'Alien Hand' Syndrome
Turns Limbs Monstrous
By E.J. Mundell

NEW YORK (Reuters Health) -- Like victims in a horror film, patients with a rare syndrome known as 'alien hand' feel disassociated from one of their own hands, insisting that the hand is 'possessed' by a force outside their control.
The condition typically arises in the aftermath of brain surgery, stroke, or infection. Patients can feel sensation in the hand, but believe that it is not part of their body, and that they have no control over its movements. In some cases, ''alien hands can perform complex acts such as trying to tear clothes or undoing buttons,'' explain neurologist Dr. R. Inzelberg and colleagues at Hillel Yaffe Medical Center in Hadera, Israel.
Writing in the February issue of the Journal of Neurology, Neurosurgery, and Psychiatry, the Israeli team describes a case of 'alien hand' associated with a possible case of Creutzfeldt-Jakob disease (CJD), a degenerative brain disorder caused by infectious particles called prions.
The patient in question, a 70-year-old Argentinean man, underwent a swift neurological decline -- including hallucinations, memory dysfunction, behavior change and alien hand -- possibly caused by CJD. ``At times,'' the researchers report, ``(his) left arm would spontaneously rise in front of the patient during speaking.... He was unaware of these movements until they were brought to his attention.''
Isolated reports have linked alien hand with CJD in the past. In one case, ``the alien limb performed complex actions such as unbuttoning (the patient's) blouse and removing a hair pin.'' In another, a woman found herself ``powerless'' to prevent her hand from repeatedly touching her eyes and mouth.
According to the study authors, various types of brain injury appear to trigger distinct subtypes of alien hand. For example, in right-handed persons, injury to the corpus callosum -- a bundle of nerves connecting the two halves of the brain -- can give rise to ``purposeful'' movements of the left hand, while injury to the brain's frontal lobe can trigger ''grasping'' and other purposeful movements in the dominant (right) hand. In other cases, ``aimless movements of either hand'' occur in patients affected by injury to the brain's cerebral cortex. And the authors note that more complex alien hand movements -- such as unbuttoning or tearing of clothes -- are usually associated with brain tumors, aneurysm or stroke.
In every case, patients retain sensation of feeling in the affected hand or arm, but lose any sense of control over the renegade limb. ``They may struggle to stop the movements,'' Inzelberg told Reuters Health, ``restrain the limb, punish it, talk to it, personify or refer to it as a third person. The may even say that an evil spirit exists in the hand. In a sense the hand is the 'Other.'''
The study authors note that one common factor between the diseases associated with the phenomenon is that all these disorders involve several parts of the brain at once, suggesting that simultaneous damage to the parts of the brain that control movement may be responsible. In essence, Inzelberg explained, there is a ``disconnection between parts of the brain which are involved in motor (voluntary muscle) control.''
Unfortunately, there is currently no treatment for alien hand. According to the Israeli researcher, all patients can do to control the problem is to keep the hand ``occupied'' by having it hold an object.
Based on their findings, the investigators advise that Creutzfeldt-Jacob disease be added to the list of neurological disorders that prompt 'alien hand.' Inzelberg says future studies are planned ``to understand better the mechanisms involved in this rare condition.'' SOURCE: Journal of Neurology, Neurosurgery and Psychiatry 2000;68:103-104.


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