If you have epilepsy, it means that you have had repeated seizures. 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.
The brain contains millions of nerve cells (neurons). Normally, the nerve cells are constantly sending tiny electrical messages down nerves to all parts of the body. Different parts of the brain control different parts and functions of the body. Therefore, the symptoms that occur during a seizure depend on where the abnormal burst of electrical activity occurs. Symptoms that may occur during a seizure can affect your muscles, sensations, behaviour, emotions, consciousness, or a combination of these. The different types of seizures are discussed below.
If a person has a single seizure, it does not necessarily mean that he/she has epilepsy. The definition of epilepsy is more than one seizure. The frequency of seizures in people with epilepsy varies. In some cases there may be years between seizures. At the other extreme, in some cases the seizures occur every day. For others, the frequency of seizures is somewhere in between these extremes.
Epilepsy can affect anyone at any age.
Epileptic seizures arise from within the brain. A seizure can also be caused by external factors which may affect the brain. For example, a high fever may cause a febrile convulsion. Other causes of seizures include: lack of oxygen, a low blood sugar level, certain drugs, poisons, and a lot of alcohol. Seizures caused by these external factors are not classed as epilepsy.
Different types of epilepsy and seizures
Seizures are divided into two main types – generalised and partial. If one has epilepsy it is usual to have recurrences of the same type of seizure. However, some people have different types of seizure at different times.
These occur if the abnormal electrical activity affects all or most of the brain. The symptoms tend to be general and involve much of the body.
There are various types of generalised seizure:
- A tonic-clonic seizure is the most common type of generalised seizure. With this type of seizure the whole body stiffens, consciousness is lost, and then the whole body shakes (convulses) due to uncontrollable muscle contractions.
- Absence seizure is another type of generalised seizure. With this type of seizure there is a brief loss of consciousness or awareness. There is no convulsion, the patient does not fall over, and it usually lasts only seconds. Absence seizures mainly occur in children.
- A myoclonic seizure is caused by a sudden contraction of the muscles, which causes a jerk. These can affect the whole body but often occur in just one or both arms.
- A tonic seizure causes a brief loss of consciousness, and the patient may become stiff and fall to the ground.
- An atonic seizure causes the patient to become limp and to collapse, often with only a brief loss of consciousness.
Partial seizures are also called focal seizures. In these types of seizures the burst of electrical activity starts in, and stays in, one part of the brain.
- Simple partial seizures: There are muscular jerks or strange sensations in one arm or leg. A patient may develop an odd taste, or pins and needles in one part of the body. There is no loss of consciousness or awareness.
- Complex partial seizures. Depending on the part of the brain affected, the patient may behave strangely for a few seconds or minutes. For example, he may fiddle with an object, or mumble, or wander aimlessly. In addition, he may also feel odd emotions, fears, feelings, visions, or sensations. These differ from simple partial seizures in that consciousness is affected. The patient may not remember having a seizure.
What causes epilepsy?
Unknown cause (idiopathic epilepsy)
In many cases, no cause for the seizures can be found. The abnormal bursts of electrical activity in the brain occur for no known reason. Genetic (hereditary) factors may play a part in some cases. People with idiopathic epilepsy usually have no other neurological (brain) condition. Medication to control seizures usually works very well.
In some cases, an underlying brain condition or brain damage causes epilepsy. Some conditions are present at birth. Some conditions develop later in life. There are many such conditions. For example: a patch of scar tissue in a part of the brain, a head injury, stroke, cerebral palsy, some genetic syndromes, growths or tumours of the brain, and previous infections of the brain such as meningitis, encephalitis. The condition may irritate the surrounding brain cells and trigger seizures.
What triggers a seizure?
There is often no apparent reason why a seizure occurs at one time and not at another. However, some people with epilepsy find that certain triggers make a seizure more likely. These are not the cause of epilepsy, but may trigger a seizure on some occasions.
Possible triggers may include:
- Stress or anxiety.
- Some medicines such as antidepressants, antipsychotic medication (these lower the seizure threshold in the brain).
- Lack of sleep, or tiredness.
