Key Points
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Glottic and subglottic stenosis may arise from diverse etiologies that include, in descending order of frequency, iatrogenic causes such as prolonged endotracheal intubation or laryngeal surgery; external neck trauma; congenital stenosis; burns or caustic ingestions; infection; or inflammation, such as from gastroesophageal reflux or Wegener granulomatosis.
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Types of stenosis include anterior, posterior, circumferential, or complete.
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Glottic and subglottic stenosis may be prevented by repair of laryngeal fractures and lacerations, use of proper tracheotomy techniques and appropriate endolaryngeal surgery, and avoidance of intubation trauma.
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Diagnosis is made by history and physical examination; soft tissue anteroposterior and lateral imaging, computed tomography, and magnetic resonance imaging; and endoscopy (flexible and rigid). Additional evaluations may include pulmonary function tests, voice assessment, pH probe, and functional endoscopic evaluation of swallowing.
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Options for management include endoscopic approaches, anterior cricoid split, expansion surgery, grafting, stenting, single-stage laryngotracheoplasty, and partial cricotracheal resection.
Chronic laryngeal stenosis is a partial or complete cicatricial narrowing of the endolarynx that may be congenital or acquired. The condition is rare and presents multiple problems that affect soft tissue and cartilage. Iatrogenic injuries and external neck trauma account for most cases. Chronic laryngeal stenosis in pediatric patients may be managed differently from that in adult patients, but the principles of expansion versus resection surgery remain the same. Of all laryngeal stenoses, chronic subglottic stenosis (SGS) is the most common and presents significant challenges in management ( Fig. 26-1 ).
Etiology and Pathophysiology
Congenital Laryngeal Stenosis
Congenital stenosis is secondary to inadequate recanalization of the laryngeal lumen after completion of normal epithelial fusion at the end of the third month of gestation. The final pathologic findings depend on the degree of recanalization. Thus if the laryngeal lumen is not recanalized and remains completely obliterated, the result will be complete laryngeal atresia; if it is partially recanalized, incomplete atresia, stenosis, or webbing will occur. The cricoid cartilage is usually abnormally developed.
Congenital Laryngeal Atresia and Webs
Laryngeal atresia can occur at any laryngeal level or at a combination of levels. The clinical picture depends on the severity of the lesion. In complete atresia, the glottis is closed at or above the vocal cords by a firm fibrous membrane. The neonate is aphonic, tries vigorously to breathe, undergoes rapid deterioration, becomes cyanotic despite continued respiratory efforts, and soon dies of asphyxia unless immediate tracheotomy is performed. The condition is incompatible with life unless an emergency tracheotomy is performed or there is an associated tracheoesophageal or bronchoesophageal fistula. The most severe type of congenital laryngeal atresia presents as stillbirth and may not be recognized.
Congenital laryngeal webs account for about 5% of congenital anomalies of the larynx. About 75% occur at the glottic level, and the rest are supraglottic or subglottic. An association between anterior glottic web, chromosome 22q11.2 deletion, and velocardiofacial syndrome has been established. All patients with congenital anterior glottic web should have their chromosome 22q11.2 deletion status determined by standard fluorescent in situ hybridization analysis. Most webs present at birth or in the first few months of life. The severity of the web varies; only a few are severe enough to require airway support by intubation or tracheotomy. A laryngeal web is often an abnormality of the glottis and the subglottic cricoid region ( Fig. 26-2 ). The differential diagnosis includes bilateral vocal cord paralysis and congenital interarytenoid joint fixation. It is important to detect associated anomalies of the larynx, respiratory tract, and other organ systems.
Treatment of congenital laryngeal atresia and webs is presented later in this chapter under treatments for specific disorders.
Congenital Subglottic Stenosis
The normal subglottic lumen diameter in the full-term neonate is 4.5 to 5.5 mm; in premature babies, it is about 3.5 mm. A subglottic diameter of 4 mm or less in a full-term neonate is considered to be narrowed.
Subglottic stenosis (SGS) is considered to be congenital in the absence of a history of endotracheal intubation or other apparent acquired causes of stenosis. The diagnosis may be difficult to confirm, and it is unknown how many intubated premature infants who fail extubation have underlying congenital stenosis. Thus, by best approximation, congenital SGS is the third most common congenital disorder of the larynx after laryngomalacia and recurrent laryngeal nerve paralysis. Acquired SGS is more common than congenital stenosis because of the use of prolonged endotracheal intubation for respiratory support.
