You are in: eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > PALATAL AND MAXILLOFACIAL SURGERY Snoring and Obstructive Sleep Apnea, Upper Airway EvaluationArticle Last Updated: Apr 25, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 9
  Author: David Núñez-Fernández, MD, PhD, Assistant Professor of Otolaryngology (External Associate), Department of Otolaryngology-Head and Neck Surgery, Charles University Faculty of Medicine of Hradec Králové, Czech Republic David Núñez-Fernández is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, Mexican Academy of Cosmetic Surgery, Mexican Society of Otolaryngology, Head and Neck Surgery, and Mexican Society of Rhinology and Facial Surgery Coauthor(s): Miguel Ángel García-Osornio, PhD, Private Practice in Otorhinolaryngology; Jan Vokurka, MD, PhD, Head, Associate Professor, Department of Otolaryngology, Charles University Hospital of Hradec Králové, Czech Republic Editors: Jack A Coleman, MD, Consulting Staff, Franklin Surgical Associates; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Robert M Kellman, MD, Professor and Chair, Department of Otolaryngology and Communication Sciences, State University of New York, Upstate Medical University; Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders; Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine Author and Editor Disclosure Synonyms and related keywords: upper airway examination, upper airway evaluation, examination of the upper airway, OSA, obstructive sleep apnea syndrome, OSAS, obstructive sleep apnea, sleep disorders, snoring, upper airway obstruction, deviated septum, polyposis, septal hematoma, septal dislocation, rhinitis, turbinate hypertrophy, carcinoma, adenoidal hypertrophy, lymphoma, stenosis, pharyngeal flap, papillomatosis, hypertrophied tonsils, elongated palate, elongated uvula, thickened palate, thickened uvula, lymphoma of the tonsils, lingual cysts, lingual tonsillar hypertrophy, macroglossia, micrognathia, lipoma of the neck, Hunter syndrome, Hurler syndrome, papillomatosis, edema of the epiglottis, vocal cord paralysis, laryngomalacia, collapse of aryepiglottic folds, choanal atresia, epignathus INTRODUCTIONSection 2 of 9
  For patients in whom obstructive sleep apnea (OSA) is suspected or is diagnosed, examination of the upper airway is essential for determining an optimal treatment. Many variables are involved in the pathogenesis of the disease, making the choice of the correct treatment a complex one. For excellent patient education resources, visit eMedicine's Ear, Nose, and Throat Center and Sleep Disorders Center. Also, see eMedicine's patient education articles Snoring, Sleep Disorders in Women, and Sleep Disorders and Aging. RELEVANT ANATOMYSection 3 of 9
The upper airway begins at the entrance of the nose and continues to the hypopharynx. Each part of this tract can cause obstruction, and sometimes, obstruction is found in several areas in varying degrees. The structures forming the upper airway are the nose and the pharynx with its 3 divisions (ie, nasopharynx, oropharynx, hypopharynx). Each of these areas has different pathologies that can produce stenosis of the airway. Structures of special concern Nose: The internal nasal valve, the septum, and the choana are areas of special concern. Nasopharynx: This area is particularly important in children because the adenoids are commonly hypertrophied, producing obstruction. Hypertrophied adenoids are the most common cause of obstructive sleep apnea (OSA) in children. Oropharynx: The soft palate, tonsils, palatoglossal and palatopharyngeal arches, and the tongue are structures of concern. In addition, the cross-sectional diameter of the pharynx can be smaller in many patients, playing an important role in the pathogenesis of OSA. Hypopharynx: The base of the tongue is the most influential structure in this area. PATHOLOGIC CONDITIONS ASSOCIATED WITH OBSTRUCTIVE SLEEP APNEA SYNDROMESection 4 of 9
Nose Deviated septum Polyposis Septal hematoma Septal dislocation Rhinitis Turbinate hypertrophy Nasopharynx Adenoidal hypertrophy Lymphoma Stenosis Pharyngeal flap Papillomatosis Mouth and oropharynx Hypertrophied tonsils Elongated and/or thickened palate and uvula Lymphoma of tonsils1 Lingual cyst Lingual tonsillar hypertrophy Macroglossia - Acromegaly Micrognathia - Congenital or acquired Lipoma of the neck Hunter syndrome Hurler syndrome Head and neck burns Papillomatosis Larynx Edema of epiglottis Vocal cord paralysis Laryngomalacia2 Collapse of aryepiglottic folds PEDIATRIC ABNORMALITIES CAUSING AIRWAY OBSTRUCTIONSection 5 of 9
