Our brain is made up of two hemispheres connected by a bundle of nerve fibers that make up the corpus callosum. Thanks to this structure, the two hemispheres can exchange information and, with the action of other areas of the brain, we can be aware of our own body.
However, when this structure breaks down or is damaged a strange disorder known as alien hand syndrome may appear whereby the person is unable to control the movements of their own arm and hand which may be felt as strangers or even possessed.
What is someone else’s hand syndrome?
Also called “strange hand syndrome”, “foreign hand syndrome” or “Dr. Strangelove syndrome”, this strange disorder of neurological origin is distinguished by provoking the person suffering from it. all kinds of involuntary and uncontrolled movements in one of the upper limbs.
In addition, another peculiarity of the syndrome of the other hand is the feeling of strangeness that the person feels towards this member. In other words, the patient experiences it personification of the arm and the hand, which seem to him to have a life of their own.
The first time this syndrome was described was in 1908. The famous German physician Kurt Goldstein discovered these strange symptoms in patients who had undergone a commissurotomy. This procedure involves making an incision in the corpus callosum and was typical of treatments for very severe epilepsy, in order to prevent these attacks from spreading from one cerebral hemisphere to another.
There are two different types of extraterrestrial hand syndrome, which differ based on the causes and anatomical correlates of this syndrome.
1. Acute variant of the syndrome
One of the ways the syndrome manifests itself is the acute variant, which is due to damage to the corpus callosum that they cause temporary changes to the additional motor zone. It is hypothesized that this damage is due to hemispherical retraction during comisurotomy.
This acute variant is characterized by more intense and exaggerated movements, but of short duration.
2. Chronic variant
The second form of other hand syndrome is the chronic variant. The cause is due to damage to the corpus callosum, as well as damage to the additional motor zone, located in the medial frontal lobe.
What symptoms appear?
The clinical picture of other hand syndrome has two main symptoms. These symptoms are:
Sensation of dissociation of the affected limb. The person strongly believes that this arm is not part of their body and that, therefore, he cannot exercise any control over his movements. However, tactile sensitivity is preserved so that although the person cannot control it, they can feel whatever is happening to their member.
Lack of movement control
the patient he is not aware of the actions of the affected arm and hand. In other words, the person does not notice that the limb is making any movement, however complicated or exaggerated it may be.
In many cases, the movements made by the limb considered to be foreign interfere with the movements or actions performed by the healthy limb. In addition, this neurological disorder dissociate intention from action so that the impulses of the foreign hand are totally opposite to those of the healthy hand.
After observation of the case, it was detected that these “extraterrestrial members” they tend to react in response to nearby stimuli as striking objects that are within their reach. For this reason, it is hypothesized that the behavior of these members is guided by contextual stimuli.
The intensity of symptoms may fluctuate. In very stressful or very anxious situationsThe clinical picture of other hand syndrome tends to increase in both quantity and intensity.
Ultimately, these symptoms can lead to a large number of psychological and emotional side effects. This associated symptomatology can range from confusion and anxiety to fear experimentation and fear or panic attack. However, the psychological consequences can vary greatly from patient to patient as many of them learn to live with this type of disorder.
What are the causes?
As mentioned above, the origin of the other hand syndrome is in a corpus callosum injury. This structure is responsible for the union and transmission of information between the two cerebral hemispheres, as well as ensuring that the two work in a coordinated manner.
However, a lot of research suggests that this syndrome cannot only be explained by this type of injury, but is probably also due to some type of cortical damage or frontal lobe injury.
These brain injuries can be due to many incidents, Such as tumor masses, brain aneurysms, traumatic brain injury, or brain surgery such as the aforementioned comisurotomy.
What is the diagnosis?
Because the syndrome of the other hand has exclusively organic causes, its diagnosis is based almost exclusively on development of a clinical history and a comprehensive physical examination.
The tests that the doctor must perform for an effective diagnosis of this disorder include neuroimaging tests, Such as computed tomography (CT) or nuclear magnetic resonance imaging. These techniques make it possible to assess the state of the nervous system and the severity of brain damage.
Is there a treatment?
So far, no effective treatment protocol has been developed for other hand syndrome. When this condition is caused by brain damage associated with tumors or aneurysms, treatment of these should decrease the symptoms of this syndrome.
However, symptomatic treatment can be done for psychological symptoms. In addition, the patient can undergo training through which he can keep the affected limb busy and so on reduce the amount of unwanted movement.