In 75% of all cases where someone has a seizure disorder there is no known cause. From the remaining 25%, the most common reasons are:

- Birth asphyxia
- Sclerosis of the brain
- Infections (Menengitis)
- Brain Tumours
- Head Injury
- Abnormal brain development


What Triggers Seizures:

- Headaches
- Stress and Anxiety
- Changes in blood sugar and oxygen levels
- Changes in lighting (only in cases where the person has a photosensitive seizure disorder which is only 20%)
- Fatigue
- Fog
- Changes in weather / barometric pressure
- Sudden changes in environmental temperature
- Influences of drugs or alcohol
- Hormonal changes
- Diet
- Changes in medication

Neurons are specialized cells in the brain that can transmit electrical signals. These signals are the way that neurons communicate with one another, process information and send messages to other parts of the body. Everything we do, think, say and feel is the result of the electrical signals that are generated by our neurons.

If a group of neurons begin to generate electrical signals in an excessive and highly synchronous way, a seizure can occur. This type of brain activity is called epileptiform activity. A seizure is the result of a brief period of epileptiform activity which may last for a few seconds to a few minutes. The brief period of epileptiform activity can interrupt normal brain function temporarily, however, neurons will resume their normal functions once the seizure comes to an end.

Epileptiform activity can be localized to a very small region of the brain, or can involve many brain networks spread diffusely over a large region. Seizures are classified into two main categories depending on the pattern of epileptiform activity at the onset of the seizure.

- Simple Partial Seizures - Absence - Secondarily Generalized Seizures

- Complex Partial Seizures - Other generalized seizures - Clonic Seizures

- Tonic and Atonic Seizures - Tonic-Clonic Seizures

At the onset of a focal seizure, epileptiform activity is restricted a network(s) of neurons within one hemisphere of the brain.

Simple Partial Seizures

If the region involved is localized, there may be no alteration in awareness and the individual will be able to recall all of the events that occur during the seizure. This is known as a simple partial seizure. The manifestation, or symptoms, of the seizure will depend on which part of the brain is involved. For example, if a focal seizure occurs in the left hemisphere in a region of the brain that controls the index finger, then there may be some uncontrollable movements of the right index finger during the seizure. [Note: each hemisphere of the brain controls movements on the opposite side of the body.] If a region of the brain that processes sound is involved, then the individual may hear sounds that are not really there, or actual sounds may be distorted.

Complex Partial Seizures

If a focal seizure involves more widespread networks within a brain hemisphere, there can be a loss of awareness. This is known as a complex partial seizure. An individual may be unresponsive, and may not be aware of where they are or what they are doing. Semi-purposeful movements of the face (eg chewing or lip smacking) or hands (buttoning clothing) may occur during the seizure.
Epileptiform activity can spread during a focal seizure. Thus, a focal seizure may start with small region of epileptiform activity and could initially be a simple partial seizure which could spread to become a complex partial seizure. In this case, the simple partial seizure is often referred to as an aura.

Click here to see an example of a Complex Partial seizure.

Secondarily Generalized Seizures


It is also possible for a focal seizure to spread so that the other brain hemisphere becomes involved – this would lead to a generalized seizure. However, the type of seizure (focal or generalized) that is present at the onset is important for the correct diagnosis and treatment.

At the onset of a generalized seizure, epileptiform activity involves networks within both hemispheres of the brain. The widespread epileptiform activity associated with generalized seizures results in a sudden loss of awareness or loss of consciousness. There are many types of generalized seizures which are categorized by the type of physical changes that occur during the seizure.

Absence Seizures

Some forms of generalized seizures cause a brief lapse of consciousness without any other signs. This is called an absence seizure, and can often be mistaken for daydreaming because the individual may stare blankly for a just a few seconds. Some types of absence seizures may also cause some physical manifestations such as uncontrollable hand movements or eye blinking.

Click here to see an example of a Absence seizure.

Other generalized seizures

All other types of generalized seizures are associated with some change in the muscles – this may involve muscles in the limbs, and can also involve the trunk muscles and muscles supporting the head. The seizures are categorized by the type of response seen in the muscles.

Tonic and Atonic Seizures

Changes in muscle tone resulting in a sudden body jerk (increased muscle tone) or a sudden fall or head drop (decreased tone) are associated with tonic seizures and atonic seizures, respectively. Often these seizures can be brief (a few seconds) and the individual will regain awareness quickly, however, the potential for injury can be high if atonic seizures are not well-controlled by medication.

Clonic Seizures

Another type of generalized seizures can cause repeated contraction and relaxation of the muscles resulting in a twitching or jerking movement – this is known as a clonic seizure.

Tonic-Clonic Seizures

The most well-known type of generalized seizure is a combination of both tonic and clonic muscle activation, and is called a tonic-clonic seizure. A tonic-clonic seizure is associated with an increase in muscle tone at the onset, which is often associated with a cry as the muscles of the chest wall tighten and force air out of the lungs activating the vocal cords. This is followed by a clonic phase (or rhythmic muscle jerking). A tonic-clonic seizure can last from less than a minute to a few minutes in duration.

Click here to see an example of a Tonic-Clonic seizure.