SURGERY FOR SNORING AND MILD OBSTRUCTIVE SLEEP APNOEA INTRODUCTION Snoring with or without excessive daytime somnolence, restless sleep and periods of apnoea are all manifestations of sleep disordered breathing. The last 30 years a greater understanding of the physiology and potential general health and societal consequences has led to some successes in both nonsurgical and surgical management of these problems. Numerous sleep disorders are categorised in the International Classification of Sleep Disorders by the American Sleep Disorders Association. The primary disorders that may warrant surgical intervention are snoring and mild obstructive sleep apnoea. PROBLEM Snoring is an undesirable sound that originates from the soft tissue of the upper airway during sleep. It is usually an issue of contention for the patients and their bed or dwelling partners and it may be a harbourer of something more serious, such as obstructive sleep apnoea. Obstructive Sleep Apnoea is a sleep disorder in which airflow is repeatedly reduced or stops. The disorder may vary in severity and is often associated with other physiological problems. These problems include altered mood and behavior (depression, lethargy, cognitive and memory impairment), morning headaches, decreased libido, systemic and pulmonary hypertension, congestive heart failure and sleep related arrhythmias among many others. Apnoea is obstructive only when Polysomnography reveals a continued inspiratory effort evidenced by abdominal and thoracic muscle contraction. In central apnoea, absence of airflow accompanies a lack of inspiratory effort and this condition is obviously not amenable to surgical correction. At times, apnoea may be mixed and these are the patients that represent the greatest therapeutic challenge to upper airway surgeons. The exact prevalence of obstructive sleep apnoea is unknown but most experts agree it is frequently under diagnosed. A large study of patients has shown that 28 % of women and 50 % of men aged between 30 and 60 are habitual snorers. When investigated with Polysomnography, 10 % of women and 33 % of men have a respiratory distress index of 10 or higher suggesting mild obstructive sleep apnoea. Obstructive Sleep Apnoea or OSA can occur at any age but is more commonly diagnosed in patients aged between 35 and 65 years. Sex; in adults, the male to female ratio is approximately 2 to 1. Aetiology; snoring is the result of incomplete pharyngeal obstruction. Turbulent airflow and subsequent progressing vibratory trauma to the
soft tissues of the upper airway are important factors that contribute to this condition. Anatomic obstruction at any level leads to increased negative inspiratory pressure which causes further airway collapse, more turbulence and more noise. The imbalance between pharyngeal tone and the negative inspiratory forces caused by the diaphragm and intercostal muscles is thought to be the primary aetiology of anatomical obstruction in obstructive sleep apnoea. Significant factors that contribute to this condition include obesity, redundant tissue in the neck retrognathia and craniofacial anomalies. In addition, anatomic abnormalities of the nasal airway (eg; septal deviation, inferior turbinate hypertrophy, nasal valve collapse or adenoid hypertrophy) play a significant role. Alcohol and other sedatives increase the severity of obstructive sleep apnoea. A useful source for obtaining the history for a patient who snores is the patient s bed partner. Typical symptoms include snoring, apnoeic episodes witnessed by a bed partner, excessive daytime somnolence and difficulty with memory and cognition. Other indications may indicate enuresis or bedwetting. Patients who are referred for surgical evaluation often report failed treatment with continuous positive airway pressure or CPAP. Treatment with CPAP usually fails because the patient cannot tolerate or dislikes the cumbersome CPAP facial appliance. DIAGRAM 1 Although most publications by Respiratory Physicians reported up to a 95 % initial success rate, actual compliance for adequate use over years is under 10 %. Adequate use is defined as at least 7 hours for more than 70 % of days. PHYSICAL EXAMINATION There are several structural predictive factors for obstructive sleep apnoea. Most patients with sleep apnoea are overweight and have short thick necks. Increasing neck circumference is lineally related to the probability of obstructive sleep apnoea and is in fact more specific than body mass index (BMI) in the clinical diagnosis of OSA. Maxillary and mandibular deficiency is an important finding. Examination of the nose often reveals an anterior nasal septal deformity and significant swelling of the inferior turbinates with poor mucosal reversibility after topical sympathomimetic amines. Examination of the oropharynx often reveals an elongated uvula, a small oropharyngeal opening and a large tongue. The uvula may telescope upon itself when the patient is asked to say aaaahhhh indicating an increased possibility that obstructive sleep apnoea is present. A recent study demonstrated a 70 % positive predictive index of tongue scalloping being associated with obstructive sleep apnoea. Scalloping of the
