The most common causes of laryngeal stridor are laryngomalacia (60%), vocal cord paralysis (VCP) (10 %) and subglottic laryngeal stenosis. Majority of cases of VCP are idiopathic, less frequently it is the effect of abnormalities in central nervous system (Arnold - Chiari syndrome, hydrocephalus, neonatal hypoxia). Differential diagnosis should also include anomalies of aortic arch and its branches (vascular rings). The authors present two cases of neonatal congenital laryngeal stridor. In the first case the girl presented with VCP of unknown etiology. The perinatal period was normal, ultrasound of central nervous system and neurologic examination revealed no abnormalities. Due to sustained VCP in control laryngeal ultrasound examinations, tracheostomy was performed in the third month of life. In the second case, stridor was caused by laryngomalacia and subglottic laryngeal stenosis of first grade according to Meyer-Cotton scale (larynx lumen diameter <4 mm). The diagnosis was established by laryngotracheobronchoscopy. In both children angiotomography was performed and vascular ring was diagnosed (aberrant right subclavian artery). Vascular anomaly was suspected in barium X-ray. In both cases echocardiographic examination did not visualize the fourth vessel of the aortic arch. Chest X- rays were normal. Both children had no symptoms caused by vascular ring.
Conclusion: Diagnosis of congenital laryngeal stridor is an indication for complete evaluation to establish the cause of the airway obstruction. The differential diagnosis should include laryngomalacia, vocal cord paralysis, subglottic laryngeal stenosis, congenital anomalies of large vessels and abnormalities of the central nervous system.