Pure posterior alien hand syndrome following a cerebrovascular lesion: Clinicoradiological correlates

Dear Editor, Alien hand syndrome (AHS) is a sensation of foreignness between the patient and one of his or her hands, where the affected hand is observed to perform autonomic purposive behaviors that are interpreted as spontaneous movements of the limb that have an alien origin.1 Recent studies have found that anatomical lesions leading to uncontrolled limb movement and a feeling of estrangement were predominantly located in the corpus callosum and/or supplementary motor area.2 In contrast to the well-known sequelae of anterior frontocallosal lesions, posterior AHS is a very rare clinical condition, and the pathophysiology underlying this phenomenon is still unclear.2 Object affordance theory suggest the role of the right parietal area and its connections with other areas in regulating object affordance primed by the environment. This theory further shows that exaggerated object affordance effects may lead to abnormal hand behaviors in AHS that are related to the balance of objectevoked automatic motor activation and the suppression of these automatically evoked responses.