For much of modern medical history, epilepsy was commonly described using a simple pair of French terms: grand mal and petit mal.
Grand mal referred to the dramatic major convulsion. Petit mal referred to smaller or less visibly dramatic attacks.
The language was memorable, easy to teach and widely used. It was also fundamentally limited.
As physicians learned more about focal seizures, absence seizures, EEG patterns, epilepsy syndromes and seizure networks, the old major-versus-minor framework became increasingly unable to describe what clinicians were actually seeing.
The history of seizure classification is therefore a history of medicine repeatedly discovering that outward appearance alone is not enough.
This page follows that change from severity-based labels to the modern international classification of focal, generalised, unknown and unclassified seizures. The separate history of absence terminology is covered in greater detail elsewhere on this site.
Why ‘grand’ and ‘petit’ made sense historically
Before EEG, neuroimaging and modern neuroscience, physicians classified seizures mainly by what they could observe.
A person who suddenly lost consciousness, became rigid and then developed bilateral convulsive movements presented an obvious, unmistakable event.
A person who briefly stared, paused or experienced a smaller motor disturbance presented something much less dramatic.
It was therefore natural for nineteenth-century classifications to distinguish major from minor attacks.
The problem was that visual severity does not tell us where a seizure starts, how it spreads or which epilepsy syndrome it belongs to.
Esquirol and the language of major and minor attacks
Jean-Étienne Dominique Esquirol is closely associated with the nineteenth-century use of grand mal and petit mal.
The terms fitted a wider medical habit of ranking epilepsy attacks by visible magnitude.
A large convulsion belonged at one end of the spectrum; a brief lapse or minor event belonged at the other.
The system was useful descriptively, but it encouraged the idea that seizures existed mainly on a scale of ‘big’ to ‘small’.
That assumption would become increasingly difficult to defend.
The first problem: focal seizures
Nineteenth-century clinicians, especially John Hughlings Jackson, showed that some seizures began in one restricted body region and spread in an orderly sequence.
A seizure might begin in one thumb, hand or side of the face before progressing.
Such an attack was not simply a ‘small’ seizure.
Its importance lay in where it began.
Jackson’s work helped demonstrate that seizure onset could contain anatomical information and that a focal seizure could later spread into a bilateral convulsion.
This immediately weakened any classification based only on whether the final event looked grand or petit.
A large convulsion could have a focal beginning
This was one of the decisive conceptual problems with the term grand mal.
Two people might both end with bilateral tonic-clonic movements.
One seizure might have been generalised from the beginning.
The other might have started focally and spread.
If both were simply labelled grand mal, an important biological difference disappeared.
Later EEG and surgical work would make that distinction even more important.
‘Petit mal’ had the opposite problem
The category of petit mal grouped together events that looked minor but were not necessarily the same seizure type.
Typical absence seizures could be brief and subtle.
So could focal impaired-consciousness seizures.
Some focal motor seizures involved only a small body region.
Other brief paroxysmal events were not epileptic at all.
A term based mainly on apparent mildness therefore risked combining disorders with very different mechanisms.
EEG changes the basis of classification
The development of human EEG in the 1920s and 1930s changed seizure classification fundamentally.
Researchers could now compare what a seizure looked like with what the brain’s electrical activity showed.
The classic approximately 3-Hz generalised spike-and-wave pattern associated with typical absence attacks looked very different from focal interictal spikes or focal ictal activity.
Suddenly, seizures that had once been grouped by appearance could be separated by electroclinical pattern.
Classification began moving from ‘large versus small’ toward ‘where and how does the seizure begin?’
The focal–generalised distinction emerges
By the mid-twentieth century, one of the most important divisions in epilepsy was between focal and generalised seizure disorders.
Focal seizures were understood as arising from a limited region or network.
Generalised seizures appeared to involve both hemispheres rapidly and bilaterally.
The distinction was not perfect, and later network models would complicate it, but it was far more informative than grand mal versus petit mal.
It linked seizure description with EEG, anatomy and, increasingly, treatment decisions.
Classification becomes an international project
As epilepsy research expanded internationally, terminology became a practical problem.
Different countries and specialists used different names for similar events. The same term could mean different things in different publications.
The International League Against Epilepsy began developing formal classifications to create a shared language.
The modern history of official seizure classification therefore belongs not to one physician but to a sequence of international commissions, debates and revisions.
The 1960s: moving toward standardisation
During the 1960s, the ILAE developed formal seizure classification proposals.
The 1964 classification represented an early attempt to organise seizure types internationally using clinical and EEG information.
The goal was no longer merely to describe whether an event was major or minor.
Instead, classification increasingly considered the mode of seizure onset, clinical manifestations and electrophysiological features.
This period laid the groundwork for the more influential classifications that followed.
1970: the revised international seizure classification
A revised ILAE seizure classification appeared in 1970.
The system further established the distinction between seizures that began focally and those considered generalised from onset.
Older language still survived in everyday practice, but formal epileptology was moving decisively away from the grand-mal/petit-mal binary.
Classification had become an electroclinical exercise rather than a simple description of visible severity.
