With the introduction of magnetic resonance imaging (MRI), we have become increasingly aware of the process of brain maturation and ageing. While there is MRI evidence that the former may continue into the third decade, the latter starts as early as the fourth decade. Early ageing phenomena include the development of subtle loss of brain tissue with widening of the sulci and ventricular system, development of periventricular caps and bands, and dilatation of the perivascular Virchow-Robin spaces (VRS).

The VRS are extensions of the subarachnoid space that accompany vessels entering the brain parenchyma. Widening of VRS often first occurs around penetrating arteries in the substantia perforata and can be seen on transverse MRI slices around the anterior commisure, even in young subjects. …