Nose Choanal atresia Polyposis Dermoid cyst Tumors - Gliomas, teratomas, fibrous histiocytomas, encephaloceles Nasopharynx Adenoidal hypertrophy Stenosis Pharyngeal flap for cleft palate Tumors Mouth and oropharynx Hypertrophied tonsils Macroglossia due to lingual hemangioma Macroglossia due to lingual lymphangioma Micrognathia Epignathus Temporomandibular joint ankylosis Larynx Tracheal atresia Intrinsic tracheal lesions Extrinsic compression (goiter) Laryngeal and tracheal webs Kimura disease3 Other pathologies Charcot-Marie-Tooth disease4 PHYSICAL EXAMINATIONSection 6 of 9
A systematic approach to physical examination is recommended to avoid confusion. General AppearanceMany adult patients with obstructive sleep apnea syndrome (OSAS) are overweight or obese. Pickwick syndrome in patients with obesity is associated with hypersomnolence and sleep apnea. Patients with a wide and short neck are prone to develop OSA. Many patients with obesity have a narrow pharynx. Waist and neck circumferences have a strong correlation with the severity of sleep apnea. However, children with OSA are not necessarily obese; rather, they are lacking in development and are generally underweight. Elevated levels of interleukin 6 (IL-6), tumor necrosis factor-a (TNF-a), and insulin have been found in patients with excessive daytime sleepiness (EDS). Vgontzas et al (2005) proposed that these cytokines were mediators of daytime sleepiness. Visceral fat was found to be a primary parameter linked to OSAS. Facial and Cervical CharacteristicsAnatomic characteristics commonly associated with OSAS include micrognathia, retrognathia, a short and thick neck, and abnormal positioning of the hyoid. Chronic nasal obstruction generally produces a long face. Certain craniofacial relationships have a greater potential to produce apnea than others. In 1990, Lowe reported that a high apnea index was found in patients who had a large volume of the tongue and soft palate, obesity, a retrognathic mandible, an open-bite tendency between the incisors, and an anteroposterior discrepancy between the maxilla and mandible.5 Nasal ExaminationNose and nasal cavity Obstruction of the nasal passage can begin at the entrance. Rhinoscopy can reveal nasal septum deviations and problems at the valvular area. The area of highest resistance in the nose is the nasal valve; therefore, a small deviation in that area can produce a higher degree of obstruction than a larger deviation in any other part of the nose. External nasal valve collapse can be produced by weakening of the alar rim or by an extremely wide columella. The internal nasal valve is a common source of obstruction. A small deflection of the nasal septum in this area produces more obstruction than in any other part of the nose. Deviations of the nasal septum can produce obstruction of the nasal passage. When the deviation is big enough, the contralateral inferior turbinate develops hypertrophy to compensate for the excessive widening of the nasal fossa. This hypertrophic turbinate sometimes produces obstruction by itself. Allergic rhinitis or sinusitis may cause rhinorrhea. Rhinitis, caused by allergies or some other etiology, can produce constant obstruction of the nose. This problem is frequently aggravated at night when the patient is lying in bed because of the redistribution of fluids in the body. Nasal polyposis can be particularly troublesome. Many craniofacial syndromes cause midfacial hypoplasia that produces nasal obstruction. In many cases, visualizing the rhinopharynx is possible, although applying a topical vasoconstrictor beforehand is sometimes necessary. Less common pathologies, such as choanal stenosis or atresia, can produce obstruction of the airway.6 Nasopharynx The nasopharynx can be better examined with a rigid or flexible endoscope because the nasopharynx is located at the bottom of the nasal cavity. The most common problem in this area is adenoid hypertrophy. Adenoid hypertrophy is normal in children aged 6 months to 5-6 years. Absence of hypertrophy is abnormal at this age. Adenoid hypertrophy can be large enough to produce nasal obstruction. Adenoid hypertrophy in adults is uncommon; however, several studies report this pathology in patients as old as 52 years. This author has found adenoid hypertrophy confirmed by histopathologic examination in patients as old as 63 years. Tumors are an uncommon finding. Oral and oropharyngeal examinationDental anomalies, such as open-bite deformity or micrognathia class II occlusion, are easy to detect. A high arched palate is common in patients with chronic nasal obstruction. Gum size is important because hypertrophic gums are generally associated with chronic oral respiration. Palate The velum of the palate is particularly important for the pathology of airway obstruction. A long velum or a flaccid velum can produce obstruction. The soft palate frequently is elongated, increasing the possibility of snoring. Many patients have