What to know about locked-in syndrome

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Locked-in syndrome is a rare neurological disorder that occurs due to damage in the brain stem, typically the pons.

It involves:

• complete paralysis of voluntary muscles (paraplegia)
• whole body sensory loss
• functional impairment of the lower cranial nerves (bulbar palsy)
• loss of horizontal eye movements (left and right eye movements)

People with locked-in syndrome are conscious, alert, and awake. They have regular sleep-wake cycles and retain their ability to reason and think (cognitive function).

They can also see and hear. The inability to move their lower face prevents them from showing facial expressions. However, they retain their ability to blink and move their eyes up and down, allowing them to communicate through purposeful eye movements.

What is the brain stem?

The brain stem is a stalk-like structure that connects the cerebrum to the spinal cord and cerebellum. It has three parts:

• midbrain
• pons
• medulla

The structure is responsible for vital body functions, such as breathing and consciousness. It also contains a critical collection of gray matter and white matter.

Damage to some brain stem regions that conditions such as stroke and tumors cause can lead to locked-in syndrome.

Learn more about the parts and functions of the human brain.

People with locked-in syndrome may initially be in a coma before slowly regaining consciousness. However, they remain paralyzed and unable to move or speak. They are often bedridden and rely entirely on their caregivers.

Generally, a person with locked-in syndrome cannot voluntarily or consciously:

• move their limbs
• move their lower face
• breathe
• chew and swallow (dysphagia)
• speak (anarthria)
• move eyes laterally (left to right)

Other symptoms can also include:

• breathing stops and starts (apnea)
• deeper breaths than usual (hyperpnea)
• poor muscle control (ataxia)
• dizziness
• vertigo

There are three forms or types of locked-in syndrome based on the number of motor abilities preserved. This depends on the severity of damage to the neuronal tracts that pass along the brain stem.

These types include:

• Classical form: It involves total immobility with the preserved ability to blink and perform vertical eye movements.
• Incomplete form: It is similar to classical form, but the person keeps some voluntary movements other than the eye movements. Survival rates are also better.
• Total immobility form: There is a total loss of motor functions, rendering a person unable to express their thoughts and needs.

Locked-in syndrome often happens due to damage in the central area of the pons. The anterior pons is a horseshoe-shaped mass of fibers that connects the cerebral cortex to the medulla.

Tissue damage disrupts the motor fibers that run from the brain to the body through the spinal cord. It can also occur in the areas in the pons that are important for speaking and facial muscle control.

The most common causes of lesions in the pons and other areas of the brainstem include:

• Vascular: Strokes caused by lack of blood flow (ischemic stroke) or bleeding (hemorrhagic stroke) are the most common cause of locked-in syndrome.
• Trauma: Traumatic brain injuries from blunt or penetrating trauma are the second leading cause of locked-in syndrome.
• Mass: Tumors can grow in the anterior pons or midbrain area and lead to locked-in syndrome.
• Infections: Rarely, locked-in syndrome can occur secondary to the spread of infection to the brain stem. Examples include pseudomonas and meningitis. A 2020 study reported a case of a person developing locked-in syndrome due to COVID-19.
• Demyelination: Certain conditions that cause demyelination (damage to the outer covering of nerve fibers in the brain) can lead to locked-in syndrome. Examples include multiple sclerosis (MS), central pontine myelinolysis (CPM), and amyotrophic lateral sclerosis (ALS).

Locked-in syndrome is slightly more common in males than females and occurs mostly in adults ages 30 to 50 years.

People at risk of stroke and bleeding in the brain are also at risk of developing locked-in syndrome. These include people with the following conditions:

• hypertension
• atherosclerosis
• diabetes

Doctors make a diagnosis of locked-in syndrome clinically. They request and review a person’s health history to identify the possible cause of the condition. They will also perform a clinical evaluation consisting of a physical and neurological exam to assess cranial nerve function.

They may also order tests to rule out other possible conditions to help diagnose locked-in syndrome.

