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ROLE OF LASER SURGERIES IN ENT

(50 Marks | RGUHS Pattern)

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1. INTRODUCTION

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2. BASIC PRINCIPLES OF LASER PHYSICS

2.1 Einstein's Theory (1917) — Stimulated Emission

2.2 Components of a Laser System

┌─────────────────────────────────────────────────────────────┐
│                    LASER SYSTEM                             │
│                                                             │
│  ENERGY SOURCE → ACTIVE MEDIUM → OPTICAL RESONATOR         │
│  (Pump source)   (Lasing medium)  (Mirrors at each end)     │
│                       ↓                                     │
│               STIMULATED EMISSION                           │
│                       ↓                                     │
│              AMPLIFIED COHERENT LIGHT                       │
│                       ↓                                     │
│           OUTPUT COUPLER (partial mirror)                   │
│                       ↓                                     │
│                 LASER BEAM OUTPUT                           │
└─────────────────────────────────────────────────────────────┘

2.3 Properties of Laser Light

2.4 Laser-Tissue Interactions

LASER BEAM HITS TISSUE
        │
        ├──→ REFLECTION (off surface, ~4%)
        ├──→ SCATTERING (in tissue, sideways spread)
        ├──→ TRANSMISSION (passes through)
        └──→ ABSORPTION ←── CLINICALLY USEFUL
                 │
         ┌───────┴────────┐
         ↓                ↓
   PHOTOTHERMAL      PHOTOCHEMICAL
  (Heat → cut/      (Photodynamic
   coagulate/        therapy - PDT)
   vaporize)
         │
   ┌─────┴──────────────────┐
   ↓         ↓              ↓
<100°C    100°C          >300°C
Protein  Vaporization   Carbonization
denaturation (Steam)      (Char)
Hemostasis Tissue cut

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3. CLASSIFICATION OF LASERS USED IN ENT

3.1 By Active Medium

3.2 By Mode of Delivery

• Continuous wave (CW): Constant beam output → tissue vaporization
• Pulsed: Short pulses → less thermal spread → precise cutting
• Superpulsed/Ultrapulsed: Very rapid high-energy pulses → minimal thermal damage (CO₂ ultrapulse)

3.3 By Power

• Low-level laser therapy (LLLT): <500 mW → biostimulation, wound healing
• High-power surgical laser: >1 W → cutting, ablation, coagulation

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4. LASER SAFETY

Safety Classification (IEC 60825-1)

Safety Measures in ENT Laser Surgery

1. Eye protection — Wavelength-specific goggles for patient, surgeon, staff; corneal shields for patient (wet gauze)
2. Airway safety — Use laser-resistant endotracheal tubes (Lasertubus, Xomed Laser Shield II); fill cuff with saline + methylene blue (not air/N₂O — combustible); FiO₂ <0.4 during laryngeal work
3. Skin/tissue protection — Wet gauze/cottonoid patties around operative field
4. Fire prevention — No alcohol-based prep; avoid N₂O
5. Smoke evacuation — Laser plume contains viral particles (HPV DNA), toxic products → mandatory smoke evacuator
6. Warning signs — Post laser-in-use signs on all doors
7. Laser safety officer — Designated in all institutions

LASER FIRE TRIAD (analogous to "fire triangle")
         FUEL
          /\
         /  \
        /    \
   IGNITION──OXIDANT
    (Laser)  (O₂/N₂O)
    
Prevent by: Laser-safe tube + FiO₂ <0.4 + Wet drapes

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5. LASER SURGERY IN THE LARYNX

5.1 Equipment — Microlaryngoscopy Setup

OPERATING MICROSCOPE (400mm objective lens)
         │
   MICROMANIPULATOR
         │
    CO₂ LASER BEAM (invisible: guide beam = He-Ne red beam)
         │
LARYNGOSCOPE (suspended) → Patient under GA
         │
    Vocal cords in view

• Patient under GA, muscle relaxation
• Suspension laryngoscopy (Kleinsasser, Benjamin-Lindholm scope)
• Operating microscope (Carl Zeiss) at 400 mm focal length
• CO₂ laser via micromanipulator or KTP/Diode via flexible fiber

