Epilepsy syndromes in children

INTRODUCTION — The International League Against Epilepsy (ILAE) classification system is used by most epileptologists to categorize seizure types and epilepsy syndromes. This classification system has been revised since its origination in 1981 [1,2], most recently in 2022 [3-5]. (See "ILAE classification of seizures and epilepsy".)

The ILAE recognizes over 20 epilepsy syndromes, each defined by a distinctive combination of clinical features, signs and symptoms, and electrographic patterns; many of these syndromes begin in childhood (table 1). Epilepsy syndrome classification provides invaluable prognostic, therapeutic, and in the case of familial epilepsies, genetic information [6]. That being said, as an increasing number of genetic mutations have been identified in patients with both inherited and seemingly sporadic epilepsy syndromes, it has become clear that the phenotypic spectrum of various syndromes may be broader than what has been traditionally recognized, and the classification systems will continue to evolve.

This topic will review the clinical features, diagnosis, and treatment of some of the more common epilepsy syndromes that begin in infancy and childhood. Neonatal seizures and neonatal epilepsy syndromes are discussed separately. (See "Clinical features, evaluation, and diagnosis of neonatal seizures" and "Etiology and prognosis of neonatal seizures" and "Overview of neonatal epilepsy syndromes" and "Treatment of neonatal seizures".)

Additional topics relevant to the clinical features and diagnosis of seizures and epilepsy in children include the following:

● Seizures and epilepsy in children: Classification, etiology, and clinical features

● Seizures and epilepsy in children: Clinical and laboratory diagnosis

● Self-limited focal epilepsies of childhood

LENNOX-GASTAUT SYNDROME — The Lennox-Gastaut syndrome (LGS) is a lifelong, severe developmental epileptic encephalopathy associated with the onset of seizures in childhood, treatment-resistant epilepsy, and intellectual disability. Children usually present in the first seven years of life with a syndrome characterized by multiple seizure types, particularly tonic and atonic seizures; an atypical, slow spike-wave pattern on electroencephalogram (EEG); and intellectual disability, often with behavioral impairments.

LGS is reviewed in detail elsewhere. (See "Lennox-Gastaut syndrome".)

DEVELOPMENTAL AND EPILEPTIC ENCEPHALOPATHY WITH SPIKE-WAVE ACTIVATION IN SLEEP (DEE-SWAS)

Terminology and etiology — Syndromes associated with continuous or near-continuous spike-and-wave activity during sleep are now termed developmental and epileptic encephalopathy with spike-wave activation in sleep (DEE-SWAS), which encompasses the previously named syndromes of epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS) and Landau-Kleffner syndrome (LKS). Two key characteristics define this population of patients: marked sleep potentiation of epileptiform activity in the transition from wakefulness to sleep that leads to an EEG pattern of continuous or near-continuous spikes and waves during non-rapid eye movement (REM) sleep, and a regression in different aspects of development [7].

Although terminology has not been applied consistently, LKS referred to the epileptic encephalopathy associated with predominant language regression, continuous spike-wave activation in sleep (CSWS) referred to the more severe epilepsy syndrome associated with global developmental regression, and electrical status epilepticus during sleep (ESES) referred to the EEG pattern of continuous or near-continuous spike-and-wave during sleep that can be associated with a variety of clinical presentations. Self-limited epilepsy with centrotemporal spikes (SeLECTS), formerly known as benign epilepsy with centrotemporal spikes (BECTS) or benign rolandic epilepsy of childhood, is considered by many to lie on the most benign end of this spectrum and is discussed separately. (See "Self-limited focal epilepsies of childhood", section on 'Self-limited epilepsy with centrotemporal spikes (SeLECTS)'.)

The underlying etiology of disorders in this spectrum is unknown in most cases, although genetic causes may be increasingly recognized in both sporadic and familial cases. As an example, mutations in GRIN2A, a gene that encodes the alpha-2 subunit of the N-methyl-D-aspartate (NMDA)-selective glutamate receptor, were identified in 10 families with a spectrum of clinical phenotypes ranging from atypical rolandic epilepsy to LKS and CSWS, and in an additional eight subjects without a family history [8]. In other series, GRIN2A mutations were identified in 12 of 245 individuals (5 percent) with BECTS, 9 of 51 individuals (18 percent) with CSWS, and 4 of 44 cases (9 percent) of epilepsy-aphasia syndromes ranging from SeLECTS to CSWS [9,10]. Affected patients have a distinct speech phenotype, with prominent dysarthria and dyspraxia, which may have a lifelong impact on speech intelligibility [11].

