Abstract
Obstructive sleep apnea syndrome (OSAS) is characterized by symptoms and signs of more than 5 apneas per hour (AHI) at polysomnography or 15 or more apneas per hour without symptoms. In this review, the focus will be a subgroup of patients: adult non-obese subjects with OSA and their specific features. In non-obese OSA patients (patients with BMI < 30 kg/m(2)), there are specific polysomnographic features which reflect specific pathophysiological traits. Previous authors identified an anatomical factor (cranial anatomical factors, retrognatia, etc.) in OSA non-obese. We have hypothesized that in this subgroup of patients, there could be a non-anatomical pathological prevalent trait. Little evidence exists regarding the role of low arousal threshold. This factor could explain the difficulty in treating OSA in non-obese patients and emphasizes the importance of a specific therapeutic approach for each patient.