Transpalatal Advancement Pharyngoplasty

1

Indications

Wake clinical examination and endoscopy, sedated endoscopy, cephalometric x-rays, computed tomography and magnetic resonance imaging scanning, and fluoroscopy are used to assess differences in patient airways. In sleep apnea the obstruction is not a “fixed obstruction” but is a dynamic obstruction where vulnerable anatomy contributes to collapse. Abnormalities may include cross-sectional airway size, shape, curvature, and compliance. These can be described by pharyngeal airway phenotypes. Mueller maneuver and other methods assess the airway at “chokepoints” (points of minimal cross-sectional size). These fail to measure other airway segments that are critical to determining airway collapse. In addition to the chokepoint, the shape is critical. Narrowing may be anteroposterior (coronal) or lateral to lateral (sagittal). Proximal anteroposterior or lateral to lateral collapse cannot be easily addressed by traditional UPPP techniques ( Fig. 38.1 ). A narrow anterior to posterior airway at this level indicates retromaxillary airway narrowing or proximal retropalatal anatomic stricture and may be considered for palatal advancement.

Because swallow may be affected by palatal surgery, endoscopic attention to lateral wall motion with swallow can be done. Impaired lateral wall motion may increase the risk of swallow dysfunction postoperatively. Patients at high risk of pharyngeal swallowing dysfunction (abnormal endoscopic exam, symptomatic dysphagia, velopharyngeal insufficiency [VPI], presbyesophagus, severe reflux, and anterior cervical spine surgery) may benefit from additional medical and/or radiologic assessment of swallowing. Fortunately, most palatal and maxillary advancement is not associated with clinical worsening of dysphagia.

The oropalatal airway is also assessed because the palate relative to the palate is pulled forward with the procedure. A small oropalatal airway space may be worsened. The oropalatal airway is assessed with routine oral examination. A modified Mallampati 1 or 2 position indicates excellent oropalatal airway space. Patients with a modified Mallampati score of 3 and 4 may have a risk of worsening oral airway resistance after surgery.

Contraindications for the procedure include partial or complete cleft palate, swallowing dysfunction with poor lateral wall movement, a large torus palatini (requiring removal before advancement), VPI, obligate mouth breathers (may worsen oral breathing), those who have severe gag, or patients unable to accept the recovery from a complication. Maxillary advancement with Le Fort osteotomies may, in rare circumstances, damage the greater palatine vessels and worsen the blood supply to the maxilla. Those likely to undergo maxillofacial surgery should have the issue of avascular necrosis discussed. Prior radiation, tissue ablation (sclerotherapy or radiofrequency), and patients with extensive small vessel disease (diabetes, heavy smokers) may increase the risk of wound breakdown. Surgeons should also have adequate resources to address oronasal fistula.

2

Surgical Technique

The goal of the surgery is to expose the posterior hard palate to allow for an osteotomy and removal of bone. The medial and lateral soft palates are advanced and the wound closed. The advancement alters airway curvature and anteroposterior depth and decreases compliance of the lateral retropalatal wall. The procedure is performed under general anesthesia. An oral endotracheal tube is preferred as it is outside the surgical field. When using a nasotracheal tube, it is protected by placing a narrow malleable retractor along the floor of the nose. This instrument physically protects the endotracheal tube when the mucosa is cut with cautery and when the palatal drill holes are created for suture placement.

Patients are placed supine (in the Rose position if tonsillectomy is also to be performed), and operative exposure is obtained with a Dingman mouth gag. The Dingman mouth gag may facilitate handling of multiple sutures during the procedure, but its larger size provides more space for instrumentation. Perioperative antibiotics (such as cefazolin 1–3 g and metronidazole 500 mg) and dexamethasone 10 mg are administered. For hemostasis, 1% lidocaine with 1 : 100,000 epinephrine is infiltrated into the exit of the greater palatine foramen, the planned incision sites, the junction of the hard and soft palate, and the lateral tensor aponeurosis surrounding the hamulus. Nasal mucosal vasoconstriction is augmented with oxymetazoline-soaked pledgets placed along the floor of the nose.