1981: a classification that shaped decades of practice
The ILAE’s 1981 seizure classification became one of the most influential systems in modern epilepsy history.
It divided seizures broadly into partial seizures, generalised seizures and unclassified epileptic seizures.
‘Partial’ was the terminology then used for what would later be called focal seizures.
Partial seizures were further separated according to whether consciousness was impaired, using terms such as simple partial and complex partial.
Generalised seizures included absence, myoclonic, clonic, tonic, tonic-clonic and atonic types.
This system was far more precise than grand mal and petit mal, but it would eventually create terminology problems of its own.
‘Simple partial’ and ‘complex partial’
These terms became deeply embedded in late twentieth-century neurology.
A simple partial seizure generally referred to a focal seizure without impairment of consciousness.
A complex partial seizure involved altered consciousness.
The words were widely used, but they were not especially transparent outside specialist medicine.
‘Simple’ could imply that a seizure was clinically unimportant.
‘Complex’ did not clearly explain what was complex about it.
Later revisions would replace them with more descriptive terminology.
‘Secondarily generalised’ seizures
The 1981 framework also used the concept of a partial seizure becoming secondarily generalised.
This was an important advance over grand mal because it preserved the history of the seizure’s onset.
A bilateral tonic-clonic event that evolved from a focal seizure was no longer classified in exactly the same way as a seizure generalised from the beginning.
That distinction had direct relevance to diagnosis, imaging and possible epilepsy surgery.
1989: seizure type and epilepsy syndrome are not the same thing
The ILAE’s 1989 classification of epilepsies and epilepsy syndromes emphasised another crucial distinction.
A seizure type describes the event.
An epilepsy syndrome describes a broader clinical disorder defined by a combination of seizure types, age, EEG findings, prognosis and other features.
This separation meant that the same seizure type could occur in more than one epilepsy syndrome.
It also made it increasingly clear that older labels such as petit mal could not adequately represent the complexity of epilepsy diagnosis.
Idiopathic, symptomatic and cryptogenic
Late twentieth-century classifications also used aetiological categories such as idiopathic, symptomatic and cryptogenic.
These terms attempted to distinguish presumed genetic epilepsies from those caused by known structural or acquired disorders and those suspected to be symptomatic despite an unidentified cause.
As genetics and neuroimaging advanced, these categories also became increasingly unsatisfactory.
Later classifications would move toward terms such as genetic, structural, metabolic, immune, infectious and unknown.
The evolution shows that seizure classification and epilepsy-cause classification were changing in parallel.
Why the 1981 system eventually became inadequate
The 1981 seizure classification was extraordinarily influential, but medicine changed around it.
Video-EEG revealed complex seizure sequences.
MRI identified structural causes that had previously been invisible.
Genetics transformed understanding of generalised and developmental epilepsies.
Intracranial recordings showed that some seizures did not fit comfortably into old categories.
And terminology such as simple partial, complex partial and secondary generalisation became increasingly difficult to explain clearly to patients and non-specialists.
2010: terminology begins to shift
In 2010, the ILAE proposed revised terminology and concepts for organising seizures and epilepsies.
The word focal increasingly replaced partial.
The conceptual separation between focal and generalised epilepsy remained important, but the League acknowledged that the underlying biology was more complicated than a rigid two-box model.
The change was part of a broader move toward clearer language and away from terms whose historical meanings no longer matched contemporary understanding.
2017: a major operational revision
The 2017 ILAE operational classification was designed to make seizure terminology more transparent and usable.
The major onset groups were focal onset, generalised onset and unknown onset.
Focal seizures could be classified according to awareness and whether the first prominent feature was motor or nonmotor.
The old terms simple partial and complex partial were abandoned.
‘Secondarily generalised’ was replaced by focal to bilateral tonic-clonic seizure.
The terminology now tried to say directly what the seizure was doing rather than rely on inherited jargon.
Why ‘focal to bilateral tonic-clonic’ was an important change
This phrase preserves both beginning and evolution.
Focal says where the seizure starts.
To bilateral indicates spread.
Tonic-clonic describes the later motor pattern.
That is much more informative than calling the final convulsion grand mal.
The terminology itself carries part of the seizure history.
The category of unknown onset
The 2017 system also formally allowed clinicians to classify a seizure when the beginning had not been observed.
This is important in real life.
A person may be found convulsing without anyone seeing the first few seconds.
It is unsafe to assume the seizure was generalised from onset simply because the observed phase was bilateral.
The unknown-onset category therefore made uncertainty explicit rather than forcing a premature classification.
Classification of seizure is not classification of epilepsy
The 2017 ILAE framework also made clear that diagnosis operates at several levels.
First comes seizure type.
Then epilepsy type: focal, generalised, combined generalised and focal, or unknown.
Then, where possible, a specific epilepsy syndrome.
Aetiology is considered alongside these levels.
This layered framework is fundamentally different from the old idea that epilepsy could be divided simply into major and minor attacks.
2025: the classification changes again
In 2025, the ILAE updated the operational classification of epileptic seizures again.
