Characterization of Noisy Breathing

Noisy breathing in a neonate (birth to 1 month age), infant (1 to 12 months), and child (1 to 12 years) can be characterized in several ways and is a reflection of turbulent airflow at some level of the airway. The word stertor is derived from the Latin word stertere , which means “to snore.” The term stertor can be used to describe noisy breathing from the vibration of tissues above the level of the larynx. In contrast, stridor is the hallmark of any laryngeal obstruction and can be described as a high pitched, musical, or harsh sound often mistaken for “wheezing.” Stridor and stertor can be heard on exam without auscultation and can be correlated with phase of breathing, wakefulness, sleep, and feeding. On auscultation, noisy breathing can be an indication of tracheal sources of turbulent airflow.

Much can be learned about the nature of the airway obstruction by closely observing the infant and listening to the noise produced as air passes through the obstruction. Stertor can result from obstruction at the level of the nose, nasopharynx, oropharynx, hypopharynx, and/or supraglottis. Stridor that results from glottic obstruction is typically present on inspiration, whereas biphasic stridor originates from obstruction at or below the level of the glottis, in the subglottis and upper trachea; expiratory stridor is the result of lesions in the distal trachea or mainstem bronchi. The differential diagnosis of airway pathology in a child can be divided by characteristics that reflect the level of the airway affected, either above or below the larynx ( Tables 23-1 through 23-3 ).

Noisy breathing is the hallmark symptom that leads to an airway evaluation. Severity of the airway process and need for intervention can be determined by level of distress, cyanosis, hypercapnea, poor weight gain or failure to thrive, difficulty feeding, difficulty sleeping, and obstructive sleep apnea.

History

Obtaining a history that elicits whether the noisy breathing is positional or related to states of wakefulness, sleep, or feeding is helpful in determining a differential diagnosis. Important features also include age of onset, exacerbating and ameliorating features, presence of progression, and occurrence of cyanosis. History of illness or recurrent pneumonia and comorbidities such as Down syndrome are useful in identifying associated factors. A history of intubation, prematurity status, and history of cardiac surgery increase suspicion for glottic or subglottic processes. History of a choking episode raises the suspicion of foreign body aspiration.

Physical Exam

The exam of the child begins with an overall assessment of size relative to age, level of distress, retractions, posturing, irritability, level of fatigue, and skin color. Evidence of syndromic features should be noted. Severe obstruction may be inferred by the type and anatomic level of retractions, including nasal flaring, suprasternal retractions, subcostal retractions, and intercostal retractions; the latter reflects recruitment of additional chest muscles for respiration. Altered voice quality may lead to a higher suspicion for a laryngeal process, especially if the child is aphonic, has a muffled voice, or does not generate a cough. Phase of stridor with inspiration or expiration is timed with chest motion. A complete head and neck exam and auscultation of the chest should be performed. Nasal and nasopharyngeal patency can be inferred when fog is seen under each nostril with a mirror.

Endoscopy

Dynamic evaluation of the larynx by flexible laryngoscopy is best performed in the patient who is awake. Although at least a 2.5-mm diameter fiberoptic laryngoscope is recommended for optimal viewing, fiberoptic laryngoscopes with diameters as small as 1.9 mm allow the neonatal larynx to be viewed with a minimum of trauma to the young patient. Viewing the fiberoptic laryngoscopy from a monitor allows for a magnified view of the pediatric larynx. Technology that provides the ability to record and review the exam with slow motion views, frame by frame views, and stroboscopy may greatly aid in the evaluation of the dynamic pediatric larynx.

Direct laryngoscopy of the neonatal larynx with a telescope or microscope provides the best optics ( Fig. 23-1 ) and requires general anesthesia, often performed by a pediatric anesthetic team familiar with techniques to provide spontaneous respirations that allow for a full evaluation of the airway before intubation or airway manipulation is performed. Techniques of total intravenous anesthesia, using propofol-remifentanyl intravenously, and of sevoflurane volatile induction/maintenance anesthesia have been well described to allow for spontaneous respirations while permitting airway manipulation. The endoscopist should fully evaluate the larynx and note findings in the valleculae, piriform fossae, postcricoid region, arytenoids, interarytenoid area, aryepiglottic folds, epiglottis, false vocal cords, ventricles, true vocal cords, and the subglottis. A bronchoscopy can be completed with a telescope or Hopkins rod, and the trachea and mainstem bronchi can also be evaluated.

