The Brain
Regions of the brain
What is epilepsy?
Seizure types
What seizures look like

The Human Brain and Seizures

The human brain is the most complex organ in the body. It is made up almost entirely of nerve cells.

At any given moment there are millions of electrical impulses running through the brain. The brain is constantly receiving and responding to hundreds of messages from the environment and the internal organs of our body.

A seizure is a disruption in the normal pattern of these electrical impulses in the brain, caused by the brain cells firing simultaneously at a much faster rate.

Depending on where a seizure starts and spreads in the brain, they can result in changes in:

• Sensation,
• Awareness or consciousness,
• Behaviour,
• or Movement

Some seizures are severe and recognised as a seizure, whilst others are subtle and may not be noticed by most people.

For more in-depth information about the brain see Getting Our Heads Around the Brain

Regions of the brain

Brain Stem
All areas of the nervous system connect with the brain stem. It regulates heart rate, breathing, blood pressure, digestion, sweating, level of alertness and ability to sleep. It also contains reflex centres that control swallowing, coughing, sneezing and vomiting.

Cerebellum
The cerebellum is responsible for co-ordination, and maintaining of posture, muscle tone, and balance.

Cerebrum
The largest structure of the brain is the cerebrum and contains lobes including frontal, parietal, occipital, and temporal lobes. It is the centre of intellect, memory, language and consciousness, receiving and interpreting sensory information and controlling movement.

Basic functions of the lobes

Frontal lobe
Concentration, memory, decision making, judgement, emotional response, impulse control, language, voluntary movement, how we know what we are doing within our environment (consciousness).

Parietal lobe
Touch, temperature and pain perception (sensation), awareness of body and where it is in space.

Temporal lobe
Hearing ability, memory, interpreting language, some visual perceptions, behaviour.

Occipital lobe
Vision

When a seizure occurs, the part of the body affected can sometimes be traced back to a specific area within the brain where excess electrical activity is taking place. A seizure may alter behaviour, consciousness, movement, perception and/or sensation.

For more detailed information about the human brain, click The secret life of the brain.

For more information on other brain disorders,
Brain Foundation of Australia
Brain Dynamics Centre

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What is epilepsy?

Epilepsy is a disruption of the normal electrochemical activity of the brain that results in seizures. Under certain circumstances anyone can have a seizure. It is only when there is a tendency to have recurrent seizures (more than one) that epilepsy is diagnosed.

Seizure Types

There are 40 different types of seizures.

Seizures can be divided into two major groups: partial seizures and generalised seizures.

1 Partial seizures
About 60% of people with epilepsy have partial seizures, also known as focal seizures. These seizures can often be subtle or unusual, and may go unnoticed or be mistaken for anything from intoxication to daydreaming. Seizure activity starts in one area of the brain and may spread to other regions of the brain. Types of partial seizures are:

• Simple Partial (no loss of awareness)
• Complex Partial (change in awareness and behaviour)
• Secondarily Generalised Tonic-Clonic* (see note below)

2 Generalised seizures
Generalised seizures are the result of abnormal activity in the whole brain simultaneously. Because of this, consciousness is lost at the onset of the seizure. There are many types of generalised seizures.

• Generalised Tonic-Clonic
• Absence
• Myoclonic
• Tonic
• Atonic

*Note: Sometimes a seizure starts as a partial seizure and then becomes a generalised seizure - almost always a tonic-clonic seizure. When this occurs, the seizure is called secondarily generalised.

Most people will only have one or two seizure type(s), which may vary in severity. A person with severe epilepsy or significant damage to the brain may experience several different seizure types.

Here is a simple diagram showing how seizures are classified:

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What seizures look like

These are also called focal seizures and were previously referred to as ‘petit mal’.

Simple Partial Seizures These seizures are often called an ’aura’ or warning by the person experiencing them as they can precede a complex partial or tonic clonic seizure. There is no loss of awareness or consciousness and they are usually short-lived, lasting less than a minute. Examples of symptoms are: Sensory – numbness, tingling or burning sensation in a region of the body Motor – jerking of a limb, twitching of the face Autonomic – blushing, pallor, increased heart-rate, nausea Psychic – deja'vu, hallucinations (visual, sound, taste or smell), emotions such as fear Complex Partial Seizures Here consciousness or awareness is altered, producing a vague, confused or dreamlike appearance. The person may respond, but often inappropriately, and display strange, random or repetitive behaviour. This behaviour commonly presents as chewing, fidgeting, taking off clothes, walking around or mumbling. After the seizure, there is often a period of confusion and little, if any, memory of the event. These seizures last approximately 30 seconds to three minutes.

Generalised Tonic Clonic Seizures
Generalised tonic-clonic seizures were previously referred to as ‘grand mal’ and are sometimes called a fit or convulsion. They are the most universally recognised seizures.

They often begin with a sudden cry. If standing, the person will fall to the ground and lose consciousness.

The body becomes quite stiff (tonic) shortly followed by jerking of the muscles (clonic). Breathing is shallow or temporarily suspended causing the lips and complexion to look grey/bluish. Saliva (sometimes also blood if the tongue has been bitten) may come out of the mouth, and there may be loss of bladder control.

The seizure usually lasts approximately two minutes and is followed by a period of confusion, agitation and extreme tiredness. Headaches and soreness are also common afterwards.

Absence Seizures
These seizures, previously referred to as ‘petit mal’, almost always begin in childhood and are commonly mistaken for daydreaming and inattentiveness.

They are characterised by staring, loss of facial expression, unresponsiveness, cessation of activity and eye blinking or upward eye movements.

They start and end abruptly, and last approximately two to 20 seconds. Most people recover their mental function immediately and return to their previous activity, with no memory of the event.

Children who have absence seizures often have normal cognitive function and intelligence, although if the condition is not treated it can create gaps in learning due to the seizures occurring many times a day.

Myoclonic Seizures
These are brief but significant muscle jerks which usually involve the upper body but can involve the lower or whole body. The person may drop or spill what they are holding or fall off a chair. There is no impairment of consciousness, but if several seizures occur over a short period of time the person may feel slightly confused or drowsy. These seizures frequently occur shortly after awakening.

Tonic Seizures*
These are a brief stiffening of the muscles of the whole body which cause it to go rigid. If a person is standing, they will fall rapidly to the ground. Recovery is swift, but injuries can be sustained. These seizures can also occur in sleep.

Atonic Seizures*
Atonic seizures are a sudden, brief loss of muscle tone of the whole body. Once again, the person will abruptly collapse to the ground, usually head first, so facial and head injuries are common. There is no noticeable loss of consciousness and the person usually recovers swiftly unless injured.

*Note: Tonic and Atonic seizures are also known as drop attacks and are more likely to occur in people with severe epilepsy and multiple seizure types.

The majority of people with epilepsy achieve good control through the use of antiepileptic medication and many become seizure free. With regular medication and a sensible lifestyle a full and active life is possible.

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For more information or advice about epilepsy, contact Epilepsy Action on 1300 37 45 37 or email epilepsy@epilepsy.org.au