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A definition and classification of status epilepticus –Report
of the ILAE Task Force on Classification of Status
Epilepticus
*†‡Eugen Trinka, §Hannah Cock, ¶Dale Hesdorffer, #Andrea O. Rossetti, **Ingrid E. Scheffer,
††Shlomo Shinnar, ‡‡Simon Shorvon, and §§Daniel H. Lowenstein
Epilepsia, **(*):1–9, 2015
doi: 10.1111/epi.13121
Eugen Trinka is
professor and
chairman of
Department of
Neurology, Paracelsus
Medical University
Salzburg Austria.
SUMMARY
The Commission on Classification and Terminology and the Commission on Epidemiology
of the International League Against Epilepsy (ILAE) have charged a Task Force to revise
concepts, definition, and classification of status epilepticus (SE). The proposed new defini-
tion of SE is as follows: Status epilepticus is a condition resulting either from the failure of the
mechanisms responsible for seizure termination or from the initiation of mechanisms, which lead
to abnormally, prolonged seizures (after time point t
1
). It is a condition, which can have long-term
consequences (after time point t
2
), including neuronal death, neuronal injury, and alteration of
neuronal networks, depending on the type and duration of seizures. This definition is concep-
tual, with two operational dimensions: the first is the length of the seizure and the time
point (t
1
) beyond which the seizure should be regarded as “continuous seizure activity.”
The second time point (t
2
) is the time of ongoing seizure activity after which there is a risk
of long-term consequences. In the case of convulsive (tonic–clonic) SE, both time points (t
1
at 5 min and t
2
at 30 min) are based on animal experiments and clinical research. This evi-
dence is incomplete, and there is furthermore considerable variation, so these time points
should be considered as the best estimates currently available. Data are not yet available
for other forms of SE, but as knowledge and understanding increase, time points can be
defined for specific forms of SE based on scientific evidence and incorporated into the defi-
nition, without changing the underlying concepts. A new diagnostic classification system of SE
is proposed, which will provide a framework for clinical diagnosis, investigation, and thera-
peutic approaches for each patient. There are four axes: (1) semiology; (2) etiology; (3) elec-
troencephalography (EEG) correlates; and (4) age. Axis 1 (semiology) lists different forms
of SE divided into those with prominent motor systems, those without prominent motor
systems, and currently indeterminate conditions (such as acute confusional states with
epileptiform EEG patterns). Axis 2 (etiology) is divided into subcategories of known and
unknown causes. Axis 3 (EEG correlates) adopts the latest recommendations by consensus
panels to use the following descriptors for the EEG: name of pattern, morphology, location,
time-related features, modulation, and effect of intervention. Finally, axis 4 divides age
groups into neonatal, infancy, childhood, adolescent and adulthood, and elderly.
KEY WORDS: Status epilepticus, Seizure, Definition, Classification, Seizure duration.
Accepted July 15, 2015.
*Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; †Center for Cognitive Neuroscience,
Salzburg, Austria; ‡Department of Public Health Technology Assessment, UMIT –University for Health Sciences, Medical Informatics and Technology,
Hall.i.T., Austria; §Institute of Medical & Biomedical Education, Epilepsy Group, Atkinson Morley Regional Neuroscience Centre, St. Georges
University Hospitals NHS Foundation Trust, St George’s University of London, London, United Kingdom; ¶GH Sergievsky Center and Department of
Epidemiology, Columbia University, New York, New York, U.S.A.; #Department of Clinical Neurosciences, CHUV and University of Lausanne,
Lausanne, Switzerland; **Florey Institute of Neuroscience and Mental Health, Austin Health and Royal Children’s Hospital, University of Melbourne,
Melbourne, Victoria, Australia; ††Departments of Neurology, Pediatrics, and Epidemiology and Population Health Montefiore Medical Center, Albert
Einstein College of Medicine, Bronx, New York, U.S.A.; ‡‡National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London,
United Kingdom; and §§Department of Neurology, University of California, San Francisco, California, U.S.A.
Address correspondence to Eugen Trinka, Department of Neurology, Christian Doppler Klinik, Centre for Cognitive Neuroscience Salzburg, Paracelsus
Medical University Salzburg, Ignaz Harrerstrasse 79, A-5020 Salzburg, Austria. E-mail: e.trinka@salk.at
Wiley Periodicals, Inc.
©2015 International League Against Epilepsy
1
SPECIAL REPORT
Key Points
•A new conceptual definition of status epilepticus with
two operational dimensions (t
1
and t
2
) is proposed
•Time point t
1
indicates when treatment should be initi-
ated, and time point t
2
indicates when long-term con-
sequences may appear
•The Task Force also proposes a new classification of
SE that will provide a framework for clinical diagnosis
and therapeutic approaches for each patient
Trousseau, 1867: “In the status epilepticus, when the
convulsive condition is almost continuous, something
special takes place which requires an explanation.”
