Health Talk: Alien hand syndrome

The Halloween season is the time for psycho-thrillers and horror movies. However, fans of such movies should consider delving into some medical literature to get the best scary stories.

In one such medical case, a 68-year-old woman, who was hospitalized after extensive brain damage and dementia, claimed that a ghost was pulling her hand. She told the medical personnel that she was afraid her hand would harm them. Her fear proved to be justified, as she later tried to strangle one of the examiners with her left hand. But that is not the end of the story; she later tried to strangle herself by wrapping the call button cord around her neck with her left hand.
This case, reported in an article in the July 2008 issue of The Consultant, is an example of a rather well-documented disorder known as alien hand syndrome.

Patients suffering from this disorder have no voluntary control over one of their hands. The hand may reach out and grab objects or even perform complicated tasks like buttoning up clothing or strangling oneself without the patient meaning to do so.

Although this phenomenon is not particularly hazardous to the patients’ health, it does cause a lot mental frustration. Some patients even go as far as associating a different personality, and sometimes even a different name, with the hand The seemingly supernatural disorder is caused by a few broken connections in the brain. Brain damage can be caused by a variety of factors including accidents, strokes, and brain hemorrhages. One of the causes of alien hand syndrome is damage to the corpus callosum of the brain. The corpus callosum connects the two halves of the brain and helps the two halves communicate with one another.

Damage to the corpus callosum therefore disconnects the two halves of the brain and generally disrupts communication between the two sides of the body. In such patients, the dominant hand can be controlled voluntarily, but the other hand shows involuntary movements.
What is striking about patients with corpus callosum damage is that the two hands tend to perform opposing actions. For example, if one hand voluntarily picks up an object, the other hand will involuntarily try to put that object back down. The frontal cortex, which is the foremost part of the upper layer of thebrain, also plays a role in the alien hand syndrome. Patients who have the corpus callosum and regions of the frontal cortex damaged exhibit obsessive grasping behaviors. In many cases, patients have to forcefully pry open the fingers of the alien hand with their good hand to release the objects.

Damage to the posterior regions of the brain show yet another set of symptoms. The alien hands in such cases tend to stray away from anything in the environment and show uncoordinated movements.

Although damage to these areas of the brain has been linked to the disorder, the reason why the damage causes the disorder is not known yet. Studies have suggested that the damaged areas may play a role in voluntary movements of the body, but exact causes still remain a mystery.

As of now, there isn’t any treatment for this disorder, but in many cases, the symptoms seem to diminish if the alien hand is kept occupied with some task.

For patients with the obsessive grasping disorder, if the hand is made to hold an object like a cane at all times, it no longer attempts to grasp other objects.

However, patients still have to cope with the perpetual loss of one hand as the alien hand cannot be used to perform any meaningful tasks.

Researchers, however, view the disorder as an interesting tool with which they can further explore the brain.