Lateral pharyngoplasty

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Chapter 38 Lateral pharyngoplasty

3 SURGICAL TECHNIQUE

The procedure is performed with the patient under general anesthesia, using a mouth gag with a long tongue blade to give adequate exposure (Fig. 38.1). We use 4.0 Vicryl for all sutures. LP is performed as a stand-alone treatment for snoring and sleep apnea. When the patient needs nasal surgery to improve nasal breathing, this can be done in combination with LP. Fourteen per cent of our cases were treated with both LP and nasal surgery together.

LP starts with a bilateral tonsillectomy (Fig. 38.2). If that has already been done, we undermine and remove the tonsillar fossa lining until we can identify the palatoglossus and palatopharyngeus muscles. Next, with an upside down ‘V-shape’ incision (Fig. 38.3), we remove a triangle of mucosa and muscle (palatoglossus) from the lateral oral free margin of the soft palate and anterior pillar.That provides a wide exposure of the SPC muscle, including its pterygopharyngeal (partially), buccopharyngeal and mylopharyngeal parts (Figs 38.4 and 38.5). The height of this incision corresponds to that reached by the lateral superior traction (see Fig. 38.10) of the upper part of the palatopharyngeus muscle, which will be used to close this wound.

Once fully exposed, we undermine and elevate the SPC muscle from the peripharyngeal space (Fig. 38.6), starting from its most cranial visible part, and separate it from its fascia (buccopharyngeal fascia). It is very important to preserve this fascia, avoiding injury to cranial nerves IX and X and to other pharyngeal muscles, which could delay swallowing recovery. The SPC muscle is elevated from the pharyngeal wall in its posterior but not lateral aspect, near the palatopharyngeus muscle, since this region has fewer blood vessels, and once you reach the right plane of dissection there, the muscle can be easily detached from its fascia. Usually, the vertical fibers of the palatopharyngeus muscle have to be pulled medially at the start of the dissection, to expose better the horizontal fibers of the SPC. Once detached, we cauterize the SPC with a bipolar and section its fibers in a cranial to caudal direction (Fig. 38.7). We keep this dissection near the palatopharyngeus, using this muscle as a guide to avoid injuring vessels and nerves at the lateropharyngeal space. This dissection extends as far as the caudal end of the SPC muscle (glossopharyngeal part, where it originates from the side of the tongue). To accomplish this, we have to create a submucosal tunnel inferiorly to the tonsillar fossa to preserve and separate the mucosa from the SPC muscle that is being sectioned. This usually extends from 1 to 1.6 cm beyond the tonsillar fossa, depending on the anatomy, and relates to the retroglossal area.

When the section of the SPC is complete, we get two muscle flaps: one medially based flap that is not manipulated any further, and one laterally based flap that is sutured anteriorly to the same-side palatoglossus muscle with four or five separate stitches (Fig. 38.8). The glossopharyngeal part of the SPC does not need to be sutured. At the end of this suturing line, the peripharyngeal space is widely exposed and the lateral wall is splinted along all of the collapsible pharynx (Fig. 38.9). This surgical wound is then closed by pulling and suturing the palatopharyngeus to the remnants of the palatoglossus muscle (Figs. 38.10 and 38.11). The medial flap of the SPC is not included in this pull. Every step is then repeated on the opposite side (Fig. 38.12). At the end, due to the bilateral pull of the palatopharyngeus muscles, the uvula stays in the midline and sometimes it bends upwards, returning to normal within hours or days.

4 POSTOPERATIVE MANAGEMENT ANDCOMPLICATIONS

Extubation is delayed until the patients are wide awake with good muscle tone. The patients stay monitored in the recovery room for 1–2 hours before going to the ward, with the head of the bed elevated (usually 60°). When respiratory discomfort occurs, it is usually noted immediately after extubation. We have not observed this with this technique, but it did happen in some cases in which we used a Z-plasty instead of our current method of pulling the palatopharyngeus muscles in the lateral port areas. Also, we noted that the use of atropine at the end of the surgery produced a comfortable recovery, with reduced salivation.

The hospital stay usually lasts 1 or 2 days and discharge criteria include pain control and adequate oral intake of fluids. We use antibiotic coverage for 7 days (amoxicillin or azithromycin) and steroids (hydrocortisone, 200 mg intravenously every 8 hours during hospitalization . Additionally, we use painkillers (dypiron, 500 mg orally every 6 hours and, if needed, tramadol hydrochloride, 75 mg orally every 8 hours) and topical anesthetics (benzocaine 0.4%, four sprays in the throat up to four times daily), usually for 10 days after the procedures. The patients also receive gastric acid anti-secretory agents (pantoprazole or esomeprazole, 40 mg orally daily for 1–2 months).

Wound dehiscence typically occurs in the region of the caudal stitch of the tonsillar fossa some days after the surgery, requiring no attention. There is actually a dead space in the pharyngeal wall after LP, which is already drained to the airway lumen and heals during the first week. Postoperative pain is usually moderate and if abnormal, excessive pain arises, it should be treated with removal of the stitches in the area that hurts. Mild velopharyngeal insufficiency is common after LP, reducing gradually and usually disappearing after 2–4 weeks. Swallowing difficulties usually last 2–3 weeks and, after that, the patients are usually able to eat any kind of food with the eventual aid of liquids. Normal swallowing sensation usually takes 2 months to be restored. The majority of patients return to work 10–12 days after the procedure.

FURTHER READING

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Schwab RJ, Gupta KB, Gefter WB, et al. Upper airway and soft tissue anatomy in normal subjects and patients with sleep-disordered breathing: significance of the lateral pharyngeal walls. Am J Respir Crit Care Med. 1995;152:1673-1689.

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Woodson BT, Wooten MR. Manometric and endoscopic localization of airway obstruction after uvulopalatopharyngoplasty. Otolaryngol Head Neck Surg. 1994;111:38-43.