Comment: Historical
Introduction
Status epilepticus (SE), considered the most extreme
form of a seizure, was included in the classification of
seizures of the International League Against Epilepsy
(ILAE) of 1970
1
and 1981.
2
In the first ILAE Classifica-
tion of Seizures, which was developed in 1964 and
approved in 1970,
1
SE was defined in the addendum of
the publication as a “seizure that persists for a sufficient
length of time or is repeated frequently enough to pro-
duce a fixed and enduring condition.”SE was divided
into partial, generalized, or unilateral types, and basically
mirrored the seizure classification.
1,3
In the revision of
1981, the definition was minimally changed into a “sei-
zure”that “persists for a sufficient length of time or is
repeated frequently enough that recovery between attacks
does not occur.”
2
Again, the distinction between partial,
generalized, and epilepsia partialis continua (EPC) was
mentioned in the addendum of the Classification, without
further details.
2
These concepts, although highly valu-
able, were imprecise, as they did not define the duration
of a seizure that was “fixed and enduring”or “sufficient
length,”nor was there a clinical description (semiology)
of the type of SE in the Classification of 1970 and its
1981 revision. These issues were not resolved with the
report of the Core Group on Classification.
4
The ILAE recognized the need to revise the Classifica-
tion of SE and the Chairs of the Commission of Classifi-
cation and Terminology (Ingrid Scheffer) and the
Commission on Epidemiology (Dale Hesdorffer and
Ettore Beghi). Ingrid Scheffer (Australia), Ding Ding
(China), Ed Dudek (U.S.A.), Daniel Lowenstein
(U.S.A.), Hannah Cock (United Kingdom), Dale
Hesdorffer (U.S.A.), Andrea Rossetti (Switzerland),
Shlomo Shinnar (U.S.A.), Simon Shorvon (United
Kingdom), and Eugen Trinka (Austria).
Purpose of Classification
Classification refers to the way in which items are orga-
nized and should be ideally based on the underlying neuro-
biology to form natural classes or entities.
5
Because current
knowledge regarding the pathophysiology and the underly-
ing neurobiology of status epilepticus is far from complete,
a proposed classification can be only a compromise between
a conceptual, scientific (drawing on what is known) and
pragmatic empirical classification.
6
A classification has to serve several purposes. First, it has
to facilitate communication between clinicians by providing
them with a common language. The classes should be clini-
cally differentiated. Second, classification should help to
improve the treatment of patients, based on current under-
standing of pathophysiology, prognosis, etiology, and age.
Third, classification should permit the conduct of epidemio-
logic studies of consequences and prevention. Fourth, clas-
sification should guide basic research to identify natural
classes (i.e., entities or diseases sensu strictu), which in turn
will form the basis of a true scientific classification in the
future. Therefore, it is important to emphasize that the pro-
posed classification is merely a framework and must not be
treated as a doctrine, but reflect our current knowledge on
status epilepticus. Future advances in basic, epidemiologic,
and clinical research will undoubtedly lead to modifications
and major revisions of this proposed classification of SE.
A classification of SE cannot simply reflect the classifica-
tion of seizure types, since symptoms and signs during the
fixed stage of SE frequently are different compared to
symptoms during short-lasting seizures. At least half of the
patients presenting with SE do not have epilepsy, and acute
neurologic disorders and the long duration of status leads to
significant variability in its clinical presentation (i.e., semi-
ology). SE is not a disease entity but rather a symptom with
a myriad of etiologies.
Definition of Status Epilepticus
A seizure is defined as “a transient occurrence of signs
and/or symptoms due to abnormal excessive or synchronous
neuronal activity in the brain. The term transient is used as
demarcated in time, with a clear start and finish.”Classi-
cally SE was defined as a “a condition characterized by an
epileptic seizure that is sufficiently prolonged or repeated at
sufficiently brief intervals so as to produce an unvarying
and enduring epileptic condition.”
7,8
Because the ILAE definitions of SE have not provided a
precise definition of the duration of SE,
1–5
different opera-
Epilepsia, **(*):1–9, 2015
doi: 10.1111/epi.13121
2
E. Trinka et al.
tional definitions have been provided in textbooks, research
papers, and clinical trials. The seminal work by Meldrum
et al.
9
suggested that 82 min or longer of ongoing seizure
activity in baboons can cause irreversible neuronal injury due
to excitotoxicity. This observation led to the commonly used
definition for SE as seizure duration of 30 min.
10,11
The ratio-
nale behind this definition was that irreversible neuronal
injury may occur after 30 min of ongoing seizure activity.
This definition, therefore, remains useful for epidemiologic
studies focused on consequences and prevention of SE. Clini-
cians have rightfully argued for the need to start treatment
earlier, because the prognosis of SE worsens with increasing
duration.
12,13
Several suggestions of a shorter timeframe for
SE have subsequently been made, but none has been based on
scientific evidence provided by prospective studies.
