Disclaimer: The information contained within the Grand Rounds Archive is intended for use by doctors and other health care professionals. These documents were prepared by resident physicians for presentation and discussion at a conference held at Baylor College of Medicine in Houston, Texas. No guarantees are made with respect to accuracy or timeliness of this material. This material should not be used as a basis for treatment decisions, and is not a substitute for professional consultation and/or peer-reviewed medical literature.

Subglottic stenosis is a disorder that has become increasingly important for otolaryngologists. The relatively small size of the airway, combined with the subglottis being the narrowest point of the pediatric airway, predisposes infants and children to the condition. Small amounts of scarring result in significant airway obstruction.

Subglottic stenosis may be either congenital or acquired. The congenital form results from incomplete recanalization of the subglottic area during embryogenesis and has been recognized for many years. Acquired subglottic stenosis occurs after manipulation or insult to the airway, with endotracheal intubation being the most common cause in children. Endotracheal intubation has increased the survival of premature infants, but has increased the incidence of acquired subglottic stenosis. Many authors have studied the pathophysiology of acquired subglottic stenosis but no uniform theory exists.

Subglottic stenosis may be divided into soft tissue and cartilaginous stenosis. Soft tissue stenosis may result from granulation tissue, submucosal gland hyperplasia or submucosal fibrosis. Typically soft tissue stenosis is acquired. Cartilaginous stenosis is usually congenital and may be divided into cricoid cartilage abnormalities or a trapped first tracheal ring. Some cases of acquired stenosis may have a congenital component as well. Endoscopy may give clues to the type of stenosis, but definitive diagnosis can only be made postmortem by whole section mounts of the larynx, or at the time of laryngotomy.

The signs and symptoms of subglottic stenosis are related to the degree of airway obstruction. Severe cases may present with stridor and respiratory distress. Less severe cases may present with recurrent croup, with these patients remaining asymptomatic until a URTI causes additional swelling and airway compromise. Some children may be treated for asthma before the correct diagnosis is made. Children who are intubated may present with repeated extubation failures.

The evaluation of these patients begins with a complete physical examination of the upper aerodigestive tract looking for associated problems in the head and neck. It is especially important to carefully assess vocal cord function, which may be done with the fiberoptic nasopharyngoscope. Untreated problems at the glottic level may lead to failure of the subglottic repair.

Radiographic evaluation is helpful in the child who is not intubated. A lateral soft tissue x-ray demonstrates the site and length of the stenotic segment. In addition, each patient should have a chest x-ray to rule out other respiratory problems.

Endoscopy is the most important component in evaluating these patients. While anesthetized and breathing spontaneously, the patient is examined carefully to look at vocal cord mobility. The stenosis is examined, and the length, thickness and consistency of the stenosis is assessed. The remainder of the airway is carefully examined to identify any other abnormalities.

One problem in the evaluation of treatment for this disorder is the lack of a uniform grading system allowing quantification of stenosis. The most common system used to grade stenosis was devised by Cotton. In this system, a grade is devised based on the percent of laryngeal obstruction. Grade 1 lesion has less that 70% obstruction and Grade 2 has 70% to 90%. Grade 3 obstruction is greater than 90% but with an identifiable lumen present. Grade 4 is complete obstruction.

Management of subglottic stenosis is influenced by the characteristics of the stenosis and associated medical problems. Two basic approaches have been used for the management of these patients. The first uses a wait-and-see approach where the child is allowed to grow, and to see if patients can be decannulated without surgical intervention. This may work for mild stenosis but, for more severe cases, surgical intervention may be required. This is particularly true for acquired stenosis. Many authors advocate repair due to the significant risk of pediatric tracheotomy in children with obstructed airways. Fearon and Cotton found a mortality rate of 5.9% and Pashley had mortality of 24% in this group of patients. In addition, the obstructed airway prevents phonation and development of spoken language, causing developmental delays for these children. It is important to realize that before any treatment is initiated, the patient must be medically and physically able to be decannulated.

