Hemiparesis is partial weakness on one side of the body. It can affect either the left or right side of the body. The weakness may involve the arms, hands, legs, face or a combination. About 80% of stroke survivors experience hemiparesis, making it one of the most common effects of a stroke.1

People who have hemiparesis are still able to move the affected side of the body, but with limited strength. One side of the body may become completely weak, and this condition is called hemiplegia.

The most obvious symptom of hemiparesis is the partial paralysis of one side of the body. Symptoms correspond to the side of the brain or spine that has been damaged.

An injury to the left side of the brain typically results in weakness on the right side of the body. An injury to the right side of the brain typically results in weakness on the left side of the body.

Depending on the type of spine injury and the level of injury within the spine, hemiparesis may involve the same side of the body as the spine injury or may involve the opposite side.

Some symptoms of hemiparesis include the following:2

Inability to maintain balance
Difficulty walking
Inability to grasp objects
Decreased precision in movement
Muscle fatigue
Lack of coordination
Leaning to one side while standing, walking or sitting
Loss of bowel or bladder control
In addition to stroke, hemiparesis can be caused by a number of other medical conditions.3 The most common causes of hemiparesis are the following:

Multiple sclerosis
Traumatic injury: May affect the brain, spine or nerves
Congenital medical conditions such as cerebral palsy that are present from birth
Spine disease
A tumor of the brain or spine
Infection of the brain, spine or meninges
Psychological and psychiatric conditions (can cause temporary weakness)
Postictal paralysis: Temporary weakness after a seizure
Inflammatory and autoimmune conditions

If you complain of any symptoms of hemiparesis, your doctor will do a physical examination. It can be difficult to determine whether your symptoms are the result of weakness, pain, or another cause.

The physical examination includes a test of your reflexes, sensation, and strength. Your doctor will rate your strength on a scale of 1-5.4 This rating can also help when the same doctor or other doctors assess your strength at a later time, as it can be used as a comparison.

Muscle Strength Rating Scale
The rating scale for muscle strength is as follows:

0/5: No movement
1/5: Mild muscle twitching
2/5: Movements from side to side, but cannot lift the arm or leg up against gravity
3/5: Can move up against gravity, but not against any force, such as mild pushing by the examiner
4/5: Can move against force, such as pushing by the examiner, but not with normal expected strength
5/5: Can move against force with expected strength
Diagnosis of the cause of hemiparesis can also be confirmed with imaging studies, which may include the following:

Brain or spine computerized tomography (CT) scan
Brain or spine magnetic resonance imaging (MRI)
Treatment of hemiparesis is first directed towards targeted treatment of the cause, whether the cause is a stroke, a brain tumor, or an infection, etc. The goal of long-term treatment of hemiparesis is to strengthen motor skills and coordination and to improve your ability to manage everyday activities.

Physical and occupational therapy are important in the recovery of hemiparesis. Therapy may include the use of electrical stimulation to the brain, imagery, and the use of assistive devices such as a cane, walker or wheelchair.

Modifications to the home may need to be made to accommodate and help increase mobility. Some of the modifications may include:

Grab bars
Raised toilet seats
A bench in the tub
Non-slip adhesive strips in the bathtub
Electric toothbrushes
Electric razors
Fortunately, hemiparesis is not a progressive condition unless there is evidence of an aggressive, growing brain tumor.