Epilepsy with Tonic-clonic Seizures

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At least 1 in 30 people in the UK develop epilepsy at some stage. It most commonly starts in childhood and in people over the age of 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 tonic-clonic 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. (Older words for seizures include convulsions and fits.)

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.

There are different types of seizures but they are broadly divided into two main types - generalised and focal (used to be called partial):

  • Generalised seizures: these occur if you have a burst of abnormal electrical activity which spreads throughout the brain. It affects consciousness and may cause a convulsion.
  • Focal seizures: in focal seizures the burst of electrical activity starts in, and stays in, one part of the brain. Therefore, you tend to have localised (focal) symptoms. Different parts of the brain control different functions, so symptoms depend on which part of the brain is affected. Focal seizures may not affect consciousness but may affect sensations, emotions, behaviours, muscles, or combinations of these.

A tonic-clonic seizure is the most common type of generalised seizure. The following gives a typical description:

Your body becomes rigid due to strong muscular contractions (the tonic part). You lose consciousness and fall. Your chest muscles contract and force air out of your mouth, often with a grunt. Your jaw muscles contract and you may bite your tongue. Saliva may escape from your mouth. Your bladder may contract and you may pass urine. This stiff or tonic phase soon passes into the clonic (shaking or convulsive) phase. This occurs when the muscles repeatedly contract and relax. Your whole body appears to shake. This may last from a few seconds to a few minutes.

When the seizure has stopped, you gradually regain consciousness but you may be confused and dazed for a while. The time taken to recover varies. You may have some soreness due to the muscular contractions. You may have a headache and want to sleep after a seizure.

You may have some warning symptoms for a short while before a seizure. This is called an aura. The aura can take various forms - for example, odd movements, odd sensations, or intense emotions. However, many people do not have auras, and a seizure commonly occurs without any warning.

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. 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.

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 temperature (fever) may cause a febrile convulsion. Other causes of seizures include lack of oxygen, a low blood sugar level, poisons, and a lot of alcohol. Seizures caused by these external factors are not classed as 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 apparent reason. It is unclear why they start or why they continue to occur. Hereditary (genetic) factors may play a part in some cases. People with idiopathic epilepsy usually have no other brain (neurological) condition. Medication to control seizures usually works well.

Symptomatic epilepsy

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.
  • A stroke.
  • Cerebral palsy.
  • Some genetic syndromes.
  • Growths or tumours of the brain.
  • Previous infections of the brain such as meningitis, encephalitis.

The condition may irritate the surrounding brain cells and trigger seizures.

Some underlying conditions may cause no other problems apart from seizures. In other cases, the underlying condition may cause other problems in addition to the seizures.

These days, with more advanced scans and tests, a cause can be found for some cases previously thought to be of unknown cause (idiopathic). For example, a small piece of scar tissue in the brain, or a small anomaly of some blood vessels inside the brain. These may now be found by modern brain scanning equipment which is more sophisticated than in the past.

There is often no apparent reason why a seizure occurs at one time and not 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.
  • Heavy drinking.
  • Street drugs.
  • Some medicines such as antidepressants, antipsychotic medication.
  • Lack of sleep, or tiredness.
  • Irregular meals which cause a low blood sugar level.
  • Flickering lights such as from strobe lighting.
  • Periods (menstruation).
  • Illnesses which cause a high temperature (fever), such as flu or other infections.

It may be worth keeping a seizure diary. This may show a pattern which may identify a possible avoidable trigger. Keeping a healthy lifestyle, a well-balanced diet, regular meals and not getting overtired may help you to feel better and may reduce the chance of seizures occurring.

You should see a doctor if you have had a possible seizure or similar event. Sometimes it is difficult for a doctor to confirm that you have had a 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, and some other problems.

Therefore, it is important that a doctor should have a clear description of what happened during the event. Preferably this is from the person affected and also from an eyewitness. The description may be typical of a seizure. However, sometimes it is difficult for a doctor to confirm the diagnosis definitely. Tests such as brain scans, electroencephalogram (EEG - brainwave recordings) and blood tests may help.

  • A brain scan - usually a magnetic resonance imaging (MRI) scan or computed tomography (CT) scan - can show the structure of different parts of the brain. A brain scan is not always necessary.
  • Electroencephalograph (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 your 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.


Epilepsy cannot be cured with medication. However, various medicines can prevent seizures. They work by stabilising the electrical activity of the brain. You need to take medication every day to prevent seizures. Seizures are well controlled by medication in about 4 out of 5 cases.

Deciding on which medicine to prescribe depends on such things as:

  • Your type of epilepsy.
  • Your age.
  • Other medicines that you may take for other conditions.
  • Possible side-effects.
  • Whether you are pregnant or if you are 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.

The decision when to start medication may be difficult. A first seizure may not mean that you have epilepsy, as a second seizure may never happen or may occur years later. The decision to start medication should be made by weighing up all the pros and cons of starting, or not starting, the medicine. A common option is to wait and see after a first seizure. If you have a second seizure within a few months, more are likely. 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 your doctor.

