الفهرس 
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Abstract
Background: Multiple Sclerosis (MS) is a chronic demyelinating disease of the Central Nervous System. MS attacks the myelinated axons in the CNS, destroying the myelin and the axons to varying degrees. The course of MS is highly varied and unpredictable. In most patients, the disease is characterized initially by episodes of reversible neurological deficits, which is often followed by progressive neurological deterioration over time.
Working memory refers to the cognitive system responsible for temporarily holding and manipulating information necessary for ongoing mental tasks. It plays a vital role in various cognitive processes, such as attention, problem-solving, decision-making, and learning. Working memory dysfunction in RRMS can have a significant impact on daily functioning, including academic and occupational performance, social interactions, and overall quality of life.
Furthermore, working memory dysfunction is a well-documented cognitive impairment in individuals with relapsing-remitting multiple sclerosis (RRMS). RRMS is the most common form of multiple sclerosis (MS), a chronic autoimmune disease characterized by inflammation, demyelination, and neurodegeneration in the central nervous system. While MS primarily affects the white matter of the brain, cognitive impairments, including working memory deficits, can also occur due to the involvement of cortical and subcortical regions.
Although, the exact underlying mechanisms of working memory dysfunction in RRMS are complex and multifactorial, the disease process in MS involves inflammatory demyelination and axonal damage, leading to disrupted neural communication and impaired information processing. Lesions in specific brain regions, particularly the frontal and parietal lobes, which are crucial for working memory functioning, can contribute to cognitive deficits.
Additionally, gray matter atrophy and cortical thinning, which are common in RRMS, can further disrupt neural networks involved in working memory. Alterations in functional connectivity and neurotransmitter imbalances, such as reduced dopamine levels, may also contribute to working memory dysfunction.
Various neuropsychological tests and neuroimaging techniques have been employed to assess working memory impairments in RRMS. These assessments typically involve tasks that require the manipulation, maintenance, or updating of information over short periods. Individuals with RRMS often exhibit reduced performance in tasks requiring attentional control, information updating, and mental flexibility.
Aim: The primary objective of the study is to assess the relation between working memory dysfunction and clinical and MRI findings in relapsing remitting multiple sclerosis in a sample of Egyptian patients attending Nasr City health insurance multiple sclerosis outpatient clinic.
Patients and Methods: This is comparative case-control study involving 30 patients with clinicaly definite relapsing remitting multiple sclerosis diagnosed as MS according to revised Mcdonald criteria attending Nasr City health insurance multiple sclerosis outpatient clinic, and 30 healthy controls matched for age, sex and educational level, they were selected from general population through personal communication and hospital workers.
All MS patients, and healthy controls were subjected to complete medical history including personal history, past history, family history suggesting autoimmune diseases, and history of current illness, in addition to complete Physical, neurological examination, also, routine laboratory investigations, moreover, neurophysiological assessment including digit span test, number back test and Wisconsin card sorting test, Expanded Disability Status Scale (EDSS), and brain MRI with considering number of lesions.
Results: we observed that MS patients had statistically significant lower means of digital span, and Wisconsin card sorting tests than the control group with (4.87±1.2 vs 6.57±1.25), and (42.37±4.9 vs 48.87±2.9), respectively. In addition, MS patients had statistically significant higher frequency of no correct answers in Number correct back test than the healthy group with (56.7% vs 6.7%).
Regarding age, we found non-significant difference between the two groups in terms of the three measurements. Moreover, mean of digital span was significantly higher among males compared to females with (6.4±1.5 versus 5.38±1.39), however, there was no statistically significant difference regarding number correct back and Wisconsin card sorting test between males and females.
Regarding disease duration, age at onset, and EDSS there was weak negative non-significant correlation between disease duration and digital span, as well as Wisconsin scoring test, however, there was positive non-significant correlation with number correct back test.
Lastly, there was no significant correlation between the family history, number of relapses, and MRI lesions with MS patients in our study.
It’s concluded that MS patients have significantly more cognitive impairment, and working memory dysfunction than healthy people, in addition, more severe affection was observed in older patients, males, patients with higher disease duration, and age of onset less than 20 years. However, there is no relation between family history, number of relapses, and MRI lesions and MS patients.