This problem was addressed in an article by Lowenstein
et al.
14
The obvious discrepancy between the limited
knowledge of the pathophysiology and the need to treat
patients rapidly led to the concept of an operational and a
conceptual definition. Generalized convulsive SE in adults
and children older than 5 years was operationally defined as
“...≥5 min of (1) continuous seizure or (2) two or more dis-
crete seizures between which there is incomplete recovery
of consciousness,”
14
This time frame has been generally
accepted by the clinical community and used to guide when
emergency treatment of generalized convulsive SE should
commence. As a basic research (or conceptual) definition,
the ILAE Core Group on Classification group suggested the
following: “Generalized, convulsive status epilepticus
refers to a condition in which there is failure of the “nor-
mal”factors that serve to terminate a typical GTCS [gener-
alized tonic–clonic seizures].”
15
Although this distinction
between a pragmatic, operational definition and a basic
research definition of generalized convulsive status has
guided the treatment of generalized convulsive SE, other
forms of SE have not been addressed.
The ILAE Task Force on Classification of Status Epilep-
ticus proposes a definition that encompasses all types of SE,
and takes into consideration current knowledge regarding
the pathophysiology of SE and the need to address clinical
treatment decision making time points, as well as the con-
duct of epidemiologic and clinical studies:
SE is a condition resulting either from the failure of the
mechanisms responsible for seizure termination or from
the initiation of mechanisms which lead to abnormally
prolonged seizures (after time point t
1
). It is a condition
that can have long-term consequences (after time point
t
2
), including neuronal death, neuronal injury, and alter-
ation of neuronal networks, depending on the type and
duration of seizures.
This definition is conceptual, with two operational
dimensions: the first is the length of the seizure and the
time point (t
1
) at which the seizure should be regarded as
an “abnormally prolonged seizure.”The second time
point (t
2
) is the time of ongoing seizure activity beyond
which there is a risk of long-term consequences. In the
case of convulsive (tonic–clonic) SE, both time points are
based on animal experiments and clinical research. This
evidence is incomplete; there is furthermore considerable
variation, so these time points should be considered as
the best estimates currently available. Data are not yet
available for other forms of SE, but as knowledge and
understanding increases, time points can be defined for
specific forms of SE based on scientific evidence and
incorporated into the definition, without changing the
underlying concepts. This division into two time points
has clear clinical implications: The time point of opera-
tional dimension 1 determines the time at which treatment
should be considered or started, whereas the time point of
operational dimension 2 determines how aggressively
treatment should be implemented to prevent long-term
consequences. The time domain may vary considerably
between different forms of SE.
Data from select populations with refractory epilepsy
undergoing video–electroencephalography (EEG) monitor-
ing indicate that most convulsive seizures last <5 min.
16–20
In unselected community-based populations, the data sug-
gest that the estimated duration of seizures >5 min is much
more common than suggested by inpatient monitoring and
that ≥10% of first unprovoked seizures last longer than
30 min.
20,21
Observations from a less selected pediatric
population show that there are two subgroups of patients,
one with a tendency to brief seizures (<5 min) and the other
subgroup that represents a significant minority of patients
with a propensity to more prolonged seizures.
20
In this
study, a seizure that lasted >7 min was likely to be pro-
longed and therefore required acute treatment. Taken
together, these findings led the Task Force to reach a con-
sensus opinion that treatment of convulsive seizures should
be initiated at around 5 min.
Given the experimental evidence indicating irreversible
brain damage after prolonged seizures
9
and the potential
threat of brain damage in humans, we suggest the time of
t
2
at 30 min in convulsive SE, in line with previous defi-
nitions of SE.
10,11
As in the animal experimentation, con-
siderable variation in the duration of prolonged seizures
that result in damage has been found, but this time point
is chosen on the basis of providing a practical safe guide-
line for clinical purposes. There is limited information to
define t
1
and t
2
in focal SE,
19, 22
and no information for
absence SE (see Table 1). Furthermore, the likelihood of
damage is dependent on the location of the epileptic focus
(also true in experimental animals), the intensity of the
status, the age of the patient, and other factors, and
research is needed to define these aspects further. It must
be emphasized that the time limits given in Table 1 are
meant primarily for operational purposes. They are
Epilepsia, **(*):1–9, 2015
doi: 10.1111/epi.13121
3
Definition and Classification of Status Epilepticus
general approximations only, and the timing of onset of
cerebral damage will vary considerably in different clini-
cal circumstances.
Comment: Axes
The purpose of the diagnostic axes is to provide a frame-
work for clinical diagnosis, investigation, and therapeu-
tic approaches for each patient.
1,4
Previously, in 1970,
the axes encompassed (1) clinical seizure type, (2) elec-
troencephalographic ictal and interictal expression, (3)
anatomic substrate, (4) etiology, and (5) age. In the 1981
revision, the axes were limited to the seizure type and
EEG expression (ictal and interictal) (Classification
1981).
