Alien Hand Syndrome: Symptoms, Causes, and Treatment

Our brain is made up of two hemispheres joined 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 a strange disorder known as alien hand syndrome may appear 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 alien hand syndrome?

Also known as “alien hand syndrome”, “alien hand syndrome” or “dr. Strangelove”, this strange disorder of neurological origin is distinguished by causing in the person who suffers from 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 alien hand 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 the hand, which seems to him to have a life of their own.

The first time this syndrome was described was in 1908. The famous German-born physician Kurt Goldstein discovered these strange symptoms in patients who had undergone a commissurotomy. This intervention consists of making a cut in the hard body and it was characteristic of the treatments for very serious epilepsies, with the aim of preventing said attacks from spreading from one cerebral hemisphere to another.

clinical classification

There are two different types of alien hand syndrome, which differ in relation to the causes and anatomical correlates of this syndrome.

1. Acute variant of the syndrome

One of the forms in which the syndrome manifests itself is the acute variant, which is due to damage to the corpus callosum that cause temporary changes in the supplementary motor area. It is hypothesized that these damages are due to hemispheric retraction during commissurotomy.

This acute variant is characterized by more intense and exaggerated movements, but of short duration.

2. chronic variant

The second form that the alien hand syndrome takes is the chronic variant. The cause of this is due to a lesion in the corpus callosum, as well as lesions in the supplementary motor area, which is located in the frontal lobe middle.

What symptoms appear?

The clinical picture of the alien hand syndrome 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 their body and that, therefore, cannot exercise any control over its movements. However, tactile sensitivity is preserved so, although the person cannot control it, they can feel everything that happens to the limb.

Lack of control of movements

The patient is unaware of the actions being performed by the affected arm and hand. That is, the person does not realize when the extremity is performing any type of movement, regardless of how complicated or exaggerated it is.

In many cases, the movements carried out by the extremity considered foreign cause interference with the movements or actions carried out by the healthy extremity. In addition, this neurological alteration dissociates intention from action so the impulses of the alien hand are totally opposite to those of the healthy hand.

The context influences

After observing cases, it has been detected that these "alien extremities" tend to react in response to nearby stimuli such as striking objects that are within your reach. Hence, it is hypothesized that the behavior of these limbs is guided by contextual stimuli.

The intensity of the symptoms can vary fluctuatingly. In highly stressful or high-anxiety situations, the clinical picture of the alien hand syndrome 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 a feeling of confusion and anxiety, to experimentation of fear and attacks of fear or panic. However, the psychological consequences can vary greatly between patients since many of them learn to live with this type of disorder.

What causes does it have?

As previously mentioned, the origin of the alien hand syndrome is found in a lesion of the corpus callosum. This structure is in charge of uniting and transmitting information between both cerebral hemispheres, as well as making sure that both work in a coordinated manner.

However, there are numerous investigations that point to the idea that this syndrome cannot be explained solely caused by this type of lesion, but also probably due to some type of cortical damage or lesion in the lobe frontal.

These brain damages can be due to numerous incidents, such as tumor masses, brain aneurysms, head injuries or brain surgeries such as the aforementioned commissurotomy.

Which is the diagnosis?

Because the alien hand syndrome has exclusively organic causes, its diagnosis is based almost exclusively on taking a medical history and a thorough physical examination.

The tests that the doctor must carry out for an effective diagnosis of this disorder include neuroimaging tests, such as computerized axial tomography (CT) or nuclear magnetic resonance. These techniques make it possible to assess the state of the nervous system and the severity of brain lesions.

Is there a treatment?

At the moment, no type of effective treatment protocol for alien hand syndrome has been developed. When this condition is caused by brain lesions associated with tumors or aneurysms, treatment of these should reduce the symptoms of this syndrome.

However, symptomatic treatment can be performed for psychological symptoms. In addition, the patient can undergo training through which he can keep the affected limb occupied and thus reduce the amount of unwanted movement.