5.2 CO₂ Laser — Why Ideal for Larynx?

• High water absorption → precise cutting in soft tissue
• Minimal penetration depth (~0.1 mm) → less adjacent tissue damage
• Excellent hemostasis for vessels <0.5 mm
• Can be used in both contact and non-contact mode
• Cannot be delivered via flexible fiber (requires articulated arm) → used through rigid laryngoscope

5.3 Vocal Cord Lesions — Laser Treatment

A. Benign Vocal Cord Lesions

B. Recurrent Respiratory Papillomatosis (RRP)

• Caused by HPV 6 and 11; juvenile-onset and adult-onset types
• Laser is the gold standard treatment
• Goal: Preserve voice, maintain airway, NOT cure (incurable without adjuvant)
• CO₂ laser: Traditional workhorse — vaporizes papillomas, preserves underlying lamina propria
• KTP (532 nm): Highly selective for vascular feeding vessels (photoangiolytic) → destroys papilloma with superior voice outcomes → now preferred by many (Zeitels et al.)
• Pulsed KTP / 585 nm PDL (Pulsed Dye Laser): Angiolytic; less scarring
• Adjuvant therapies (when >4 surgeries/year):
  • Intralesional Cidofovir injection (off-label)
  • Bevacizumab (Avastin) injection — anti-VEGF (recent advance)
  • Interferon-alpha
  • HPV Vaccination (Gardasil) — preventive and possibly therapeutic role (recent)

Diagnosis of RRP (HPV 6/11)
         │
         ↓
STAGING (Derkay Staging Score)
         │
         ↓
SURGICAL EXCISION under Microlaryngoscopy
(KTP Laser preferred / CO₂ Laser)
         │
    ┌────┴────┐
    ↓         ↓
<4 ops/yr  ≥4 ops/yr
   │            │
Follow up    ADD ADJUVANTS:
regularly    Cidofovir / Bevacizumab
             Interferon / Vaccination
         │
         ↓
Tracheostomy (last resort — may spread disease)

C. Laser in Laryngeal Malignancy (Transoral Laser Microsurgery — TLM)

• No neck dissection scar for early glottic tumors
• Functional larynx preservation
• Shorter hospital stay
• Can be repeated if recurrence
• Avoids tracheostomy in most cases

5.4 Laser in Laryngeal Stenosis / Subglottic Stenosis

• Post-intubation subglottic stenosis (Cotton-Myer Grade I–II)
• Post-tracheostomy stenosis
• Idiopathic subglottic stenosis (women, autoimmune)
• Congenital subglottic stenosis

SUBGLOTTIC STENOSIS
         │
         ↓
 MICROLARYNGOSCOPY
         │
         ↓
CO₂ LASER: 3–4 RADIAL INCISIONS
at 12, 3, 6, 9 o'clock positions
(Divide fibrous scar)
         │
         ↓
DILATION (Jackson, Savary, or balloon)
         │
         ↓
OPTIONAL: Mitomycin C application
(Antifibrotic agent, 0.4 mg/mL for 4 min)
         │
         ↓
ENDOSCOPIC REASSESSMENT AT 6–8 WEEKS
         │
    ┌────┴────┐
    ↓         ↓
 Success   Failure / Grade III–IV
(Maintain)  → Open resection
             (Cricotracheal resection)

• Mitomycin C (MMC) application post-laser incisions reduces restenosis — key adjunct (Correa et al., Laryngoscope)
• Success rate for Grade I–II: 85–90%; Grade III: 50–60%
• Grade IV Cotton-Myer stenosis → open surgery preferred

5.5 Laser in Arytenoid Surgery — Bilateral Vocal Cord Paralysis

• Gold standard endoscopic management of bilateral abductor paralysis
• CO₂ laser used to excise arytenoid cartilage or posterior cord → widen glottis
• Preference: Unilateral posterior cordotomy (Dennis-Kashima procedure) — enlarges glottis by 3–4 mm while preserving voice
• Alternative: Bilateral posterior cordotomy / total arytenoidectomy
• Avoids permanent tracheostomy in many patients

