What are the different types of seizures in children?

Types of Seizures in Children

Pediatric seizures are fundamentally classified into three main categories: focal onset seizures (arising from one hemisphere), generalized onset seizures (rapidly affecting both hemispheres from onset), and seizures of unknown onset. 1, 2

Primary Classification Framework

The International League Against Epilepsy classification system divides seizures based on their origin in the brain, which is critical for treatment selection and prognosis 3, 1:

Focal Onset Seizures

• Arise within networks of a single cerebral hemisphere and may remain localized or become more widely distributed 1, 2
• Can be further subclassified by whether awareness is intact or impaired 4
• Motor subtypes include: automatisms, atonic, clonic, epileptic spasms, hyperkinetic, myoclonic, and tonic movements 4
• Non-motor subtypes include: autonomic, behavior arrest, cognitive, emotional, and sensory manifestations 4
• May evolve to focal to bilateral tonic-clonic seizures (previously called "secondary generalization"), which start focally then propagate to both hemispheres 3, 1
• Recurrence rate up to 94%, considerably higher than generalized seizures 1
• Show 50% positive findings on CT when neurologic examination is focal, compared to only 6% for generalized seizures 1

Generalized Onset Seizures

• Rapidly affect both hemispheres and both sides of the body from onset without warning or aura 3, 5, 2
• Divided into motor and non-motor (absence) categories 3

Motor generalized seizures include: 4

• Tonic-clonic (grand mal)
• Clonic
• Tonic
• Myoclonic
• Myoclonic-tonic-clonic
• Myoclonic-atonic
• Atonic
• Epileptic spasms

Non-motor generalized seizures (absence) include: 4

• Typical absence (petit mal)

• Atypical absence

• Myoclonic absence

• Eyelid myoclonia

• Have genetic underpinnings in most cases, particularly in neurologically normal children 3, 2

• Recurrence rate of 72%, lower than focal seizures 1

Age-Specific Seizure Presentations

Neonatal Seizures

• Represent a distinct category requiring specialized evaluation 3
• Often have different underlying etiologies than older children 3

Infantile Seizures

• Can be broadly categorized into three groups: infants with myoclonic seizures, infants with spasms, and infants with focal seizures 6
• Each category has both benign and severe presentations with unique features 6
• May be difficult to classify precisely into "focal" or "generalized" categories, particularly in intractable cases 6

Febrile Seizures (Special Category)

Simple febrile seizures: 3

• Occur in children 6-60 months of age
• Last less than 15 minutes
• Are generalized without focal component
• Occur once in 24 hours
• Do not cause long-term adverse effects including IQ decline, academic problems, or structural brain damage 3
• Risk of developing epilepsy by age 7 is approximately 1% (same as general population) 3
• Recurrence risk is 50% if first seizure occurs before 12 months of age, 30% if after 12 months 3

Complex febrile seizures: 3

• Prolonged (>15 minutes)
• Have focal features
• Occur more than once in 24 hours

Clinical Implications for Diagnosis

Key Distinguishing Features

• Presence of any focal feature is independently associated with clinically relevant abnormalities on neuroimaging 1
• The presence of aura suggests focal rather than generalized seizures 5
• Staring episodes without documented loss of awareness should NOT be used to diagnose absence seizures 5

Underlying Structural Causes

Certain seizure types are associated with structural brain lesions including: 1

• Tumors
• Infection
• Infarction
• Traumatic brain injury
• Vascular malformations
• Developmental abnormalities
• Seizure-associated brain pathology

Common Pitfalls

• Focal seizures with impaired awareness can mimic absence seizures but typically have focal features, may have auras, and show different EEG patterns 1, 5
• Carbamazepine is effective for partial and generalized tonic-clonic seizures but absence seizures (petit mal) do not appear to be controlled by carbamazepine 7
• Approximately one-third of children have seizures refractory to medications, particularly with focal-onset seizures 8