What are the risk factors for seizures?

Risk Factors for Seizures

The major risk factors for seizures include brain injury, structural brain abnormalities, metabolic disturbances, toxic exposures, and genetic predisposition. Understanding these risk factors is essential for proper management and prevention of seizures.

Classification of Seizures

Seizures are broadly classified into two main categories:

1. Provoked (Acute Symptomatic) Seizures:

   • Occur within 7 days of an acute neurologic, systemic, metabolic, or toxic insult 1
   • Not considered epilepsy by themselves 2
   • Examples include seizures due to hyponatremia, alcohol withdrawal, toxic ingestions, and encephalitis 1

2. Unprovoked Seizures:

   • Occur without acute precipitating factors 1
   • Include remote symptomatic seizures (resulting from brain or systemic injury that occurred >7 days ago) 1
   • May be idiopathic (no established cause) 1
   • Recurrent unprovoked seizures define epilepsy 2

Major Risk Factors for Seizures

Structural Brain Abnormalities

• Brain tumors and mass lesions 1
• Stroke and cerebrovascular disease 1
• Traumatic brain injury 1
• Vascular malformations 1
• Developmental abnormalities 1
• Cortical dysplasia 1

Brain Injury and Trauma

• Severe TBI increases seizure risk by 17 times compared to the general population 3
• Risk factors specific to post-traumatic seizures:
  • Brain contusion with subdural hematoma 3
  • Skull fracture 3
  • Loss of consciousness or amnesia lasting >24 hours 3
  • Subdural hematoma (31% vs. 21% in non-seizure patients) 4
  • Craniectomy 1

Metabolic Disturbances

• Electrolyte abnormalities, particularly:
  • Hyponatremia 1, 5
  • Hypocalcemia 1
  • Hypomagnesemia 1
• Hypoglycemia and hyperglycemia 1
• Uremia 1
• Liver failure 5

Toxic and Substance-Related Factors

• Alcohol use and withdrawal 1, 5
  • History of alcohol dependence increases risk (25% vs. 11% in non-seizure patients) 4
• Medication toxicity or withdrawal 5
• Recreational drug use 1

Infections

• CNS infections (encephalitis, meningitis) 1, 6
• Systemic infections with neurological involvement 6

Demographic and Other Factors

• Advanced age (≥65 years) increases risk 3, 4
• African-American ethnicity shows higher risk in some studies 4
• History of previous seizures 1
• Family history of seizures 1
• Immunocompromised status 1
• Eclampsia in pregnant women 1

Special Considerations

Provoked vs. Unprovoked Seizures

• Approximately one-third to one-half of patients with a first unprovoked seizure will have a recurrent seizure within 5 years 1
• For patients with 2-3 recurrent unprovoked seizures, the risk of recurrence within 5 years increases to about 75% 1

Post-Traumatic Seizures

• Early seizures occur within 7 days after brain injury (incidence ~2.2%) 1
• Delayed seizures occur after 7 days (incidence ~2.1%, but 11.9% in the first year for severe TBI patients) 1
• The risk of seizures after TBI varies greatly according to injury severity and time since injury 3

Medical Illness and Seizures

• Many medical illnesses can cause seizures even without directly injuring the brain 6
• Seizures in medically ill patients often have a single underlying cause that may be reversible 5
• In-hospital seizures occur in approximately 0.4% of all TBI patients and are associated with higher rates of complications and worse outcomes 4

Clinical Implications

• Patients with a first seizure should be evaluated for underlying causes, particularly those that are potentially reversible 5
• Patients with risk factors for recurrent seizures may benefit from closer monitoring and earlier intervention 1
• For patients with provoked seizures, treating the underlying cause is the primary approach rather than initiating antiepileptic medication 1
• Antiepileptic prophylaxis is generally not recommended for primary prevention of post-traumatic seizures 1

Understanding these risk factors helps clinicians identify patients at higher risk for seizures, implement appropriate preventive measures, and provide timely treatment when seizures occur.