Is your hand an alien?

No, not like ET. [via]

Is it weird that I have a favourite syndrome? I really don't wish to make light of what I'm sure is a difficult situation, but I truly find Alien Hand Syndrome (AHS) fascinating. It also probably doesn't help that there are documentaries about it that have terrible/amusing re-enactment scenes (I love dodgy re-enactments). So what is it and how does it happen?

 

I should note this is really quite rare; according to this BBC article in 2000 there were at that time approx 40 people with an Alien Hand. Basically, although it can occur due to brain damage (and possibly even a prion disease), it is most well known for occuring following a surgical procedure called a corpus callosotomy. Some people have seizures that are so severe that medication does not help. As a last resort (though to be honest I'm not sure how often this happens now), surgeons will sever the two brain hemispheres at the corpus callosum - the part of the brain that allows the two hemispheres to communicate with each other. Doing this means a seizure will only be localised to one hemisphere and the seizure can no longer spread to the entire brain. This means the effects of the seizure will be far less debilitating for the sufferer. However this often brings with it a curious side effect: sometimes parts of one side of the body will at times no longer seem to be under the person's control. As the left side of the brain generally contains most of the language functions, and the right side does not, when they are separated it is hard to consciously understand what occurs on that side - hence the behaviour of the left hand seems inexplicable and disobedient (yes I said left hand - this is because the hemispheres of the brain control the opposite side of the body). As such their hand appears 'alien' to them and does all sorts of bizarre behaviours. 

No, not like Thing either.

Anecdotes include a person with one hand trying to get dressed and doing up buttons, with the alien hand simultaneously trying to undress them; one hand trying to put a cigarette in their mouth and light it, while the alien hand slaps it away "I guess he doesn't want me to smoke!"; and enter the terrible re-enactment - the alien hand trying to drive the person off the road (at ~5 min of this youtube clip of an AHS documentary, though consider watching the whole thing, pretty interesting). 

What can be done about this 'wayward' hand? In case of brain injury, it is possible that with time and recovery it will gradually come back under the control of the person. However in other cases where the connection has been permanently severed, this may be less likely. There has also been a study that tried antipsychotic medication and botox injections to control 'limb leviation' frequency in the alien hand; however the antipsychotic was found to cause a psychotic episode (yes strangely that can happen), and I'm a bit unsure what I think of the botox idea - isn't it just paralysing the arm? As such management techniques may be better: for example, occupying the hand with other tasks such as grasping an object.

I remember seeing some of the abovementioned documentary when I was younger, and it further cemented my love for psychology and neuroscience. Also with AHS comes some intriguing philosophical questions: Does the less dominant right hemisphere actually have a different (potentially more primal) personality that is usually under the control of the more rational left hemisphere? Does AHS refute free will /are we really in control of our own actions? Do you love poorly-acted re-enactments as much as I do? Ok the last question isn't so philosophical but important nevertheless. 

P.S. If you're interested in more information please feel free to ask me, as I obviously love talking about it! This 'stuff you should know' clip on AHS is cool too. 

P.P.S. For no real reason I can think of except all the cool kids are doing it, I now also have a facebook page. So please 'like' it for updates and special extras*!

*content may not be special or extra.