Causes of Locked-In Syndrome

Locked-in syndrome can occur from any injury or illness that affects a specific part of the brain. Below, our locked-in syndrome lawyers discuss the potential causes and the care people with locked-in syndrome often need.

How Locked-In Syndrome Can Occur

Locked-in syndrome (LIS) happens when there is damage to the pons. The pons is a part of the brainstem, a part of the body that connects the brain to the spinal cord and controls breathing, sleep-wake cycles, movement, pain signals, and balance.

Several things can damage the pons and cause locked-in syndrome.

Ischemic Stroke

Stroke is the most common cause of locked-in syndrome. Ischemic stroke and hemorrhage together cause the majority of cases, according to StatPearls. According to the meta-analysis:

• One study looked at 139 cases of locked-in syndrome and found that 105 of them were caused by problems with blood vessels, like stroke.
• A separate survey by the Association of Locked-in Syndrome of France found that 86.4% of the people surveyed said stroke caused their condition.

According to the Cleveland Clinic, a stroke that affects certain pathways in the brainstem, called the corticospinal, corticopontine, or corticobulbar tracts, is the most common cause of LIS.

An ischemic stroke happens when blood flow to part of the brain is blocked. In the case of LIS, this blockage cuts off blood flow to the pons. When something goes wrong with the arteries that feed the pons, it can lead to locked-in syndrome. Because the brainstem carries messages between the brain and the rest of the body, damage to it can cause the near-total paralysis that is the hallmark of LIS.

People with high blood pressure, hardening of the arteries (atherosclerosis), or an irregular heartbeat (atrial fibrillation) may have a higher risk of the kind of stroke that leads to LIS, according to StatPearls.

Hemorrhage

A hemorrhage is bleeding in or around the brain. It can cause LIS by directly destroying tissue in the brainstem or in the areas surrounding it. Hemorrhage can also lead to stroke, which, as noted above, is the most common cause of locked-in syndrome.

Traumatic Brain Injury

Traumatic brain injury is the second most common cause of locked-in syndrome, after vascular causes like stroke and hemorrhage, per StatPearls. LIS can happen if a head injury damages the brainstem directly or puts pressure on it.

This kind of injury can come from a blunt hit to the head or from a penetrating injury, such as a wound that tears or blocks the arteries that supply blood to the brainstem. In one reported case, a person developed LIS after a trauma even though there was no direct physical damage to the brainstem itself. Instead, swelling and pressure from the injury pressed on the brainstem and caused the same effect, according to StatPearls.

Central Pontine Myelinolysis (Osmotic Demyelination Syndrome)

Central pontine myelinolysis (CPM), also called osmotic demyelination syndrome, is another cause of locked-in syndrome. CPM damages myelin, which is the protective coating around nerve cells in the pons, according to the Cleveland Clinic.

CPM most often happens when sodium levels in the blood rise too quickly. This usually occurs while a patient is being treated for low sodium levels, called hyponatremia. Conditions that can lead to low sodium in the first place include:

• Alcohol use disorder
• Liver transplant
• Severe nausea and vomiting during pregnancy
• Malnutrition
• Burns

When sodium rises too fast, water is pulled out of nerve cells, causing them to shrink and become damaged. Nerve cells in the pons are especially vulnerable to this kind of injury. In severe cases, this damage can cause paralysis of all the muscles except those that control the eyes.

Doctors have described real cases of this happening. In one report, a 44-year-old man’s sodium level was corrected from 118 mEq/L to 134 mEq/L within just 18 hours. About a week later, he developed weakness that progressed to complete paralysis of his arms and legs; only the ability to blink remained. Brain imaging confirmed locked-in syndrome caused by CPM. Correcting sodium levels too quickly raises the risk of this kind of damage.

Unlike some other causes of LIS, recovery from CPM-related locked-in syndrome is sometimes possible with intensive, long-term rehabilitation.

Other Causes

Locked-in syndrome can also result from:

• A lesion or tumor on the brain stem
• Poisoning, often when the poison cannot cross the blood-brain barrier
• Snake bites or other bites involving neurotoxic venom
• Overdoses

Does the Cause of Locked-In Syndrome Affect the Type Someone Is Diagnosed With?

