Abstract
Sleep Disordered Breathing (SDB) are characterized by nocturnal respiratory instability during sleep, and obesity is thought to be the most important factor for this disease. We paid special attention to the adipose tissue around the tongue and pharynx as a possible cause of the narrowing of the upper respiratory tract. There have been few previous reports comparing the fat in the pharynx to the increase of abdominal fat. In this study, to investigate the pathogenesis of SDB, we examined the relationship between the patterns of fat deposition in the abdomen and pharynx. On plane CT of 20 patients with SDB and 10 control patients, the pattern of fat deposition was estimated at the level of pharynx and abdomen. In the cases with SDB, the visceral fat was predominant, even in patients with a low Body Mass Index (BMI), compared to the predominant subcutaneous fat in control cases. These findings indicate that the pattern of abdominal fat deposition in SDB differs from that in control cases. In SDB patients, the rate of pharyngeal fat decreased as the BMI increased. In contrast, in control cases, the rate of pharyngeal fat tended to increase as the BMI increased. These findings also indicate that there is a discrepancy in the pattern of pharyngeal fat deposition between patients with SDB and the controls. As the rate of pharyngeal fat deposition was decreased in SDB, despite the increase of the apnea hypopnea index, other factors, such as the fat in the tongue or the base of the tongue, might also play an important role in patients with sleep breathing disorders.
