The detection of T2 hyperintensities within the CNS, often termed small vessel disease, has been linked to development of cognitive impairment and is though to be driven by vascular risk factors such as hypertension.  MRI-visible perivascular spaces (PVS), see fig below, appear to be reliable MRI bio-markers of small vessel disease and have been associated with development of dementia and cognitive dysfunction in the elderly.  In this issue of JNNP, an elegant study by Hurford and colleagues report an absence of any association between PVS and cognitive impairment.  Interestingly, hypertension was a risk factor for PVS occurrence.

What does this, however, mean?  Are the lesions in the wrong place for dementia, is a critical lesion load required for dementia.

READ MORE AT:  http://jnnp.bmj.com/content/85/5/522.full

Perivascular space in white square.  PVS are differentiated from lacunae by the smaller size (< 3 mm for PVS) and being a sharpy delineated structure of CSF (dots or lines)

that follow the plane of the small blood vessel, absence of surrounding hyperintensity.