Transpalatal advancement pharyngoplasty

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Chapter 36 Transpalatal advancement pharyngoplasty

B. Tucker Woodson

1 INTRODUCTION

The ultimate goal of surgical treatment for obstructive sleep apnea (OSA) is to improve symptoms and eliminate disease morbidity and mortality. This is accomplished by altering airway sizecompliance and shape. Successful surgery eliminates collapseairflow limitation and airway obstruction during sleep. The precise features of successful versus unsuccessful surgery remain poorly understood.

The retropalatal airway segment is a major contributor to airway obstruction in sleep apnea. Although uvulopala-topharyngoplasty (UPPP)as described by Fujitaremains the most common OSA surgeryit suffers from technical failures including inexact patient selectionincorrect and flawed techniqueand external factors such as infection. To address palatal failurea different approach is required.

Transpalatal advancement pharyngoplasty alters the retropalatal airway by advancing the palate forward. Hard palate is excised and a palatal advancement flap is created. It does not require excision of the soft palate. The palate is pulled forward and superior which conceptually is similar to maxillary advancement.

The procedure used alone or in combination with other soft tissue surgeries is indicated for sleep apnea patients having narrowing in the retropalatal airway. It is particularly useful when there is narrowing of the pharyngeal isthmus proximal to the point of palatal excision using traditional UPPP techniques. A transpalatal approach and advancement is also useful for obstructions in the nasopharynx (such as enlarged adenoids) that cannot be accessed through traditional techniques due to the difficult OSA anatomy.

2 SURGICAL TECHNIQUE

2.1 EVALUATION

Preoperativelynasopharyngeal endoscopy is currently the primary method of airway evaluation and is performed in both a sitting and supine body position. Features evaluated include sizeshapeareas of collapseand pharyngeal swallow. During endoscopyclose attention is focused on the size and the shape of the proximal pharyngeal isthmus. Narrowing of the airway proximal to this point of estimated excision of traditional UPPP is an indication for primary transpalatal advancement pharyngoplasty. The shape of the pharyngeal isthmus indicates whether narrowing is from anterior–posterior compression (transversely shaped) or from collapse of the lateral walls (sagittally shaped). The locations of the levator muscle and palatopharyngeal sphincter are identified by visualizing the anterior fold of the torus tubarus (torus levatorius) which leads to the position of the levator muscle in the soft palate (Fig. 36.1). A narrow anterior to posterior airway at this level indicates retromaxillary airway narrowing. Such an abnormality cannot be addressed by traditional palatopharyngoplasty without aggressive excision of the levator muscle.

Fig. 36.1 AMid-sagittal depiction of palate anatomy and demonstrating palatal advancement. The location of the palatal aponeurosis close to nasal mucosa is shown. The levator palatine muscle originates at the skull base and passes through the anterior fold of the Eustachian tube (torus levatorius) and into the palate and is a key determinant of palate position relative to the posterior pharyngeal wall. For advancementdrill holes are placed from the oral cavity to the nose anterior to osteotomy. A strong rim of bone supports sutures. The thicker posterior mucosa is shown. The anterior tip of the mucosal incision should be proximal to this and should be placed slightly proximal in the thinner palatal mucosa. BMucosa. After osteotomysutures are placed through the drill holes and the bone fragment with attached tendon and ligaments is advanced.

The retropalatal and retromaxillary airway is a fundamental abnormality of adults with sleep apnea. Normal upper airway shape and size must be learnedas well as patterns of stenosis and scarring of the retropalatal segment following palatal or tonsil surgeries. Swallow is also evaluated while performing endoscopy with specific attention to lateral wall motion. Impaired lateral wall motion may increase the risk of swallow dysfunction with any palatal surgery. Patients at high risk of pharyngeal swallowing dysfunction (abnormal endoscopic examsymptomatic dysphagiavelopharyngeal insufficiencypresbyesophagussevere reflux and anterior cervical spine surgery) need further swallow evaluation. Fortunatelyeven in patients who have had prior UPPPpalatal and maxillary advancement are not usually associated with worsening of dysphagia.

