Researchers Attempt to Pinpoint ‘Alien Hand Syndrome’ : Neurology: Patients report losing control over one of their hands. Doctors say disorder may hold key to interaction of brain halves.

No one who has seen the film classic “Dr. Strangelove” will forget the inspired lunacy when the left arm of Peter Sellers, who played the crazed doctor, takes on a life of its own, flipping Nazi salutes and attempting to strangle the wheelchair-bound defense adviser while Sellers struggles to control the demented digits with his other hand.

As far-fetched as that portrayal may seem, there is apparently a scientific basis for it.

An estimated several thousand Americans may suffer from a little-known neurological disorder called “alien hand syndrome,” in which their left hands quite literally do not know what their right hands are doing, according to neurologist Rachelle Doody of Baylor University in Houston. Doody discussed the syndrome Wednesday at a Boston meeting of the American Academy of Neurology.

In the least severe forms of the syndrome, one of the patient’s hands may flop aimlessly out of control. In more severe cases, it may try to do the same things the opposite hand is doing or attempt to counter them. In the worst cases, the hand may become aggressive--pinching, slapping or punching the patient--and in at least one recorded case, even trying to strangle its owner.

The syndrome appears to be caused by damage to certain areas of the brain and is often temporary, disappearing a few months after the damage occurs. It can be reproduced in animals by damaging the same areas of the brain.

No treatment for the syndrome exists, but animal studies suggest that it may be possible to develop surgical techniques to minimize the symptoms, Doody said.

Meanwhile, neurologists are studying the bizarre syndrome in an effort to gain a better understanding of how our two-sided brain balances its control of the two sides of the body. Normally, the left half of the brain controls the right side of the body and vice versa.

The disorder can be quite frightening for patients, said neurologist Ramone Leiguarda of the Institute for Neurological Research in Buenos Aires. Leiguarda recounted a written description of the disorder by what he termed a “typical patient.”

“I was traveling on a bus,” the patient wrote, “when I noticed a hand approaching me from the right from behind and trying to catch me. After grasping my trouser leg, the hand would not release it. At first I thought somebody was robbing me, but then I realized it was my own right hand. . . . I couldn’t sleep at all that night because I was terrified my abnormal hand would assault me while I was sleeping.”

Usually, the symptoms are not so dramatic, but they are disconcerting. In all cases, Doody said, the affected limb feels foreign or alien to the patient, as if it is not part of their body.

It is not that the arm actually has a mind of its own, said UCLA neurologist Charles Markham. A damaged brain, he said, can cause parts of the body to be controlled “by a part of the mind not directly accessible to the conscious” so it appears the limb is acting independently.

Because the limb does seem to have a mind of its own, patients often personify it, giving it a unique identity. “One woman called her arm Baby Joseph, and thought of it as a mischievous baby,” Doody said.

Often, the affected hand will mirror what the normal hand is doing. “If the right hand goes to do something, the left hand tries to beat it,” Doody said. This can make it difficult to dial a telephone or retrieve something from a purse.

More often, the affected hand will try to do the opposite of what the normal hand is doing, Leiguarda said. “If a person is trying to button a shirt with one hand, the other hand will follow along and undo the buttons,” he said. “If one hand opens a book, the other will shut it. If one hand pulls up trousers, the other will pull them down.”

“Often a patient will sit on the hand, but eventually it gets loose and starts doing everything again,” Doody said.

Neurologists are not sure of the phenomenon’s precise mechanism, but it can be caused by strokes, degenerative diseases or anything that causes damage to certain areas of the brain, especially the thalamus, which coordinates sensory perceptions, and the corpus callosum, which connects the two spheres of the brain.

Leiguarda said the syndrome is a frequent complication when surgery is performed on the corpus callosum to alleviate severe epileptic symptoms.

Usually the phenomenon disappears in a few weeks to a few months after the brain reorganizes itself to bypass the damage, Leiguarda said.

Studies correlating the extent of damage in the rare disorder with the various symptoms, Doody said, “give us information about how different parts of the brain work together to achieve a goal.”

Doody has never seen “Dr. Strangelove” and Leiguarda has never even heard of it. Leiguarda noted that he had been searching through history and mythology without success to find a name for the disorder. “Perhaps the ‘Strangelove syndrome’ is not such a bad name,” he said.