1

Introduction

Obstructive sleep apnea (OSA) is a common sleep disorder. It is characterized by repetitive apneas and hypopneas during sleep. These events are due to partial or complete collapse of the upper airway, resulting in decreased oxygenation and sympathetic overdrive. Frequent arousals occur, causing sleep fragmentation, which leads to excessive daytime sleepiness, morning headaches, poor concentration, memory loss, frustration, depression, and even marital discord. The mechanism of upper airway collapse in OSA is usually multifactorial. Many authors concur that most patients with moderate and severe OSA are likely to have multilevel obstruction involving the palate, the lateral pharyngeal walls, and/or the base of tongue. Nasoendoscopic examination of the patient’s anatomy is crucial. Inspection is performed of the nasal passage, the sinus turbinates, the nasal septum, and the presence of adenoids; the retropalatal space is important; and the lateral pharyngeal walls may be thick and/or bulky; the retroglossal space may be narrow as well. Mueller maneuver may still be used and grades airway collapse at three levels, namely the velopharynx, lateral pharyngeal wall, and the base of tongue. There are surgical procedures that can address these various anatomic sites of collapse in these patients. The lateral pharyngeal wall collapse can also be dealt with by creating tension in the lateral walls by the lateral pharyngoplasty or the expansion sphincter pharyngoplasty. Other pharyngeal palatoplasty techniques include the traditional uvulopalatopharyngoplasty (UPPP), the Z-plasty, or the transpalatal advancement pharyngoplasty; tongue base procedures also include a midline glossectomy, hyoid suspension, lingual tonsillectomy, genioglossus advancement, tongue suspension sling suture, robotic tongue base surgery, and the hypoglossal nerve stimulation.

The site of obstruction is less important when the modality of therapy is a tracheostomy or nasal continuous positive airway pressure (CPAP), which indiscriminately overcomes all collapsible airway segments much like a “pneumatic splint.” When upper airway surgery is contemplated, it is critical to tailor the approach according to the site of obstruction noted preoperatively, and for this drug-induced sleep endoscopy (DISE) may be used in certain circumstances. The type of surgery employed would depend on the site of anatomic collapse, whether the palatal, lateral wall, and/or tongue base collapse.

A staged approach to the upper airway reconstruction is acceptable, and even endorsed by the American Sleep Disorders Association. When multilevel obstruction is present, the chances of surgical success may be improved by addressing multiple anatomic sites at a single surgical sitting.

The initial staged approach was described by Fujita, when he introduced the UPPP for OSA. He recognized that the upper airway may collapse at multiple levels; hence he also described the laser midline glossectomy for patients who failed UPPP and who were diagnosed as having retrolingual obstruction. It was Riley et al. who first advocated simultaneous multilevel pharyngeal surgery for patients with multilevel obstruction. They showed promising success with minimal complications. Many authors have reported minimal complications with one-stage multilevel pharyngeal surgery (including nasal surgery, if required) for patients with OSA.

2

Surgical Planning (Pang–Woodson Surgical Protocol)

Based on basic physics and the pathophysiologic basis of airflow dynamics, the proper assessment of the nasal cavity and passage is of essence. In addition, the upper airway in the nose itself represents over 70% of the entire airway tract resistance, from the nasal cavity to the minute alveoli.

During inspiration, negative pressure is created within the intrapleural space (e.g. −8 cm H ₂ O) to distend the alveoli and to suck in or inhale air from the atmosphere into the lungs for gaseous exchange and oxygenation of the blood. This act of inhalation exerts a negative pressure on the entire upper airway, including the hypopharyngeal, retroglossal, and retropalatal space. Hypothetically, if there were any form of upper airway blockage within the nasal passage (e.g. a deviated nasal septum, enlarged swollen turbinates, nasal polyps, etc.), the lungs would have to work “harder” to create a “more negative pressure” (e.g. −30 cm H ₂ O) to inhale air from the atmosphere; this would ultimately result in a greater negative pressure on the hypopharyngeal, retroglossal, and retropalatal space, potentially leading to collapse and obstruction of the hypopharyngeal upper airway. It is also important to understand that without any form of obstruction in the nose, the airflow into the lungs through the nose would be laminar; however, with nasal blockage, there would be turbulent airflow within the nasal cavity and passage, resulting in higher nasal resistance, poorer nasal breathing, and snoring with vibration of the palate (the first site of contact from the turbulent airflow). Therefore although surgical correction of anatomic obstruction of the nasal passage alone does not cure obstructive sleep apnea, it may still significantly decrease the negative pressure within the pharynx.