Congenital SGS is a clinical endoscopic diagnosis that describes various histopathologic conditions that produce narrowing of the subglottic airway. Congenital SGS can be divided into membranous and cartilaginous types. The membranous type is a fibrous soft tissue thickening of the subglottic area caused by increased fibrous connective tissue or hyperplastic dilated mucous glands with no inflammatory reaction. It is usually circumferential, with the narrowest area 2 to 3 mm below the true vocal cords, and it sometimes extends upward to include the true vocal cords. The cartilaginous types are more variable, but the most common type is a thickening or deformity of the cricoid cartilage that causes a shelflike plate of cartilage that partially fills the concave inner surface of the cricoid ring and extends posteriorly as a solid rigid sheet, leaving only a small posterior opening.
Symptoms depend on the degree of subglottic narrowing. In severe cases, respiratory distress and stridor are present at birth; in milder cases, the symptoms become evident during the first few weeks or months of life and present as prolonged or recurrent croup. The differential diagnosis includes subglottic hemangioma and subglottic cysts. Infants usually become symptomatic within 3 months of birth because of increased activity and increased ventilation requirements.
Minimal laryngeal swelling secondary to infection or endoscopy may precipitate airway obstruction because the cricoid cartilage limits the swelling of tissue in any direction except toward the laryngeal lumen at the expense of the airway. Therefore great care is needed when endoscopy is performed on these children to prevent trauma to the subglottic mucosa.
The endoscopic diagnosis is essentially by means of flexible fiberoptic endoscopy to assess vocal cord function and rigid endoscopy to assess the degree of anatomic obstruction. Postendoscopic edema is avoided by operating on a quiet, relaxed infant who is well oxygenated. Cooperation between the endoscopist and anesthesiologist is essential, as is gentle instrumentation, preferably with the rigid rod-lens system telescope alone without the sheath. If postoperative edema occurs, aggressive management should be started with cool mist racemic epinephrine by aerosol or intermittent positive-pressure breathing and a short course of high-dose intravenous corticosteroids.
Congenital SGS is most often less severe than acquired stenosis and may therefore be managed more conservatively. Some patients outgrow the condition. Management depends on the degree and severity of stenosis, the shape (whether the cricoid cartilage is normal or abnormal), and whether associated congenital anomalies are present.
Mild cases of stenosis are managed conservatively by watchful waiting and regular follow-up because many children outgrow the problem. During observation, vigorous medical management of viral infection is recommended. More severe cases that require airway support may be managed by tracheotomy and reconstructive repair or by single-stage laryngotracheal reconstruction (LTR) using costal cartilage grafting for expansion of the subglottic airway.
Acquired Laryngeal Stenosis
Trauma is the most common cause of acquired laryngeal stenosis in children and adults and may be external or internal.
External Laryngeal Trauma
Blunt trauma to the neck sustained during motor vehicle accidents injures the larynx when the anterior surface of the extended neck strikes the dashboard or steering wheel and causes a laryngeal framework fracture. This is more common in adults than in children, in whom the prominent mandible and relatively high position of the larynx protect the latter from injury. Fractures of the larynx occur secondary to in-home accidents when the neck is injured by striking a piece of furniture such as a coffee table. Chronic acquired laryngeal stenosis is a sequela of severe laryngeal trauma with fracture of the cricoid and thyroid cartilages, with or without displacement, or of inadequately managed early stages of laryngeal trauma.
Another mechanism of blunt laryngeal trauma, the so-called clothesline injury, occurs when a person riding a bicycle hits the anterior neck on a branch or clothesline, sustaining laryngeal fracture and thyrotracheal or cricotracheal separation. A patient may have a separation of the cricoid and trachea and still survive the injury. Penetrating wounds of the larynx are usually less common than blunt trauma and are more common in adults than in children.
