Computed Tomography and Cephalometric Evaluation of Obstructive Sleep Apnea Syndrome

To examine the changes of upper airway cross sectional area in each phase of respiration in different degrees of severity of OSAS with computed tomography and cephalometry to decide on further treatment. A Prospective study was done in the Department of Radiology and Imaging, Kasturba Medical College, Mangalore, spanning over a period from March 2017 to December 2019. 50 patients were included in the study including control group. Patients who had at least 2-3 major symptoms of sleep apnea such as snoring, daytime somnolence, and apnea were included in this study. All patients were examined and then subjected to polysomnography(PSG) and upper airway CT. Patients with apnea-hypopnea index (AHI) of < 5 on Polysomnography were included in the control group and those with AHI of > 5 were categorized in to the study group Cross-sectional area of the airway at the level of the nasopharynx, oropharynx and the hypopharynx were obtained. Standard cephalometric measurements were made on a lateral radiograph of skull/ CT scanogram. Of the 36 patients in the study group, 31 patients were males and 5 were females. In the control group of 12 patients, 8 were males and 4 females. The cross sectional area at the lower border of the nasopharynx which is also the level of the nasopharyngeal sphincter was the most affected level in OSAS (p value of < 0.0001). Mean uvular diameter in the control group was 9.6 mm and in the OSAS group it was 11.2 mm. The mean length of the soft palate was 36.4 mm in the controls, 39.5 mm in the mild/moderate OSAS and 41.2 mm in the severe OSAS group. Obstructive sleep apnea is a complex disorder characterized by apneic episodes during sleep. In this study the most common site of obstruction is nasopharyngeal sphincter and the oropharynx. Although PSG is the diagnostic test of choice, imaging plays an important role in planning surgical and conventional treatment.