In addition, early developmental lesions such as cortical malformations (eg, polymicrogyria) or vascular insults have been described in 40 to 60 percent of patients with CSWS but are rare in LKS [12-15].

Landau-Kleffner syndrome — LKS, now encompassed by the term DEE-SWAS, represents one of the best examples of deterioration of higher cortical functioning, in this case language, solely on the basis of frequent epileptiform activity.

Children with LKS develop normally until approximately three to six years of age, when they begin to lose language function. This later age of onset is in contrast with that of children with autism. The disorder begins with an auditory verbal agnosia; the children behave as if they are deaf. They ultimately have difficulties with expressive language and many have personality disorders and hyperkinetic behavior. They do not develop the striking behaviors associated with autism spectrum disorders, and usually they do not manifest a decline of overall cognitive function. (See 'Relationship with autism' below.)

Approximately 75 percent of children with LKS have clinical seizures, but these are rarely severe. The EEG abnormalities are quite dramatic and are required to make the diagnosis. The typical findings are bilateral centrotemporal spikes and sharp waves with fields that spread widely throughout both hemispheres. The diffuse spread of this bihemispheric focal activity often leads to the appearance of "generalized spike and wave" discharges. When the child falls asleep, the epileptiform activity becomes virtually continuous and is classified as ESES. To be considered ESES, more than 85 percent of non-REM sleep should be occupied by continuous epileptiform activity, although an exact cutoff is not specified in the International League Against Epilepsy (ILAE) criteria, and some authors use lower thresholds (eg, more than 50 percent) [7].

With sophisticated imaging and nuclear medicine techniques, the epileptiform process can be shown to originate in the language cortex of the dominant temporal lobe and secondarily to spread to homologous cortex in the other hemisphere and beyond [16]. No structural abnormalities are typically seen on routine neuroimaging with computed tomography (CT) or magnetic resonance imaging (MRI). However, volumetric analysis of MRI in four children with typical LKS has shown volume reductions of 26 to 51 percent in the bilateral superior temporal areas [17], regions that correspond to the auditory association cortex. It is unclear if this focal cortical atrophy is the cause of LKS or the result of intractable epileptiform activity [18].

The deterioration of language in these children may be caused by an interruption of the normal maturation of the cortex in the temporal lobes during a critical period of development when the brain is making new synapses and removing ("pruning") others. The pervasive epileptiform activity is thought to activate and perpetuate synaptic connections that would, in the course of normal development, be removed. There is evidence that cognitive functioning improves if epileptic activity is reduced [19,20]. The involvement of both temporal lobes eliminates the possibility that an uninvolved temporal lobe can subsume the function of the other as so often occurs in children with lesions that disrupt the dominant speech cortex early in development.

Epileptic encephalopathy with continuous spikes and waves during sleep (CSWS) — CSWS is an epileptic encephalopathy characterized by seizures, developmental regression in at least two domains, and an EEG pattern of ESES. It is a rare condition that makes up less than 1 percent of patients seen in pediatric epilepsy centers [21]. The etiology of CSWS is unknown in many cases, but up to half of patients may have a structural cause identified and some may carry causative genetic mutations in GRIN2A. (See 'Developmental and epileptic encephalopathy with spike-wave activation in sleep (DEE-SWAS)' above.)

As with LKS, children with CSWS exhibit normal or only mildly abnormal development until approximately two to four years of age, when they begin having seizures. Seizures during the initial stage often occur out of sleep and are typically unilateral clonic or tonic-clonic [22]. Additional seizure types may include atonic and atypical absence seizures, occasionally progressing to nonconvulsive status epilepticus. There is typically a marked increase in the frequency and types of seizures within the first few years after seizure onset. This is accompanied by a severe neurocognitive regression that occurs around five to six years of age in most patients [22]. Unlike LKS, regression is seen across a wide spectrum of domains, including language, behavior, learning, memory, attention, social interactions, motor skills, and global intelligence.

