Seizures in Infancy and Childhood

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

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.