Normal infant larynx. Anatomic areas to be examined include epiglottis, vallecula, piriform sinuses, arytenoid cartilages, interarytenoid area, aryepiglottic folds, false vocal cords, ventricles, true vocal cords, anterior commissure, and subglottis.

(From Benjamin B. The pediatric airway, In Slide Lecture Series, American Academy of Otolaryngology–Head and Neck Surgery, 1992.)

Vocal Fold Paralysis

Vocal fold paralysis (VFP) is another common cause of neonatal stridor. The stridor is inspiratory or biphasic with a high-pitched musical quality. VFP in a newborn may result from birth trauma, thoracic diseases or procedures, central or peripheral neurologic diseases, or from idiopathic causes. Birth trauma or forceps delivery results in a traction-type injury to the neck, associated with hematoma, soft tissue swelling, and/or compression injury to the vagus nerve as it descends in the neck. Traumatic intubation or aggressive suctioning may also result in direct laryngeal trauma and VFP.

Iatrogenic left VFP is a known complication of thoracic surgery, particularly patent ductus arteriosus ligation or repair of an interrupted aortic arch, which may be associated with difficulty weaning the infant off ventilator support. The left recurrent laryngeal nerve is susceptible to injury at the point that it passes around the ductus arteriosus, unless a right aortic arch is present. The incidence of recurrent laryngeal nerve injury is estimated at 1% to 7.4% of patent ductus arteriosus ligation cases. Tracheoesophageal fistula repair, pediatric thyroidectomy, and transcervical resection of branchial anomalies have also been associated with VFP.

The diagnosis is best made by FFL in the awake patient so that the effect of anesthesia on vocal fold function is minimized. The combination of a small dynamic glottis and collapsing supraglottic tissues in infants can make the diagnosis of VFP difficult. VFP may be unilateral or bilateral; bilateral VFP of neurogenic origin cannot be differentiated from bilateral vocal fold fixation by FFL alone, direct laryngoscopy with palpation is necessary. Pediatric laryngeal electromyography has been found to be useful in the diagnosis and management of VFP ; when performed under a light plane of anesthesia, it is helpful to differentiate fixation from paralysis and assist with prognosis.

The presenting symptoms for infants with a unilateral VFP include a weak cry or stridor, aspiration, dysphagia, or feeding difficulties. The voice of most infants with a unilateral VFP is quiet but audible and gains strength with time. The patient with unilateral VFP is often able to compensate for purposes of feeding without medical intervention. Sometimes an infant will require nasogastric feeds on a short-term basis or a gastrostomy tube. An occupational or speech pathology feeding consult is helpful with these infants to rule out aspiration (as seen on modified barium swallow) and to counsel the parents on how to feed the patient. Most often, these infants should start with a slow-flow nipple and work up to a regular nipple.

Children with bilateral VFP often have severe airway obstruction, which requires a tracheotomy in up to 73% of children. Bilateral VFP is often the presenting symptom leading to diagnosis of many neuromuscular diseases, including fascioscapulohumeral myopathy, spinal muscular atrophy, and congenital myasthenia gravis. Meningomyelocele and Arnold-Chiari malformation may lead to herniating contents in the posterior fossa and/or hydrocephalus, which causes pressure injury on the vagus nerves as they exit the skull base. Neonatal subdural hemorrhage may also present with bilateral VFP.

Workup of patients with idiopathic bilateral VFP should include a magnetic resonance imaging (MRI) scan of the brain to rule out an Arnold-Chiari malformation or other intracranial cause of brainstem compression ; early decompression is recommended to obtain a better outcome. Genetics consultation to evaluate for chromosomal abnormalities is recommended for patients with idiopathic congenital bilateral VFP.

When unilateral VFP results in severe aspiration and dysphonia, injection of the vocal fold may be helpful. The most commonly injected materials include cadaveric dermis (Cymetra), calcium hydroxyapatite (Radiesse or Radiesse Voice Gel), hydrated porcine gelatin powder (Surgifoam), absorbable gelatin sponge (Gelfoam), or autologous fat. Alternatively, in the older child, a medialization laryngoplasty (thyroplasty) can be performed, taking into consideration that the vocal fold lies in an anatomically lower position in children compared with adults. However, not all children may be able to cooperate intraoperatively with vocal tuning. Vocal fold reinnervation has been described to restore vocal fold tone, thus providing neuromuscular medialization without the use of an implant. Ansa cervicalis to recurrent laryngeal nerve reinnervation has been described, which required 3 to 6 months for results, with improvement in vocal functioning reported.

