45.1 Introduction

Laryngomalacia is the most common cause of neonatal stridor, comprising up to 75% of all causes of congenital stridor. ^{1 – 4} Inspiratory collapse of supraglottic structures causes narrowing of the airway lumen resulting in inspiratory stridor. Due to its typically benign natural history of gradual improvement and eventual resolution by age 2 years old, laryngomalacia is most often managed conservatively. In approximately 10% to 15% of cases surgery is indicated because of dyspnea, failure to thrive (FTT), feeding difficulties, and other significant morbidity. ^{5 – 9}

45.2 Pathophysiology

The pathophysiology of laryngomalacia has not been completely elucidated. Hypotheses proposed to explain the seemingly weak supraglottic structures address issues of deficient cartilage maturation, weak muscle tone, and effects of laryngopharyngeal reflux (LPR). Although these processes may play a role, the more accepted current understanding suggests that altered laryngeal tone and sensorimotor integrative functions are the underlying cause. Laryngomalacia patients were found in clinical testing to have increased laryngopharyngeal sensory thresholds and submucosal nerve hypertrophy on histology, strengthening the neurological explanation. ^{10 , 11} These changes are thought to cause altered vagally mediated resting laryngeal tone. LPR is thought to play a role in this process. ^{12 – 15}

45.3 Presentation

Although stridor caused by laryngomalacia may be present at birth, the typical clinical course begins with normal breathing at birth and inspiratory stridor appearing by age 2 to 3 weeks. In some cases stridor may appear as late as several months of age. The severity of the stridor and airway obstruction may then increase gradually, plateauing by age 4 to 6 months. Most cases thereafter gradually improve until complete resolution by age 2 years. The stridor is described as an inspiratory high-pitched fluttering sound usually worse in the supine position with improvement when placed face down (this maneuver is used clinically to help characterize the stridor).

There are also other subtypes of laryngomalacia presenting differently such as late-onset laryngomalacia, ^{16 – 18} exercise-induced laryngomalacia, ^{19 , 20} and laryngomalacia presenting as obstructive sleep apnea. ^{21 – 24} These cases are managed differently but when surgery is indicated the same surgical principles as in infant laryngomalacia are applied. ^{17 , 25 – 27}

45.4 Symptoms

Activities increasing respiratory demands such as crying, feeding, agitation, and physical activity worsen the stridor. Airway obstruction with overt dyspnea is the hallmark of severe laryngomalacia and a clear indication for surgery. The work of breathing in moderate-to-severe cases often causes FTT, making severity more apparent. In the more severe cases apneic events and cyanosis may be present. Even in milder cases, patients may suffer from an array of feeding difficulties which may include dysphagia, choking episodes, and regurgitation that may also lead to FTT.

Comorbid conditions often associated with laryngomalacia include gastroesophageal reflux disease (GERD)/LPR, obstructive sleep apnea, neurologic or neuromuscular disease. ^{28 – 30}

These comorbidities may directly affect the management of laryngomalacia.

Pectus excavatum, cor-pulmonale, and pulmonary hypertension may develop in severe longstanding cases, secondary to chronic obstruction and must be evaluated preoperatively in order to avoid operative and postoperative complications.

Incidence of synchronous airway lesions (SALs) ranges from 12% to 50% and therefore thorough examination of the entire airway is mandatory. ^{31 – 34}

Many classifications and categorizations have been proposed for laryngomalacia. ^{35 – 38} The purpose of classification is to create a common language to describe and assess severity, assist with the management decision-making process, and in cases operated on to help apply appropriate pathology-specific tailored surgery. The classifications refer to both static and dynamic findings on endoscopy. Both of these elements are necessary towards understanding each child’s specific pathology and thus enabling correct surgical treatment. We find most useful the classification of Monnier who divides laryngomalacia into three types which associate with three different supraglottoplasty elements.

Type I: Inward collapse of aryepiglottic folds on inspiration.

Type II: Curled tubular epiglottis with shortened aryepiglottic folds, which collapses circumferentially on inspiration.

Type III: Overhanging epiglottis that collapses posteriorly, obstructing the laryngeal inlet on inspiration.

Diagnosis is usually confirmed by awake, office flexible laryngoscopy. Although this usually provides an accurate assessment, “sleep endoscopy” consisting of flexible fiberoptic laryngoscopy under general anesthesia with spontaneous breathing may be superior in providing the most accurate view of the true dynamic pathology. ^{39 , 40}

Less common laryngomalacia may appear at later age, present as cause or partial cause of OSA, and may be better recognized using sleep endoscopy. ^{16 , 17 , 21 , 22}

45.5 Indications for Surgery

Clinical assessment of laryngomalacia severity is best when viewed as a spectrum. The severity of laryngomalacia must be assessed firstly and most importantly based on its clinical effect on breathing, feeding, development, and growth and any other systemic parameter attributable to laryngomalacia. Flexible endoscopy is not only crucial for confirming diagnosis but also is an important adjunct to grade severity. One must correlate the clinical with endoscopic severity and when a discrepancy is seen, seek other pathology.