Internal Laryngeal Trauma
Most cases of internal laryngeal injury are iatrogenic, secondary to prolonged endotracheal intubation, which is the most common cause of chronic laryngeal stenosis. Approximately 90% of cases of acquired chronic SGS in infants and children occur secondary to endotracheal intubation. The reported incidence of stenosis after intubation ranges from less than 1% to 8.3%. This rate is much lower than the 12% to 20% reported in the late 1960s and early 1970s because of recognition of the problem and institution of preventive methods. Despite improvement in neonatal care, the incidence has stabilized at around 1% over the past 10 years. These figures may underestimate the true incidence of the disease in the pediatric population because many infants who are intubated do not survive the primary illness. In addition, some acquired SGS may not be recognized unless an infection of the upper respiratory tract develops, or the patient requires reintubation later in life. The areas most commonly injured are the subglottic region in children and the posterior endolarynx in adults.
In children, the subglottic region is especially prone to injury from endotracheal intubation for various reasons. First, the cricoid cartilage is the only area in the upper airway that has a complete circular cartilaginous ring, which prevents the outward extension of traumatic edema. Second, the pseudostratified, ciliated, columnar respiratory epithelium lining this region is delicate and tends to deteriorate under the stress of an indwelling tube. Third, the subglottic submucosa is made up of loose areolar tissue that allows edema to develop easily and quickly. Fourth, the subglottic region is the narrowest portion of the pediatric airway.
The pathophysiology of acquired SGS is well described in the literature. The endotracheal tube (ETT) causes pressure necrosis at the point of interface with tissue, which leads to mucosal edema and ulceration. As ulceration deepens, normal ciliary flow is interrupted, with mucociliary stasis leading to secondary infection and perichondritis. With further infection, chondritis and cartilaginous necrosis occur, especially with collapse of the airway during inspiration. Healing occurs by secondary intention with granulation tissue proliferation in the areas of ulceration and deposition of fibrous tissue in the submucosa. Primary healing of the laryngeal injury is hindered by the presence of loose and mobile subglottic mucosa, poor blood supply to the cartilage, and constant motion of the larynx associated with swallowing and head movement. Study of intubated larynges from infants of 22 to 40 weeks’ gestation who survived a few hours to 300 days showed acute injury was almost invariable, and up to 100% of the subglottic epithelium was lost within a few hours of intubation, but progression of injury was relatively short lived. Ulcer healing started after a few days, rapidly progressed from day 10, and, in most cases, was complete after 30 days. This study suggests that long-standing acute injury of the subglottis is the exception, rather than the rule, even with the ETT remaining in place.
Duration of intubation and the size of the ETT are the most important factors in the development of laryngeal stenosis. No definite safe time limit for endotracheal intubation has been established. Severe injury has been reported after 17 hours of intubation in adults and 1 week after intubation in neonates. Several studies in adults have shown that a 7- to 10-day period is acceptable, after which prolongation of intubation is accompanied by an increased incidence of laryngotracheal complications. Premature infants tolerate more prolonged intubation (weeks rather than days). Explanations include the relative immaturity of the laryngeal cartilage in neonates (more hypercellular with scant gel-like matrix), which renders it more pliable and thus yielding to pressure, and the high location of the neonatal larynx in the neck with its posterior tilt and funnel shape.
Insertion of an oversized ETT increases the risk of laryngeal injury. In children, the tube size should allow an air leak at 20 cm water pressure if possible. Polymeric silicone and polyvinyl chloride are considered the safest materials for prolonged intubation.
Shearing motion of the tube causes abrasive traumatic action on the mucosa, especially in patients who are restless, those on respirators, and those with orotracheal intubation. Superimposed bacterial infection compounds the mechanical mucosal trauma by increasing the inflammatory response and scar tissue formation. Repeated intubations cause increased trauma and increase the risk of sequelae. Nasogastric tubes can cause pressure necrosis and cricoid chondritis if placed in the midline, and coexistence of endotracheal and nasogastric tubes may increase laryngeal complications.
When inexperienced personnel care for intubated patients, intubation complications may increase. Education of physician and nursing personnel who care for intubated patients markedly increases the expertise of that care. Systemic factors that include chronic illness, general disability, immunosuppression, anemia, neutropenia, toxicity, dehydration, hypoxemia, poor perfusion, radiotherapy, and the presence of gastric acid reflux encourage the vulnerability of laryngeal mucosa to injury by decreasing tissue resistance and increasing infection rate.
