What Is Paresis?

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Paresis is a condition where the muscles in an area of the body become weaker and difficult to move voluntarily. This issue, which can obviously have an enormous impact on your daily function, is actually a symptom of an underlying disorder. In fact, a wide variety of diseases and injuries can lead to motor function deficits in your body.

For a comprehensive review of paresis and its various causes, take a look at the sections below.

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Paresis vs. Paralysis

Before going in-depth on paresis, it is important to differentiate it from another condition called paralysis. While these two issues can cause similar symptoms, there are important differences between them.

  • Paresis causes weakness in an area of the body (like an arm or leg). While this condition can make an area of the body difficult or fatiguing to move, there is still some motor function present.
  • Paralysis is the complete loss of motor function, and the person is unable to move the affected body region in any capacity. The paralyzed muscle groups will not contract or fire, and even a flicker of activation is unable to be seen. This typically occurs because of damage to the brain, spinal cord, or nerves, each of which helps initiate movement by relaying messages to the muscles.

Types of Paresis

There are several different types of paresis. These varieties are typically named for the number of regions that are impacted by weakness.

The most commonly seen versions of the condition are:

  • Monoparesis: Weakness in just one extremity, like an arm or leg.
  • Diparesis: A body region on both sides of the body, such as both legs or both sides of the face, is afflicted with weakness.
  • Paraparesis: Weakness in both legs (and sometimes a portion of the trunk).
  • Hemiparesis: Weakness affecting both the arm and the leg on one side of the body.
  • Double Hemiparesis: Both arms and legs are weak, with one side of the body being more affected than the other.
  • Triparesis: Weakness impacting three of the four extremities of the body (e.g., both legs and one arm).
  • Quadriparesis: Also known as tetraparesis, this refers to weakness in all four extremities of the body.
  • Pentaparesis: All four limbs and the head or neck are affected by weakness.

Causes

As mentioned previously, there are many different conditions that can lead to paresis. In most cases, however, the underlying issue occurs in a separate location from the weak area (or areas) of the body.

Causes of paresis can include:

  • Stroke: This is one of the most common reasons for paresis. This issue occurs when the blood flow to an area is interrupted by a blockage or rupture in the blood vessel. Strokes in either the brain or spinal cord can lead to the development of weakness in the face or extremities.
  • Injuries to the spinal cord: These can occur after a traumatic car crash or fall and can also cause similar motor issues.
  • Seizure: A disorder called Todd’s paresis can cause one or both sides of the body (usually in the extremities) to be temporarily afflicted by weakness.
  • Cerebral palsy: This occurs as a result of damage to a child’s brain, usually while in utero or during labor.

In the case of more localized paresis, several other issues may be to blame, including:

  • Bell’s palsy: An autoimmune condition with unknown origins, it can lead to temporary drooping and paralysis on one side of the face.
  • Viral infections or surgery in the throat: These can also cause paresis of the vocal cords.
  • Damage to your vagus nerve (a long nerve running from the face to the abdomen): This can also lead to gastroparesis, a condition in which the stomach becomes partially paralyzed and is unable to effectively empty food. 

Finally, several other neurological or bacterial issues are potential causes, some rarer than others.

Conditions that can lead to paresis include:

Additionally, an untreated syphilis infection that lingers over many years can also eventually affect the brain (called neurosyphilis) and cause something called general paresis. In spite of its name, this variety of the condition exclusively causes mental and cognitive impairments. 

Symptoms

Most of the issues that lead to paresis occur in the brain or spinal region. Because of this, a wide variety of other symptoms can occur along with the loss of motor function.

In the case of a spinal cord injury, paresis can be accompanied by:

  • Breathing or digestive issues
  • Loss of bowel or bladder control
  • Sexual dysfunction
  • Difficulties regulating your heart rate

After a stroke, symptoms can include:

  • Bowel or bladder incontinence
  • Numbness and tingling in the extremities
  • Slurred speech
  • Facial drooping
  • Difficulty feeling hot or cold temperatures

In people with cerebral palsy, issues can include the:

  • Bowel
  • Bladder
  • Digestive system

Along with this, cognitive or intellectual impairments, vision or hearing problems, seizures, and chronic pain may also be present.

