Seizures, Focal and Generalized

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DESCRIPTION

Seizures arise from abnormal electrical discharges in the cerebral cortex that lead to alterations of consciousness, behavior, motor activity, sensation, or autonomic function. Epilepsy is a disease defined as (i) two or more seizures without acute provocation, (ii) one seizure and at least a >60% further risk of additional seizures, or (iii) diagnosis of an epilepsy syndrome. Seizures are classified as focal, generalized, unknown, and focal to bilateral based on where the seizure starts.

  • Focal seizure types
    • Awareness should be described as focal aware, focal impaired awareness, or awareness unknown.
    • Motor and other symptoms should be described as focal motor seizure and focal nonmotor seizure.
  • Aura is not in the updated classification but can still be used to describe a feeling at the beginning of a seizure.
  • Generalized seizure types:
    • Tonic–clonic
    • Absence
    • Myoclonic
    • Clonic
    • Tonic
    • Atonic
  • Unknown onset seizure types:
    • Epileptic spasms
    • Behavior arrest
  • Focal to bilateral seizure is used to describe a seizure that is focal in onset and evolves bilaterally.

EPIDEMIOLOGY

  • Epilepsy affects 0.5–1% of all children (birth through 16 years).
  • 120,000 children seek care annually in the United States for a seizure.
  • 4 to 10 per 1,000 children in developed countries have epilepsy.

ETIOLOGY

  • Structural
    • Brain tumor
    • Malformations of cortical development
    • Prior stroke
    • Trauma
  • Genetic
  • Infectious
    • Neurocysticercosis
    • Cerebral malaria
    • Congenital infections
  • Metabolic
    • Aminoacidopathies
    • Pyridoxine dependent epilepsy
  • Immune
    • N-Methyl D-aspartate (NMDA) receptor encephalitis
  • Unknown cause

RISK FACTORS

Genetics

  • Epilepsy is both polygenic and multifactorial.
  • There are currently over 900 single genes known to be associated with epilepsy in childhood.
  • Copy number variations encompassing deletions and duplications of various sizes have also been implicated in the genetics of epilepsy.
  • The risk of epilepsy with an affected primary relative increases from the population risk (1–2%) to 4–8%.
  • Epilepsy may also be a feature of other genetic disorders such as trisomy 21 and Angelman syndrome or be part of a larger neurodevelopmental presentation. An increasing number of de novo mutations are being identified in both severe and mild epilepsies.

COMMONLY ASSOCIATED CONDITIONS

  • The incidence of childhood-onset epilepsy associated with intellectual disability and cerebral palsy is 15–38%.
  • Epilepsy occurs in 8–28% of children with autism.
  • Attention-deficit/hyperactivity disorder (ADHD), depression, and anxiety

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