There are several different ways that a stroke can affect the muscular system. In this article, you will learn some of the most common muscle function changes that can occur after stroke and why they happen. Then, we will cover some of the best ways to treat these changes.
How Does a Stroke Affect the Muscular System?
The brain controls both involuntary and voluntary muscular activity by sending neural messages to the muscles. These messages primarily originate in the motor cortex, which is found in the frontal lobe of the brain.
The motor cortex transmits these signals to the spinal cord, where they can reach the motor neurons. When these neurons fire, the impulse travels from it to the specific muscle, telling the muscle to contract or relax.
When a stroke occurs, this complex process can be disrupted, which can result in changes in muscle function. Depending on the severity and location of the stroke, this can often lead to changes in muscle tone and function.
In the following sections, we will discuss the most common ways that a stroke can affect the muscular system.
Changes in Muscle Function that Occur After Stroke
A stroke can have a damaging effect on a variety of muscle groups. These effects can range from mild to severe, and rehabilitation can help individuals recover movement.
The following are a few common examples of muscle function changes that can occur after a stroke:
1. Hypotonia (Low Muscle Tone)
Hypotonia refers to low or decreased muscle tone due to extended periods of inactivity.
All muscles will lose strength and tone if you do not move them regularly. For example, someone with a cast on their arm for a few weeks can lose muscle mass on that arm. This also applies after a stroke.
There are multiple reasons why you might experience hypertonia after stroke. Three of the most common include:
- Learned non-use. Stroke often causes weakness or paralysis on one side of the body. This weakness can lead to learned non-use, a condition where your brain loses its connection to your muscles. As a result of the lack of communication, the person may cease to use their affected arm. If the patient does not use their arm for an extended period, their muscles can begin to atrophy.
- Prolonged hospitalization. If a stroke was severe, the patient may need to remain in the hospital for several weeks. This prolonged inactivity can cause muscles to deteriorate.
- Malnutrition. Finally, stroke can cause difficulties with chewing and swallowing food (also known as dysphagia). This can lead to malnutrition which, if combined with inactivity, can speed up hypotonia.
As you can see, stroke causes a number of factors that can lead to muscle loss. Therefore to reverse muscle atrophy, you will need to address these underlying causes.
2. Hypertonia (High Muscle Tone)
Hypertonia refers to a high amount of muscle tone and increased tension in the muscles. It typically occurs when a stroke damages the part of the brain that sends inhibitory signals to the muscles. These signals instruct the muscles to relax when necessary.
As a result, the muscles continuously fire, causing extreme tension. Usually, hypertonia affects a patient’s arm, leading it to pull in and flex towards the body. It also commonly affects the hand, causing the affected hand to clench into a fist.
If hypertonia persists for too long, a joint deformity known as contractures can develop. Contractures occur when muscle fibers shorten and become stiff. This causes a decrease in range of motion and a restriction of function.
The most common areas that contractures can affect include the hips, elbows, and knees. Most patients develop contractures in two or more joints. Typically they occur in the areas where hypertonia is most severe.
Spasticity is a type of hypertonia that often appears after a stroke. This disorder is associated with increased activity of the muscle stretch reflex. The muscle stretch reflex (myotatic reflex) is a contraction that occurs in response to stretching within the muscle.
When you stretch a muscle, its nerve activity increases. The increased activity triggers a contraction in the muscle fibers in order to resist the stretching. This prevents muscles from stretching too far and tearing.
This reflex is controlled by the central nervous system. Normally, the muscles and the brain communicate with each other in a constant exchange of information. This allows the brain to know when to contract the muscles and when to release them.
However, after a stroke, this communication is often disrupted, which leads to an imbalance of signals in the muscles. As a result, the muscle reflex never deactivates, and the muscles stay in a constant state of flexion. This state is what doctors call spasticity.
4. Hemiplegia and Hemiparesis
If a stroke completely severs the connections between the brain and the muscles, stroke paralysis (hemiplegia) can develop.
Because strokes typically only affect one side of the brain, paralysis also typically occurs on one side of the body. For example, if the left side of the brain sustains damage, the right side of the body may become paralyzed. Doctors refer to paralysis on one half of the body as hemiplegia.
Hemiplegia occurs because each side of the brain controls movement on the opposite side of the body. However, when a stroke damages these areas of the brain, those signals can become weakened or lost. As a result, the muscles are not able to respond to the brain’s directions, and paralysis can set in.
Fortunately, if the connection is simply damaged but not lost, some neural signals can still pass to the muscles. As a result, muscle activation will be significantly weaker, but still possible. This condition is known as hemiparesis.
How to Restore Muscle Function After Stroke Through Neuroplasticity
Neuroplasticity refers to the brain’s natural ability to reorganize nerve cells and form new neural pathways. These new pathways in turn allow healthy, undamaged portions of the brain to take over control from damaged areas.
To activate neuroplasticity, you must engage in consistent, therapeutic exercise. The more you practice an activity, such as moving your arm, the more it reinforces new neural pathways. And the more you strengthen those pathways, the stronger the connection between your brain and muscles will become.
However, this poses a dilemma for stroke patients with hemiplegia or other disorders in muscle function. To recover their movement, patients must engage neuroplasticity, but to engage neuroplasticity, patients must move their muscles. Fortunately, there are other ways to activate neuroplasticity that do not require active movement.
The Benefits of Passive Range-of-Motion Exercise
Passive range-of-motion exercises are an effective way to activate neuroplasticity when it is difficult to move on your own. With this technique, a therapist moves your affected arms and legs for you. As simple as this sounds, it will significantly aid your stroke recovery.
In fact, recent research shows that passive movement activates the same parts of the brain that active movement doe. It can even trigger neuroplasticity. This can reestablish communication with your brain and muscles, which can further reduce paralysis and spasticity and increase muscle function. Eventually, you might even recover enough strength to move on your own again.
In addition, passive range-of-motion exercises also keep your muscles flexible and can therefore prevent contractures from setting in. This makes it critical for preventing further loss of muscular function after stroke.
The Importance of Active Exercise at Home
The more you engage in passive exercise, the stronger the connection between your brain and muscles should become. When this connection is strong enough, you can begin to regain minimal movement in your affected limb. Once you can move a bit, you must engage in repetitive, active exercises to continue strengthening those neural pathways.
As you practice these repetitions, you can trigger substantial changes in your brain, which can help you regain further function. Therefore, if you want to recover muscle function after stroke, you must focus on high repetition.
One of the best ways to get fast results is to try Flint Rehab’s FitMi home therapy device. This device can help you accomplish the high repetition necessary to see improvement. In fact, FitMi helped a stroke survivor with arm paralysis experience twitches in his affected arm for the first time after three weeks of daily FitMi use.
Understanding How a Stroke Affects the Muscular System
A stroke can cause a wide range of problems within the muscular system, depending on its severity and location.
Fortunately, thanks to the brain’s natural neuroplasticity, it is possible to regain muscle strength and function after stroke. The key is to engage in regular and intensive physical therapy. If that is not possible, passive range-of-motion exercises can help activate the brain as well.
With enough hard work, you can begin to see progress in your stroke recovery. Eventually, you might even overcome the effects it has had on your muscles.
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