Other Causes of Laryngeal Stenosis
Laryngeal stenosis may occur secondary to laryngeal injury that results from laryngeal surgery. Emergency cricothyroidotomy through the cricothyroid membrane and high tracheotomy can produce severe stenosis, particularly in children. Supraglottic stenosis and collapse may be related to prior laryngeal or tracheal injury. Acquired anterior glottic web can occur after excision of a laryngeal polyp or papilloma in the anterior commissure area, if the anterior portions of both vocal cords are denuded simultaneously. Laryngeal stenosis also is described after endoscopic microsurgery with modalities such as electrocautery or laser.
Chondroradionecrosis can lead to scarring and stenosis shortly after radiotherapy or as much as 20 years later. Intralaryngeal burns from fumes, smoke inhalation, or caustic lye ingestion can also give rise to chronic laryngeal stenosis.
Chronic Infection.
Laryngeal stenosis secondary to chronic infection is rare except in isolated endemic geographic areas. It has been described in tuberculosis, syphilis, leprosy, glanders, typhoid fever, scarlet fever, diphtheria, mycosis, and laryngeal scleroma.
Chronic Inflammatory Disease.
Laryngeal stenosis has been described secondary to sarcoidosis, lupus erythematosus, Behçet syndrome, Wegener granulomatosis, relapsing polychondritis, pemphigoid, epidermolysis bullosa, amyloidosis, and major aphthous ulceration. Management of laryngotracheal stenosis in Wegener granulomatosis is complex and requires individualized and often multimodality interventions to achieve satisfactory results.
Chronic inflammation secondary to gastroesophageal reflux (GER) may cause laryngeal stenosis. GER in children can be classified as physiologic, functional, pathologic, or secondary. Many airway manifestations have been attributed to GER and include stridor, recurrent croup, exacerbation of SGS, and chronic cough. Diagnosis is difficult unless the index of suspicion is high. The role of GER on the outcome of pediatric LTR remains unknown. Until this is clear, we recommend that GER be investigated and treated in patients who undergo laryngeal reconstruction during the perioperative period.
Laryngeal Neoplasm.
Chondroma, fibroma, hemangioma, and carcinoma can cause laryngeal stenosis because of tumor infiltration or secondary to infective perichondritis, postradiation perichondritis, or postsurgical scarring and stenosis.
Types of Stenosis
Acquired glottic stenosis may be anterior, posterior, circumferential, or complete. Anterior glottic stenosis can be a thin glottic web, which is a bridge of scar tissue covered by epithelium located between the vocal cords involving the anterior commissure. This usually results from enthusiastic endoscopic surgery that involves both true cords simultaneously. Thick, anterior glottic scarring is usually more extensive and results in true vocal cords, false cords, and laryngeal ventricles adhering to one another without any intervening web. The cause is often unmanaged severe external laryngeal trauma. Posterior glottic stenosis usually results from prolonged ETT intubation.
Pressure necrosis of the mucosa that overlies the vocal process of the arytenoid occurs, followed by ulceration and granulation tissue formation on the medial surface of the body of the arytenoid cartilage. A similar process occurs to a variable degree in the interarytenoid area with involvement of the interarytenoid muscle, which causes fibrous ankylosis of one or both cricoarytenoid joints. Posterior glottic scar frequently extends downward to the subglottic region. It is important to differentiate between a complete posterior glottic stenosis, in which the scar is located in the interarytenoid space and posterior commissure, and an interarytenoid adhesion, in which the scar is between the vocal processes of the arytenoids with a small posterior, mucosally lined sinus tract in the posterior commissure area ( Figs. 26-3 and 26-4, A ). The scarring of the posterior commissure may be confined to the submucosa (see Fig. 26-4, B ) or may extend into one (see Fig. 26-4, C ) or both (see Fig. 26-4, D ) of the cricoarytenoid joints.