5.6 Laser in Supraglottic Pathology

• Epiglottic cysts: CO₂/KTP laser marsupiliazation → prevents recurrence
• Supraglottic carcinoma (T1–T2): TLM supraglottic laryngectomy (Steiner) — organ preservation with oncological equivalence to open supraglottic laryngectomy
• Lingual tonsil hypertrophy: Diode/CO₂ laser reduction
• Vallecular cysts: CO₂ laser excision

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6. LASER SURGERY IN THE NOSE AND PARANASAL SINUSES

6.1 Inferior Turbinate Reduction (Laser Turbinoplasty)

• Surface ablation (CO₂): Epithelium + submucosal vaporization
• Interstitial shrinkage (Diode/Nd:YAG): Fiber inserted into submucosa → coagulates submucosal tissue → fibrosis → shrinkage; overlying mucosa preserved
• Submucosal diode (preferred recently): Better mucosa preservation, less crusting

CHRONIC NASAL OBSTRUCTION
         │
   Medical Rx failed
         │
         ↓
LASER TURBINOPLASTY
(Diode / CO₂ / KTP)
         │
    ┌────┴────────────┐
    ↓                  ↓
SURFACE ABLATION    INTERSTITIAL
(CO₂/KTP)          SHRINKAGE
Vaporizes mucosa    (Diode 980nm)
+ submucosa         Submucosal fiber
                    preserves mucosa
         │
         ↓
ADVANTAGES over traditional turbinectomy:
- Less bleeding
- Outpatient / local anesthesia
- Less crusting (interstitial method)
- Ciliary function preserved

6.2 Laser in Epistaxis (Hereditary Hemorrhagic Telangiectasia — HHT / Osler-Weber-Rendu)

• KTP / Nd:YAG laser: Photocoagulation of telangiectatic vessels
• Fiber passed through rigid/flexible endoscope
• Avoids nasal packing complications
• Multiple sessions often needed
• Superior hemostasis for small-vessel disease
• Bevacizumab combined with laser — recent advance for refractory HHT epistaxis

6.3 Laser in Choanal Atresia

• Ho:YAG / CO₂ laser: Perforation and enlargement of atretic plate
• Used for membranous (15%) type; bony type (85%) needs drilling but laser assists in soft tissue
• Transnasal endoscopic approach with laser drill-out → stenting post-op
• Laser reduces bleeding compared to cold instrumentation

6.4 Laser in Rhinophyma

• CO₂ laser resurfacing: Treatment of choice for rhinophyma (Rosacea-related nasal skin hypertrophy)
• Layer-by-layer vaporization under local anesthesia
• Precise depth control → excellent cosmetic outcome
• Less scarring vs. dermabrasion / cold scalpel

6.5 Laser in Nasal Tumors / Sinus Tumors

• Laser-assisted endoscopic resection of inverted papilloma, angiofibroma (hemostasis during FESS)
• KTP for intraoperative hemostasis during FESS
• PDT for early-stage nasal malignancy

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7. LASER SURGERY IN THE EAR (OTOLOGY)

7.1 Laser Stapedotomy / Stapedectomy (Otosclerosis)

OTOSCLEROSIS (Conductive Hearing Loss)
          │
          ↓
UNDER GA / Local Anesthesia
Endaural / Permeatal approach
          │
          ↓
Tympanomeatal flap raised
          │
          ↓
Stapedial tendon divided (scissors/laser)
          │
          ↓
LASER (KTP / CO₂) applied to footplate center
          │
          ↓
Fenestration created (0.6–0.8 mm diameter)
          │
          ↓
Prosthesis placed (Teflon piston / Nitinol)
          │
          ↓
Connective tissue seal around prosthesis
          │
          ↓
Flap repositioned → ABG closure expected

• Precise footplate fenestration — no fracture, no plunging risk
• Less perilymph aspiration → reduced sensorineural loss risk
• Better hemostasis (vaporizes mucosal vessels)
• Safer for obliterative otosclerosis
• Less mechanical trauma to inner ear
• "Floating footplate" risk minimized