During wakefulness, the EEG typically shows focal or multifocal spikes. As in LKS, the hallmark EEG feature of CSWS is ESES, characterized by continuous or near-continuous bilateral or occasionally lateralized slow spikes and waves occupying at least 85 percent of non-REM sleep.

Treatment and prognosis — There are no controlled clinical trials that have investigated treatment in LKS or CSWS, and there is significant regional variation in the approach. As with most types of epilepsy, surgical intervention is considered early for lesional cases. Anecdotal evidence suggests that early initiation of antiseizure medications and control of epileptic activity improves long term prognosis.

Antiseizure medications with some reported benefit include valproate, clonazepam, levetiracetam, and others; polytherapy is often needed [19,20,23]. A trial of corticosteroids is recommended if there is not a rapid response to antiseizure medications [19,24]. High-dose nocturnal benzodiazepines have been reported to reduce epileptiform activity in more than half of patients with CSWS, in some cases accompanied by sustained clinical improvement [25]. The effectiveness of therapy is measured by the patient's clinical response (ie, control of seizures), improving developmental milestones, and the proportion of spike-wave activity on overnight EEG recordings.

Some patients with LKS and CSWS may benefit from surgical treatment, but the approach must be individualized [24]. Multiple subpial transection is one such approach [26]. Subpial transection consists of closely spaced slicing of the temporal lobe gyri involved in the epileptic process, with interruption of the short cortical-cortical fibers in the white matter immediately under the cortical gray. This limited slice disrupts the epileptic interconnections and stops the epileptiform activity while sparing the thalamocortical fibers that subserve normal cortical function. The results can be quite dramatic, with complete disappearance of the epileptiform activity on the EEG and rapid return of language function. Despite the rather extensive transections undertaken in some patients, few postoperative deficits have been noted. Other surgical approaches in selected patients include lesionectomy, corpus callosotomy, and hemispherectomy [27].

Despite aggressive treatment, some patients with LKS have persistent, intractable epilepsy, and most patients have residual language dysfunction that diminishes their quality of life [28]. Patients with CSWS typically have more severe neurocognitive regression and worse long-term neurocognitive outcomes, particularly those with underlying structural causes [12].

Relationship with autism — LKS is sometimes considered on the differential diagnosis of pervasive developmental/autistic spectrum disorders, but the relationship is a tenuous one, at best [29]. The two syndromes initially were linked by two clinical similarities: loss of language after a period of relatively normal language acquisition and seizures. Uncontrolled evoked potential studies purportedly have shown abnormalities in the auditory cortex in children with autism even with normal EEGs and have been used to support the contention of temporal lobe dysfunction in this disorder. Scattered reports describe successful steroid therapy in children with LKS as well as in autism, also uncontrolled. Nevertheless, the two disorders are in reality quite different. The child with autism usually has a plateau or loss of language in the second half of the second year of life as compared with an older age in LKS, the EEG almost always is normal early in the course of autism, particularly at the time of language regression (although it may show epileptiform activity in over 20 percent at a later age), and one never sees the striking ESES pattern in autism. The characteristic social, motor, and communication abnormalities of autism are not seen in LKS. (See "Autism spectrum disorder in children and adolescents: Clinical features", section on 'Terminology'.)

FOCAL EPILEPSY SYNDROMES OF CHILDHOOD — Focal epilepsies of childhood are epilepsy syndromes that occur in developmentally and neurologically normal children and have a self-limited course, remitting prior to adulthood. The best-described of these syndromes are:

●Self-limited epilepsy with centrotemporal spikes (SeLECTS), formerly known as benign childhood epilepsy with centrotemporal spikes (BECTS) or benign rolandic epilepsy, makes up approximately 10 to 20 percent of all childhood epilepsies and has a mean age of onset between seven and nine years. The most common seizure type is a simple focal seizure with motor symptoms that initially involve the face, often with progression of the motor seizures to other areas of the body (the so-called Jacksonian march). Focal seizures evolving to a bilateral convulsive seizure (also called secondarily generalized seizures) are also common and are often the presenting symptom; the clinician may not be able to elicit a history of focality in such cases. Seizures are more common at night and the characteristic electroencephalogram (EEG) abnormality of centrotemporal spikes is also more prominent in sleep recordings. In most cases, seizures remit within two years.