The voice is generally good because of the adducted position of the vocal cords. The major symptoms are referable to the airway. In mild or moderate cases, the patient may be able to ventilate without a tracheotomy and may experience only exercise intolerance. Patients who have a more severe stenosis may need a tracheotomy for adequate respiratory exchange. Diagnosis by indirect laryngoscopy is difficult and may be confused with bilateral vocal cord paralysis. Diagnosis at direct laryngoscopy is made by careful observation of the posterior commissure. The true vocal cords are closely approximated because the vocal processes, and occasionally the arytenoid bodies, are tethered together by heavy scar. A posterior sinus tract should be carefully sought and is particularly difficult to see in the pediatric larynx. Unlike vocal cord paralysis, in posterior glottic stenosis, the cricoarytenoid joints are partially or completely immobile on a passive motion test. Palpation of the arytenoids shows that they may be rocked in an anteroposterior direction but will not slide from side to side. Complete total glottic stenosis rarely occurs in isolation and is usually accompanied by supraglottic stenosis or SGS. In children, it is a sequela of endotracheal intubation, lye ingestion, and thermal burn.
Prevention
Factors important in reducing the incidence of laryngotracheal stenosis include:
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Early exploration of laryngeal fractures should be undertaken to minimize serious sequelae.
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High tracheotomy and cricothyroidotomy should be avoided except in extreme emergencies. If it is suspected that if a high tracheotomy or cricothyroidotomy has been performed, endoscopy is indicated. If the suspicion is confirmed, the neck should be explored, and the tracheotomy site should be relocated to a lower position to prevent chronic SGS. However, if a repair with a cricotracheal resection (CTR) is planned, a high tracheotomy—rather than a lower one—is advantageous because it reduces the length of the resection.
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When performing a tracheotomy, the surgeon should avoid extensive resection of the tracheal wall and should use the smallest size tracheotomy tube compatible with ventilation and suctioning.
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Aggressive endoscopy for benign laryngeal lesions should be avoided, especially for those in the anterior commissure area, to prevent formation of an anterior glottic web. The procedures should be staged 2 weeks apart for each side. Different principles may be appropriate for malignant lesions.
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Intubation and endoscopy should be performed gently on relaxed patients.
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Circumstances that contribute to laryngeal trauma secondary to prolonged intubation should be recognized and avoided whenever possible.
Diagnosis of Congenital and Acquired Laryngeal Stenosis
Laryngeal stenosis is diagnosed by a thorough history and physical examination, radiologic evaluation, and endoscopic examination of the airway and esophagus. Other investigations such as pulmonary function tests also may be helpful.
History and Physical Examination
Mild to moderate laryngeal stenosis is usually asymptomatic, until an infection of the upper respiratory tract causes additional narrowing of the airway and results in respiratory distress. These patients usually have a tendency toward prolonged courses of upper respiratory tract infections.
In acquired stenosis, a history of laryngeal insult is present. Symptoms usually occur 2 to 4 weeks after the original insult, although the latent period can occasionally be longer. In congenital stenosis, symptoms usually appear at or shortly after birth, which suggests the possibility of a laryngeal anomaly.
The main symptoms of laryngeal stenosis relate to airway, voice, and feeding. Progressive respiratory difficulty is the prime symptom of airway obstruction with biphasic stridor, dyspnea, air hunger, and vigorous efforts of breathing and suprasternal, intercostal, and diaphragmatic retraction. Abnormal cry, aphonia, or hoarseness occurs when the vocal cords are affected. Dysphagia and feeding abnormality with recurrent aspiration and pneumonia can occur.
Complete physical examination of the upper aerodigestive tract should be performed to rule out associated congenital anomalies or acquired injuries.
Radiologic Evaluation
Radiologic evaluation is performed after stabilization of the airway. Radiography helps assess the exact site and length of the stenotic segment, especially for totally obliterated airways. The soft tissue radiograph is the single most important view in children. The anteroposterior high-kilovoltage technique increases visibility of the upper airway by enhancing the tracheal air column while deemphasizing the bony cervical spine. In acquired stenosis, small areas of calcification may be seen, denoting the site of previous injury. Fluoroscopy is helpful in studying tracheal dynamics.
Computed tomography (CT) and magnetic resonance imaging are useful. High-speed CT has reduced the imaging time and is becoming more popular in the assessment of airway lesions. Magnetic resonance imaging still requires a significant amount of time, necessitating sedation in younger patients.
