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Hemiplegia is a neurological condition. It affects everyone differently but its most obvious result is a varying degree of weakness and lack of control in one side of the body. You may be reading this because your child or someone you know has hemiplegia. They may also have epilepsy, or you may have heard that epilepsy is common in people with hemiplegia. Here we look at hemiplegia and epilepsy, and why these conditions sometimes happen together.

Both hemiplegia and epilepsy are neurological conditions, which means they are conditions that are caused by something that goes wrong in the brain. Both are relatively common and epilepsy is common in people with hemiplegia. So why do the conditions sometimes happen together? To answer this, it is useful to know a bit about the brain and how it works.

The brain

Our brains are very complex. They control everything we do - our movement, consciousness, thoughts and emotions. The brain is made up of two halves, the left and right hemispheres. The right hemisphere controls the left side of our body, the left hemisphere controls the right side of our body.

When something goes wrong in our brain, for example if our brain does not develop properly before we are born or if we have an accident or head injury, this can affect the way our brain works. Sometimes this effect is permanent, sometimes it can affect us just some of the time.

What is hemiplegia?

Hemiplegia (sometimes called hemiparesis) literally means paralysis of half of the body.

When someone has hemiplegia ('hemi' means 'half' in Greek) it is because one of the hemispheres of their brain is damaged. We talk about a left or right hemiplegia, depending on the side affected.

About one in every 1,000 children has hemiplegia. In the majority of cases the damage to the brain happens before, during or soon after birth, when it is known as congenital hemiplegia.

Some children, however, develop hemiplegia after a stroke (when a bleed or a blood clot damages part of the brain), an accident, a brain infection or tumour. This is called acquired hemiplegia. Some people develop hemiplegia in adulthood, following illnesses such as a stroke, accident, infection or tumour.

Hemiplegia affects everyone differently but it's most obvious result is a varying degree of weakness and lack of control in one side of the body (rather like someone who has had a stroke). Some children are only mildly affected, others more seriously. In some, the leg is more badly affected than the arm, in others it is the arm which is more seriously affected. But in a majority of children, the damage to their brain affects more than their limbs and movement.

Specific learning difficulties such as dyslexia, perceptual and concentration problems are common, as are emotional and behavioural problems. And hemiplegia can also cause medical problems such as visual impairment, speech difficulties and epilepsy.

Hemiplegia is a permanent condition, so it will not go away and it cannot be cured. But it is also non-progressive, which means it will not get any worse, and with help, its effects may be reduced. When a child is diagnosed with hemiplegia, they are usually referred to a child development centre, often within a local hospital. Here, different therapists work with the child to lessen the effects of the condition, strengthen the weakened side of the body and develop the skills of the individual.

What is the relationship between hemiplegia and epilepsy?

Both hemiplegia and epilepsy are conditions caused by a malformation or damage to the brain or a change in the way the brain works. In some people the brain damage that causes hemiplegia can also cause epilepsy. Statistics vary, but at least 20% (one in five) of children with hemiplegia also have epilepsy. In most children with both conditions, epilepsy starts before the age of five and the chances of developing epilepsy seem to reduce as the child gets older, especially after the age of 10.

Seizures and hemiplegia

Hemiplegia is caused by damage or malformation in one half of the brain. If the damage that has caused hemiplegia also causes the epilepsy, it is likely that the child will have focal seizures. However, some children have generalised seizures and some have 'startle' seizures (which happen in response to a shock or surprise, for example a sudden loud noise or by tripping or stumbling when walking). What happens during this type of seizure varies but often it will include stiffening or posturing (making strange movements) of the arm or leg.

Some individuals have more difficult or complicated epilepsy, called epileptic encephalopathies. These are more severe types of epilepsy, with more serious effects. Epileptic encephalopathies can cause learning disabilities and can affect how well someone can think, understand and interact with the world around them.

How is epilepsy treated?

Most children with epilepsy, including those who also have hemiplegia, have their seizures treated with anti-epileptic drugs (AEDs).

When a child's epilepsy doesn't respond to AEDs and they continue to have seizures, brain surgery may be considered. In most cases intelligence and skills will not be seriously affected and the surgery can improve their life dramatically.

The impact of hemiplegia and epilepsy

Both hemiplegia and epilepsy are variable conditions that can affect people in different ways and to different degrees. Many of the effects of these conditions are physical, such as muscle or limb weakness, or seizures. However, there are often emotional effects of living with these conditions. Your child may have many different feelings about living with their condition. And as a parent of someone with hemiplegia and epilepsy you may experience many different emotions at different times too.

If you would like to talk to someone about how you or your child are coping with living with hemiplegia or epilepsy, or you have any questions about either condition, call our helpline.

This information has been written and produced jointly by Hemihelp and the Epilepsy Society, thanks to a grant from the Roald Dahl Foundation.

Information produced: February 2010