###### Created: 2022-11-30 13:10 ###### Areas & Topics: #medicine #psychiatry ###### Note Type: #permanent ###### Connected to: [[]] - Alien Hand Syndrome (AHS), also known as Dr. Strangelove Syndrome, is a rare disorder which is characterised by a patient's hand acting independently of their own desires. - It has also been reported to not be confined to affect a patient's upper limbs but also their legs, in which it is known as Alien Limb Phenomena. ### Fun Facts - AHS was first reported in 1908 by Kurt Goldstein, describing a woman who lost control of her hand before it began forcibly choking her. - Dr. Strangelove, the main character in Stanley Kubrick’s 1964 film of the same name, had AHS which led to its alternate name. ### Epidemiology - Alien Hand Syndrome appears to mainly affect patients in middle and older age, with some rare cases being seen in children suffering from [[Parry-Romberg Syndrome]] (a severe disorder causing facial atrophy and possible misshaping of the skull). - It has most commonly been seen in patients who have suffered from strokes, Corticobasal Syndrome and Creutzfeldt-Jakob disease, but has been reported in a variety of other cases. ### Aetiology - The main aetiology of AHS stems from disease, trauma or degeneration of the brain and its associated structures. - Affected areas of the brain which seems to play a significant role in AHS include the supplementary motor area, corpus callosum and parietal lobe. - These areas all have key roles in motor planning, inhibition, sensation, and control of contralateral limbs. Therefore, any lesion or dysfunction in any or all of these regions can lead to similar, but different, presentations of AHS. **Theory 1** - The corpus collosum is the white matter commisure which connects the right and left hemispheres of the brain. - It also functions in aiding control of opposite limbs and preventing involuntary movement. - It is hypothesised that when the corpus collosum is damaged, these control mechanisms may become impaired. - This may then lead to patient's having difficulty in controlling their hands simultaneously or stopping involuntary movement in one of their hands which may lead to the movements or feeling of a foreign hand associated with AHS. **Theory 2** - In the brain, the Medial Frontal Lobe contains the Supplementary motor area (SMA). - This area is thought to be involved in the initiation of voluntary movement, as well as the inhibition of unwanted movements. - When damage to this area occurs, it is therefore hypothesised that this may lead to an impaired ability to inhibit unwanted movements in the so called "alien limb". **Theory 3** - The parietal lobe is an important area for processing sensory information. - It is thought that damage in the parietal lobe might result in a deficit of sensory input from the alien limb. - This may contribute to problems coordinating movement in the alien limb and also lead to the patient perceiving the limb as foreign. #### The Three Variants - There is some debate about how many variants of AHS there should be but most of the literature seems to agree on three main variants thus far **Frontal Variant** Cause - It is usually due to a dominant (left) medial frontal lobe lesion (medial prefrontal cortex, supplementary motor area) with or without involvement of the corpus callosum (anterior cingulate gyrus, anterior corpus callosum, or callosal genu) - It is most commonly a result of stroke in the anterior communicating artery territory, which supplies the medial frontal cortex and anterior callosum Features - It most commonly affects the right hand - Characterized by impulsive groping, compulsive manipulation of objects, and difficulty releasing objects when grasped. - Additional features include other frontal lobe signs (leg or arm weakness, non-fluent speech, grasp reflex) - The patient is aware that the arm belongs to them but is unable to voluntarily suppress movements. - They may try and restrain the limb by sitting on it or holding it between their legs **Callosal Variant** Cause - It is mostly caused by isolated corpus callosum injury. - It is most commonly due to surgical resection (callosotomy), callosal hemorrhage or infarct, or callosal demyelination Features - The callosal form exclusively affects the non-dominant (left hand) in right-handed patients - It is characterized by IMC, with minimal limb weakness and absence of frontal features. (Feinberg, Goldberg) - Other clinical features of the callosal disconnection syndrome are present (apraxia, tactile anomia, visual anomia, agraphia, neglect, alexia) **Posterior Variant** Cause - The lesion is typically in the non-dominant (right) parietal lobe (posterior postcentral gyrus, posterior primary sensory cortex, and tertiary somatosensory cortex in the superior parietal lobule) - Uncommonly, the occipital lobe and thalamus are involved - Common etiologies are neurodegeneration of the parieto-occipital cortex (corticobasal syndrome (CBS), Creutzfeldt-Jakob disease (CJD), and stroke in the parietal lobe or posterior cerebral artery territory Features - The posterior variant more commonly affects the non-dominant (left) hand - It is associated with strong feelings of estrangement from the affected limb, less complex motor activity (e.g., limb levitation, ataxia, non-purposeful or non-conflicting movements), and parietal sensory deficits (visual or sensory neglect, body schema dysfunction, hemiasomatognosia, spatial neglect, or astereognosis) ### Signs and Symptoms The main clinical features characteristic of Alien Hand Syndrome are: - Involuntary limb movements (which can be purposeful or non-purposeful) - A sense or delusion of lost ownership or control of the affected limb(s) - Possible accompanying frontal/callosal/posterior signs AHS most commonly affects a patient’s non-dominant hand (typically left). It’s typically unilateral but can be bilateral depending on the aetiology. Additional Features - Patients may be unaware of the movement of their hand, until its movement is pointed out to them or the movement draws the patient's attention to it. - The patient may experience the affected hand acting in a directly opposite way to their unaffected hand, particularly in patients with damage to the corpus callosum. - Patients may express self-criticism, frustration, and annoyance with the limb. - They may hit it, admonish it, or personify it as “mischievous.” - They may not perceive it not as their own, thus truly alien. - Rarely, they may be frightened by it. N.B. It is worth noting that there are a large number of factors that can influence presentation. Some important factors include a patient’s natural hand dominance, past or present neurological lesions, their sites and a patient’s pre-existing illnesses or medical conditions. ### Related Syndromes - Utilisation Behaviour (sometimes known as bilateral AHS)- where a patient is compulsively directed to use an object due to its presence in their environment (e.g. you see a hairbrush on a table and start brushing your hair out of compulsion). - Environmental Dependency Syndrome - where a person is unable to act in a self-directed manner and becomes completely dependant on objects in their environment to guide their behaviour. ### Resources 2 Minute Neuroscience: Alien Hand Syndrome https://www.youtube.com/watch?v=e-NfY_DnWNM&ab_channel=NeuroscientificallyChallenged The Alien Hand Sydrome: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4059570/ Pathophysiology and Treatment of Alien Hand Syndrome: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4261226/ Alien Hand Syndrome: https://link.springer.com/article/10.1007/s11910-016-0676-z The Alien Hand: Cases, Categorizations, and Anatomical Correlates: file:///C:/Users/darcy/Downloads/The%20Alien%20Hand_%20Cases,%20Categorizations,%20and%20Anatomical%20Correlates%20(Behavioral%20and%20Cognitive%20Neuroscience%20Reviews,%20vol.%202,%20issue%204)%20(2003).pdf