Evaluation of swallowing is important before airway reconstruction because dysfunctional feeding may complicate airway reconstruction by increasing the risk of aspiration postoperatively. Patients who undergo surgical correction of airway anomalies should have a historic screen for feeding problems. Patients with marginal feeding skills may be unable to compensate for the altered anatomy created by the reconstruction.
Videofluoroscopic swallowing studies (VSSs) provide radiographic reviews of the bolus during swallowing. The presence of laryngeal penetration and aspiration can be documented, and the ability of the child to protect the airway can be assessed. However, many children with congenital anomalies of the airway cannot tolerate the volume of contrast necessary to visualize the swallowing mechanism. In addition, many of these children were not exposed to nutritional stimuli at sensitive periods of their development, and they consequently acquired significant oral aversion behaviors that preclude the introduction of any material into the mouth. If it is not possible to assess swallowing safety by VSSs, an endoscopic evaluation of swallowing should be performed.
Endoscopic Examination
Indirect laryngoscopy alone is inadequate for diagnosis. Direct endoscopic visualization of the larynx is essential to study the stenosis carefully. Flexible fiberoptic endoscopy assesses the dynamics of vocal cord function and the upper airway, including the trachea. In patients with severe burns and neck contractures, flexible endoscopy may be the only method to visualize the larynx. Flexible retrograde tracheoscopy through the tracheotomy site may provide useful information in some cases.
Rigid and flexible endoscopy of the airway and esophagus should be performed in the operating room with the patient under general anesthesia. The rigid telescope is especially important in the examination of children because it better visualizes the small larynx. However, it is important to recognize that the airway lumen should be measured by passing bronchoscopes or ETTs of known sizes and cannot be gauged by the use of telescopes alone.
Flexible endoscopy and spiral CT with multiplanar resolution must be considered complementary techniques to rigid endoscopy in the preoperative evaluation and follow-up of children with laryngotracheal stenosis.
Evaluation of Gastroesophageal and Gastrolaryngopharyngeal Reflux
GER is a common occurrence in children and adults. Many infants have no pathologic symptoms related to GER (the “happy spitters”). The current prevailing, although not universal, opinion is that GER and gastrolaryngopharyngeal reflux (GLPR) may play a role in the development and exacerbation of SGS and may adversely affect the successful outcome of laryngotracheal reconstruction (LTR). GER and GLPR are defined as involuntary passage of gastric contents into the esophagus and pharynx and are commonly occurring physiologic phenomena. It is not the presence of reflux that determines gastroesophageal reflux disease (GERD) or gastrolaryngopharyngeal reflux disease (GLPRD) but rather the frequency, intensity, and associated symptoms of reflux that distinguishes GERD and GLPRD from GER and GLPR. Unfortunately, no gold standard exists for recognizing or excluding GERD and GLPRD, and differentiation between physiologic and pathologic reflux can be difficult. All diagnostic tests available for GER and GLPR have significant limitations. Generally, they tend to have high specificity but low sensitivity. Of the tests available today, a 24-hour esophageal pH probe using a dual-probe technique is believed to be the most reliable; when used in conjunction with the history, esophagoscopy, and esophageal biopsy, it yields the best information in determining the likelihood of GERD and GLPRD.
Esophagogastroduodenoscopy with Biopsy
Esophagogastroduodenoscopy (EGD) allows direct visualization of the esophageal, gastric, and duodenal mucosa and it facilitates biopsy of any suspicious lesions. Any esophageal mucosal irritation; erosion; ulceration; epithelial metaplasia, as in Barrett esophagitis; or stricture should be noted and biopsied. Histologic findings of esophagitis should be confirmed. EGD is a surgical procedure with its own potential risks of bleeding, infection, intestinal perforation, mediastinitis, and peritonitis. EGD is recommended when esophagitis is suspected, but it is not required for every patient who undergoes reflux evaluation. When esophagitis is detected, EGD with biopsy may be repeated to determine treatment efficacy.
It is important to recognize eosinophilic esophagitis as a separate entity from GER. Control of this condition is important prior to surgical reconstruction of the airway.
