Comprehensive Study Guide: Laryngeal Anatomy, Physiology, and Pathology

Basic Laryngeal Terminology & Definitions

• Dysphonia: A descriptive medical term indicating a functional or organic disorder of voice production.
• Hoarseness: A subjective patient-reported term referring to an altered, harsh, or weak voice quality.
• Vocal Quality Parameters: Voice changes associated with laryngeal dysfunction include:
  • Breathy voice
  • Harsh voice
  • Tremulous voice
  • Weak voice
  • Reduction to a whisper
  • Vocal fatigue (progressive voice deterioration with use)

Anatomical Framework of the Larynx

• Skeleto-Membranous Framework: The larynx is a complex organ extending vertically from the tip of the epiglottis down to the inferior border of the cricoid cartilage.

• Laryngeal Cartilages:
  • Unpaired Cartilages:
  • Thyroid Cartilage: Shield-like hyaline cartilage structure composed of two lateral laminae meeting anteriorly at the laryngeal prominence ("Adam's Apple"). Features superior and inferior horns (cornua), superior thyroid notch, oblique line, and superior/inferior tubercles. Undergoes calcification with age.

- **Cricoid Cartilage**: Signet ring-shaped hyaline cartilage comprising a posterior broad lamina and an anterior narrow arch. It is the **only complete skeletal ring** surrounding the entire airway. Undergoes calcification with age.
- **Epiglottis**: Leaf-like elastic cartilage structure positioned superiorly behind the tongue base. Attached to the thyroid cartilage via the thyroepiglottic ligament, to the hyoid bone via the hyoepiglottic ligament, and connected to the tongue via the median and lateral glossoepiglottic folds forming the valleculae. Does not undergo calcification.

• Paired Cartilages:
  • Arytenoid Cartilages: Pyramidal-shaped hyaline cartilages located on the upper border of the cricoid cartilage lamina. Each arytenoid features an apex, an anterior vocal process (attachment for vocal ligament), and a lateral muscular process (attachment for intrinsic muscles).
  • Corniculate Cartilages: Small elastic cartilaginous nodules sitting atop the apices of the arytenoid cartilages.
  • Cuneiform Cartilages: Small rod-shaped elastic cartilages embedded within the aryepiglottic folds anterior to the corniculate cartilages.
• Hyoid Bone: U-shaped neck bone located superiorly to the larynx. Although not part of the larynx, it serves as an anchor for laryngeal membranes and extrinsic musculature while shielding the upper epiglottis.

• Laryngeal Joints:

  • Cricothyroid Joint: A synovial joint between the inferior horn of the thyroid cartilage and the cricoid cartilage. Functions via a hinge-like pivoting motion that tilts the thyroid cartilage anteriorly, lengthening and tensing the vocal folds.
  • Cricoarytenoid Joint: A synovial joint between the base of the arytenoid cartilage and the superior border of the cricoid lamina. Enables complex rocking, sliding, and rotational movements necessary for vocal fold adduction and abduction.

• Laryngeal Membranes & Ligaments:

  • Thyrohyoid Membrane: Extends from the upper border of the thyroid cartilage to the hyoid bone; contains lateral thickened borders that may house small triticeal cartilages. Pierced by the internal branch of the superior laryngeal nerve and superior laryngeal artery.
  • Quadrangular Membrane: Submucosal elastic sheet extending between the lateral border of the epiglottis and the arytenoid cartilage.
  • Upper free border thickened $\rightarrow$ forms the Aryepiglottic Fold.
  • Lower free border thickened $\rightarrow$ forms the Vestibular Ligament (false vocal cord / vestibular fold).
  • Conus Elasticus (Triangular Membrane / Cricovocal Membrane): Submucosal elastic tissue extending upward from the cricoid ring.
  • Anterior median reinforcement $\rightarrow$ Median Cricothyroid Ligament.
  • Upper free superior border thickened $\rightarrow$ forms the Vocal Ligament (true vocal cord).

