What are the top 5 etiologies of seizures in young patients?

Top 5 Etiologies of Seizures in Young Patients

In young patients, the five most common etiologies of seizures are: (1) idiopathic/unknown cause, (2) febrile seizures, (3) CNS infections (meningitis/encephalitis), (4) hypoxic-ischemic injury (particularly in neonates), and (5) metabolic derangements (hypoglycemia, electrolyte abnormalities).

Age-Dependent Etiology Patterns

The etiology of seizures in young patients varies dramatically by age, requiring a stratified approach:

Neonatal Period (0-28 days)

• Hypoxic-ischemic encephalopathy dominates as the primary cause, accounting for 46-65% of neonatal seizures, with 90% occurring within the first 2 days of life 1, 2, 3
• Intracranial hemorrhage and perinatal ischemic stroke combined represent 10-12% of cases 2, 3
• Metabolic derangements including hypoglycemia, hypocalcemia, hypomagnesemia, and hyponatremia are critical treatable causes 1, 3
• CNS infections become more likely when seizures occur beyond day 7 of life 2
• Genetic disorders and malformations of cortical development increase in likelihood after the first week 2, 3

Infancy and Early Childhood (1 month - 5 years)

• Febrile seizures are the most common seizure disorder of childhood, occurring in 2-4% of young children 4, 5
• CNS infections (meningitis, encephalitis) represent 15% of seizures in pediatric emergency presentations 6
• Prolonged febrile seizures account for 7.6% of status epilepticus cases in this age group 6
• Systemic infections triggering seizures are common, with fever-induced hyperexcitability being the primary mechanism 7, 8
• Structural brain abnormalities emerge as important causes in patients younger than 18 years 6

Older Children and Adolescents

• Idiopathic/unknown etiology represents 27-44% of cases in comprehensive evaluations 9
• Drug toxicity and intoxication become increasingly relevant, with cocaine and other substances causing acute seizures 9
• Epilepsy with poor medication compliance accounts for 21.7% of status epilepticus presentations 6
• Trauma-related seizures increase in frequency, though precise incidence is difficult to estimate 4

Critical Diagnostic Priorities

Immediate Life-Threatening Causes to Exclude

The diagnostic approach must prioritize rapid identification of treatable causes:

• Point-of-care glucose testing is mandatory to exclude hypoglycemia immediately 1, 3
• Electrolyte abnormalities (sodium, calcium, magnesium) require urgent assessment, as 8% of seizure patients have correctable metabolic abnormalities 9
• Meningitis must be excluded in all febrile seizure patients, as seizures are the presenting sign in one in six meningitis cases, and one-third of these lack meningeal signs 7
• Hypocalcemia and hypomagnesemia must be corrected before initiating anticonvulsants 1, 3

Age-Specific Diagnostic Considerations

For neonates:

• The systematic evaluation identifies the underlying cause in approximately 95% of cases 1, 2
• MRI with diffusion-weighted imaging is the gold standard for identifying etiology 1, 3
• Lumbar puncture should be avoided in comatose infants due to herniation risk 1, 3

For children with febrile seizures:

• Lumbar puncture is indicated if age is less than 12-18 months, especially under 12 months 1
• The primary diagnostic concern is always excluding CNS infection 7
• Imaging studies are necessary only in selected cases with focal findings or complex features 7, 5

Common Pitfalls and Caveats

Misdiagnosis Risks

• In alcohol-related seizures, clinicians must eliminate symptomatic causes before labeling as withdrawal seizures, as increased alcohol use correlates with unprovoked seizures rather than true withdrawal 9
• Not all clinical movements in neonates have EEG correlates, and many EEG seizures lack clinical manifestations 1
• Brief myoclonic movements do not confirm epileptic seizures; distinction depends on synchrony, rhythmicity, and number of movements 1

Critical Metabolic Oversights

• History and physical examination fail to predict metabolic abnormalities in approximately 2-3 cases per 100 seizure patients 9
• Hypoglycemia was unsuspected in multiple studies despite being readily treatable 9
• Hyponatremia from psychogenic water drinking can present without obvious historical clues 9

Infection-Related Considerations

• In HIV-positive patients with new-onset seizures, 40% have acute lesions necessitating admission, but only one-third have abnormal physical examination findings 9
• Febrile patients have a 55% likelihood of CNS infection if presenting with seizures 9
• Blood culture, urine culture, and empirical antibiotics should be initiated immediately when infection is suspected 1, 3