Complex neurological symptoms in bilateral thalamic stroke due to Percheron artery occlusion

Abstract

The artery of Percheron is a rare anatomical variant where a single thalamic perforating artery arises from the proximal posterior cerebral artery (P1 segment) between the basilar artery and the posterior communicating artery and supplies the rostral mesencephalon and both paramedian territories of the thalami. Almost one-third of human brains present this variant. Occlusion of the artery of Percheron mostly results in a bilateral medial thalamic infarction, which usually manifests with altered consciousness (including coma), vertical gaze paresis, and cognitive disturbance. The presentation is similar to the "top of the basilar syndrome", and early recognition should be prompted. We describe the case of a young female with this vessel variant who experienced a bilateral thalamic stroke. Magnetic resonance angiography demonstrated bilateral thalamic infarcts and a truncated artery of Percheron. Occlusion of the vessel was presumably due to embolism from a patent foramen ovale. Thrombolysis was performed, with incomplete symptom remission, cognitive impairment, and persistence of speech disorders. Early recognition and treatment of posterior circulation strokes is mandatory, and further investigation for underlying stroke etiologies is needed.

Keywords: cognitive impairment; paramedian thalamus territory; speech disorder; thalamus vascularization; vertical gaze palsy.

Figure 1

(A) Schematic representation of the affected thalamic nuclei in this case compared to an axial diffusion-weighted magnetic resonance image of the same patient. The black line limits the area of infarction in both paramedian regions. (B) Schematic representation of the artery of PA, T, BA, PCA, and PCOM. Abbreviations: PCOM, posterior communicating artery; BA, basilar artery; CM, centromedian; CL, central lateral; MD, dorsomedialis; Pf, parafascicularis; PA, percheron; PCA, posterior cerebral artery; Pv, paraventricular; T, thalamus.

Figure 2

Brain angio CT scan’s coronal view (A) and axial view (B). Note: Performed in the emergency department, showing no parenchymal lesions or main vessel obstruction: brain CT scan examination showed only a filling defect of the P1 segment of the left posterior cerebral artery (A).

Figure 3

(A) Brain CT scan axial view, performed after thrombolysis showing ischemic stroke in the paramedian territory of both thalami. (B) MRI axial view seq T2.