Cephalometric analysis of permanently snoring patientswith and withoutobstructivesleep apnea syndrome
L a r s A n d e r s s o n 1, Viveca Brattstr6m 2 Departments of ~Oral & Maxillofacial Surgery, Central Hospital, V&sterfis and 2Orthodontics, Karolinska Institutet, Stockholm, Sweden
L. Andersson, V. Brattstrrm: Cephalometric analysis o f permanently snoring patients with and without obstructive sleep apnea syndrome. Int. J. Oral Maxillofac. Surg. 1991; 20: 159-162. Abstract. Habitual heavy snoring may be considered a preliminary stage of sleep apnea syndrome. This investigation deals with the craniofacial morphology of 51 heavily snoring patients, with and without obstructive sleep apnea, and with 28 healthy control patients. The apnea group showed a reduced posterior airway and a posterior rotation of the mandible. Reduction of the anterior-posterior diameter of the cranial base, maxilla and mandible and vertical reduction of the posterior facial height appeared to be c o m m o n facial characteristics in both snoring and apnea patients. These findings indicate an anatomical disposition for snoring and apnea.
In recent years increasing interest has developed in sleep-related breathing disturbances. Habitual snoring during sleep is seen in about 10% of the population, being more c o m m o n in men than in w o m e n 7. Habitual heavy snoring during sleep has been reported in 15.5 % o f the male population 6. A correlation to overweight has been reported 6. Habitual heavy snoring may be considered a preliminary stage of the sleep apnea syndrome with periodic cessation of breathing 18'19. Sleep apnea can be divided into 2 categories, central and obstructive. Central apnea is associated with total cessation o f diaphragmatic activity, while the more c o m m o n obstructive sleep apnea is secondary to obstruction of the upper airway and does not include decreased muscle activity o f the diaphragm 8. The obstructive sleep apnea syndrome (OSAS) is associated with a number of conditions, such as headache, nightmares, dry throat, excessive daytime sleepiness, deterioration of memory a n d judgement, anxiety and depression s. Physiologic changes, such as hypertension and oxygen desaturation are c o m m o n 6"24. Cardiac arrythmias and even cardiac arrest, with resulting death during sleep, have been reported 13'14. A number of anatomic malfor-
mations have been reported in OSAS patients, such as mandibular deficiency2,25, elongated soft palate 3,1s,17,2l, enlarged tongue 3'15'~7'21, decreased posterior airway space 15,21, and inferior position of the hyoid bone 3,15,21. Habitual snoring may occur in patients with or without OSAS. It was therefore considered of interest to investigate whether snoring patients had anatomical characteristics similar to those reported in OSAS patients. The purpose of the present study was to examine the craniofacial morphology o f heavily snoring patients, with and without OSAS and to compare those with non-snoring controls.
Material and methods
The patients selected were permanent snorers admitted for OSAS screening at the Central Hospital, V/isterfis. Controlled registration of apneas and oxygen saturation during sleep w e r e performed. In addition, an ENT examination was done, including nasopharyngoscopy. Height and weight were recorded and lateral skull radiographs taken. Since most patients were males, females were not included in the present study. Two edentulous patients were excluded from the cephalometric analysis. The material w a s divided into 3 groups;
Key words: cephalometry; craniofacial morphology; sleep apnea; snoring. Accepted for publication 6 February 1991
The apnea group (n = 23) comprising habitual snorers with frequent apneas during sleep and oxygen desaturation of < 90%. The snoring group (n = 28) comprising habitual snorers with or without occasional apneas but with an oxygen saturation of > 90%. The controlgroup (n = 28) comprising mate dentists w h o w e r e not habitual snorers. The size and mean age of each group are shown in Table 1. On the lateral skull radiographs 30 landmarks were digitized twice and the mean coordinates for each landmark stored in a computer. The reference points are shown in Fig. 1. Frequently used landmarks are considered well known to the reader, however some uncommon landmarks are defined in Table 2. Linear and angular variables were recorded and possible differences between the group means tested by Student's t-test. The cephalometric analysis contained 42 variables. The error of the method included double determination of all cephalometric landmarks. The method error was calculated using the formula: s(i) =
Table 1. Patient distribution Number Age
Andersson and B r a t t s t r 6 m
NSL 0 '
Fig. 2. Mean facial diagrams of the apnea
( - - ) , snoring (---) and control (....) groups, orientated on a horizontal sella-nasion line.
Fig. 1. Anatomical landmarks on lateral skull radiographs. Landmarks which are not so
commonly used are defined in Table 2.
Table 2. Definition of some uncommon cephalometric points used in the study
Point Definition aa ba e h mlp pawl
The most anterior point on the atlas vertebrae Basion. The most posterior inferior point on the clivus. The tip of the soft palate. Hyoid. The most anterior superior point on the body of the hyoid bone The posterior tangent point of the mandibtflar plane, ML Posterior pharyngeal wall 1. Point on the posterior pharyngeal wall identified by the extension of the maxillary plane (NL) ans-pm paw2 Posterior pharyngeal wall 3. Point on the posterior pharyngeal wall identified by the extension of the occlusal line midpoint of the incisor tips and the occlusal surface of the first mandibular molar. paw3 Posterior pharyngeal wall 3. Point on the posterior pharyngeal wall identified by the extension of the line sm to go ph The perpendicular from h to the mandibular plane ML t Tongue. Point on the tongue intersecting the extension of the occlusal line tb Base of the tongue. Point on the tongue intersecting the extension of the line sm to go
Table 3. Distribution of height and weight
Apnea n = 23 Height (cm) Weight (kg)
Sjaorers n = 28
where d is the difference between two measurements and N is the number of double determinations. The method of error varied between + 3.2 (Ils/Ili) and + 0.2 (SNB). It was found with one exception (Ils/Ili = 5.8) that the error of variance (s?) was < 3% of the biological variance (s2).
Controls n = 28