Upper Airway

Laryngeal Development

larynx, trachea, bronchi and lungs begin development at 4 weeks; definite larynx present by 10 weeks

laryngotracheal groove develops into laryngotracheal diverticulum

tracheoesophageal septum separates ventral foregut (laryngotracheal tube) from dorsal portion (primordium of oropharynx and esophagus)

recanalization of closed epithelial lamina

upper larynx develops from branchial arches 3 and 4; lower larynx develops from branchial arch 6

Laryngeal Anatomy

three anatomical regions: Supraglottic, Glottic, and Subglottic

Cartilages:

Thyroid (median elevation called the laryngeal prominence, a.k.a. Adam’s apple)

Cricoid (most inferior of the cartilages of the larynx)

Arytenoid (2, attached to vocal ligaments)

Corniculate (2)

Cuneiform (2)

Epiglottis (made of elastic cartilage)

Bone – Hyoid

Suspensory membranes and ligaments

Muscles:

Intrinsic – opens and closes the glottis; posterior cricothyroid abducts; others open
Extrinsic – move larynx when swallowing so food moves posteriorly down esophagus

Pediatric vs. Adult Anatomy

Size – child larynx is 1/3 size of adult, but arytenoid is adult size at birth; vocal process 30% of child vocal cord,

50% of adult vocal cord - narrowest part of airway: subglottis (cricoid lumen) in child, glottis in adult

Location of glottis – level C4 at birth; level C5-C6 during adolescence; level C7 in adult

Configuration and tissue consistency – epiglottis short and small/omega shaped in child; looser submucosal tissue; cartilage more cellular

Laryngeal Functions

Respiration – synchronous abduction of the true vocal cords with inspiration and expiration

Phonation – synchronous approximation, tensing, and vibrating of the true vocal cords

Sphincter – protection of the airway by synchronous adduction of true and false vocal cords

Prevent aspiration, permit cough

Increase efficiency of lifting, micturition, defecation, and parturition by Ý thoracic and abdominal pressure

Laryngeal dysfunction

Respiration – a. dyspnea; b. tachypnea; c. apnea; d. retractions

Stridor – harsh vibratory sounds associated with airway obstruction Þ often can localize abnormality by sound; caused by tumor, foreign body, inflammation

inspiratory – supraglottic to subglottic lesion
expiratory – peripheral bronchial tree
combined – tracheobronchial tree

Phonation – a. dysphonia; b. hoarseness; c. aphonia

Sphincter – a. aspiration; b. weak or absent cough

Laryngeal Examination

Indirect mirror laryngoscopy

Flexible fiberoptic nasopharyngolaryngoscopy (can be used in office)

Radiology – 1. soft-tissue x-ray; 2. CT; 3. MRI

Flow-Volume Spirometry (Physiologic functioning test)

Variable extrathoracic obstruction – see flattening of inspiratory curve

Direct Laryngoscopy – can spread vocal folds apart; use suction

Microlaryngoscopy – microscopes often facilitate surgery

Congenital Disorders

Laryngomalacia – most common cause of congenital laryngeal stridor (60%)

Laryngeal function

Respiration – inspiratory stridor
Phonation – normal (normal cry in children)
Sphincter – normal

Pathophysiology: Supraglottic structures fall into laryngeal inlet with inspiration (arytenoids are primary factor)

Etiology unclear – possible neuromuscular immaturity

Worse with crying and/or supine position (causes closure of the airway); Males > females

Resolves spontaneously by 18-24 months; up to 20% associated airway anomalies, 5-10% with subglottic stenosis

Therapy – observation in most cases; laser release of aryepiglottic fold; < 5% require tracheotomy

Laryngeal web and Subglottic Stenosis

Laryngeal function

Respiration – slight to severe obstruction
Phonation – mild to severe dysphonia
Sphincter – normal

Etiology – failure to recanalize epithelial lamina

Treatment options depend on web thickness (therapy is not always necessary)

laser lysis
resect and stent to keep tissue from reforming
cricoid split and widen with interposed rib graft
50% of congenital and 10% of acquired laryngeal web and subglottic stenosis do not require surgery

Paralytic Disorders

Unilateral true vocal cord paralysis – left is more often affected than right (due to course of recurrent laryngeal n)

paralyzed cord remains in paramedian position; air can escape through causing "breathy voice"
non-paralyzed cord may compensate by moving past the midline to meet the paralyzed cord

Laryngeal function

Respiration – mild to moderate obstruction
Phonation – mild to moderate dysphonia
Sphincter – normal to aspiration; weak cough

