Distribution Patterns of Brain MS Plaques Among Iranian Patients: A Gender-Based MRI Study

Aims This study aimed to characterize the distribution of multiple sclerosis (MS) plaques in the brains of Iranian patients using MRI and to assess gender-based differences in lesion involvement. Findings were compared with international data to identify region-specific patterns. Methods We conducted a retrospective analysis of 131 Iranian patients with MS (89 women and 42 men) diagnosed according to the 2017 McDonald criteria. Brain and orbit MRIs, obtained with and without intravenous gadolinium, were reviewed to identify lesion distribution. Gender-based differences in lesion prevalence and patterns were examined. Statistical analysis included Chi-square or Fisher’s exact tests, with adjustment for multiple comparisons using the Benjamini–Hochberg false discovery rate (FDR) procedure (α = 0.05). Results The most frequently affected regions were the periventricular white matter (93.9%), followed by the pericallosal white matter (91.6%) and the brainstem (80.2%). The optic nerve and cerebellum showed the lowest involvement. Male patients had a significantly higher number of affected regions than female patients. Although several regions showed nominal gender differences, only the periaqueductal region remained statistically significant after correction for multiple comparisons, while other regions demonstrated trends that did not reach corrected significance. Conclusions MS lesions in this population showed a clear regional distribution pattern, with prominent involvement of periventricular and brainstem regions. While males had a greater number of affected regions, robust region-specific gender differences were limited after correction. These findings highlight the importance of population-specific studies in understanding MS heterogeneity and support the need for larger studies to further clarify gender-related patterns.