Abstract
Obstructive sleep apnea syndrome (OSAS) is a
group of disorders in which breathing stops intermittently
and repeatedly for 10 seconds or more
during sleep. The causal site of the disorders is
thought to be in the upper airway above the glottis.
In order to understand the three-dimensional features
of the oral and peripharyngeal structures
involved in the disorders, we calculated the
tongue volume/oral cavity volume ratio (TV/OCV
ratio) in the oral cavity using magnetic resonance
imaging (MRI) for both OSAS patients and normal
controls. The study subjects comprised 20 male
patients with OSAS (apnea—hypopnea index
[AHI] ≥5.0, with a diagnosis of OSAS) and 20 normal
male adults (AHI<5.0, with no history of
OSAS) as the controls. We performed MRI to
acquire T1- and T2-weighted images. We estimated
tongue volumes on the basis of the cross-sectional
area of each image, then using the tongue volume
data, we calculated TV/OCV ratios. In the normal
control group, mean (±SD) body mass index
(BMI) was 21.68±1.73 and the mean TV/OCV ratio
was 86.98± 3.16%, whereas these values were
25.0±15.94 and 90.56±2.15%, respectively, in the
OSAS patient group. The TV/OCV ratio of the
OSAS patient group was significantly higher than
that of the normal control group (p<0.01).
