Obstructive sleep apnea syndrome in patients with normal body weight: pathophysiologic, clinical and therapeutic aspects

The prevalence of obstructive sleep apnea syndrome (OSAS) in the general population is considerably high. The epidemiologically most important factor is obesity, since increased adipose tissue leads to alterations in upper airway anatomy and function that can trigger the mechanisms underlying the syndrome. While the bulk of published studies focus on OSAS in patients with an elevated body mass index (BMI), few have investigated the anatomical and pathophysiologic implications of OSAS in patients with normal body weight. In a previous study, the authors found that among these patients the primary anatomic anomaly contributing to the onset of OSAS was hypertrophy of the base of tongue, while septal deviation was a concurrent cause of the syndrome. Morphometric and physiologic studies have highlighted several other differences between OSAS sufferers with normal and those with elevated BMI. With this review the authors describe the anatomic, functional, clinical and therapeutic aspects of OSAS in patients with normal body weight.