INDICATIONS/CONTRAINDICATIONS

Indications

Primary Endoscopic Treatment

Cautious carbon dioxide (CO₂) laser incisions combined with dilatation may be effective in treating thin, web-like cicatricial stenoses of the subglottis, but extensive laser resection is liable to make an acquired stenosis worse.

The indications described by Simpson et al. in 1982 are still valuable today as a basis for the endoscopic treatment of LTS. The CO₂ laser should be set to superpulse or ultrapulse mode, and the laser beam should be directed to the target with a microspot manipulator (250 μ spot size at 400-mm focal distance) to minimize heat diffusion into the surrounding tissue. Radial incisions in the stenosis are made using Shapsay’s technique, and gentle dilatation is done with tapered bougies or with angioplasty balloons. Next, a cotton swab soaked in a solution of 1 to 2 mg per mL Mitomycin C may be applied topically to the subglottis for 2 minutes. Repeated Mitomycin C applications should probably be avoided because of the uncertainty regarding possible late adverse effects.

Finally, if primary endoscopic treatment (CO₂ laser/dilatation/stenting) leads to a recurrence of the stenosis to its initial grade, then any further endoscopic treatment is strictly contraindicated. Open surgery should be considered instead.

Laryngotracheal Reconstruction with Cartilage Expansion (LTR)

This surgery is almost exclusively reserved for milder grades of pediatric SGS or for combined glotto-subglottic stenoses.

LTR with an anterior graft alone is used as a single-stage operation for the resolution of Grade II SGS. Mild Grade III stenosis is likely to need an anterior graft with posterior cricoid split supported by an endoluminal stent, and severe Grade III stenosis requires both anterior and posterior grafts with stenting. However, over the last decades, PCTR has been shown to be superior to LTR for the treatment of pediatric Grades III and IV SGSs.

In the case of congenital stenosis, the LTR may be combined with submucosal resection of cartilage to increase the size of a thickened anterior lamina of the cricoid ring.

PGS in children presents particular difficulties. A posterior cartilage graft is needed, but overexpansion of the posterior commissure should be avoided as it will impair voice quality and induce potential aspiration. Stenting is essential until complete healing of the glottis and subglottis has been obtained.

Partial Cricotracheal Resection (PCTR)

In infants and children, PCTR is the procedure of choice for the treatment of severe (>70% luminal obstruction) SGS of congenital or acquired etiology. PCTR is performed as a single-stage operation (with concomitant resection of the tracheostoma during the surgery) when the stenosis is purely subglottic, and the child is otherwise healthy. The only exception to this rule is a very distal location of the tracheostoma (fifth or sixth tracheal ring), with normal and steady tracheal rings available for the anastomosis between the SGS and the upper margin of the tracheostoma. The latter is then closed in a second stage.

In children with multiple congenital anomalies or with impaired neurologic or cardiopulmonary function, a double-stage PCTR (with postoperative maintenance of the tracheostoma) is preferable.

Extended PCTR

In the pediatric age group when an SGS is combined with glottic involvement such as posterior glottic stenosis (PGS), cicatricial fusion of the vocal cords, or distortion of the laryngeal framework resulting from failed LTRs, then PCTR is supplemented with a posterior cricoid split and costal cartilage graft that need stenting with an LT-Mold for about 3 weeks until complete healing of the subglottic area is obtained. The tracheostoma is then closed in a second stage. The alternative to this treatment is an LTR with anterior and posterior costal cartilage grafts with stenting, albeit with less chance of success, especially in severe stenosis grades.

Stenting

Laryngeal stents are mainly used to keep the airway expanded after surgical reconstructions involving the glottis (LTR with costal cartilage grafts or extended PCTR). They provide support for cartilage grafts, allow approximation and immobilization of mucosal grafts to the recipient site and maintain the lumen in a reconstructed area that lacks adequate support. Unfortunately, laryngeal stents can also act as foreign bodies in a reconstructed airway and induce mucosal injuries, ulcerations, granulation tissue formation, and subsequent restenosis if their anatomical conformity to the inner laryngeal contours is not perfect, or if their consistency is too hard. Several laryngeal stents are currently available on the market, but none of them truly meets the requirements for safe use without potential damage to the reconstructed airway.

