Hemiplegia is a form of paralysis that affects just one side of the body, often just one arm and one leg, but occasionally with symptoms extending partially into the torso. A related condition, hemiparesis, is significant loss of strength and mobility on one side of the body, but without full paralysis. Some people with hemiplegia develop the condition after a bout of hemiparesis. Others may alternate between times of hemiparesis and hemiplegia.
The brain is divided into two hemispheres, separated by a bundle of fibers called the corpus callosum. Generally speaking, the right side of the brain controls muscles and other functions on the left side of the body, while the left side of the brain controls much of the right side of the body. Thus hemiplegia and hemiparesis almost always indicate a problem with one side of the brain.
Hemiplegia may come on suddenly, or develop slowly over time. A condition related to hemiplegia, spastic hemiplegia, causes the muscles to get stuck in a contraction, resulting in little muscle control, chronic muscle pain, and unpredictable movements. People with hemiplegia often show other signs of brain damage or head injury, and may experience issues with other areas of their bodies.
Hemiplegia, like other forms of paralysis, is characterized by significant loss of sensation and control in the affected area. People with hemiplegia may experience intermittent pain, and may be better able to control their limbs at some times than at others.
Though the arms, legs, and possibly torso are the regions of the body most obviously affected by hemiplegia, in most cases of hemiplegia these body regions are actually perfectly healthy. Instead, the problem resides in the brain, which is unable to produce, send, or interpret signals due to disease or trauma-related damage. Less frequently, hemiplegia results from damage to one side of the spinal cord, but these sorts of injuries more typically produce global problems, not just paralysis on one side of the body.
Some common causes of hemiplegia include:
The course of hemiplegia is highly variable, and heavily dependent on the cause. For many people with hemiplegia, the condition is a temporary one, but others may struggle with hemiplegia for the rest of their life. For some, the paralysis is extensive and complete, producing a total loss of sensation and bodily control. For others, symptoms are less severe. Some of the ways hemiplegia affects the body include:
There's no single treatment approach that works for all people. Instead, treatment is largely dependent on the cause of hemiplegia. Some treatment options include: