Comparative Study Of Brain FMRI With Olfactory Stimulation In Neuromyelitis Optica Spectrum Disease And Multiple Sclerosis

Objective:To observe the characteristics of brain functional magnetic resonance imaging(fMRI)under olfactory stimulation in patients with neuromyelitis optica spectrum disorders(NMOSD)and multiple sclerosis(MS),compare the differences of brain functional activation areas between NMOSD patients and MS patients,and explore the characteristics of olfactory-related brain networks between NMOSD and MS,in order to provide a new reference index for the clinical differentiation and disease evaluation of NMOSD and MS.Methods:19 patients in the NMOSD group and 16 patients in the MS group who met the diagnostic criteria were enrolled.19 sex-and age-matched healthy controls were also recruited.All subjects were first assessed for olfactory function using a visual analogue scale(VAS).Then,olfactory stimulation was alternately performed with volatile gases(lavender,rose solution),and task-state fMRI scanning was also performed.Metlab2013a and SPM8 software were used to analyze task-state fMRI image data.Brain region activation in the NMOSD,MS,and control groups was analyzed within groups using the one-sample t-test.Differences in brain activation among three groups were compared using one-way analysis of variance,followed by multiple comparison analysis of differences between each two groups.Result:1.VAS scores comparisonThe VAS scores of NMOSD group,MS group and control group respectively were(2.79±0.47),(2.84±0.50)and(4.47±0.46).There were significant differences in VAS scores between NMOSD group and control group(P<0.001),there were significant differences in VAS scores between MS group and control group(P<0.001).There was no significant difference in VAS scores between NMOSD group and MS group(P>0.05).2.fMRI results①These activated brain areas in control group included bilateral insula,bilateral superior parietal gyrus,bilateral superior temporal gyrus,bilateral cuneus,bilateral posterior central gyrus,bilateral paracentral lobule,bilateral medial cingulate cortex,bilateral supplementary motor area,right precentral gyrus,right rolandic operculum,right supramarginal gyrus,left inferior temporal gyrus,left fusiform gyrus,right putamen,right middle frontal gyrus,right superior occipital gyrus,left cerebellum(P<0.05).These activated brain areas in MS group included bilateral precentral gyrus,bilateral dorsolateral superior frontal gyrus,bilateral supplementary motor area,left lingual gyrus,left paracentral lobule(P<0.05).These activated brain areas in NMOSD group included bilateral insula,bilateral amygdala,bilateral hippocampus,bilateral parahippocampal gyrus,bilateral rolandic operculum,bilateral precentral gyrus,bilateral posterior central gyrus,bilateral putamen,bilateral superior temporal gyrus,bilateral Heschl’s gyrus,bilateral cerebellum,left orbital inferior frontal gyrus,left triangle inferior frontal gyrus,left opercular part of inferior frontal gyrus,left caudate nucleus,left middle frontal gyrus,left inferior temporal gyrus,left pallidum,right lingual gyrus,left fusiform gyrus,left inferior occipital gyrus,left dorsolateral superior frontal gyrus,left medial superior frontal gyrus,right superior occipital gyrus,right precuneus,right cuneus,left superior parietal cortex,left parietal inferior lobe angular gyrus,right medial cingulate cortex,left supplementary motor area(P<0.05).②Compared with control group,the brain areas of MS group which activated weaker included bilateral hippocampus,right parahippocampal gyrus,right insula,left rectus,right precentral gyrus;the brain areas of MS group which activated stronger included left paracentral lobule(P<0.05).Compared with control group,the brain areas of NMOSD group which activated weaker included left rectus,right superior temporal gyrus,right cuneus;the brain areas of NMOSD group which activated stronger included left insula,left middle frontal gyrus(P<0.05).Compared with MS group,the brain areas of NMOSD group which activated weaker included right superior temporal gyrus,left paracentral lobule;the brain areas of NMOSD group which activated stronger included bilateral insula,bilateral hippocampus,bilateral parahippocampal gyrus,left orbital inferior frontal gyrus,left triangle inferior frontal gyrus,left superior temporal gyrus,left putamen,left rolandic operculum,left middle frontal gyrus(P<0.05).Conclusions:1.It was verified that olfactory processing involves multiple brain functional areas,and there was olfactory-related brain network.2.Olfactory stimulation-fMRI can provide an objective means for the study of olfactory-related brain function in patients with NMOSD and MS,and can also be used as one of the objective methods for the assessment of olfactory function in clinical practice.3.Olfactory-related brain networks were changed in both NMOSD patients and MS patients,and there were differences in olfactory-related brain networks between NMOSD patients and MS patients,which may help to provide a new reference index for the clinical differentiation and disease evaluation of NMOSD and MS,and further study is necessary.