Epileptic and Epileptiform Encephalopathies Clinical Presentation

Updated: Jul 26, 2022
  • Author: Masanori Takeoka, MD; Chief Editor: Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP, FANA  more...
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The history in patients with epileptic encephalopathy varies with the specific syndrome.

Early infantile epileptic encephalopathy (Ohtahara syndrome)

Early infantile epileptic encephalopathy (EIEE) is a rare disorder characterized by early-onset seizures in the neonatal period, which may begin as early as the first few days of life. Brief generalized tonic seizures typically occur first, occasionally in clusters. Focal motor and hemiconvulsive seizures may occur in up to half of cases. [34]

Most children are symptomatic from structural brain abnormalities such as cerebral dysgenesis, although metabolic disorders are also reported. [44]

Early myoclonic encephalopathy

Early myoclonic encephalopathy (EME) is a rare disorder characterized by neonatal-onset seizures, usually within the first month of life.

Seizures are mostly myoclonic and partial motor seizures. Myoclonic seizures may be focal, occasionally very subtle, and may become frequent. Tonic spasms may develop later. This is different from EIEE, in which tonic seizures appear early.

Infantile spasms (West syndrome)

West syndrome usually occurs in the first year of life and consists of the triad of infantile spasms, developmental deterioration, and a hypsarrhythmia pattern on EEG.

The epileptic spasms are brief, generalized seizures involving extension and/or flexion axially and of the extremities. An individual spasm lasts seconds, often longer than typical myoclonic seizures, though not as long as most tonic seizures.

The spasms may be subtle and may be isolated at onset, typically clustering later in the course. Several clusters per day, particularly in drowsiness, are characteristic.

Malignant epilepsy with migrating partial seizures in infancy

Onset of this rare syndrome occurs in the first year of life, in some cases in the neonatal period. It is characterized by frequent partial seizures of multifocal onset, with autonomic or motor involvement. The seizures increase in frequency and may become nearly continuous.

Severe myoclonic epilepsy of infancy (Dravet syndrome)

Severe myoclonic epilepsy of infancy (SMEI) is an uncommon disorder with onset between 3 months and 2 years of age. The epilepsy begins with recurrent simple febrile seizures, which later become of longer duration and occur when the patient is afebrile.

Myoclonic seizures, either focal or generalized, appear after age 1 year. Multiple seizure types develop, including hemiclonic, simple motor, complex partial, and atypical absence seizures. Episodes of status epilepticus are common.

Myoclonic status in nonprogressive encephalopathies

This rarely reported disorder has onset in infancy or early childhood, with onset usually during the first year of life. [28] Seizures typically begin with partial motor seizures, although myoclonic status may occur at onset. Myoclonic absences, massive myoclonias, and rarely generalized or hemiclonic seizures may occur.

Myoclonias may be multifocal and occur with startles. Myoclonic status epilepticus may be recurrent. Motor abnormalities and movement disorders are common.

Myoclonic-astatic epilepsy (Doose syndrome)

Myoclonic-astatic epilepsy (MAE) is a rare syndrome occurring in early childhood, usually before age 5 years. Children are previously normal, and there is a slight male predominance to the syndrome. A history of febrile seizures or generalized epilepsy with febrile seizures "plus" (GEFS+) may be present.

Initial seizures are generalized tonic-clonic (GTC), followed by myoclonic seizures that increase in frequency. Frequent falls are characteristic and are due to myoclonic or atonic seizures or both. Multiple seizure types, including atypical absence and tonic seizures in addition to myoclonic, atonic, and GTC seizures, may occur. Nonconvulsive status epilepticus (NCSE) is common.

Lennox-Gastaut syndrome (LGS)

Lennox-Gastaut syndrome (LGS) is a mixed seizure disorder with onset in early childhood and a very refractory course resulting in significant cognitive impairment. Onset is often before age 5 years.