Doctors classify locked-in syndrome into three types, based on how much movement and function a person has left, not based on what caused the condition. The three types of LIS are:

• The classical form includes total immobility, but the person can still move their eyes up and down, blink, and think normally.
• The incomplete form is similar to the classical form, but with some added movement or sensation still present.
• The total immobility form includes complete body paralysis, including loss of eye movement. Cognitive function is still present, but it can only be confirmed through tests that measure brain waves, since the person cannot blink or move their eyes to communicate.

These categories describe the degree of paralysis a person has, not the specific illness or injury that caused it. Any of the causes described earlier can potentially result in any of the three types, depending on how much damage occurs and exactly where in the pons it happens.

Why the Cause Still Matters

Even though the cause doesn’t determine which “type” a person is labeled with, it can be connected to how severe the condition is and how well someone may recover.

• Vascular causes (stroke and hemorrhage) tend to have worse outcomes. One study published in the Annals of Rehabilitation Medicine found that recovery is generally slower and less complete when locked-in syndrome is caused by a vascular event, compared to a non-vascular cause.
• Non-vascular causes, such as central pontine myelinolysis, have been linked to faster and more complete neurologic recovery in some patients. For example, one patient with locked-in syndrome caused by CPM was able to regain the ability to move against gravity and walk with supervision after more than two years of rehabilitation.

Doctors also use the cause of a person’s locked-in syndrome to guide treatment, which can shape recovery. For example:

• Stroke-related LIS may be treated with clot-dissolving (thrombolytic) therapy.
• Tumors or masses pressing on the pons may be surgically removed.
• Infections like meningitis or abscesses can be treated with antibiotics.
• CPM is treated by slowly correcting sodium levels and closely watching breathing.

How Doctors Determine Type and Cause

Regardless of the underlying cause, doctors use similar tools to figure out both what type of locked-in syndrome a person has and what caused it, including MRI or CT scans of the brain, physical exams that test motor function and reflexes, and EEG (a test of brain wave activity) to check for consciousness in cases where no movement is possible.

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Treatment and Care for Patients With Locked-In Syndrome

There is no known cure for locked-in syndrome that occurs because of damage to the brain stem, poison or venom, or other illness or injury. Those who receive this diagnosis generally do not recover motor function. Their doctors offer support for breathing, hydration, and nutrition, and work to prevent further injuries such as bed sores.

While there is no cure and typically no way to recover lost motor function, there are many types of assistive equipment that can make everyday life easier on the person and their family. Lifts, hospital beds, and power wheelchairs make it possible to get out of bed and experience the world, while communication tools make it possible to talk about it.

Technology has and will likely continue to improve the quality of life for those with locked-in syndrome. This includes:

• Eye gaze devices
• Brain-computer interfaces
• Other communication and mobility devices

Pursuing Compensation for Locked-In Syndrome

Locked-in syndrome is not always preventable, but getting an accurate diagnosis and medical assistance is key in maintaining the quality of life. In some cases, your family may be eligible to pursue compensation through a medical malpractice or personal injury case with the help of a locked-in-syndrome lawyer. This may be true if:

• Your family member suffered locked-in syndrome following a stroke or other medical emergency that did not receive prompt diagnosis and treatment.
• Your loved one’s locked-in syndrome occurred because of a surgical or medical error.
• Your loved one’s doctor failed to diagnose locked-in syndrome when other doctors would have identified it earlier.
• Your loved one suffered a brain injury and locked-in syndrome because of another type of negligence accident.

If your family member has a locked-in syndrome diagnosis, let the team from Newsome Law review your case. We can explain your loved one’s rights and your options for pursuing compensation. Our case reviews and consultations are always free.

If you qualify, we can take legal action on your behalf, going after the damages your family deserves to help you cover ongoing care costs and other expenses. This may include:

• Medical treatment
• Ongoing and future care costs
• Lost wages
• Diminished earning capacity
• Out-of-pocket costs
• Pain and suffering
• Mental anguish

Moving Forward After a Locked-In Syndrome Diagnosis

Locked-in syndrome brings overwhelming challenges, but understanding its causes can help families make sense of a difficult diagnosis and consider what options may be available. If you have questions about the care your loved one received, we can help you find the answers.

Newsome Law offers free, no-pressure consultations to help you explore next steps.

Read more about Rich Newsome

Rich Newsome

Catastrophic Injury Locked-In Syndrome Attorney

Rich Newsome is a dedicated attorney specializing in catastrophic injury and medical malpractice cases. With over 25 years of experience, she is committed to advocating for victims and their families, ensuring they receive the justice and compensation they deserve.