Summary The International League Against Epilepsy (ILAE) presents a revised operational classification of seizure types. The purpose of such a revision is to recognize that some seizure types can have either a focal or generalized onset, to allow classification when the onset is unobserved, to include some missing seizure types, and to adopt more transparent names. Because current knowledge is insufficient to form a scientifically based classification, the 2017 Classification is operational (practical) and based on the 1981 Classification, extended in 2010. Changes include the following: (1) “partial” becomes “focal”; (2) awareness is used as a classifier of focal seizures; (3) the terms dyscognitive, simple partial, complex partial, psychic, and secondarily generalized are eliminated; (4) new focal seizure types include automatisms, behavior arrest, hyperkinetic, autonomic, cognitive, and emotional; (5) atonic, clonic, epileptic spasms, myoclonic, and tonic seizures can be of either focal or generalized onset; (6) focal to bilateral tonic–clonic seizure replaces secondarily generalized seizure; (7) new generalized seizure types are absence with eyelid myoclonia, myoclonic absence, myoclonic–atonic, myoclonic–tonic–clonic; and (8) seizures of unknown onset may have features that can still be classified. The new classification does not represent a fundamental change, but allows greater flexibility and transparency in naming seizure types.

Summary This companion paper to the introduction of the International League Against Epilepsy (ILAE) 2017 classification of seizure types provides guidance on how to employ the classification. Illustration of the classification is enacted by tables, a glossary of relevant terms, mapping of old to new terms, suggested abbreviations, and examples. Basic and extended versions of the classification are available, depending on the desired degree of detail. Key signs and symptoms of seizures (semiology) are used as a basis for categories of seizures that are focal or generalized from onset or with unknown onset. Any focal seizure can further be optionally characterized by whether awareness is retained or impaired. Impaired awareness during any segment of the seizure renders it a focal impaired awareness seizure. Focal seizures are further optionally characterized by motor onset signs and symptoms: atonic, automatisms, clonic, epileptic spasms, or hyperkinetic, myoclonic, or tonic activity. Nonmotor‐onset seizures can manifest as autonomic, behavior arrest, cognitive, emotional, or sensory dysfunction. The earliest prominent manifestation defines the seizure type, which might then progress to other signs and symptoms. Focal seizures can become bilateral tonic–clonic. Generalized seizures engage bilateral networks from onset. Generalized motor seizure characteristics comprise atonic, clonic, epileptic spasms, myoclonic, myoclonic–atonic, myoclonic–tonic–clonic, tonic, or tonic–clonic. Nonmotor (absence) seizures are typical or atypical, or seizures that present prominent myoclonic activity or eyelid myoclonia. Seizures of unknown onset may have features that can still be classified as motor, nonmotor, tonic–clonic, epileptic spasms, or behavior arrest. This “users’ manual” for the ILAE 2017 seizure classification will assist the adoption of the new system.

AIM We report four cases of acquired severe encephalopathy with massive hyperkinesia, marked neurological and cognitive regression, sleep disturbance, prolonged mutism, and a remarkably delayed recovery (time to full recovery between 5 and 18mo) with an overall good outcome, and its association with anti-N-methyl-D-aspartate (anti-NMDA) receptor antibodies.METHOD We reviewed the four cases retrospectively and we also reviewed the literature. RESULTS Anti-NMDA receptor antibodies (without ovarian teratoma detected so far) were found in the two children tested in this study. INTERPRETATIONThe clinical features are similar to those first reported in 1992 by Sebire et al., 1 and rarely recognized since. Sleep disturbance was not emphasized as part of the disorder, but appears to be an important feature, whereas coma is less certain and difficult to evaluate in this setting. The combination of symptoms, evolution (mainly seizures at onset), severity, paucity of abnormal laboratory findings, very slow recovery, and difficult management justify its recognition as a specific entity. The neuropathological substrate may be anatomically close to that involved in encephalitis lethargica, in which the same target functions (sleep and movement) are affected but in reverse, with hypersomnolence and bradykinesia. This syndrome closely resembles anti-NMDA receptor encephalitis, which has been reported in adults and is often paraneoplastic.In 1992, Sebire et al.1 reported a series of six children presenting with a novel combination of intense dyskinesia and severe regression with prolonged cognitive impairment but who made an unexpected excellent recovery.1 Since then, similar cases have been described. The disorder is sometimes called Sebire syndrome and is considered inflammatory or infectious in aetiology.2-5 Hartley et al., 6 in a paper entitled 'Immune-mediated chorea encephalopathy syndrome in childhood', specifically commented on the marked similarity between their cases and those of Sebire et al. Sleep disturbances (hypersomnolence) and dyskinesia (parkinsonism) are hallmarks of encephalitis lethargica, a condition increasingly recognized in children and presumed to be of autoimmune aetiology. In some cases, phases of insomnia and hyperkinesia, as in Sebire syndrome, may occur, suggesting that the localization of the acquired brain dysfunction may be in closely related areas and that common pathogenetic mechanisms are involved. This clinical picture is similar to the recently recognized entity, anti-N-methyl-D-aspartate (anti-NMDA) receptor encephalitis, 7 which may be the underlying cause of the disorder reported by Sebire et al.We describe four new cases of Sebire syndrome, in which sleeplessness was a highly significant clinical feature 'masked' by severe dyskinesia and agitation, persisting long after dyskinesia had resolved. Anti-NMDA receptor antibodies were found in the two individuals who were tested. Their serum was analysed at the Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK (P...

Dravet syndrome, a severe infantile epilepsy syndrome, is typically resistant to anti‐epileptic drugs (AED). Lamotrigine (LTG), an AED that is effective for both focal and generalized seizures, has been reported to aggravate seizures in Dravet syndrome. Therefore, LTG is usually avoided in Dravet syndrome. We describe two adults and a child with Dravet syndrome in whom LTG resulted in decreased seizure duration and frequency. This benefit was highlighted in each patient when LTG was withdrawn after 6 to 15 years, and resulted in an increased frequency of convulsive seizures together with longer seizure duration. A 25‐year‐old male required hospital admission for frequent seizures for the first time in 7 years, 6 weeks after ceasing LTG. Reintroduction of LTG improved seizure control, suggesting that in some patients with Dravet syndrome, LTG may be beneficial.

The last 2 years have seen exciting advances in the genetics of Landau-Kleffner syndrome and related disorders, encompassed within the epilepsy-aphasia spectrum (EAS). The striking finding of mutations in the N-methyl-D-aspartate (NMDA) receptor subunit gene GRIN2A as the first monogenic cause in up to 20% of patients with EAS suggests that excitatory glutamate receptors play a key role in these disorders. Patients with GRIN2A mutations have a recognizable speech and language phenotype that may assist with diagnosis. Other molecules involved in RNA binding and cell adhesion have been implicated in EAS; copy number variations are also found. The emerging picture highlights the overlap between the genetic determinants of EAS with speech and language disorders, intellectual disability, autism spectrum disorders and more complex developmental phenotypes.