| Objective:Acoustic neuroma(AN)is a common benign tumor.Little is known about neuropsychological studies in patients with acoustic neuroma,especially cognitive neuropsychology,and neuropsychological abnormalities affect the quality of life of patients.The purpose of this study was to explore the effect of acoustic neuroma on cognitive function in patients with acoustic neuroma and to explain the possible mechanism of that by structural and functional magnetic resonance imaging(f MRI).Materials and methods:Part 1 We used neuropsychological tests to study the cognitive function of 69 patients with acoustic neuroma.Part 2 We used DTI data to construct the structural brain network,calculated the topological properties of the structural brain network from the graph theory,and studied the relationship between the structural brain network and cognitive function;We used the Rich club analysis to research the alter of hub nodes in patients with acoustic neuroma;Three different subnetworks were constructed by the length of nerve fibers obtained by deterministic tracking: shortrange subnetwork,middle-range subnetwork,and long-range subnetwork.We studied the global and local efficiency of different subnetworks,and analyzed the correlation with cognitive function;Connected edge analysis directly compared whether there was a difference in the number of fibers in the different brain region,and analyzed the relationship between the difference and the decline of cognitive function;We used tract-based spatial statistics(TBSS)method to analyze the difference between patients with acoustic neuroma and healthy controls from the whole brain white matter fibers,and further explored the possible relationship between this difference and cognitive function.Part 3 Using resting-state f MRI data,we calculated amplitude of low frequency fluctuation and regional homogeneity to explore the relationship between cognitive decline in patients with acoustic neuroma.Part 4 Using high resolution T1 data,we used the VBM method to study the changes of gray matter and white matter volume of acoustic neuroma and to research the relationship between gray matter and white matter volume and cognitive decline.Results:Part 1 Compared with the healthy control group,the general cognitive function,memory,executive function,attention,visual space executive ability,visual perception ability,movement speed,and information processing speed of acoustic neuroma patients decreased significantly.Hearing loss caused by left acoustic neuroma had a greater impact on cognitive function.Part 2 1.The global efficiency of acoustic neuroma was lower than that of normal people,and the local efficiency of right acoustic neuroma was also lower than that of normal people.Compared with the healthy control group,the local indexes of all patients with AN changed,including node efficiency,node shortest path,cluster coefficient,degree centrality.Through the analysis of the correlation between node efficiency and cognitive function,we concluded that the decline of node efficiency was related to cognitive dysfunction.Through the Rich club study,we found that the important nodes were mainly located in the default mode network,sensory movement network,attention network,salience network,executive control network,etc.These brain regions are related to memory,language,attention,executive control.2.Research results of constructing subnetwork based on fiber length.Compared with the healthy control group,the global efficiency of the left acoustic neuroma in the short-range,middle-range,and long-range subnetwork decreased,and the local efficiency in the short-range subnetwork decreased,while the right acoustic neuroma did not change significantly.The results of correlation analysis showed that the global efficiency of short-range and middlerange subnetworks was related to MoCA,RAVLT,SDMT,Stroop,and Trail-Making Test,and the global efficiency of long-range subnetwork was negatively correlated with StroopC,and the local efficiency of short-range subnetwork was also negatively correlated with Trail-Making Test.3.Results of edge analysis based on structural brain network of acoustic neuroma.The connections in some brain regions of patients with AN had changed.In patients with left acoustic neuroma,the areas of enhanced connectivity were related to memory and visual brain areas;the areas of weakened connections were related to the default mode(DMN),sensorimotor network,basal ganglion nucleus,and dorsolateral prefrontal lobe loop.The enhanced connection of the right acoustic neuroma involved visual network,salience network,and frontostriatal circuit of attention network and the weakened area involved the memoryrelated medial temporal lobe system.The changes of connections in these brain regions were closely related to the changes in cognitive function.4.Results of TBSS Compared with the healthy control group,the FA values of the left and right acoustic neuromas in the frontal part of corpus callosum radiation(also known as minor forceps or anterior forceps)decreased,while the FA values of the bilateral corticospinal tract and left superior longitudinal fasciculus increased;the MD values of left anterior thalamic radiation,right inferior fronto-occipital fasciculus and the occipital part of corpus callosum radiation(also known as major forceps or posterior forceps)increased;AD values of bilateral superior longitudinal fasciculus,left anterior thalamic radiation and right corticospinal tract increased;RD value of bilateral anterior thalamic radiation increased.Correlation analysis showed that the changes of DTI parameters were related to MoCA,RAVLT memory,SDMT,Stroop and Trail-Making Test.Part 3Results of resting-state MRI study: Compared with the healthy control group,the m ALFF value of the right caudate nucleus increased in the left acoustic neuroma patients and increased in the right rectus gyrus region of the right acoustic neuroma patients.No significant decrease was found in acoustic neuroma patients.The mReHo of bilateral superior frontal gyrus and middle frontal gyrus decreased in patients with left acoustic neuroma,but no increase in m Reho value was found.There was no significant change in mReHo of right acoustic neuroma patients.Part 4 We analyzed the relationship between the structural changes of gray matter and white matter and cognitive function in patients with acoustic neuroma by VBM.Results were as follows:1.Compared with the healthy control group,the gray matter volume of the left parahippocampal gyrus,fusiform gyrus,calcarine gyrus,and cuneus of the left acoustic neuroma increased,and the gray matter volume of the right parahippocampal gyrus and right fusiform gyrus of the right acoustic neuroma increased.2.Compared with the healthy control group,the white matter volume of bilateral putamen,left rectus gyrus and thalamus of left acoustic neuroma increased.No areas with reduced volume of gray matter and white matter were found.Correlation analysis showed that the increase of gray matter volume in patients with acoustic neuroma was related to attention,memory,executive function,and so on.Conclusion:The brain structure and function related to cognitive function in patients with acoustic neuroma have changed.It is confirmed that the decline of the structure and function of some brain regions leads to cognitive dysfunction,and there are also compensatory changes in structure and function after the decline of cognitive function.The mechanism of the left acoustic neuroma is different from that of the right acoustic neuroma.The left acoustic neuroma tends to decrease in structure and function,while the right acoustic neuroma tends to be compensated in structure and function,which is more resistant to hearing loss and more stable. |
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