Isolated congenital laryngeal web (ORPHA:2374)
A rare laryngeal malformation characterized by a membrane-like structure of variable thickness that extends across the laryngeal lumen, between the vocal cords.
Epidemiology
The worldwide prevalence is unknown. Congenital laryngeal web represents fewer than 5% of congenital laryngeal anomalies.
Clinical description
Manifestations may appear at any age (mostly with hoarse or weak voice) but onset usually occurs during infancy (respiratory distress, stridor and an unusual cry). Clinical manifestations and their severity vary with the extent of obstruction and glottic involvement. Webs are categorized in the Cohen classification on the basis of glottic involvement. Type 1 are thin webs with <35% of glottic involvement. Type 2 are webs with 35-50% of glottic involvement. Type 3 are webs with 50-75% of glottic involvement and subglottic stenosis due to anterior cricoid cartilage extension; type 4 are webs with 75-90% of glottic involvement and subglottic stenosis due to anterior cricoid cartilage extension. Other larynx anomalies, such as laryngeal cleft and congenital subglottic stenosis, may be associated with this malformation.
Etiology
The malformation is a result of anomalous embryologic development of the larynx, stemming from incomplete resorption of the epithelial layer that normally obliterates the developing laryngeal opening at about the sixth week of gestation. This layer is usually completely eliminated by the tenth week. Since resorption proceeds from the dorsal to the ventral side, laryngeal webs are anteriorly located, leaving a posterior lumen. Although no gene was been specifically identified as the cause for this malformation, over half of the patients present with a syndromic form of the disease caused by a chromosome 22q11.2 deletion. Other genetic syndromes may also be associated with this malformation.
Diagnostic methods
Diagnosis of congenital laryngeal web is based on clinical signs (dysphonia, respiratory distress) and laryngeal endoscopy. A significant part of the patients presents with comorbidities such as chromosomal and cardiovascular anomalies. Patients should undergo genetic screening, which must include testing for a chromosome 22q11 deletion, and a thorough cardiovascular evaluation, which should include imaging of the aortic arch.
Differential diagnosis
Apart from syndromic forms linked to 22q11.2 deletion syndrome, the differential diagnosis includes laryngeal congenital complex stenosis, laryngeal papillomatosis, and subglottic cysts.
Genetic counseling
Genetic counseling with testing for 22q11 deletion is highly recommended. The mode of inheritance is autosomal dominant and families should be informed that there is a 50% risk of having an affected child at each pregnancy.
Management and treatment
The primary goals of treatment are to provide a patent airway and to achieve a good voice quality. However, vocal cords have a tendency for restenosis, fibrosis and granulation tissue formation after a surgical procedure and notably at their anterior part, where the web is usually located. The management and treatments range from surveillance (for small and thin web with no effect on ventilation and no or light dysphonia) to endoscopic section with cold instruments or laser. A laser should be used carefully because of the alleged extra scarring the burns induce, increasing the risk of restenosis. Good voice quality is mainly achieved in patients with thin, membranous, uncomplicated webs. Treatment for thick webs, with or without associated congenital subglottic stenosis, remains unsatisfactory. Thick webs can be assimilated to congenital laryngeal stenosis, and therefore treated by endoscopic section but above all laryngoplasty by external approach and stenting.
Prognosis
The laryngeal prognosis is usually good even if the dysphonia may not disappear totally over time.

                            Last update: 
                            July 2023


                            - Expert reviewer(s): 
                            Pr Nicolas LEBOULANGER | ERN CRANIO* - Dr Roman LUSCAN | ERN CRANIO* - Dr Briac THIERRY | ERN CRANIO*


                                * European Reference Network