At least half of the patients with SE do not have epilepsy
or specific epilepsy syndromes—they have SE due to
acute or remote central nervous system or systemic ill-
ness. Therefore, the axes used previously in seizure clas-
sification need to be modified for the classification of
status epilepticus.
Classification of Status
Epilepticus
For classification of SE we propose the following four
axes:
1Semiology
2Etiology
3EEG correlates
4Age
Ideally, every patient should be categorized according
to each of the four axes. However, it is acknowledged
that this will not always be possible. At initial presenta-
tion, the approximate age of the patient and the semiol-
ogy will be immediately assessable. The etiology will be
apparent less frequently and may take time to identify. It
is also recognized that EEG recordings will not be avail-
able in many settings, particularly at presentation. How-
ever, the EEG will affect choice and aggressiveness of
treatment, prognosis, and clinical approaches, so an EEG
should be sought where possible and as early as possible.
In fact, some forms of SE may only be reliably diagnosed
by EEG.
23
Like in other acute neurologic conditions, the
semiology (symptoms and signs) and the EEG pattern in
SE are highly dynamic and may change over short time
periods in a given patient. Thus, repeated neurologic
examinations and EEG investigations in a patient with SE
may lead to a different classification. For example, SE
may start with focal motor symptoms evolving into bilat-
eral convulsive SE (A.1.b) and may present a few hours
later as nonconvulsive SE (NCSE) with coma and minor
motor phenomena resembling so called “subtle status”
(B.1). Likewise, the EEG may show lateralized periodic
discharges at the beginning and a bilateral synchronous
pattern at the second investigation.
Axis 1: Semiology
This axis refers to the clinical presentation of SE and is
therefore the backbone of this classification. The two main
taxonomic criteria are:
1. The presence or absence of prominent motor
symptoms
2The degree (qualitative or quantitative) of impaired con-
sciousness
Those forms with prominent motor symptoms and
impairment of consciousness may be summarized as con-
vulsive SE as opposed to the nonconvulsive forms of SE
(NCSE). Although the term convulsion is sometimes disre-
garded as a lay term, it reflects the clinician0s ordinary lan-
guage. In fact “status epilepticus”is also a lay term, as it is
the English translation of
etat de mal, which was used in the
19th century by patients in the Salp^
etri
ere.
24
Thus, it was
decided to keep the well-accepted term “convulsive.”It des-
ignates “episodes of excessive abnormal muscle contrac-
tions, usually bilateral, which may be sustained, or
interrupted”
25
(Table 2).
Table 1. Operational dimensions with t
1
indicating the time that emergency treatment of SE should be started and t
2
indicating the time at which long-term consequences may be expected
Type of SE
Operational dimension 1
Time (t
1
), when a seizure is likely to
be prolonged leading to continuous
seizure activity
Operational dimension 2
Time (t
2
), when a seizure may
cause long term consequences
(including neuronal injury, neuronal death, alteration
of neuronal networks and functional deficits)
Tonic–clonic SE 5 min 30 min
Focal SE with impaired
consciousness
10 min >60 min
Absence status epilepticus 10–15 min
a
Unknown
a
Evidence for the time frame is currently limited and future data may lead to modifications.
Epilepsia, **(*):1–9, 2015
doi: 10.1111/epi.13121
4
E. Trinka et al.
Axis 2: Etiology
The underlying cause (etiology) of SE is categorized in a
manner that is consistent with the concepts of the ILAE
Commission for Classification proposal 2010,
5
but
acknowledges the well-established terms that are used by
epileptologists, emergency doctors, neurologists, pediatric
neurologists, neurosurgeons, family doctors, and other clini-
cians looking after patients with SE (Table 3).
The term “known”or “symptomatic”is used—consistent
with the common neurologic terminology—for SE caused
by a known disorder, which can be structural, metabolic,
inflammatory, infectious, toxic, or genetic. Based on its
temporal relationship, the subdivisions acute, remote, and
progressive can be applied.
The term “idiopathic”or “genetic”is not applicable to the
underlying etiology of SE. In idiopathic or genetic epilepsy
syndromes, the cause of status is not the same as for the dis-
ease, but some metabolic, toxic, or intrinsic factors (like
sleep deprivation) may trigger SE in these syndromes.
Therefore, the term “idiopathic”
28
or “genetic”
5
is not used
here. SE in a patient with juvenile myoclonic epilepsy
(which itself is “idiopathic”or “genetic”) can be symp-
tomatic, due to inappropriate antiepileptic drug (AED) treat-
ment, abrupt drug withdrawal, or drug intoxication.
The term “unknown”or “cryptogenic”(Greek: jqύpsοϛ,
hidden or unknown, s
ocέmοϛ, family, class, descent, origin)
is used in its strict original meaning: unknown cause. The
assumption that it is “presumably”symptomatic or genetic
is inappropriate. Synonymously and consistent with the pro-
posal 2010,
5
the term “unknown”or appropriate translations
in different languages can be used (Table 4).
