Seizure Syndrome Type

Seizure syndromes

  • Neonatal seizures - These occur between 0 and 1 month of age. They are often caused by some identifiable factor, so a thorough search must be made. This includes the consideration of CNS infection (since it is often treatable). In this category, the prognosis is determined by the underlying cause. For example perinatal asphyxia carries a guarded prognosis, whereas seizures due to hypocalcemia usually resolve fully.
  • Seizures with onset from 2 months to 3 years - In this age group, seizure disorders are polarized - that is, they tend to be at the extremes of the spectrum from benign to devastating.
    • Febrile seizures: (See also Febrile seizures) on the benign end of the spectrum. By far the most common seizure disorder of childhood, characteristically occurring between six months and six years of age. Tends to be familial. The primary issue is not the treatment of the seizure but identification of the cause of the fever, most often viral. 70% have no recurrence of the seizure, so anticonvulsants are unnecessary. Exceptions occur when a febrile seizure is particularly prolonged, or when they recur frequently.
    • Infantile spasms: (See also Infantile spasms (West syndrome)) on the devastating end of the spectrum. Typically begin between birth and one year, characterized by brief flexion jerks that may be confused with the Moro reflex. Associated with poor developmental outcome if they can be controlled. Determination of the underlying cause, which is possible in up to 75%of cases, is even more important to prognosis. A cause can be identified in up to 75% of cases, usually in those who are symptomatic at the time of the initial seizure. The EEG is always abnormal, with a hypsarrhythmia pattern.
    • Benign myoclonic seizures: the benign end of the spectrum, even though the seizure activity looks very similar to the more devastating infantile spasms. Natural history is spontaneous resolution, normal development, and normal EEGs.
    • Lennox-Gastaut Syndrome: on the devastating end of the spectrum. Typically begins between 1 and 3 years of age, but can occur as late as eight years. Usually multiple seizure types, including atonic, myoclonic, or atypical absence seizures, often on a daily basis. 80-90% have intellectual disability, and it is severe in half this number. One half to two-thirds have focal neurologic abnormalities, most commonly motor signs such as quadriparesis, spastic diplegia, and hemiparesis. It is usually seen in the context of a diffuse encephalopathic insult. There is no pathologic entity peculiar to the syndrome (i.e. there are no pathognomonic findings), and a presumptive cause cannot be determined in 30-35% of affected children.
    • Early infantile epileptic encephalopathy and early myoclonic epilepsy (Dravet syndrome): on the devastating end of the spectrum. Onset is between 0 and 6 months of age. Associated with developmental defects of the brain, and carries a very poor prognosis for both development and seizure control.
  • Seizures with onset between 3 and 10 years of age: the majority of children in this group have genetic epilepsies that carry a good prognosis
    • Absence epilepsy: (See also Absence Epilepsy). Usually begins between 4 and 7 years of age and is characterized by brief spells of "blanking out". It can be precipitated by 2-3 minutes of hyperventilation, and has a very typical EEG abnormality showing spike wave activity at a frequency of 3/sec. It is a genetically dominant trait, which resolves by puberty in more than 80% of children.
    • Benign focal epilepsy of childhood (Rolandic epilepsy or benign epilepsy with central temporal spikes of BECTS): Also begins between 4 and 7 years of age. Children have partial onset seizures that characteristically occur upon awakening from sleep. This is also a dominant genetic trait and also typically resolves by puberty. If the seizures are infrequent, many epileptologists now consider not using antiepileptic medications. Where warranted, oxcarbazepine or carbamazepinek is usually effective at low doses.
    • Grand mal epilepsy: The genetic variety of tonic-clonic epilepsy also has a predilection for occurring upon awakening. It may resolve by puberty.
    • Rasmussen syndrome: Is the cataclysmic onset of intractable partial (focal) seizures associated with cerebral inflammation, evolving into epilepsia partialis continua and progressive loss of motor function on the affected side. There is progressive atrophy of the brain and surgical resection is curative. It is thought to result from an autoimmune process against glutamate receptors in the cortex interrupted by a focal interruption of the blood brain barrier.
    • Landau-Kleffner syndrome: acquired aphasia, seizures and a behavioral disorder that develops before the age of 7 years in a child with normal early language development. It is characterized by verbal and auditory agnosia and progressive decline in language. The seizures typically begin between 5 and 10 years of age, disappear between 10 and 15 years, and are typically responsive to AEDs. Etiology is unknown.
  • Seizures with onset over the age of 10 years: These epilepsies may also have a genetic origin, but usually don't resolve spontaneously.
    • Juvenile absence epilepsy: same genetics and EEG as absence epilepsy and is also a "primary generalized epilepsy" but most patients also have tonic-clonic seizures plus absence seizures. Typically starts around age 12 or 13, with only a 50% spontanous remission rate.
    • Juvenile myoclonic epilepsy: (see also Juvenile myoclonic epilepsy (JME)). Also begins around age 12 or 13, but has a very characteristic pattern of myoclonic jerks during the first hour after awakening. This can be very disturbing or only a minor problem. Most patients also have occasional tonic-clonic seiures or absence seizures. The syndrome can be genetic, caused by an autosomal dominant mutation (with positive family history under direct questioning) or other nonprogressive static encephalopathy. It generally does not resolve spontaneously. EEG shows fast (3-5 Hz) spike and wave discharges. Seizures are often precipitated by sleep disruption or alcohol.
  • Seizures with onset at any age:
    • Partial seizures (either simple or complex): may begin at any age. If the seizures are caused by mesial temporal sclerosis, the child has complex febrile seizures or tonic-clonic seizures before the age of five. The seizures are then dormant for several years, but re-emerge in the teen-age years. If a child has complex partial seizures that begin at an earlier age, the probability of a tumor is much higher than in the older child.


Compiled and edited by: Lynne M Kerr, MD, PhD - 4/2013