7.2 Laser in Cholesteatoma Surgery

• CO₂ / Er:YAG laser for dissection of cholesteatoma from ossicular chain and labyrinthine bone
• Particular advantage: Dissection around facial nerve, stapes, oval window
• Vaporizes matrix without mechanical traction → reduces risk of labyrinthine fistula
• Canal wall down / canal wall up tympanomastoidectomy assisted by laser
• Reduces risk of facial nerve injury due to precision

7.3 Laser in Tympanoplasty / Myringoplasty

• CO₂ laser for tympanic membrane perforations:
  • Freshening perforation margins (without scissors)
  • Myringotomy (CO₂ laser myringotomy — "Laser Assisted Myringotomy" — LAML)
  • Balloon replacement: Laser-created myringotomy stays patent longer (6–8 weeks) vs conventional (<1 week) → avoids grommet in some OME cases

7.4 Laser Myringotomy (LAML) in Otitis Media with Effusion (OME / Glue Ear)

• CO₂ laser creates a precise, clean myringotomy
• Healing delayed due to precise thermal tissue effect → patent 2–8 weeks
• Drains effusion; may avoid grommet insertion in mild-moderate cases
• Office procedure under topical anesthesia in adults/cooperative children
• Recent advance: Laser-assisted pressure equalization tube (LAPETM) — remains patent longer

7.5 Laser in Acoustic Neuromas (Vestibular Schwannoma)

• CO₂ / Nd:YAG used as adjuncts during microsurgical removal
• Shrinks tumor within capsule → facilitates dissection from facial nerve
• Less traction → better facial nerve outcomes
• Used in translabyrinthine, middle fossa, and retrosigmoid approaches

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8. LASER IN THE PHARYNX, TONSIL, AND ADENOID

8.1 Laser Tonsillectomy

1. Laser Tonsillectomy (full): CO₂ / KTP / Diode laser replaces cold dissection
2. Laser Tonsil Ablation (LTA): Partial cryptolysis with Nd:YAG/Diode → for cryptic tonsils/halitosis/tonsilloliths

GA / Local (office-based)
         │
         ↓
Tonsil grasped / retracted
         │
         ↓
CO₂ or Diode laser dissects peritonsillar space
         │
         ↓
Lower pole divided → Specimen out
         │
         ↓
Hemostasis with same laser
         │
         ↓
Post-op: Less pain (nerve coagulation) / Less
         bleeding vs conventional dissection

• Reduced intraoperative hemorrhage
• Faster procedure
• Less postoperative pain (coagulates sensory nerve endings)
• Reduced scarring — outpatient

• Risk of delayed hemorrhage (eschar separation, Day 5–10)
• Higher cost
• Risk of airway fire if not careful
• Not universally superior to COBLATION or cold dissection

8.2 Laser-Assisted Uvulopalatoplasty (LAUP)

LOCAL ANESTHESIA (awake patient)
         │
         ↓
CO₂ Laser removes uvula and trims soft palate
         │
         ↓
2 vertical channels in soft palate
+ uvula reshaped/amputated
         │
         ↓
3–5 sessions (monthly) until snoring resolves
or Single session under GA
         │
         ↓
Scar contracture tightens palate → less vibration

• 70–80% reduction in snoring intensity
• Not effective for moderate–severe OSA → CPAP or UPPP preferred
• Long-term results inferior to UPPP (uvulopalatopharyngoplasty)
• Current role: Mild OSA + snoring only + well-selected patients

8.3 Laser in Pharyngeal/Base of Tongue Surgery

• TLM for oropharyngeal carcinoma (TLOCP): Transoral laser microsurgery for base of tongue, tonsil carcinoma (p16+/HPV+) T1–T2
• Comparable oncological outcome to open and robotic approaches in early stages
• Diode/CO₂/Nd:YAG for tongue base reduction in OSA