Indications for supraglottoplasty are severe stridor with respiratory compromise, feeding difficulties, FTT (when other causes are ruled out), and obstructive sleep apnea. Severe respiratory distress with suprasternal retractions, hypoxemia, or hypercapnia requires urgent surgery. The management of the laryngomalacia patient should be done by an aerodigestive team which may include a pediatrician, pediatric pulmonologist, pediatric gastroenterologist, pediatric intensivist, pediatric dietician/nutritionist, speech pathologist, social worker in addition to other professionals depending on comorbidities. Decision-making should be performed jointly after assessment and discussion with the team. Parents must be involved in the process and counseled. They must be provided with all pertinent information regarding their child’s health status, treatment options, complications, and realistic expectations. When the decision to perform surgery has been made, they must sign on informed consent.

45.6 Preoperative Evaluation and Anesthesia

When the decision to perform surgery has been made, the patient undergoes a thorough anesthesiologist evaluation. As with all pediatric airway procedure, precise, fine-tuned teamwork with all professionals in the operating suite is of utmost importance and a prerequisite for proceeding with the surgery. Pediatric airway surgery proposes a unique challenge to the anesthesiologist who must at times have the patient without a definitive airway, must “share” the airway with the otolaryngology surgeon, and good surgeon-anesthesiologist team-work cannot be over stressed.

The preferred surgical procedure is endoscopic supraglottoplasty, which is the focus of this chapter. When contraindicated the other surgical option is tracheotomy, which is described elsewhere.

45.7 Supraglottoplasty

Endoscopic supraglottoplasty is performed via suspension laryngoscopy under general anesthesia using spontaneous breathing. The anesthesiologist may use any of a large variety of methods to ventilate as needed, including bag ambo, intermittent LMA (laryngeal mask), intermittent intubation, jet ventilation. It is not in the scope of this chapter to fully describe anesthetic technique for pediatric airway surgery.

45.8 Airway Safety

If the appropriate setting for performing safe airway surgery is lacking, transferring the patient to an appropriate center should be considered including intubation or tracheotomy to secure the airway for transport.

45.9 Stages of Surgery

Setup for standard airway surgery: Setup should include preparation of endotracheal tube (ETT) in place over a narrow (2.7–2.9 mm) rigid endoscope, should urgent intubation be required during the procedure.

Tooth guard in place: Use an intubation blade laryngoscope to gain direct vision of the larynx.

Application of topical lidocain 2% at a volume of 0.2 mL/kg to supraglottis and glottis.

Preceding suspension laryngoscopy, perform preliminary rigid endoscopic examination with 4 mm 0 degree optics with blade laryngoscope to assess laryngeal structures, rule out any unexpected anomaly, ⁴¹ observe degree of obstruction in order to allow anesthesiologist a view of the airway.

Perform suspension laryngoscopy with a supraglottoscope (Benjamin-Lindholm laryngoscope or Parson laryngoscope) to achieve optimal exposure of the entire pharyngolarynx allowing surgical access to all supraglottic structures. The laryngoscope must be carefully positioned with the anterior blade in the vallecula, so as not to distort the epiglottic position or form. In order to achieve optimal exposure of the entire surgical field one may at times need to adjust degree of neck extension, at times removing extension totally. One may also apply pressure to the anterior neck at the cricoid level (similar to Selik maneuver) to help bring anterior laryngeal structures into direct view. This maneuver may be sustained during surgery by applying tape across the neck securing this position.

Once optimal exposure has been obtained, the airway should be examined by rigid endoscopy including the subglottis and trachea to rule out additional airway lesions. ^{31 , 42}

Bring the operating microscope with 400 mm lens into place. We find the work with the CO₂ laser most accurate with minimal collateral damage for supraglottoplasty. This surgery has also been described using cold metal instruments, microdebrider, and coblation, and the surgeon must choose the tool he is most comfortable with and the tool that in his hands brings the best results. ^{43 , 44}

As mentioned the surgery is best performed under general anesthesia with spontaneous breathing without an ETT. Due to the small size of the larynx when an ETT is in place the structures may be distorted and access to precise areas of resection difficult and therefore it is not recommended. Ideally, spontaneous breathing can be maintained with oxygen applied through side piece of suspension laryngoscope and/or via nasal airway. Another technique is to operate in an apneic state using intermittent intubation to re-oxygenate the patient. In this technique careful intubation is required with a small ETT (at least 0.5 of size less than the estimated ETT size for this patient).

When working with CO₂ laser, all necessary safety precautions must be taken, including covering the patient’s exposed areas with wet drapes or gauze, using safety goggles, etc.

Use of the CO₂ laser may begin after reduction of O₂ supply when anesthesiologist confirms FIO₂ drops below 40% to prevent potentially disastrous airway fire, and give OK to proceed.

CO₂ laser settings: Superpulse mode. Continuous or 10 Hz repetitious rate. Power should be set at 1.5–2.5. An additional suction should be placed through laryngoscope to evacuate smoke from laser use.

The tools used to manipulate the mucosa to be resected to bring in line with the laser include microlaryngoscopic triangular lt/rt graspers, micro-Hartman (alligator) forceps, laser-protected suction tube, as needed.