Alien hand syndrome in left posterior stroke.

Alien hand syndrome is a rare neurological disorder characterized by involuntary and uncontrollable motor behaviour, usually of an arm or hand. The patient perceives the affected limb as alien, and may personify it. The case of a 61-year-old right-handed woman who developed right posterior AHS after ischaemic stroke in the left posterior cerebral artery territory is reported. Neuroimaging studies disclosed no frontal or parietal involvement, while a posterior thalamic lesion was detected. A possible role of the thalamus in the genesis of AHS is discussed.