Pharyngeal CT studies in patients with mild or severe upper airway obstruction during sleep

The upper airway cross-sectional areas were studied with pharyngeal computed tomography (CT) at the nasopharyngeal, velopharyngeal, tongue base and hyoid bone levels in 119 consecutively investigated patients with a snoring complaint. According to their findings in an all-night static charge sensitive bed (SCSB) recording, the subjects were divided into four equally sized groups with increasing severity of nocturnal breathing disturbance. The body mass index (BMI) increased and the minimal cross-sectional area at the velopharyngeal level decreased consistently as a function of the severity of nocturnal breathing disturbance. The minimal cross-sectional area at the hyoid bone level showed a biphasic trend, with an initial decrease but a final increase, as the degree of nocturnal breathing disturbance aggravated. The results contradict the idea of gradually increasing anatomical narrowing of the upper airways in general as the nocturnal breathing disturbance exacerbates and support the concept of two anatomically determined entities of partial and complete upper airway obstruction during sleep.