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New Classifications of Seizures and Epilepsies Include New Seizure Types, Simpler Terms


Revised classifications of seizures and epilepsies released in March by the International League Against Epilepsy include clearer terms that will help patients better communicate with doctors and doctors better communicate with each other, experts say.

In an effort to make diagnosis and classification of seizures more accurate for both physicians and patients, the International League Against Epilepsy (ILAE) has revised its classifications of seizures and of epilepsy disorders for the first time since 1981.

The new classifications, published in two papers in the March 9 Epilepsia, include new seizure types not described in the previous ILAE classifications; enable classification of a seizure even if the onset is unobserved and/or unknown; and adopt more transparent terms, replacing those that were confusing to patients and non-epilepsy specialists, such as “complex partial” or “psychic” seizures.

“Although the previous classifications were familiar to a lot of doctors, they had certain problems that were worth fixing,” said Robert S. Fisher, MD, PhD, FAAN, the Maslah Saul Professor of Neurology at Stanford University and director of the Stanford University Epilepsy Center, who led the task force that drove the formation of the revised seizure classifications. “If you woke up and saw someone shaking in bed and we could tell exactly what kind of seizure it was, you still couldn't officially call it a type if you missed the beginning. And some terms were opaque, even for many doctors. As a result, seizures were often getting misnamed. So we tried to make terms more transparent to patients and specialists.”

The revision maintained the fundamental division of seizures into focal onset (those that involve circuits in just one hemisphere of the brain) and general onset (those that involve both hemispheres), Dr. Fisher said.

The classifications of focal seizure types include the option to specify the patient's level of awareness in simpler terms (as “aware” or “impaired awareness,” replacing the terms “simple partial” and “complex partial,” respectively). Focal seizures can also specify motor function (as “motor” or “non-motor”). [For more information on the updated classifications, see [“The ILAE's Updated Classifications of Seizures and Epilepsies.”]

The transparency of seizure terminology was one of the task force's primary goals in revising the classifications, said Jacqueline A. French, MD, FAAN, professor of neurology at New York University Comprehensive Epilepsy Center, who was a coauthor on both papers.

“The terms that epileptologists use for seizures really don't make a lot of sense; they don't have a lot of face validity,” Dr. French said. “So if I as a doctor say to you, ‘You have complex partial seizures,’ you can't get anything out of that. You have no idea what that means; it doesn't convey any information. And similarly, if you're a gastroenterologist, if you have a patient who comes in and he says, ‘I have complex partial seizures,’ that term itself doesn't convey information.

“We wanted to revise the classifications so if you say, I have focal seizures with impaired awareness, the meaning is pretty clear. It means the seizure comes from a focus – a specific part of the brain – and impaired awareness means what it sounds like. We believed the terms should mean something to patients and other doctors.”

The impact of the classifications will be widespread, although this may take time, Dr. Fisher said. “These terms will be used to describe seizures universally. Journal editors will require people to describe seizures in these terms for published articles. Insurance companies and ICD codes will presumably use these terms.”

Dr. French said that the task force expects that the editors of major epilepsy journals will be looking to ensure that the new and proper terminology is used in studies. In addition, they expect the common data elements for National Institute of Health studies and registries will incorporate the new classifications. “When people collect data in studies, they'll have to use them,” she said.

Resources are available to help doctors get on board, Dr. French noted. She cited a website,, created by ILAE, that explains all of the different seizure and epilepsy classifications, discusses the different etiologies, provides videos, and enables people to ask questions.

But despite the clarity the updates should bring to seizure terminology, Dr. Fisher said, “We were unable to do what we had really hope to do: to derive a classification based on scientific principles explaining fully why there are different seizure types based on a thorough understanding of their underlying pathophysiology. We don't know enough to do that yet. That's why we used the word ‘operational’ in the title [of the papers]. What we did was make relatively minor tweaks to the existing system.”


Updates to the 1981 classifications were very much needed, several independent experts agreed in separate interviews with Neurology Today.

“These updates are overdue,” said Joseph Sirven, MD, FAAN, professor and chair of neurology at the Mayo Clinic in Phoenix, Arizona. “There is so much we are learning about epilepsy – its genetics, the mechanisms that underlie the disease – that we are overdue in creating a classification that can incorporate these new understandings.”

Allan Krumholz, MD, professor emeritus of neurology at the University of Maryland and first author of the AAN's current evidence-based clinical practice guidelines on management of a first seizure and evaluation of a first seizure, agreed. “A lot has changed over the last 30-35 years in terms of how we understand seizures and how they develop and evolve. It was worthwhile reconsidering this.”