- Irregular meals (or skipping meals) which may cause a low blood sugar level.
- Heavy alcohol intake or using street drugs.
- Flickering lights such as from strobe lighting or video games.
- Menstruation (periods).
- Illnesses which cause fever such as flu or other infections.
How is epilepsy diagnosed?
A doctor should be consulted if one has had a possible seizure. The most important part of confirming the diagnosis is the description of what happened. Other conditions can look like seizures – for example, faints, panic attacks, collapses due to heart problems, breath-holding attacks in children.
Therefore, it is important that a doctor should have a clear description of what happened during the event. It may be that a person who witnessed the seizure may be able to give a more accurate description of what happened during the seizure.
There is no one test to confirm a diagnosis of epilepsy. However, tests such as brain scans, electroencephalogram (EEG – brainwave recordings) and blood tests may help to make a diagnosis.
- A brain scan – usually a magnetic resonance imaging (MRI) or computed tomography (CT) scan – shows the structure of different parts of the brain. This may be performed in some people.
- EEG. This test records the electrical activity of the brain. Special stickers are placed on various parts of the scalp. They are connected to the EEG machine. This amplifies the tiny electrical messages given off by the brain and records their pattern on paper or computer. The test is painless. Some types of seizure produce typical EEG patterns. However, a normal recording does not rule out epilepsy, and not all EEG abnormalities are related to epilepsy.
- Blood tests and other tests may be advised to check on one’s general well-being. They may also look for other possible causes of the event.
Although helpful, tests are not foolproof. It is possible to have epilepsy with normal test results. Also, if an abnormality is found on a brain scan, it does not prove that it causes seizures.
However, tests may help to decide if the event was a seizure, or caused by something else. It is unusual for a diagnosis of epilepsy to be made after one seizure, as the definition of epilepsy is recurrent seizures. For this reason a doctor may suggest to wait and see if it happens again before making a firm diagnosis of epilepsy.
What are the treatments for epilepsy?
Epilepsy cannot be cured with medication. However, with the right type and strength of medication, the majority of people with epilepsy do not have seizures. The medicines work by stabilising the electrical activity of the brain. The medication needs to be taken every day to prevent seizures. Deciding on which medicine to prescribe depends on the type of epilepsy, age, other medicines for other conditions, possible side-effects, whether a patient is pregnant or if planning a pregnancy.
One medicine can prevent seizures in most cases. A low dose is usually started at first. The dose may be increased if this fails to prevent seizures. In some cases two medicines are needed to prevent seizures.
Medication is commonly started after a second seizure that occurs within 12 months of the first. However, there are no definite rules and the decision to start medication should be made after a full discussion with the doctor.
Other treatments for epilepsy
- Surgery to remove a small part of the brain which is the underlying cause of the epilepsy. This is only a suitable option if your seizures start in one small area of your brain (this means it is only possible for a minority of people with epilepsy). It may be considered when medication fails to prevent seizures. However, there are risks from operations.
- Vagal nerve stimulation is a treatment for epilepsy, where a small generator is implanted under the skin below the left collar bone. The vagus nerve is stimulated to reduce the frequency and intensity of seizure.
- The ketogenic diet is a diet very high in fat, low in protein and almost carbohydrate-free which can be effective in the treatment of difficult-to-control seizures in children.
What is the outlook (prognosis) for people with epilepsy?
The success in preventing seizures by medication varies depending on the type of epilepsy. If no underlying cause can be found for the seizures (idiopathic epilepsy),there is a good chance that medication can fully control the seizures. Seizures caused by some underlying brain problems may be more difficult to control.
The overall outlook is better than many people realise. With medication, about 8 in 10 people with epilepsy are well controlled with either no, or few, seizures. The remaining 2 in 10 people experience seizures, despite medication. A very small number of people with epilepsy have sudden unexplained death. The exact cause of this is unknown, but may be related to a change in the breathing pattern or to abnormal heart rhythms during a seizure. However, this is rare and the vast majority of people with epilepsy fully recover following each seizure.
Most people with epilepsy live full and active lives, but may have to accept some changes to their lifestyle.