How should epilepsy be diagnosed and stated?

How to State the Diagnosis of Epilepsy

The diagnosis of epilepsy should be stated when a patient meets one of three criteria: at least two unprovoked seizures occurring more than 24 hours apart, one unprovoked seizure with a probability of recurrence ≥60%, or diagnosis of a specific epilepsy syndrome. 1, 2, 3

Diagnostic Criteria for Stating Epilepsy

The International League Against Epilepsy (ILAE) provides three specific pathways to diagnose and state epilepsy 1, 2:

• Two or more unprovoked seizures separated by more than 24 hours 1, 4, 5
• One unprovoked seizure with a probability of further seizures similar to the general recurrence risk after two unprovoked seizures (≥60% over the next 10 years) 1, 3
• Diagnosis of an epilepsy syndrome based on characteristic clinical features 1, 2

When Uncertainty Exists: A Critical Caveat

When uncertain about the epilepsy diagnosis, postpone stating the diagnosis rather than falsely diagnosing it, as this carries significant treatment and psychosocial implications. 1 This is a critical pitfall to avoid—premature labeling can lead to unnecessary medication exposure, driving restrictions, employment limitations, and psychological burden.

Three-Tiered Classification Framework for Documentation

When stating the diagnosis, use the ILAE three-tiered framework 2:

Level 1: Seizure Type Classification

• Focal onset (arising from networks within one hemisphere) 1, 2
• Generalized onset (rapidly affecting both hemispheres bilaterally) 1, 2
• Unknown onset (when seizure origin cannot be determined) 1

Level 2: Epilepsy Type Classification

• Focal epilepsy (most common form) 6
• Generalized epilepsy 2
• Combined focal and generalized 6
• Unknown 6

Level 3: Epilepsy Syndrome (When Applicable)

• Identify specific syndrome based on seizure type, age at onset, family history, physical examination, EEG findings, and neuroimaging 4, 2
• Syndrome identification provides crucial information about natural history, prognosis, and treatment selection 4

Essential Diagnostic Elements to Document

Etiologic Classification

State the underlying etiology using ILAE categories 6, 2:

• Structural (hippocampal sclerosis, tumor, focal cortical dysplasia, hemorrhage) 6
• Genetic 6
• Infectious 6
• Metabolic 6
• Immune 6
• Unknown 6

Note that multiple etiologic categories may coexist and are not hierarchical 6.

Distinguish Provoked vs. Unprovoked Seizures

• Provoked seizures occur due to acute precipitants (toxic/metabolic insults, medications, electrolyte abnormalities) and do NOT constitute epilepsy 7, 4
• Unprovoked seizures occur without acute precipitants and form the basis for epilepsy diagnosis 1, 4

This distinction is critical because provoked seizures are treated by addressing the underlying cause, not with antiepileptic drugs 4.

High-Risk Features That Support Epilepsy Diagnosis After Single Seizure

Document these factors when stating epilepsy after one unprovoked seizure, as they indicate ≥60% recurrence risk 4, 3:

• History of prior brain insult or injury 4
• EEG demonstrating epileptiform abnormalities 4, 3
• MRI showing structural lesion 4

Documentation Algorithm

When stating the epilepsy diagnosis, structure your documentation as follows:

1. State the diagnosis explicitly: "Epilepsy" (not just "seizure disorder") 1, 5
2. Specify which diagnostic criterion is met (two unprovoked seizures, one seizure with high recurrence risk, or syndrome diagnosis) 1
3. Classify seizure type (focal, generalized, or unknown onset) 1, 2
4. Classify epilepsy type (focal, generalized, combined, or unknown) 6, 2
5. Identify epilepsy syndrome if applicable 2
6. Document etiology using ILAE categories 6, 2
7. Note associated comorbidities 2

Common Pitfalls in Stating the Diagnosis

• Confusing provoked with unprovoked seizures: Medication-induced, alcohol withdrawal, or metabolically-triggered seizures are provoked and should NOT be labeled as epilepsy 7, 4
• Diagnosing epilepsy prematurely: After a single seizure without high-risk features for recurrence 1, 3
• Failing to distinguish pseudoseizures or syncope from true epileptic seizures: These require different diagnostic approaches and do not constitute epilepsy 7, 4
• Misclassifying focal vs. generalized epilepsy: EEG findings can be misleading (secondary bilateral synchrony in focal epilepsy, atypical abnormalities in >60% of generalized epilepsies) 8