SE in its varied forms has a plethora of causes; a list is
attached (Appendix 1). The list will be updated periodically
and will provide a database for clinicians.
Axis 3: Electroencephalographic correlates
None of the ictal EEG patterns of any type of SE is spe-
cific. Epileptiform discharges are regarded as the hallmark,
but with increasing duration of SE, the EEG changes and
rhythmic nonepileptiform patterns may prevail. Similar EEG
patterns, such as triphasic waves, can be recorded in various
pathologic conditions, leading to substantial confusion in the
literature. Although the EEG is overloaded with movement
and muscle artifact in the convulsive forms of SE and thus of
limited clinical value, it is indispensable in the diagnosis of
NCSE, as the clinical signs (if any) are often subtle and non-
specific.
23,29
Advances in electrophysiologic techniques may
provide us with increased capability to utilize EEG in the
emergency setting and allow better delineation of the highly
dynamic changes of EEG patterns in the near future.
Currently there are no evidence-based EEG criteria for
SE. Based on large descriptive series and consensus
panels,
26,27,30–32
we propose the following terminology to
describe EEG patterns in SE:
1Location: generalized (including bilateral synchronous
patterns), lateralized, bilateral independent, multifocal.
2Name of the pattern: Periodic discharges, rhythmic delta
activity or spike-and-wave/sharp-and-wave plus subtypes.
3Morphology: sharpness, number of phases (e.g., triphasic
morphology), absolute and relative amplitude, polarity.
Table 2. Axis 1: Classification of status epilepticus (SE)
(A) With prominent motor symptoms
A.1 Convulsive SE (CSE, synonym: tonic–clonic SE)
A.1.a. Generalized convulsive
A.1.b. Focal onset evolving into bilateral convulsive SE
A.1.c. Unknown whether focal or generalized
A.2 Myoclonic SE (prominent epileptic myoclonic jerks)
A.2.a. With coma
A.2.b. Without coma
A.3 Focal motor
A.3.a. Repeated focal motor seizures (Jacksonian)
A.3.b. Epilepsia partialis continua (EPC)
A.3.c. Adversive status
A.3.d. Oculoclonic status
A.3.e. Ictal paresis (i.e., focal inhibitory SE)
A.4 Tonic status
A.5 Hyperkinetic SE
(B) Without prominent motor symptoms (i.e., nonconvulsive SE, NCSE)
B.1 NCSE with coma (including so-called “subtle” SE)
B.2 NCSE without coma
B.2.a. Generalized
B.2.a.a Typical absence status
B.2.a.b Atypical absence status
B.2.a.c Myoclonic absence status
B.2.b. Focal
B.2.b.a Without impairment of consciousness (aura continua, with
autonomic, sensory, visual, olfactory, gustatory, emotional/
psychic/experiential, or auditory symptoms)
B.2.b.b Aphasic status
B.2.b.c With impaired consciousness
B.2.c Unknown whether focal or generalized
B.2.c.a Autonomic SE
Table 3. Currently indeterminate conditions
(or “boundary syndromes”)
Epileptic encephalopathies
Coma with non evolving epileptiform EEG pattern
a
Behavioral disturbance (e.g., psychosis) in patients with epilepsy
Acute confusional states, (e.g., delirium) with epileptiform EEG
patterns
a
Lateralized and generalized periodic discharges with monotonous appear-
ance are not considered as evolving EEG patterns.
26,27
Table 4. Etiology of status epilepticus
Known (i.e., symptomatic)
Acute (e.g., stroke, intoxication, malaria, encephalitis, etc.)
Remote (e.g., posttraumatic, postencephalitic, poststroke, etc.)
Progressive (e.g., brain tumor, Lafora’s disease and other PMEs,
dementias)
SE in defined electroclinical syndromes
Unknown (i.e., cryptogenic)
Epilepsia, **(*):1–9, 2015
doi: 10.1111/epi.13121
5
Definition and Classification of Status Epilepticus
4Time-related features: prevalence, frequency, duration,
daily pattern duration and index, onset (sudden vs. grad-
ual), and dynamics (evolving, fluctuating, or static).
5Modulation: stimulus-induced vs. spontaneous.
6Effect of intervention (medication) on EEG.
Axis 4: Age
1Neonatal (0 to 30 days).
2Infancy (1 month to 2 years).
3Childhood (> 2 to 12 years).
4Adolescence and adulthood (> 12 to 59 years).
5Elderly (≥60 years).
Examples of SE that occur in different age groups, are
listed in Table 5 and Figure 1. SE in neonates may be subtle
and difficult to recognize. Some forms of SE are seen as an
integral part of the electroclinical syndrome; others can
occur in patients within a certain electroclinical syndrome,
or when trigger factors or precipitating causes are present,
such as sleep deprivation, intoxication, or inappropriate
medication. Examples are phenytoin in some forms of pro-
gressive myoclonic epilepsies,
33
carbamazepine in juvenile
myoclonic epilepsy,
34,35
or absence epilepsies.
