Epilepsy

Resources

AES EEG Curriculum: This free curriculum, provided by the American Epilepsy Society, covers the basics of EEG. It includes EEG cases for you to interpret, with grading to assess your performance. 

International League Against Epilepsy Diagnostic Manual

The Atlas of Adult EEG by Dr Strayhorn

Instruction manual for the ILAE 2017 operationalclassification of seizure types

ILAE classification of seizure types checklist form

ACNS Standardized Critical Care EEG Terminology 2021: Reference Chart 

American Clinical Neurophysiology Society’s Standardized Critical Care EEG Terminology: 2021 Version 

Initial evaluation of seizure.

It is important to obtain a good history and physical on each patient you see for a new onset seizure. As the data often demonstrates, the frequency of different causes can vary wildly based on the patient's age, geographical location, and local prevalence of certain factors such as CNS infections. In general, a patient with a new onset seizure should have basic lab evaluation, brain imaging, and EEG. Additional studies such as lumbar puncture can be considered based on the individual patient's presentation. 

General Etiology of Adult-Onset Seizures

• Most common causes (vary across studies):

  • Stroke: 23–44%

  • Idiopathic: 16–51%

  • CNS infections: 21–38%

  • Metabolic causes: 10–26%

  • Brain tumors: ~4–8%

  • Neurocysticercosis: Up to 50% in endemic areas (e.g., Mexico)

• Variation in prevalence depends on:

  • Age distribution

  • Geographic location

  • Sample size

  • Endemicity of CNS infections

Etiology by Seizure Type

Generalized Seizures

• Most common cause: Idiopathic (33.9%)

• Other causes:

  • Metabolic (10.8–20.3%)

  • CNS infections (16.9–29.7%)

  • Stroke (10.2–29.7%)

  • Tumors (~2.7%)

Focal Seizures

• Most common cause: Stroke (27.3–41.5%)

• Other causes:

  • CNS infections (5.5–52.7%)

  • Brain tumors (5.4–22.2%)

  • Encephalomalacia with gliosis (up to 9.8%)

  • Idiopathic (4.9–33.3%)

  • MS, trauma (minor causes)

Status Epilepticus

• Most common cause: Metabolic (35.3%)

• Other causes: Stroke (17.5%), CNS infections (11.8%), brain tumors (11.8%)

Age-Wise Etiology

• <20 years: Idiopathic most common (44.4%)

• <40 years:

  • CNS infections most prevalent

  • All cases of cortical venous thrombosis occurred in this group

• >40 years:

  • Stroke becomes the dominant cause (95.6% of stroke-related seizures occur in this group)

• Brain tumors: Equally distributed across age groups

Kaur S, Garg R, Aggarwal S, Chawla SPS, Pal R. Adult onset seizures: Clinical, etiological, and radiological profile. J Family Med Prim Care. 2018;7(1):191-197. doi:10.4103/jfmpc.jfmpc_322_16