Bilateral Paramedian Thalamic Infarction

Rarely, both paramedian thalami receive arterial blood flow from a single unilateral vessel arising from the first segment of 1 posterior cerebral artery. This artery has received the name of artery of Percheron (AP). There is no consensus regarding the true prevalence of this anatomical variant. Bilateral paramedian thalamic infarcts are uncommon (0.1% to 2% of ischemic strokes). The main cause is the occlusion of the AP due to cardioembolism. Diffusion-weighted magnetic resonance imaging demonstrates the lesion in the acute setting.

From September 2004 to October 2011, we identified 5 patients who had bilateral paramedian thalamic infarcts. We describe clinical findings and diagnostic imaging patterns observed in these cases and review the literature.

Three men and 2 women with bilateral paramedian thalamic infarction probably due to occlusion of AP are described. Mean age at presentation was 58±24 years. Magnetic resonance imaging showed the lesion in all patients. Four patients presented loss of consciousness as initial symptom. Only 1 patient evidenced mesencephalic extension of the infarct on magnetic resonance imaging, although 4 presented abnormal ocular signs. No patients received intravenous thrombolisis because of delayed diagnosis. All patients were discharged home. A 90-year-old woman recovered completely and the other 4 subjects persisted with cognitive symptoms and gaze abnormalities.

Clinical presentation and imaging patterns described in this group of patients were similar to published data. High level of suspicion based on clinical and imaging findings is essential for early diagnosis of this rare condition. None of our patients had an early diagnosis of acute ischemic stroke and received proper thrombolytic treatment.