The four main seizure classes are now Focal, Generalized, Unknown whether focal or generalized, and Unclassified.
The word onset was removed from the names of the four main classes.
Consciousness replaced awareness as a classifier for focal and unknown seizures, operationally incorporating both awareness and responsiveness.
The previous motor-versus-nonmotor distinction was replaced by the language of observable and non-observable manifestations.
And the chronological sequence of seizure manifestations was given greater emphasis.
Why chronological sequence matters
This change has an interesting historical echo.
Hughlings Jackson had already shown in the nineteenth century that the order of seizure symptoms could contain crucial localising information.
The 2025 classification again emphasises describing seizure manifestations in their chronological sequence rather than relying only on the first visible feature.
The modern framework is vastly more sophisticated, but the principle that seizure evolution matters has deep historical roots.
Why classifications keep changing
A classification is not a permanent statement of biological truth.
It is a working language.
It has to reflect current evidence, guide treatment, communicate risk and remain usable across different health systems and languages.
As the ILAE itself emphasises, classification changes as research, technology and clinical experience change.
That is why modern terminology should not be treated as the final chapter in the story.
Why grand mal became misleading
The term grand mal hides several questions.
Was the seizure focal at the start?
Was it generalised from the beginning?
Was onset unknown?
Was the event actually epileptic?
What syndrome does it belong to?
What does the EEG show?
A visually dramatic convulsion cannot answer these questions by itself.
Modern classification therefore uses tonic-clonic as a seizure description while preserving information about whether the seizure is focal, generalised or of uncertain origin.
Why petit mal became misleading
The term petit mal has the opposite problem.
It tells us that the event looked small.
It does not reliably tell us whether the event was a typical absence, atypical absence, focal impaired-consciousness seizure or another brief event.
Modern terminology therefore names the actual seizure type rather than placing it in a vague ‘minor’ category.
The detailed history of that change is explored on the site’s separate absence terminology page.
‘Big’ and ‘small’ were never enough
The old grand-mal/petit-mal system also carried an unintended judgement about importance.
A seizure that lasts only seconds can still occur dozens or hundreds of times, interfere with learning or work, and signal a specific epilepsy syndrome.
A dramatic tonic-clonic seizure may be the visible endpoint of a focal process that began much earlier.
Seizure significance therefore cannot be measured by spectacle.
Old terminology still appears in records
Historical medical notes, older research papers and some patients’ longstanding diagnoses may still use grand mal, petit mal, simple partial, complex partial or secondary generalisation.
Those terms should not simply be deleted from history.
They need to be translated carefully.
For example, ‘grand mal’ in an old record does not automatically establish whether the seizure was focal-to-bilateral or generalised from onset.
Likewise, ‘complex partial’ broadly overlaps with modern focal seizures involving impaired consciousness, but old case descriptions still need to be read individually.
Why classification matters beyond language
Classification affects more than terminology.
It can influence medication choice.
It can determine which EEG patterns are sought.
It can affect whether MRI or surgical evaluation is prioritised.
It shapes research inclusion criteria and epidemiological statistics.
And it helps clinicians communicate what is known — and what remains uncertain — about a person’s seizures.
A better name can therefore lead to better clinical questions.
The classification is operational, not perfect
The ILAE explicitly describes recent seizure classifications as operational.
That means they are practical systems designed for clinical use rather than claims that every seizure fits a perfectly known biological category.
The 2017 paper acknowledged that existing knowledge was not sufficient for a wholly scientific classification based only on mechanisms.
The 2025 revision continues that pragmatic approach while incorporating evidence and experience from using the previous framework.
The central historical lesson
The move from grand mal and petit mal to modern seizure classification was not merely a vocabulary update.
It reflected a profound change in what physicians thought mattered.
First, seizures were grouped by how dramatic they looked.
Then focal onset became important.
EEG added electrical patterns.
Syndrome classification separated the seizure from the wider epilepsy disorder.
Imaging, genetics and video-EEG revealed further complexity.
International classifications gradually replaced inherited labels with terms that describe origin, consciousness, manifestations and evolution more precisely.
The old question was: Is this a big seizure or a small one?
The modern question is much richer: What kind of seizure is this, where does it begin, how does it evolve, and what epilepsy does it belong to?
Sources and further reading
Chang RSK et al. Classifications of seizures and epilepsies, where are we? A brief historical review and update. Journal of the Formosan Medical Association. 2017.
Fisher RS et al. Operational classification of seizure types by the International League Against Epilepsy. Epilepsia. 2017.
International League Against Epilepsy. Operational Classification of Seizure Types. 2017.
International League Against Epilepsy. Classification of the Epilepsies. 2017.
ILAE Commission on Classification and Terminology — archive and historical classification documents.
International League Against Epilepsy. Updated classification of epileptic seizures. 2025.
Beniczky S et al. Updated classification of epileptic seizures: Position paper of the International League Against Epilepsy. Epilepsia. 2025.
Varnado S, Price D. Basics of modern epilepsy classification and terminology. Current Problems in Pediatric and Adolescent Health Care. 2020.
Historical evidence checked: September 2026.