2022/Feb/12 A Great Attending is a Stroke of Good Luck: Anand Viswanathan & Lacunar Strokes

Dr. Anand Viswanathan's after rounds reflections

Dr. Viswanathan is the Director of Telestroke Services at Mass General Brigham Healthcare and an Associate Professor of Neurology at Harvard Medical School. He is a staff neurologist on the Stroke Service and in the Memory Disorders Unit at Massachusetts General Hospital and in that capacity he models the best elements of a doctor. He is a teacher and advocate to both patient and trainee alike.

While on service Dr. Viswanathan punctuates each day by sending a reflection that is as entertaining to read as it is educational. As a senior resident trying to build my own short, crisp teaching points for rounds, I have cribbed liberally from these, and since I found them useful, I think others would too. I asked him if he would share a few, and Dr. Viswanathan said yes. Please find below an interesting foray into Lacunar shapes.


Lacune shape & Microvasculature


Hi friends,

Today we saw a patient with mild neurologic symptoms later found to have a surprisingly large, deep lacune on MRI. This prompted us talked about lacunes and their various sizes and shapes. In recent years, there has been a good amount of work focused on lacunes which were first described in detail in pathologic studies by our very own C. Miller Fisher.


1) All lacunes are not round

Although the pathologic studies and the imaging often lead us to consider lacunes as small spherical lesions in the brain, it turns out they assume a variety of shapes depending upon how proximal along the small-vessel tree that arterial lesion is (see below from our colleague Dominique Hervé’s Stroke paper in the genetic stroke disease, CADASIL: https://pubmed.ncbi.nlm.nih.gov/18948610/.

lacunar shape


2) Standardizing definitions of lacunes (or lacunar lesions)

An international consortium of colleagues has made a concerted effort to specifically define lacunes in order to better quantify them for imaging studies and to more accurately measure their cognitive effects. Effort has also been made to distinguish lacunes on neuroimaging from perivascular spaces, which are often dilated in older individuals. This work and overall goal has been described in several publications (https://pubmed.ncbi.nlm.nih.gov/23867200/ ; https://pubmed.ncbi.nlm.nih.gov/30859119/).


The figure below (from our paper in Lancet Neurology) shows how lacunes can be distinguished from all small vessel disease lesions:(https://pubmed.ncbi.nlm.nih.gov/23867200/#&gid=article-figures&pid=figure-2-uid-1)

lacunar shape and size

3) Microvasculature may affect size and shape of lacunar infarctions

Our outstanding colleague David Kleinfeld at UC San Diego has developed beautiful experimental systems to explore the microvascular structure in the brain and how this may impact brain lesions (including cerebral microinfarctions and lacunes). Remember, that Dominique’s baseball bat, donut and slab shapes are determined by branching structure and where the occlusion specifically occurs. The Kleinfeld lab has produced beautiful images such as the one below (for their website see: https://neurophysics.ucsd.edu/index.php).


lacunar vasculature

Very nice work today, team! See you tomorrow,



For more about Dr. Viswanathan:

Anand Viswanathan

He is an executive member of the Massachusetts Alzheimer’s Research Center (MADRC). His research program at the J. Philip Kistler Stroke Research Center focuses on the contribution of stroke and vascular risk factors to dementia. His group has engaged in numerous multidisciplinary interactions and collaborations, including with artists and writers, in order to further develop and foster humanism in medicine among young physicians and medical researchers.

Tune in next time for Dr. Viswanathan’s reflections on: Environment and disease, cognitive stress tests, and German World Cup football

If you want to recognize a clinician educator in neurology, neurosurgery, and psychiatry in the Boston area, please write-in bostonsocneurologypsychiatry@gmail.com, or if you want to share your own short teaching points in your field, please submit to the blog!