An unusual case of stridor in the newborn

CASE

A late-preterm neonate (36 + 5 weeks) presented with stridor immediately after birth. Vaginal delivery was induced for intrauterine growth restriction and was uncomplicated. The initial physical examination was significant for a birth weight below the 10^th percentile, moderate to severe work of breathing (suprasternal and subcostal retractions), stridor, and self-resolving oxygen desaturations. The stridor was inspiratory and worsened with supine position and crying.

Endoscopic nasolaryngoscopy demonstrated an omega-shaped epiglottis and collapse of the supraglottic tissues on inspiration. The right arytenoid cartilage was antero-medially displaced. Visualization of the vocal folds was inadequate for assessment of movement. The findings were consistent with a presumptive diagnosis of severe laryngomalacia.

Over several days, the patient was noted to have a right Horner syndrome (Figure 1), prompting cross-sectional imaging of the head, neck, and upper chest. This ultimately led to the diagnosis—an unusual cause of stridor in the newborn.

Figure 1.

Patient’s Horner syndrome.

DISCUSSION

Stridor is a common physical finding in newborns. It is caused by turbulent airflow through a narrowed airway. Stridor can be inspiratory when the obstruction is located above the true vocal folds (supraglottic), biphasic when it is at the level of the vocal folds (glottic) or the subglottis, and expiratory if the narrowing is intrathoracic.

The differential diagnosis of newborn stridor includes laryngomalacia, unilateral and bilateral vocal fold paralysis, laryngeal web, glottic stenosis, subglottic stenosis, and lesions that obstruct the airway. The most common cause of stridor in the newborn is laryngomalacia, affecting 45%–75% of infants with congenital stridor (2). The etiology of laryngomalacia is unknown but considered to be due to a combination of anatomic (cartilaginous) and neurologic immaturity (2).

The typical presentation of laryngomalacia includes inspiratory stridor that increases with feeding, agitation, supine positioning, and should decrease in the prone position (4). Associated symptoms related to feeding include emesis, cough, and choking. In severe laryngomalacia (which occurs in up to 10% of cases), infants may have recurrent cyanosis, apneic pauses, and failure to thrive (2). The clinical presentation and findings on nasolaryngoscopy in this case were consistent with severe laryngomalacia (Figure 2).

Figure 2.

Patient’s larynx as viewed by direct laryngoscopy demonstrating typical features of laryngomalacia: omega-shaped epiglottis and shortened aryepiglottic folds.

While infants with mild to moderate inspiratory stridor and no feeding difficulties can be managed by observation, the severity of the clinical symptoms in this case necessitated hospitalization, feeding by nasogastric tube (NG), and close monitoring by the otolaryngology service during the admission.

The diagnosis was re-evaluated due to a finding of right eye ptosis, which prompted concern for Horner syndrome. An ophthalmologic exam confirmed the presence of ptosis, miosis, and anisocoria. A cocaine test, the gold standard for differentiating true Horner syndrome from physiologic aniscoria, was performed. Cocaine acts by inhibiting the reuptake of norepinephrine at sympathetic nerve synapses and causes pupillary dilation in patients with intact sympathetic innervation (1). Our patient did not have a pupillary dilation response, confirming Horner syndrome. Cross-sectional imaging of the head, neck, and upper mediastinum demonstrated a right-sided mass that encased the right common carotid artery and invaded the floor of the neck, causing left-sided displacement of the trachea and rotation of the thyroid, larynx, and esophagus (Figure 3). Ultrasound-guided core needle biopsies revealed a diagnosis of an infantile myofibroma, a rare benign soft tissue tumor.

Figure 3.

CT image (coronal view) of right-sided neck mass with deviation of the laryngotracheal complex to the left.

The stridor was considered to be caused by both severe laryngomalacia and the laryngotracheal deviation caused by the tumour. This case emphasizes the importance of recognizing the possibility that more than one diagnosis may be responsible for a constellation of airway symptoms. Moreover, it is advisable to consider a broad differential as new clinical information is identified. This case also highlights the importance of examining the eyes as part of a thorough head and neck exam, so as not to miss Horner syndrome—which may warn of an underlying malignant pathology (1). The classic triad of physical findings includes ptosis, miosis, and anisocoria, but not all findings are required to establish the diagnosis. The iris may also be hypopigmented on the involved side, as sympathetic innervation is necessary for pigmentation of the iris (1). Pediatric Horner syndrome most frequently results from an interruption to the preganglionic neurons of the sympathetic chain. It may be caused by neoplasms (neuroblastoma being the most common cause), as well as non-congenital causes such as neck trauma, brachial plexus injury, spontaneous pneumothorax, lymphadenitis, and cervical vertebral anomalies (3).

Thus, patients presenting with Horner syndrome without a clear history of birth trauma should be investigated for tumors with cross-sectional imaging of the neck and chest and urine catecholamine testing to biochemically detect neuroblastomas (3).

Our patient, unfortunately, had an unresectable lesion and required a tracheostomy to establish the airway and a gastrostomy tube for feeding. The patient responded remarkably to low-dose chemotherapy and repeat cross-sectional imaging demonstrated a significant decrease in the size of the lesion.

Clinical pearls

1. Although laryngomalacia is the most common cause of stridor in infants, a careful history and physical examination, endoscopy, and diagnostic imaging may be required to explore a wider differential diagnosis. Important red flags include weight loss, lethargy, fatigue, nystagmus, cranial neuropathies, and palpable cervical masses.

2. A thorough head and neck exam in a neonate with stridor should include examination of the eyelids and pupils.

3. Acquired Horner syndrome without a history of birth trauma should raise concern for a tumor (such as neuroblastoma) and should be investigated with imaging of the neck and chest.

FUNDING

There are no funders to report.

INFORMED CONSENT

Informed consent obtained to use the figures.

POTENTIAL CONFLICTS OF INTEREST

J.S. reports payments made to institution from the Ontario Crown Attorney for expert testimony. There are no other disclosures. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.