Usefulness of Various Dynamic and Static Parameters in Sleep Mri Studies -Do Their Incorporation in Routine Reporting in Patients With Obstructive Sleepapnea Prove Valuable ?

Abstract

Background: Sleep MRI is a new emerging non invasive modality in the preoperative evaluation of patients with obstructive sleep apnoea. Rather than subjective, the aim of the study is to evaluate the competency of certain dynamic and static parameters (variables and diemensions), that can be used in day to day reporting. Incorporating such parameters, may prove to be helpful in guiding surgical decision making. Materials and Methods: A retrospective analytical study included 27 subjects with OSA aged between 18 and 70 years using 1.5 T MRI . We measured variables such as the cross-sectional area and diameter of the retropalatal and retroglossal airway during the asleep and awakened states.We also measured comprehensive airway dimensions such as antero-posterior diameter of the tongue, midline saggital diameter of tongue, intermandibular rami distance, mentum spine distance and relative size of the tongue using the spine as the posterior border of the bony confines. Results: 21 patients had significant retropalatal airway compromise, and was evidenced by statistically significant variables in awakened and asleep states. The mean minimum anterior–posterior diameter (mm) of retropalatal airway during respiratory cycle was statistically significant measuring 3.1±1.5 mm in awaken state and 1.1±1.5 mm during asleep state (p- value 0.01). The mean minimum cross sectional area during respiratory cycle was statistically significant measuring 98±11 mm2 in awaken state and 63 ±12 mm2 during asleep state (p- value 0.04). 6 patients had significant retroglossal airway compromise, and was evidenced by statistically significant. The thickness of the soft palate and the relative size of the tongue (0.5± 0.01mm) was statistically significant in these patients (p- value 0.01). Conclusion: Our study shows that retropalatal airway is a significant cause of obstruction in patients with OSA, compared with retroglossal airway. We suggest that, when the compromise of the retroplatine aiway is to be evaluated, variables such as cross sectional area and antero-posterior diameter of the retropalatal airway during the respiratory phase in asleep and awakened states proves valuable and dimensions such as soft palate thickness as tool for objective measurement of OSA. When the compromise of the retroglossal aiway is to be evaluated, the relative size of the tongue , proves offers more advantage than the variables of airway compromise such as area and antero-posterior diameter.To further evaluate if some of our parameters correlate with the outcomes of the surgeries of OSA, a multivariate analysis would have been required.