post-op instructions
Delayed healing Poor oral hygiene, systemic conditions Improve oral hygiene; manage systemic factors; follow-up care
MDS SUBJECTS

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