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Not everyone with epilepsy has the same type of fit. There are two main groups and a number of different types within each group. The two main groups are generalised seizures and partial seizures. When the first abnormal electrical discharge arises from both sides of the brain this is known as a generalised seizure. When the first abnormal electrical discharge arises from one specific part of the cerebral hemisphere this is known as a partial seizure.

Generalised seizures
During generalised seizures, the abnormal electrical discharge arises from both sides of the brain at the same time and the signs are seen on both sides of the body. There are six types of generalised seizure.

1. Absences
These are fits that mainly affect children, where for between five and 20 seconds a child briefly loses awareness of his or her surroundings. Absences can happen several times a day and affect a child’s performance at school. There may also be eye fluttering or lip-smacking movements during the absence attack.

2. Myoclonic jerks
These are short, shock-like contractions of different muscle groups anywhere in the body but usually in the arms and legs. The jerks last for a fraction of a second and the person can fling a limb and throw an object held in the hand involuntarily.

3. Atonic or astatic seizures
These cause an immediate relaxation of muscles so that the person may suddenly fall to the ground, sometimes injuring themselves as they fall.

4. Tonic seizures
These seizures last between five and ten seconds and lead to a sudden contraction of whole body muscles, which causes the person to fall, and sometimes to injure themselves as they fall.

5. Clonic seizures
During these seizures there are sudden, rhythmic contractions of groups of muscles causing jerking and twitches of various muscle groups which may last up to two minutes.

6. Tonic clonic seizures
These seizures have two stages: they start with a tonic phase with stiffness followed by a clonic phase with rhythmic contractions. The whole seizure may last between one and three minutes. If these seizures recur without the person regaining consciousness then the condition is very serious and is termed status
epilepticus.

Partial seizures
In partial seizures, the abnormal electrical discharge starts in one part of the brain and may spread to another part of the brain. This spread is known as secondary generalisation. The person sometimes feels the symptoms of the abnormal electrical discharge in the part of the body controlled by the specific brain area that is being affected. If the person remains conscious during the fit then it is known as a simple partial seizure, but if the level of consciousness is affected then the term complex partial seizure is used.

People who have simple partial seizures often describe changes in sensory perception such as a strange taste or smell, sudden fearfulness or a feeling of
familiarity with events, which had never previously been encountered (“deja vu”). These unexpected thoughts are a result of abnormal electrical discharge starting in the temporal lobe of the brain, which is the area of the brain responsible for processing various thoughts and emotions. If the electrical discharge starts in another area, the person may complain of tingling or numbness in one of their limbs or face depending on the neurones affected and the progression of the abnormal electrical spread.

Complex partial seizures
The seizures can either start as simple and progress or start as complex from the outset, with confusion and sometimes strange behaviour such as lip smacking, with no memory of the event. Simple and complex partial seizures can progress to generalised tonic clonic seizures (secondary generalisation).

There are some other older terms, which are still in common use. Grand mal means a generalised tonic clonic seizure wheather the onset is partial or generalised. Petit mal is another name for absences of the generalised type. Temporal lobe seizures mean simple or partial seizures arising from the temporal lobe of the brain.

The term aura is used to describe the warning that a seizure is about to happen. The aura is in fact the start of the abnormal electrical activity in the brain before a seizure spreads to other neighbouring areas of the brain.

Seizures do not seem to injure the brain unless they quickly recur without the person regaining consciousness and they last more than 30 minutes. Many people have dozens of seizures in their lives without intellectual or physical injury. Extremely rarely, a seizure can cause suffocation and death. This occurs in about one in 400-600 people with active epilepsy and is known as sudden unexpected death in epilepsy syndrome. People with well-controlled epilepsy are less at risk than those experiencing daily, generalised seizures. This is a particularly important reason for people with epilepsy to take their drugs regularly. Failing to take the drugs regularly also increases the risk of accidents such as falls, drowning and non-stop seizures, a condition known as status epilepticus. This condition is a medical emergency that requires urgent hospital admission and intensive care.

Epilepsy syndromes
A syndrome is a group of symptoms and signs that occur together in a way that is non-coincidental. Epilepsy syndromes tend to start at a specific age and proceed in a reasonably set pattern. It is therefore possible in many cases to predict their outcome and their response to medication. The syndromes can be benign, in which case they do not have harmful consequences. The best example of this is Benign Rolandic epilepsy of childhood. In this condition the seizures occur during sleep in older children. The electric discharge is from a specific area on the surface of the brain, known as the Rolandic fissure and the child will grow out of the seizures without the need for treatment in most cases.

Juvenile onset myoclonic epilepsy also starts in young people and causes specific types of seizure and EEG abnormalities. The seizures occur on awakening and are associated with body jerking and sensitivity to flickering light. This condition is usually straightforward to control, but requires life-long treatment.

A rare type of epilepsy is Lennox-Gastaut syndrome, which starts in childhood and may have an effect on intellectual development and may be hard to control. Children with Lennox-Gastaut syndrome may need special schooling or sometimes residential care. There are many causes for Lennox-Gastaut syndrome including meningitis and brain damage before or during the time of birth, or in the early stages of development.

Some young babies will start by having another rare and severe epilepsy syndrome called West syndrome in the first year of life and then go on to develop Lennox-Gastaut syndrome in the second or third year of life.