| Objective:The aims of this study were to investigate the MR characteristics of patients suffering from obstructive sleep apnea hypopnea syndrome (OSAHS), to assess the clinical application of upper airway by routine MRI and brain multivoxel 1H magnetic resonance spectroscopy (1H-MRS) in patients with OSAHS.Materials and Methods:20 patients (case group) who clinical diagnosed of moderate to severe OSAHS and 20 age-gender matched healthy volunteers (control group) underwent routine MRI of upper airway and brain multivoxel'H-MRS examinations during wakefulness. The upper airway was divided into retropalatal region (RP), retroglossal region (RG) and epiglottal region (EPG). The narrowest section of three regions were measured respectively, the smallest one was defined as the minimum area of upper airway. The ratios of N-acetylaspartate (NAA) to creatine (Cr) and to choline (Cho), as well as the ratios of Cho to Cr were recorded. The presence or absence of Lactate (Lac) was also observed. The related clinical indexes included the apnea hypopnea index (AHI) and the average saturation of blood oxygen during nighttime (SpO2). All of these data were analyzed.10 severe OSAHS patients who underwent the improved Uvulopalatopharyngoplasty (UPPP) were followed up at the time of postoperative 2 to 6 months.Results:Compared to control group, the minimum section area of RP regions and RG regions, as well as that of the upper airway in case group were statistically smaller (P<0.05). The minimum section area of the EPG of case group was slightly smaller than that of control group, however, there was no significant difference between the two groups (P>0.05). In case group, cortical sulci was found slightly widened in 11 cases, the signal intensity of clivus marrow became reduced in 5 cases. In the region of anterior central gyrus of frontal lobe and centrum ovale, all of the 20 cases presented NAA/Cr, NAA/Cho decreased and Cho/Cr increased significantly. 14 cases in gyrus frontalis inferior,15 caeses in posterior central gyrus,17 cases in supramarginalis gyrus,14 cases in gyrus temporalis superior, and 13 cases in gyrus temporalis medius showed the above changes respectively. There were statistical significances between two groups (P<0.05). Lac was not detected in the two groups. There were negative correlations between AHI to SpO2 and the minimum section area of upper airway (P<0.05). In the region of centrum ovale, the negative correlation between AHI to SpO2 and NAA/Cho were also observed(P< 0.05), while no correlation to NAA/Cr or Cho/Cr(P>0.05). In 10 cases performed improved UPPP, the minimum section area of RP and RG as well as upper airway were significantly increased (P<0.05). Compared with pre-UPPP, there was no significant change of the minimum section area of EPG for patient post-UPPP (P>0.05). Multivoxel 1H-MRS showed increased NAA/Cho and NAA/Cho (P<0.05) and decreased Cho/Cr (P<0.05) in the reigion of centrum ovale, gyrus frontalis inferior, anterior central gyrus, posterior central gyrus, supramarginalis gyrus, gyrus temporalis superior, and gyrus temporalis medius after improved UPPP. Lac was still not detected after UPPP.Conclusions:RP was the most common obstructive position of OSAHS patients. Bone narrow recovered in the patients with severe OSAHS due to long-term hypoxia. Multivoxel 1H-MRS could sensitively detect the changes of cerebral metabolism in patients with OSAHS. Anterior central gyrus of frontal lobe and centrum ovale were more sensitive than other regions to brain ischemia and hypoxia. Improved UPPP not only relief airway obstruction, but also could effectively improve the cerebral metabolism for patients with OSAHS. The combination of upper airway routine MRI and brain multivoxel 1H-MRS examinations could provide valuable diagnostic and therapeutic information for patients with OSAHS pre-and post- improved UPPP, and play an important role to obviously avoid or decrease the risk of cerebral infarct. |
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