Chapter 36 Transpalatal advancement pharyngoplasty
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.
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.
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.
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.
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