3

Patient Selection

The key to surgical success is patient selection. Patients with OSA must be treated in a holistic manner, as many of these patients are overweight or obese and have associated comorbidities like hypertension, ischemic heart disease, and/or cerebrovascular disease. The overweight patient should be put on a strict weight loss and dietary regimen while being on nasal CPAP until the ideal body weight is attained. Bariatric surgery should also be considered part of the surgical armamentarium in the management of these obese patients with OSA. Nasal CPAP has always been an option for patients in the treatment of OSA. It is undoubted that the nasal CPAP is effective for the OSA patient if used properly. However, it is also universally known that patient compliance is a major problem in the use of nasal CPAP.

Surgical techniques for the treatment of OSA have been long frequently criticized and frowned upon, especially the UPPP. The UPPP was the most common surgical procedure performed for sleep-disordered breathing (SDB). Traditionally, UPPP was used mainly for patients with collapse/obstruction of the soft palate during the Muller maneuver. The Muller maneuver was first described by Borowiecki and Sassin for the preoperative assessment of OSA. According to Fujita’s three types of collapse of the upper airway during sleep, Muller maneuver was able to identify Fujita type I (soft palatal) collapse and hence isolate patients suitable for UPPP. This, unfortunately, was not always the case, as multiple factors are involved in the dynamics of OSA, and many patients have multilevel obstructions. Due to the varied clinical indications for this procedure, many authors have found unfavorable postoperative results.

Sher et al. reviewed a meta-analysis of reported UPPP procedures and found an overall success rate of only 40%. In an attempt to improve surgical success rates, Friedman et al. devised a clinical staging system for SDB to better select patients for the UPPP. They described stages based on Friedman tongue position, tonsil size, and body mass index (BMI):

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  Stage I: Friedman tongue position I and II: Tonsil size 3 and 4, BMI <40

  
  
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  Stage II: Friedman tongue position I, II, III, and IV: Tonsil size 1, 2, 3, and 4, BMI <40

  
  
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  Stage III: Friedman tongue position III and IV: Tonsil size 1 and 2, any BMI

Friedman reported an overall success rate of 80.6% for stage I, 37.9% for stage II, and 8.1% for stage III. It is well accepted that patients with Friedman tongue position III and IV are indicative of a large tongue, suggesting that if surgery is contemplated, some form of tongue base surgery would be appropriate as well. Most authors concur that patients who are noted to have multilevel collapse with the Muller maneuver on endoscopy of both the palate and tongue base should have both levels addressed at the same surgical sitting. Friedman et al. showed that selected patients with stage II and stage III disease treated with UPPP and tongue base reduction using a radiofrequency technique had remarkably improved results. Follow-up at 6 months showed successful treatment of patients with stage II disease, with success rate improving from 37.9% to 74.0% and stage III disease improving from 8.1% to 43.3%.

Severity of OSA has also been noted to correlate with clinical examination, namely Muller maneuver. It was demonstrated in 102 patients that OSA severity strongly correlated with Mallampati grade (r = 0.389, P < 0.0001), Friedman clinical staging (r = 0.331, P = 0.0007), and Muller grades of collapsibility at all three levels. Of significance, only 6.9% of patients with mild OSA had a >50% collapse of the base of the tongue region compared with 65.9% of patients with severe OSA. This illustrates that patients with severe OSA are 10 times more likely to have tongue base collapse than patients with mild OSA. Hence, patients with severe OSA and with tongue base collapse noted on Muller maneuver, falling into Friedman stage II or III, should have multilevel surgery to achieve the best possible results. Currently, DISE, discussed in another chapter in this book, has been shown to aid the sleep specialist in identifying the anatomic site of obstruction and perhaps aid in increasing the success rates.

It is pertinent to note that nasal surgery is also considered when the patient has significant nasal obstruction that has failed medical therapy (topical nasal steroids) and especially when the patient would want correction of the nasal obstruction independent of its effect on their sleep. However, it is reported that nasal surgery alone has only a 15.8% success rate as a treatment of OSA. The caveat would be the safety of multilevel surgery addressing all three levels—the nose, palate, and tongue base—at the same surgical sitting. Many authors concur that there is no evidence of increased complication rate or morbidity with these procedures performed together.

Note: Only some procedures are covered in this chapter, as other procedures are covered in other chapters in this book.