Alien Limb Phenomenon After Diffuse Corpus Callosum Ischemic Stroke

The alien limb is a phenomenon characterized by a cluster of clinical features wherein the limb behaves autonomously and as separated from a person's identity. We herein report a 36-year-old Indian female with multiple comorbidities who presented with recurrent episodes of limb-shaking transient ischemic attacks for 1 year, followed by left-sided hemiplegia. During recovering, the patient noticed a feeling that as if her left hand did not belong to herself and acted autonomously (alien limb phenomenon) along with visuospatial deficits. Magnetic resonance imaging of the brain revealed ischemic stroke diffusely involving corpus callosum. Magnetic resonance angiography was suggestive of compromised right-sided anterior circulation. This was corroborated by digital subtraction angiography that revealed reduced flow in right internal carotid artery. Diffuse infarction of the corpus callosum requires involvement of both the anterior and the posterior circulation. Due to the lack of clinical features suggestive of chronic internal carotid artery dissection, occlusive atherosclerotic disease of the anterior cerebral circulation associated with possible steal phenomenon from the posterior circulation was the most probable underlying mechanism for the callosal stroke. Steal phenomenon has been proposed as a compensatory mechanism in hemodynamically compromised ischemic parenchyma and it can explain the co-existence of anterior and posterior circulation strokes. This case also highlights how both anterior and posterior types of the alien limb phenomenon can co-exist in a background of vascular insult, resulting from intra-cranial atherosclerotic disease.