If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. You will then receive an email that contains a secure link for resetting your password
If the address matches a valid account an email will be sent to __email__ with instructions for resetting your password
Address reprint requests and correspondence: Christopher J. Hartnick, MD, Department of Otolaryngology—Head and Neck Surgery, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114
Subglottic stenosis represents a challenging problem in pediatric otolaryngology. A multidisciplinary care team is required to achieve successful outcomes. The primary therapy is surgical in nature. Expansion laryngotracheal reconstruction represents the primary surgical modality. Over time, advances in laryngotracheal reconstruction techniques and postoperative management have lead to excellent overall outcomes towards a primary goal of decannulation of tracheostomy dependent children. Recent efforts have been directed towards improving voice outcomes and devising less invasive procedures. Although the management of pediatric subglottic stenosis remains complex, most children can be successfully decannulated with proper surgical management.
popularized the concept of prolonged nasotracheal intubation to manage reversible pulmonary disease in neonates. The concept revolutionized neonatal critical care and the management of premature babies. However, upon widespread acceptance of the technique, a marked increase in the development of acquired neonatal subglottic stenosis (SGS) became evident. As the problem of neonatal SGS became more common and better defined, surgical care and procedures were developed and adapted from procedures in adults. Ultimately this led to the landmark airway expansion technique of placing cartilaginous grafts between the vertically divided cricoid lamina as reported by Fearon and Cotton.
The development of expansion laryngotracheal reconstruction (LTR) ultimately ushered the modern era of pediatric SGS management.
From an anatomic standpoint, the laryngeal inlet of an infant is shaped like a funnel leading to the trachea with the narrowest portion at the subglottis. The subglottis is at the level of the cricoid cartilage and represents the only portion of the airway that is circumferentially surrounded by cartilage. The narrow lumen and inability to expand secondary to the cricoid ring places the subglottis at particular risk for instrumentation injury.
SGS exists as congenital or acquired forms. Congenital SGS represents a continuum of incomplete or altered embryologic recanalization of the primitive laryngopharynx. This can range from complete failure of recanalization to a mild shape disturbance. Acquired SGS represents any form of stenosis that is not congenital in nature. The most often implicated cause is injury secondary to endotracheal intubation. Regardless of the cause, most children with SGS have tracheostomies placed to bypass the subglottis and subsequently present with tracheostomy dependence.
Over time, outcomes for LTR have increasingly improved toward a goal of decannulation. Overall decannulation rates range from 72% to 97% dependent on severity of stenosis with somewhat lower single operation specific rates.
Recent advances in the management of SGS are primarily aimed at improving voice outcomes and developing less invasive techniques.
Indications
Expansion LTR is primarily used in pediatric subglottic or posterior glottic stenosis. The presence of a congenitally narrow subglottis vs a purely acquired stenosis secondary to intubation injury can produce a variety of configurations with varying degrees of complexity. In general, LTR is performed for a mature stenosis with a firm fixed scar or a congenitally narrowed cricoid ring. Unlike resection methods of managing SGS (such as cricotracheal resection), expansion LTR techniques are not limited by extension of the stenosis to the vocal folds. LTR can be performed even if the scar approximates the vocal folds or is isolated to the posterior glottis. Another important indication for expansion LTR is bilateral vocal fold immobility with or without posterior glottic stenosis that is associated with respiratory insufficiency.
Staging
The ultimate goal of most airway reconstructive surgery is decannulation. Steps toward decannulation can proceed in a single setting or be approached in a staged manner. Single stage procedures refer to cases when decannulation is planned as part of the reconstructive procedure. A double stage procedure is one in which decannulation is planned at a future time under standard protocols after the airway has healed and can be clearly examined. The initial experience with LTR in children was with a double stage approach. In general, this approach is the most conservative route. Naturally, staging the procedure results in a longer period with a tracheostomy and possibly a suprastomal stent in place. Subsequently, the single stage LTR was conceived to achieve early decannulation by allowing for an endotracheal tube to serve as a short-term stent.