To overcome this problem, the LT-Mold has been designed for the temporary stenting of the airway after surgical treatment of cicatricial stenoses of the larynx. Its design was created after molding cadaver larynges and increasing the interarytenoid distance to obtain the intralaryngeal contours of a fully abducted larynx. The prosthesis exists in 10 different sizes (from 6 to 15 mm in outer diameter), and four different lengths per size to accommodate the position of the tracheostoma with respect to the vocal folds.

Contraindications

Strict contraindications to an airway resection/reconstruction are rare. They are usually related to severe systemic comorbidities that cannot be corrected despite adequate medical or surgical treatment. These comorbidities comprise cardiopulmonary diseases with O₂ dependency, severe neurologic impairment or mental disability associated with pharyngolaryngeal discoordination and chronic aspiration during feeding, and finally severe maxillofacial abnormalities or multiple congenital anomalies.

Local factors affecting the airway, such as severe reflux laryngitis, a highly reactive larynx, an immature LTS, airway colonization with resistant bacteria, severe gastroesophageal reflux or eosinophilic esophagitis, and extralaryngeal sites of airway obstruction are all amenable to medical and/or surgical improvement prior to airway resection or reconstruction.

Gastroesophageal reflux should be treated with proton pump inhibitors or a fundoplication when deemed necessary; eosinophilic esophagitis confirmed by biopsy warrants full medical treatment prescribed by the gastroenterologist and the allergologist; airway colonization with MRSA, Pseudomonas aeruginosa or extended spectrum beta-lactamase (ESBL) requires a 5-day preoperative antibiotic prophylaxis based on bacteriologic cultures and sensitivities; a highly reactive larynx not responsive to antireflux treatment deserves a 3-month trial of Azythromycin (10 mg per kg bodyweight thrice weekly) as an immunomodulator to diminish the idiopathic chronic inflammatory reaction of the larynx; finally, an immature LTS only requires a waiting period before surgery is undertaken.

Most secondary dynamic airway stenoses usually benefit from surgical treatment: For instance, adenotonsillectomy for naso- or oropharyngeal obstruction; supraglottoplasty for laryngomalacia; maxillofacial procedures for craniofacial anomalies; and tracheomediastinal procedures for localized malacia related to the tracheostomy site, tracheoesophageal fistulae or vascular compressions of the airway, to mention but a few.

In summary, all efforts should be made to optimize the patient’s local and general conditions prior to any surgical intervention.

PREOPERATIVE PLANNING

A thorough endoscopic evaluation usually provides all of the information needed for careful planning of the surgery.

If precise description and measurement of the stenosis are obtained from the endoscopy, then radiographs add little to the preoperative workup. However, CT-scan with three-dimensional reconstructions is useful in documenting the length of the segment to be resected in case of complete airway obstruction. When a malformation of the mediastinum is suspected, computed tomography or magnetic resonance imaging are the examinations of choice.

Endoscopic Evaluation

Considering the potential dramatic consequences of a failed PCTR or LTR, careful attention should be given to the preoperative endoscopic workup. It should comprise a transnasal flexible laryngoscopy (TNFL) in spontaneous respiration, a direct laryngotracheoscopy in general anesthesia with suspension microlaryngoscopy (if needed), and a bronchoesophagoscopy.

Transnasal Flexible Laryngoscopy (TNFL)

In neonates and cooperative children, this investigation is done in the awake patient without sedation. This is the most effective way of assessing vocal fold mobility. In noncooperative children, TNFL under deep sevoflurane anesthesia with mask ventilation and spontaneous respiration is the preferred method. This examination not only gives information on the mobility of the vocal cords but also on the dynamic patency of the nose, the choanae, the nasopharynx, and the oropharynx. It must be pointed out here that anesthetic drugs can modify the interpretation of dynamic airway functions, hence the role of an experienced pediatric anesthesiologist to titrate the optimal depth of sedation for assessing vocal fold mobility. In the tracheostomized child, the cannula should be removed and the tracheostomy blocked temporarily to allow normal inspiration and exhalation, thereby allowing precise dynamic identification of intra- and extrathoracic malacic tracheal segments. If there is any doubt about the mobility of the vocal cords during transnasal fiberoptic laryngoscopy, then additional investigation in suspension microlaryngoscopy is mandatory.

