Bilateral Thalamic Infarction by Percheron Artery Occlusion Infarto Talâmico Bilateral por Oclusão da Artéria de Percheron Walter J. Fagundes-Pereyra 1 , Alexandre Neves Furtado 2 Filipe Machado Barcelos 2 Jovarci Motta 2 1 Médico do Departamento de Neurocirurgia do Hospital Estadual Dr. Dório Silva. Professor do Departamento de Clínica Cirúrgica da Universidade Federal do Espírito Santo (UFES). 2 Acadêmico do curso de Medicina da Universidade Federal do Espírito Santo (UFES). ABSTRACT Objective: The artery of Percheron is an uncommon single trunk variant of the thalamoperforating arteries that supplies the paramedian thalamic territory bilaterally and the rostral midbrain. Four cases of artery of Percheron (PA) occlusion with bilateral paramedian thalamic infarctions are reported, considering aspects of its clinical and radiological presentation, as well its prognosis. Methods: Four patients with infarcts due to PA occlusion were diagnosed. The data for the study were retrospectively obtained from the medical records of patients. Results: Four patients with PA infarctions were diagnosed. All patients have presented a symmetrical bilateral paramedian thalamus infarction, and two of them also presented midbrain involvement, with abnormal images on MRi and CTs. Clinical presentations have included sudden onset of bilateral palpebral ptosis, headache, ophthalmoplegia, aphasia, prostration, confabulation, mental confusion and ataxia. Conclusion: Although rare, occlusion of artery of Percheron should be part of the differential diagnosis when symmetrical bilateral paramedian thalamic and mesencephalic lesions occur. Key words: Cerebral Arterial Diseases; Stroke; Brain Infarction; Cerebral Infarction; Infarction, Posterior Cerebral Artery RESUMO Objetivo: A artéria de Percheron é uma variante rara das artérias tálamoperfurantes, representada por um tronco único que irriga o território talâmico paramediano bilateral e o mesencéfalo rostral. Quatro casos de oclusão da artéria de Percheron com infartos talâmicos paramedianos bilaterais são relatados, considerando aspectos de sua apresentação clínica e radiológica, bem como seu prognóstico. Métodos: Quatro pacientes com infartos decorrentes da oclusão da artéria de Percheron foram diagnosticados. Os dados do estudo foram obtidos dos respectivos prontuários. Resultados: Quatro pacientes com infartos decorrentes da oclusão da artéria de Percheron foram diagnosticados. Todos os pacientes apresentaram infarto talâmico paramediano bilateral simétrico, e dois deles também apresentaram envolvimento mesencefálico, com imagens anormais na ressonância magnética e tomografas. Manifestações clínicas incluem início súbito de ptose palpebral bilateral, dor de cabeça, oftalmoplegia, afasia, prostração, confabulação, confusão mental e ataxia. Conclusão: Apesar de rara, a oclusão da artéria de Percheron deve fazer parte do diagnóstico diferencial quando lesões talâmicas paramedianas bilaterais simétricas e mesencefálicas ocorrerem. Palavras-chave: Doenças Arteriais Cerebrais; Acidente Vascular Cerebral; Infarto Encefálico; Infarto Cerebral; Infarto da Artéria Cerebral Posterior Received June 30, 2014. Accepted Dec 12, 2014 I ntroduction The artery of Percheron (PA) is an uncommon anatomic variant of the thalamoperforating arteries, represented by a single trunk that arises from the P1 segment of one of the posterior cerebral arteries (PCA). This artery supplies the paramedian thalamic territory bilaterally and the rostral midbrain 5,11 . When it is occluded, the thalamic infarcts are always bilateral and medial, with or without mesencephalic involvement 3,8 . We report four cases of PA occlusion with bilateral paramedian thalamic infarctions, considering aspects of its clinical and radiological presentation, as well its prognosis and treatment. Methods The data for the study were retrospectively obtained from the analysis and systematic review of the medical records of patients. All of them occurred between 2010 and 2012, and had Magnetic Resonance imaging (MRi) (including FLAIR 22 Original WJ Fagundes-Pereyra, AN Furtado, FM Barcelos, J Motta. - Bilateral Thalamic Infarction by Percheron Artery Occlusion J Bras Neurocirurg 25 (1): 20 - 23, 2014