Thalamic Involvement and its Impact on Disability and Cognition in Multiple Sclerosis: A Clinical and Diffusion Tensor Imaging Study

Abstract

Grey matter involvement is suggested to have a role in the pathophysiology of multiple sclerosis (MS). Diffusion tensor imaging (DTI) at 1.5T was used to investigate the presence of damage to the normal-appearing thalamus in MS and its relationship with cognitive impairment, clinical disability, and fatigue. Thirty-one patients with MS (23 relapsing-remitting (RRMS) and 8 secondary progressive (SPMS)) with mean age 34.4± 8.5 SD were studied. Age-, sex-, and education level- matched healthy controls were recruited. They all underwent clinical assessment, neuropsychological assessment and radiological assessment using 1.5 T DTI. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured over regions of interest over the thalamus. Comparisons and correlations were made between patients and controls concerning clinical and radiological data. Patients with MS had higher thalamic FA (p=<0.001) and ADC (p=<0.001) than volunteers. Patients showed worse performance in all neuropsychological tests than controls except in Mini-Mental State Examination (MMSE). Performance in CVLT-II-SR was correlated with mean ADC over left thalamus (p=0.038). There was a significant correlation between total Expanded Disability Status Scale (EDSS) and Mean thalamic FA. Also, there were correlations between disease duration, number of attacks and mean FA over the thalamus. There were significant correlations between performance on neuropsychological tests and disease duration, number of attacks and total EDSS. Regarding fatigue, SPMS patients were more fatigued than RRMS patients (p=0.002). FSS had significant correlations with disease duration, number of attacks and total EDSS. DTI was able to detect abnormalities in normal-appearing thalamus of patients with MS. Thalamic involvement had significant relations with cognitive impairment and clinical disability in patients with MS.