Aspiration prevention surgeries: a review

Total laryngectomy (Fig. 1B) is indicated for advanced laryngeal and pharyngeal cancers; it was also the treatment of choice for intractable aspiration before the 1970s [14]. It allows a definitive separation of the digestive and respiratory tracts. The larynx is exposed and skeletonized, and pharyngotomy and definitive laryngeal removal are performed [15‐17]. Pharyngeal reconstruction is subsequently performed using direct closure, anterolateral thigh flap, free jejunal flap, or other techniques depending on the indication [18, 19]. Total laryngectomy is performed under general anesthesia; it is not commonly performed under local anesthesia. Total laryngectomy is a globally common procedure that can be performed by several head and neck surgeons. It is not recommended if there is a possibility of laryngeal function improvement since it is irreversible.

Central-part laryngectomy (CPL) (Fig. 1C) is a type of narrow-field laryngectomy procedure first reported in Japan [20]. It is less invasive than total laryngectomy and involves the removal of the cricoid cartilage with the glottis, cutting the cricopharyngeal muscle, but preserving the epiglottis, the entire hypopharyngeal mucosa and major vessels and nerves running into the larynx [20]. CPL was proven to be effective in preventing aspiration pneumonia and may improve oral nutrition by reducing the resting upper esophageal sphincter (UES) pressure and prolonging UES relaxation during swallowing [21‐24]. CPL is an effective procedure for patients with diseases such as amyotrophic lateral sclerosis, which is characterized by reduced general muscle strength or pharyngeal contraction during swallowing that makes passage of food boluses from the pharynx to the esophagus difficult.

Lindeman in 1975 described a diverting procedure using a tracheoesophageal anastomosis for intractable aspiration (Fig. 1D) [25]. He initially performed the procedure on six mongrel dogs with successful outcomes. The procedure is usually performed under general anesthesia and involves dividing the trachea horizontally between the second and fourth tracheal rings. The proximal tracheal segment is anastomosed in an end-to-side fashion to an anterior esophagotomy. The distal tracheal segment is sutured to the anterior cervical skin, creating a tracheostomy. This technique has the following advantages: it allows secretions and orally ingested substances that have passed into the larynx to drain into the esophagus; tracheal reconstruction for reversal of the aspiration procedure is easier with the long proximal segment than with the short subglottic tracheal segment of the laryngotracheal separation (LTS) [4, 25, 26]. However, it is important to ensure that adequate tension-free anastomosis can be performed. If a high tracheostomy hole has already been created, which will prevent a tension-free anastomosis, LTS is preferred [4, 5, 27]. Although swallowing function did not improve after surgery, oral intake was possible, even for patients who presented with aspiration during pharyngeal swallowing and no swallowing reflex [17, 28, 29].

Lindeman described a modified tracheoesophageal diversion procedure in 1976, the following year described tracheoesophageal diversion [30], which is now called laryngotracheal separation (Fig. 1E). LTS became popular globally and has been performed for several patients with intractable aspiration, including children and adults [30‐34]. The procedure may be performed under local or general anesthesia. The trachea is divided between the second and third rings or at the level of the pre-existing tracheostomy, and the proximal trachea is closed anteroposteriorly over several layers. The distal tracheal segment is sutured to the inferior skin flap to create a wide tracheostomy. When a tracheostomy has been previously performed, LTS is recommended over tracheoesophageal diversion [4]. Avoiding tracheoesophageal anastomosis makes the procedure quicker and easier. No problems related to pooled material in the proximal pouch were encountered [4, 34]. There is also no risk of esophageal scarring, which can contribute to swallowing difficulties, since the esophagus is not breached. It is well accepted by patients and their families because the larynx is preserved [6].

The tracheal closure or tracheal flap method was described by Ninomiya et al. in 2008 (Fig. 1F) [35]. A U-shaped flap of the tracheal anterior wall from the second to the fourth or fifth tracheal ring is created, bent toward the tracheal lumen, and sutured to the tracheal posterior/lateral walls by mattress stitches for tracheal closure. In addition, the closure was covered with a cutaneous U-shaped flap for reinforcement, and a permanent tracheal stoma was constructed. The main characteristic of this technique is the absence of tracheal transection. In tracheoesophageal diversion/LTS, the transected trachea is above the tracheal stoma. Therefore, a tracheal cannula may come into contact with the upper tracheal rings, which sometimes causes postoperative complications such as granulation and fistulation [36].