pharyngeal and palatal edema after sleep because of the snoring-induced trauma. Upon examination, the patient is asked to open the mouth and extend the tongue to assess the length of the soft palate. The Mallampati classification is used to describe the size of the palate and its relationship to the rest of the pharyngeal structures. This classification helps to predict the difficulty of orotracheal intubation. The uvula generally is larger than that of the normal population. This is due to edema and thickening of the covering epithelium. The uvula of snorers and OSA patients contains less muscle than that of nonsnorers and can sometimes produce obstruction because of the edema. Macroglossia, an enlarged tongue, can be found in many patients with obesity and is commonly found in patients with Down syndrome. The tongue can be so large that it produces airway obstruction and has to be reduced with surgery. The base of the tongue is more commonly involved in the pathogenesis of obstruction. No direct correlation between tongue size and the apnea-hypopnea index (AHI) has been discovered. Oropharynx The overall width of the pharynx is particularly important. Reduction in the width of the pharynx because of obesity affects the hypopharynx. Drainage along the posterior wall of the pharynx is commonly correlated with adenoid hypertrophy. Tonsillar hypertrophy can produce airway obstruction (see Image 4). This pathology is more common in children but also has been described in adults. Tonsillar hypertrophy occurs most commonly in pedunculated tonsils that rotate towards the pharynx when the patient lies down. The tonsils do not have to be very large. A statistically significant correlation between tonsil size and respiratory disturbance index has been found.7 Perhaps the most important factor in OSA is the collapsibility of the pharynx. Most persons with OSA have a decreased tone of the pharyngeal muscles. This allows the pharynx to collapse even with small levels of intrapharyngeal negative pressure (see Müller maneuver). Micrognathia can be a life-threatening pathology in some patients, such as those who have Pierre-Robin syndrome. In certain circumstances, temporary glossopexy may need to be performed to avoid asphyxia until a secure airway is obtained. Hypopharynx Examination of the hypopharynx requires the use of a laryngeal mirror, flexible endoscope, or a magnifying laryngoscope. A gag reflex that is very intense is a common problem in some patients. The gag reflex can make performing the examination of the hypopharynx difficult or impossible. Flexible nasopharyngoscopy is the method of choice in these patients. The size of the hypopharynx can be decreased because of alterations at the base of the tongue. The diameter of the hypopharynx is decreased in patients with obesity. The tongue plays a major role in the pathogenesis of snoring and apnea. The lingual tonsils can be hypertrophied, and tumors may be present, such as those developed from a lingual thyroid. The epiglottis can prolapse during inspiration, producing airway obstruction. In 1998, Catalfumo reported this problem in 11.5% of patients in whom a uvulopalatopharyngoplasty (UPPP) was unsuccessful.8 These patients were treated with a partial epiglottidectomy with laser. Another factor is the degree of redundancy of the mucosa in the arytenoid-aryepiglottic fold area, which is correlated with an increase of the apnea index when the mucosa is markedly redundant.9 Other methods of examinationSuperior airway resistance measurement and manometry were developed to evaluate the difference in pressure in the areas with high possibility of collapse (ie, hypopharynx, oropharynx, the region of the velum of the palate). The relative pressures in these areas are compared with the pleural pressure measured through the esophagus. This test may be performed during polysomnography; however, this test is not commonly used because of its complexity. Anterior rhinomanometry has been found to have a high sensitivity (91%) and specificity (96%) to detect sleep apnea in children with adenotonsillar hypertrophy and a nasal resistance of 0.59 Pa/cm3/s.10 CommentaryMost of the above-mentioned characteristics are suggestive of sleep apnea; however, none is considered pathognomonic of the disease. Radiologic examination and polysomnography are necessary to complement the study and are of particular importance in choosing the best treatment for the patient. A 1999 study by Woodson found no correlation between Mallampati presentation and Müller maneuver and the AHI.11 The same study established a correlation between AHI and body mass index (P <0.0001), posterior wall redundancy (P = 0.0004), and endoscopic retropalatal size (P = 0.0046). However, the sensitivity (50-60%) and specificity (63-70%) of the clinical impression are low. In search of a decision rule for OSA, Tsai found that patients with a cricomental distance of 1.5 cm or less, a pharyngeal grade II, and overbite had a positive predictive value of 95% for OSA and a negative predictive value of 49%. A cricomental space of more than 1.5 cm excluded OSA.12 RADIOLOGIC EVALUATIONSection 7 of 9
