When the length of resection of upper- or midtrachea is so great that anastomosis cannot be completed without excessive tension, anatomic release of the larynx to allow it to devolve distally may provide the necessary additional relaxation. Ogura and Roper described cutting the "ribbon muscles" of the larynx to achieve more mobility after a partial cricoid resection.6 Two principal methods described were thyrohyoid release, proposed by Dedo and Fishman,7 and suprahyoid release, developed by Montgomery.8 The length of release which results varies individually, but is not great. In practice, between 1 to 2 cm may be expected from this maneuver alone. However, even 1 cm represents nearly 10% of the trachea's length.
Zitsch and colleagues more optimistically measured anatomically a tension-free drop of 1.5 cm with suprahyoid release and a total of 2.0 cm with additional division of the inferior constrictor muscle from the thyroid cartilage.9 When a tension of less than 1,700 g was applied, a gain in length of 3.5 cm and 4 cm, respectively, was found. Clinical application was not described. The effect on deglutition is hence unknown. Other combinations of release have also been proposed, including infrahyoid and inferior constrictor release10 and intralaryngeal division of the thyroid cartilage.11 These last two methods were described in small numbers of patients. I have had no experience with these three techniques.
Laryngeal release is a useful procedure for extended upper tracheal resection and it may also contribute in a lengthy resection of the midtrachea or, on rare occasions, in a lower tracheal and carinal resection which extends to the midtrachea. However, I learned from experience that laryngeal release contributes nothing to low tracheal resection or carinal resection. The relaxation afforded by laryngeal release simply does not transfer all the way to the lower trachea. This was confirmed experimentally by Valesky and colleagues.12
Laryngeal release is not necessary routinely in tracheal reconstruction, as was advocated.7 Indeed, in 521 operations for postintubation stenosis, including 53 re-resections, laryngeal release was employed in 49 patients.4 Laryngeal release was understandably more frequently necessary in secondary operations (29% versus 6.4% in primary operations). In 80 laryngotracheoplastic resections for stenoses of varying etiology, only 7 releases were necessary.13 Seven laryngeal releases were performed in 89 tracheal resections and 19 laryngotracheoplastic resections for primary tracheal and secondary tumors.14
Thyrohyoid Laryngeal Release. I initially used the "Dedo" release technique for thyrohyoid laryngeal release.7 In this technique, the thyrohyoid muscles and the thyrohyoid membrane are divided above the thyroid cartilage, after retracting the sternohyoid and omohyoid muscles, and the superior cornua of the thyroid cartilage are detached to permit the larynx to drop (Figure 24-18). Great care is taken not to injure the internal branches of superior laryngeal nerves, which lie just behind and medial to the superior cornua of the thyroid cartilage. In a limited personal experience, most patients had significant postoperative difficulty in swallowing, some with aspiration. Patients gradually overcome this disability. F. G. Pearson (personal communication) reported a similar experience. I then moved to the "Montgomery" release technique.8 Fewer patients have had difficulty with aspiration following this method of release. Those who do are often older and, of course, have needed extended resections. These are precisely the patients most likely to need release. Nearly all patients overcome their aspiration problem with time and with assistance (see Chapter 21, "Complications of Tracheal Reconstruction").
In Surgery of the Larynx and Trachea published in 1990, Dedo no longer described the thyrohyoid release, instead presenting the suprahyoid technique which "releases the larynx just as well as the thyro-hyoid membrane technique and probably minimizes the risk of injury to the superior laryngeal artery and vein and the internal nerve branch."15 His technique is therefore presented here for completeness only.
figure 24-18 Thyrohyoid laryngeal release procedure. Technique ofDedo and Fishman.7 A, Exposure of the larynx between retracted sternohyoid muscles. The thyrohyoid muscles are divided at the upper edge of the thyroid cartilage, and the superior cornua of the thyroid cartilage are divided. The internal branch of the superior laryngeal nerve and the superior laryngeal artery are medial to the cornu and must be carefully avoided. B, The thyrohyoid ligament and membrane are opened transversely. Note the artery and nerve described in the legend for A.
Suprahyoid Laryngeal Release. Since I prefer to use a low collar incision for tracheal resection and reconstruction, rather than a higher incision or a U-shaped flap, I make a second short transverse incision directly over the hyoid bone (Figure 24-19A). This combination of incisions affords good access for the release and the reconstruction, and at the same time is more cosmetic. The incision for release is carried directly down to the hyoid bone. The superior surface of the central hyoid is exposed and dissection is carried laterally (Figure 24195). The tendons of the stylohyoid muscles attaching just below the sling for the digastric muscle are divided on either side. The digastric sling is left intact. All muscles attached to the hyoid between the two digastric slings, including the tendons of chondroglossus muscles to the lesser cornua of the hyoid bone, are detached. These are the mylohyoid, geniohyoid, and genioglossus (Figure 24-19C). I have found it convenient to do this with cautery, although this makes definition of the individual muscles less clear. The hyoid bone itself is divided lateral to the lesser cornu and medial to the digastric sling on either side (see Figure 24-19C). The preepiglottic space is widely opened (Figure 24-19D). Dissection, subcutaneously on the suprafascial plane to join the two cutaneous incisions, adds nothing to the release. A flat suction drain is placed in the preepiglottic space and the incision is closed in two layers. Immediate closure of the incision is important because it becomes inaccessible after completion of the tracheal anastomosis, when the neck is placed in flexion.
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