Shino et al. reported three subtypes of the tracheal flap method [37]: anterior tracheal flap, which is used for closure of the trachea for patients without previous tracheostomy (A-type); mucoperichondrial flap, which is used for patients who lack an anterior tracheal wall due to a previous tracheostomy (B-type); esophageal flap, which is used for patients with a habit of continuous suctioning of saliva due to hypersalivation (C-type). In all three subtypes, the tracheal closure site is covered by an anterior cervical skin flap [37, 38].

Montgomery described the glottic closure procedure in 1975 (Fig. 1H) [45, 46]. During this procedure, the larynx is closed at the level of the true and false vocal cords. The larynx is opened via a midline thyrotomy, and the true and false vocal cords, ventricles, and the posterior commissure are denuded of the mucosa. Drawstring sutures are used to approximate the glottic surfaces for closure of the larynx, and a tracheostomy is necessary. Sasaki et al. modified the glottic closure procedure by adding a layer of laryngeal closure with a sternohyoid muscle flap [47]. Furthermore, advances in the prevention of postoperative stenosis of the tracheal stoma by combining partial removal of the cricopharyngeal cartilage with glottic closure [48, 49] and improvement of the passage of food through the upper esophageal portion by combining bilateral cricopharyngeal myotomy have been reported [22, 50]. The advantages of glottic laryngeal closure over total laryngectomy and tracheoesophageal diversion include a higher success rate for aspiration prevention, allowance of swallowing, and less invasiveness [49, 51]. Therefore, this procedure can be performed under local anesthesia for patients who are not good candidates for general anesthesia, such as patients with advanced head and neck cancers and neuromuscular diseases [21, 52‐56]. In addition, this procedure was reported to improve the quality of life by preventing aspiration pneumonia, improving oral feeding status, and reducing suction frequency [24, 49, 57].

Subglottic laryngeal closure may be the procedure of choice for the definitive separation of the upper alimentary and respiratory passages. During this procedure, the larynx is closed at the level of the subglottis (Fig. 1I). Eisele et al. described this procedure in 1995 [58]. They preserved the inner perichondrium of the cricoid cartilage, removed only the cricoid cartilage, and sutured the perichondrium at the subglottic level for the subglottic laryngeal closure. A permanent tracheostomy was created afterward. Later on, Miyake et al. [59] and Ueha et al. [21] modified the original method by leaving the posterior cricoid cartilage and adding cricopharyngeal myotomy. Subglottic laryngeal closure is possible under general or local anesthesia. Combined with a total cricothyrotomy or cricopharyngeal myotomy, the passage of the cervical esophagus is more likely to be improved [21].

Several authors have reported the use of endolaryngeal stents to prevent aspiration [60‐64]. These stents can be placed endoscopically, and the procedure is reversible with stent removal. A tracheostomy tube is necessary. The use of a vented silicone stent that permits phonation has been reported [64]. The disadvantages of using a stent to prevent aspiration include inconsistent outcomes due to leakage around the stent, the potential for endolaryngeal injury from the stent, and patient discomfort. Because of these drawbacks, the placement of endolaryngeal stents has failed to gain wide acceptance as a technique for the prevention of aspiration.

Vocal cord paralysis can result in chronic aspiration, particularly when combined with a laryngeal sensory deficit (e.g., a high vagal lesion) [65, 66]. This can be prevented with injection medialization laryngoplasty [67‐72]. To medialize the vocal cords, vocal cord injection can be performed endoscopically, transcervically, or transorally. Temporary vocal cord medialization can be achieved using hemostatic compressed sponge (Gelfoam, Pfizer, New York, NY, USA) [73], collagen [74], or autologous fat [75] for injection. Meanwhile, calcium phosphate [69, 76] and hydroxyapatite [77] are not easily absorbed and are suitable for those who desire a permanent vocal fold medialization effect. The latter is more suitable for preventing aspiration.

Laryngeal framework surgery, which involves medialization thyroplasty and arytenoid adduction, is another excellent technique for vocal cord medialization [69, 78‐80]. With medialization thyroplasty, Silastic (Dow Chemical, Midland, MI, USA) or another implant material is placed through a window in the thyroid cartilage to medialize the vocal cord. This procedure can be performed under local anesthesia, allowing tailoring of the implant shape and fine-tuning of implant placement while the patient phonates. Arytenoid adduction is also effective for medializing the paralyzed vocal cord, during which the arytenoid muscle is pulled across anteriorly by a suture until it is almost parallel to the lateral cricothyroid muscle. This is particularly helpful in closing posterior gaps between adducted vocal folds [81]. Postoperative swallowing studies have revealed the elimination of aspiration, enhanced pharyngeal clearance, and a capacity to liberalize bolus volume with consistency [78].