Stridor In Infants SAI YAN AU

Stridor Harsh, high pitched, musical sound produced by turbulent airflow through a partially obstructed airway. A sign May be inspiratory, expiratory or biphasic Inspiratory stridor – extrathoracic lesion (laryngeal, nasal, pharyngeal) Expiratory stridor – intrathoracic lesion (tracheal or bronchial) Biphasic stridor - subglottic or glottic anomaly

Stridor: Mechanism Venturi principle Gases produce equal pressure in all direction When gas move in a linear direction, it produces pressure in the forward vector and decreases the lateral pressure When air passes through a narrowed flexible airway in child, the lateral pressure that holds the airway can drop and causes airway to close – airflow obstruction – stridor

Stridor In Infants: Causes Laryngomalacia (congenital laryngeal stridor) Subglottic stenosis Laryngeal webs

Laryngomalacia (congenital laryngeal stridor) Most common cause of persistent stridor in infants (first 6 weeks of life) Congenital abnormality of the laryngeal cartilage Delay in maturation of cartilaginous support for the supraglottic structures No known sex and race predilection exists Causes – congenital

Laryngomalacia: pathophysiology May affect the epiglottis, arytenoid cartilages or both Epiglottis – elongated and the walls fold in on themselves ( OMEGA, Ω shaped) Arythenoid cartilage – enlarged Either cases, cartilage is floppy; prolapsed over the larynx during inspiration Increase risk of GOER Reflux laryngitis

Laryngomalacia History:- Hx of inspiratory noises; may sound like nasal congestion Stridor worse in the supine position, increased activity, URTI and during feeding but improved in the prone position with the head up Assoc. with pectus excavatum On Examination:- mild tachypnoea Normal or slight drop in O2 saturation Nasal airflow increase in supine position Noise is purely inspiratory

Laryngomalacia Investigations:- O2 saturation Fluoroscopy Laryngoscopy and bronchoscopy Treatment:- > 99%, no Rx is needed Simple tracheotomy or laryngoplasty

Subglottic Stenosis Narrowing of the subglottic which is housed in the cricoid cartilage no racial predilection exists equal sex distributions Causes: - congenital (in utero malformation of the cricoid cartilage) Acquired ( infections e.g. TB, diphtheria, typhoid and syphilis, mechanical trauma due to endotracheal intubation and GOER)

Subglottic Stenosis: Pathophysiology Congenital – incomplete canalization of the subglottis and cricoid rings, assoc. with trisomy 21 Acquired: - Trauma causes mucosal oedema and hyperemia; leads to pressure necrosis GOER – subglottis bathed in acid, irritates and inflames the area and prevent from healing

Subglottic Stenosis History: - Presence of biphasic and obstructive breathing Hoarseness or vocal weakness Clinical examination:- Complete head and neck examination Evaluate the child’s appearance, voice and neurological status Auscultate lung and neck Identify any associated features

Subglottic stenosis Investigations:- Direct laryngoscopy and bronchoscopy AP and lateral neck x ray Fluoroscopy Dual channel pH probe testing MRI and CT Scan Treatment:- Medical (steroids) Surgical (tracheostomy, cricoid split and laryngoplasty)

Laryngeal Web Uncommon (5% of congenital laryngeal abnormalities) Incomplete canalization of the larynx Sporadic and equal sex distribution Causes – congenital 4 types – based on the degree of occlusion Type I, II, III, IV

Laryngeal Web Pathophysiology: - Type I – 35% covering the anterior glottis Type II – 35 to 50% occlusion of the lumen with vocal cord visible Type III – 50 to 70% occlusion of the lumen with the vocal cord possibly visualized; most common Type IV – 75 to 90% occlusion with vocal cords not visualized Pathophysiology: - Developmental abnormality occurring between the 4th to 10th weeks of gestation Epithelial fusion between 2 sides of larynx fails to dissolve resulting in incomplete recanalization of the primitive larynx.

Laryngeal webs: Clinical Features Inspiratory and expiratory stridor +/- upper airway obstruction with respiratory distress Paroxysmal dyspnoea +/- cyanosis Aphonia, weak cry Poor feeding Assoc with respiratory and CVS problems (10% - 15%)

Laryngeal Webs Investigations:- Direct laryngoscopy or bronchoscopy Treatment:- Supportive (emergency) Surgery (thinner, thicker webs)

SUMMARY Laryngomalacia – delay in maturation of the cartilaginous support of supraglottic structures Subglottic stenosis – incomplete canalization of subglottis and cricoid cartilage Laryngeal web – fusion of the anterior portion of true vocal cords