Treatment of GER and GLPR starts with dietary and lifestyle modifications and can be supplemented by pharmacologic agents. If control of GER and GLPR is not achieved with maximum medical therapy, a surgical consultation should be obtained. Proper communication among the otolaryngologist, gastroenterologist, and surgeon based on the previous investigations leads to institution of the most appropriate therapeutic program for the individual patient.
Functional Endoscopic Evaluation of Swallowing
The functional endoscopic evaluation of the swallow study requires the passage of a flexible endoscope transnasally into the hypopharynx. The hypopharynx can be visualized and parameters similar to those rated in VSS related to airway protection can be determined. In addition, secretions that spill from the oral cavity and pool in the hypopharynx may be visualized, and their aspiration risk can be assessed. An assessment of hypopharyngeal sensation also can be made by demonstrating the laryngeal closure response elicited from a calibrated air stimulus to the larynx. Decreased sensation is correlated with an increased aspiration potential. If VSS is precluded because of oral aversion, a functional endoscopic evaluation of the swallow study is performed.
Voice Assessment
Psychoacoustic evaluation and acoustic analysis of the voice may be used to establish the degree of vocal abnormality before surgery and compare it with voice analysis after surgery.
Although assessment of preoperative and postoperative vocal quality in young children may be frustrating, improvement in technology has made the task easier, and several reports have been published regarding specific voice issues. In general, the voice results are unsatisfactory, and the vocal parameters suggest a pattern of lower than optimum pitch and a restricted pitch range. The vocal quality appears to be disturbed in most patients; however, laryngeal reconstruction makes oral communication possible.
Pulmonary Function Test
Pulmonary function tests with spirometric maximum inspiration and expiration flow rates, flow volume loops, or pressure flow loops show characteristic changes in upper airway stenosis and can be used to compare the postoperative results with preoperative values.
Management
Management should be individualized according to pathologic findings, patient age, degree and consistency of stenosis (hard or soft and percentage of stenosis), and general condition of the patient. Management of adults differs from that of children, and some operations useful in children are not applicable to adults.
All cases of moderate or severe laryngeal stenosis require a tracheotomy at or below the third tracheal ring to establish a safe airway. Stenosis that does not require a tracheotomy constitutes a mild case. A four-stage grading system for stenosis has been widely adopted ( Table 26-1 ).
| Grade | Percentage of Laryngeal Lumen Obstruction |
|---|---|
| I | <70% |
| II | 70%-90% |
| III | >90%; identifiable lumen is present (no matter how narrow) |
| IV | Complete obstruction; no lumen |
Securing the airway is of primary importance if immediate repair cannot be performed. Severe cases of congenital SGS or marked cartilaginous cricoid deformity require a tracheotomy to maintain an adequate airway. When a tracheotomy is performed, the smallest tube that permits adequate ventilation should be used. The tube should allow air leakage to occur to avoid injury to the tracheal mucosa and simultaneously preserve phonatory potential.
Tracheotomy was required in congenital SGS in less than half of a large series of patients. Once the airway is secured, two basic management modalities are considered, either endoscopic or open. Endoscopic surgical methods include traditional dilation including balloon dilation and techniques that use laser excision of stenotic areas. Open surgical methods include expansion and resection surgery. The morbidity of open reconstruction is higher, but this is balanced against the multiplicity and futility of endoscopic procedures when inappropriately used. In general, less severe cases respond to endoscopic methods, and more severe cases require external reconstruction. If the cartilaginous framework of the larynx is significantly deficient, endoscopy is unlikely to be successful.
The best chance for the patient lies in the initial operation. Endoscopic techniques for isolated SGS may be successful in grade I and occasionally grade II SGS. Expansion laryngotracheal surgery is very successful in grade II and III stenoses and in some grade IV stenoses. Partial cricotracheal resection (PCTR) is successful in some grade III and IV stenoses, where there is a clear margin between the stenosis and the vocal cords. PCTR can be augmented by posterior cartilage grafting, especially when scarring reaches the glottis. Slide thyrocricotracheoplasty offers an efficient surgical treatment option with minimal morbidity for high-grade SGS.