Different imaging methods for the evaluation of patients with OSA have been tried. Radiologic evaluation should aid in making a correct diagnosis and in planning the appropriate treatment. This, however, is not always the case. The anatomy of the pharyngeal walls should be correctly evaluated using the various diagnostic tools available. The airway was previously evaluated using measurements of electromyographic activity during sleep and intrapharyngeal pressure. However, these methods did not accurately represent the behavior of the pharyngeal structures surrounding the airway. Currently, different methods are used to provide a better understanding of the airway. The methods currently used are acoustic reflection, fluoroscopy, cephalometry, and computed tomography and magnetic resonance imaging. The advantage of these methods is that they are not invasive, although some of them involve exposure to x-ray radiation. Nasopharyngoscopy provides an image of the upper airway, and dynamic tests can be performed. The only drawback is that nasopharyngoscopy is invasive, although the discomfort produced by the instrument has been reduced considerably with the new slimmer models. Flexible nasopharyngoscopyThis study is popular for OSA examination. It allows examination of the nose, all portions of the pharynx, and the larynx all in one procedure. When performing the nasopharyngoscopy, dynamic tests are possible. Beginning in the rhinopharynx, Passavant sphincter is evaluated during the closure of the velum of the palate. Afterwards, the patient is asked to perform Müller maneuver. This maneuver is useful to assess the collapsibility of the pharynx. The base of the tongue and the glossoepiglottic recesses are examined by asking the patient to extend his/her tongue. Evaluating the diameter of the pharynx and the characteristics of the epiglottis is also possible. The Müller maneuver is performed with the nasopharyngoscope in the pharynx. The patient is asked to breathe while the lips are closed and the physician closes the nasal valves with his/her fingers. In this way a negative pressure is created in the pharyngeal area and evaluating the retropalatal, retroglossal, and retroepiglottic spaces is possible.13
Disadvantages of nasopharyngoscopy
FluoroscopyFluoroscopy has the advantage of producing dynamic images with the patient seated or reclining, awake or sleeping. It is useful to evaluate the areas of obstruction in the supine position. However, it is not sensitive enough to measure changes in the cross sectional size of the airway. The drawbacks of the technique are that the patient has great exposure to x-ray irradiation and that performing sectional cuts of the area is not possible. This situation has made the technique impractical and has limited its use. CephalometryThis plain radiographic study is the most commonly used in OSA patients. Cephalometry is used to examine both the soft tissue and the osseous structures related to the airway. It is widely available, easy to perform, and has a low cost. One of the main advantages is that it is standardized. The exposure should be taken at the end of the expiration. The main utility of cephalometry is to evaluate craniofacial abnormalities (eg, retrognathia, micrognathia). The most common cephalometric findings in OSA patients are retrognathia, narrowing of the posterior airway space (PAS), elongation of the soft palate, increased volume of the base of the tongue, and a low position of the hyoid bone. A limitation of the study is that it produces a bidimensional representation of the airway, showing only the anteroposterior dimensions. It does not provide any information on lateral structures. Researchers have found a statistically significant correlation between an increase of the apnea index (AI), a PAS-epipharynx distance less than 7 mm, and an MP-H distance greater than 27.4 mm.9 Several authors have found that the narrowing of the airway in OSA patients takes place mainly in the latero-lateral direction. This limits the utility of the study, but it still has a place in the evaluation of the patient and especially in those patients in whom involvement of the mandible or maxilla is suspected to produce obstruction. Special notice should be given to adenoids. They can be evaluated more accurately in cephalometry because of the better alignment of the head. This avoids the distortion