What Are Hemiplegia and Hemiparesis

If you have had a medical problem that has caused part of your body to become weak, you may have paralysis, paresis, hemiparesis, or hemiplegia. Hemiplegia and hemiparesis are the terms used to describe a weakness that affects one side of the body.

A physical therapist working with her patient
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While these conditions both have symptoms of weakness, they are very different:

  • Hemiplegia and paralysis mean that the affected parts of the body are completely weak.
  • Hemiparesis and paresis mean that the affected parts of the body are only partially weak. With these conditions, there is some motor strength remaining in the weakened arm or leg.

This article explains what hemiplegia and hemiparesis are, their symptoms, causes, diagnoses, and treatment.

What Are Hemiplegia and Hemiparesis

Hemiplegia is paralysis that affects one side of the body. Hemiparesis is a weakness that affects one side of the body. To understand why these conditions result in weakness, you need to know how the brain and nervous system work.

The weakness often only affects half of the body because the human brain and the spinal cord each have two identical 'halves' on the right and the left side. Each of these halves controls the movement of only one side of the body.

The human brain contains a motor region called the motor strip that controls movement. In addition, the left and right sides of the cerebral cortex each contain a motor strip that controls the opposite side of the body.

Similarly, the spinal cord contains a region called the corticobulbar tract that controls physical movements. The left side controls one side of the body, and the right side controls the other.

Thus, an injury to one side of the brain or spinal cord produces left-sided hemiplegia, while an injury to the other side produces right-sided hemiplegia.

There are several variations of paralysis. They are classified as:

  • Partial – retaining some control of the muscles
  • Complete – inability to move any muscle
  • Permanent – muscle control does not come back
  • Temporary – some muscle control returns
  • Flaccid – muscles become flabby and may shrink
  • Spastic – muscles become stiff and may spasm

Symptoms

The most prominent symptom of hemiplegia and hemiparesis is weakness on one side of the body. In addition, you may experience the following with these conditions:

  • Loss of balance
  • Trouble walking
  • Difficulty grasping items
  • Muscle weakness
  • Lack of coordination
  • Stiff muscles
  • Difficulty swallowing

Causes

Muscle movement is controlled by signals sent to the body by the brain and spinal cord. When brain or spine damage occurs, the signals cannot direct the muscles to move, resulting in paralysis.

Most cases of hemiplegia occur as a result of a stroke. Other causes of hemiplegia include the following:

Diagnosis

Evaluation of hemiplegia and hemiparesis involves a physical exam. During the exam, your doctor will test your reflexes and muscle strength.

In addition, your doctor may order the following imaging tests and diagnostic procedures:

Weakness or loss of function in your limbs always requires immediate attention. If you experience muscle weakness or paralysis, seek medical attention right away.

Complications

Secondary conditions of hemiplegia and hemiparesis are problems that you might experience as a result of the weakness. Sometimes, these problems are not noticeable right away. Instead, they may develop months after you first notice hemiplegia.

Some of the complications of hemiplegia and hemiparesis include:

Treatments

Sometimes, muscle strength may improve on its own. In addition, hemiplegia may respond to treatment. Some treatments for hemiplegia include:

  • Physical therapy: Exercise is helpful to keep joints loose and flexible. Carefully designed therapy techniques prevent muscle atrophy (the loss or decrease of muscle mass) and spasticity. Physical therapy also helps prevent the complications of hemiplegia and hemiparesis - such as heart disease, diabetes, pressure sores, obstructive pulmonary disease, urinary tract infections.
  • Occupational therapy: This type of therapy focuses on learning how to take care of practical tasks and everyday activities, such as self-care.
  • Mobility aids: Mobility aids include manual and electric wheelchairs, scooters, braces, canes, and walkers. These aids can help you lead an independent, active life even if you have hemiparesis or hemiplegia.
  • Assistive technology: The use of voice-activated devices, computers, telephones, and lighting systems is becoming more available and practical to use.
  • Adaptive equipment: The use of specially designed devices for driving, eating, and personal hygiene can help in practical day-to-day activities.

Summary

Hemiplegia and hemiparesis are related conditions that cause weakness on one side of the body. Hemiplegia is when the weakness causes paralysis, while hemiparesis is partial weakness.

The cause of these conditions is varied but usually results from an injury or illness to the spinal cord or brain. Physical and occupational therapy can sometimes help people regain some mobility. Mobility aids and assistive technology help people remain independent and active.

A Word From Verywell

Hemiplegia and hemiparesis are difficult conditions to adjust to. But there are steps you can take to make living with hemiplegia or hemiparesis easier.

Neurological illnesses that cause hemiplegia and hemiparesis are not uncommon. Talk to your doctor about resources that can help you through your recovery. They will be able to direct you to resources that can provide support with practical aspects of life.

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