In general, lower grade stenosis tend to fare better from a single stage approach. Of note, single stage approaches require meticulous postoperative care in a pediatric intensive care unit (PICU) to maintain a secure position of the endotracheal tube. Early decannulation with a single stage procedure avoids the associated risks of PICU admissions that are frequently greater than 1 week.
Although each procedure is tailored to the specific preoperative endoscopic findings, the basic surgical intervention remains the same. All procedures begin with a diagnostic endoscopy to confirm the previous diagnosis and preoperative plan. Preoperative coordination with the anesthesia provider is essential. Specifics regarding the postoperative plan must be discussed particularly whether the child will have a tracheostomy or be intubated orally or nasally after surgery.
A transverse skin incision is used to expose the proximal trachea, cricoid, and thyroid cartilages. If a double stage procedure is planned, the incision is above and does not communicate with the tracheostomy site. If a single stage procedure is planned, the tracheostomy site is incorporated into the incision. A midline vertical incision through the anterior cricoid provides initial access to the airway. The midline incision is carried inferiorly through several tracheal rings. At this time, the stenosis is evaluated and the decision to proceed with an expansion procedure vs a cricotracheal resection is made. If an expansion procedure is selected, the incision is then carried superiorly and under direct visualization of the vocal folds, the thyroid cartilage is split in the midline precisely through the anterior commissure to allow complete visualization of the stenosis (Figure 1).
Figure 1Exposed laryngotracheal skeleton with midline anterior cricoid split and laryngofissure. Inset: endoscopically assisted incision of the anterior commissure.
A stepwise approach to the anterior commissure is prudent as a precise laryngofissure is a critical aspect of voice preservation. Initially, the thyroid cartilage is split vertically in the midline to the depth of the deep perichondrium. Subsequently, the perichondrium and mucosa is incised in an inferior to superior direction. The vocal folds must be clearly visualized to proceed superiorly and assure division at Broyle's ligament. If direct visualization of the vocal folds is limited secondary to anatomy or in revision surgery, an assistant performs a laryngoscopy and directly views the anterior commissure with a 4 mm telescope connected to a video camera (Figure 1, inset). The surgeon can then confirm the location of the incision on a video monitor and ensure a precise cut through the commissure.
At this time, a midline vertical division of the posterior cricoid lamina is performed through the scar and cartilage with care taken not to incise the common wall between the airway and the esophagus (Figure 2A). The deep edge of the divided cartilage is subsequently elevated from the common wall with an otologic elevator to effectively create pockets laterally between the deep surface of the posterior cricoid plate and the esophageal tissues. Measurements of the height of the posterior plate and the desired amount of distraction are obtained.
Figure 2Posterior cricoid split and graft placement. (A) Exposed airway with posterior cricoid split. (B) Placement of posterior cartilage graft.
The previously prepped chest is then exposed, and a costal cartilage graft is subsequently harvested from the fourth or fifth rib maintaining the integrity of the deep perichondrium. The wound is irrigated and a valsalva is performed to ensure that the pleura has not been violated. The chest wound is closed in layers with a rubber band drain in place. The costal cartilage is mannered to provide distraction of the vertically divided posterior cricoid lamina. The preserved perichondrium is maintained on the intraluminal side of the graft and flanges are carved on the deep surface. A classic “boat” shape may be used or a simple rectangular block with a central distraction block with lateral flanges provides excellent results.
The split posterior cricoid lamina is distracted with right angle forceps. One flange of the graft is placed within the previously developed pocket and using a gentle, but firm motion the contralateral flange of the graft is snapped into position (Figure 2B). The size of the graft varies according to the degree of stenosis and quality of harvested rib. Ultimately the graft should provide approximately 3-5 mm of distraction, and the flanges should allow a tight secure fit when placed into the previously elevated lateral pockets. If there is a secure fit, no sutures are required.
