At what age does epilepsy typically present?

Age of Onset for Epilepsy

Epilepsy can present at any age, with the highest incidence rates occurring during infancy (144 per 100,000 person-years in the first year of life) and in elderly populations, with a second peak after age 65. 1, 2

Age Distribution Patterns

Epilepsy demonstrates a bimodal age distribution pattern:

Childhood Onset

• Infancy (0-1 year): Highest incidence rate at 144 per 100,000 person-years 2
• Ages 1-10: Incidence decreases to 58 per 100,000 person-years 2
• Cumulative incidence: 0.66% by age 10 years 2
• Median age at first seizure in childhood-onset epilepsy: 5.3 years 3

Adult/Elderly Onset

• Second peak occurs in elderly populations (≥65 years) 4
• Increasing trend: The incidence of epilepsy in the elderly has steadily increased over recent decades 4
• Etiology difference: Vascular causes (74.2%) predominate in elderly-onset epilepsy, while cryptogenic causes are more common in younger-onset epilepsy 5

Epilepsy Syndrome Distribution by Age

Childhood (0-15 years)

• Localization-related syndromes: 58.6% of childhood epilepsies 3
• Generalized syndromes: 29.0% 3
• Undetermined: 12.4% 3
• Common specific syndromes:
  • Benign rolandic epilepsy: 10% of childhood cases 3
  • Childhood absence epilepsy: 12.1% 3
  • Infantile spasms: 3.9% 3

Neonatal Period (0-29 days)

• Acute symptomatic causes predominate (identifiable in ~95% of cases) 1
• Common etiologies:
  • Hypoxic-ischemic injury: 46-65% 1
  • Intracranial hemorrhage and perinatal ischemic stroke: 10-12% 1
• Timing significance: Seizures within first 2 days typically relate to hypoxic events; seizures after day 7 more likely due to infection, genetic disorders, or malformations 1

Elderly (≥65 years)

• Primary etiology: Vascular causes (stroke history present in 51.6% of elderly-onset cases) 5
• Treatment differences: Elderly patients often respond to lower doses of antiepileptic drugs 5
• Comorbidities: Higher rates of cognitive impairment, psychiatric disorders, and diabetes mellitus 5

Clinical Implications and Pitfalls

1. Diagnostic challenges by age group:

   • Neonates: Seizures may be subtle and difficult to recognize clinically 1
   • Children: Febrile seizures (occurring in 2-4% of children between 6 months and 2 years) must be distinguished from epilepsy 1
   • Elderly: Presentation may be atypical or confused with other conditions; some cases initially present as status epilepticus 5

2. Misdiagnosis risks:

   • Approximately 34% of reported epilepsy diagnoses in children may be erroneous, often representing non-epileptic paroxysmal events 2
   • Validation of epilepsy diagnoses through medical record review is crucial 2

3. Age-specific management considerations:

   • Neonates and infants: Require specialized imaging protocols; MRI is the preferred modality 1
   • Elderly: May require lower doses of antiepileptic medications and have higher risk of drug interactions 5, 4

Prognosis by Age of Onset

• Overall: About 50% of cases achieve prolonged seizure remission 6
• Childhood onset: Generally better prognosis, especially for certain syndromes like benign rolandic epilepsy 3
• Elderly onset: Higher mortality risk due to comorbidities and etiology (particularly vascular) 4

Understanding the age-specific presentation patterns of epilepsy is essential for appropriate diagnostic workup, treatment planning, and prognostication.