Seizures can be described by which part or parts of the brain the epileptic activity starts in. The three groups are: partial (also called focal), secondary generalised, and generalised. Partial seizures involve epileptic activity in just a part of the brain. Partial seizures can be divided into simple partial and complex partial. In a simple partial seizure the person is fully conscious. They remain fully aware of their surroundings, despite seizure activity In a complex partial seizure a person partly loses consciousness and they are not aware of what they are doing. Because of this, they may not remember the seizure afterwards, or their memory of it will be unclear. Generalised seizures involve epileptic activity in both halves of the brain. The person loses consciousness during the seizure. Sometimes, the epileptic activity that starts as a partial seizure can spread to the rest of the brain. When this happens, the seizure is known as secondary generalised.

Partial Seizures:
Simple partial seizures (SPS - formerly known as focal seizures) are characterised by strange or unusual sensations, for example odours or visual abnormalities. Other characteristics of SPS include sudden or restless movement, hearing distortion, stomach discomfort, and a sudden sense of fear. Alteration of consciousness or memory is generally not associated with simple partial seizures. As mentioned before, partial seizures are localised to one region of the brain. Each region of the brain is responsible for certain body functions, sensations, and movements. By observing the motor manifestations and sensory responses during SPS, the neurologist may be able to determine the brain region affected. This may help determining which drugs are best for the treatment of each individual’s epilepsy. The ICES has categorised simple partial seizures into 4 main categories, motor, sensory, psychic, and autonomic – each category has several types of SPS.

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Complex partial seizures (CPS - formerly psychomotor or temporal lobe seizures) are often preceded by an “aura.” They are usually identified by the manifestation of complicated motor and sensory action. The person can appear dazed and confused – random walking, mumbling, head turning, or pulling at clothing may be observed. These repeated idiosyncratic motions are often called automatisms and are usually not recalled by the person. There may be some change in consciousness or memory. In children, this seizure should not be confused with the absence seizures described below. CPS often originate in the temporal or frontal lobes of the brain.

Generalized Seizures:
Generalised absence seizures (formerly petit mal) are characterised by a complete loss of awareness. The person may stare into space and appear to be daydreaming or of in a daze. Absence seizures are not preceded by a warning (aura) and are followed by normal activity by the individual. There is very minimal movement during the actual seizure so it may go unnoticed by others.
These seizures often occur in children, however they can develop into other types of seizures. Absence seizures usually diminish into adulthood.
There are two type of absence seizures;

  • Typical Absence Seizures which are non-convulsive and muscle tone is usually preserved, usually lasting for less than 10 seconds, and
  • Atypical Absence Seizures which are longer in duration, may or may not show a loss in muscle tone and often include tonic/clonic-like movements.

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Tonic-clonic seizures (formerly grand mal) is a generalised convulsion occurring in two phases. In the tonic phase, there is stiffening of the muscles, the person loses consciousness and falls, as the body grows rigid. In the clonic phase, body extremities jerk and twitch. The seizure event may often be ended by another tonic phase.
After the seizure, consciousness returns slowly. When the person wakes up, they are often confused or disoriented. This seizure, while perhaps the type of epilepsy most visible in the public mind, is not the most common. Approximately two-thirds of people with epilepsy have complex partial seizures. A secondary generalised tonic-clonic seizure begins locally (with partial seizure) and it may be preceded by an aura.

Other types of seizures include:

  • Myoclonic Seizures, often associated with single or repetitive jerking motions of the muscles (myoclonus). There is no loss of consciousness during this type of seizure. Myoclonic seizures are primarily observed in young children and infants, and are more rare in adults.
  • Atonic Seizures, often called drop attacks/seizures. These seizures are characterised by sudden loss of muscle tone, resulting in an inability to sit or stand. Atonic seizures are usually rare in adults: they are often identified in children with Lennox-Gastaut Syndrome. While the actual seizures cause little injury to the child, most resulting harmful injuries after the event are usually related to the child falling or injuring his/herself when they lost muscle tone.
  • Photosensitive seizures, which are the result of a light-related stimulus that may induce the triggering of a seizure. Photosensitive seizures are often classified under the heading of “reflex epilepsy.” They usually occur around the ages 8-20 with a higher frequency of cases during puberty. They may be triggered by both natural and artificial light in oscillating or moving patterns.

Status epilepticus describes a state of recurring seizures in which consciousness does not return in between the seizure events. If a seizure does not stop within 5-10 minutes, call for help. The individual may be in danger of going into status epilepticus, a potentially life-threatening event.
For any seizure event that appears to be different than those normal for the individual or lasts abnormally long help should be called. This demands immediate medical care, as it can lead to severe brain damage and even loss of life.

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