In today's batch of MS-related abstracts from PubMed (which, by the way, you can get as an RSS feed, which I do) reports that the width of the brain's third ventricle, as measured by transcranial brain sonography, has a "good correlation" to cognitive impairment in MS patients. Here's a link to the abstract.
I've never had a transcranial brain sonograph, but I've got some relatively recent (6-9 months old) MRI images. I wonder what my third ventricle looks like- maybe I'll try to post a picture that shows my third ventricle. Unfortunately, the abstract doesn't really say whether it's larger-than-normal or smaller-than-normal ventricular width that correlates to cognitive impairment, so I'll probably just end up torturing myself unnecessarily, but hey, that's what science is all about, right?