SEIZURE ONSET

FOCAL vs GENERALIZED

 

What is a Focal Onset Seizure?

Seizures that start focally, which means involving networks in one hemisphere of the brain are considered to be FOCAL ONSET SEIZURES. Focal onset seizure replaces the prior term “partial seizure”.

A focal onset seizure can be further classified by the level of awareness a person has when they are experiencing the symptoms of a seizure. Thus, focal seizures are subdivided into categories depending on the person’s level of awareness, AWARE vs IMPAIRED AWARENESS. The focal aware seizure replaces the previously used term “simple partial seizure” and the focal impaired awareness seizure replaces the term “complex partial seizure”.

Sometimes it is difficult to know for certain if a person has impaired awareness and in these cases a focal seizure might just be described by the motor symptoms which the person may or may not experiences during a seizure. The type of symptoms the person experiences would help to then classify a seizure as MOTOR vs NON-MOTOR.

The types of seizures described as FOCAL Motor Onset seizures include:

Automatisms

Atonic

Clonic

Epileptic spasms

Hyperkinetic

Myoclonic

Tonic

The types of seizures described as FOCAL Non-Motor Onset include:

Autonomic

Behavior arrest

Cognitive

Emotional

Sensory

Focal seizures which start on one side of the brain can also spread as a seizure progresses to involve both sides of the brain and cause symptoms on both sides of the body in some instances. These seizures are now described as “focal to bilateral tonic clonic-seizures”. In the past a seizure that started focally, in one part of the brain, and spread to involve both hemispheres of the brain was referred to as a “secondarily generalized tonic clonic seizure”.  In the new classification of seizure types the term “generalized” refers only to seizures which are generalized from the onset (beginning). Generalized onset seizures can also be described as Motor or Non-Motor.  

What is a Generalized Onset Seizure? 

Seizures that begin in both hemispheres of the brain are called generalized seizures. Generalized seizures can be further classified as motor or non motor seizures.  

A generalized tonic clonic seizure is a seizure which is used to describe seizures with changes in motor activity. These seizures present with stiffening (tonic) and jerking (clonic) changes in muscle activity. These are often referred to as “grand mal” seizures.

The types of generalized seizures described as generalized onset motor are:

Tonic-clonic

Clonic

Tonic

Myoclonic

Myoclonic-tonic-clonic

Myoclonic-atonic

Atonic

Epileptic spasms

A generalized absence seizure are characterized as seizures in which a person has a brief change in awareness. These are considered generalized onset non motor seizures. Other symptoms which may be seen with a generalized absence seizure are staring, automatic or repeated movements like lip smacking. Absence seizures are further classified as typical and atypical and you can read more about absence seizures here: (link to absence page)

The types of generalized seizures described as generalized onset non motor are:

Typical

Atypical

Myoclonic

Eyelid myoclonia