However, he said, “I wouldn't really look at it as a major change but more of an evolution. Mainly, this is an effort that helps us communicate better with patients and with each other — epileptologists to other specialists, physicians to nurses, etc.”

The new classification will also be helpful for patients, the experts said. “We can say to a patient, ‘You have this type, and patients with your type seem to do better with X, Y, or Z medication,” Dr. Krumholz said. Neurologists can also offer better prognostic information, he said, by saying, for example, that a particular seizure type has an excellent prognosis, or advising them that if they take their medication, they'll likely do great with that type of seizure.

“These new terms we use for a seizure should help patients understand how seizures are actually affecting them – for example, if they are having focal impaired awareness seizures, they'll understand why they can't drive,” Dr. Krumholz continued. “Clear communication will help patients understand their condition and its limitations and promote better seizure control, self-management, and communication skills with their families and other physicians.”

Both experts agreed that the guidelines can, and should, continue to evolve, especially as researchers learn more about the etiology of epilepsy.

“Right now, epilepsy is a clinical diagnosis supported by electrical recordings of the brain,” Dr. Krumholz said. “But we're learning many seizure disorders have very specific genetic footprints. As we learn more about those, the terminology and definitions may change again because we may be classifying things not just on the way they look clinically and on EEG but also on the underlying pathophysiology. We have to be open to changing out classifications. I see this as an evolving process.”


The process of creating revised classifications has been decades in the making. The wheels began turning more than 15 years ago when the ILAE “started the process of clearing up the terminology for epilepsy” and formed various task forces to try to achieve a consensus for the classification committee, said Robert S. Fisher, MD, PhD, FAAN, the Maslah Saul Professor of Neurology at Stanford University and director of the Stanford University Epilepsy Center.

“Getting consensus on seizure classifications turned out to be very difficult,” he said, noting that in the absence of a true scientific classification of seizures, “there's no right or wrong way to do it.”

The final version of the guidelines incorporated opinions from experts and the public and received final approval by the ILAE executive committee before being submitting to the peer-reviewed journal, Epilepsia. Notable updates include:

  • Seizures are separated based on where they begin in the brain. Focal seizures have onset in one hemisphere of the brain, while generalized seizures engage both hemispheres at onset.
  • For focal seizures, the next classifier is level of awareness.
    • “Focal aware” replaces the term “simple partial.” A seizure is “focal aware” if the person's awareness is intact, even if they are unable to talk or respond during the seizure.
    • “Focal impaired awareness” replaces the term “complex partial.” A seizure is “focal impaired awareness” if the person's awareness is impaired at any time.
  • Next, focal seizures are described in terms of motor symptoms.
    • In a “focal motor onset seizure,” some type of movement – whether twitching, jerking, or stiffening – occurs during the seizure. Focal motor onset seizures include automatisms, atonic, clonic, epileptic spasm, hyperkinetic, myoclonic, and tonic seizures.
    • In a “focal non-motor onset seizure,” only non-motor symptoms – including changes in emotions, sensations, or thinking – occur. Focal non-motor onset seizures include autonomic, behavior arrest, cognitive, emotional, and sensory seizures.
  • “Generalized tonic-clonic seizure” is still used to describe seizures with stiffening (tonic) and jerking (clonic), replacing the old term “grand mal.”
  • “Generalized absence seizure” involves brief changes in awareness and may involve repeated or automatic movements, such as lip smacking. This term replaces the old term “petit mal.”
  • New seizure types, such as myoclonic-tonic-clonic or myoclonic-atonic, are included.
  • Unknown seizures are those that physicians cannot designate as having focal or generalized onset with about 80 percent certainty. Physicians can now describe a seizure with an unknown onset as tonic-clonic, behavior arrest or epileptic spasms.


• Fisher RS, Cross JH, French JA, et al. Operational classification of seizure types by the International League Against Epilepsy: Position paper of the ILAE commission for classification and terminology Epilepsia 2017; Epub 2017 Mar 8.
    • Scheffer IE, Berkovic S, Capovilla G, et al. ILAE classification of the epilepsies: Position paper of the ILAE commission for classification and terminology Epilepsia 2017; Epub 2017 Mar 8.
      • Fisher RS, Cross JH, D'Souza C, et al. Instruction manual for the ILAE 2017 operational classification of seizure types Epilepsia 2017; Epub 2017 Mar 8.