tongue is defined as multiple lateral glossal indentations that result from molar compression. Occasionally large tonsils are seen in adults, but this is more common in the paediatric age group. From the point of view of the Ear, Nose and Throat Surgeon, complete examination of the nose, nasopharynx, oral cavity, oropharynx, hypopharynx, larynx and neck are mandatory. The patient is asked to perform Mueller s manoeuvre. In this the patient enhales with their nasal passages occluded and their lips closed while the airway is examined with a Flexible Fiberoptic Laryngoscope. Ascertaining the level of greatest obstruction is often helpful in selecting candidates for surgery and in advising what operation may be most effective. In surgical candidates, the role of Video Sleep Nasendoscopy (VSN) is controversial. Artificially inducing sleep and relaxation while watching collapse of the airway directly via a Nasopharyngoscope is useful in trying to ascertain the degree of collapse, the narrowest upper airway segment but as to whether it is more effective than Mueller s manoeuvre is controversial. INDICATIONS FOR SURGERY Surgical management is indicated for snoring and cases of mild obstructive sleep apnoea where a surgical correctable abnormality is believed to be the source of the problem and the patient has tried continuous positive airway pressure without success. Relevant Anatomy; Surgical alteration of the upper airway usually involves 1 or more structures including the nasal septal, inferior nasal turbinates, adenoids, tonsils, anterior and posterior tonsillar pillars, uvula, soft palate or the base of the tongue. It is important to remember that in unusual cases, obstruction may occur at or above the level of the larynx. Contraindications; Palatal surgery is contraindicated in patients with submucosal cleft palates. Medical conditions that preclude the use of a general anaesthetic are also a contraindication to surgery. Imaging studies are rarely performed as their usefulness is not established, be they cephalometric radiography, CT scanning or MRI. Diagnostic Procedures; Polysomnography is the criterion standard for diagnosing sleep apnoea. Usually several parameters are measured; apnoea index the number of apnoeic episodes per hour (apnoea is defined as the absence of airflow at the nose and mouth that lasts for 10 seconds or longer during sleep. Respiratory disturbance index (RDI) is also known as the Apnoea Hypopnea Index (AHI) and is defined as the combined number of apnoeic and hypopnoeic episodes per hour. The severity of obstructive sleep apnoea is arbitrarily defined and differs widely from centre to centre. Recent recommendations for cut off levels based on RDIs are as follows:
Mild obstructive sleep apnoea 5 to 15 episodes per hour Moderate obstructive sleep apnoea 15 30 episodes per hour Severe obstructive sleep apnoea more than 30 episodes per hour Home Polysomnography is frequently performed in the United States and is starting to be performed more widely in Australia. Nocturnal oximetry where the patient s oxygen saturation is measured overnight is considered to be a much less reliable diagnostic tool. NON-SURGICAL TREATMENT The main stay of non-surgical treatment for snoring and obstructive sleep apnoea is Continuous Positive Airway Pressure. CPAP is administered via a nasal mask, nasal prongs or a mask which covers the nose and mouth. The treatment requires that the patient complies with wearing a mask which is sometimes uncomfortable at night. Certain patient lifestyles make carrying a machine impractical regardless of the unit s compactness. Mandibular Advancement Devices alter the position of the tongue and mandible in an attempt to relieve retrolingual upper airway obstruction. Recent studies have shown that they are as effective as CPAP in mild to moderate obstructive sleep apnoea. Long term use has been associated with temporomandibular joint problems. Behavioural treatment has been overlooked and understated. The association between obesity and obstructive sleep apnoea is very strong. Managed exercise and weight loss programmes