These include:

• imaging tests, such as CT scans and MRI
• laboratory tests, such as cerebrospinal fluid (CSF) analysis
• electrophysiologic studies, such as nerve conduction studies and electroencephalogram (EEG)
• blood tests, such as sodium levels

The initial goal of treatment is to address or reverse the underlying cause of locked-in syndrome, such as stroke. Healthcare professionals will also ensure that the person is stable and has adequate blood and air supply.

A person with locked-in syndrome may also need a tracheostomy tube for breathing and a gastrostomy tube for feeding and drinking.

The next aims of treatment include:

• establishing communication via speech therapy and the use of assisted technology
• maintaining voluntary respiratory muscle function through physical therapy
• early rehabilitation of small voluntary movements

Many doctors find it challenging to diagnose locked-in syndrome since it has a similar presentation with other medical states, including:

• coma
• persistent vegetative state
• akinetic mutism
• catatonia
• brain death
• cervical spinal cord injury (SCI)

Other conditions can show similar symptoms of total paralysis with intact cognition. These include:

• Amyotrophic lateral sclerosis (ALS), but this condition progresses slower than locked-in syndrome
• Guillain-Barré syndrome (GBS)
• critical illness polyneuropathy

People with a higher risk of stroke may have a greater likelihood of developing locked-in syndrome. While most cases are not preventable, a person may talk with their doctor about ways to lower their risk.

The outlook for people with locked-in syndrome depends on the condition’s cause and the level of support the person receives.

The survival rate of locked-in syndrome has improved greatly over the years, with a reported 80% of people living 10 years after the onset of the disease. The early recovery of the following features predicts a favorable outlook:

• left and right (lateral) eye movements
• electrical activity in the motor cortex (the brain area responsible for controlling voluntary movements) in response to magnetic stimulation

People with locked-in syndrome due to reversible causes like transient stroke and GBS may have partial to complete recovery. Meanwhile, irreversible and progressive disorders like cancer are usually fatal.

Based on a 2015 study, it is also possible for most people with chronic locked-in syndrome to recover non-eye-dependent communication and some functional movement.

One case study noted that many people with locked-in syndrome report satisfactory quality of life, despite living with a significant disability.

However, a 2021 review reported that the condition has a poor outlook and that many people have a poor quality of life, especially concerning motor function.

Promoting autonomy and preserving communication for people with locked-in syndrome may help them live with as much control as possible.

A lot of progress has been made in developing assistive technology for people with locked-in syndrome, allowing them to interact with others. Electronic communication devices can scan the eye movements of patients with ALS and enable them to communicate in some form.

In a 2015 study, around 60% of people with locked-in syndrome stated they were able to use an electric-powered wheelchair, which gave them some autonomy.

Locked-in syndrome is also associated with complications, including infections, pneumonia, and urinary tract infection (UTIs). Caregivers can work with a medical team to help prevent these complications and improve outcomes.

Here are some answers to frequently asked questions about locked-in syndrome.

Can you get out of locked-in syndrome?

Recovery from locked-in syndrome depends on its underlying cause. Partial to complete recovery is possible for reversible causes, such as Guillain-Barre syndrome and transient stroke.

However, according to a 2021 review, most people with the condition only regain a small amount of capacity.

While full recovery is unlikely, a 2015 study found that most people with locked-in syndrome recovered some functional movement and non-eye-dependent communication over time.

How long does locked-in syndrome last?

There is no cure for locked-in syndrome. It’s a lifelong condition for most people.

Locked-in syndrome also has a high mortality rate in acute settings. However, many people with locked-in syndrome lead meaningful lives and live for 10 to 20 years.

Locked-in syndrome is a rare neurological condition characterized by complete paralysis of the body and facial muscles while maintaining intact consciousness and cognition.

Many doctors find it challenging to diagnose locked-in syndrome since it has a similar presentation to other medical states like a coma.

The outlook for people with locked-in syndrome depends on the underlying cause and the level of support they receive.

While full recovery is not common, many people with the condition can still lead meaningful lives and have a satisfactory quality of life. Developing ways to communicate may help them live with as much autonomy as possible.

Coordinating with the medical team to prevent infections and other complications associated with locked-in syndrome is essential.