Mohammad Ayyobi Nia - Department of Medicine, Faculty of Medical Sciences, Azad University of Medical Science, Mashhad, Iran
Seyed Hossein Vaezzadeh - Department of Medicine, Faculty of Medical Sciences, Azad University of Medical Science, Mashhad, Iran
Hadi Khodadadi - Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Saeed Naghibi - Department of Medicine, Faculty of Medical Sciences, Azad University of Medical Science, Mashhad, Iran

Multiple sclerosis is one of the most common neurological disorders and the third cause of neurologic disability in young adults. The disease isclassified into those diseases that myelin membrane of nerves is destroyed. Involvement of thalamus in this disease can cause cognitive impairment and motor disabilities and can reduce quality of life. Clinical manifestations include loss of vision, ataxia, anxiety, paresthesia, loss of sensation, weakness, spasticity, ataxia, and bladder dysfunction. Materials and Methods: This study was performed in cross sectional analysis method. 40 patients were enrolled in a non-probabilistic method with informed consent and considering entry criteria.Then, the EDSS questionnaire was completed and the size and volume of thalamus were examined by MRI and the largest axial section was considered. Results were analyzed by SPSS. Results: In this study, the distribution of age and sex among the participants was: 23 women (57.5%) and 17 men (42.5%) with a mean age of 36.3 ± 9.3 as well as, 15 (37.5%) were single and 25 (62.5%) were married. Bachelor’s degree and higher (32.5%) and housewives (30%) were the most frequent. The mean duration of disease was 3.5 ±1.4 years. The results in this study showed that significant reverse linear correlation between thalamus volume and disability (P> 0.05) and thalamus size and disability (P> 0.05) and direct linear relationship Between thalamus size and thalamus volume (P> 0.05). Conclusion: Generally, it can be concluded that in patients with multiple sclerosis, decreasing the size and volume of thalamus increases the incidence of patients’ disability.