Foreign hand syndrome: symptoms, causes and treatment
Our brain is made up of two hemispheres united by a bundle of nerve fibers that make up the corpus callosum. Thanks to this structure, both hemispheres can exchange information and, together with the action of other brain areas, we can be aware of our own body.
However, when this structure fails or is injured may appear a strange disorder known as foreign hand syndrome by which the person is unable to control the movements of his own arm and hand that can be experienced as alien or, even, as possessed.
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What is the syndrome of the hand of others?
Also known as "strange hand syndrome", "alien hand syndrome" or "dr. Strangelove ", this strange disorder of neurological origin is distinguished by causing in the person who suffers it all kinds of involuntary and uncontrolled movements in one of the upper extremities .
In addition, another of the peculiarities of the syndrome of the hand of others is the sensation of strangeness that the person feels with respect to said extremity. That is, the patient experiences a personification of the arm and hand, which seems to have a life of its own .
The first time this syndrome was described was in the year 1908. The famous German doctor Kurt Goldstein discovered these strange symptoms in patients who had undergone a commissurotomy. This intervention consists of making a cut in the corpus callosum and was typical of the treatments for very serious epilepsies, with the aim of preventing such attacks from spreading from one cerebral hemisphere to another.
Clinical classification
There are two different types of hand syndrome, which differ in relation to the causes and anatomical correlates of this syndrome.
1. Acute variant of the syndrome
One of the ways in which the syndrome manifests is the acute variant, which is due to damage to the corpus callosum. cause temporary changes in the supplementary motor area . It is hypothesized that these damages are due to a hemispheric retraction during the commissurotomy.
This acute variant is characterized by more intense and exaggerated movements, but of short duration.
2. Chronic variant
The second form that adopts the syndrome of the hand of others is the chronic variant. The cause of this is due to a lesion in the corpus callosum, as well as injuries in the supplementary motor area, which is located in the medial frontal lobe.
What symptoms appear?
The clinical picture of the syndrome of the hand of others has two fundamental symptoms. These symptoms are:
Dissociation
Sensation of dissociation of the affected limb. The person firmly believes that said arm is not part of his body and that, therefore, it can not exercise any control over its movements. However, tactile sensibility is preserved, so even though the person can not control it, they can feel everything that happens to the limb.
Absence of control of movements
The patient is not aware of the actions performed by the affected arm and hand . That is, the person does not realize when the limb is making any kind of movement, regardless of how complicated or exaggerated it may be.
In many cases, movements performed by the extremity considered to be external cause interferences with the movements or actions carried out by the healthy limb. In addition, this neurological alteration dissociates the intention of the action so that the impulses of the other hand are totally opposed to those of the healthy hand.
Context influences
After the observation of cases, it has been detected that these "foreign extremities" they tend to react in response to nearby stimuli like eye-catching objects that are within your reach. Hence, it is hypothesized that the behavior of these extremities is guided by contextual stimuli.
The intensity of the symptoms may vary in a fluctuating manner. In highly stressful or anxious situations , the clinical picture of the syndrome of the hand of others tends to increase both in quantity and intensity.
Finally, these symptoms can lead to a large number of psychological and emotional side effects. This associated symptomatology can range from feelings of confusion and anxiety, to Experimentation of fear and crisis of fear or panic . However, the psychological consequences can vary a lot between patients since many of them learn to live with this type of disorder.
What causes does it have?
As mentioned above, the origin of the syndrome of the hand of others is found in a lesion of the corpus callosum . This structure is responsible for uniting and transmitting information between both cerebral hemispheres, as well as ensuring that both work in a coordinated manner.
However, there are numerous investigations that point to the idea that this syndrome can not be explained only by this type of injury, but probably also due to some type of cortical damage or injury in the frontal lobe.
These brain damage may be due to numerous incidents , such as tumor masses, cerebral aneurysms, traumatic brain injuries or cerebral surgeries such as the aforementioned comisurotomy.
Which is the diagnosis?
Because the syndrome of the hand of others has exclusively organic causes, its diagnosis is based almost exclusively on the preparation of a medical history and a thorough physical examination .
The tests that the doctor must carry out for an effective diagnosis of this disorder they include neuroimaging tests , such as computerized axial tomography (CT) or nuclear magnetic resonance. These techniques allow to assess the state of the nervous system and the severity of brain injuries.
Is there a treatment?
At the moment, no effective treatment protocol has been developed for the hand syndrome of others. When this condition is caused by brain lesions associated with tumors or aneurysms, the treatment of these should diminish the symptomatology of this syndrome .
However, symptomatic treatment can be performed for psychological symptoms. In addition, the patient can undergo a training by which he can keep the affected limb occupied and thus reduce the amount of unwanted movements .