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9. LASER IN THE ORAL CAVITY AND SALIVARY GLANDS

9.1 Oral Cavity Lesions

9.2 Salivary Gland Pathology

• Salivary gland endoscopy (Sialoendoscopy) + Laser: Ho:YAG / pulsed dye laser for salivary stone (sialolithiasis) fragmentation
• Intraductal lithotripsy via sialoscope → avoids gland excision
• Diode laser for intraductal stenosis dilatation
• Recent advance: Combined sialoendoscopy + extracorporeal shock wave lithotripsy (ESWL) + intracorporeal laser lithotripsy

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10. LASER IN HEAD AND NECK SURGERY (ONCOLOGY)

10.1 Transoral Laser Microsurgery (TLM) — Overall Oncology Role

• Glottic carcinoma: T1a, T1b, T2 (selected)
• Supraglottic: T1, T2
• Oropharynx: T1, T2 (tonsil, BOT, soft palate)
• Hypopharynx: T1–T2 pyriform sinus (selected)
• Oral cavity: T1, T2

1. The tumor can be cut through — frozen sections from margins
2. Multiple piece-meal resections with clear margins superior to one-block resection with positive margins
3. Preserve laryngeal framework
4. Combine with selective neck dissection for N+ disease

T1a Glottic Carcinoma
         │
         ↓
MDT Discussion
         │
    ┌────┴────────────────────┐
    ↓                          ↓
TLM (CO₂ Laser)           Radiotherapy
Cordectomy Type I–IV       (55–65 Gy)
         │                     │
         ↓                     ↓
  Local control          Local control
   90–95%                  90–95%
  Voice: good             Voice: better
  Duration: shorter        Duration: 6 weeks
  Retreatable: YES         Retreatable: limited
         │
         ↓
Margin positive → Revision TLM / Add RT

10.2 Photodynamic Therapy (PDT) in ENT Malignancy

PHOTOSENSITIZER (IV) → Taken up by tumor cells
          │
   72–96 hrs later
          │
LASER LIGHT activation (630 nm for mTHPC/Foscan;
                         630 nm for porfimer/Photofrin)
          │
          ↓
   SINGLET OXYGEN generation
          │
          ↓
   TUMOR CELL DESTRUCTION
   (Apoptosis + Necrosis + Vascular shutdown)

• Recurrent superficial oral cavity malignancy
• Nasopharyngeal carcinoma (surface recurrence)
• Early glottic carcinoma (salvage)
• Laryngeal papillomatosis (adjuvant)
• Palliative — advanced airway/pharyngeal tumors

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11. LASER IN PEDIATRIC ENT

Supraglottoplasty for Laryngomalacia:

SEVERE LARYNGOMALACIA
(stridor + feeding difficulties + FTT)
          │
          ↓
MICROLARYNGOSCOPY
          │
          ↓
CO₂ Laser division of:
- Aryepiglottic folds (bilateral/unilateral)
- Redundant arytenoid mucosa
          │
          ↓
SUCCESS: 90% resolution of symptoms
(Avoids tracheostomy in most cases)

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12. LASER IN THYROID AND NECK

12.1 Laser Thyroid Ablation

• Percutaneous Laser Ablation (PLA): Nd:YAG / Diode fiber inserted under ultrasound guidance into thyroid nodule
• Thermal coagulation → nodule shrinkage (50–75% volume reduction at 12 months)
• Indication: Benign, cytologically confirmed cold nodules causing cosmetic/compressive symptoms in poor surgical candidates
• Recent advance (RGUHS/AIIMS curriculum): Radiofrequency ablation (RFA) and laser ablation now recommended by European Thyroid Association (ETA) guidelines 2020

12.2 Laser in Neck / Lymphatic Malformations

• Nd:YAG interstitial laser for cystic hygroma / lymphatic malformation
• Alternative to sclerotherapy (OK-432) and surgery
• Image-guided percutaneous insertion

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13. COMPARISON OF LASERS — QUICK REFERENCE TABLE

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14. RECENT ADVANCES (2018–2024)

