Focal evolution following apparent interictal period on scalp electroencephalography in generalized epilepsy: a...

Area of Science:

• Neurology
• Epileptology
• Clinical Neurophysiology

Background:

• Scalp video EEG (vEEG) monitoring is crucial for epilepsy diagnosis.
• Classifying epilepsy types, particularly distinguishing generalized from focal epilepsy, is essential for effective treatment.

Purpose of the Study:

• To classify epilepsy type in patients with focal evolution following a generalized spike-and-wave complex (GSWC) on vEEG.
• To analyze the diagnostic utility of specific EEG patterns in epilepsy.

Main Methods:

• Retrospective review of 389 adult patients undergoing vEEG.
• Categorization of ictal EEG into three phases: GSWC, bilateral background activity, and focal evolution.
• Analysis of clinical and EEG findings, including interictal EEG and MRI.

Main Results:

• Identified five ictal recordings from three patients exhibiting a specific GSWC-to-focal evolution pattern.
• Patients presented with bilateral tonic-clonic seizures and normal cognition, with no structural abnormalities on MRI.
• EEG pattern suggested genetic generalized epilepsy over focal epilepsy, with effective treatment using sodium valproate and lamotrigine.

Conclusions:

• An apparent interictal period can precede focal evolution in generalized epilepsy, mimicking focal epilepsy on scalp EEG.
• This pattern requires careful diagnostic consideration to avoid misclassification.
• Accurate identification of epilepsy type based on EEG signatures is critical for patient management.