Treatment may be either endoscopic or surgical reconstruction. Early endoscopic treatment consisted of serial dilations. Endoscopic excision has been performed using microcauterization, cryosurgery, and electrosurgical resection. Currently the CO2 or KTP laser is the technique of choice allowing vaporization of scar tissue with precision, producing minimal damage to normal tissue.

Simpson et al reported the results of CO2 laser treatment of subglottic stenosis in 31 patients. All patients had previous tracheotomies. Treatment consisted of laser excision. Postoperative stenting was used in 27 patients. The stent was made of rolled silastic sheet and was left in place for to 6 to 8 weeks. Using this technique, they were able to successfully decannulate 25 patients (80.6%). Each patient that was decannulated required an average of 2.44 procedures. In this study they also identified factors associated with failure of the CO2 laser treatment, including loss of cartilage framework, circumferential scarring, interarytenoid scar formation, scarring wider than 1 cm in vertical dimension, bacterial infection, and exposure of the perichondrium.

Failure of the above methods requires an open procedure which may be divided into either an anterior or cricoid split procedure or more formal laryngotracheoplasty procedures.

The anterior cricoid split (ACS) procedure, originally described by Cotton and Seid in 1980, was for neonates who had failed extubation and were being considered for tracheotomy. This procedure consists of division of the cricoid and upper airway with stenting by an endotracheal tube for several days to allow subsequent extubation without tracheotomy.

No one is certain exactly how the ACS works but several mechanisms have been proposed. One theory is that interruption of the cricoid ring relieves compression of soft tissue between the endotracheal tube and cricoid cartilage, allowing restoration of circulation to the tissue and resolution of the edema. Another theory is that division of the cricoid increases the subglottic lumen, but this has not been demonstrated histologically in several postmortem cases. The cricoid edges tend to stay close together and approximate the normal cricoid size.

Success of the procedure depends heavily on patient selection. Cotton proposes the following criteria for this procedure: 1) no assisted ventilation for ten days before evaluation; 2) supplemental oxygen requirement of less than 35%; 3) no congestive heart failure for one month prior to evaluation; 4) no acute respiratory tract infections; and 5) no aerodigestive tract pathology, especially GE reflux. The major limitation of this procedure is the difficulty of finding patients who fulfill these criteria.

After performing a thorough laryngoscopy and bronchoscopy to rule out other airway problems, the patient is positioned as if for a tracheotomy. A horizontal incision is made across the cricoid cartilage and the strap muscles and thyroid gland are divided and retracted laterally to expose the upper trachea and larynx. An incision is made across the cricoid cartilage and up into the thyroid cartilage and down through the first and second tracheal rings. An appropriately-sized endotracheal tube, based on the infant's weight, is inserted into the trachea and the overlying skin is loosely closed with a small rubber band drain. The child remains intubated for 2 to 3 weeks.

Cotton reported his series of 91 patients undergoing the procedure from 1977 to 1990. In this series, 69.2% were extubated and 22% required tracheotomy. Deaths occurred in 8.8%, none of which were a result of the ACS procedure. Excluding the deaths, 75.9% were extubated. Similar success rates have been reported at other centers. Accidental extubation and atelectasis were the most common complications. One patient with wound infection developed necrosis of the cricoid and thyroid cartilage and required subsequent laryngotracheoplasty. Most of the other complications were easily treated.

Richardson and Inglis, at Children's Hospital and Medical Center of the University of Washington, modified the ACS procedure to include insertion of a cartilage graft. In a prospective study they were able to decannulate 89% of patients with the rib graft compared to 56% without a rib graft. The operative time was 40 minutes longer in the rib graft group, but there were no differences in blood loss or complications.

In older pediatric patients with higher grade stenosis, a laryngotracheoplasty is performed. These procedures may be divided into three groups. The first is the anterior laryngofissure, with or without cartilage grafts. The second is anterior laryngofissure and posterior division of the cricoid with insertion of cartilage grafts at either site. Four quadrant division of the cricoid cartilage may also be performed.