36
Acknowledgments
This report was written by experts selected by the International League
Against Epilepsy (ILAE) and was approved for publication by the ILAE.
Opinions expressed by the authors, however, do not necessarily represent
the policy or position of the ILAE. The Task Force on Classification of SE
met six times (American Epilepsy Society Meeting, San Antonio, U.S.A.,
2010, Commission on European Affairs Workshop on the Classification of
SE at the 3rd London-Innsbruck Colloquium on Acute seizures and Status
Epilepticus, Oxford, United Kingdom, 2011, American Epilepsy Society
Meeting, Baltimore, 2011, European Congress on Epileptology, London,
2012, American Epilepsy Society, San Diego, 2012, and International Epi-
lepsy Congress, Montreal 2013). All members of the Task Force discussed
in a respectful, constructive, and fruitful atmosphere the new definition and
classification. We have also received valuable input from several members
of the Commission on Epidemiology and want to thank Ettore Beghi, Ding
Ding, Ed Dudek, Charles Newton, and David Thurman (in alphabetical
order) for their comments.
Conflict of Interest
Dr. Trinka has received research funding from UCB Pharma, Biogen-
Idec, Red Bull, Merck, the European Union, FWF €
Osterreichischer Fond
zur Wissenschaftsf€
orderung, and Bundesministerium f€
ur Wissenschaft
und Forschung and has acted as a paid consultant to Eisai, Takeda, Ever
Neuropharma, Biogen Idec, Medtronics, Bial, and UCB and has received
speakers’honoraria from Bial, Eisai, GL Lannacher, GlaxoSmithKline,
Boehringer, Viropharma, Actavis, and UCB Pharma. He has no specific
conflicts relevant to this work. Dr. Cock has served as a paid consultant
for Special Products Ltd and Eisai Europe Ltd, and received support from
UCB pharma, GlaxoSmithKline, and Lupin pharmaceuticals. Details at
www.whopaysthisdoctor.org. She has no specific conflicts relevant to this
work. Dr. Hesdorffer serves on Advisory Boards for Upsher-Smith and
Acorda; is a consultant to Cyberonics, The Department of Rehabilitation
Medicine at Mount Sinai Medical Center, and the Comprehensive Epi-
lepsy Center at NYU Langone Medical Center; and is an Associate Editor
of Epilepsia. She has no specific conflicts relevant to this work. Dr. Ros-
setti received research support from UCB Pharma and Sage Pharmaceuti-
cals. He has no specific conflicts relevant to this work. Dr. Scheffer has no
specific conflicts relevant to this work. Dr. Shinnar has served as consul-
tant to Accorda, AstraZeneca, Questcor, and Upsher-Smith. He serves on
a Daqta Safety Monitoring Board for UCB pharma. He has no specific
conflicts relevant to this work. Dr. Shorvon has received research grants,
or speakers or consultancy fees from Eisai, Viropharma, Sage, and
Takeda. He has no specific conflicts relevant to this work. Dr. Lowenstein
has served in the past as a paid consultant for Upsher-Smith, and his cur-
rent work with the Human Epilepsy Project, a research project adminis-
tered through the Epilepsy Study Consortium, is supported by UCB
Pharma, Pfizer, Lundbeck, and Eisai, as well as various foundations. He
has no specific conflicts relevant to this work. We confirm that we have
read the Journal’s position on issues involved in ethical publication and
affirm that this report is consistent with those guideline.
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Table 5. SE in selected electroclinical syndromes
according to age
SE occurring in neonatal and infantile-onset epilepsy syndromes
Tonic status (e.g., in Ohtahara syndrome or West syndrome)
Myoclonic status in Dravet syndrome
Focal status
Febrile SE
SE occurring mainly in childhood and adolescence
Autonomic SE in early-onset benign childhood occipital
epilepsy (Panayiotopoulos syndrome)
NCSE in specific childhood epilepsy syndromes and etiologies
(e.g., Ring chromosome 20 and other karyotype abnormalities,
Angelman syndrome, epilepsy with myoclonic-atonic seizures,
other childhood myoclonic encephalopathies; see Appendices
1–3)
Tonic status in Lennox-Gastaut syndrome
Myoclonic status in progressive myoclonus epilepsies
Electrical status epilepticus in slow wave sleep (ESES)
Aphasic status in Landau-Kleffner syndrome
SE occurring mainly in adolescence and adulthood
Myoclonic status in juvenile myoclonic epilepsy
Absence status in juvenile absence epilepsy
Myoclonic status in Down syndrome
SE occurring mainly in the elderly
Myoclonic status in Alzheimer’s disease
Nonconvulsive status epilepticus in Creutzfeldt-Jakob disease
De novo (or relapsing) absence status of later life
These forms of SE may be encountered prevalently in some age groups, but
not exclusively.
