How would you feel if one of your hands began to move and perform actions on its own, and you were completely unable to control it?

It would surely be a highly distressing and frustrating experience.

As bizarre as it sounds, this condition, known as alien hand syndrome, is a very real and disabling, albeit rare, complication of certain neurological pathologies.

So, what exactly is this phenomenon and why does it occur?

What is Alien Hand Syndrome?

Alien hand syndrome (AHS) is a rare neurological disorder wherein a person experiences involuntary, purposeful limb movements without having any conscious intention of performing them (Bru et al. 2021; Hassan & Josephs 2016).

Rather than spasms or convulsions, these involuntary movements are purposeful, coordinated and goal-directed actions that appear as if the limb is being controlled by another person (Moawad 2016; Pacella & Moro 2022).

AHS has only been observed to affect one limb at a time, and while it typically affects the hand, there have been cases of similar symptoms occurring in the legs (Anderson & Juber 2022).

Individuals with AHS often feel a loss of ownership and control over their affected limb, with many describing it as having ‘a mind of its own’ (Hassan & Josephs 2016; Panikkath et al. 2014). Some patients even speak about their limb in the third person (Horton 2015).

The condition is sometimes referred to as ‘Dr Strangelove syndrome’, based on the 1964 movie Dr Strangelove, wherein the titular character experiences AHS (Helmstaedter et al. 2021).

What Causes Alien Hand Syndrome?

AHS is associated with damage to parts of the brain caused by:

• Stroke
• Trauma
• Tumours
• Cancer
• Neurodegenerative disease
• Brain aneurysms
• Neurosurgery, particularly corpus callosotomy (split-brain surgery), a procedure sometimes used to treat epilepsy wherein the two brain hemispheres are separated.

(Cronkleton & Morrison 2018)

Although more research is needed in order to fully understand why AHS occurs, MRI scans of those with the condition have provided one possible explanation (Anderson & Juber 2022; Panikkath et al. 2014).

In a typical person, motor activities involve the activation of a vast array of neural networks. However, in those with AHS, only the contralateral primary motor area - which is responsible for initiating motor movements - appears to activate. This excludes the nonprimary motor cortex, which is involved in the planning and selection of movements. Therefore, the spontaneous and unintentional movements caused by AHS may occur because the contralateral primary motor area is being triggered without the activation of intentional planning systems (Panikkath et al. 2014; Guy-Evans & Mcleod 2021).

Types of Alien Hand Syndrome

AHS appears to be associated with injury to one of three specific regions of the brain. These are:

• The frontal lobe (particularly the supplementary motor area and anterior cingulate cortex)
• The corpus callosum
• The parietal lobe.

(Anderson & Juber 2022; Panikkath et al. 2014)

Depending on the location of the injury, AHS can be categorised as either anterior (frontal or callosal injury) or posterior (parietal injury) in nature (Hassan & Josephs 2016).

Symptoms of Alien Hand Syndrome

People with AHS may experience a variety of involuntary movements from the affected limb, such as:

• Self-groping (e.g. touching the face)
• Goal-directed tasks (e.g. buttoning up a shirt)
• Grasping objects
• Refusal to release held objects
• Levitating (rising into the air)
• Oppositional actions (e.g. closing a drawer that the unaffected hand has just opened)
• Self-suffocation
• Less purposeful movements like waving around.

(Cronkleton & Morrison 2018; Panikkath et al. 2014; Anderson & Juber 2022)

The patient might display autocriticism in response to these involuntary movements, for example, slapping the ‘alien’ hand with their unaffected hand (Panikkath et al. 2014).

AHS seems to present differently depending on the area of the brain that has been injured. For example, damage to one side of the frontal lobe often causes the hand on the opposite side of the body to perform purposeful movements such as reaching and grasping, and the person might have difficulty releasing an object being held. Posterior injury seems to cause the affected limb to withdraw rather than reach, and it may ‘levitate’ upward and away from surfaces. Corpus callosum injury appears to affect the person’s non-dominant hand and causes intermanual conflict (where the hands perform opposing actions) (Bionity n.d.).

Diagnosis of Alien Hand Syndrome

AHS is difficult to diagnose for several reasons:

• It’s a neurological condition without a psychiatric component
• It may be misdiagnosed as a psychiatric disorder or behavioural issue due to the rarity of AHS
• There are very few reported cases of AHS in literature, and therefore, healthcare practitioners may be unfamiliar with the condition.

(Anderson & Juber 2022; Moawad 2016)

Consequently, diagnosis requires thorough observation and evaluation of symptoms, as well as patient history, clinical examination and an MRI scan to look for lesions in the brain (Moawad 2016; Fitzgerald 2021).

Treatment for Alien Hand Syndrome

There is no specific cure for AHS, but symptoms may resolve on their own. This has been found to take anywhere between 30 minutes to several years (Panikkath et al. 2014).

There are a variety of treatments that have been attempted with varying degrees of success, but many of these are based on anecdotal evidence only. They include:

• Muscle control therapies
• Neuromuscular blocking agents
• Benzodiazepines
• Mirror box therapy
• Cognitive therapies
• Learning task behavioural therapies
• Visuospatial coaching
• Physical and occupational therapies
• Distracting the affected limb by having it hold something
• Patient-initiated restriction of the affected limb (e.g. sitting on it, wearing an oven mitt)
• Giving verbal commands to the affected limb.

(Cronkleton & Morrison 2018; Anderson & Juber 2022)

Caring for Patients With Alien Hand Syndrome

When caring for a patient who is experiencing AHS, you may wish to consider the following strategies:

• Keeping the patient’s affected hand occupied (e.g. with a stress or tennis ball) when working in close proximity to them
• Ensuring the environment is clutter-free, and that objects are not in reach of the affected hand (this reduces the risk of accidents)
• Creating a calm and stress-free environment (e.g. accommodating the patient in a single room, which also promotes sleep hygiene)
• Using visualisation tactics such as positioning the affected hand within the patient's visual field and encouraging the patient to mentally practise functional tasks using both limbs
• Minimising distractions for the patient when providing care or therapy
• Managing fatigue by scheduling therapy and care throughout the day, depending on the patient’s fatigue levels.

(Horton 2015)

In the event of a situation wherein a patient grips or gropes a staff member, patience is required in managing the incident. If required, release the patient's grip gently by prising off the little and ring fingers followed by the remaining fingers. Pulling away or forcing the release will in many instances only increase the force of the grip. Panic will increase anxiety for both the staff member and the patient, which could exacerbate the situation further (Horton 2015).

Conclusion

Remember that AHS is an often frustrating and disabling condition that can be highly distressing for patients. It’s therefore essential to provide empathetic and patient care to these individuals.