The thalamoperforating arteries are small perforating branches supplying the thalamus, arising from two main sources: the anterior thalamoperforators arise from the posterior communicating artery and supply the anterior and medial thalamus including the anterior nucleus and mammillothalamic tract; the posterior thalamoperforators arise from the basilar tip and the posterior cerebral artery P1 segment and supply the posterior thalamus, the subthalamus, and the midbrain. They are among the smallest but most functionally critical cerebral vessels.
Bilateral paramedian thalamic infarction from occlusion of a common perforating trunk arising from the basilar tip (artery of Percheron) produces the dramatic syndrome of coma, vertical gaze palsy, and amnesia from simultaneous bilateral thalamic infarction. Unilateral anterior thalamoperforator infarction causes contralateral neglect, personality change, and memory impairment. Deep brain stimulation (DBS) for Parkinson disease and essential tremor targets the subthalamus and thalamus within the territory of the posterior thalamoperforators, requiring meticulous trajectory planning to avoid these small vessels.
Occlusion of the artery of Percheron, an anomalous single thalamoperforating trunk arising from the PCA P1 segment supplying both thalami, produces bilateral paramedian thalamic infarction with the triad of acute coma, vertical gaze palsy, and post-recovery dense amnesia, visible on DWI as bilateral medial thalamic restricted diffusion in a butterfly pattern.
