The cause of alien hand syndrome is not yet known, though it may be brought on by brain surgery.
Think for a moment about how you move your limbs. You don’t really have to think about it, but you definitely control it, right?
Now imagine if you didn’t. Imagine if your limbs suddenly started to move themselves. Imagine if they even began to attack you. That might sound like a bad horror movie, but for people with alien hand syndrome, it’s a disturbing reality.
Alien hand syndrome is a condition where the limbs move without the person they’re attached to trying to move them. As the name suggests, it’s usually the hands that are affected, and for reasons we don’t understand, it’s usually the left hand.
The hand might flutter around, grab things, or even attack the person affected. There have even been cases where alien hands will slap or try to strangle the person it belongs to.
Usually, the person with the condition doesn’t realize the hand is doing it until they actually see it move, or feel it touch something. Sometimes, they even have to physically restrain the alien hand with the “good” hand.
That lack of connection between the hand and the rest of the body often leads to people with the condition seeing the hand as having its own personality. Sometimes, they’ll even give it a name. It’s hard not to personify a limb at least a little bit when it seems to have a mind of its own.
Often, the alien hand doesn’t want to cooperate with the person it belongs to. Many patients with the condition display something called “intermanual conflict.” Essentially, whatever the patient tries to do, the alien hand tries to stop.
For instance, if they put something in their mouth, the alien hand will pull it out. In other cases, they’ll be buttoning up a shirt with one hand while the other quickly unbuttons it.
But it’s not just hands that are affected. The condition can also affect other limbs, like in the case of a woman in New Jersey with an alien leg. In her case, the leg would suddenly want to change directions while walking, leaving the woman constantly turning in circles.
We don’t know what causes alien hand syndrome, but it obviously has something to do with the brain. One clue might be the fact that the condition is most common in people who have had a surgical procedure to separate the two halves of the brain.
The procedure, known as a corpus callosotomy, is usually done in cases of extreme epilepsy and involves physically severing the fibers that hold the brain together. This stops the electrical signals in the brain that cause epilepsy, but it may also interfere with the way the brain sends signals to move the limbs, which could be the cause of alien hand syndrome.
However, any condition that damages the connections in the brain that control movement can lead to the condition. Alien hand syndrome has been seen in cases of Alzheimer’s, stroke, and Crutzfeldt-Jakob disease, and it can last anywhere from several months to several years.
The good news is that alien hand syndrome is very rare. But, you may want to keep a close eye on that hand just in case.