Cavity, Histology, and Vocal Fold Layers

• Laryngeal Mucosal Lining:

  • Stratified Squamous Epithelium: Covers regions subjected to mechanical friction, specifically the true vocal cords and aryepiglottic folds.
  • Ciliated Pseudostratified Columnar Epithelium: Covers all other regions of the respiratory tract lining from the trachea up to the aryepiglottic folds.

• Subdivisions of the Laryngeal Cavity:

  • Supraglottis: Extends from the tip of the epiglottis down to the laryngeal ventricle (above the true vocal cords). Includes epiglottis, aryepiglottic folds, arytenoids, false vocal cords, and ventricle.
  • Glottis: Comprises the true vocal folds, anterior commissure, and posterior commissure.
  • Subglottis (Infraglottic Space): Extends from the inferior mucosal surface of the true vocal folds down to the inferior border of the cricoid cartilage.

• Five Histological Layers of the True Vocal Fold:

1. Epithelium: Non-keratinized stratified squamous epithelium maintaining vocal fold shape.
2. Lamina Propria - Superficial Layer (Reinke's Space): Loose extracellular matrix with sparse elastic/collagen fibers; crucial for mucosal wave vibration.
3. Lamina Propria - Intermediate Layer: Rich in elastic fibers.
4. Lamina Propria - Deep Layer: Dense in collagen fibers.
   • Note: The intermediate and deep layers combined constitute the Vocal Ligament.
5. Vocalis Muscle (Thyroarytenoid Muscle): The main body/bulk of the true vocal fold.

Laryngeal Musculature

• Extrinsic Musculature: Responsible for moving the larynx as a whole superiorly or inferiorly.

• Depressors (Strap Muscles / Infrahyoid Group): Innervated by Ansa Cervicalis ($C_1 - C_3$):

  • Sternohyoid
  • Sternothyroid
  • Omohyoid
  • Thyrohyoid (innervated specifically by $C_1$ via CN XII)

• Elevators (Suprahyoid Group):

  • Geniohyoid (innervated by $C_1$ via CN XII)

  • Digastric (anterior belly: CN $V_3$; posterior belly: CN VII)

  • Mylohyoid (innervated by CN $V_3$)

  • Stylohyoid (innervated by CN VII)

  • Intrinsic Musculature: Controls movement of individual laryngeal cartilages to regulate vocal cord tension and airway opening.

• Sole Abductor (Opens Vocal Cords):
  • Posterior Cricoarytenoid (PCA): Rotates muscular process posteriorly, abducting vocal cords to open glottic airway.

• Adductors (Close Vocal Cords):
  • Lateral Cricoarytenoid (LCA): Pulls muscular process anteriorly, adducting vocal cords.

- **Transverse Arytenoid (Interarytenoid)**: Unpaired muscle bridging posterior surfaces of both arytenoids; approximates arytenoids to close glottis posterior gap.
- **Oblique Arytenoid**: Crosses posteriorly between arytenoids; extends into aryepiglottic fold.
- **Thyroarytenoid (TA)**: Pulls arytenoid anteriorly toward thyroid cartilage, shortening and relaxing the vocal fold.

• Tensor / Lengthener:
  • Cricothyroid (CT): Tilts cricoid arch upward or thyroid cartilage downward, lengthening and tensing vocal folds.

Neurovascular Supply & Pediatric Anatomy

• Nerve Supply: Derived entirely from the Vagus Nerve (CN X).