Etiology

child: forceps - breech delivery (stretched neck); Arnold-Chiari malformations; cerebral agenesis/mental retardation; Cardiac abnormalities and/or surgery – damage to the laryngeal nerve
adult: idiopathic (most likely viral neuropathy), iatrogenic (thyroid, carotid, spine surgery), malignancy (pulmonary, thyroid, CNS, head and neck; most common cause), neurologic - CVA

Treatment –do nothing (spontaneous recovery or compensation); speech therapy; vocal cord injection (push paralyzed cord to midline with teflon, gelfoam, fat); vocal fold re-innervation; thyroplasty with cartilage, silastic (vocal cord medialization)

Bilateral True Vocal Cord Paralysis

Laryngeal function

Respiration – moderate to severe obstruction
Phonation – moderate dysphonia
Sphincter – normal to moderate impairment of airway protection and cough

Etiology – iatrogenic – thyroid surgery (most common), malignancy, trauma, idiopathic, neurologic

Treatment – restrict activity; partial vocal cord resection or arytenoidectomy with laser; vocal cord lateralization; tracheotomy

Infectious/Inflammatory Disorders

Acute Epiglottis (Supraglottitis) – infection of the epiglottic structures

Laryngeal function

Respiration – dyspnea, inspiratory stridor
Phonation – hot potato voice
Sphincter – depressed function

Clinical picture – 3-6 year old: cherry red epiglottis; rapid onset, toxic child, febrile; sniffing position, drooling; lethargic secondary to hypercarbia; elevated WBC, positive blood culture for H flu, type B

adults present with severe sore throat and stridor

Epidemiology changing due to HIB vaccine – marked ß in frequency

Radiology – only if patient stable because airway can close rapidly

Treatment – O₂ and rapid airway management in OR; Ceftriaxone and/or other antibiotic for H. flu; endotracheal intubation until airway cellulitis resolved (48 to 96 hours); tracheotomy rarely used currently

Acute Laryngeal Tracheobronchitis (Croup) – subglottic inflammation

Laryngeal function

Respiration – inspiratory stridor, barking cough
Phonation – normal to hoarse
Sphincter – normal to depressed

Clinical picture – 6 months to 3 year old child; gradual onset with URI x several days preceding onset

Etiology – viral (usually parainfluenza virus)

Treatment:

supportive care
antibiotics for pulmonary infiltrates
cool mist humidity
endotracheal intubation if not improved
steroids
tracheotomy (rarely used currently)
racemic epinephrine inhalations

Chronic Laryngitis – vocal nodules, polyps, granulomas; alter only phonatory function

Therapy: eliminate instigating factors – cigarettes, voice abuse, paranasal sinus drainage, gastroesophageal reflux

microlaryngeal removal of lesion

Laryngeal Neoplasms – Benign

Laryngeal papilloma (respiratory papillomatosis)

Laryngeal function

Respiration – normal to severe obstruction
Phonation – hoarse to aphonic
Sphincter – normal to aspiration

Clinical picture

weak cry or hoarseness in child; can present with airway obstruction
generally no respiratory tract symptoms at birth; develop within a few months to years

Etiology – > 60% with history of exposure to maternal vaginal condylomata; HPV types 8 and 11 most common

Therapy:

microlaryngoscopy and periodic laser removal in advance of airway obstruction
limited role for interferon
avoid tracheotomy if possible to limit distal spread
80% of juvenile papillomas (and 36% of adult) recur

Laryngeal Neoplasm – Malignant

Laryngeal cancer (uncommon compared to lung cancer)

Laryngeal function

Respiration – normal to obstructed airway
Phonation – normal to hoarse
Sphincter – normal to aspiration and restricted cough

Squamous cell cancer (SCC) – 95% of malignant lesions of larynx – 15,000 new cases and 5,000 deaths each year

M > F; 6-7th decade most common; Risk factors – smoking, alcohol, (genetics?)
Sites/frequency of laryngeal SCC: Glottic - 70%; Supraglottic - 25%; Subglottic - 5%

Tumor Staging:

I-II: highly variable 80-95% 5 year survival

III-IV: poor prognosis 10-50% 5 year survival

Treatment:

Microlaryngoscopy and excision of lesions with or without laser
Partial laryngectomy (with preservation of laryngeal functions), or total laryngectomy
Laryngeal sparing therapies with radiotherapy and/or combined with chemotherapy
Neck therapy for regional disease – surgery and/or RT/chemotherapy