Focal seizures

What is a focal seizure?

A seizure is a problem caused by a sudden burst of electrical activity in the brain. With a focal seizure, the burst of electrical activity stays in one part of the brain. Therefore, you tend to have localised (focal) seizure symptoms. Different parts of the brain control different functions and so symptoms depend on which part of the brain is affected.

Seizures can be caused by lots of different things, including epilepsy. See the epilepsy leaflet for more. In general, though, focal seizures tend to only occur in people with epilepsy.

Focal seizures tend to cause changes in awareness, behaviour, or sensation.

Focal seizures can be:

• Focal aware seizures, or simple partial seizures, where you are awake and aware of what is happening during the seizure.

• Focal impaired awareness seizures, or complex partial seizures, where you are confused or are unaware of what is happening during the seizure.

The symptoms will depend on which part of the brain is affected by the focal seizure.

• The temporal lobes of the brain help to deal with mood and behaviour.

  • Therefore, you may have strange feelings, sensations and emotions during a complex focal seizure.

  • It may feel like being in a dream.

  • Your surroundings may appear strange or oddly familiar.

  • It may be difficult to explain the feelings or sensations that occur.

  • To an onlooker, you may appear to be in a trance or behave strangely for a few seconds or minutes. For example, you may wander with no apparent purpose.

  • Some people smack their lips, fumble at clothes, appear to fidget, swallow repeatedly, or do other repetitive movements.

• Focal aware seizures that start in the frontal lobe of your brain may cause symptoms that include:

  • A strange feeling (like a wave) going through the head.

  • Stiffness or twitching of a part of your body.

• Focal aware seizures that start in the parietal lobe of your brain may cause:

  • Numbness or tingling.

  • Odd sensation that an arm or leg feels bigger or smaller than it actually is.

• Focal aware seizures starting in the occipital lobe may include:

  • Visual disturbances (for example, coloured or flashing lights).

  • Seeing something that isn't actually there (hallucinations).

Focal aware seizures (simple focal seizures)

In this type of focal seizure you may have muscular jerks or strange sensations in one arm or leg. You may feel, hear, see, smell, or taste odd sensations. Some people develop pins and needles in one part of the body. However, you do not lose consciousness or awareness. A simple focal seizure usually lasts just a few seconds or minutes. For each individual, the same movement or sensation tends to recur each time a seizure occurs.

Focal impaired awareness seizures (complex focal seizures)

During this type of focal seizure, you are not aware of your surroundings or of what you are doing. In effect, you have a partial loss of consciousness (which differs from a simple focal seizure). This type of focal seizure can arise from any part of the brain but most commonly arises from a part of the brain called a temporal lobe. Therefore, this type is sometimes called a temporal lobe seizure.

Sometimes a focal seizure develops into a generalised convulsive seizure. This is called a secondary generalised seizure.

A convulsive seizure is when someone loses consciousness, their muscles stiffen, and then they have rhythmic shaking of their arms and legs.

There are many different treatments for epilepsy and also medicines to help prevent people with epilepsy having seizures. Lamotrigine or levetiracetam is recommended as first-choice treatment for focal seizures. For information about treatments and prevention, see the separate leaflet called Epilepsy medication and side-effects.

As focal seizures can take many different forms, bystanders need to take a common sense approach. Nearly all focal seizures stop within a few minutes by themselves.

• Gentle and quiet reassurance may be all that is needed until the seizure ends. If the affected person appears confused or is wandering, try to guide them away from any danger.

• Sometimes a focal seizure develops into a convulsive one, so be aware of this.

  • It may be best to guide the person to sit down in a soft chair or away from any dangerous places.

  • Stay with the person until they have recovered and are fully aware of their surroundings.

For more information, see the separate leaflets called Epilepsy, Types of seizures and Epilepsy medication and side-effects.