| Objective:To study the cognitive impairment and the related factors in patients with multiple sclerosis (MS). To explore the pathologic changes in the brain areas corresponding to specific cognitive function and underlying mechanism of cognitive imparirment in patients with MS by Diffusion-Tensor Imaging (DTI) study.Methods:1.13 patients with MS and 13 age-matched healthy controls admitted in the department of Neurologour or clinic of our hospital since March 2008 to January 2010 were recruited in this study, their intelligence level and memory level were evaluated by means of Wechsler Adult Intelligence Scale and Memory Scale Verbal and Fluency test.2.13 patients and 13 control subjects were administered a test of Diffusion-Tensor Imaging examination. Correlation analysis were made to determine the relationship between FIQ,VIQ,PIQ or MQ and DTI value.Result:1. VIQ, PIQ, FIQ and MQ of patients in the brain or brain/spinal cord group were significantly lower than patients in the spinal cord group(P<0.05). Age significant affected MQ (P<0.05); years of education significantly affected FIQ and MQ (P <0.05). 2. The total average number of the words (vegetables, animals, fruit) said in 1 minute of the MS group were significantly less than that of the control group (P<0.05);the digit span and digit symbol of MS Group were significantly lower than the control group (P<0.05). the age had a significant effect on the digit span (P<0.05); years of education (year) significantly affected on the semantic fluency, digit span and digit symbol (P<0.05).3. DTI imaging studies show that:Elongated T2 signal can be seen on T2 phase in lesions center. MD in lesions were significantly higher, FA in lesions was significantly reduced even to 0 than in other parts (P<0.05). PWM showed both increased diffusivity and decreased anisotropy compared with the NAWM. Significant increase of MD in genu of corpus callosum and thalamic (P<0.05) were demonstrated in patients with impaired cognition compared with those with normal cognition. Significant reduced FA in genu of corpus callosum, anterior limb of internal capsule, external capsule, occipital lobe, putamen (P<0.05) were demonstrated in patients with impaired cognition compared with those with normal cognition. Significant increase of MD in occipital lobe (P<0.05) was demonstrated in patients with impaired verbal fluency compared with those with normal verbal fluency. Significant reduced FA in posterior limb of internal capsule, occipital lobe, caudate nucleus, putamen (P<0.05) were demonstrated in patients with impaired verbal fluency compared with those with normal verbal fluency.4. Positive correlation between FIQ, VIQ, PIQ and FA in occipital lobe, negative correlation between FIQ, MQ and MD in genu of corpus callosum, negative correlation between VIQ and MD in frontal lobe, negative correlation between verbal fluency and MD in anterior limb of internal capsule and frontal lobe, positive correlation between verbal fluency and FA in frontal lobe and occipital lobe, external capsule, frontal lobe and occipital lobe, negative correlation between digit span and MD in anterior limb of internal capsule and frontal lobe, positive correlation between digit span and FA in frontal lobe and putamen were demonstrated to be of statistic significance by correlation analyse (P<0.05).Conclusions:1. Impairments of cognitive and multiple executive functions exist in the multiple sclerosis patients.2. Diffusion tensor imaging (DTI) is more sensitive to MRI for non-invasive examination, especially in minimal pathological changes. DTI can be useful to diagnose, prevent and cure the multiple sclerosis.3. Impairments of executive functions are beyond the limit of prefrontal lobe include a series of discontinuous regions (such as white matter of occipital lobe or frontal lobe, anterior limb of internal capsule and putamen) in the multiple sclerosis patients. The different cognitive functions are related to the integrity of the different area of white matter and subcortical gray matter.
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