Bilateral Paramedian Thalamic Artery Infarcts: Report of 10 Cases

The paramedian thalamic arteries can arise as a pair from each P1 of the posterior cerebral artery, but they may also arise equally from a common trunk off one P1, thus supplying thalamus bilaterally. Such a common trunk is called the artery of Percheron and supplies the mesial aspects of both thalami and the rostral midbrain. This is a retrospective review of 1253 consecutive patients with ischemic stroke enrolled in a stroke registry within an 8-year period (January 2001-December 2008). All were evaluated with detailed clinical and neuropsychological evaluation, magnetic resonance imaging (MRI), blood studies, electrocardiogram, and transthoracic echocardiography. All standard risk factors were recorded in these patients. Ten patients (0.7%) in this series presented with a first-ever thalamic stroke demonstrating bilateral paramedian thalamic lesions on MRI. The main cause of bilateral paramedian thalamic infarctions was small artery disease (60%), followed by cardioembolism (40%). A well-defined clinical picture is shown in bilateral paramedian thalamic artery infarcts. These patients had disorder's consisting of consciousness, memory dysfunctions, various types of vertical gaze paresis, and psychological changes. Although neurologic deficits and hypersomnia recovered to large extent in patients with paramedian thalamic infarcts, cognitive deficits that were mainly linked with bilateral and left-sided lesions often persisted. Vertical gaze paresis tended to improve and never seriously disturbed the patient's activities. We believe that these kinds of strokes have been commonly overlooked, especially without widespread use of MRI.