• Superior Laryngeal Nerve (SLN):
  • Internal Branch (Sensory): Provides sensory innervation to the laryngeal mucosa superior to true vocal cords (supraglottis & glottis). Travels alongside the superior laryngeal artery through the thyrohyoid membrane.
  • External Branch (Motor): Provides motor innervation exclusively to the Cricothyroid muscle.
• Recurrent Laryngeal Nerve (RLN):
  • Provides motor innervation to ALL intrinsic laryngeal muscles EXCEPT the cricothyroid.
  • Provides sensory innervation to the subglottis/infraglottic mucosa inferior to the vocal cords.
  • Asymmetric Course:

  - **Right RLN**: Arises in lower neck, loops under the Right Subclavian Artery, and ascends in the tracheoesophageal groove.
  - **Left RLN**: Arises in thorax, loops under the Arch of the Aorta deep/posterior to ligamentum arteriosum, and ascends in the left tracheoesophageal groove (longer, more vulnerable course).
- Terminal division occurs behind cricothyroid joint.

• Vascular Supply & Lymphatic Drainage:

  • Arterial Supply:
  • Superior Laryngeal Artery (branch of Superior Thyroid Artery from External Carotid).
  • Inferior Laryngeal Artery (branch of Inferior Thyroid Artery from Thyrocervical Trunk).
  • Venous Drainage: Superior and Inferior laryngeal veins emptying into internal jugular and brachiocephalic veins respectively.
  • Lymphatic Drainage:
  • Supraglottis (above vocal cords): Drains superiorly through thyrohyoid membrane to Upper Deep Cervical Lymph Nodes.
  • Subglottis (below vocal cords): Drains inferiorly to Lower Deep Cervical Lymph Nodes, pretracheal, and paratracheal nodes.
  • True Vocal Cords (Glottis): Contains virtually no lymphatic capillaries; minimal to no primary lymphatic drainage (explains low rate of early nodal metastasis in glottic cancer).

• Pediatric Airway Differences:

  • Neonates are obligate nasal breathers until approximately $2\,m/s^2$ months of age.
  • Epiglottis at birth is characteristically Omega ($\Omega$)-shaped.
  • High laryngeal position relative to cervical spine: positioned at level $C_1 - C_4$ in infants versus $C_4 - C_6$ in adults.
  • Narrowest portion of the pediatric airway is at the level of the subglottis (cricoid ring), unlike adults where the glottic opening is narrowest.

Physiology of the Larynx

• Primary Functions:

  1. Protection of Lower Air Passages (Most primitive & vital function):
  • Closure of laryngeal inlet (aryepiglottic sphincter).
  • Closure of glottis (true and false vocal cord adduction).
  • Cessation of respiration (swallowing reflex apnea).
  • Cough reflex: High subglottic air pressure generated against a closed glottis, followed by explosive opening and forced expiration.
  1. Respiration: Active abduction of vocal cords during inspiration by PCA muscle to optimize airway diameter.
  2. Phonation: Sound production via vocal fold vibration driven by exhaled airflow.

• Subsystems of Voice Mechanism:

• Air Pressure System: Comprises lungs, diaphragm, chest wall, and abdominal muscles. Supplies aerodynamic power/airflow.

• Vibratory System: Comprises true vocal folds within the larynx. Converts aerodynamic energy into a raw acoustic sound ("buzzy sound").

• Resonating & Modifying System: Comprises vocal tract resonators (pharynx, oral cavity, nasal cavity, chest). Amplifies and modifies sound.

• Articulators: Tongue, soft palate, lips. Shapes phonation into distinct speech phonemes.

• Three Components of Spoken Word: Voiced sound $\rightarrow$ Resonance $\rightarrow$ Articulation.

  • Vocal Fold Vibratory Mechanics & Physics:

• Bernoulli Effect & Mucosal Wave: Aerodynamic pressure drops as airflow velocity increases through the narrowed glottis, pulling vocal fold edges together in repetitive cycles. Mucosal wave travels vertically from inferior to superior.

• Fundamental Vibratory Frequencies:

  • Men: $\sim 110\,\text{cycles/second (Hz)}$ (lower pitch).
  • Women: $180 - 220\,\text{cycles/second (Hz)}$ (medium pitch).
  • Children: $\sim 300\,\text{cycles/second (Hz)}$ (higher pitch).