produced by rotation of the head, which can suggest a false hypertrophy of adenoids. Several classifications of adenoid hypertrophy exist. However, because of the variation of the pharyngeal size at different ages and the variation between different children, establishing a normal size of the retropalatal space is difficult. Viewing the tonsils in patients with tonsillar hypertrophy is also possible (see Image 6). Reference points used by several authors (Fujita, Riley, Chabolle, Soda-Merhy) See Image 5. S: This point is taken from the center of the sella turcica. N: Nasion is the most anterior point of the frontonasal suture. A: Subspinal point is the most depressed part of the superior incisive fossa. B: Supramental point is the most depressed part of the inferior incisive fossa. Gn: Gnathion is the most inferior point of the mandibular symphysis. Go: Gonion is the most posterior and inferior point of the angle of the mandible. H: Hyoid is the most anterior and superior point of the hyoid body MP: Mandibular plane is a plane joining gonion with gnathion. PSP: This is the posterior nasal spine. P: This is the most inferior and posterior point of the soft palate. Angles and spaces measured See Image 5. SNA angle measures the projection, anterior or posterior, of the maxilla. The reference range value is 82 ± 2°. SNB angle measures the position of the mandible. The reference range value is 80 ± 2°. Less than this is considered retrognathia. ANB angle measures the position of the maxilla with the mandible. The reference range value is 2°. This measures prognathism. MP-H is the distance between the mandibular plane (MP) and the hyoid bone (H). The reference range is 11-19 mm. The longer the distance, the higher the possibility of the patient having OSA. PSN-P is the length of the velum of the palate. The reference range value is 37 ± 3 mm. G is the width of the velum of the palate. The reference range is 6-10 mm PAS is the PAS or retroglossal space; the reference range is 10-16 mm Retropalatal space is the narrowest measurement between the posterior surface of the velum of the palate and the posterior pharyngeal wall. Computed tomography scanningCT scanning produces excellent resolution of images to evaluate both the soft tissue and the osseous structures of the pharynx-larynx complex. It has the advantage of producing axial and coronal cuts. Also, producing sagittal reconstructions is possible. Measurements can be taken with CT scanning. Volumetric reconstruction and 3-dimensional imaging is possible with the newer equipment (helical CT scanning). In CT studies, viewing the difference in shape of the pharynx between nonsnorers, snorers, and OSA patients is possible. CT scanning has been used by many authors studying the pathogenesis of OSA. The advantages of CT scanning are its wide availability and the quickness with which newer scanners can perform studies. Volumetric and 3-dimensional reconstructions of the airway and other peripharyngeal structures are possible. The study is performed in the supine position. Disadvantages of the study are that radiation is involved, limiting the number of studies that can be performed. CT scanning is also relatively expensive. The actual image is in the axial plane, so performing a reconstruction is necessary to obtain a sagittal image High-speed CT scanning (with electron beam) has been used for correlating the image with the different phases of snoring. Magnetic resonance imagingMRI is probably the best imaging study for OSA patients because of its excellent resolution in the supine position. It provides a detailed view of the fat and soft tissue of the pharyngeal walls and its relation with the airway. Obtaining sagittal, coronal, and axial images, as well as 3-dimensional reconstructions, is also possible. Measurements of the different structures and their volume are possible. It has the advantage of being radiation free, thus making performance of several studies possible. Although the noise and the cumbersome design of the machine makes sleeping in it difficult, MRI has been used during sleep to study the effects of continuous positive airway pressure (CPAP) therapy. In addition, performing dynamic studies is possible because of faster equipment. MRI is beginning to have a role in the evaluation of patients before and after surgeries such as uvulopalatopharyngoplasty, resection of tongue base, or geniohyoid muscle surgery. MRI is an expensive study, especially with the newer technologies, making its price the real limit to the number of studies that can be performed. MULTIMEDIASection 8 of 9
REFERENCESSection 9 of 9
Snoring and Obstructive Sleep Apnea, Upper Airway Evaluation excerpt Article Last Updated: Apr 25, 2008 | ||||||||||||||||||||||||||||||||||||||||||