Some points about medication for epilepsy include the following:

  • Ask your doctor how long treatment is likely to be advised. This will vary from case to case. If you have not had seizures for several years, you may wish to try stopping medication. But this depends on your particular type of epilepsy. There are many different types of epilepsy, some of which are age-dependent but some that will need medication for life. Your life circumstances may influence the decision about stopping medication. For example, if you have recently regained your driving licence, the risk of losing it again for a year if a seizure occurs may affect your decision. However, if you are a teenager who has been free of seizures for some years, you may be happy to take the risk.
  • Although the list of possible side-effects for each medicine seems long, in practice, most people have few or no side-effects, or just minor ones. Ask your doctor which side-effects are important to look out for. If you develop a troublesome side-effect it may be dose-related, or may diminish in time. Alternatively, a switch to another medicine may be advised.
  • Medicines which are used for other conditions may interfere with medication for epilepsy. If you are prescribed or buy another medicine, remind your doctor or pharmacist that you take medication for epilepsy. Even preparations like indigestion medicines may interact with your epilepsy medication which may increase your chance of having a seizure.
  • Some epilepsy treatments interfere with the contraceptive pill. You may need a higher-dose pill or an alternative method of contraception.
  • Tell your doctor if you intend to become pregnant. Pre-conception counselling is important for women with epilepsy.
  • If you have epilepsy and take medication, you are exempt from prescription charges for all your prescriptions. You need an exemption certificate. You can obtain this from your pharmacist.

Are there any other treatments?

  • 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. Only a small number of people with epilepsy are suitable for surgery and, even for those that are, there are no guarantees of success. Also, there are risks from operations. Surgical techniques continue to improve and surgery may become an option for more and more people in the future.
  • Vagal nerve stimulation is a treatment for epilepsy where a small generator is implanted under the skin below the left collarbone. The vagus nerve is stimulated to reduce the frequency and intensity of seizures. This can be suitable for some people with seizures that are difficult to control with medication.
  • The ketogenic diet is a diet very high in fat, low in protein and almost carbohydrate-free. This can be effective in the treatment of difficult-to-control seizures in some children.
  • Complementary therapies such as aromatherapy may help with relaxation and relieve stress but have no proven effect on preventing seizures.
  • Counselling. Some people with epilepsy become anxious or depressed about their condition. A doctor may be able to arrange counselling with the aim of overcoming such feelings. Genetic counselling may be appropriate if the type of epilepsy is thought to have an hereditary pattern.

A seizure cannot be shortened or altered. However, a bystander can help in the following ways:

During a seizure:

  • Note the time.
  • Do - prevent crowds gathering round.
  • Do - place a cushion or some clothing under the head to prevent injury.
  • Do not - try to restrain the person. If there is a warning (aura) before a seizure, it may be possible to guide the person to a safe place or cushion the expected fall to the ground. When the seizure starts, do not try to hold the person upright but let them lie down.
  • Do not - move the person unless they are in a dangerous place (for example, in a road or next to a fire). If possible, move dangerous objects away from the person.
  • Do not - place anything in the person's mouth or try to move their tongue.

Once the seizure has stopped:

  • Do - roll the person on to their side into the recovery position.
  • Do - check that breathing has resumed normally. It is normal for breathing to stop for a short while during the stiff (tonic) part of the seizure. The face will go pale or bluish. During the convulsive (clonic) part, breathing is irregular. After the seizure is over, breathing returns to normal. If not, check there is nothing stopping breathing, such as food or false teeth. The recovery position helps saliva and anything in the mouth - such as food or sick (vomit) - to drain out of the mouth and not back into the throat.
  • Do - stay and talk to the person. Give reassurance until they are fully recovered. It may take a while for the person to wake up fully. Do not leave a person alone whilst they remain dazed or confused.
  • Do not - offer something to eat or drink until you are sure they are fully recovered.

There is usually no need to call a doctor or an ambulance unless:

  • It is their first seizure.
  • Injury has occurred which cannot be dealt with.
  • The seizure does not stop after a few minutes. Status epilepticus is rare but means a seizure does not stop, or they keep recurring one after the other. This is an emergency and needs urgent treatment to stop the seizure.
  • There is difficulty with breathing.

The success in preventing seizures by medication varies depending on the type of epilepsy. For example, if no underlying cause can be found for your seizures (idiopathic epilepsy), you have a good chance that medication can fully control your seizures. Seizures caused by some underlying brain problems may be more difficult to control.

The overall outlook is better than many people realise. The following figures are based on studies of people with epilepsy which looked back over a five-year period. These figures are based on grouping people with all types of epilepsy together, which gives an overall picture:

  • About 5 in 10 people with epilepsy will have no seizures at all over a five-year period. Many of these people will be taking medication to stop seizures. Some will have stopped treatment having had two or more years without a seizure whilst taking medication.
  • About 3 in 10 people with epilepsy will have some seizures in this five-year period but far fewer than if they had not taken medication.
  • So, in total, 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 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.

A trial without medication may be an option if you have not had any seizures over 2-3 years. If a decision to stop treatment is made, a gradual reduction of the dose of medication is usually advised, over several months. Never stop taking medication without discussing it with a doctor.

The above section on outlook (prognosis) relates just to seizures. Some underlying brain conditions which cause seizures may cause additional problems.

Original Author:
Dr Tim Kenny
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
4435 (v41)
Last Checked:
Next Review:
The Information Standard - certified member
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