Alien hand syndrome
Alien hand syndrome (anarchic hand or Dr. Strangelove syndrome) is an unusual neurological disorder in which one of the sufferer's hands seems to take on a life of its own. AHS is best documented in cases where a person has had the two hemispheres of their brain surgically separated, a procedure sometimes used to relieve the symptoms of extreme cases of epilepsy. It also occurs in some cases after other brain surgery, strokes, or infections.
Symptoms
An Alien Hand sufferer can feel normal sensation in the hand, but believes that the hand, while still being a part of their body, behaves in a manner that is totally distinct from themselves. They feel that they have no control over the movements of their alien hand. Alien hands can perform complex acts such as undoing buttons or removing clothing. Sometimes the sufferer will not be aware of what the hand is doing until it is brought to his or her attention. Sufferers of Alien Hand will often personify the rogue limb, for example believing it "possessed" by some intelligent or alien spirit, and may fight or punish it in an attempt to control it. There is a clear distinction between the behaviors of the two hands in which the affected hand is viewed as "wayward" and sometimes "disobedient" and generally out of the realm of their own voluntary control, while the unaffected hand is under normal volitional control. At times, particularly in patients who have sustained damage to the corpus callosum that connects the two cerebral hemispheres, the hands appear to be acting in opposition to each other. For example, one patient was observed to be putting a cigarette into their mouth with their intact hand (in this case, their right dominant hand), following which their alien opposite nondominant left hand then came up to remove the cigarette from the mouth and toss it away before it could be lit by the controlled dominant right hand. The patient then surmised that "I guess 'he' doesn't want me to smoke that cigarette". This type of problem has been termed "intermanual conflict" or "diagonistic apraxia". This condition has been thought to provide a fascinating window into the nature of human consciousness as it relates to voluntary action and conscious volition (psychology), as well as the general nature of agency (human).
Causes and treatment
There are several distinct subtypes of Alien Hand that appear to be associated with specific types of triggering brain injury. Damage to the corpus callosum can give rise to "purposeful" actions in the sufferer's non-dominant hand (a right-handed sufferer's left hand will turn alien, and the right hand will turn alien in the left-handed) as well as a problem termed "intermanual conflict" in which the two hands appear to be directed at opposing purposes, whereas unilateral injury to the brain's frontal lobe can trigger reaching, grasping and other purposeful movements in the contralateral hand. With frontal lobe injury, these movements are often exploratory reaching movements in which external objects are frequently grasped and utilized functionally, without the simultaneous perception on the part of the patient that they are "in control" of these movements. Once an object is maintained in the grasp of the "frontal" form of alien hand, the patient often has difficulty with voluntarily releasing the object from grasp and can sometimes be seen to be peeling the fingers of the hand back off the grasped object using the opposite controlled hand to enable the release of the grasped object. A distinct "posterior" form of alien hand syndrome is associated with damage to the parietal and occipital regions of the brain. The movements in this situation tend to be more likely to withdraw the palmar surface of the hand away from environmental contact rather than reaching out to grasp onto objects to produce palmar tactile stimulation, as is most often seen in the frontal form of the condition. Alien movements in the posterior form of the syndrome also tend to be less coordinated and show a coarse ataxic motion that is generally not observed in the frontal form of the condition. The 'alien' movements, however, remain purposeful and goal-directed, a point which clearly differentiates these movements from other forms of involuntary limb movement (eg. chorea, or myoclonus).
Patients thus will often indicate that the apparently purposeful movements of the alien hand are "wayward" or "disobedient", in that they are not being generated through the exertion of their own voluntary will or directed toward goals that have been consciously produced, but, instead, the alien hand appears to behave independent of conscious will, effectively "on its own". The alien hand may even engage in socially inappropriate behavior in a public venue causing significant embarrassment and distress. Patients may react with dismay and concern at the ability of the hand to perform purposeful actions that are independent of their own sense of control over the movement, a phenomenon termed "auto-criticism". Alternatively, they may attribute the forces initiating and controlling these purposeful movements to some external being that is somehow "alien" to their self-perceived being. For example, a particularly religious woman with alien hand syndrome, when asked who or what was actually controlling the alien movements of her hand, replied that "God must be doing all of that". Some patients choose to "personify" the hand and dissociate themselves from the behavior of the hand by giving it a proper name and attributing to it a separate and distinct personality and personhood. They may choose to "hold back" these unwanted "alien" movements and behaviors by grasping and constraining the "wayward" hand with the controlled contralateral hand, an action that has been termed "self-restriction" or "self-grasping". Injuries to the cerebral cortex can give rise to aimless movements of either hand, and more complex alien hand movements are usually associated with brain tumors, aneurysm or stroke. Such alien movements and behaviors can also be seen in progressive degenerative diseases of the central nervous system, such as Creutzfeldt-Jakob Disease, or corticobasilar degeneration.
