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What is alien hand syndrome
Alien hand syndrome or Dr. Strangelove syndrome, is a disorder of involuntary, yet purposeful, hand movements in which a person loses control of his or her hand, which starts to act independently, that may be accompanied by agnosia, aphasia, weakness, or sensory loss 1). Alien hand syndrome is described as involuntary complex goal-directed activity of one limb 2). Recent usage of the term “alien hand” is more liberal and requires having observable involuntary motor activity along with the feeling that the limb is foreign or that it has a will of its own 3). Alien hand syndrome has been reported after surgery on the corpus callosum and with brain tumors, aneurysms, degenerative diseases of the brain, and uncommonly stroke 4). Alien hand as a manifestation of cardioembolic stroke is extremely rare, with only a few cases reported in the literature 5).
Alien hand syndrome is a higher-order, motor control disorder featuring involuntary, yet purposeful, movements 6). The affected limb is typically the hand, although leg (alien limb phenomena) involvement has been reported 7). In alien hand syndrome there is a complex sense of limb foreignness 8), including misidentifying the limb as the examiner’s. Sometimes the limb is personified 9): patients have named their alien hands.
By definition, the limb movements are not the result of movement disorders. Alien hand syndrome may be associated with other neurological deficits, including decreased motor spontaneity, speech hesitation, apraxia, tactile dysnomia, and behaviors associated with frontal lobe dysfunction 10). The movements are sometimes so bizarre that they may be misinterpreted as functional 11).
Alien hand syndrome has been reported to be associated with several abnormal involuntary movements when different regions of the brain, like the corpus callosum, parietal region, or frontal region, are involved. It can be classified into at least four categories: 1) diagnostic dyspraxia/intermanual conflict (when one hand performs actions contrary to the other hand); 2) alien hand sign (a subjective feeling that the hand is not one’s own); 3) syndrome of anarchic hand (when the affected hand performs goal-directed activity not under the will of the person); and 4) supernumerary hand (a feeling of having an extra limb) 12). Another type of alien hand is the levitating hand, where the affected limb tends to levitate without volitional action 13).
Alien hand syndrome might manifest as a self-groping behavior and self-oppositional behavior 14). Autocriticism has also been reported, with the person slapping the alien hand with the normal hand. The person loses control of the affected hand as if it is being controlled by an external force. The alien hand might grab onto things and the person might have to use the other limb to release the objects from it. At extremes, the alien hand has been reported to even suffocate the patient.
Alien hand syndrome has been reported to last for several days to several years. Alien hand syndrome tends to be transient in patients with partial loss of the corpus callosum genu and splenium; in addition, patients with unilateral callosal lesions may regain connectivity between the two hemispheres if the remaining corpus callosum is functional 15). Alien hand as a manifestation of cardioembolic transient ischemic attack has been reported only once based in a review 16). The extremely short duration of alien hand in this case report (30 minutes) is the shortest reported duration of this phenomenon recorded 17). Permanent alien hand syndrome may develop when the infarction involves two thirds of the anterior corpus callosum 18). Quick recovery was noticed following antiplatelet therapy in the present case, suggesting that the remaining corpus callosum may have compensated for the lesioned site, and that connectivity between the bilateral cerebral hemispheres was re-established.
There is no established treatment for alien hand syndrome.
Alien hand syndrome causes
Although there are methodological differences between the different papers cited, the evidence seems to suggest that most cases of alien hand syndrome arise from the disruption of interhemispheric connections, and/or of the connections between the frontal areas and the parietal lobes 19). Common causes of alien hand syndrome include anterior cerebral artery strokes 20), midline tumors, and neurodegenerative illnesses. Rarer causes include spontaneous pneumocephalus 21), migraine aura 22), seizure 23) and Parry–Romberg Syndrome, a presumed autoimmune disorder with progressive facial hemiatrophy 24).
Lesions implicated in causing alien hand syndrome include those in the corpus callosum and/or posterior parietal cortex, supplementary motor area, and the anterior cingulate cortex 25). Functional MRI has been used to study brain activity in patients with alien hand syndrome 26). In normal individuals, initiation of motor activity shows activation of multiple extensive neural networks. However, in patients with alien hand syndrome, only isolated activation of the contralateral primary motor cortex is observed 27). It has been proposed that lesions in the parietal cortex result in isolated activation of the contralateral primary motor area due to its release from the intentional planning systems. Damage to the parietal cortex can also cause lack of awareness of movements due to loss of proprioceptive feedback or left hemineglect 28). The combination of these factors results in initiation of spontaneous movements without the patient’s knowledge or will.
Alien hand syndrome symptoms
Alien hand syndrome is a disorder of involuntary, yet purposeful, hand movements in which a person loses control of his or her hand, which starts to act independently, that may be accompanied by agnosia, aphasia, weakness, or sensory loss 29). Alien hand syndrome is described as involuntary complex goal-directed activity of one limb 30). Recent usage of the term “alien hand” is more liberal and requires having observable involuntary motor activity along with the feeling that the limb is foreign or that it has a will of its own 31).
Major alien hand syndrome symptoms include 32):
- intermanual conflict (61.3%),
- grasp reflect (61.3%) and
- alien hand signs (12.5%).
Among the 7 patients with simple corpus callosum infarction, intermanual conflict occurred in 6 cases (85.7%), while grasp reflex was seen in 2 cases (28.5%) 33). Among the 24 patients with complex corpus callosum infarction, intermanual conflict was reported in 13/24 (54.2%) patients, while grasp reflex was observed in 17 cases (70.8%) 34). Within the 17 grasp reflex patients, 14 (82.3%) had infarction at the medial frontal cortex, cingulate gyrus or supplementary motor cortex. In addition, 2/24 (8.3%) complex corpus callosum infarction cases were reported to experience involuntary masturbation 35).