Several types of palatal incisions have been described, including an “omega arch” or “propeller-shaped” incision. Both create two lateral and one posterior flap. Both are positioned so that the tip is 10 mm anterior to a line connecting the greater palatine foramen. The propeller incision has an advantage of a “V” in “Y” closure but the disadvantage that more of the incision overlies the osteotomy. The omega arch is centered more anteriorly and better covers the osteotomy but is vulnerable to distal tip ischemia. For both incisions, it is critical that elevation be performed laterally to expose the hamulus. The tensor tendon can then be identified and divided at its insertion onto the hamulus. This lateral division exposes the lateral nasal wall mucosa, which is then incised, and reduces the risk of fistula. The lateral incisions are placed medial to the greater palatine foramen and then directed laterally to expose the hamulus. A vertical midline incision from the tip of the flap anterior toward the incisor teeth allows better elevation of two lateral flaps with improved exposure of the hard palate.

The posterior flap is elevated back to, but not beyond, the junction of the hard and soft palate. During elevation, the proximal hard palate mucosa is thin, and care must be taken to avoid tearing. Laterally and posteriorly, the flap is thicker with more fibroadipose tissue. This can be bluntly dissected with a medium-sized mastoid curette. The lesser palatine vessels and nerves are divided. Bleeding is controlled with bipolar or suction cautery and use of vasoconstrictors with local injection. The tendon and periosteal attachments of the soft palate at the posterior edge of the hard palate must be preserved.

The “osteotomy method” leaves a small sliver (1–2 mm) of bone at the posterior edge of the hard palate. The hard and soft palates are separated with an osteotomy but in such a way that a narrow strip of bone is left at the junction. This preserves the periosteal and ligamentous attachments of the soft palate on the bone and provides a stronger closure. A transverse cut is made on the posterior hard palate using a 4-mm rotary diamond drill. A width of approximately 10 mm proximal bone is removed. Two millimeters of posterior bone attached to the soft palate are preserved. Copious irrigation prevents thermal damage to surrounding soft tissues. After the osteotomy, the posterior bone segment is still attached laterally to the palate and dorsally to the nasal septum. Lateral bone cuts are performed to separate from the palate and dorsally from the septum. This can be done with a small drill bit or heavy scissors.

The nasal mucosa is initially maintained intact but is later incised to mobilize the palate. First, a right-angle elevator back-elevates the nasal mucosa off the floor of the nose and allows for the transpalatal sutures to remain submucosal. Bovie cautery then cuts the mucosa posteriorly immediately next to the osteotomized bone segment. Mucosal attachments to the nasal septum are cut. Bleeding from the posterior septum may require use of suction cautery for control. If the procedure is performed with a nasotracheal endotracheal tube, the mucosa should first be cut on the side opposite to the tube.

Palatal drill holes are placed at a 45-degree angle to the palate, extending from the oral surface of the palate into the nasal cavity. The drill holes are 3 to 4 mm proximal from the osteotomy to prevent fracture of the bone around the suture holes.

The soft palate must be mobilized to allow for advancement. The tensor aponeurosis is cut at its insertion on the hamulus. Tendonolysis with electrocautery or sharp dissection and bipolar cautery are performed. When the aponeurosis is cut, a small “fat pad” medial to the hamulus and lateral to the nasal/nasopharyngeal mucosa is exposed. A Freer elevator in this space easily dissects the mucosa off the lateral nasal wall. The lateral nasal mucosa is then incised. This important step differs from prior descriptions where the nasal mucosa was incised more medially. Experience demonstrated that the more medial placement increased the likelihood of wound breakdown in this area and subsequent oral nasal fistula. The lateral incision of the nasal mucosa avoids this.

Two braided sutures (0 Vicryl on a UR-6 needle) are passed through each of the drill holes into the nasopharynx and then around the osteotomy. One is placed medially and a second laterally. For structural strength, sutures must include the tendon (aponeurosis) and not just the fibroadipose tissue. All four sutures are tied while an assistant pulls the palate forward with a blunt retractor.

Excess or redundant tissue of the palate is present after advancement. Because the posterior flap is thicker and has more fibroadipose tissue, judicious thinning is needed, but the mucosa is not trimmed, as this is needed for a “tensionless” closure. With the “propeller” incision the posterior flap may be pulled anteriorly in a “V” and “Y” advancement flap. The initial wide lateral elevation of the palate mucosa makes closure easier. The mucosal flap is closed with absorbable sutures. Suture placement may be difficult, especially with a high, arched hard palate.