Alien hand syndrome is a violation of the ability to perform controlled actions in combination with uncontrolled movements of the upper limb. It is accompanied by uncontrolled, often purposeful motor activity of the hand, its forced position, sensitivity disorders. Diagnosis is based on the patient’s complaints, anamnestic data and the results of a physical examination. Laboratory and instrumental methods of examination are used to identify the root cause. The treatment is symptomatic, based on the control of movements with the help of household items or special orthopedic bandages.
General information
Alien hand syndrome is a relatively rare clinical phenomenon. According to various sources, the prevalence rate for HR is 0.5-1 case per 100 thousand population. The disorder was first described in 1907. In 1908, German neurologist Kurt Goldstein prepared a full-fledged clinical description of a patient suffering from this disease. At certain intervals, the pathology was called “the hand of a foreigner”, “diagnostic apraxia“. The term used today was proposed by the American neurophysiologist Joseph Bogen. The name based on the name of the hero of the popular feature film “Dr. Strangelove’s disease” is also widely used.
Causes
Alien hand syndrome is not an independent disease – it plays the role of one of the clinical manifestations of other diseases. Most of them are associated with degenerative-dystrophic changes in various structures of the central nervous system, mainly the cerebral cortex. Most often , AHS accompanies the following diseases and disorders:
- Neurodystrophic pathologies. The formation of diagnostic apraxia may be due to corticobasal degeneration (the most common cause), Alzheimer’s and Creutzfeldt-Jakob disease, multiple sclerosis, leukodystrophy and agenesis of the corpus callosum.
- Traumatic injuries. They include open craniocerebral injuries, severe concussions of the brain, epidural hematomas and the consequences of neurosurgical interventions. This can also include compression of CNS tissues in massive benign or malignant neoplasms.
- Cerebrovascular disorders. AHS is observed with large cerebral artery aneurysms, transient ischemic attacks, in the acute period of ischemic stroke, less often – with its hemorrhagic variant.
Pathogenesis
The exact mechanism of the syndrome is unknown. In modern neurology, it is believed that this disorder is caused by a violation of friendly control (disconnection) between the anterior and posterior parts of the brain of the dominant hemisphere. Because of this, it becomes impossible to self-correct the movements of the upper limb, carried out with the help of visual and proprioceptive feedback signals. This data indirectly confirms improvements in hand control while maintaining eye contact.
Clinical manifestations of the condition decrease with the stimulation of tactile and deep types of sensitivity – pressing the limb to the body or resting on any surface. The role of cortical irritation in the genesis of AHS is also indicated by accompanying paresthesia and experimental modeling with simultaneous irritation of the visual, tactile and articular-muscular zones of the brain. This hypothesis is confirmed by the involvement of the parietal cortex and ischemia of the basal ganglia according to the results of neuroimaging methods.
Symptoms
It is customary to distinguish three variants of the clinical picture of alien hand syndrome, which depend on the localization of the pathological focus in the central nervous system. The callosal variant of AHS occurs when the corpus callosum is affected, regardless of the preservation of the frontal lobe. A specific clinical manifestation of this form is the provocation of violent movements of a “foreign” hand by the activity of a controlled limb. The affected limb in most cases performs the opposite action, as if entering into a confrontation with a healthy one. The phenomenon is called “intermanual conflict”. Reflexes of oral automatism are not observed.
The frontal or frontal form develops when the frontal lobe of the dominant hemisphere is affected in the area of the anterior cingulate gyrus or the perforant cortex adjacent to the corpus callosum. It is clinically manifested by the appearance of involuntary movements in the contralateral hand aimed at interacting with objects, such as swiping, groping or grasping. There is a provocation of symptoms by eye contact or mechanical action. Less often, paresthesia occurs by the type of tingling sensation, cold or numbness. In difficult cases, the actions of an uncontrolled limb are threatening in nature – the hand can strangle, strike the patient. The examination reveals pathological subcortical reflexes – grasping and Marinesko-Radovichi.
The posterior or sensory form of the syndrome is caused by the involvement of the parietal and occipital lobes of the non-dominant hemisphere or thalamus in the pathological process. It differs in less coordinated movements than in other variants. The “alien” limb often “levitates” or occupies a typical “parietal arm” pose. Without visual control, the patient cannot determine the belonging of the limb and complains about the feeling of its “alienness”. This variant of AHS is characterized by a syndrome of ignoring or neglect, in which spatio-visual disturbances occur in the form of a lack of perception of stimuli from the half of the body innervated by the affected area.
Diagnostics
The diagnosis of alien hand syndrome is based on the complaints of the patient himself and physical examination. General clinical laboratory and hardware diagnostic methods are prescribed to identify the underlying pathology. Differentiation with the syndromes of hemiataxy, hemiballism, athetosis and pseudoatatosis is important. The diagnostic program for AHS usually includes the following items:
- Collecting anamnesis. During the patient’s interview, a neurologist finds out the circumstances that preceded the appearance of the disorder, the dynamics of its development, previously transferred or currently existing diseases of the central nervous system, the treatment carried out on this occasion and its results.
- External inspection. During the initial visual examination, attention is focused on the nature of involuntary movements in the “alien” hand, the ability to perform controlled actions, interaction with surrounding objects, the presence of trigger factors and reactions when exposed to them.
- Determination of somatic and neurological status. During the physical examination, a diagnostic search is carried out for symptoms and syndromes of the underlying disease or a pathological condition that can provoke AHS. Close attention is paid to tone, reflex activity, muscle strength, the presence of anisoreflexia and pathological reflexes, including reflexes of oral automatism, changes in surface and deep sensitivity.
- Neuroimaging. Cerebral MRI is aimed at finding an organic substrate underlying diagnostic apraxia. The results of the study are the basis for establishing a definitive diagnosis.
Treatment
There is no full-fledged treatment of alien hand syndrome. The therapy carried out is aimed at eliminating the underlying disease that caused AHS, and relieving individual symptoms. In some cases, for example, with ischemic stroke, treatment is not required, since the syndrome gradually regresses independently along with the restoration of cerebral circulation. In situations where the elimination of primary pathology does not lead to the relief of diagnostic apraxia, the following therapeutic approaches can be used:
Tactile stimulation. In some patients, it is possible to partially or completely eliminate spontaneous movements in the hand with the help of constantly held objects, for example, a cane or an expander. Warm water and restraining the “alien” hand with a healthy limb can be effective.
Orthopedic bandages. This option is based on the use of special pads or bandages that limit the amount of movement in the limb. The method is not used in patients with positive dynamics, because it can slow down the process of restoring voluntary movements.
Prognosis and prevention
The possibility of complete relief of the syndrome directly depends on the pathology that provoked it. In acute conditions (stroke, traumatic brain injury) and good neuroplasticity, the disorder regresses without a trace on its own. In neurodystrophic lesions, the AHS is aggravated along with the experience of the disease, which is associated with muscle hypotension. Specific prevention of diagnostic apraxia has not been developed. Non-specific preventive measures are based on the prevention of common causes of this syndrome.