Locked-in Syndrome (LiS)

Locked-in Syndrome (LiS)

Overview

Locked-in syndrome (LiS) is a rare neurological disorder characterized by paralysis of voluntary muscles, except for those that control your vertical eye (up and down) movements. People with locked-in syndrome are conscious, alert and have their usual cognitive abilities (thinking and reasoning), but they’re unable to show facial expressions, speak or move.

People with LiS can hear and typically communicate through purposeful eye movements, blinking or both. They can also use assistive technologies to communicate.

Locked-in syndrome is caused by damage to a specific part of your brainstem known as the pons.

Types of locked-in syndrome

Locked-in syndrome (LiS) has three main types, or forms, including:

The classical form: In this type of LiS, you have total immobility (lack of voluntary movement) but can move your eyes vertically (up and down), blink and maintain your usual cognitive abilities. You can also hear.

The incomplete form: This type of LiS is just like the classical form except you can have some sensation and movement functions in certain areas of your body.

The total immobility form: In this type of LiS, you have complete body paralysis and loss of eye movement, but you have your normal cognitive abilities. Healthcare providers can tell a person with this form still has cognitive (thinking and reasoning) function by examining cortical function with an electroencephalogram (EEG), a test that measures brain waves.

Symptoms

The effects of locked-in syndrome (LiS) on your body vary slightly depending on which type you have.

People with locked-in syndrome are often initially thought to be in a coma before recognition of consciousness.

Most people with locked-in syndrome cannot consciously or voluntarily:

Chew.

Swallow.

Speak.

Make facial expressions.

Produce any body movements below their eyes.

Most people with locked-in syndrome can:

Move their eyes up and down (vertically) but not side to side (horizontally, or laterally).

Blink.

All people with locked-in syndrome can:

Hear.

Comprehend people talking or reading to them.

Think and reason as they did before having locked-in syndrome.

Have sleep-wake cycles.

Depending on which form of locked-in syndrome (LiS) you have, you may or may not be able to feel physical pain.

If you have the total immobility form of LiS, you won’t be able to feel physical pain due to total paralysis of your body.

If you have the incomplete form of LiS, you may be able to feel physical pain and other sensations in certain areas of your body.

Causes

Locked-in syndrome (LiS) is caused by damage to a specific part of your brainstem called the pons.

The pons is a broad horseshoe-shaped mass of nerve fibers that connects the medulla oblongata (the lowest portion of your brainstem) with the cerebellum (a part of your brain that plays a vital role in virtually all physical movement, particularly coordination).

The pons contains important neuronal pathways between your cerebrum, spinal cord and cerebellum. In locked-in syndrome, damage to your pons results in interruption of all the nerves running from your brain, through your spinal cord and to your body’s muscles. This results in body paralysis. The damage to your pons also affects the centers in your brainstem that are important for facial control and speaking, which prevents you from making facial expressions, chewing, swallowing and talking.

Several specific conditions and situations can damage your pons, causing locked-in syndrome. The most common cause is ischemic or hemorrhagic stroke affecting the corticospinal, corticopontine and corticobulbar tracts in your brainstem.

An ischemic stroke happens when a blood vessel in your brain develops a blood clot and cuts off the blood supply to your brain. A hemorrhagic stroke happens when blood from an artery suddenly begins bleeding into your brain.

Other less common causes of damage to your pons that can lead to locked-in syndrome include:

Infection in certain portions of your brain.

Tumors or masses on your pons or brainstem.

Demyelination, which is the loss of the protective insulation (myelin) that surrounds nerve cells.

Certain conditions, such as amyotrophic lateral sclerosis (ALS) and Guillain-Barre syndrome.

Trauma (injury) to your pons.

Substance misuse.

Diagnosis

As people with locked-in syndrome (LiS) lack motor responses (such as withdrawal from painful stimulation), which healthcare providers use to measure responsiveness, healthcare providers may mistakenly think people with LiS are unconscious. Because of this, LiS can be difficult to diagnose or take a while to correctly diagnose.

A significant aspect of an LiS diagnosis is ruling out other conditions that could be causing your symptoms. Healthcare providers also need to determine the cause of locked-in syndrome as a part of the diagnosis and treatment.

Healthcare providers use several tests to help diagnose locked-in syndrome, determine the cause and rule out other possible conditions.

These tests include:

Magnetic resonance imaging (MRI) scan or computed tomography (CT) scan: An MRI or CT scan can show if you have damage to your pons and/or other portions of your brain.

Cerebral angiography: This test can reveal if you have a blood clot in the arteries of your brainstem or somewhere else in your brain.

Electroencephalogram (EEG): This test measures the electrical activity of your brain. It can help healthcare providers determine if you’re experiencing normal brain activity and sleep-wake cycles, which distinguishes LiS from other conditions.

Evoked potentials: These are tests that measure the electrical activity in certain areas of your brain and spinal cord in response to stimulation, such as pain, auditory or visual stimulation. Healthcare providers use these tests to assess the damaged responses in your brainstem and the preserved responses in your brain.

Electromyography: This test measures how well your muscles and nerves work. Healthcare providers may use this test to rule out damage to your muscles and nerves.

Blood tests: A metabolic panel, particularly checking blood sodium levels, can help determine if pontine myelinolysis is the cause.

Cerebrospinal fluid (CSF) examination: This test can help determine if an infection or autoimmune condition is causing your symptoms.

Treatment

There is no cure or specific treatments for locked-in syndrome other than treating the cause and preventing further complications, if possible.

Management of locked-in syndrome includes supportive therapy and communication training.

Supportive therapy

Supportive therapy for breathing and feeding is very important, especially early on. People with locked-in syndrome (LiS) often need an artificial aid for breathing and will have a tracheotomy (a tube going in their airway through a small hole in their throat).

Because eating and drinking using your mouth isn’t safe with LiS, people with LiS usually have a small tube inserted in their stomach called a gastrostomy tube (G-tube) to receive food and water.

Other supportive therapies include:

Preventing complications due to immobilization, such as pneumonia, urinary tract infections (UTIs) and thrombosis.

Preventing pressure injuries (bedsores).

Providing physical therapy to prevent limb contractures (lack of range of motion due to joint, muscle or soft tissue limitations).

Providing physical therapy for rehabilitating the small voluntary movements that remain or recover, if any.

Communication training

Speech therapists can help people with locked-in syndrome (LiS) communicate more clearly with eye movements and blinking. The method of communication is unique to each person. For example, looking up could mean “yes” and looking down could mean “no” or vice versa. People with LiS can also form words and sentences by signaling different letters in the alphabet while someone else verbally lists each letter.

In addition to coded eye movements for communication, electronic communication devices, such as infrared eye movement sensors and computer voice prosthetics, allow people with locked-in syndrome to communicate more freely and have access to the internet

Type of Doctor Department : A neurologist