There is a very rare, disturbing and interesting medical condition called alien hand syndrome (AHS). An individual with this neurological disorder has full sensation in the rogue hand, but is unable to control its movements and does not feel that it is a part of their body. The hand becomes personified, as if it has a will of its own, and its owner will usually deny ownership of the limb.
Though AHS was first identified in 1908, it was not clearly defined until 1972. Depending on the cause of the injury, the movements may be random or purposeful, and may affect the dominant or non-dominant hand. The symptoms are brought on by an injury to the brain, such as head trauma, stroke, tumour, or infection. It can also be a side effect of a certain kind of brain surgery where the patient has the two hemispheres of the brain separated to relieve severe epilepsy.
If the AHS is caused by separation of the corpus callosum (the area of the brain that connects the two halves of the brain) by surgery or injury, the movements are usually complex purposeful behaviour, such as compulsive manipulation of tools, undoing buttons, or tearing clothes. For example, a right-handed person is left-hemisphere-dominant, thus their left hand (controlled by the right hemisphere) will become “alien”. Sometimes the sufferer is completely unaware of what the hand is doing until it is brought to his or her attention, or until they happen to see it themselves.
Strangely, many of the alien hand’s actions are the complete opposite of what the person is doing with the other hand. For example, if they start packing a suitcase, the alien hand will unpack it. It is believed that one half of the brain (usually the right brain) is unaware of why the other hand is doing something (due to the lack of connection between the two hemispheres) and so proceeds to “correct” it. There are also reports of the alien hand attacking the patient by hitting them or even trying to strangle them in their sleep.
There is currently no treatment for alien hand syndrome, but the symptoms can often be relieved by giving the rogue hand an object to manipulate, to keep it occupied. One patient whose alien hand had a compulsion of holding on to door handles or other objects to stop the man from walking was given a cane. The alien hand would grab on to the cane and not interfere with the patient’s walking.
There is currently no treatment for alien hand syndrome, but the symptoms can often be relieved by giving the rogue hand an object to manipulate to keep it occupied. One patient whose alien hand had a compulsion of holding on to door handles or other objects to stop the man from walking was given a cane. The alien hand would grab on to the cane and not interfere with the patient’s walking.
Although it is a distressing condition, some patients learn to live with the disease. For instance, when one patient’s alien hand kept throwing away the cigarette her dominant hand put in her mouth, she shrugged and said: “I guess ‘he’ doesn’t want me to smoke that”. Perhaps the alien hand is simply a way for the subconscious mind to physically act on the conscious mind.