About 1 in 30 people in the UK develop epilepsy at some stage. It most commonly starts in childhood and in people aged over 60. However, epilepsy can begin at any age. Seizures are well controlled by treatment in about 4 in 5 cases. There are different types of epilepsy. This leaflet is about epilepsy with focal seizures (used to be called partial seizures).
What is a seizure and what is epilepsy?
A seizure is a short episode of symptoms caused by a burst of abnormal electrical activity in the brain. Typically, a seizure lasts from a few seconds to a few minutes. (Older words for seizures include convulsions and fits.)
If you have epilepsy, it means that you have had repeated seizures. If you have a single seizure, it does not necessarily mean that you have epilepsy. About 1 person in 20 has a seizure at some time in their life. It may be the only one that occurs. The definition of epilepsy is more than one seizure. The frequency of seizures in people with epilepsy varies.
There are different types of seizures but they are broadly divided into two main types - generalised and focal. Many people associate epilepsy with generalised convulsive seizures. However, some people develop focal seizures.
What is a focal seizure?
With a focal seizure, the burst of electrical activity stays in one part of the brain. Therefore, you tend to have localised (focal) symptoms. Different parts of the brain control different functions and so symptoms depend on which part of the brain is affected.
Focal aware seizures (simple focal seizures)
In this type of 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 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.
What are the symptoms of focal aware seizures?
The symptoms will depend on which part of the brain is affected by the 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, or 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, or an 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 (eg, coloured or flashing lights) or seeing something that isn't actually there (hallucinations).
How can I help someone having a focal seizure?
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.
Further reading and references
Epilepsies: diagnosis and management; NICE Clinical Guideline (January 2012)
Diagnosis and management of epilepsy in adults; Scottish Intercollegiate Guidelines Network - SIGN (2015)
Epilepsy; NICE CKS, March 2018 (UK access only)
de Tisi J, Bell GS, Peacock JL, et al; The long-term outcome of adult epilepsy surgery, patterns of seizure remission, and relapse: a cohort study. Lancet. 2011 Oct 15378(9800):1388-95.