In multiple sclerosis (MS), active lesions are contrast-enhanced with optic neuritis, whereas in CADASIL, there is sparing of the infratentorial brain and spinal cord [16]. However, the gold standard for the diagnosis of CADASIL is currently genetic testing that identifies the distinctive cysteine-altering mutations in the NOTCH3 gene; heterozygous mutations in the NOTCH3 (NM_000435.2)c.457C>T p(Arg153Cys) were detected in our patient following his genetic study. Here, NOTCH3 is linked to optic neuritis.