Anterior laryngotracheoplasty is performed for stenosis located in the anterior subglottis. Two different techniques have been described. Evans and Todd's initial procedure divided the upper trachea and cricoid in a castellated incision to allow expansion. Later Cotton described a technique of anterior division along with insertion of a cartilage graft without a stent. Muntz and Lusk compared both techniques in a matched retrospective study of 21 patients with comparable, previously unoperated subglottic stenosis. They found that the overall decannulation was equal between the two techniques but the time to decannulation was three times longer with the Evans-Todd laryngotracheoplasty. This difference was due to the increased granulation tissue. More recently, the technique has been modified into a one-stage procedure where the tracheotomy tube is removed at the time of the initial repair and the patient is extubated at 7 to 10 days. Several series have reported good results with this technique.

Combined anterior laryngofissure and posterior cricoid division was initially described in adults by Rethi in 1956 and more recently has been used in children. This technique is best used for combined posterior glottic and subglottic stenosis, moderate subglottic and upper tracheal stenosis with loss of cartilaginous support, or circumferential stenosis. Cartilage grafts may be inserted at either site with or without a laryngeal stent. Zalzal reported the results of using anterior and posterior cartilage grafts in 41 patients. He was able to decannulate 90% of his patients with this technique, with a low complication rate. More recently, this technique has been used in a one-stage repair without laryngeal stenting.

Four quadrant division of the cricoid may be necessary for patients who have failed previous repairs. This is needed because the cricoid has lost its normal pliability and will not allow dilation to provide an adequate airway. To avoid injury to the recurrent laryngeal nerves it is important to make the later division precisely. The larynx is then stented open for about six months. Cotton reported the results of four-quadrant division of the cricoid in 31 patients. In this series 58% were extubated after the initial procedure and 76% were eventually decannulated after a second procedure. The mean duration of stenting was 6.6 months (1.2 - 12.6 months). Patients who had undergone previous open laryngotracheoplasties were the most difficult to decannulate, with an overall success rate of 62%, including all revisions.

Cotton et al reported the largest series of patients undergoing laryngotracheal reconstruction. Over a period of 15 years, he performed procedures in 203 patients. The overall success rate was 92%, including patients who underwent multiple procedures. At TCH, Drs. Smith and Catlin reported a decannulation rate of 95%. Results are poorer with higher grade stenosis.

Laryngotracheal reconstruction provides a high rate of decannulation and allows re-establishment of airway function, but restoration of phonatory and swallowing function are important as well. Several authors have demonstrated that periods of aphonia may result in language delay. Sell and Martin perceptually analyzed the voice results in 16 children and found only 31% with an acceptable voice. The vocal pitch was low with a rough and breathy quality. Kearns et al found blunting of the anterior commissure, false cord phonation, anterior overfolding of the arytenoids and limited mobility of one or both arytenoids on fiberoptic laryngoscopy in this group of patients. Smith et al reviewed their series of patients to look for swallowing disorders. They found no long-term problems but several patients experienced problems while the laryngeal stent was in place.

Today, advances in laryngotracheal reconstruction allow decannulation of the majority of patients with subglottic stenosis. A careful preoperative evaluation, and good surgical technique are essential for decannulation. Future advances in the management of this problem will provide good phonatory function.

Case Presentation

The patient initially presented to the Otolaryngology service at Ben Taub General Hospital, at the age of seven months, with stridor. He was a former 29-week preemie who had been intubated for several weeks for hyaline membrane disease. Direct laryngoscopy and bronchoscopy revealed a tight subglottic stenosis and the patient underwent tracheotomy. Because of persistent pulmonary problems, further intervention was delayed until the age of 13 months. At that time a repeat direct laryngoscopy and bronchoscopy revealed an 80% circumferential subglottic stenosis. The remainder of the examination was normal. He then underwent laryngotracheoplasty with insertion of anterior and posterior cartilage grafts using costal cartilage. The tracheotomy was removed and the patient was intubated orally. He remained intubated for ten days following surgery. On the tenth postoperative day he had a good air leak and was extubated. He has maintained a good airway with no stridor following extubation and is currently in the hospital recovering.

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