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Appendix 1: List of Etiologies
That May Cause Status
Epilepticus (Not Exhaustive)
1Cerebrovascular diseases
a Ischemic stroke
b Intracerebral bleeding
c Subarachnoid bleeding
d Subdural hematoma
e Epidural hematoma
f Sinus venous thrombosis and cortical venous throm-
bosis
g Posterior reversible leukoencephalopathy syndrome
h Vascular dementia
2CNS infections
a Acute bacterial meningitis
b Chronic bacterial meningitis
c Acute viral encephalitis (including Japanese B
encephalitis, herpes simplex encephalitis, human
herpesvirus 6)
d Progressive multifocal leukoencephalopathy (PML)
e Cerebral toxoplasmosis
f Tuberculosis
g Neurocysticercosis
h Cerebral malaria
i Atypical bacterial infections
j HIV-related diseases
k Prion diseases (Creutzfeldt-Jakob disease, CJD)
l Protozoal infections
m Fungal diseases
n Subacute sclerosing panencephalitis
o Progressive Rubella encephalitis
3Neurodegenerative diseases
a Alzheimer’s disease
b Corticobasal degeneration
c Frontotemporal dementia
4Intracranial tumors
a Glial tumors
b Meningioma
c Metastases
d Lymphoma
e Meningeosis neoplastica
f Ependymoma
g Primitive neuroectodermal tumor (PNET)
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Definition and Classification of Status Epilepticus
5Cortical dysplasias
a Focal cortical dysplasia (FCD) II, tuberous sclerosis
complex (TSC), hemimegalencephaly, hemi-
hemimegalencephaly
b Ganglioglioma, gangliocytoma, dysembryoplastic
neuroepithelial tumor (DNET)
c Periventricular nodular heterotopia (PNH) and other
nodular heterotopias
d Subcortical band heterotopia spectrum
e Lissencephaly
f Familial and sporadic polymicrogyria
g Familial and sporadic schizencephaly
h Infratentorial malformations (e.g., dentate dysplasia,
mamillary dysplasia, etc.)
6Head trauma
a Closed head injury
b Open head injury
c Penetrating head injury
7Alcohol related
a Intoxication
b Alcohol withdrawal
c Late alcohol encephalopathy with seizures
d Wernicke encephalopathy
8Intoxication
a Drugs
b Neurotoxins
c Heavy metals
9Withdrawal of or low levels of antiepileptic drugs
10 Cerebral hypoxia or anoxia
11 Metabolic disturbances (e.g., electrolyte imbalances,
glucose imbalance, organ failure, acidosis, renal failure,
hepatic encephalopathy, radiation encephalopathy, etc.)
12 Autoimmune disorders causing SE
a Multiple sclerosis
b Paraneoplastic encephalitis
c Hashimoto’s encephalopathy
d Anti-NMDA (N-methyl-D-aspartate) receptor ence-
phalitis
e Anti–voltage–gated potassium channel receptor
encephalitis (including anti–leucine–rich glioma
inactivated 1 encephalitis)
f Anti-glutamic acid decarboxylase antibody associ-
ated encephalitis
g Anti–alpha–amino–3–hydroxy–5–methylisoxazole–
4–propionic acid receptor encephalitis
h Seronegative autoimmune encephalitis
i Rasmussen encephalitis
j Cerebral lupus (systemic lupus erythematosus)
k CREST (calcinosis, Raynaud phenomenon, esophageal
dysmotility, sclerodactyly, telangiectasia) syndrome
l Adult-onset Still’s disease
m Goodpasture syndrome
n Thrombotic thrombocytopenic purpura (Moschcow-
itz syndrome, Henoch Sch€
onlein purpura)
13 Mitochondrial diseases causing SE
a Alpers disease
b Mitochondrial encephalopathy, lactic acidosis, and
stroke-like episodes (MELAS)
c Leigh syndrome
d Myoclonic encephalopathy with ragged red fibers
(MERRF)
e Neuropathy, ataxia, and retinitis pigmentosa (NARP)
14 Chromosomal aberrations and genetic anomalies
a Ring chromosome 20
b Angelman syndrome
c Wolf-Hirshhorn syndrome
d Fragile X syndrome
e X-linked mental retardation syndrome
f Ring chromosome 17
g Rett syndrome
h Down syndrome (trisomy 21)
15 Neurocutaneous syndromes
a Sturge-Weber syndrome
16 Metabolic disorders
a Porphyria
b Menkes disease
c Wilson disease
d Adrenoleukodystrophy
e Alexander disease
f Cobalamin C/D deficiency
g Ornithine transcarbamylase deficiency
h Hyperprolinemia
i Maple syrup urine disease
j 3-Methylcrotonyl Coenzyme A carboxylase deficiency
k Lysinuric protein intolerance
l Hydroxyglutaric aciduria
m Metachromatic leukodystrophy
n Neuronal ceroid lipofuscinosis (types I, II, III,
including Kufs disease)
o Lafora disease
p Unverricht-Lundborg disease
q Sialidosis (type I and II)
r Morbus Gaucher
s Beta ureidopropionase deficiency
t 3-Hydroxyacyl Coenzyme A dehydrogenase deficiency
u Carnitine palmitoyltransferase deficiency
v Succinic semialdehyde dehydrogenase deficiency
17 Others
a Familial hemiplegic migraine
b Infantile onset spinocerebellar ataxia (SCA)
c Wrinkly skin syndrome
d Neurocutaneous melanomatosis
e Neuroserpin mutation
f Wolfram syndrome
g Autosomal recessive hyperekplexia
h Cockayne syndrome
i Cerebral autosomal dominant arteriopathy with sub-
cortical infarcts and leukoencephalopathy (CADASIL)
j Robinow syndrome
k Malignant hyperpyrexia
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l Juvenile Huntington’s disease (Westphal variant)
Appendix 2: List of Specific
Associations in Which SE Is an
Integral Part of the Syndrome,
theEntity,orIsaSymptomwith
Strong Clinical Implications
(List Is Incomplete and Will Be
Elaborated)
Absence status in Ring chromosome 20 syndrome.
