Stridor in children: Is airway always the cause?

Stridor in children is usually, but not always caused by airway pathology. The anesthesiologists should have a sound knowledge of the neurological associations of stridor and its management. In such cases, prompt treatment of the neurological pathology usually resolves the stridor and may prevent unnecessary airway evaluation and intervention in the child.

Introduction

Stridor in children is usually due to airway pathology but neurological conditions causing stridor are not infrequent. In cases with an underlying neurological pathology causing stridor, the treatment of the underlying cause usually relieves the stridor. We report the association of stridor in a child presenting with hydrocephalus and raised intracranial pressure following the repair of a lumbosacral myelomeningocele; where the stridor resolved after the placement of a ventriculo-peritoneal (V-P) shunt. To the best of our knowledge, only one similar case has been reported earlier.

Case Report

An 8-month-old female baby born at term by normal vaginal delivery, from a second-degree consanguinous marriage; presented with noisy breathing and progressive increase in the size of the head for 4 weeks. There was no history of apneic or cyanotic episodes. The mother reported mild pharyngonasal reflux during feeding but no episodes of vomiting. The child underwent lumbosacral myelomeningocele repair 2 months ago. On examination, she was awake, irritable and had noisy breathing that was aggravated on crying. There were no other signs or symptoms of respiratory distress. Her heart rate was 123/min, blood pressure was 80/50 mm of Hg, respiratory rate was 38/min and oxygen saturation was 99% on room air. Glasgow Coma Scale was 15/15, head circumference was 48 cm and the anterior fontanelle was bulging and tense. Neurological examination revealed bilateral lateral rectus paresis but no up gaze paresis. Both upper limbs were spastic and the lower limbs were flaccid with grade 0 power. Contrast enhanced computed tomography (CECT) brain showed dilatation of all the ventricles s/o obstructive hydrocephalus [Figure 1]. She was posted for an emergency V-P shunt insertion.

Figure 1

Contrast enhanced computed tomography brain showing dilatation of all the ventricles s/o obstructive hydrocephalus

Informed high-risk consent was obtained from the parents for the procedure. Standard American Society of Anesthesiologists monitors, including electrocardiogram, noninvasive blood pressure, SpO2, EtCO2 and temperature monitoring were used. Inhalational induction of anesthesia was accomplished using 2–6% sevoflurane in oxygen. Intravenous propofol and fentanyl were administered after securing peripheral venous access. Tracheal intubation was facilitated by atracurium with a size 3.5 uncuffed endotracheal tube. The left side V-P shunt (medium pressure Chabbra system) was placed, and tracheal extubation was uneventful. The child was transferred to the neurosurgical Intensive Care Unit for monitoring.

Postoperatively the child's stridor decreased, head circumference was 47 cm, anterior fontanelle became lax, and she became active, playful and started feeding normally.

Discussion

The association of myelomeningocele with hydrocephalous and stridor has been reported earlier.[12345] In the report by Kirsch et al., the child underwent myelomeningocele repair and a ventriculoatrial shunt was placed at the age of 23 days but presented with cyanosis and stridor at the age of 16 months requiring tracheostomy.[1] Ravilochan et al. described a child presenting with hydrocephalous and stridor, 5 months after she underwent lumbar myelomeningocele repair. The child's family refused a V-P shunt with a fatal outcome.[2] Solan and Glaisyer described a neonate with stridor after the development of hydrocephalus secondary to surgical repair of the lumbosacral myelomeningocele. In this report, the stridor resolved completely after an emergency ventricular tap was performed, and the VP shunt procedure was performed only later.[3] Similar to our case, Adeloye et al. described a child who presented initially with lumbar myelomeningocele and later developed hydrocephalus and severe laryngeal stridor, that resolved dramatically after the placement of a V-P shunt.[4]

Stridor is defined as the sound caused by abnormal air passage into the lungs and may be caused by extra thoracic (nose, pharynx, larynx, trachea) or intra-thoracic airway (tracheobronchial tree) obstruction. Stridor in neonates can be congenital or acquired. Laryngomalacia is the most common cause of congenital stridor.[6] Other causes include secondary airway lesions, vocal cord paralysis (VCP), subglottic stenosis, tracheal anomaly, laryngeal cleft, vascular and lymphatic malformation, laryngeal papillomas, craniofacial abnormalities, and even head and neck tumors.[7] The stridor in our case was probably due to unilateral vocal cord palsy due to stretching of the vagus nerve as it resolved promptly after the V-P shunt was performed. The differential diagnoses in our case could be bilateral vocal cord palsy or other congenital or infective laryngeal pathology causing stridor.

Vocal cord paralysis may be idiopathic, iatrogenic, and secondary to neurological abnormality including Arnold Chiari malformation [ACM], cerebral palsy, hydrocephalus, myelomeningocele, spina bifida, or hypoxia or birth trauma.[6] Holinger et al. described 21 infants and children with bilateral abductor VCP and associated meningomyelocele, ACM, and hydrocephalus. They reported a temporal relationship between increased intracranial pressure (ICP) and VCP, apnea, aspiration, and dysphagia.[8] According to Chen and Inglis in infants with bilateral VCP, ACM with hydrocephalous and myelomeningocele is the commonest neurologic finding.[9]

Various causes have been proposed for the development of VCP in patients with raised ICP with neurological disorders including; the downward displacement of the brainstem secondary to increased ICP; stretching, compression or ischemia of the vagus nerves during their course from the nuclei ambiguii to the jugular foramen;[910] circulatory impairment of the brainstem and primary brainstem dysgenesis with hypoplasia of the cranial nerve nuclei.[11]

The treatment options include decompression of increased ICP by temporary measures such as cerebrospinal fluid tap followed by a definitive V-P shunt or decompression of the foramen magnum to reduce the pressure difference between intracranial and intra spinal compartments. Usually, the stridor will be relieved after the decompression procedure[3481213] but some authors have reported worsening of symptoms after the surgical procedure.[1014] Tracheal intubation and immediate ventricular puncture are the recommended emergency measures. Ideally the ventricular shunt should be performed within 48 h of onset of hindbrain dysfunction. Tracheostomy may be required if the stridor does not resolve by 48 h after the definitive surgical procedure. In the perioperative period, anesthesiologists should be aware of complications occurring during induction and maintenance of anesthesia. The avoidance of further increase in ICP at the time of induction and intubation cannot be over emphasized. Further increase in ICP may result in adverse cardiac events and cardiac arrest. Early visualization of the larynx is required in patients who become stridulous postoperatively, especially those who have undergone prior thoracic procedures or with neurologic disorders associated with intracranial hypertension.[13]

Conclusion

Stridor in children is not always due to airway pathology and clinicians should be aware of the neurological associations of this symptom. When associated with neurological conditions, relieving the neurological condition often decreases the stridor and hence may avoid unnecessary airway intervention and evaluation.