I spoke with a colleague recently about the topics for our local stroke convention in the fall and we shrugged shoulders: nothing new really. Really? Quite to the contrary. I stumbled upon a patient last week that had the curious combination of a horizontal gaze palsy to the left with only slight proximal paresis of the left arm, maybe some dysarthria, but you couldn’t quite tell, because his local accent was so thick. And his MRI: shows a microangiopathic lesion only in the right internal capsule, in the posterior crus right behind the genu, perhaps touching the latter a tiny little bit. No thalamic involvement, nothing else.
We reviewed the functional anatomy of the horizontal gaze system and localized the various structures (such as the frontal eye fields, the capsule, the PPRF, MLF, IIIrd and VIth cranial nerve nuclei) in an MRI. I am always surprised how hard this can be, but we use Kretschmann’s atlas to do the main work. The rest can be left to Brazis’ localization book, which – incidentally – has been edited in 2012.