Imagine having a hand that has a will of its own. Never knowing what it’s going to do next. Turning on the light when you just turned it off, or worse, grasping a purse from a table you’re passing or even causing you physical harm. This rare medical condition is known as “alien hand syndrome”.
The condition is usually caused by a stroke or other brain damage, particularly in the areas of the corpus callosum (connecting the two cerebral hemispheres), or frontal or parietal lobes.
Although sufferers retain all sense of feeling in the “alien hand” (or leg), the hand acts autonomously, with reported movements ranging from involuntary touching the face to stuffing food in the mouth and even self inflicted choking.
As a consequence patients lose their sense of control over the limb and often describe feelings of dissociation. In addition, they may exhibit behaviors such as speaking to the hand or claiming its possessed.
According to Wikipedia, there is no known formal (primary) treatment for alien hand syndrome. However, the symptoms can be reduced and managed to some degree by keeping the alien hand occupied, for example by giving it an object to hold in its grasp.
Watch the video below to see a case of the alien hand syndrome: an operation left Karen Byrne with no control of her left hand.
Alien Hand Syndrome, by Allan Bellows
Photo via squatlo-rant
Assal, F, Schwartz, S, & Vuilleumier, P (2007). Moving With or Without Will: Functional Neural Correlates of Alien Hand Syndrome Annals of Neurology DOI: 10.1002/ana.21173