• Vocal Intensity (Loudness): Achieved by increasing subglottic pressure and amplitude of vocal fold vibration.

  • Laryngeal Sphincters:

• True vocal cord sphincter

• False vocal cord (vestibular) sphincter

• Aryepiglottic sphincter

Clinical Evaluation of Dysphonia

• Patient History:

  • Detailed characterization of dysphonia (onset, duration, progression, fluctuation, severity).
  • Associated symptoms: Upper respiratory tract infection (URTI), fever, cough, voice abuse/overuse (occupational demands e.g. teachers, singers), tobacco and alcohol exposure, dysphagia, odynophagia, aspiration, breathing difficulty (stridor/dyspnea), unintentional weight loss, gastroesophageal reflux disease (GERD) / laryngopharyngeal reflux (LPR), neck/chest trauma, prior surgical procedures (thyroid, neck, thoracic, intubation history), neck masses.

• Physical Examination & Diagnostic Techniques:

  • Comprehensive ENT and head & neck examination, including cervical lymph node palpation and cranial nerve testing.
  • Indirect Laryngoscopy: Performed using a laryngeal mirror. Patient must sit upright with neck flexed and head extended ("sniffing position") while the physician gently grasps the protruded tongue.

• Endoscopic Visualizations:

- **Flexible Fiberoptic Nasopharyngolaryngoscopy**: Transnasal examination allowing assessment of dynamic vocal fold motion during speech and quiet breathing.
- **Rigid Transoral Laryngoscopy**: High-definition zoomed visualization of vocal fold edge fine detail using 70° or 90° telescopes.

• Stroboscopy: Synchronization of flashing light with vocal fold frequency to analyze mucosal wave amplitude, symmetry, periodicity, and glottic closure patterns.
• Acoustic & Perceptual Voice Analysis.
• Direct Laryngoscopy: Performed in operating room under general anesthesia for direct operative visualization and biopsy.

Congenital Laryngeal Anomalies

• Laryngomalacia:
  • Definition: Flaccidity of supraglottic laryngeal tissues. Most common cause of congenital stridor in neonates and infants.

• Endoscopic Findings:

  • Inward collapse of shortened aryepiglottic folds into laryngeal inlet during inspiration.
  • Epiglottis curled/collapsed (classic Omega $\Omega$-shaped epiglottis).
  • Cuneiform/corniculate mucosa prolapsing into glottis.

• Clinical Features: Intermittent inspiratory stridor presenting in first weeks of life; worsens with feeding, crying, or supine positioning; improves when patient is placed in PRONE position.

• Diagnosis: History and awake flexible fiberoptic endoscopy.

• Management:

  • Observation: $90\%$ of cases resolve spontaneously by $18 - 24\,\text{months}$.

  • Surgical Intervention (Supraglottoplasty / Epiglottoplasty): Indicated for severe respiratory distress, cyanosis, apneas, feeding difficulty, cor pulmonale, or failure to thrive. Endoscopic division of short aryepiglottic folds. Tracheostomy reserved for failure cases.

  • Subglottic Stenosis:

• Definition: Airway lumen narrowing at the subglottic level due to incomplete embryonic recanalization or an abnormally small cricoid ring. Can also be acquired secondary to neonatal prolonged intubation.

• Histological Types: Membranous, Cartilaginous, Mixed.

• Cotton-Myer Grading System:

  • Grade I: $< 50\%$ luminal obstruction.
  • Grade II: $51\% - 70\%$ luminal obstruction.
  • Grade III: $71\% - 99\%$ luminal obstruction.
  • Grade IV: Complete obstruction ($100\%$, no detectable lumen).

• Clinical Features: Biphasic stridor, recurrent croup-like illnesses, dyspnea, failure to thrive.

• Diagnosis: Neck/chest radiographs, flexible/rigid endoscopy.

• Management:

  • Grades I & II: Conservative management or endoscopic interventions ($CO_2$ laser excision, cold knife incision, balloon dilation).

