This article possibly contains original research. (October 2015) |
Alien hand syndrome | |
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Other names | AHS; alien limb syndrome; ALS; Dr. Strangelove syndrome |
Specialty | Psychiatry, Neurology |
Alien hand syndrome (AHS) or Dr. Strangelove syndrome[1] is a category of conditions in which a person experiences their limbs acting seemingly on their own, without conscious control over the actions.[2] There are a variety of clinical conditions that fall under this category, most commonly affecting the left hand.[3] There are many similar terms for the various forms of the condition, but they are often used inappropriately.[4] The affected person may sometimes reach for objects and manipulate them without wanting to do so, even to the point of having to use the controllable hand to restrain the alien hand.[5] The occurrence of alien hand syndrome can be usefully conceptualized as a phenomenon reflecting a functional "disentanglement" between thought and action.
Alien hand syndrome is best documented in cases where a person has had the two hemispheres of their brain surgically separated,[6] a procedure sometimes used to relieve the symptoms of extreme cases of epilepsy and epileptic psychosis, e.g., temporal lobe epilepsy. It also occurs in some cases after brain surgery, stroke, infection, tumor, aneurysm, migraine and specific degenerative brain conditions such as Alzheimer's disease, corticobasal degeneration[7] and Creutzfeldt–Jakob disease.[8] Other areas of the brain that are associated with alien hand syndrome are the frontal, occipital, and parietal lobes.[9][10][unreliable medical source?][8]
The alien hand syndrome is a deeply puzzling phenomenon in which brain-damaged patients experience their limb performing seemingly purposeful acts without their intention. Furthermore, the limb may interfere with the actions of their normal limb.
The term "alien hand" refers to a variety of clinical conditions whose common characteristic is the uncontrolled behavior or the feeling of strangeness of one extremity, most commonly the left hand.
A large variety of complex, abnormal, involuntary motor behaviors have been described following callosal lesions which may or may not be accompanied by hemispheric damage, especially in the frontal medial region. Although the different terminologies used to describe these movements attempt to address their clinical specificity, there is a noticeable nosological confusion in the literature which results in assigning similar names, often inappropriate, to diverse phenomena and vice versa. One example of such confusion is the group of syndromes labeled as "alien hand"[1], "anarchic hand" [2, 3], "way-ward hand" [4, 5], "intermanual conflict"[6] and "diagonistic dyspraxia" [7, 8].