Can dehydration precipitate seizures, especially in individuals with a history of epilepsy, brain injury, or metabolic disorders?

Can Dehydration Cause Seizures?

Dehydration itself does not directly cause seizures, but the severe electrolyte disturbances that result from dehydration—particularly hyponatremia—can precipitate seizures, especially in vulnerable populations including infants, individuals with epilepsy, and those with underlying metabolic disorders. 1

Mechanism: Electrolyte Imbalance, Not Fluid Loss

The seizure risk from dehydration is mediated through electrolyte abnormalities rather than volume depletion alone:

• Hyponatremia is the primary culprit: Acute and severe sodium disorders are the most common electrolyte disturbance causing seizures, and these may be the sole presenting symptom 1
• Seizures from electrolyte imbalances are classified as acute symptomatic seizures, not epilepsy, and do not require long-term antiepileptic treatment 1
• The mechanism involves altering the balance of excitation and inhibition in the cerebral cortex or changing osmolality 2

High-Risk Populations

Infants and Young Children (Highest Risk)

Infants are particularly vulnerable to hyponatremic seizures from water intoxication, which can occur through:

• Feeding excessive amounts of plain water (20-30 oz daily) instead of formula during illness with vomiting/diarrhea 3
• Overly diluted infant formula 4
• Commercial bottled water marketed for infants but lacking adequate sodium 4
• Hyponatremia accounted for 58% of afebrile seizures in children under 2 years in one series 5
• Infants of parents living in poverty who are uninformed about feeding risks are especially at risk 4

Patients with Pre-existing Conditions

• Individuals with known epilepsy: Dehydration is recognized as a common precipitating factor for breakthrough seizures 6
• Patients with brain injury: Fever control and hydration management are recommended in severe traumatic brain injury patients who have seizures or are at high risk 6
• Older adults with delirium: Dehydration is a common precipitating factor for delirium, which can present with altered mental status 6

Clinical Presentation

When dehydration-related electrolyte disturbances cause seizures, look for:

• Hyponatremia (serum sodium <127 mEq/L in symptomatic cases) 5
• Associated findings: lethargy, vomiting, hypothermia, and hyperglycemia 3
• Seizures may be the sole presenting symptom without other obvious signs of electrolyte disturbance 1
• EEG shows slowing of background activity but has little specificity for differentiating electrolyte causes 1

Management Algorithm

Acute Management

1. Identify and correct the underlying electrolyte disturbance rather than initiating antiepileptic treatment as first-line therapy 1
2. For hyponatremic seizures from water intoxication:
   • Fluid restriction 3
   • Salt replacement 3
   • Rapid identification and correction prevent permanent brain damage 1

Prevention in At-Risk Groups

For patients with epilepsy or brain injury:

• Maintain adequate hydration as part of multi-component seizure prevention strategies 6
• Fever control is recommended in severe TBI patients with seizures, as uncontrolled fever can precipitate secondary brain injury 6

For older adults at delirium risk:

• Screen for dehydration and malnutrition as potential causes 6
• Multi-component interventions including hydration management reduce delirium incidence in hospitalized patients 6

For infants:

• Never feed plain water or overly diluted formula to infants, especially during illness 3, 4, 5
• Parents should be educated that water intoxication represents a preventable cause of seizures 5

Critical Pitfalls to Avoid

• Do not assume all seizures in dehydrated patients are from volume loss alone—check serum sodium and other electrolytes immediately 1
• Do not start antiepileptic drugs before correcting electrolyte abnormalities in acute symptomatic seizures 1
• In infants with seizures, always inquire about water intake and feeding practices 4, 5
• In severe malaria with dehydration and shock, exclude hypoglycemia and seizures before attributing neurological deterioration to raised intracranial pressure 6
• Exercise-associated hyponatremia can cause seizures, coma, and death from cerebral edema in endurance athletes who over-hydrate 6