Congenital disorders of the larynx

The larynx develops from the fourth and fifth branchial arches. At the third week of gestation, the respiratory primordium is derived from the primitive foregut to later form the lung bud and later the bronchial bud which will eventually develop into the tracheobronchial tree.

At the fourth and fifth week of gestation the tracheo-oesophageal folds fuse to form the tracheo-oesophageal septum leading to the separation of the tracheal airway lumen from the esophageal digestive tract.

The pediatric Larynx

The newborn larynx is about one third the size of the adult counterpart.

The diameter of the subglottic and glottis are narrower which leads to an increase propensity for airway obstruction and compromise.

The subglottic region is about 4 to 5 mm in diameter. The epiglottis is also narrower in infants. The larynx lies at the level of the third/fourth cervical

vertebrae at birth. By fifteen years of age it has descend to the level of

the sixth vertebrae.

These dimensions leave little margin for obstruction in the infant, unlike the adult.

The narrowest portion of the airway in the older child and adult is the glottic aperture, while the narrowest part of the airway in the infant is the subglottis.

A diameter of 4.0 mm is considered the lower limit of normal in a full term infant and 3.5 mm in a premature infant.

Indeed, an infant with one millimeter of glottic edema will experience a 35% obstruction of the airway.

In the subglottis, one millimeter of circumferential edema leads to over 60% narrowing.

Clinical Manifestations of congenital anomalies Respiratory obstruction Stridor Weak cry Dyspnoea Tachypnea Aspiration Cyanosis Sudden death

LaryngomalaciaSubglottic stenosisSubglottic hemangiomaLaryngotracheal cleftsLaryngoceleLaryngeal web/ atresiaVocal cord palsy

Laryngomalacia The most common typeThe larynx is of an exaggerated infantile type.

The epiglottis is long, narrow and folded backwards(omega shaped). The laryngeal inlet is therefore deep and narrow.

Stridor is the main symptom and appears within the first 2 weeks of life, it is intermittent and inspiratory, diminished by rest and sleeping and on lying on prone position, and increase in severity on exertion and crying.

The condition will disappear between the 2nd and 5th years of life. Infrequently it is sever causing feeding difficulties, failure to thrive, apnea and cyanosis.

On examination the laryngeal inlet is deep and narrow and there is collapse of the supraglottic structures on inspiration

Treatment: reassurance is usually all that is necessary. Surgery is rarely needed.

Normal Larynx

Laryngomalacia

The supraglottic structures are pulled into the lumen around a vertical axis with inspiration

Collapse of arytenoid mucosa; shortened aryepiglottic folds; tubular epiglottis with posterior collapse

Subglottic stenosisDefined as a cricoid diameter of less than 3.5 mm

in full term infant.Clinical features: stridor either inspiratory or

biphasic which is partially relieved by rest and worsened by exertion but not affected by posture. Feeding difficulty and failure to thrive

Treatment: conservative in mild cases. Tracheostomy in sever cases, growth of the subglottis allow decannulation after some years or laryngotracheal reconstruction to expand the cricoid.

Subglottic hemangiomaClinically is indistinguishable from subglottic

stenosis and the treatment is the same. Laser is particularly effective.

Might be associated with external hemangiomas.

Laryngotracheal cleftsDue to incomplete development of the

tracheo-esophageal septum.Clinical features: stridor, aspiration and

recurrent pneumonia.Diagnosis: Ba swallow and endoscopic

examinationTreatment: clefts at or above the cords

treated conservatively. While clefts below the cords cause aspiration and require open surgical repair.

LaryngoceleOriginate from the laryngeal ventricleDilated sac filled with airEither internal or external. Small cyst

present as hoarseness or muffled cry. Larger ones cause inspiratory stridor.

Treatment: endoscopy is required to evacuate and uncap the cyst. Treatment may need to be required.

Laryngeal web/atresiaWeb formed due to arrest in development or

failure of recanalization of the larynx and consists of a fibrous stroma covered by epithelium. The most sever form of laryngeal web is total atresia which is incompatible with life.

Clinical features: hoarseness and inspiratory stridor.

Treatment: mild cases treated conservatively while sever cases require tracheostomy and surgical excision.

Laryngeal webs

Vocal cord palsyDue to birth trauma or idiopathicUnilateral or bilateral.Clinical features: inspiratory stridor and

hoarseness.Treatment: Mild cases treated conservativelySever cases require tracheostomy and

surgical intervention.

Stridor and StertorAuditory manifestations of disordered respiratory function

Stertor:

Low pitched snoring or snuffly sound caused by obstruction of the airway above the larynx; in the nose, nasopharynx and oropharynx.

Stridor:

Noisy breathing due to obstruction at the level of the larynx, trachea or bronchi.

Both due to turbulence of airflow within a partially obstructed respiratory tract.

While stertor is always inspiratory, stridor could be inspiratory, expiratory or both(biphasic)

Causes of stertor 1- congenital 2- traumatic 3- inflammatory 4- neoplastic 5- allergic rhinitis and nasal polyp 6- hypertrophied tonsils and adenoid

Causes of stridor: 1- congenital 2- traumatic 3- foreing body 4- inflammatory 5- neoplastic 6- allergy 7- pressure on the larynx, trachea or bronchi from without.

Management of stertor and stridor

1- History a- age of onset b- character c- onset d- associated features e- review of other systems f- smoking and alcohol dinking g- pastmedical and surgical history

2- Examination a- general exam. b- vital signs c- nasal exam. d- exam. Of the oral cavity and oropharynx e- exam. Of the larynx f-exam. Of related systems : lungs,heart and CNS.

3- Investigations: a. Pulmonary functon test and arterial blood gases b. Laboratory c. Radiological: 1- plain x-ray 2- CTS and MRI 3- Ba swallow, angiography and thyroid scan d- endoscopy : panendoscopy

4- Treatment: a- hospital admission b- careful follow up c- conservative measures d- tracheostomy or endotracheal intubation in sever cases e- traetment of underlying cause