have repeatedly shown to be as successful as medical or surgical intervention in the long-term management of obstructive sleep apnoea. Several centres are now recommending Bariatric Surgery as the most effective management option in individuals with significantly elevated BMI and moderate to severe obstructive sleep apnoea. SURGICAL OPTIONS When surgical therapy is indicated, conservative procedures are attempted first. Uvulectomy; A patient with a large uvula who snores and has few or no symptoms for apnoea is a candidate for Uvulectomy. This can be done chemically (Injection Snoroplasty) or mechanically. Mechanical Uvulectomy is usually associated with a light general anaesthesia and the uvula may be excised using Cold Steel, Electrocautery, Radiofrequency, Carbon Dioxide or Diode Laser. Pillar System; The pillar procedure or palatal implants is a relatively new, minimally invasive modality used to treat people with habitual snoring and those with mild obstructive sleep apnoea. The pillar procedure addresses the soft palate which is one of the main anatomical components of sleep apnoea in snoring. It is effective only if the soft palate is the predominant cause of
upper airway turbulence. Three tiny woven inserts are placed into the soft palate to stiffen and help reduce the vibrations that cause airway turbulence and snoring. Nasal Reconstruction; Relief of nasal obstruction alone may significantly improve snoring but rarely cures it. Normal nasal anatomy makes CPAP easier to comply with. A variety of surgical procedures including Nasal Septal Reconstruction, Turbinate Reduction and Nasal Valve Reconstruction are recommended for specific intranasal problems causing upper airway obstruction. Palatal Surgery; UPPP is the most common procedure for the treatment of snoring and obstructive sleep apnoea. This procedure was introduced by Fugita in 1981. Essentially it consists of a Tonsillectomy, reorientation of the anterior and posterior tonsillar pillars and excision of the uvula and a rim of soft palate. The procedure is painful and patients often spend 1 or 2 days in hospital for patient controlled analgesia (PCA). The results for snoring are excellent provided that the pharyngeal segment is the one predominantly causing turbulent airflow. The results for obstructive sleep apnoea are not proven. DIAGRAM 2 Genioglossal Advancement; This procedure involves performing a Mandibular Oteotomy with anterior repositioning of the genioglossis. Although it is theoretically attractive, its clinical efficacy is unproven. Maxillary/Mandibular Advancement; This involves major Orthagnathic Surgery to maintain occlusion and improve the retrolingual airway. Its efficacy in the treatment of moderate to severe obstructive sleep apnoea is proven. Tongue Base Surgery; Lingual Tonsillectomy, Lingualplasty, Laser Midline Glossectomy, Midline Tongue Reduction using coblation or radiofrequency ablation all attempt to reduce the mass of the tongue base. These operations can be associated with significant perioperative swelling or bleeding. Occasionally, nasopharyngeal or nasolaryngeal intubation or even temporary tracheotomy may be required. In cases where tongue base mass or retrolingual narrowing of the airway is the major problem these procedures, expertly performed, have proven clinical efficacy. OUTCOME AND PROGNOSIS Most investigators define successful treatment as a decrease of 50 % or more in the Respiratory Distress Index and a decrease in the number of episodes to less than 20 on Polysomnography. The best surgical success rates for multilevel surgical treatment of snoring and obstructive sleep apnoea report success, according to the above criteria in about 66 % of cases. For unilevel obstruction, there are published success rates of 90 % or more for Uvulopharyngopalatoplasty and Maxillary Mandibular Advancement Surgery.
It is important to note that patients who are no more than 25 % above their ideal body weight are likely to have short, medium and long term benefits from surgical treatment of snoring and mild obstructive sleep apnoea. Patients who are more than 25 % above of their ideal body weight have a linear decrease in success rate when compared to their BMI or body weight. FUTURE AND CONTROVERSIES Surgical treatment of snoring is well established. Controversy exists in the management of mild to moderate obstructive sleep apnoea. Bearing in mind that long-term compliance with nasal CPAP is low, a large subset of patients are appropriate candidates for surgery. Many procedures are available but with multilevel airway obstruction, the best long-term surgical results are still only around 60 % success rate.