Individuals with multiple sclerosis tend to experience symptoms that can flare up at times and then go into periods of remission. During a relapse, the paresis may be accompanied by:

  • Blurred or double vision
  • Extreme fatigue
  • Tingling or pain throughout the body
  • Bowel or bladder incontinence
  • Dizziness

Finally, more localized forms of paresis can often have other symptoms in the affected area. For example, Bell’s palsy can cause:

  • Facial numbness
  • Tearing
  • Drooling
  • Loss of taste
  • Hypersensitivity in the affected ear

Along the same lines, vocal cord paresis can cause a soft, hoarse, or whispery-sounding voice along with pain or breathlessness while speaking.

Because each case of paresis is unique, it is important to stay in communication with a physician about your symptoms.

Diagnosis

Because of the many potential causes of paresis, diagnosing the underlying issue can be quite tricky.

A thorough evaluation by a neurologist is a crucial step in this process. Typically, your doctor will take you through a comprehensive examination focusing on your:

  • Muscular strength and movement
  • Neurological system and reflexes
  • Mental function

Imaging, like an X-ray, MRI, or CT scan, may also be needed to look for any physical damage in the brain, spine, or blood vessels. In addition, blood draws may be needed to assess certain lab values that can be indicative of a potential paresis-causing condition. 

Treatment

Once the cause of your paresis has been properly diagnosed, your doctor can outline the treatment options at your disposal.

  • Paresis caused by an obstructive stroke can be greatly improved or resolved if treated quickly with a medication called tissue plasminogen activator (t-PA) that helps clear a blood vessel blockage.
  • In the case of a hemorrhagic stroke, early surgery to support a ruptured area can also lead to significant improvements.
  • More specialized types of paresis, like vocal cord paresis or Bell’s palsy, may self-resolve or may be improved with the help of therapy, injections, or even surgery.

Unfortunately, many types of paresis have no cure. The weakness caused by cerebral palsy, more severe strokes, or a spinal cord injury is usually permanent. As a result, therapy and assistive devices are typically needed to maximize an individual’s independence and make daily tasks more manageable.

This same treatment strategy is also utilized for more progressive conditions, like multiple sclerosis or ALS. The progression of the paresis from these debilitating issues may also be slowed with the help of certain medications. 

Summary

Paresis—a condition where the muscles in an area of the body become weaker and difficult to move voluntarily—is generally a symptom of an underlying disorder. Uncovering the root of paresis will ultimately bring you to a treatment plan.

A Word From Verywell

Coping with any type of paresis can be a scary and intimidating experience. Because of this, it is crucial to develop a solid support network. This process starts with a group of skilled physicians, therapists, and other medical professionals that you trust to skillfully address your condition.

In addition, many hospitals or community centers have support groups that have been established to connect individuals who are coping with the many paresis-causing diagnoses. Online communities are also prevalent and make it easier to share your experiences with others who are going through similar journeys. Finding a support network can remind you that you are not alone and keep you from losing hope! 

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Article Sources
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  1. Cleveland Clinic. Paralysis. Updated April 21, 2017. 

  2. Christopher and Dana Reeve Foundation. Stroke (cerebral vascular accident (CVA) and spinal stroke).

  3. Cleveland Clinic. Cerebral palsy. Updated December 11, 2020. 

  4. Weill Cornell Medicine. Vocal fold paresis. Updated 2020. 

  5. Saguil A. Evaluation of the patient with muscle weakness. Amercian Family Physician. 2005;71(7):1327-1336.

  6. Stanford Healthcare. Symptoms of spinal cord injury. Updated 2020. 

  7. Cleveland clinic. Multiple sclerosis. Updated February 10, 2021. 

  8. Johns Hopkins Medicine. Bell’s palsy.