What is the Difference Between Akinetic Mutism and Locked-In Syndrome

Both akinetic mutism and locked-in syndrome are categorized as rare conditions related to the brain. Akinetic mutism is often misdiagnosed as delirium, depression, or locked-in syndrome, as these conditions show some overlapping symptoms. However, each of these conditions has specific symptoms which can confirm their correct diagnosis.

The key difference between akinetic mutism and locked-in syndrome is their symptoms. Akinetic mutism is a condition where people are conscious but may have extreme difficulties moving and speaking, while locked-in syndrome is a condition where people are conscious but are physically paralyzed.

CONTENTS

1. Overview and Key Difference
2. What is Akinetic Mutism 
3. What is Locked-In Syndrome
4. Similarities – Akinetic Mutism and Locked-In Syndrome
5. Akinetic Mutism vs Locked-In Syndrome in Tabular Form
6. Summary – Akinetic Mutism vs Locked-In Syndrome
7. FAQ – Akinetic Mutism and Locked-In Syndrome

What is Akinetic Mutism?

Akinetic mutism is a condition where a person does not move (akinesia) or speak (mutism). It was first described in 1941 as a mental state. The symptoms of this condition may include lack of motor function (but not paralysis), lack of speech, apathy, slowness, and disinhibition. Akinetic mutism often occurs after brain injury or as a symptom of other diseases.

Akinetic mutism can be diagnosed through physical examination, neurological examination, and brain scans such as PET scan, CT scan, and MRI. Furthermore, treatment options for akinetic mutism include using intravenous magnesium sulfate, which relieves symptoms, removal of cysts causing akinetic mutism, and dopamine agonist therapy.

What is Locked-In Syndrome?

Locked-in syndrome (LiS) is a neurological disorder that occurs when a part of the brainstem is damaged, normally from a stroke. It is characterized by paralysis of voluntary muscles except for those that control vertical eye movements. People with this condition cannot chew, swallow, speak, make facial expressions, or produce any body movements below their eyes.  But they can move their eyes vertically, blink, hear, and comprehend people talking and reading to them, think and reason before getting this disease, and have a sleep-wake cycle. Moreover, locked-in syndrome is caused by damage to the pons in your brainstem.

Figure 01: Locked-In Syndrome

Locked-in syndrome can be diagnosed through physical examination, MRI scan, cerebral angiography, electroencephalogram (EEG), evoked potentials, electromyography, blood tests, and cerebrospinal fluid (CSF) examination. There is no treatment for locked-in syndrome. However, supportive therapy and communication training can help to manage it.

Similarities between Akinetic Mutism and Locked-In Syndrome

1. Both akinetic mutism and locked-in syndrome are caused by brain damage.
2. These conditions may share some overlapping symptoms.
3. Both these conditions can be diagnosed through physical examination and imaging testing.
4. They are normally treated through specific therapies.

Difference Between Akinetic Mutism and Locked-In Syndrome

Definition

1. Akinetic mutism is a condition where people are conscious but may have extreme difficulties in moving and speaking.
2. Locked-in syndrome is a condition where people are conscious but are having paralysis of voluntary muscles except for muscles that control the vertical eye movements.

Causes

1. Akinetic mutism can be caused by a variety of things, such as frontal lobe damage, thalamic stroke, ablation of the cingulate gyrus, and Creutzfeldt–Jakob disease.
2. Locked-in syndrome can be caused by ischemic stroke, infection in certain parts of the brain, tumors, demyelination, amyotrophic lateral sclerosis (ALS), Guillain Barre syndrome, trauma, and substance misuse.

Symptoms

1. The typical symptoms of akinetic mutism are lack of motor function, lack of speech, apathy, slowness, and disinhibition (behavioral disinhibition).
2. The typical symptoms of locked-in syndrome are total paralysis, preserved consciousness, and the ability to communicate only through eye movements or blinking.

Diagnosis

1. Akinetic mutism can be diagnosed through physical examination, neurological examination, and brain scans such as PET scan, CT scan, and MRI.
2. Locked-in syndrome can be diagnosed through physical examination, cerebrospinal fluid examination, electroencephalogram (EEG), cerebral angiography, magnetic resonance imaging (MRI), or computed tomography (CT) scans and electromyography.

Treatment

1. The treatment options for akinetic mutism are providing intravenous magnesium sulfate, removal of cysts that cause akinetic mutism, and dopamine agonist therapy.
2. There is no treatment for locked-in syndrome. Supportive therapy, communication training, physiotherapy, breathing exercises, and regularly changing the individual’s position to enable proper cardiovascular and respiratory function can help to manage the condition.

This summarizes the difference between akinetic mutism and locked-in syndrome.

Summary – Akinetic Mutism vs Locked-In Syndrome

Akinetic mutism and locked-in syndrome are two rare conditions related to the brain. Akinetic mutism is characterized by extremely slow or no bodily movement alongside severely slowed or absent speech, while locked-in syndrome is characterized by no ability to move except with the eyes and no ability to speak. This is the summary of the difference between akinetic mutism and locked-in syndrome

FAQ: Akinetic Mutism and Locked-In Syndrome

1. What is the most common cause of akinetic mutism?

• Akinetic mutism can be caused by various factors such as frontal lobe damage, thalamic stroke, ablation of cingulate gyrus, Creutzfeldt–Jakob disease, respiratory arrest, acute cases of encephalitis lethargica, meningitis, hydrocephalus, trauma, tumors, aneurysms, olfactory groove meningioma, cyst in third ventricle, toxical lesions and infections of central nervous system, and delayed post-hypoxic leukoencephalopathy (DPHL).

2. What is the treatment for akinetic mutism?

• The treatment options for akinetic mutism include providing intravenous magnesium sulfate, which relieves the symptoms, removal of cysts through surgery causing akinetic mutism, and dopamine agonist therapy.

3. What is the main cause of locked-in syndrome?

• Locked-in syndrome is a rare and serious neurological disorder that happens when the brainstem is damaged, usually from a stroke. People with locked-in syndrome have total paralysis but still have consciousness and normal cognitive abilities.

4. How does one know if someone has locked-in syndrome?

• People with locked-in syndrome are paralyzed except for the muscles that control eye movement (vertical eye movements). They are conscious and can think and reason but cannot move or speak. They also may be able to communicate with blinking eye movements.

5. Is there a treatment for locked-in syndrome?

• There is no specific treatment for locked-in syndrome. Because cognitive function is intact and communication is possible, the symptoms of the patients can be managed by supportive therapy, communication training, physiotherapy, breathing exercises, and regularly changing the individual’s position to enable proper cardiovascular and respiratory function.

 Reference:

1.  “Akinetic Mutism Disease.” Malacards – Research Articles, Drugs, Genes, Clinical Trials.
2.  “What Is Locked-in Syndrome?” WebMD.

Image Courtesy:

1. “Brisa Alfaro, 32 year old Pons Stroke and Locked In Syndrome Survivor” By Brisa Alfaro – Own work (CC BY-SA 4.0) via Commons Wikimedia

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