Recurrent stridor in an infant

Abstract

Paediatric upper airway obstruction is an emergency that requires immediate intervention. Among the myriad factors that leads to upper airway obstruction in paediatric age group, bilateral vocal cord palsy is not commonly encountered in clinical practice. The underlying cause of bilateral vocal cord palsy requires thorough investigation prior to deciding on the appropriate intervention. Herein, we report a 4-month-old baby boy who presented with recurrent inspiratory stridor with bilateral vocal cord palsy secondary to Arnold Chiari II malformation. Immediate intervention to drain the hydrocephalous resulted in complete resolution of stridor without having to perform a tracheostomy. We highlight the importance of meticulous and thorough investigations especially in children, as emergent airway intervention such as tracheostomy may result in detrimental effect to speech, swallowing as well as quality of life.

Background

Presence of stridor in children connotes upper airway obstruction whereby emergent airway intervention is executed in a tout de suite manner. Amidst the various causes of stridor in children, the most common cause of congenital stridor is laryngomalacia while the most common cause of acute stridor is croup.¹ Nevertheless, it is noteworthy that not all causes of stridor in children are related to primary airway lesion. Vocal cord palsy (VCP) has been reported as the second most common cause of stridor in children accounting for 10% of congenital airway anomaly.² Lately, there has been increasing number of literature reporting on stridor with VCP secondary to various neurological disorders. However, the best choice of intervention remains a conundrum in whether a tracheostomy is warranted.

Case presentation

A 4-month-old male infant, with underlying Arnold Chiari malformation, presented with a 3-day history of noisy breathing, reduced feeding along with vomiting. Child is a second infant of dichorionic diamniotic twins’ pregnancy, born preterm at 36 weeks via lower segment caesarean section. Child has underlying lumbosacral myelomeningocele with Arnold Chiari II malformation diagnosed at birth and subsequently underwent lumbar myelomeningocele repair with ventriculoperitoneal (VP) shunt insertion at first month of life. Apart from that, there was no history of fever, seizure or any trauma. No history of recent travelling or sick family members.

On examination, child appears lethargic and tachypneic. Saturation maintained at 100% with 3 L of oxygen via a face mask. Inspiratory stridor is audible with prominent intercostal, subcostal and suprasternal recession. Bedside flexible nasopharyngolaryngoscopy revealed bilateral vocal cord paralysis in paramedian position with no other supraglottic anomaly or lesion noted.

Investigations

Urgent CT brain showed worsening dilatation of bilateral lateral and third ventricle (figure 1) with periventricular hypodensities and cerebral oedema. MRI performed shows herniation of brainstem and cerebellar vermis through foramen magnum (figure 2).

Figure 1.

Axial CT scan of brain shows dilated ventricles suggesting hydrocephalus.

Figure 2.

MRI view shows herniation of brainstem and cerebellar vermis through foramen magnum.

Provisional diagnosis of bilateral VCP (BVCP) secondary to obstructive hydrocephalus was made.

Treatment

Neurosurgical team performed emergency external ventricular drain (EVD) to relive the obstructive hydrocephalus.

Postoperatively, child was kept intubated for 3 days. Following extubation, no stridor was audible, and child was comfortable with no signs of respiratory distress. Subsequently, child had a revision VP shunt and was discharge back home after a month of hospital stay.

Outcome and follow-up

Repeated flexible scope in clinic review 3 weeks later showed mobile and symmetrical bilateral vocal cord with no phonatory gap. Child has been on regular follow-up with no complications.

Discussion

VCP is defined as absence of movement of vocal fold, which is more common in adult than in paediatric group.³ The occurrence has been traditionally attributed to either anatomical structure abnormality, or the dysfunction of nerve innervating the laryngeal muscle.⁴ In the same vein, most case series have categorised VCP into congenital or acquired and unilateral or bilateral. Although VCP secondary to idiopathic cause has been described as the most common cause of VCP, Daya et al reported iatrogenic as the most common cause of VCP among children in their case study.³ Other contributing factors of VCP include congenital, birth trauma as well as neurological pathology.¹

BVCP traditionally has been diagnosed by end of first month of life.⁴ Interestingly, neurological entity has been regarded as the second most common cause of paediatric VCP notably BVCP.² Spina bifida, intraventricular haemorrhage, cerebral palsy, myelomeningocele and Arnold Chiari malformation have been attributed as the aetiological factors of BVCP.²

Arnold Chiari malformation is the most frequent neurological entity causing BVCP among children.² Of the plausible theories that exists, BVCP secondary to Arnold Chiari malformation results from acute downward displacement of the malformed brainstem following increased intraventricular pressure leading to stretching, compression as well as ischaemic changes of vagus nerve and its course from nuclei ambiguous to jugular foramen.² Similarly, mechanical injury and vascular impairment to brain stem can also contribute to the dysfunction of vagus nerve¹

Children with Arnold Chiari malformation and VCP may not routinely present with classical symptoms of stridor or noisy breathing. Hence, clinicians should elicit salient history from parents such as apnea, week cry, dysphagia with recurrent aspiration pneumonia and choking.⁵

Infant presenting to emergency department with stridor should be managed cautiously. Although child presenting with stridor may be alarming, attending physicians should exercise caution as emergent decision for intervention may lead to a devastating outcome. Thorough history from parents’, in addition to meticulous examination is prudent.⁶ A flexible nasopharyngolaryngoscopy can be performed in the emergency department provided child is stable with no signs of respiratory distress which will confirm the presence of VCP. The presence of airway compromise which necessitates intubation should be performed in the operating theatre as airway assessment can be performed simultaneously. Laryngotracheobronchoscopy can be performed to assess the airway as well as mobility of the vocal cords.

Besides airway assessment, presence of BVCP warrants imaging as a part of investigation notably MRI. Presence of hydrocephalus with herniation of cerebellar vermis, medulla and fourth ventricle, requires immediate VP to prevent irreversible dysfunction of hindbrain which simultaneously reduces the compression to the vagus nerve.⁷ Ventricular shunting should ideally be performed within the first 48 hours from the onset of symptoms.^{2 7}

Other adjunct investigations of VCP in children include ultrasonography of neck and also CT of neck and thorax. The idea of laryngeal electromyography had been introduced to evaluate the severity and the prognosis of the VCP.³ However, its significance in the management of paediatric VCPy still remains a doubt.

Treating the primary neurological condition reverses the vocal cold cord palsy which prevents a more radical surgery such as tracheostomy in children. It is noteworthy that, VCP secondary to neurological disorder was found to have higher spontaneous recovery rate.⁸ In our case, emergent EVD performed, relieved compression to the vagus nerve thus resolving the BVCP. Until, there is yet a literature describes an exact duration of recovery of function of vocal cord after decompression.⁹ Although trial of conservative management is preferred for patient with VCP, tracheostomy still reported performed in most of the literature. Nisa et al summarised tracheostomy performed in 60% children who presented with BVCP with all kind of causes.^{3 9 10}

In our case, child was intubated for primary decompression and extubated on third day post decompression of hydrocephalus. Although we did not perform an immediate bedside flexible laryngoscope, the child did not develop stridor after the extubation.

Learning points.

• Arnold Chiari malformation presenting with stridor is a known entity

• Primary neurological pathology such as Arnold Chiari malformation ought to be ruled out in children presenting with bilateral vocal cord palsy (BVCP).

• BVCP secondary to neurological pathology such as hydrocephalous can improve once the hydrocephalous is drained.

• Thorough investigation along with meticulous history avoids unnecessary intervention such as tracheostomy, which may impair a child’s quality of life.

Ethics statements

Patient consent for publication

Obtained.