Lacunes and cognitive decline

Neurologists evaluating patients with cognitive impairment or dementia are regularly confronted with the task of determining the importance of lacunar infarcts on brain imaging scans. Best seen on MRI, these lesions occur in both deep gray and white matter (WM) and are most often commingled with varying degrees of WM hyperintensity (WMH), further complicating the matter. Subcortical lacunes and WMH have been linked with vascular cognitive impairment, a concept that is evolving¹; further, when severe, these findings suggest the diagnosis of subcortical ischemic vascular dementia.² However, the relative contribution of lacunes and WMHs to cognitive decline is controversial. Whereas the clinical relevance of lacunes to motor and sensory syndromes is widely accepted,³ the degree to which cerebral lacunes affect cognitive function has been less clear. Dementia associated with multiple lacunes—the état lacunaire of Pierre Marie⁴—has been recognized for over a century, but the cognitive dysfunction resulting from one or a few lacunes is often considered negligible.³ Further consideration of this question is warranted, based on the evidence that even a single WM lacune …