Endoscopic Management
Dilation is sometimes useful early in the development of stenosis. It is not recommended for mature, firm stenosis or cartilaginous stenosis. Dilation is usually performed alone or is supplemented with local or systemic corticosteroids or intralaryngeal stenting. The use of corticosteroids in all stages of acquired SGS is controversial. Corticosteroids tend to decrease scar formation by their antiinflammatory action of delaying synthesis of collagen in early stages of wound healing and increasing collagen lysis in the later phases. Corticosteroids also delay wound healing by delaying the epithelial migration necessary to resurface the denuded area, thus increasing scar formation and predisposing to infection. Corticosteroids may be used systemically or locally. Local injection into subglottic scar is technically difficult and may be ineffective if a pressure injection system is not used. Resorption of cartilage secondary to the presence of local corticosteroids is a serious complication. Inhalation corticosteroids are believed to reduce granulation tissue formation after stent removal or early after ETT injury.
Mitomycin C is an antineoplastic antibiotic that acts as an alkylating agent by inhibiting deoxyribonucleic acid (DNA) and protein synthesis. Initial experimental animal studies and postendoscopic application seemed promising; however, there seems to be no advantage to its use after open surgical repair. Acute airway obstruction is a risk from excessive accumulation of fibrinous debris at the operative site in humans and animals after applying mitomycin to sites treated with carbon dioxide (CO 2 ) laser and dilation. Furthermore, a randomized prospective animal study has shown that mitomycin is limited in its effect on established wounds.
Endoscopic scar excision using the CO 2 laser is popular because it allows the surgeon to vaporize scar tissue with precision but produces minimal damage to healthy areas. Tissue destruction is directly related to the amount of energy delivered by the laser and the duration of exposure. If minimal energy of short duration is delivered, damage to the underlying and normal surrounding structures is minimal. However, if the laser is used at high energy levels for long times, it acts similar to any other uncontrolled method of tissue excision. The laser is useful for managing early stenosis with granulation tissue and may improve the airway without causing significant bleeding or edema, thus avoiding the need for a tracheotomy. Many authors have reported adequate results in managing early or mild SGS using the CO 2 laser, generally with multiple procedures; CO 2 laser treatment was found to be effective in 92% of grade I SGSs, but that declined to 46% in grade II SGSs and to 13% in grade III SGSs. To avoid worsening of the airway, it is recommended that CO 2 laser treatment be used only once, if the airway lumen does not improve. Fiber-based lasers such as thulium and CO 2 lasers are being used more frequently and provide good access and accuracy. Endoscopic management becomes less effective with worsening lesions.
The principles applied to endoscopic management should be also enforced for balloon dilation. Several studies have been reported with generally good results that are not universally achieved in SGS grades III and IV. Balloon dilation of the glottis, especially for posterior glottic stenosis, is not recommended. Endoscopic management is not successful in the presence of the following conditions:
- 1.
Circumferential cicatricial scarring
- 2.
Abundant scar tissue greater than 1 cm in vertical dimension
- 3.
Fibrotic scar tissue in the interarytenoid area of the posterior commissure
- 4.
Severe bacterial infection of the trachea after tracheotomy
- 5.
Exposure of perichondrium or cartilage during CO 2 excision (predisposes to perichondritis and chondritis)
- 6.
Combined laryngotracheal stenosis
- 7.
Failure of previous endoscopic procedures
- 8.
Significant loss of cartilaginous framework
Anterior Cricoid Split Operation
The anterior cricoid split operation ( Fig. 26-5 ) was described in 1980 as an alternative to tracheotomy in the management of acquired SGS in premature infants. The procedure has subsequently been used in the management of congenital SGS. The concept is to split the cricoid and upper first and second tracheal rings in the midline anteriorly, thus allowing expansion of the cricoid ring. It is indicated in cases of congenital SGS caused by a small cricoid ring (i.e., not otherwise seriously deformed) or extensive submucosal fibrosis with healthy cricoid cartilage. It should be used only in patients whose condition is severe enough to require airway support and in whom lung function is adequate to permit decannulation. Use of auricular cartilage, thyroid alar cartilage, and hyoid grafts has been reported to improve the success rate of the cricoid split operation. Many factors determine the success of the cricoid split procedure and hence the variability of its success, from a low of 35% to a high of 88%. Performing a cricoid split operation on a healthy infant with isolated SGS yields the best results. Poor results occur when patients are generally sick and the airway lesion is not restricted to the subglottis.
