PediaNotes

Seizures in Infancy and Childhood

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I. Etiology: Causes of Convulsions

The etiology is highly age-dependent. Causes are broadly classified into Acute Symptomatic (Provoked) and Epilepsy (Unprovoked/Recurrent).

A. Age-Based Etiological Classification

Age GroupCommon CausesLess Common / Serious Causes
Infancy
(< 1 Year)		Febrile Seizures (6 mo–5 yrs)
CNS Infections: Meningitis, Encephalitis
Metabolic: Hypoglycemia, Hypocalcemia, Hyponatremia
Structural: Post-HIE sequelae, IVH porencephaly		Inborn Errors of Metabolism: Pyridoxine dependency, Aminoacidopathies
Malformations: Cortical dysplasia, Lissencephaly
Genetic/Syndromes: Dravet syndrome, West syndrome (Infantile Spasms)
Trauma: Non-accidental injury (Shaken Baby)
Childhood
(> 1 Year)		Febrile Seizures (Peak 18 mo)
Infections: Neurocysticercosis (NCC), Tuberculoma (Endemic regions)
Idiopathic Epilepsy: BECTS, Childhood Absence Epilepsy		Trauma: Post-traumatic seizures
Toxins: Lead, organophosphates, drug overdose (TCA, antihistamines)
Tumors: Astrocytoma, DNET
Neurocutaneous: Tuberous Sclerosis, NF-1

B. Mechanistic Classification

  1. Febrile Convulsions: Most common cause in childhood (3–4%). Occurs between 6 months and 5 years; associated with rapid rise in temperature (non-CNS infection).
  2. Infectious (Acute): Bacterial meningitis, viral encephalitis (HSV, JE), cerebral malaria.
  3. Granulomatous (Chronic): Neurocysticercosis (NCC) and Tuberculoma are the leading causes of focal seizures in developing countries (DNB High Yield).
  4. Metabolic:
    • Transient: Hypoglycemia, Electrolyte disturbances (Na+, Ca++, Mg++).
    • Inborn Errors: Biotinidase deficiency, Urea cycle disorders (usually present in infancy).
  5. Vascular: Arterial ischemic stroke, Venous sinus thrombosis (dehydration/infection related).

II. Investigation of a Case of Convulsions

The goal of investigation is three-fold:

  1. Verify if it is a true seizure (vs. mimic).
  2. Identify the underlying cause (Provoked vs. Epilepsy).
  3. Classify the seizure type for management.

1. History (The Diagnostic Cornerstone)

  • Event Description: Open eyes vs closed (psychogenic usually closed), limb movements (sync/async), duration, cyanosis, sphincter loss.
  • Aura/Pre-ictal: Epigastric rising, fear (Temporal); Flashing lights (Occipital).
  • Post-ictal: Todd’s paresis (lateralizing sign), duration of confusion, sleep.
  • Triggers: Fever, sleep deprivation, flashing lights, missed meals.
  • Developmental History: Milestones, regression (neurodegenerative).
  • Family History: Febrile seizures (AD inheritance), Epilepsy, Sudden death (Channelopathies).

2. Clinical Examination

  • Vitals: Temperature (Infection), BP (Hypertensive encephalopathy), HR (Arrhythmia).
  • Anthropometry: Head circumference (Microcephaly = congenital; Macrocephaly = Hydrocephalus/Sotos).
  • Neurocutaneous Markers (Phakomatoses):
    • Hypopigmented macules (Ash leaf): Tuberous Sclerosis.
    • Café-au-lait spots/Axillary freckling: Neurofibromatosis Type 1.
    • Port-wine stain: Sturge-Weber Syndrome.
  • Neurologic Exam: Signs of meningeal irritation, focal deficits, fundoscopy (Papilledema/Chorioretinitis).

3. Laboratory Investigations

  • Tier 1: Acute/First Seizure (Emergency)
    • Blood Glucose: Bedside glucometry (Hypoglycemia is a treatable emergency).
    • Electrolytes: Na+ (Hyponatremia), Ca++, Mg++ (infants).
    • Infection Screen: CBC, CRP (if febrile).
  • Tier 2: Specific Indications
    • Toxicology Screen: If poisoning suspected.
    • Metabolic Workup: Ammonia, Lactate, ABG, Urine ketones (if unexplained lethargy/vomiting/FTT).

4. Neuroimaging

  • Urgent CT Head:
    • History of trauma (bleed/fracture).
    • Signs of raised ICP (exclude mass effect before LP).
    • Persistent altered sensorium.
    • Focal neurological deficit.
    • High Yield: Best modality to detect calcified Neurocysticercosis or Tuberculoma.
  • MRI Brain (Epilepsy Protocol):
    • Gold standard for non-emergent or recurrent seizures.
    • Detects: Cortical dysplasia, Mesial Temporal Sclerosis (MTS), tumors, vascular malformations.

5. Electroencephalogram (EEG)

  • Indications: All children with unprovoked seizures (after the first seizure to assess recurrence risk).
  • Timing: Ideally within 24–48 hours; sleep-deprived EEG increases yield.
  • Findings:
    • 3 Hz Spike & Wave: Absence Epilepsy.
    • Centrotemporal Spikes: Rolandic Epilepsy (BECTS).
    • Hypsarrhythmia: West Syndrome.
    • Generalized Polyspike: Juvenile Myoclonic Epilepsy (JME).

6. Lumbar Puncture (CSF Analysis)

  • Mandatory: Infants < 6 months with fever and seizure.
  • Indicated: Signs of meningitis (Kernig/Brudzinski), bulging fontanelle, or fever without focus in infants 6–12 months (immunization status dependent).
  • Contraindicated: Signs of raised ICP, hemodynamic instability, skin infection at puncture site.

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