  • Grades III & IV: Open surgical reconstruction (Anterior Cricoid Split [ACS], Laryngotracheal Reconstruction [LTR] with cartilage grafting, Cricotracheal Resection [CTR]); Tracheostomy for airway security.

  • Laryngeal Web:

• Definition: Incomplete decanalization of the laryngeal lumen during embryonic development.

• Locations: Glottic (most common, typically anterior commissure), Supraglottic, Subglottic.

• Clinical Features: Weak/muffled cry at birth or aphonia, variable degrees of airway obstruction and stridor.

• Diagnosis: Flexible endoscopy.

• Management:

  • Asymptomatic / thin web: Observation or simple endoscopic lysis (laser or cold instruments).

  • Thick web: Open laryngofissure procedure with placement of a silastic keel + temporary tracheostomy.

  • Subglottic Hemangioma:

• Definition: Benign vascular lesion of the subglottic space. Most common vascular tumor of the infant lower airway.

• Association: Approximately $50\%$ of affected infants have concurrent cutaneous hemangiomas (especially in beard distribution).
• Histological Types: Capillary (tends to undergo spontaneous involution), Cavernous.
• Clinical Features: Asymptomatic at birth; develops biphasic stridor and barky cough around $2 - 6\,\text{months}$ as hemangioma undergoes rapid proliferative phase.
• Diagnosis: Endoscopy demonstrating a smooth, compressible, reddish-blue subglottic submucosal mass.
• Management: Observation, systemic corticosteroids, oral Propranolol (first-line medical pharmacotherapy), or $CO_2$ laser ablation.

Traumatic Conditions and Vocal Abuse Lesions

• Laryngeal Trauma:
  • Mechanisms: Direct blunt neck blows, penetrating open injuries, thermal/inhalation burns, chemical corrosive burns, foreign body aspiration.
  • Intubation Injuries:

- Etiology: Prolonged intubation, traumatic/blind intubation, oversized endotracheal tube placement.
- Sequence of Pathology: Mucosal abrasion/ischemia $\rightarrow$ ulceration $\rightarrow$ granulation tissue formation $\rightarrow$ **Intubation Granuloma** (typically posterior vocal process of arytenoid) $\rightarrow$ healed fibrous nodule / interarytenoid adhesion / subglottic stenosis.
- Symptoms: Hoarseness, dyspnea, stridor.
- Treatment: Prevention (proper sizing), voice rest, anti-reflux therapy, endoscopic laser/surgical removal.

• Benign Vocal Fold Lesions (Phonotrauma):
  • Vocal Fold Nodules ("Singer's Nodules"):

- **Characteristics**: Bilateral, symmetric, callus-like inflammatory thickenings.
- **Location**: Junction of the **anterior 1/3 and middle 1/3** of true vocal folds (point of maximum mechanical impact).
- **Etiology**: Chronic vocal abuse/overuse.
- **Management**: **First-line treatment is Speech/Voice Therapy**. Surgical micro-excision (microlaryngoscopy) is reserved for persistent, fibrotic nodules failing conservative therapy.

• Vocal Fold Polyp:

- **Characteristics**: Usually **unilateral**, smooth, pedunculated or sessile mass along the free edge.
- **Pathology**: Mucoid or hemorrhagic/gelatinous tissue accumulation in Reinke's space.
- **Location**: Free edge of middle and anterior 1/3 of vocal fold.
- **Etiology**: Acute phonotrauma (screaming episode) or smoking.
- **Management**: Phonosurgical excision via microlaryngoscopy.

• Vocal Fold Cyst:

- **Characteristics**: Unilateral, encapsulated fluid-filled or epidermoid sac embedded within Reinke's space.
- **Types**: Congenital epidermoid cyst, Mucus retention cyst.
- **Management**: Surgical micro-flap excision and cyst enucleation.

