| Objective:This study aimed to analyze the characteristics of substantia nigra hyperechogenicity(SN+)and cerebral blood flow(CBF)changes detected by transcranial sonography(TCS)in patients with obstructive sleep apnea(OSA),and to investigate the differences of bilateral SN damage and CBF in OSA patients.It also analyzed the correlation between parameters of the middle cerebral artery(MCA)and the severity indicator of OSA.Such the specific characteristics of TCS imaging findings in OSA patients were studied.Methods:A group of right-handed men diagnosed with OSA by the Sleeping Center were recruited from August 2018 to August 2020,and the clinical data were relatively complete.According to apnea-hypopnea index(AHI)the included patients were divided into mildmoderate group(5≤AHI<30)and severe group(AHI≥30).A group of male right-handed simple snore volunteers who were excluded from OSA were included.All of the subjects underwent TCS examination,the echo signal of the SN,the width of the third ventricle,the pulsatility index,resistance index and velocity of the middle cerebral artery on both sides before and after breath holding were recorded,and the changes of the above indexes were analyzed.Results:Finally,155 OSA patients(54 mild-moderate and 101 severe)and 56 controls were enrolled in this study.1.The proportions of SN+in the mild-moderate group,the severe group and the control group were 16.67%(9/54),12.87%(13/101)and 8.93%(5/56),respectively,and P>0.05.The incidence of abnormal widening of the third ventricle(V3)were 1.85%(1/54),2.97%(3/101)and 0%(0/56),respectively,and P>0.05 either.The larger lateral areas of SN+in the three groups were(0.31±0.16)cm2,(0.25±0.15)cm2,and(0.29±0.04)cm2,respectively,and the difference was not statistically significant(P>0.05).In addition,the larger lateral area of SN+in OSA patients was not correlated with age,Epworth sleepiness scale(ESS)score,lowest SpO2%during the sleep time(LSpO2),time ratio of oxygen desaturation lower than 90%(T90),AHI,and oxygen desaturation index(ODI)(P>0.05).2.After breath-holding,the peak systolic velocity(PSV)and the mean velocity(mV)of the MCA increased significantly,while the pulsatility index(PI)and the resistance index(RI)decreased significantly in the three groups(P<0.05).In the breath-hold state,the breathholding index(BHI)of the left and right sides were different among the three groups(control group>mild-moderate group>severe group)and the differences were statistically significant(P<0.05).3.In OSA group,the ratio of SN+in the left side was 12.90%(20/155),and that in the right side was 1.94%(3/155),and the difference was statistically significant(P<0.05).Similar findings were found in the mild-moderate and the severe OSA subgroups.In control group,the ratio of left SN+was 7.14%,higher than that in the right side(1.79%),but the difference was not statistically significant(P>0.05).In OSA patients,the PI of the left MCA(0.60 ± 0.11)was lower than that of the right MCA(0.64 ± 0.14)and the RI of the left MCA(0.47 ± 0.09)was higher than that of the right MCA(0.46±0.06),and the differences were both statistically significant(P<0.05).In control group,the left MCA PI(0.69±0.12)was also lower than the right side(0.72 ± 0.20)and the left MCA RI(0.52±0.15)was also higher than the right side(0.49±0.08),but the differences were not statistically significant(P>0.05).4.Before breath-hold there was no correlation between the blood flow parameters of OSA patients and AHI(P>0.05).Nevertheless,the bilateral PI and RI were correlated with AHI and age(P<0.05)after breath holding.The PI of the right MCA was negatively correlated with AHI(r=-0.180,P=0.025)and positively correlated with age(r=0.336,P<0.001).Conclusion:In this study,TCS image characteristics of OSA patients with different severity were analyzed,and the results showed that:1.The cerebrovascular reactivity of OSA patients is impaired,especially in the severe group;2.The damage is asymmetrical in both hemispheres of the brain in OSA patients,which may be related to the dominant hand and the cross domination of the brain;3.There is no correlation between the detection rate of SN+and the severity of OSA,and there is no significant difference in the proportion of SN+between OSA patients and simple snorers. |
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