The most common hereditary cerebral small vessel disease, associated with strokes and vascular dementia, is known as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). CADASIL is caused by mutations of the NOTCH3 gene. Since most pathogenic mutations at the protein level result with cysteine being replaced with another amino acid or another amino acid being replaced with cysteine, they are referred to as stereotyped mutations. A 55-year-old male patient, suddenly affected by speech disturbances, was diagnosed with a sporadic case of CADASIL on the basis of radiological imaging, particularly an magnetic resonance imaging scan. The diagnosis was conclusively confirmed by genetic testing, which revealed one of the rarer mutations, located in one allele of the NOTCH3 gene, namely p.Arg207Cys, reflecting at the DNA level a transition changing cytosine to thymine in position 619. In magnetic resonance imaging, classical radiological changes were seen, along with the presence of microhaemorrhages in subcortical nuclei, which is an atypical clinical manifestation of the disease. Despite the advanced cerebral changes, the patient continued to be professionally active. Currently, no effective treatment for the condition is available.