Multiple sclerosis (MS) is one of the leading causes of disability in young adults. The onset of MS during developmental age makes pediatric patients particularly susceptible to cognitive impairment, resulting from both disease-related damage and failure of age-expected brain growth. The median age at first attack in most POMS cohorts is between 11 and 13 years [
11]. Cognitive impairment is defined as having one-third or more test scores in the impaired range [
12]. The neurodegenerative and inflammatory impact of MS meets the brain during a critical time period and may disturb myelination process and other maturation processes of the brain [
13]. Radiological evaluation is focusing on the presence of typical WM lesions of MS, involving their morphology and location. Another important component of MS pathology is neurodegeneration which cause brain atrophy—has been identified as an important prognostic factor for disease progression in the research field [
14]. In our study, we compared MS and controls, regarding the cortical thickness of all parts of temporal lobes including “superior, middle and inferior temporal thickness, fusioform, enthorinal and para hippocampal thickness” in both hemispheres. We found a difference in the thickness of temporal lobe cortex, the lowest value was related to the MS group. In the same context a study done in 2020, comparing GM volume between MS group and healthy control group, the results showed GM volumes were significantly decreased by approximately 5% in both sexes in MS group [
15]. In addition, Sugijono et al. showed that significant reductions in GM volume, especially in the frontotemporal cortex, and this GM volume reduction progressively occurred in patients with progressing lesions in their WM [
16]. We also study the relative thalamic volumes in both hemispheres comparing it with the controls and we found that there was significant difference between the two groups, the lowest value was found in MS group. According to Minagar et al., the thalamus is the most vulnerable structure to be atrophied in all MS subtypes. Nuclei of the thalamus are GM structures which influence cognition, sensory and motor functions due to their major role in activation of the cortex and relaying sensory information to the higher centers of the cortex. A wide range of neuropsychological manifestations, including cognitive impairments and motor deficits found in MS patients are due to involvement of these structures, which might become a biomarker of disease progression [
17]. Another study reported that, in comparison to healthy controls the reduction in thalamic volumes in MS patients was about 17%, with a significant correlation between the width of the third ventricle and thalamus atrophy (r = − 0.59;
p < 0.05), also atrophy in GM Subcortical structures occurred in almost all MS patients, also the rate of atrophy of subcortical GM in MS patients was faster than that of other brain areas [
18].We studied the cognitive functions of the MS group using the fifth version of Standford–Benit test, we found in nonverbal subtests that knowledge and quantitative reasoning are the most affected cognitive domains, while in verbal subtests, knowledge and working memory are the most affected cognitive domains, also non-verbal IQ was more affected than verbal and full IQs. In MS group, we did a correlation between temporal lobe cortex thicknesses and relative thalamic volumes with Standford–Benit Test-5. We found that there were a significant correlations between impairment that was found in specific cognitive domains like fluid reasoning, quantitative reasoning and visual spatial processing with decrease in volumes of temporal lobe cortical thicknesses and relative thalamic volumes. In 2014 a study was done used structural and functional MRI to understand the mechanisms responsible for cognitive impairment in POMS, in Comparing to the controls, MS patients showed reduced resting-state functional connectivity of the precuneus, a multivariable model identified diffusivity abnormalities of the cingulum and corpus callosum and the precuneus as the covariates more strongly associated with cognitive impairment (C-index = 0.99) [
19]. Till et al. dictated that thalamic volume accounted for significant incremental variance in predicting global IQ, processing speed, and expressive vocabulary and was the most robust MRI predictor of cognitive impairment relative to other MRI metrics [
20].
A longitudinal prospective, study of MS patients identifies of GM MRI markers and associated clinical symptoms and impact to unemployment. Subcortical deep grey matter (SDGM) atrophy showed a strong association with unemployment, whereas cortical atrophy showed a weaker, yet significant relationship with employment status. Thalamus, pallidus, putamen and hippocampus are the more area out of the SDGM structures that have the lowest volumes, and are found to be associated with unemployment [
21]. This is in line with a cross sectional study of 50 RRMS patients showing significantly more thalamic atrophy in unemployed patients [
22]. Lorefice et al. documented that, thalamus has the smallest volume among the reported scGM structures, observed in cognitive impaired patients, and this result agree with previous studies that documented the relation between thalamic atrophy and cognitive decline in RRMS patient
s, indicating its important predictor tool for memory and executive deficits [
23]. In 2016 a study done showed alterations in right and left thalamic shape were found to correlate with change in performance on the symbol digit modality test (
p value = 0.011) [
24].
Our study has some limitations. First, lack of data about our patients’ base line cognitive function before or at time of their diagnosis by MS. Second, we did not assess the disease modifying therapy effect on both cognitive function and on brain volume loss. Finally, we did not involve the number of relapses nor the Expanded Disability Status Scale in our study.