• Reinke's Edema (Polypoid Corditis):

- **Characteristics**: Diffuse, bilateral fluid accumulation and ballooning of Reinke's space (superficial layer of lamina propria).
- **Etiology**: Strong causal link with **chronic heavy smoking**, vocal abuse, and laryngopharyngeal reflux. Produces a abnormally low-pitched, husky voice.
- **Management**: Smoking cessation (essential), anti-reflux therapy, voice rest, longitudinal vocal fold incision and fluid aspiration/surgical debulking.

• Laryngocele:
  • Definition: Air-filled abnormal dilation of the laryngeal saccule (appendix of the laryngeal ventricle) communicating directly with the laryngeal lumen.
  • Etiology: Congenital or acquired (occupations with elevated intra-laryngeal pressure, e.g., trumpet players, glassblowers).
  • Types:
    • Internal: Confined inside the thyroid cartilage matrix within the laryngeal lumen.
    • External: Extends superiorly through the thyrohyoid membrane presenting as a compressible lateral neck mass.
    • Combined: Features both internal laryngeal and external cervical components.
  • Management: Endoscopic marsupialization or external cervical surgical excision.

Vocal Cord Immobility & Paralysis

• Etiology:

  • Adult Causes:
  • Iatrogenic Trauma: Thyroidectomy / neck surgery, thoracic surgeries (lung resection, aortic repair), skull base procedures, carotid endarterectomy, traumatic intubation.
  • Non-Iatrogenic Trauma: Blunt or penetrating neck trauma.
  • Neoplasms: Thyroid carcinoma, esophageal carcinoma, lung carcinoma, mediastinal masses, glomus/skull base tumors.
  • Medical Disorders: Cardiovascular conditions (Ortner's syndrome / atrial enlargement, aortic aneurysm), central/peripheral neurological diseases, granulomatous diseases, neurotoxic chemotherapy (e.g. vincristine).
  • Idiopathic.
  • Pediatric Causes: Arnold-Chiari malformation, birth trauma, hydrocephalus.

• Clinical Manifestations: Dysphonia (breathy voice quality), choking, aspiration of liquids, weak cough, stridor (prominent in bilateral paralysis).

• Vocal Cord Positions: Median, Paramedian, Cadaveric (lateral).

• Management Strategies:

  • Unilateral Paralysis (Medialization Procedures):

- **Vocal Cord Injection Augmentation**: Temporary or permanent injectables (Gelfoam, Fat, Collagen, Teflon, Hyaluronic acid) into lateral vocal fold to push medial edge.
- **Thyroplasty Type I (Isshiki Medialization)**: Surgical creation of a window in the thyroid cartilage lamina to insert a silastic or titanium wedge pushing the paralyzed fold medially.

• Bilateral Paralysis in Adduction (Airway Opening Procedures):

- **Posterior Cordotomy**: Endoscopic resection of posterior vocal cord.
- **Arytenoidectomy**: Laser ablation or surgical excision of the arytenoid cartilage to widen posterior glottis.
- **Tracheostomy**: Indicated for immediate emergency airway protection.

Inflammatory and Infectious Laryngeal Diseases

• Acute Viral Laryngitis:

  • Etiology: Rhinovirus, Parainfluenza virus, Influenza.
  • Symptoms: Dysphonia, fever, dry cough, hoarseness.
  • Management: Conservative (voice rest, hydration, humidified air, analgesics).

• Acute Epiglottitis (Supraglottitis):

  • Etiology: Haemophilus influenzae type b (Hib); Streptococcal and Staphylococcal species. Classically affects children aged $2 - 6\,\text{years}$, though adults can be affected.

• Symptoms: Rapid onset of high fever, severe dysphagia, odynophagia, drooling, dyspnea, "sniffing position" / tripod posture, absence of cough, muffled "hot potato" voice.

• Diagnosis: Lateral neck radiograph revealing the classic "Thumbprint sign".

• Critical Caution: DO NOT examine the throat using a tongue depressor in the ER due to high risk of triggering fatal laryngospasm.

