Hemiplegia is a symptom that involves one-sided paralysis. Hemiplegia affects either the right or left side of your body. It happens because of brain or spinal cord injuries and conditions. Depending on the cause, hemiplegia can be temporary or permanent. Some causes of hemiplegia are treatable or even reversible with immediate medical care.
Hemiplegia is paralysis that affects only one side of your body. This symptom is often a key indicator of severe or life-threatening conditions like a stroke, but can also happen with conditions and circumstances that aren’t as dangerous.
Hemiplegia is paralysis, which means you can’t move or control the muscles in the affected body part. That can cause muscles that are completely limp. It can also cause spastic hemiplegia, a type of paralysis where muscles contract uncontrollably. Hemiplegia affects either the right side of your body (right hemiplegia) or the left side of your body (left hemiplegia), with your spine (backbone) being the dividing line between the two halves.
Hemiplegia may affect your face, arm and leg on one side of your body in various ways: The paralysis may not be present, or not be as severe in all of these three body areas. There are even some rare conditions that cause hemiplegia to come and go, affecting one or both sides of the body as it does.
Depending on how and why it happens, hemiplegia may be treatable. In some cases, no treatment is necessary, while others need immediate medical care to reverse the cause of the hemiplegia.
IMPORTANT: Hemiplegia is a key sign of a stroke, which is a life-threatening medical emergency. To recognize the symptoms of a stroke, remember to think FAST:
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
Hemiplegia happens because of problems that affect your central nervous system (CNS). The two parts that make up your central nervous system are your brain and spinal cord. To understand how conditions cause hemiplegia, it helps to know a little bit about how your CNS works.
A key part of how your CNS works involves a concept known as “decussation.” This term comes from “decussis,” the Latin word for the Roman numeral “X.” Decussation means that nerves on opposite sides cross over each other (like an X) and switch sides. The place that happens is in your brainstem, just above where your skull and spine connect.
Decussation is why conditions on one side of your brain often affect the opposite side of your body. Healthcare providers call this “contralateral hemiplegia,” which means “opposite side paralysis.” When you have hemiplegia on the same side, the term is “ipsilateral hemiplegia.”
The only exceptions to decussation happen when the affected nerves don’t pass through the area of the brainstem where the nerve fibers switch sides. Because of this, hemiplegia happens differently depending on where in your CNS the problem starts.
There are dozens of conditions and circumstances that can cause hemiplegia. Some of the most common causes include:
The treatments for hemiplegia depend on the underlying cause. Some of these conditions are treatable or even curable. Others may get better on their own. Unfortunately, many of these conditions cause permanent damage to parts of your nervous system, such as spinal cord or traumatic brain injuries. In these cases, the hemiplegia won’t go away, although it may improve to some degree.
Because there are so many different ways to treat hemiplegia that a healthcare provider is the best person to tell you more about the possible treatments in your situation. They can give you information that considers your specific condition, circumstances, health history and more.
Hemiplegia is a key symptom of stroke, which is a life-threatening medical emergency. Because of that, you shouldn’t try to self-diagnose or self-treat it.
An exception to this is a condition where hemiplegia can happen temporarily, like migraines, or if you have permanent hemiplegia from another nonlife-threatening cause. In either of these cases, talk to your healthcare provider about your condition and its symptoms. They can tell you when hemiplegia is a sign that you need to seek medical attention immediately.
Hemiplegia often happens unpredictably. Because of that, there’s no way to prevent it entirely. However, you can reduce your risk of it by avoiding conditions or circumstances that can cause hemiplegia. Some steps you can take include:
When hemiplegia isn’t temporary, healthcare providers often recommend rehabilitation in addition to other treatments. Rehabilitation can take place in a hospital (inpatient rehabilitation), clinic or office (outpatient rehabilitation), or at home. Rehabilitation generally includes:
There’s ample evidence that exercise helps optimize health and the ability to function after hemiplegia. Exercising may be more challenging with hemiplegia. This is why rehabilitation therapists usually develop exercise programs adapted to a person’s needs and abilities.
Hemiplegia is almost always a reason to see a healthcare provider as soon as possible. The only exception is if you know you have a condition that causes hemiplegia (such as hemiplegic migraines) and your healthcare provider advises you on how to monitor and react to this symptom.
Hemiplegia and hemiparesis are similar in that they describe weakness on one side of your body, and they’re caused by the same conditions and injuries. Generally, hemiplegia refers to complete paralysis, while hemiparesis refers to partial weakness.
A note from Cleveland Clinic
Hemiplegia is a symptom that causes paralysis on one side — left or right — of your body. Because it’s a key symptom of a stroke, hemiplegia is almost always a reason to seek immediate medical care (unless you have a diagnosed condition that causes hemiplegia and your healthcare provider tells you that emergency care isn’t necessary).
Hemiplegia can often be frightening or alarming, especially if it happens unexpectedly. However, the most common cause of hemiplegia, stroke, is often reversible if a person gets medical care immediately. Many other causes of hemiplegia are also treatable or reversible, so it’s important not to delay medical care if you have it.
Last reviewed by a Cleveland Clinic medical professional on 07/23/2022.
Learn more about our editorial process.