Evaluation of the oropalatal airway is also needed. Since the palate relative to the tongue base is pulled forward a small oropalatal airway space may be worsened. This requires additional surgery even if the pharyngeal retroglossal airway space is not severely abnormal. The oropalatal airway is assessed initially with routine oral examination. A modified Malampatti 1 or 2 position indicates excellent oropalatal airway space. Modified Malampatti 3 and 4 have a compromised oropalatal airway. Those patients with very small oral airways who are primarily mouth breathers need this segment treated prior to palatal surgery.

Contraindications for the procedure include partial or complete cleft palateswallowing dysfunction with poor lateral wall movementa large torus palatini (requiring removal prior to advancement)velopharyngeal insufficiencyobligate mouth breathers (may worsen oral breathing)those who have severe gagor patients unable to accept the recovery from a complication. Maxillary advancement with LeFort osteotomies may in rare circumstances damage the greater palatine vessels and the blood supply to the maxilla. Palatal and tonsil surgery may also impair collateral blood flow to the maxilla andin the rare event this occursincrease the risk of avascular necrosis. Those likely to undergo maxillofacial surgery should have this issue discussed. Prior radiationtissue ablation (sclerotherapy or radiofrequency)and patients with extensive small vessel disease (diabetesheavy smokers) may increase the risk of wound breakdown. Surgeons should also have adequate resources to address oronasal fistula.

2.2 THE PROCEDURE

The procedure may be divided conceptually into steps including: (1) incision; (2) flap elevation; (3) palatal osteo-tomy; (4) tendinolysis; (5) palate advancement; (6) wound closure; and if needed (7) distal palatopharyngoplasty or tonsillectomy.

The procedure is performed under general anesthesia delivered oro-endotracheally. Patients are placed supine in the Rose position if tonsillectomy is also to be performedand operative exposure is obtained with a Dingman mouth gag (Pilling Instrument Co.PhiladelphiaPA). The Dingman mouth gag facilitates handling of multiple sutures during parts of the procedurebut is not needed for exposure and a normal ‘tonsil gag’ may also be used. Perioperative antibiotics (cephazolin 1–2 g and metronidaizole 500 mg) and dexametasone 10 mg are administered. For hemostasis1% lidocaine with 1:100,000 epinephrine is infiltrated into the exit of the greater palatine foramenthe planned incision sitesthe junction of the hard and soft palateand into the lateral tensor aponeurosis medial to the hamulus. In addition to the injection of the hard and soft palatenasal mucosa is augmented with oxymetazoline soaked pledgets placed along the floor of the nose which reduce bleeding from the nasal mucosa when placing drill holes and sutures.

2.1.1 INCISIONFLAP ELEVATION

See Figure 36.2.

Fig. 36.2 Diagram of palatal advancement pharyngoplasty. AIncision placement with the omega shaped incision. Anteriorlythe incision is in thin palate mucosa proximal to anticipated bone removal. The incision is then placed medial to the greater palatine foramen and flares laterally posterior to alveolus towards the hamulus. BLateral flaps are elevated. The tip of the midline flap is planned to be 5 mm anterior to bone removal and is elevated just to the junction of the hard and soft palate. Care is taken to not separate the tendon attachments to the hard palate. Posterior elevation is exaggerated in the figure to depict anatomy. CSites of osteotomy are shown.

A palatal incision is outlined beginning at the central hard palate posterior to the alveolus. The anterior extent of the flap should extend approximately 5 mm anterior to the planned osteotomy. The incision is at the junction of the thinner palatal mucosa and the thicker fibroadipose and muscular layer (Fig. 36.1). The incision goes immediately medial to the greater palatine foramen and is then flared laterally at the junction of the hard and soft palate to extend laterally over the area of the hamulus. This results in a curvilinear ‘omega arch’ appearance. An additional incision extends vertically up the midline of the hard palate (‘T’ incision). This allows for laterally based flaps which allow for more lateral and anterior exposure of the hard palate and reduce the need for a longer midline flap which is at risk of tip necrosis.

