What is a seizure?
A seizure (or fit) happens when ordinary brain activity is suddenly upset because electrical activity from one part of the brain has spread uncontrollably to other parts of the brain for a short time. The brain normally produces tiny electrical signals that come from the brain cells and nerves that send messages to each other. Any of the normal brain functions, such as memory, consciousness (that is, awareness of self and the surroundings), movement or sensations, can be temporarily lost or disturbed during the seizure.
What causes seizures?
- Head injury
- Brain tumour
- Infection (meningitis, abscess)
- Drug abuse and overdoses
- Low salt levels in the blood
- Low blood sugar (hypoglycaemia)
- Fever (in children)
- Alcohol withdrawal.
Following extensive testing, a first seizure may later be diagnosed as epilepsy. About half of the people who have a seizure without any identifiable cause will go on to have another seizure. A person is twice as likely to have another seizure after the first one if they have already had a brain injury or previous abnormality. If someone has already had two seizures, there is an 80% chance that more will occur.
The most common causes of prolonged seizures in a person with known epilepsy are failing to take prescribed drugs to stop seizures, change to the dose or medication used to control seizures, or alcohol withdrawal.
What are the different types of seizures?
- Partial seizures or focal seizures involve only part of the brain, and do not usually reduce consciousness or awareness of what is happening. This type of seizure may cause twitching of one limb, or unusual tastes or sensations such as pins and needles in a specific part of the body.
- Complex partial seizures do affect awareness, and the person will have limited or no memory of what happened. These seizures will also be characterised by apparent confusion and automatic movements (such as fiddling with clothes, chewing, or wandering about). The person may respond if spoken to.
- Generalised seizures involve all of the brain and consciousness is lost. They often occur with no warning and the person will have no memory of the event. The most common type is the tonic-clonic convulsive seizure that used to be called the grand mal seizure. In the first part of the seizure the person becomes rigid and may fall down or bite their tongue or cry out. The muscles then relax and tighten rhythmically (the clonic phase). Breathing may become laboured and the person might lose control of their bladder or bowel. After the seizure, the person might feel tired, confused, and have a headache.
- In tonic seizures, there is general stiffening of the muscles without any jerking. The person might fall to the ground and may hurt themselves, but recovery is generally quick.
- Atonic seizures are very uncommon, and involve sudden loss of muscle tone causing the person to fall (drop attacks). The person might be injured by the fall, but recovery is generally rapid.
- Myoclonic seizures involve brief and abrupt jerking of one or more limbs. This can occur by itself, or with generalised seizures, shortly before the person wakes up.
- Absence seizures or petit mal occur most commonly in children. The person experiences a brief interruption of consciousness and becomes unresponsive for several seconds. They may appear blank or staring usually without any other features, except perhaps for a fluttering of the eyelids.
What is the treatment for seizures?
Seizure activity must be stopped promptly, and numerous drugs can be given to do this. Drugs that stop seizures are given through an intravenous cannula, sometimes as a continuous infusion (such as midazolam, clonazepam, or phenytoin). It is important to put the patient in a position to ensure safety and to prevent them from harming themselves. Oxygen may be administered, and in severe cases, the patient may need to be intubated and mechanically ventilated.
What happens in the ICU?
- Monitoring of the heart rate, blood pressure, oxygen saturation and temperature. This will be seen on a bedside monitor.
- Medication and intravenous fluids may be given via a central venous catheter including sedatives (to assist in sleep), analgesics (pain killers) and antibiotics (for infections). These medications will be given via infusion pumps.
- Sometimes patients need help with breathing for a short time after the drugs have been given, and the patient will have a tube inserted into their airway (endotracheal tube) to connect them to a breathing machine (ventilator).
- Patients are unable to take tablets by mouth or eat unless they are fully conscious, so a nasogastric tube may be inserted (a tube from the nose into the stomach).
- An indwelling urinary catheter will be inserted to measure urine output.
- The patient’s blood and urine are tested frequently to check liver and kidney function, since the drugs used to stop seizures can affect these organs.
- Sometimes an electroencephalogram (EEG) is done, if it is unclear whether the patient has actually had, or is still having a seizure.
- Other tests might be used to look for possible causes for the seizures, such as a head CT scan, or lumbar puncture (to take a sample of spinal fluid to exclude infection).
How long will the patient remain in ICU?
The patient will remain in intensive care while they have investigations and treatment. If they continue to require an endotracheal tube and ventilator, they will continue to be managed in the ICU. Each patient’s condition is very unique and it is important to speak with the medical team caring for the patient to discuss the potential outcome and prognosis.
The information contained on this page is general in nature and therefore cannot reflect individual patient variation. In addition it reflects Australian intensive care practice which may differ from other countries. It is meant as a back up to specific information which will be discussed with you by the Doctors and Nurses caring for your loved one. ICCMU attests to the accuracy of the information contained here BUT takes no responsibility for how it may apply to an individual patient. Please refer to the full disclaimer.
Seizures Version 1
Author Kathleen Ryan CNC ICCMU
Published August 2008