What electrolyte disturbances can cause seizures in neonates and pediatric patients?

Electrolyte Disturbances Causing Seizures in Neonates and Pediatric Patients

Several electrolyte disturbances can cause seizures in neonates and pediatric patients, with hypocalcemia, hypomagnesemia, hyponatremia, and hypernatremia being the most clinically significant. These disturbances require prompt identification and careful correction to prevent neurological morbidity and mortality.

Primary Electrolyte Disturbances Associated with Seizures

Calcium Disorders

• Hypocalcemia: Most common primary metabolic cause of seizures in neonates 1
  • Severe hypocalcemia can cause neuromuscular excitability and seizures 2
  • Particularly concerning in preterm neonates
  • Can be aggravated by blood transfusions due to citrate binding calcium 2
  • Calcium gluconate is indicated for treatment of symptomatic hypocalcemia 3

Magnesium Disorders

• Hypomagnesemia:
  • Often accompanies hypocalcemia 2
  • Causes CNS and PNS irritability leading to seizures 4
  • Magnesium prevents or controls convulsions by blocking neuromuscular transmission 5
  • Correction of magnesium deficiency is essential even when treating hypocalcemia

Sodium Disorders

• Hyponatremia:

  • Can occur in neonates with inadequate sodium intake 2
  • Large variations in serum sodium concentration may impair neurocognitive outcomes in preterm infants 2
  • Rapid correction must be avoided (no more than 10 mmol/L in 24h, 18 mmol/L in 48h) to prevent pontine myelinolysis 6

• Hypernatremia:

  • Can cause cerebral seizures, somnolence, and even coma 6
  • In newborns, commonly caused by inadequate water intake relative to sodium intake 7
  • Correction rate should target 10-15 mmol/L/24h to prevent cerebral edema and seizures 7

Potassium Disorders

• Hyperkalemia:
  • Can occur in neonates following RBC transfusions 2
  • Risk of transfusion-associated hyperkalemic cardiac arrest (TAHCA) 2
  • Can cause cardiac arrhythmias but less commonly seizures directly

Risk Factors and Special Considerations

In Neonates:

1. Preterm infants: Higher risk due to:

   • Immature renal function
   • Higher insensible water losses
   • Limited capacity to generate glucose through glycogenolysis 2

2. Iatrogenic causes:

   • Medications prepared with sodium salts (e.g., benzylpenicillin) 7
   • Excessive sodium in parenteral nutrition
   • Rapid transfusions with stored blood products 2

3. Transitional physiology:

   • Normal ECF contraction after birth
   • Continuing natriuresis during transitional phase 2

In Older Pediatric Patients:

• Electrolyte disturbances are less likely to cause seizures in otherwise healthy children with first-time nonfebrile seizures 8
• More commonly associated with underlying conditions or critical illness 9

Diagnostic Approach

When evaluating a neonate or child with seizures:

1. Laboratory assessment:

   • Serum electrolytes (Na, K, Ca, Mg)
   • Serum glucose
   • Acid-base status
   • Serum and urine osmolality 9

2. Clinical assessment:

   • Hydration status
   • Weight changes (especially in neonates)
   • Medication review
   • Fluid intake and output 7

Management Principles

1. Hypocalcemia:

   • Administer calcium gluconate IV
   • Monitor for cardiac effects during administration
   • Caution in neonates: product may contain aluminum which can be toxic to premature neonates 3

2. Hypomagnesemia:

   • Administer magnesium sulfate
   • Monitor deep tendon reflexes (disappear as plasma level approaches 10 mEq/L) 5
   • Be aware that respiratory paralysis may occur at high levels

3. Sodium disorders:

   • Correct gradually to prevent neurological complications
   • For hypernatremia: use hypotonic fluids and target correction rate of 10-15 mmol/L/24h 7
   • For hyponatremia: restrict fluid intake in SIADH; use isotonic saline in hypovolemia 6

4. Timing of correction:

   • Acute disturbances: more rapid correction is better tolerated
   • Chronic disorders: must be corrected very slowly to prevent complications 9

Prevention and Monitoring

• Regular assessment of electrolytes in hospitalized neonates 7
• Careful monitoring during blood transfusions 2
• Maintain appropriate glucose infusion rates during blood transfusions 2
• Monitor serum electrolytes frequently during correction 7

Remember that electrolyte disturbances in neonates and children can present with nonspecific symptoms before seizures develop. Early recognition and treatment is essential for optimal management and satisfactory long-term outcomes.