Lateral flaps are elevated off the bone to expose the proximal hard palate. The midline mucoperiosteal flap is elevated back to the junction of the hard and soft palate. During elevationthe central mucosa is usually thin and care must be taken to avoid tearing it. Laterally and posteriorlythe flap is thicker. Medial and posterior to the greater palatine foramenthe fibroadipose tissue is thicker and it is best bluntly dissected to avoid damage to the greater palatine vessels (a small mastoid curette which has both a curved blunt surface and sharp edge works well). The lesser palatine vessels and nerves may be transected with flap elevation. Bleeding is usually minimal if adequate time for hemostasis has been allotted and postoperatively sensation to the palate returns. Elevation of the flap beyond the border of the soft and hard palate to expose the soft palate is avoided. Care is taken to preserve the tendon and periosteal attachments of the soft palate to the posterior edge of the hard palate. Flap elevation must remain superficial to the tensor aponeurosis.

2.1.2 OSTEOTOMY, MOBILIZATION, TENDINOLYSIS, ADVANCEMENT AND CLOSURE

See Figure 36.3.

Fig. 36.3 Diagrammatic procedure of transpalatal advancement pharyngoplasty (continued). AA posterior osteotomy is performed leaving a 1–2 mm rim of bone. Nasal mucosa is preserved at this point. Proximal drill holes are placed lateral to the septum and medial to the inferior turbinates. The soft and hard palate are separated exposing nasopharynx. The osteotomy is separated from the posterior nasal septum and lateral tendinolysis is performed. BSutures are placed through palatal drill holes and around the palatal osteotomy and into the tensor aponeurosis laterally. Posterior traction is used to advance the flap and sutures are tied. CMucosa is approximated with multiple interrupted sutures.

Two methods have been used to divide the hard and soft palate by separation with an osteotomy. The current method creates a small osteotomized segment that retains the peri-osteal and ligamentous attachments of the hard and soft palate. This osteotomy take a small additional time to perform but results in a stronger closure. Older methods that simply cut the soft tissue from the bone of the hard palate posterior junction using electrocautery required four to six sutures to close the wound and to advance the palate and were more traumatic to soft tissues. Oronasal fistula rates in the older technique were up to 10% or more. The ‘osteotomy method’ leaves 1 or 2 mm of bone at the posterior edge with attached periosteal and ligamentous fibers. Closure is stronger with only two sutures.

The hard and soft palates using a distal transverse osteo-tomy of the posterior hard palate 1–2 mm anterior to the soft palate using a small sagittal saw or drill. Lateral osteotomies are performed far laterally and as close to the alveolus as possible. A dorsal osteotomy with drill or heavy scissors separates the segment from the septum. The lateral and dorsal osteotomies are done with a small rotary burrsmall sagittal sawor heavy scissors. The tensor aponeurosis remains solidly attached to bone.

After the distal osteotomy is performed a posterior0.5–1.0 cm margin of the hard palate (palatine bone) is removed to provide space to move the soft palate anteriorly. Bone removal is performed with a rotary drill to remove residual bone and exposes the posterior nasal septum. Mucosa of the floor of the nose is kept intact at this point to allow for easier backwards elevation of the nasal mucosa off the floor of the nose. This elevation allows for the transpalatal sutures to remain submucosal. If not submucosalthere is a small risk of nasal granuloma in the postoperative period. Palatal drill holes are placed at a 45° angle to the palateextending from the oral surface of the palate into the nasal cavity. A strong segment (3–4 mm) of bone must be left between these drill holes and the excised bony margin. If the procedure is performed with nasotracheal intubationa small malleable retractor is placed in the floor of the nose for protection and drill holes and use of electrocautery must be done with caution to avoid damage to the tube.

The soft palate must be mobilizedto allow palate advancement. The tensor tendon is incised laterally medial to the insertion on the hamulus. Tendonolysis includes both the tensor tendon and if needed fascial bands of the anterior belly of the levator palatini muscle (Fig. 36.4). Visual-izing the nasopharynx is important to identify the lateral nasopharyngeal walls and other landmarks and to avoid inadvertent dissection and trauma into the lateral wall of the nasopharynx. Nasal mucosa is incised (with electrocautery) proximal and lateral to the osteotomy. Fibroadipose tissue is dissected medial to the hamulus to identify the white fibers of the tensor tendon. These are in close proximity to the nasopharyngeal muscosa and tendonolysis is best approached from the dorsal (nasopharyngeal) surface. With sharp or judicious electrocautery dissectionthe tensor tendon is identified and cut.