Association Between the Severity of Positional Obstructive Sleep Apnea and MRI Findings

Project no. 24024 · Status: Kapanmış (Yayın bekleniyor) · 2022

Summary

In patients diagnosed with obstructive sleep apnea (OSA), disease severity is determined by polysomnography (PSG) using the apnea–hypopnea index (AHI), defined as the number of apnea and hypopnea events per hour of sleep. AHI varies according to sleep stages and body position during sleep. Positional obstructive sleep apnea (POSA) is characterized by an increase in OSA severity in the supine position. Supine-isolated POSA is defined as a supine AHI at least twofold higher than the non-supine AHI, provided that the non-supine AHI remains within normal limits (< 5 events/h). Supine-predominant POSA is defined as a condition in which the total AHI exceeds 5 events/h and the supine AHI is at least twice the non-supine AHI.In patients with POSA, in whom OSA severity markedly increases in the supine position, cephalometric analysis, computed tomography, and magnetic resonance imaging (MRI) have been widely used to evaluate upper airway alterations or pathologies contributing to this condition. Among these modalities, MRI is considered the preferred imaging technique owing to its superior soft tissue contrast and lack of ionizing radiation. MRI allows assessment of the maximum thickness and length of the soft palate, posterior airway space (PAS) diameters at the nasal–occlusal and mandibular planes, as well as the PAS cross-sectional area and tongue volume. However, the number of studies evaluating the relationship between MRI findings and POSA remains limited. These measurements are thought to facilitate a more precise evaluation of dynamic upper airway changes and obstruction levels, enable prediction of OSA and POSA in patients undergoing upper airway MRI for other indications, and help identify patients who are more likely to benefit from positional therapy.The present study aimed to investigate changes in upper airway cross-sectional areas between supine and non-supine positions in patients with POSA and to evaluate the relationship between these changes and polysomnographic parameters. Of the patients, 77.8% were male, with a mean age of 50.0 ± 13.9 years. The mean body mass index was 26.4 ± 2.8 kg/m², and the mean neck circumference was 39.6 ± 3.0 cm. Snoring (97.8%) was the most common symptom, while hypertension (35.6%) was the most frequent comorbidity. Transition from the supine to the lateral position resulted in significant reductions in airway length and retropalatal diameter (supine: 76.9 mm vs. lateral: 73.6 mm; retropalatal anteroposterior diameter: 13.7 mm vs. 11.6 mm). Men exhibited significantly greater differences in retropalatal airway diameter and tongue fat volume compared with women. Increasing AHI was associated with a significant reduction in airway length and diameter changes.Marked anatomical differences in the retropalatal and retroglossal regions were observed between the supine and lateral positions in patients with POSA. MRI plays a critical role in identifying the site, underlying cause, and severity of upper airway obstruction in the diagnosis of POSA.

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