Epileptic Seizure

An epileptic seizure is a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

Epilepsy

Epilepsy is a disease characterized by an enduring predisposition to generate epileptic seizures and by the neurobiological, cognitive, psychological, and social consequences of this condition.


The diagnosis of epilepsy requires at least one of the following criteria:


  1. At least two unprovoked (or reflex) seizures occurring greater than 24 hours apart.
  2. One unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years.
  3. Diagnosis of an epilepsy syndrome.

Epilepsy is considered to be resolved for individuals who had an age-dependent epilepsy syndrome but are now past the applicable age or those who have remained seizure-free for the last 10 years, with no seizure medication for the last 5 years.


Status epilepticus

Status epilepticus (SE) is either 1) continuous seizure activity or 2) two or more sequential seizures without full recovery of consciousness between seizures, that last more than a defined time period. The time period is defined as:

  • 5 minutes for generalized tonic-clonic seizures
  • 10 minutes for focal seizures
  • 10 to 15 minutes for absence seizures

A previous definition of SE used a universal 30 minute time period, based on the duration of convulsive status epilepticus that may lead to permanent neuronal injury by itself.


Seizure classification

  • A. Focal
    • Awareness might be preserved or impaired
    • Motor or non-motor
    • Focal to bilateral tonic-clonic
  • B. Generalized
    • Awareness is impaired
    • Motor (tonic-clonic, tonic, clonic, atonic, myoclonic, negative myoclonic, myoclonic-atonic, epileptic spasms)
    • Non-motor (typical absence, atypical absence, myoclonic absence, eyelid myoclonia with/without absence)
  • C. Unknown
    • Awareness might be preserved or impaired
    • Motor (tonic-clonic or other)
    • Non-motor (absence)
  • D. Unclassified

For generalized seizures:


  • Motor symptoms may include sustained rythmical jerking (clonic) movements, muscles becoming weak or limp (atonic), muscles becoming rigid (tonic), brief muscle twitching (myoclonic), or epileptic spasms (repeated body flexion or extension)
  • Non-motor seizures are usually called absence seizures. May be typical with sudden onset, usually lasting less than 10-20 seconds, followed by brief confusion, or atypical with slower onset and longer duration. May include brief twitches (myoclonus) that affect specific parts of the body (eg. eyelids).

For focal seizures:


  • Motor symptoms may also be clonic, atonic or myoclonic or take the form of automatisms, repeated automatic movements like hand clapping or rubbing, running, lip smacking, or chewing.
  • Non-motor symptoms may be changes in sensation, emotions, thinking or cognition, autonomic functions (such as gastrointestinal sensations, waves of heat or cold, goosebumps, heart racing, etc.), or lack of movement (behavioral arrest).

For unknown onset seizures:


  • Motor seizures may be tonic-clonic or epileptic spasms
  • Non-motor seizures usually include behavioral arrest.




References

  • Updated classification of epileptic seizures: Position paper of the International League Against Epilepsy Epilepsia. 2025 Apr 23. doi: 10.1111/epi.18338