• Management: Secure airway via endotracheal intubation in the Operating Room (OR); administer intravenous antibiotics (3rd generation Cephalosporins) and intravenous corticosteroids.

  • Croup (Acute Laryngotracheobronchitis):

• Primary Site: Subglottis.

• Etiology: Parainfluenza virus types 1-3. Peak incidence in children aged $1 - 5\,\text{years}$.

• Symptoms: Biphasic stridor, low-grade fever, characteristic barking / brassy seal-like cough, hoarseness, absence of dysphagia.

• Diagnosis: Anteroposterior neck radiograph demonstrating subglottic mucosal narrowing known as the "Steeple sign".

• Management: Humidified oxygen, nebulized racemic epinephrine, systemic or inhaled corticosteroids (Dexamethasone).

  • Diphtheritic Laryngitis:

• Etiology: Corynebacterium diphtheriae.

• Symptoms: Barking cough, stridor, dysphonia, fever, and formation of an adherent greyish-white pseudomembrane over laryngeal/pharyngeal mucosa.

• Management: Prompt Diphtheria Antitoxin injection, systemic Penicillin or Erythromycin, oxygen, tracheostomy if airway obstruction occurs.

  • Fungal Laryngitis:

• Occurrence: Immunocompromised individuals, patients on prolonged broad-spectrum antibiotics or inhaled corticosteroids.

• Etiology: Candida albicans, Aspergillus.

• Symptoms: Persistent dysphonia, cough, odynophagia, white mucosal plaques.

• Management: Systemic or topical antifungal agents (e.g., Fluconazole, Nystatin).

  • Recurrent Respiratory Papillomatosis (RRP):

• Demographics: $2/3$ of cases manifest before age 15 (Juvenile RRP); can also present in adults (Senile/Adult RRP).

• Etiology: Human Papillomavirus (HPV types 6 and 11 most common, benign); HPV 16 and 18 associated with dysplastic and malignant transformation risk.

• Risk Factors: Young first-time mothers with active maternal condyloma acuminata at time of vaginal delivery.
• Gross Appearance: Exophytic, wart-like, friable epithelial lesions resembling clusters of grapes.
• Symptoms: Progressive hoarseness, stridor, airway compromise.
• Management: Surgical debulking via $CO_2$ laser excision or microdebrider. Adjunctive medical therapy includes intralesional Cidofovir, Acyclovir, or Interferon.

Malignant Neoplasms of the Larynx

• Epidemiology & Histology:
  • Represents $1\% - 5\%$ of all systemic malignancies.
  • Virtually all ($>95\%$) are Squamous Cell Carcinomas (SCC).

• Risk Factors: Heavy tobacco smoking, chronic alcohol consumption, radiation exposure.

• Clinical Symptoms: Progressive persistent hoarseness, dysphagia, odynophagia, aspiration, stridor, dyspnea, weight loss, cervical lymphadenopathy.

• Anatomic Subsite Classification:

  • Supraglottic Cancer:
  • Represents $30\% - 40\%$ of laryngeal cancers.
  • High propensity for early bilateral nodal metastasis ($25\% - 75\%$) due to dense, rich lymphatic plexus.
  • Glottic Cancer:
  • Represents $50\% - 75\%$ of laryngeal cancers (most common).
  • Presents early with hoarseness.
  • Low incidence of regional nodal metastasis due to sparse glottic lymphatics.
  • Subglottic Cancer:
  • Rare ($<2\% - 5\%$).
  • Presents late with airway compromise/stridor.
  • Regional nodal metastasis rate \sim 20\%$.\n\n- **Treatment Modalities**:\n - Early stage (T1-T2): Definitive Radiotherapy or Conservative Partial Laryngectomy (e.g. transoral endoscopic CO_2 laser resection, hemilaryngectomy).\n - Advanced stage (T3-T4): Total Laryngectomy + Neck Dissection \pm$$ Postoperative Radiotherapy or Chemoradiotherapy.