We would like to present a case of a 51-year-old patient with two rare co-existing diseases. The patient was suffering from two tumours in the lumbar region of the spinal canal, which caused development of hydrocephalus. Diffuse white matter hyperintensities (WMH) were observed in our patient's brain imaging. She was also suffering from headaches and she had two mild strokes. We performed some further diagnostic procedures and found out that the patient was suffering from CADASIL. CADASIL was confirmed by both ultrastructural analysis and genetic testing.