Alien hand syndrome might manifest as a self-groping behavior and self-oppositional behavior 36). Autocriticism has also been reported, with the person slapping the alien hand with the normal hand. The person loses control of the affected hand as if it is being controlled by an external force. The alien hand might grab onto things and the person might have to use the other limb to release the objects from it. At extremes, the alien hand has been reported to even suffocate the patient.
Alien hand syndrome treatment
There are no approved or recommended therapies for alien hand syndrome, and alien hand syndrome management is based on anecdotal reports of both pharmacologic and behavioral interventions (Table 1). A notable report is that of a 13-year-old female with right-arm levitation, after a left anterior thalamic infarction, who responded to clonazepam and botulinum toxin. Two days after starting 1 mg of clonazepam daily, she had a 70% reduction in the number of levitations per minute (LE/min) and spontaneous grasps per minute (SG/min). Unfortunately, poor tolerance prompted discontinuation. She subsequently received 600 units of botulinum toxin type A into the deltoid, triceps, biceps, flexor carpi ulnaris, and finger extensors of the right arm, which caused an 80% improvement in the LE/min and SG/min. Clonazepam possibly potentiated her thalamic GABAergic circuitry, which likely resulted in either reducing the arm’s oversensitivity to external stimuli or dampened the internal stimulus driving the alien hand syndrome. In contrast, botulinum toxin possibly helped either by weakening the arm or by altering sensory feedback 37).
Table 1. Treatment Modalities Described in Different Alien Hand Syndrome Variants
| Variant | Therapeutic Modality |
|---|---|
| Anterior | Sensory tricks |
| Distracting tasks | |
| Cognitive behavioral therapy (CBT) for anxiety control | |
| Verbal cues | |
| Posterior | Botulinum toxin A |
| Clonazepam | |
| Visualization strategies | |
| Spatial recognition tasks |
In terms of rehabilitation strategies, treatments focusing on the patient’s needs are most beneficial. In one report of a man with a left superior frontal stroke and right alien hand syndrome, educating the patient and caregiver about his condition, providing coping strategies (such as distracting the affected hand with an object), and using visualization tactics allowed him to regain his functional independence. These tactics focused on planning, visualizing every movement of both hands during the task, and organizing the sequences of the task. In addition, he was instructed to perform tasks that would trigger unwanted actions by the affected hand and subsequently cued to perform coping strategies, such as placing the hand in his pocket or distracting it with a ball. The outcomes from these interventions were measured with the functional index measure, which improved from 83 out of 126 to 119 out of 126 39). Similar success from avoidance coping mechanisms was reported in a patient with alien hand syndrome following resection of a frontal tumor. In this report 40), the patient was prompted to hold on to large stationary objects to occupy the alien hand while his normal hand performed daily tasks.
In two patients with vascular lesions, behavioral modifications improved quality of life. In a patient with a right hemispheric stroke, placing the left hand in the right hemispace or restraining it while performing tasks was beneficial. Meanwhile, a patient with a left frontal lesion was able to control her anger and frustration about the involuntary movements with cognitive behavioral therapy. This allowed her to better utilize the affected hand 41).
Another patient with posterior alien hand syndrome improved with spatial recognition exercises; the patient was trained first to recognize different shapes and spatial arrangements and later to transfer the acquired skills to his daily tasks, thus potentially improving his bimanual coordination 42).
Anecdotally, verbal cues ameliorated symptoms of alien hand syndrome 43). In this report 44), a patient was asked to accurately and quickly perform both exogen ous (in response to a stimuli) and endogenous (internally predetermined, sequential responses) tasks. The patient performed poorly in endogenous tasks with the affected hand. The errors only increased with the number of distractions. However, when verbal cues were added to the endogenous tasks, the patient performed better 45).
Visual reinforcement may aid in controlling abnormal movements. In a patient with right alien hand syndrome, placing the affected hand in a mirror box so that it may not only “see” the normal hand but also be confined in space allowed better control of both gross and fine movements, such as finger tapping. However, long-term benefits of this therapy are not known and it is possible that only posterior alien hand syndrome may benefit due to reliance on sensorimotor integration 46).
A sensory trick may also alleviate symptoms. A 67-year-old male with alien hand syndrome following a stroke developed groping and grasping movements of his left hand that disrupted his sleep. To alleviate his distress, a simple oven mitt was placed over the hand, and his movements significantly improved, allowing him to sleep comfortably. The oven mitt likely provided enough stimulation for the sensory spinal grasp reflex to achieve accommodation, thus inhibiting the movements 47).
Despite all of these anecdotal reports, long-term data on rehabilitation are scarce. In two patients with frontal alien hand syndrome, gradual improvement of grasping and groping at 6 months was reported. Unfortunately, the strategies used in therapy, including using both hands for tasks and suppressing involuntary movements, were not retained by the patients long-term. Despite that, the caregivers did report gradual improvement in alien hand syndrome symptoms at their follow-up visits 48).
Similarly, our limited understanding of the pathophysiology of alien hand syndrome makes it difficult to accurately predict its natural history. Data from mixed variants suggest that callosal forms likely resolve faster than frontal variants 49). Another case suggested good prognosis in those with posterior alien hand syndrome from strokes without significant intervention 50).
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