Seizure disorders – including epilepsy

What is a seizure?

Anyone can have a seizure in the right circumstances, however not everyone who has seizures has epilepsy. A seizure is the result of a sudden, uncontrolled electrical discharge in a group of brain cells (neurons). For a brief period, this abnormal activity in the brain causes varied symptoms: strange sensations, emotions, convulsive movements, uncharacteristic behavior, altered awareness and/or loss of consciousness.

About seizures

Seizures occur when there is a momentary ‘imbalance’ within electrical and chemical circuits in the brain, such that groups of brain cells act in an excessive fashion. This may create a temporary disturbance in the way the brain controls awareness and responsiveness and may cause unusual sensations or abnormal movements and postures. What happens during a seizure reflects what parts of the brain are involved.

There are many different types of seizures, but the major distinction that doctors try to make is between focal seizures, where the seizure arises in one part of the brain (usually on one side of the brain) and generalised seizures, where epileptic activity begins all over the brain (on both sides of the brain) simultaneously.

Focal seizures 

Focal seizures occur when the seizure arises in a localised part of the brain, usually on one side. Focal seizures used to be called partial seizures. Consciousness may or may not be impaired. The manifestations of a focal seizure depend on the part of the brain involved with the abnormal brain cell activity. Focal seizures used to be classified according to whether there is impairment of consciousness or not.

Focal seizures without impaired consciousness

Formerly called simple partial seizures, these arise in parts of the brain not responsible for maintaining consciousness, typically the movement or sensory areas. Consciousness is NOT impaired and the effects of the seizure relate to the part of the brain involved. If the site of origin is the motor area of the brain, bodily movements may be abnormal (e.g. limp, stiff, jerking). If sensory areas of the brain are involved the person may report experiences such as tingling or numbness, changes to what they see, hear or smell, or very unusual feelings that may be hard to describe. Young children might have difficulty describing such sensations or may be frightened by these.

Focal seizures with impaired consciousness

Formerly called complex partial seizures, these arise in parts of the brain responsible for maintaining awareness, responsiveness and memory, typically parts of the temporal and frontal lobes. Consciousness is lost and the person may appear dazed or unaware of their surroundings. Sometimes the person experiences a warning sensation or ‘aura’ before they lose awareness , essentially the simple partial phase of the seizure. Behaviour during a complex partial seizure relates to the site of origin and spread of the seizure. Often the person’s actions are clumsy and they will not respond normally to questions and commands. Behaviour may be confused and they may exhibit automatic movements and behaviours e.g. picking at clothing, picking up objects, chewing and swallowing, trying to stand or run, appearing afraid and struggling with restraint. Colour change, wetting and vomiting can occur in complex partial seizures.

Following the seizure the person may remain confused for a prolonged period and may not be able to speak, see, or hear if these parts of the brain were involved. The person has no memory of what occurred during the complex partial phase of the seizure and often needs to sleep.

Focal seizures becoming bilaterally convulsive

Focal seizures may progress due to spread of epileptic activity over one or both sides of the brain. Formerly called secondarily generalised seizures, bilaterally convulsive seizures look like generalised tonic-clonic seizures. 

The distinction between simple and complex partial seizures is often unclear and the terminology may be confusing. For these reasons those terms are falling out of favour and more descriptive terminology is used for focal seizures.

Generalised seizures 

Generalised seizures occur when epileptic activity begins all over the brain simultaneously. Consciousness is always impaired in generalised seizures.

Tonic-clonic seizures

Tonic-clonic seizures produce sudden loss of consciousness, with the person commonly falling to the ground, followed by stiffening (tonic) and then rhythmic jerking (clonic) of the muscles. Shallow or ‘jerky’ breathing, bluish tinge of the skin and lips, drooling of saliva and often loss of bladder or bowel control generally occur. The seizures usually last a couple of minutes and normal breathing and consciousness then returns. The person is tired following the seizure and may be confused.

Absence seizures

Absence seizures produce a brief cessation of activity and loss of consciousness, usually lasting 5-30 seconds. Often the momentary blank stare is accompanied by subtle eye blinking and mouthing or chewing movements. Awareness returns quickly and the person continues with the previous activity. Falling and jerking do not occur in typical absences.

Myoclonic seizures

Myoclonic seizures are sudden and brief muscle contractions that may occur singly, repeatedly or continuously. They may involve the whole body in a massive jerk or spasm, or may only involve individual limbs or muscle groups. If they involve the arms they may cause the person to spill what they were holding. If they involve the legs or body the person may fall.

Tonic seizures

Tonic seizures are characterised by generalised muscle stiffening, lasting 1-10 seconds. Associated features include brief cessation of breathing, colour change and drooling. Tonic seizures often occur during sleep. When tonic seizures occur suddenly with the child awake they may fall violently to the ground and injure themselves. Fortunately, tonic seizures are rare and usually only occur in severe forms of epilepsy.

Atonic seizures

Atonic seizures produce a sudden loss of muscle tone which, if brief, may only involve the head dropping forward (‘head nods’), but may cause sudden collapse and falling (‘drop attacks’).

From these descriptions, it can be appreciated that the exact type of seizure may be difficult for a witness to determine. For example, a seizure with stopping and staring could be a complex partial (focal) seizure or an absence (generalised) seizure. A convulsive seizure may be a generalised tonic-clonic seizure or focal seizure which became bilaterally convulsive. A sudden fall to the ground (‘drop attack’) can occur with myoclonic, tonic or atonic seizures or a focal seizure involving the movement areas. Determination of the exact type of seizure is important and is obtained from patient and observer descriptions, home video recordings, EEG testing and sometimes video EEG monitoring.

