Difference Between Akinetic Mutism and Locked-In Syndrome

Introduction

Akinetic mutism and locked-in syndrome are both classed as rare conditions relations to the brain. Akinetic mutism is a rare condition where there is extremely slow or no bodily movement present, this is often alongside severely slowed or absent speech. Locked-in syndrome is characterized as a neurological disorder, presenting with no ability to move except with the eyes and no ability to speak. These conditions often are mistaken for another, but each has specific symptoms which confirm the correct diagnosis.

Definition 

Akinetic mutism involves the severe slowing and absence of body movement and speech patterns. It is a rare condition that has been reported in patients (often children) suffering brain tumours, central nervous system infections (both bacterial or viral infections), a condition where there is accumulation of fluid in the brain termed hydrocephalus, and on the rare occasion as a post-operative complication. Akinetic mutism results in a severely reduced mental function but a present wakefulness and preserved self-awareness. The long-term prognosis for this condition is currently unknown.

Locked-in syndrome is a rare neurological condition where there is a total state of paralysis in all of the voluntary muscle groups in the body, except for those controlling eye movement. Complete communication is usually possible and done through eye movements and blinking. This syndrome is caused by damage to an area of the brain called the pons. This area is part of the brainstem, and it is responsible for relaying formation to parts of the brain via nerve fibres. Locked-in syndrome can be caused by bleeding in the pons or due to a lack of oxygen in the pons. These are often the result of strokes, tumours, infection, loss of insulation around the nerve cells, and atrophy disorders such as amyotrophic lateral sclerosis.

Symptoms

The symptoms of this condition are directly resultant from neurological changes, and are as follows:

• Reduced and/or absence motor functions (not complete paralysis)
• Reduced and/or absence of speech capabilities
• Reduction or absence of inhibition and emotions
• Apathetic movement and ever-present slowness

This condition can be misdiagnosed as a mental health illness such as depression, as well as locked-in syndrome. This is because the cases often present similarly, but correct diagnosis is important for adequate and effective treatment.

Locked in syndrome may present with the following symptoms:

• Inability to consciously chew or swallow
• Loss of ability to breathe
• Loss of ability to speak
• Unable to move in any way other than moving the eyes and eyelids

Potential causes

Akinetic mutism can the result of a stroke occurring in the thalamus of the brain, infections such as meningitis, trauma to the brain, acute encephalitis, a resultant condition of oxygen starvation to the brain, the occurrence of tumours and cysts, aneurysms, and central nervous systems infections.

Locked-in syndrome can occur as a result of the interruption in the motor fibre nerve message connection due to lack of blood flow to the pons or bleeding in the pons from a stroke, infection, or chronic conditions.

Treatment

Depending on the cause behind akinetic mutism, and the severity thereof, various treatment options may be explored. These include:

• Magnesium sulphate 
• Removal or draining of cysts causing the condition
• Dopamine therapy

In other cases, there is no viable treatment options for the patient.

Treatment for locked-in syndrome is generally aimed at targeting the underlying cause of the syndrome.

• If caused by a clot, then intraarterial thrombolytic therapy can be administered to reverse the clot
• Artificial breathing machines to assist in breathing in initial stages of the syndrome
• Infections may be treated with medication
• Chronic conditions such as tumours can be treated with steroids and radiation therapy

Degenerative conditions are usually treated with end-of-life support and palliative care

Table of comparison between akinetic mutism and locked-in syndrome

Summary

Akinetic mutism and locked-in syndrome are both rare neurological conditions with similar presentation but different causes and difference treatments. Although these conditions can be misdiagnosed, symptoms will differentiate them, and effective treatment is important for chance of survival.

FAQ

What is akinetic mutism?

Akinetic mutism is a rare and complex neurological disorder. Patients suffering from akinetic mutism are not able to maintain an intact consciousness, attention, or responsiveness level. This condition is associated with structural damage to a wide variety of areas in the brain and is particularly difficult to diagnose because owing to its complexity. 

What is locked-in syndrome?

Locked-in syndrome, or pseudocoma, is a condition characterized by a total and complete paralysis of all the voluntary muscle groups, except for muscles which control eye movement. This is due to damage occurring in the brain stem. Patients with this syndrome are conscious but are unable to communicate, with no standard course of treatment or cure available.

Is akinetic mutism a coma?

Akinetic mutism is not a coma but can easily be mistaken for one. Patients with akinetic mutism are fully awake and responsive with the ability to communicate but not through a suitable verbal response (sometimes present but significantly delayed) and usually void of emotions. Paralysis or coma are not accounted for symptoms of akinetic mutism.

Can you come out of locked-in syndrome?

Recovery from locked-in syndrome is unpredictable and highly variable, often dependant on the underlying cause. In cases where locked-in syndrome is acute, there is usually a high mortality rate. When receiving appropriate medical care, patients suffering from this syndrome can have a longer life expectancy, extending over decades. Survivors of locked-in syndrome could regain certain functions but, in most cases, they remain in a condition of minimal motor function with low levels of progress.

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