x-ray radiation and the risk of multiple sclerosis: do the site and dose of exposure matter?

background: the sporadic cases of radiation-activated multiple sclerosis (ms) has been previously described, with a few studies focused on the relationship between radiation and the risk of ms. the aim of our study was to evaluate the association between history of x-ray radiation and ms.   methods : this case-control study was conducted on 150 individuals including 65 ms patients and 85 age- and sex-matched healthy controls enrolled using non-probability convenient sampling. any history of previous x-ray radiation consisted of job-related x-ray exposure, radiotherapy, radiographic evaluations including chest x-ray, lumbosacral x-ray, skull x-ray, paranasal sinuses (pns) x-ray, gastrointestinal (gi) series, foot x-ray and brain ct scanning were recorded and compared between two groups. statistical analysis was performed using independent t test, chi square and receiver operating characteristics (roc) curve methods through spss software.   results : history of both diagnostic [or=3.06 (95% ci: 1.32-7.06)] and therapeutic [or=7.54 (95% ci: 1.59-35.76) x-ray radiations were significantly higher among ms group. mean number of skull x-rays [0.4 (sd=0.6) vs. 0.1 (sd=0.3), p=0.004] and brain ct scanning [0.9 (sd=0.8) vs. 0.5 (sd=0.7), p=0.005] was higher in ms group as well as mean of the cumulative x-ray radiation dosage [1.84 (sd=1.70) msv vs. 1.11 (sd=1.54) msv p=0.008].   conclusion : our study was one of the first to show higher history of x-ray radiation in patients with ms compared to healthy controls. a possible association was also found between the dose and the site exposed to x-ray radiation and risk of developing ms.