Posterior glottic stenosis is usually due to intubation, when an endotracheal tube lies in place too long or is too large a caliber, especially if the patient is awake and swallowing, because the natural point of maximum pressure of an oral endotracheal tube is at the posterior commissure of the larynx. Often, this problem is combined with a subglottic stenosis due to insertion of the too large endotracheal tube. From actual measurements done in anatomy laboratories, it has been shown that one should never use a larger than 6 mm endotracheal tube in a female patient. Many women can take larger than 6 mm, but a significant number have a cricoid lumen that will not permit larger than a 6 mm tube to pass atraumatically through it. Patients who have a prolonged intubation should be placed on medication to minimize gastric acid secretion, in case of gastroesophageal reflux. Reflux can lead to inflammatory changes that would add to those of intubation and help generate stenosis in the glottis and subglottis.
Other causes of stenosis are direct external trauma to the cricoid and/or thyroid cartilage and cricothyrotomy. Many advocate doing a cricothyrotomy as an emergency tracheostomy. It is a quicker way into the trachea with less bleeding, as it is closer to the surface, and one does not have to worry about the thyroid isthmus. A cricothyrotomy should always be converted to a standard tracheostomy as soon as possible. If left in place, the tube will erode the cricoid, and often the thyroid cartilage as well, leading to stenosis.
A posterior glottic stenosis is a band of scar tissue between the two arytenoids involving the mucosa and extending into the arytenoid muscle, preventing the vocal cords from abducting normally. It is often difficult to diagnose a posterior glottic stenosis with a mirror or a fiber-optic endoscope. One can be suspicious when the cords move briskly but not widely, as if tethered on a short cord. Usually, on direct laryngoscopy, when the cords are parted with the anterior tip of the laryngoscope, the stenosis can be readily seen as a thickened linear band of tissue between the arytenoids (Figure 35-3A). Laser division of this band is occasionally helpful, but usually open surgery is necessary. If a tracheostomy is not already present, one must be done. A laryngofissure is then performed through a horizontal incision over the midportion of the thyroid cartilage. The dissection is carried down to the strap muscles, which are separated in the midline. The perichondrium is incised in the midline. The cartilage is incised in the midline with a knife blade. If the cartilage is ossified, then it is cut with a Stryker saw (Figure 35-35). A button knife is inserted through a small incision in the cricothyroid membrane, dividing the mucosa in the midline. The thyroid laminae are held apart with a self-retaining retractor or with hand retractors held by an assistant. The web is identified visually, and to assess its extent, it is palpated in the area of the posterior commissure and is incised in the midline down through the scar into the interarytenoid muscle until all the fibrotic muscle has been divided (Figures 35-3C,D). A mucosal flap is then elevated from posteriorly over the arytenoid and the esophageal introitus, and is advanced to cover the raw surface in the interarytenoid space, and then sutured in place with a 4-0 chromic suture on a small half-round needle (Figures 35-35,5). This work can be performed with otologic instruments such as a Rosen or McHugh knife and canal wall or drum elevator. A stent is then inserted and the wound is closed. The thyroid laminae are closed by suturing the perichondrium edges together. A drain is inserted and the skin and subcutaneous tissues are closed in the usual fashion. Care is taken throughout this procedure to avoid connecting the laryngofissure dissection with the tracheostomy.
If the patient has a normal subglottis and trachea, then a solid Montgomery conforming laryngeal stent is used.6 The stent is held in place with a 2-0 nylon suture, placed through and through from externally and tied over plastic buttons (Figure 35-4). Several different size stents are available. This stent is left in place for 4 to 8 weeks and is then removed via a laryngoscope after first cutting and removing the nylon suture. It has the advantage of being a conforming stent and the disadvantage that the patient is totally aphonic while it is in place and totally dependent of the tracheostomy for airway. As the stent is solid, aspiration is prevented, which makes it more useful in patients who would be apt to aspirate, such as older patients and patients who have had a previous superior laryngeal release procedure. If the patient has sub-glottic disease that is going to be repaired later, or possibly was repaired at the same time, then a Montgomery T tube is inserted, with the upper end coming up through the vocal cords to the level of the laryngeal ventricle. The tube is cut to length and smoothed with a sander or a sterile emery board before it is inserted. The upper end should lie at the level of the laryngeal ventricle. This allows the false cords to close over the tube, preventing aspiration, and the patient is able to talk in a somewhat hoarse voice, phonating with the false vocal cords. In patients who have chondromalacia, granulation tissue, or some condition in the upper trachea that one wants to stent with a larger tube than will fit through the vocal cords, a tapered T tube works well (Figure 35-5). The lower limb is 13 mm in diameter to fit into the trachea, and the upper limb tapers to 10 mm at the level of the vocal cords.
figure 35-3 Posterior glottic stenosis. A, Laryngoscopic view of a posterior band between the arytenoids. B, Midline incision in the thyroid cartilage. C, Incision of web mucosa. D, Incision of scarred interarytenoid muscle. Incision of mucosa for advancement flap. E, Mucosal flap elevated. F, Mucosal flap advanced and sutured in place.
figure 35-4 A, Conforming stent in place with the small bulge into the ventricle between the true and false vocal cords, and the wider lower end through the cricoid ring into the upper trachea. B, Small adult (female) and large adult (male) stents. Also available are adolescent and child size stents.
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