According to the postoperative plan, a stent mannered from an age appropriately sized t-tube is placed or the child is nasotracheally intubated. Stents are secured with heavy prolene suture passing through the thyroid ala and the strap muscles ultimately being tied just under the skin in a superficial position of the wound to allow easy removal during a postoperative bronchoscopy. Threading the suture through a cut angiocatheter is useful to prevent the suture from pulling through the strap muscles. The laryngofissure is then meticulously closed. A 6-0 Monocryl (Ethicon, Somerville, NJ) suture is used in a mattress manner to precisely reapproximate and resuspend the anterior commissure (Figure 3, inset). The cartilage is then reapproximated with 4-0 Vicryl (Ethicon, Somerville, NJ) sutures. Subsequently, an anterior graft is placed in a similar manner to the posterior graft except that the graft is secured with sutures to the vertical anterior cricoid split (Figure 3). The anterior and posterior distraction of the cricoid effectively increases the diameter of the subglottis based on the width of the grafts (Figure 4). The wound is then closed in layers with placement of a rubber band drain to serve as a conduit for a potential air leak. The child is then taken to the PICU for recovery. Variations include the use of alternative donor sites (thyroid ala, auricular cartilage, and septal cartilage), staging, type and duration of stenting, and using only an anterior or posterior graft.
Figure 3Reapproximated laryngotracheal skeleton with anterior graft in place. Inset: endoscopic view of the anterior commissure reapproximation and resuspension. Note mattress suture technique.
A key concept in preserving a child's voice during airway reconstruction is maintaining the integrity of the anterior commissure of the vocal folds. In some select cases, posterior grafting can be accomplished without extending the thyroid cartilage incision above the level of the vocal folds. However, as depicted above, a laryngofissure is requisite often to provide adequate exposure. In cases where a laryngofissure is necessary and the vocal folds are not clearly visualized, the technique of endoscopic assistance is invaluable. The precise incision is necessary to allow the careful reapproximation that is a cornerstone in voice preservation. Potential outcomes of a poor reapproximation include a vocal fold height mismatch, blunting of the commissure, or a complete avulsion.
Balloon dilation
In recent years, a resurgence of interest in balloon dilation techniques has evolved both as an adjunctive and primary therapy for SGS. Common uses of balloon dilation include perioperatively and postoperatively after dividing thin webs or thin stenoses. In our practice, we have found balloon dilation to be an invaluable adjunct in the immediate postoperative phase of open airway reconstruction. Previously, soft stenoses and granulation tissue were dilated in the early postoperative phase by successively up sizing endotracheal tubes. This is associated with a motion parallel to the subglottic mucosa and thus may lead to a shearing injury. Alternatively, balloon dilation is associated with a radial expansion and is theoretically less damaging to the subglottic tissues. Our experience is with the controlled radial expansion pulmonary balloon system (Ref Number 5033, Boston Scientific, Corp, Natick MA). The balloon system can be expanded to 8, 9, or 10 mm based on the inflated pressure. Markings on the balloon allow for precise placement where expansion occurs. The catheter is endoscopically placed during laryngoscopy with the stenosis aligned between 2 black markings on the catheter representing the inflation region (Figure 5). The balloon is then inflated using saline and the provided pressurizing device. Depending on the extent of stenosis and desired expansion, saline is instilled at 3, 5.5, or 9 atm of pressure. We typically hold expansion for 10 seconds and perform 3 cycles pending the status of the child's airway and whether a tracheostomy is present. While the balloon is inflated a 4 mm, telescope can be placed on the superior side of the balloon to allow a clear visualization of the region being dilated. This modality has salvaged what appeared to be previously unsalvageable restenoses and has become integral to our management of SGS.
Figure 5Coronal view of stenosis with balloon catheter in position and cross section of stenosis to denote direction of expansion forces. Superior extent of stenosis is to the level of the vocal fold inferior surface. (A) Before expansion. (B) Post expansion with endoscope viewing through balloon. Note region of expansion is between black markings on catheter.
The antifibroblast factor mitomycin-C has a mixed track record regarding use as an adjunct in airway surgery. Topical application has demonstrated safety in both ophthalmology and otolaryngology.
Several small case series have suggested decreased restenosis rates, however neither animal models nor a randomized trial have clearely demonstrated a benefit.