The most commonly reported seizure types are tonic, atonic, and atypical absences. Myoclonic, GTC, and focal seizures may also occur. Seizures may begin with infantile spasms, which then evolve into multiple seizure types. Nocturnal tonic seizures are most characteristic, with atypical absences and atonic seizures also occurring in most patients.

Tonic and atonic seizures may cause frequent falls and injury, resulting in the need for protective helmets for some patients. Seizures are very frequent, and episodes of convulsive and nonconvulsive status epilepticus are common.

A broad range of acquired and developmental etiologies has been described, including cerebral malformations, encephalitis, and hypoxic-ischemic injury. [29] From 70-78% of LGS cases are symptomatic (ie, have an identified cause). Development is often delayed in symptomatic cases, whereas development may be normal in idiopathic cases.

Landau-Kleffner syndrome and epilepsy with continuous spikes-waves during slow sleep

Landau-Kleffner syndrome (LKS) is a rare epilepsy syndrome occurring in early childhood, with onset usually between 3 and 10 years of age. [45] It was first described in 1957, when Landau and Kleffner reported on 6 children who presented with aphasia after apparently normal language acquisition. Since then, LKS has been recognized as an epileptic syndrome characterized by language regression, an abnormal EEG, and absence of specific underlying brain pathology.

The disorder is more common in boys, and most children have previously normal development. Patients develop an acquired verbal auditory agnosia early in the course, mimicking difficulty hearing, or "word deafness." Aphasia and language regression follow, along with seizures and behavioral problems in most children. Most have normal preceding language development, and the loss of language function is considered to be secondary to the near continuous epileptiform discharges in the superior temporal gyrus and adjacent cortical areas. Behavioral problems reported include aggression, emotional lability, disinhibition, and hyperactivity.

Epilepsy with continuous spike-waves during slow sleep (CSWS), like LKS, is a rare epilepsy syndrome occurring in early childhood. Peak onset is between 3 and 5 years of age. [46] Most children have normal development until the syndrome manifests. In contrast to LKS, which primarily affects language, children with CSWS develop more global cognitive impairment.

CSWS and LKS are not always completely distinct; overlap is seen in some cases. In CSWS, deficits in attention, language, memory, and visuospatial skills are reported. As in LKS, behavioral problems may occur, including aggression, emotional lability, disinhibition, and hyperactivity.

With LKS and CSWS, seizures may be either rare or very frequent and difficult to control. Multiple seizures types are characteristic. Atonic, absence, partial motor, and generalized convulsive seizures may occur.

Benign childhood epilepsy with centro-temporal spike discharges (benign rolandic epilepsy)

Benign rolandic epilepsy (BRE) is the most common epilepsy syndrome of childhood and has a peak onset between 7 and 10 years of age, with resolution by adolescence. The most common seizures are brief partial motor seizures involving the face and pharyngeal muscles, usually occurring at night. A tendency toward secondary generalized tonic-clonic seizures also exists.

Autistic regression with epileptiform EEG findings

An increased risk of epilepsy is associated with autism, but the role of epilepsy in this disorder remains unclear. In most autistic children, including the approximately one third with developmental regression, epilepsy does not play an obvious role in their symptoms.

In children with autism, there is no difference in the incidence of regression between children with and without epilepsy, suggesting that epilepsy does not increase the risk of regression in autism. [47] Epilepsy is present in up to 38% of autistic children and more may have epileptiform abnormalities present on their EEG. [48]


Physical Examination

A thorough general and neurological evaluation may aid in identifying a specific underlying etiology; however, findings may be normal in some cases. An evaluation by a geneticist may be useful when dysmorphic features are present.



The complications of epileptic and epileptiform encephalopathies usually are secondary to the treatment, especially with antiepileptic drugs (AEDs) or high-dose steroids. However, the psychiatric and psychological problems associated with a neurological handicap, especially a neurodegenerative process, can have a great impact on both the child and the family. In LKS and some cases of CSWS, behavioral and emotional disturbances are the major problems encountered.