Laryngomalacia, tracheomalacia and vocal-cord dysfunction: SAQ

This infant has the classic picture of mild laryngomalacia: position-dependent inspiratory stridor beginning in the first fortnight, worse with feeding, crying and supine posture, in a thriving baby with a normal cry and no red flags. The task is to recognise the benign natural history, localise the airway lesion by the phase of the noise, and give a clear safety-net without over-investigating. [2]

Question 1 (10 marks)

How do you localise a noisy airway in an infant, what is the most likely diagnosis here, and how would you confirm it? (5 marks for the localisation principle; 3 marks for the diagnosis and its supporting features; 2 marks for confirmation.) [3]

A noisy airway is localised by the phase of the respiratory cycle in which the noise occurs. Inspiratory stridor points to the extrathoracic airway at the larynx or above, because the negative intraluminal pressure of inspiration draws the walls inward; expiratory noise points to the intrathoracic trachea and bronchi, which are compressed as pleural pressure rises in expiration; and a biphasic noise points to a fixed lesion at or near the glottis or subglottis. This single rule organises the whole assessment. [3]

The most likely diagnosis is laryngomalacia, the commonest cause of stridor in infancy. The supporting features are the onset at around two weeks rather than at birth, the high-pitched inspiratory quality, and the characteristic worsening with feeding, crying and the supine position with improvement when prone. The normal cry, the absence of biphasic stridor, and the good weight gain all point toward benign disease rather than a fixed or additional lesion. [2]

Confirmation is by awake flexible nasolaryngoscopy in the clinic, which shows the dynamic supraglottic collapse — an omega-shaped epiglottis, short aryepiglottic folds and redundant arytenoid mucosa prolapsing into the airway on inspiration. It must be performed with the infant awake and spontaneously breathing, because the collapse is dynamic and would be missed under deep anaesthesia. In a thriving infant with a typical history and no red flags, some clinicians observe and reserve laryngoscopy for atypical or severe features. [1]

Question 2 (10 marks)

Outline the severity grading and natural history of laryngomalacia, list the red flags that would change your management, and state the indications for surgery. (4 marks for severity and natural history; 4 marks for red flags; 2 marks for surgical indications.) [1]

Laryngomalacia is graded by its functional impact. Mild disease is stridor alone; moderate disease adds feeding difficulty, occasional choking and mild recession; and severe disease brings apnoea, cyanosis, faltering growth, cor pulmonale or dying spells. The natural history in the large majority is benign: symptoms peak over the first months of life and then resolve spontaneously, usually by twelve to twenty-four months of age, so most infants need only reassurance, positioning advice and growth monitoring. Where reflux contributes to symptoms, anti-reflux measures and a trial of acid suppression are reasonable, though routine acid suppression is not given to every infant. [2]

The red flags that change management and prompt urgent airway referral are stridor present from birth, a biphasic noise, a weak or abnormal cry, apnoea or cyanosis, and faltering growth or feeding failure. These features point away from simple laryngomalacia toward a fixed or additional lesion such as a vocal-cord palsy, subglottic stenosis or subglottic haemangioma, and it is important to remember that a significant minority of infants with laryngomalacia have a synchronous second airway lesion. Any of these features lowers the threshold for full airway endoscopy under anaesthesia. [1]

The indication for surgery is severe disease: an infant with apnoea, cyanosis, faltering growth, cor pulmonale or feeding failure. The operation is supraglottoplasty, in which the short aryepiglottic folds are divided and the redundant arytenoid mucosa is trimmed to relieve the inspiratory obstruction. It resolves or greatly improves symptoms in most children; a small group with treatment failure or significant comorbidity may need further surgery or, rarely, a tracheostomy. [1]