Approximately 70% of noniatrogenic unilateral vocal fold paralyses will resolve spontaneously, most within the first 6 months of life. In one study of children evaluated by a pediatric otolaryngologist, 35% of those with unilateral vocal fold paralysis after cardiac surgery recovered vocal fold function; at least half of the patients had swallowing dysfunction, usually aspiration or laryngeal penetration evident on modified barium swallow. Although many of the patients with a unilateral vocal fold paralysis were able to feed orally, many initially required a gastrostomy tube.

The vocal folds spontaneously become mobile in up to 65% of patients with bilateral VFP. Prognosis is better if there are no associated anomalies. Most recovery of vocal fold function occurs within 24 to 36 months, although it has been reported in patients up to 11 years of age. If recovery occurs after 2 to 3 years, it is often incomplete because of laryngeal muscle atrophy, cricoarytenoid fixation, and/or synkinesis. The timing of possible surgical intervention is debated. Some authors recommend intervention at a young age, whereas others suggest waiting until adolescence when the patient is able to decide.

Many surgical options are available to improve the airway of a patient with bilateral vocal cord paralysis, which implies that none is uniformly successful, particularly in the young patient. Endoscopically, a lateral cordotomy can be performed to increase the glottic area. Arytenoidectomy may be performed via an endoscopic or external cervical approach or the Woodman approach. Alternatively, an arytenoidopexy can be performed using a laterocervical approach. Triglia and colleagues performed an arytenoidopexy on 34 children with bilateral vocal cord paralysis (mean age, 20 months). Of the 15 children who had a tracheotomy or endotracheal tube before the procedure, 14 were successfully decannulated postoperatively. Another option is to expand the cricoid cartilage by placing a costal cartilage graft posteriorly, thereby separating the arytenoids and increasing the area between the vocal folds. This procedure can be performed with a laryngofissure or endoscopic approach. Finally, lateralization of the paralyzed cord has been described as a potentially reversible approach to vocal cord paralysis.

Hartnick and colleagues described 52 children who underwent surgery for bilateral VFP. The procedures most successful in realizing tracheotomy decannulation were those that included vocal cord lateralization procedures combined with a partial arytenoidectomy (71% decannulation rate). These procedures were more successful than CO ₂ laser cordotomy or arytenoidectomy procedures (29% decannulation), isolated arytenoidopexy procedures (25% decannulation), or posterior costal cartilage graft procedures (60% decannulation). No prospective randomized studies have been performed to evaluate the outcomes of these different surgical options, although meta-analysis has suggested that external arytenoidopexy and external arytenoidectomy are more effective than carbon-dioxide ablation procedures.

Paradoxic Vocal Fold Motion

Paradoxic vocal fold motion may result in stridor in the neonate, infant, and child. The classic presentation is a patient with episodic stridor that is loud and high pitched, interspersed with periods of normal breathing. The history and presentation in a neonate vary greatly from that of an older child, although the exam findings are the same. The evaluation for stridor begins with an awake fiberoptic laryngoscopy. Vocal fold motion must be observed and timed with inspiration and expiration; the endoscopist will note that with inspiration, the vocal folds are adducted, especially the anterior vocal folds. Video recording of the endoscopy with slow motion and frame-by-frame views may aid in the diagnosis. Whereas a neonate may present with stridor at birth, the stridor may be more pronounced with crying episodes. This form of stridor in a neonate tends to be short lived and often resolves on its own within a few months of life, or it may be associated with significant gastroesophageal reflux. A child or adolescent may have stridor from paradoxic motion associated with stress, anxiety, or exercise, which is often confused with asthma. There have been reports of paradoxic vocal fold motion causing obstructive sleep apnea. The pathophysiology of paradoxic vocal fold dysfunction is unknown, but laryngeal hyperresponsiveness is suspected to play a role. Treating sources of laryngeal sensitivity such as postnasal drip, gastroesophageal reflux, laryngopharyngeal reflux, and/or psychological conditions may be of benefit. Speech therapy and breathing exercises have also been reported to be helpful.