●Childhood occipital visual epilepsy, formerly known as benign occipital epilepsy of childhood (Gastaut type), produces frequent seizures with prominent visual symptoms (hallucinations, blindness). The mean age of onset is between eight and nine years. EEG reveals occipital spikes that are activated by eye closure.

●Self-limited epilepsy with autonomic seizures (SeLEAS), formerly known as Panayiotopoulos syndrome, presents at a mean age of less than five years with a distinctive seizure type that has prominently autonomic features, including vomiting and skin pallor. The seizures are usually nocturnal and last more than five minutes. One-third to one-half of episodes last more than 30 minutes.

These disorders are discussed in detail separately. (See "Self-limited focal epilepsies of childhood".)

ABSENCE EPILEPSIES — Absence seizures (also called petit mal or generalized nonconvulsive seizures) are a common pediatric seizure type associated with a range of generalized epilepsy syndromes. Typical absence seizures consist of brief staring episodes with behavioral arrest that may occur tens to hundreds of times daily. They are associated with generalized 3-hertz spike-and-slow-wave discharges on EEG. Atypical absence seizures have a less clear time of onset and resolution than typical absence seizures, and they are often manifest as less complete periods of activity arrest but with impairment of responsiveness or other behavioral changes.

Several epilepsy syndromes with markedly different clinical courses and prognoses have absence seizures as the only or most predominant seizure type. The age of onset and clinical phenotypes of the absence epilepsy syndromes are quite variable and often help to define the particular syndrome (figure 1). The clinical expression of absence seizures themselves may differ from one syndrome to the other; as an example, in epilepsy with myoclonic absences (EMA), EEG spikes are followed by prominent myoclonic jerks that may cause the child to fall, whereas in children with the more common childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE), the spikes are not associated with myoclonus.

Although the age of onset, clinical manifestations of the seizures, neurologic status of the children, and prognosis differ among the various syndromes, the EEG patterns are quite similar and the approach to treatment is fundamentally the same, with ethosuximide, valproic acid, lamotrigine, and clonazepam considered to be the most effective antiseizure medications. (See "Childhood absence epilepsy", section on 'Treatment'.)

The other seizure types that accompany the absences are more specific for the particular syndrome. The Lennox-Gastaut syndrome (LGS) and myoclonic-astatic epilepsy (MAE; also referred to as myoclonic-atonic epilepsy) are more serious epilepsy disorders in which children always have other seizure types, including tonic and atonic seizures, as well as developmental delay or regression in association with the epilepsy.

The neurologic and cognitive status of the child also varies from syndrome to syndrome. Children with CAE, juvenile myoclonic epilepsy (JME), and JAE usually are neurologically and cognitively intact. Relatively minor behavioral, psychiatric, and cognitive impairments are reported in a minority [30-32]. (See "Juvenile myoclonic epilepsy", section on 'Clinical features' and "Childhood absence epilepsy", section on 'Clinical features'.)

By contrast, children with LGS and MAE have epileptic encephalopathies with motor and cognitive impairment as well as abnormalities on imaging studies, including evidence of an earlier brain injury and developmental and maturational disorders. Children with EMA fall somewhere in between, with approximately 44 percent having intellectual disability prior to the onset of the seizures at 1 to 12 years of age (mean 7 years) [33]. Children with LGS and MAE have life-long neurologic deficits, and many continue to have seizures into adulthood.

JUVENILE MYOCLONIC EPILEPSY — Juvenile myoclonic epilepsy (JME) is frequently diagnosed in pediatric epilepsy clinics but is often not recognized by referring clinicians. Typically, the patient is a healthy young teenager with one or more of the following seizure types:

●Myoclonic jerks (most frequent in the morning, within the first hour after awakening)

●Absence seizures ("typical" petit mal seizures that often precede the other seizures and begin toward the end of the first decade)

●Generalized tonic-clonic seizures, which also tend to occur upon awakening

The clinical presentation, diagnosis, and treatment of JME are discussed separately. (See "Juvenile myoclonic epilepsy".)

