Seizures look very different in different people, depending on the location of the seizure in the brain. In general, seizures are classified as partial or generalized depending on whether they begin in part of the brain or in the whole brain at once.
Seizures may be subtle or dramatic. A child with absence seizures (formerly known as petit mal) can simply look like they are daydreaming or "spacing out" for a couple of seconds. A child with simple partial seizures may hear a sound that isn’t there, or may twitch in just one arm. A child with tonic-clonic seizures (formerly known as grand mal) will fall to the floor and convulse. A child having a seizure may lose consciousness, or they may be aware of their surroundings and able to talk.
Seizure classification
The old terminology of “petit mal” and “grand mal” seizures was incomplete and not always helpful. The new classification defines seizures as partial or generalized based on whether they begin in part of the brain or in the whole brain at once, with further separation based on the seizure symptoms.
Generalized seizures seem to begin in the whole brain at the same time. They include:
- absence seizures, in which the child briefly stares and does not hear or see what is happening around them
- myoclonic seizures, in which the child has twitches or jerks in all or part of their body
- atonic seizures, in which the child goes limp and falls
- tonic seizures, in which the child goes stiff
- clonic seizures, in which the child jerks rhythmically
- tonic-clonic seizures, in which the child goes rigid, then convulses (shakes or jerks rhythmically)
Partial seizures begin in only a part of the brain; they may remain there, or become secondarily generalized (that is, they may spread out to involve the whole brain). They include:
- simple partial seizures, in which the child is still aware of what is happening around them; these may have motor, somatosensory, autonomic, or psychic symptoms
- complex partial seizures, in which consciousness is impaired
Finally, some seizures may be unclassified because the doctor does not have enough information about what type of seizures they are. With babies, for instance, it may be difficult to tell exactly what type of seizure the baby is having, whether the seizure is partial or generalized, or where it began, because babies’ brains are not yet developed enough to show the clues that appear in older children and adults. Doctors cannot ask babies what they remember about the seizure, and may not be able to tell whether they lost consciousness during the seizure. Seizures in babies are called neonatal seizures.
For more information on all these types of seizures, please click the links on the left.
Status epilepticus
Status epilepticus occurs when a seizure continues for a long time (more than half an hour), or when a child has several seizures without time to recover between them. It can happen with any seizure type.
Seizures in special situations
Not all seizures are caused by epilepsy. Seizures can be provoked by a head injury, lack of oxygen to the brain, a high fever, an infection such as meningitis, drugs, withdrawal from medication, or high blood sugar. These are called provoked seizures.
Febrile seizures, which occur in young children and are provoked by fever, are the most common type of provoked seizures in childhood.
What do different types of seizures indicate?
Different seizure types often indicate different causes or syndromes. For instance, brain injury is more likely to cause partial seizures, while many idiopathic epilepsy syndromes cause generalized seizures. Different seizure types may also be treated differently and have different prognoses.
Nearly three-quarters of children have had more than one type of seizure. For example, children with juvenile myoclonic epilepsy often have both myoclonic and generalized tonic-clonic seizures at different times.
One seizure may progress to a different type of seizure; for instance, partial seizures may become generalized, or a myoclonic seizure may progress to a generalized tonic-clonic seizure.