Angelman syndrome.
Absence status epilepsy.
37
Appendix 3: Previous Definitions
and Classifications of Status
Epilepticus by ILAE-Affiliated
Groups
1Classification of Seizures 1970 (endorsed by the ILAE
general assembly):
a Definition of SE: “... a seizure persists for a suffi-
cient length of time or is repeated frequently enough to
produce a fixed and enduring epileptic condition
(“status”implies a fixed or enduring state).”
b Classification of SE: “Status may be divided into par-
tial (e.g., Jacksonian), or generalized (e.g., absence
status or tonic–clonic status), or unilateral (e.g., hemi-
clonic) types.”
2Classification of Seizures Revised 1981 (endorsed by the
ILAE general assembly):
a Definition: “... a seizure persists for a sufficient
length of time or is repeated frequently enough that
recovery between attacks does not occur.”
b Classification: “Status may be divided into partial
(e.g., Jacksonian), or generalized (e.g., absence status
or tonic–clonic status). When very localized motor
status occurs, it is referred to as epilepsia partialis
continua.”
3Glossary of descriptive terms 2001:
a Definition of status epilepticus: “A seizure that shows
no clinical signs of arresting after a duration encom-
passing the great majority of seizures of that type in
most patients or recurrent seizures without interictal
resumption of baseline central nervous system func-
tion.”
4Diagnostic scheme for people with epileptic seizures and
with epilepsy 2001:
a Classification: Continuous seizure types:
i Generalized status epilepticus
1 Generalized tonic–clonic status epilepticus
2 Clonic status epilepticus
3 Absence status epilepticus
4 Tonic status epilepticus
5 Myoclonic status epilepticus
ii Focal status epilepticus
1 Epilepsia partialis continua (EPC) of Kojevnikov
2 Aura continua
3 Limbic status epilepticus (psychomotor status)
4 Hemiconvulsive status epilepticus with hemiparesis
5Definition of epileptic seizures and epilepsy 2005:
a Definition of seizure: “An epileptic seizure is a tran-
sient occurrence of signs and/or symptoms due to
abnormal excessive or synchronous neuronal activity
in the brain. The term transient is used as demarcated
in time, with a clear start and finish.”
b Definition of status epilepticus: Though there is no
formal definition in the Report, SE is defined as “a
special circumstance with prolonged or recurrent
seizures.”
6Report of the ILAE Classification Core Group 2006:
a Definition: There is no formal definition of SE in the
2006 report, instead SE is described as “the failure of
natural homeostatic seizure-suppressing mechanisms
responsible for seizure termination ... . Regardless of
the specific operationalized definition, however, the
mechanisms involved in initiation and spread of the
various types of status epilepticus are, in general, sim-
ilar to those of self limited ictal events, but additional
factors that need to be considered in determining cri-
teria for classification include:
•Different mechanisms that can prevent seizure ter-
mination, for example, mechanisms that prevent
active inhibition, desynchronization of hypersyn-
chronous discharges, and depolarization block.
•Progressive features that contribute to subsequent
functional and structural brain disturbances.
•Maturational factors”
b Classification: The proposal of the core group recog-
nizes nine types of SE
i Epilepsia partialis continua (EPC) of Kojevnikov
ii Supplementary motor area (SMA) status epilepticus
iii Aura continua
iv Dyscognitive focal (psychomotor, complex partial)
status epilepticus
v Tonic–clonic status epilepticus
vi Absence status epilepticus
vii Myoclonic status epilepticus
viii Tonic status epilepticus
ix Subtle status epilepticus
Epilepsia, **(*):1–9, 2015
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Definition and Classification of Status Epilepticus