It is also important to remember that many episodic behaviours and disorders in children can mimic epilepsy, including breath holding spells, sleep movements, day dreaming, fainting, migraine, heart and gastrointestinal problems, and psychological problems.

What is epilepsy?

A single seizure does not necessarily mean a person has epilepsy. For example a single seizure can occur if a person has a bang to their head.

Epilepsy is a condition whereby an individual has a tendency to have recurrent seizures; the reasons why individuals may have this tendency differ from individual to individual. Epilepsy is a health condition, it is not a disease, it is not contagious and it is not a psychological disorder.

How common is epilepsy?

Many people in the community have seizures. About 1 in 20 children (5%) will have a seizure of some form during childhood. About 1 in 100-200 children (0.5-1%) have epilepsy, a neurological condition where children have a predisposition to recurrent, unprovoked seizures.

How is epilepsy diagnosed?

The diagnosis of epilepsy is based on the doctor clarifying that your young person has epileptic seizures and that these have a tendency to recur. Your doctor will ask questions to determine if your young person is having recurrent epileptic seizures and to obtain information about the detail of the seizures that are occurring. Sometimes this requires information from others who have seen the seizures first hand. The diagnosis is made primarily using the doctor’s clinical judgment regarding the information given to them about what has been occurring. If safe to do so (for example if there is a second person present during a seizure), it can be very helpful to take videos of the seizures and show these to the doctor to ensure that they have optimal information for their assessment. Other tests such as EEG or MRI are more helpful to look at the underlying causes of epilepsy, after the diagnosis has been made using the doctor’s clinical judgement.

What causes epilepsy?

Epilepsy, having a risk of recurrent seizures, has different causes in different individuals. Broadly the following are possible causes of epilepsy:

• Genetic factors, these are a common causes of epilepsy, many genetic factors are not inherited as they are new genetic changes that occur in the individual with epilepsy, others are ‘susceptibility factors’ meaning that the genetic make-up alone does not definitely mean that seizures will occur in every individual with this genetic make-up in a family, but the genetic factors increase the risk of seizures. Approximately 70% of epilepsies are due to genetic factors. Doctors do not routinely test for many of these genetic factors, as most testing is not available outside of research studies. However, there are recognized patterns of seizures and findings on EEG in epilepsies that are likely to be genetic in their basis and these patterns may allow the doctor to diagnose the epilepsy as genetic. Please check with your doctor if you think the cause of the epilepsy is ‘unknown’ as in many instances, these epilepsies are still understood by doctors as being due to genetic influences. 

• Abnormal areas of brain formation (structural malformations), often these are present from when the brain developed during fetal life. Sometimes these areas of abnormal brain may be small or hard to see and high resolution MRI with expert review may be required to detect them. Speak to your doctor if this may be relevant (if there are focal seizures) for your young person. 

• Brain injury e.g. trauma, stroke, meningitis 

• Immune disorders that cause inflammation in the brain

• Metabolic disorders, resulting in imbalance in chemicals within the brain 

• Unknown, despite all tests that are currently available some epilepsies still are not able to linked to an underlying cause.

Understanding the underlying cause of the epilepsy will give your doctor a better idea as to whether or not your young person might grow out of their epilepsy. This can happen for some epilepsies, but not for all of them.

What investigations are needed?

EEG

An EEG measures the electrical activity in the brain. During an EEG, electrodes (small metal recording disks) are applied to specific locations on the scalp and record this activity. An EEG is a painless procedure. Epilepsies with different causes have different patterns on EEG. For example epilepsies that are genetic generalized epilepsies typically have generalized spike-and-wave patterns, epilepsies that start in one part of the brain (focal) have localized abnormalities seen in electrodes over that part of the brain. An EEG is not typically used to diagnose epilepsy; this is because some EEG abnormalities can be seen in healthy members of the population without epilepsy. But looking at the EEG patterns in an individual with epilepsy can be helpful in understanding which cause of epilepsy they are likely to have. An EEG can only diagnose epilepsy if a seizure occurs during the EEG recording.

VEM

Children with uncontrolled epilepsy sometimes undergo detailed EEG called video EEG monitoring or VEM.

MRI

An MRI is a scan that uses magnetic fields instead of radiation to obtain high quality images of the brain. It is not always necessary, especially if the epilepsy is thought to be due to a genetic condition.

Other investigations

Other tests may be required, such as blood tests. These may be done to exclude other conditions or for specific epilepsies e.g. genetic epilepsies.

Treatments

Children with seizures do not always need treatment. In many instances, explanation and reassurance by the doctor and advice about safety precautions and first aid management for possible future seizures is all that is required. Many children with epilepsy have only a single seizure and do not require medication.

For children with recurrent seizures, the decision to prescribe medication depends on the type of epilepsy and seizure, the age of the child, the presence of associated developmental and behavioural problems, and the attitudes and lifestyle of the child and family. Medical treatment usually means prescription of antiepileptic medication to prevent further seizures, but occasionally medication is prescribed to treat seizures only when they occur.

General treatment options for children with epilepsy include:

For children with uncontrolled epilepsy, that is epilepsy in which seizures are not adequately controlled by medication, other treatments are available, including: