Bithalamic paramedian infarcts are uncommon. This stroke results in a complex clinical syndrome.
We report four cases of bithalamic paramedian infarcts with a presumed mechanism of occlusion of a single thalamic paramedian artery.
This normal anatomic variant corresponds to an asymmetrical common trunk for the two thalamosubthalamic paramedian arteries arising from a P1 segment (type IIb in the G. Percheron classification dating from 1977). A literature analysis (from 1985 to 2006) allowed us to identify the most widely reported clinical signs. Four main clinical findings are described: vertical gaze palsy (65%), memory impairment (58%), confusion (53%) and coma (42%). We also found these symptoms in our patients but rarely associated; however, all four patients had exhibited episodes of drowsiness. In this article, we discuss the anatomy-function correlation responsible for such clinical variability.
Clinicians should be aware of this diagnosis to better understand the imaging results which provide confirmation. Although the literature describes frequently severe consciousness disorders such as coma, this diagnosis must also be considered in patients presenting a simple fluctuation of consciousness, e.g. hypersomnia.