What to know about hemiparesis

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Hemiparesis means one-sided weakness. Around 65% of people who have had a stroke experience hemiparesis.

It can happen on one side, unilateral hemiparesis, or on both sides, diplegic or paraplegic hemiparesis, of the body. The part, or parts, of the body affected by hemiparesis depends on the part of the brain affected by the stroke.

The left side of the brain controls language and speech. Injuring the left side of the brain can cause weakness on the right side of the body.

The right side of the brain controls nonverbal communication and some behaviors. Injuring the right side of the brain can cause weakness on the left side of the body.

Some forms of hemiparesis include:

Ipsilateral hemiparesis

Some people experience weakness on the same side of the body as the side of the brain that was affected by the stroke. This is known as ipsilateral hemiparesis.

A 2017 study, involving 8,360 people, concluded that most people with ipsilateral hemiparesis had previously had a stroke on the other side of the brain to their recent stroke. This caused mobility difficulties on the opposite side of the body to the brain injury caused by the earlier stroke.

Ataxic hemiparesis

Ataxia occurs when a person has trouble coordinating their voluntary muscle movements. In ataxic hemiparesis, this difficulty presents on one side of the body.

Ataxia has a number of possible causes, and it can develop gradually or suddenly. When a stroke causes ataxic hemiparesis, for instance, it tends to strike suddenly and progress quickly, with potentially serious consequences.

Spastic hemiparesis

Spasticity refers to the condition where a person has atypical levels of muscle stiffness or tone. For example, approximately 80% of people with cerebral palsy may experience spasticity.

Spastic hemiparesis means having an abnormal level of muscle stiffness on one side of the body. It usually affects a person’s arm more than their leg.

Hemiparesis is different than hemiplegia. Following a stroke, a person can develop either condition.

While hemiparesis causes muscle weakness, hemiplegia causes total loss of muscle function. Loss of muscle function is also called paralysis.

Learn more about paralysis here.

Stroke commonly causes hemiparesis. During a stroke, some parts of the brain do not receive enough oxygen, which can lead to the death of brain cells. If oxygen does not reach the part of the brain that controls movement and strength, it causes hemiparesis.

However, people with other conditions can experience hemiparesis. These may include:

• brain injury
• brain tumor
• cerebral palsy
• multiple sclerosis

Learn more about stroke here.

The one-sided weakness a person with hemiparesis experiences may affect their arms, hands, face, chest, legs, or feet.

This can have one or more of the following effects on a person:

• loss of balance
• difficulty walking
• difficulty grasping objects
• decreased movement precision
• muscle fatigue
• lack of coordination

Hemiparesis is commonly a symptom of stroke. Doctors take computed tomography (CT) images of the brain and its associated blood vessels to diagnose a person. Specifically, CT angiography involves injecting a special dye into the brain and taking a CT scan of its blood vessels and tissues.

A doctor may also use an MRI scan when stroke is suspected to detect any restricted blood flow to the brain. According to older research from 2007, MRIs are considered more accurate at detecting stroke than CT.

Additionally, older research from 2016 found that testing a person’s muscle strength in their hands and feet may be a reliable way to assess a person with long-term hemiparesis following a stroke.

A range of rehabilitation therapies are available for the treatment of hemiparesis:

Modified constraint-induced therapy (mCIT)

This is an effective treatment to enhance upper limb function in people following a stroke. Upper limb dysfunction can have a profound effect on day-to-day activities.

This therapy type focuses on helping limit use of the upper limbs on the unaffected side of the body, thus promoting the use of the more affected limbs. The unaffected upper limbs may need restraining, such as using slings or mitts. It typically involves repeated, concentrated training.

Other therapies, such as mental imagery, may be used to enhance mCIT.

However, further research into the longer-term effects of mCIT is needed.

Mental imagery

Both mental visualization and physical movement activate similar overlapping areas of the brain. This can mean that if a person imagines moving the weakened part of their body, it may activate muscles and the areas of the brain that they would use if they were actually doing the movement.

Combining mental imagery with other therapies can be beneficial in improving impairment and upper extremity activity in people with hemiparesis.

Electrical stimulation

Electrical stimulation involves placing small electrical pads on a person’s weakened muscles. This treatment delivers an electrical shock to the muscle, which encourages contraction.

The shock may either feel like a burning sensation or a mild tingling, depending on the shock intensity.

Improved movement and motor control are benefits of this treatment.

Cortical stimulation

Doctors place a tiny electrode on the dura, which is the membrane covering the brain, of a person receiving cortical stimulation. While the person participates in rehabilitation exercises, the electrode sends an electrical current to the brain.

However, older research from 2016 — specifically the Everest phase III trial — looking into the effectiveness of cortical stimulation in helping a person regain hand motor skills has not been conclusive.

The researchers found that 24 weeks after rehabilitation, the participants who underwent cortical stimulation showed functional improvements when compared with the control group.

Still, they urged caution in interpreting the results because the improvements may have been in part due to the cortical stimulation group receiving more attention from the researchers — a scientific phenomenon known as the “Hawthorne effect.”

Assistive devices

The American Stroke Association (ASA) suggests speaking with a physical therapist, who can recommend an appropriate device to help improve strength and movement in a person with hemiparesis. Devices include:

• braces, such as an ankle-foot brace
• canes
• walkers, or a walking aid with four points of contact with the ground
• wheelchairs

Practicing regularly with an assistive device can help a person improve managing their movements and flexibility, and support repairing damaged nerves. A person should work with a healthcare professional to develop a plan that includes appropriate exercises.

The ASA also suggests a range of home and lifestyle modifications a person with hemiparesis can make to help with improving their motor skills.

Home modifications to help make life easier include:

• raising the toilet seat
• installing a bench in the bathtub, with adhesive strips on the bottom of the tub
• purchasing an electric toothbrush and razor if required
• installing grab bars and ramps wherever helpful in the home

Lifestyle changes to help speed up recovery and prevent falls include:

• staying active to strengthen muscles and improve balance
• wearing flat, wide-toed shoes to help with balance
• using one of the prescribed assistive devices mentioned above rather than grabbing onto furniture for support
• avoiding activities that become unsafe when taking medicines that cause drowsiness
• being mindful while walking to avoid falling

Hemiparesis means one-sided weakness. Symptoms include loss of balance and lack of coordination. A stroke or another type of brain trauma can cause hemiparesis.

Treatments range from electrical stimulation to using assistive devices. A range of lifestyle and home modifications can also support a person’s recovery.