REFLEX EPILEPSIES — Reflex seizures are epileptic seizures that are triggered by specific external sensory stimuli or internal cognitive processes [34,35]. In certain epilepsy syndromes, all or nearly all seizures are reflex seizures, including the following [36]:

●Primary reading epilepsy

●Startle epilepsy

●Hot-water epilepsy

●Idiopathic photosensitive occipital lobe epilepsy

●Other visual-sensitive epilepsies (eg, Sunflower syndrome) [37,38]

Reflex seizures may also occur along with spontaneous seizures in other generalized or focal epilepsy syndromes, including [34]:

●Myoclonic epilepsy of infancy (see "Overview of infantile epilepsy syndromes", section on 'Myoclonic epilepsy in infancy')

●Dravet syndrome (see "Dravet syndrome: Genetics, clinical features, and diagnosis")

●Childhood absence epilepsy (see 'Absence epilepsies' above)

●Juvenile myoclonic epilepsy (see 'Juvenile myoclonic epilepsy' above)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Epilepsy in children (The Basics)")

●Beyond the Basics topics (see "Patient education: Seizures in children (Beyond the Basics)" and "Patient education: Treatment of seizures in children (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Lennox-Gastaut syndrome – The Lennox-Gastaut syndrome (LGS) is a lifelong, severe developmental epileptic encephalopathy associated with the onset of seizures in childhood, treatment-resistant epilepsy, and intellectual disability. Children usually present in the first seven years of life with multiple seizure types, particularly tonic and atonic seizures; an atypical, slow spike-wave pattern on EEG; and intellectual disability, often with behavioral impairments. (See "Lennox-Gastaut syndrome".)

●DEE-SWAS – Developmental and epileptic encephalopathy with spike-wave activation in sleep (DEE-SWAS) includes the formerly named epileptic syndromes of Landau-Kleffner syndrome (LKS), which affects primarily language function, and continuous spikes and waves during sleep (CSWS), which is associated with more global neurocognitive regression. (See 'Developmental and epileptic encephalopathy with spike-wave activation in sleep (DEE-SWAS)' above.)

•Children with the LKS develop normally until approximately three to six years of age, when they begin to lose language function. Approximately 75 percent of children with LKS have clinical seizures, but they are rarely severe. Children with CSWS typically have a more severe seizure disorder and more global developmental regression. Characteristic EEG abnormalities include bilateral centrotemporal spikes and sharp waves that spread widely throughout both hemispheres. During sleep, epileptiform activity becomes continuous. (See 'Landau-Kleffner syndrome' above and 'Epileptic encephalopathy with continuous spikes and waves during sleep (CSWS)' above.)

•Early initiation of antiseizure medications and control of epileptic activity may improve long term prognosis. Other treatment options include corticosteroids and epilepsy surgery. (See 'Treatment and prognosis' above.)

●Focal epilepsy syndromes of childhood – Self-limited epilepsy with centrotemporal spikes (SeLECTS), childhood occipital visual epilepsy, and self-limited epilepsy with autonomic seizures (SeLEAS) are idiopathic syndromes that occur in developmentally and neurologically normal children and have a benign course, remitting prior to adulthood. (See "Self-limited focal epilepsies of childhood".)

●Absence epilepsies – Absence seizures are the only or most predominant seizure type in several epileptic syndromes, which have markedly different clinical courses and prognoses. The age of onset and clinical phenotypes of the absence syndromes often help to define the particular syndrome. (See 'Absence epilepsies' above.)

●JME – Juvenile myoclonic epilepsy (JME) can include any one or more of the following seizure types: myoclonic jerks, absence seizures, and generalized tonic-clonic seizures. The typical patient is neurodevelopmentally normal and presents after 10 years of age. Sleep deprivation may be required to elicit the typical 4 to 6 hertz polyspike and wave pattern on EEG. Seizures are usually controlled with a broad spectrum antiseizure medication. (See "Juvenile myoclonic epilepsy".)