Grand mal (tonic-clonic) seizure: what happens, first aid and treatment

Epilepsy Action explains that tonic-clonic seizures used to be called grand mal seizures, and are sometimes called convulsive seizures. They can have a generalised onset, meaning they appear to involve both sides of the brain from the start. Sometimes a focal seizure, which begins in one area of the brain, spreads to both sides: this is a focal to bilateral tonic-clonic seizure. Sometimes it is not known where the seizure started.

The NHS lists tonic-clonic seizures as one of the main types of epileptic seizure, where you become unconscious and may fall, your muscles get stiff and your body jerks and shakes. Having a seizure does not always mean you have epilepsy, since seizures can have other causes.

Epilepsy Action describes two phases.

• Tonic phase: you lose consciousness, so you will not be aware of what is happening; all your muscles go stiff and, if standing, you fall to the floor; air might push past your voice box, which can sound like crying out; you may bite your tongue or the inside of your mouth.

• Clonic phase: your limbs jerk quickly and rhythmically; you may lose control of your bladder or bowels; your breathing may be affected, causing a blue tinge around the mouth (the skin may turn grey on black or brown skin; discolouration may be easier to see on the lips, gums, inside the eyelids, palms or soles).

• Some people get an aura beforehand, which is actually a focal seizure and can act as a warning, for example a feeling of déjà vu or jerking in one part of the body.

Epilepsy Action says most tonic-clonic seizures last between 1 and 3 minutes, and the jerking usually starts to slow within a minute. Focal to bilateral seizures may last slightly longer. Seizures lasting over 5 minutes, or longer than normal for that person, are a medical emergency called status epilepticus.

The time afterwards is called the post-ictal phase. Epilepsy Action says it can last minutes, hours or even days. You may have a headache and feel sore, tired and unwell; feel confused or have memory problems; go into a deep sleep; and breathing may sound heavy, with a snoring sound. Some people have temporary weakness on one side or cannot move part of their body (Todd's paralysis), which can last from a few minutes up to 36 hours and goes away by itself. A brain scan is usually done if it happens for the first time, to rule out a stroke.

Epilepsy Action gives these steps for helping someone having a tonic-clonic seizure.

• Protect them from injury by removing harmful objects from nearby.

• Cushion their head.

• Look for an epilepsy identity card or jewellery, which may say what to do.

• Time how long the seizure lasts.

• Once the jerking has stopped, help their breathing by gently placing them in the recovery position.

• Stay with them until they are fully recovered, and be calm and reassuring.

• Do not hold them down or put anything in their mouth. Do not move them unless they are in danger. Do not try to bring them round. Do not give them anything to eat or drink until they have fully recovered.

• They may wet themselves; putting a light blanket or piece of clothing over their lower body can help preserve dignity, and moving bystanders away may help.

The NHS says to call 999 if you think someone is having a seizure and any of these apply. Epilepsy Action gives a near-identical list and adds seriously injured or trouble breathing after the seizure.

• It is the first time it has happened.

• It lasts longer than is usual for them, or longer than 5 minutes if you do not know how long their seizures usually last.

• They do not recover as usual afterwards, or they have another seizure without recovering in between.

• They have had 3 or more seizures in 24 hours.

• They are seriously injured during the seizure or have trouble breathing after it has stopped (Epilepsy Action).

A tonic-clonic seizure is a symptom, not a disease. The NHS says epilepsy happens when the normal electrical activity in the brain changes. It is thought to be often related to genes inherited from parents, or to changes in genes, and is sometimes caused by damage to the brain such as after a head injury, stroke or infection. For many people, the cause is not clear.

The NHS says people with epilepsy can keep a diary to identify triggers, such as tiredness, stress, their period, flashing lights, food or drink, and that too much alcohol can increase the risk of seizures. Seizures can also have other causes, which is why a specialist looks for the cause after a first seizure.

The NHS says that if you or your child have had a seizure you will need to see a specialist doctor, who will check what caused it and whether you might have epilepsy. They will ask about what happened before, during and after, and if someone else saw it, it can help to bring them to the appointment. Tests may include an EEG (brain electrical activity), an ECG (heart tracing), scans such as MRI or CT, blood tests and genetic testing.

You will usually be diagnosed with epilepsy if you have had more than one seizure, or if tests show you are at risk of having more seizures. If you think you or your child may have had a seizure for the first time and did not go to hospital, the NHS says to ask for an urgent GP appointment or get help from NHS 111.

The NHS says the main treatment for epilepsy is medicine to prevent seizures, called anti-seizure medicine. The medicine recommended depends on the type of seizures and things like age, sex and other conditions, and you may need to try different medicines. You may also be given emergency medicine for a seizure that lasts longer than usual, which a family member or carer would give. For most people medicines work well; rarely, other treatments such as brain surgery, a vagus nerve stimulator or a ketogenic diet are used.

Do not miss doses or change or stop your medicine without advice from your GP or specialist. If you have not had a seizure for 2 years, your specialist may suggest trying to stop treatment by gradually reducing the dose. Some epilepsy medicines can harm a baby if taken in pregnancy, so discuss treatment with a specialist if there is a chance you could become pregnant.

The NHS and Epilepsy Action suggest making your family and friends aware of what to do, carrying medical ID, keeping a seizure diary, making your home safer (carpets, radiator covers), considering an alarm, having showers rather than baths and thinking about safety when cooking or swimming. If you have had any type of seizure you must not drive, and you must tell the DVLA; when you can drive again depends on the type of seizure and when it last happened.

Epilepsy Action says SUDEP (sudden unexpected death in epilepsy) is rare, affecting around 1 in every 1,000 people with epilepsy each year, and that uncontrolled tonic-clonic seizures increase the risk. The NHS says treatment can reduce the risk. Talk to your healthcare professional about the risks.

People often use "grand mal" and "petit mal" loosely. The NHS describes the main types of epileptic seizure.

On the NHS, a first seizure is assessed by a specialist, and if epilepsy is diagnosed you are supported by your GP and a specialist team with check-ups at least once a year and a care plan that tells your family or carers what to do during a seizure.

Private neurology appointments and EEG or MRI tests are available, usually for faster access. Ask that results are shared with your GP, and remember the driving rules apply whichever route you use.