Direct Laryngotracheoscopy and Suspension Microlaryngoscopy

Location, extent, and degree of stenosis are assessed using a bare magnifying telescope and the intubation laryngoscope while the patient is under general anesthesia and fully relaxed. The exact location of the stenosis with respect to the vocal folds, the tracheostoma, and the carina is given in millimeters. The degree of the stenosis is measured by passing telescopes, endotracheal tubes, or bougies of different given sizes through the stricture. In the pediatric community, the Myer–Cotton airway grading system is routinely used. This system classifies SGS into four grades and helps predict the rate of success after LTR because the less severe grades (I and II) have a far better outcome than do the severe grades (III and IV), which correspond to a subtotal or total obstruction. For PCTR, this grading system is not useful as a predictor of success or failure, because the stenotic segment is fully resected.

Differentiating vocal fold immobility due to a neurogenic cause from an interarytenoid fibrous adhesion is done by carefully inspecting the posterior commissure of the larynx, using a 30-degree, angled telescope and by direct palpation of the arytenoid cartilages during suspension microlaryngoscopy. The systematic use of Lindholm’s self-retaining vocal cord retractor (Storz no. 8654B) helps differentiate bilateral neurogenic vocal fold paralysis from PGS. A fixed arytenoid raises the suspicion of fibrous ankylosis of the joint, but in the most difficult cases, this diagnosis is only safely made during open surgery.

The endoscopy report should also mention the presence of any localized tracheomalacia as well as a possible infection of the airway. A bacteriologic aspirate of the trachea is routinely taken.

Bronchoesophagoscopy

In infants and children, this additional examination is mandatory in all cases of congenital SGS to rule out an associated mediastinal malformation (e.g., tracheoesophageal fistula, tracheobronchial anomalies, and extrinsic vascular compression of the airway), gastroesophageal reflux, or eosinophilic esophagitis.

SURGERY

Primary Endoscopic Treatment

These endoscopic techniques belong to the otolaryngologist’s armamentarium, but thoracic and pediatric surgeons should be cognizant of their therapeutic potential for addressing the challenging problem of cicatricial involvement of the glottis, such as PGS, vocal fold synechia, and cricoarytenoid joint fixation that are often associated with SGSs in the pediatric age group.

Strict adherence to proper indications, as previously described in this chapter, is a prerequisite to any endoscopic treatment.

The management of PGS requires expertise in the selection of the appropriate candidate for the right type of treatment. Interarytenoid adhesion with a residual posterior opening is usually not associated with cricoarytenoid (CA) joint fixation. Division of the scar with the CO₂ laser is thus the first appropriate choice of treatment with a potentially high success rate. True PGS without CA joint fixation should first be treated endoscopically with the CO₂ laser and adjuvant topical application of Mitomycin C. Five to seven days of postoperative intubation with a soft blue-line Portex tube help achieve a satisfactory result. The abductive force of both posterior CA muscles will prevent recurrence of the PGS, at least to some degree. In tracheostomized patients, 2 to 3 weeks of stenting with an LT-Mold ensures reepithelialization of the posterior commissure in the abductive position of the vocal folds, thus recreating an adequate airway for breathing. In cases of true fixation of the CA joints, a laser arytenoidectomy, a posterior cordotomy or a posterior costal cartilage graft should be envisaged. When PGS is combined with a SGS, open surgery is mandatory in most cases (see extended PCTR).

Laryngotracheal Reconstruction with Cartilage Expansion (LTR)

This operation is performed through a small collar incision placed at the superior edge of the tracheostoma. The strap muscles are separated from the midline to expose the anterior portion of the larynx and upper trachea.

For a Grade I or II SGS without glottic involvement, a simple LTR with anterior cartilage graft is usually sufficient. The vertical incision typically extends through the lower third of the thyroid cartilage, the thyrocricoid membrane, the cricoid, and the first two tracheal rings. The costal cartilage harvested from the fifth, sixth, or seventh rib is boat-shaped and placed with the perichondrium intraluminally, serving as a lattice for reepithelialization. Lateral flanges of cartilage to the inset portion of the graft are secured to the thyroid, cricoid, and tracheal rings with 4-0 Vicryl sutures, thus preventing prolapse of the graft into the airway (Fig. 37.1).

For an isolated PGS (without SGS), the anterior median incision is made as mentioned previously to gain access to the cricoid plate. The posterior cricoid split is made strictly in the midline, and the divided cricoid laminae are expanded laterally with a Cryle forceps. The scarred interarytenoid muscle should always be completely sectioned. The costal cartilage is shaped in a rectangular fashion with preservation of the posterolateral flanges. It is then snapped into position with the posterior flanges resting behind the divided cricoid laminae to avoid graft displacement.

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