1. Blue Diode Laser (445 nm, Orca / Flexilas system): Highly selective for hemoglobin (photoangiolytic) → excellent for laryngeal and pharyngeal vascular lesions; flexible fiber delivery; office-based procedures
2. Thulium Fiber Laser (TFL, 1,940 nm): High water absorption, pulsed, flexible fiber → precise cutting; increasingly used for laryngeal surgery
3. LAUP modifications with Radiofrequency + Laser (combo): Better outcomes for OSA
4. Laser-Assisted Drug Delivery (LADD): Fractional CO₂ laser creates microchannels in skin/mucosa → enhanced drug penetration for topical agents
5. Bevacizumab + KTP laser for RRP: Anti-VEGF + angiolytic laser → decreased recurrence frequency (Zeitels, Harvard, 2019)
6. Sialoendoscopy with intracorporeal holmium laser lithotripsy — gland-preserving approach for sialolithiasis
7. Image-guided percutaneous laser thyroid ablation — endorsed by ETA 2020 guidelines
8. Narrow Band Imaging (NBI) + Laser: NBI identifies mucosal vasculature changes in dysplasia → guides targeted KTP laser treatment (Farneti et al.)
9. Robotic-assisted laser surgery: Da Vinci robot with integrated laser for pharyngolaryngeal tumors
10. Artificial Intelligence (AI) guided laser dosimetry: Real-time tissue feedback systems

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15. CONTRAINDICATIONS OF LASER SURGERY IN ENT

• Coagulopathy uncorrected
• Inaccessible lesion
• Airway fire risk (cannot secure safe airway)

• Lesion adjacent to critical structures requiring margin-negative open resection
• Advanced malignancy (T3–T4) — open surgery preferred
• Patient unable to cooperate for office-based procedures
• Lack of trained personnel / equipment
• Poor visibility in surgical field

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16. COMPLICATIONS OF LASER SURGERY IN ENT

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17. SUMMARY FLOWCHART — LASER SELECTION IN ENT

ENT LESION REQUIRING LASER
           │
     ┌─────┴──────────────────────────────┐
     │                                     │
  LARYNX                              NOSE / SINUSES
     │                                     │
  ┌──┴──────────────────┐             Turbinate → DIODE (interstitial)
  │                      │             Epistaxis HHT → KTP
Rigid (Suspended         │             Rhinophyma → CO₂
laryngoscopy)            │             Choanal atresia → Ho:YAG
     │                   │
  CO₂ laser          KTP/Blue
  (cordectomy,        diode (fiber,
  RRP, stenosis,      vascular,
  arytenoid)          angiolytic)
                          │
                    Office-based
                    transnasal / TVC
     │
  EAR
     │
  ┌──┴─────────────────────────────┐
  │                                 │
Stapedotomy                    Cholesteatoma
KTP / CO₂ / Argon              CO₂ / Er:YAG
     │
OROPHARYNX / ORAL CAVITY
     │
CO₂ TLM (malignancy, benign)
Diode (tonsil, LAUP)
     │
SALIVARY GLAND (stones)
Ho:YAG sialoendoscopy

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18. EXAMINATION TIPS (RGUHS 50-Mark Pattern)

1. Introduction + historical note (2 marks)
2. Physics of laser + laser-tissue interactions (6 marks)
3. Types of lasers in ENT (table) (4 marks)
4. Safety (4 marks)
5. Laser in Larynx (largest section) — RRP, cordectomy, TLM, stenosis, arytenoid (12 marks)
6. Laser in Nose/Ear/Pharynx/Oral cavity/Neck (10 marks)
7. Complications (4 marks)
8. Recent advances (4 marks)
9. Diagrams / flowcharts (drawn in exam) (4 marks)

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KEY REFERENCES

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Note on Image Generation: The image generation service has reached its monthly plan limit. The diagram above (laser approaches for vocal cord lesions) is retrieved from the PMC clinical database. For your exam, practice drawing the following diagrams by hand: (1) Laser system components, (2) Laser-tissue interaction zones, (3) ELS Cordectomy classification, (4) Cotton-Myer subglottic stenosis grading, (5) Laser stapedotomy steps, (6) LAUP technique.

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