It is theorized that Alien Hand Syndrome results when disconnection occurs between different parts of the brain that are engaged in different aspects of the control of bodily movement. As a result, different regions of the brain are able to command bodily movements without simultaneously generating a conscious feeling of self-control over these movements. There is thus a dissociation between the process associated with the actual execution of the physical movements of the limb and the process that produces an internal sense of voluntary control over the movements, thus creating the internal conscious sensation that the movements are being internally initiated, controlled and produced. This most likely involves an abnormality in the brain mechanism that differentiates between "re-afference" (ie. the return of kinesthetic sensation from the self-generated limb movement) and "ex-afference" (ie. kinesthetic sensation generated from an externally-produced limb movement). There is no known treatment for Alien Hand Syndrome at this time though the symptoms can be reduced by keeping the alien hand occupied and involved in a task, for example by giving it an object to hold. For example, one patient with the "frontal" form of alien hand who would reach out to grasp onto different objects (eg door handles) as they were walking, was given a cane to hold in the alien hand while walking. With the cane firmly in the grasp of the alien hand, it would generally not release the grasp of the cane in order to reach out to grasp onto a different object. Thus, different strategies can be employed to reduce the interference of the alien hand on the ongoing coherent controlled actions of the patient. Furthermore, in the presence of unilateral damage to a single cerebral hemisphere, there is generally a gradual reduction in the frequency of alien behaviors observed over time and a gradual restoration of voluntary control over the affected hand, suggesting that plasticity in the bihemispheric and subcortical brain systems involved in voluntary movement production can serve to re-establish the connection between the executive production process and the internal self-generation and registration process. In another approach, the patient is trained to perform a specific task, such as moving the alien hand to contact a specific object or environmental target, which is a movement that they can learn to generate voluntarily in order to override the alien behavior.
Cultural references
- In the movie Mad Love (1935) starring Peter Lorre, a pianist's hands are replaced with those of a murderer and take on a life of their own.
- The character Dr. Strangelove in the movie Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb suffers from the syndrome. His hand seems to act in a more complex manner, linked with his unconscious feelings (e.g. reacting when he speaks about the Nazi party or eugenics).
- The character Ash in the Evil Dead series of movies is forced to cut his hand off with a chainsaw because it has been (quite literally) possessed by evil, and has taken on a life of its own.
- Mentioned in the Elliott Smith documentary film Strange Parallel as it relates to Elliott's paranoia of futuristic "robot hands" that control themselves.
- In Metal Gear Solid 2: Sons of Liberty, virtuoso gunman Revolver Ocelot suffers from an alien arm controlled by the dispossessed personality of its original owner, Liquid Snake.
- Anton Tobias's (Devon Sawa) hand is possessed in the movie Idle Hands (1999).
- In Clive Barker's short story The Body Politic, the hands of several people start a rebellion against their human hosts which leads to a full scale massacre when more hands join this revolution.
- In Ray Bradbury's short story Fever Dream, the main character contracts a disease which slowly takes over the use of his body, beginning with his right hand.
- In Angel's episode Dead End, Lindsey McDonald's new hand remains psychically linked to its original owner and constantly writes "kill" because the owner wants to be killed.
- In The Shadow of the Torturer by Gene Wolfe the Chatelaine Thecla is sentenced to punishment by a device known as "the Revolutionary", the effect of which is to make her hands take on a seeming life of their own and cause self-injury.
- In the movies and television series depicting the adventures of the "The Addams Family", "Thing (Addams Family)", an invention of originator Charles Addams, is a "disembodied" hand which takes on a life and personality of its own independent of the control of any apparent central nervous system directing its actions.
- See also the comedic potential of dissociation concepts and the invasion of 'alien' control over directed behavior in Steve Martin's work in The Man with Two Brains, and All of Me. One might consider Mr. Martin's background as a philosophy major as preparation for these roles.