At this time, the expected benefit seems to be marginal. Of note, there has been report of superior success rates in a canine model with a different antifibroblast factor, chitosan.
introduced the endoscopic posterior cricoid split as an alternative to managing isolated posterior glottic stenosis or bilateral true vocal fold paralysis. The basic premise is to accomplish posterior expansion of the cricoid with an endoscopically placed costal cartilage graft. The procedure involves harvesting a rib graft in similar manner as described above. A temporary tracheostomy is placed in children who are not tracheostomy dependent. Subsequently, suspension microlaryngoscopy is performed and the larynx is exposed. At that time, self-retaining vocal cord retractors (Karl Storz, GmbH # 8654 B) are used to retract the false vocal folds opening the glottis widely to allow clear visualization of the posterior glottis and subglottis (Figure 6A and B). The interarytenoid fibers are split with a CO2 laser. A microlaryngeal alligator is subsequently used to further retract the interarytenoid fibers and dissect between the posterior cricoid and esophageal tissues. The incision proceeds in a posterior–inferior direction with the CO2 laser until the anterior mucosa, posterior scar, and posterior cricoid plate are divided (Figure 6B). Microlaryngeal alligators allow retraction of the superior side of the incision and the inferior extent to be completed. Once the incision is complete, the previously harvested graft is carved in similar manner to open procedures except that a small anterior flange or gentle dovetail configuration is added to the intraluminal side of the graft. A “safety suture” is passed through the graft to prevent it from becoming a foreign body. The graft is subsequently grasped and inserted into the split cricoid with microlaryngeal forceps (Figure 6C). A secure friction fit is expected provided the graft is of adequate size. Children are observed in the PICU postoperatively and ultimately undergo decannulation through standard protocols.
Figure 6Endoscopic posterior cricoid split with grafting. (A) Endoscopic view of glottis before placement of vocal fold retractors. (B) Endoscopic view of glottis with vocal cold retractors and completed posterior cricoid split. (C) Posterior graft in place.
In the postoperative period, recovery occurs in the PICU in a multidisciplinary manner. Children are placed on antibiotics and an antireflux regimen. Nebulized topical combination antibiotic/steroid preparations may provide some benefit, but are not routinely used. Our typical protocol is to remove the stent or endotracheal tube on postoperative day 7-10. At that time, the subglottis is generally widely patent. The child is subsequently scheduled for a repeat endoscopy 1 week later. Upon return, if there is any evidence of returning stenosis, a balloon dilation is performed and the child is reevaluated in 1 week. We have had success with salvaging restenosing airways with successive balloon dilation up to a month postoperatively.
Complications
Complications have been classified as intraoperative, early, intermediate, or late postoperative and because of a single stage procedure.
Intraoperative complications are technique driven and include pneumothorax during rib harvest or distal tracheal mobilization. Air leaks, hematomas, wound infections, pneumonias, or excessive granulation may develop during the PICU stay. A particular emphasis is placed on educating the critical care staff of the configuration of the airway and action to take in the event of an accidental decannulation or extubation. Supraglottic prolapse, anterior glottic webbing, a persistent tracheocutaneous fistula, poor voice, or restenosis may develop over time. The most important aspect of managing complications is early recognition as many of the complications described can be simply remedied when identified early.
Conclusion
SGS represents a challenging problem from a multidisciplinary context. Expansion LTR serves as the primary definitive surgical intervention. Over time, LTR procedures have been refined and an increasing interest in postoperative functional outcomes is becoming evident. Further investigation of techniques and adjuncts will serve to realize improved outcomes beyond merely decannulation. Although SGS remains a complex multifactorial problem with multidisciplinary considerations, it can be expected that with proper surgical management most children can be successfully decannulated.
The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, the Department of Defense, nor the USA Government.
00074-8&id=gr1.jpg){kind=link}
00074-8&id=gr2.jpg){kind=link}
00074-8&id=gr3.jpg){kind=link}
00074-8&id=gr4.jpg){kind=link}
00074-8&id=gr5.jpg){kind=link}
00074-8&id=gr6.jpg){kind=link}