Neurological Conditions

What causes alien hand syndrome?
Answered by Science Channel
  • Science Channel

    Science Channel

  1. One of the more classic comedic moments on screen occurs when Peter Sellers' character in "Dr. Strangelove," continually fights with his own arm to stop it from repeatedly attempting to give a Nazi salute. His right arm seems to have a mind of its own, with sinister intentions that he can't control. The medical condition depicted comedically by Sellers is a rare neurological disorder called alien hand syndrome -- and naturally, people who have it don't find it funny. In fact, they often experience psychological problems and embarrassment and are occasionally harmed by the limb's actions.

    There are other disorders that can cause movements in the hands and other limbs. A person can have seizure or disorders such as chorea or dystonia. But those movements tend to be more random and purposeless. With alien hand syndrome, the arm appears to move intentionally [source: MSNBC].

    The syndrome first was reported in 1908 by German neurologist and psychologist Kurt Goldstein. It is fitting that Goldstein had both a psychology and neurology background, because the study of alien hand syndrome still is rooted in both. Aside from the psychological effects having the strange disorder can cause, there are unanswered questions about whether alien hand syndrome has a complicated relationship to free will [source: Cheshire].

    It has long been believed that alien hand syndrome results from damage to the corpus callosum, the part of the brain responsible for coordinating messages between the left and right hemispheres. In this unusual situation, the lack of interhemispheric communication causes one hand to function normally under full control of the affected person, but the other hand to act on its own, sometimes in an annoying or even harmful way.

    In 2007, research from Switzerland using functional magnetic resonance imaging reported that neural activity in the primary motor cortex controls the type of unconscious motor movement patients with alien hand syndrome experience [source: Science Daily]. The research is one step toward determining how the syndrome is caused, how to treat it and even how to improve our understanding of voluntary and involuntary motor movement and neurological processes. To date, there is no known cure for alien hand syndrome.


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