Atypical EEG abnormalities in genetic generalized epilepsies

Area of Science:

• Neurology
• Clinical Neurophysiology
• Epilepsy Research

Background:

• Typical electroencephalogram (EEG) findings in genetic generalized epilepsy (GGE) include bilateral, symmetric, and synchronous generalized epileptiform activity.
• Atypical EEG abnormalities in GGE have not been systematically studied.

Purpose of the Study:

• To systematically investigate the prevalence and characteristics of atypical EEG abnormalities in patients with GGE.
• To identify factors associated with these atypical findings.

Main Methods:

• Validated GGE diagnoses were classified according to International League Against Epilepsy criteria.
• 24-h ambulatory EEG recordings were performed on all participants.
• Epileptiform discharges were analyzed for atypical features including amplitude asymmetry, focal onset/offset, atypical morphology, and generalized paroxysmal fast rhythm.

Main Results:

• Of 120 patients, 107 had abnormal EEGs, with 66.4% exhibiting at least one atypical epileptiform abnormality.
• Atypical morphology was the most common abnormality (93.4%), followed by amplitude asymmetry (28.0%) and focal discharges (21.5%).
• Significant associations were found between amplitude asymmetry and state of arousal/seizure-free duration, and between atypical morphology and state of arousal.

Conclusions:

• Atypical epileptiform EEG abnormalities are common in GGE and can be rare or frequent.
• The occurrence of these atypical findings may be influenced by the state of arousal and seizure-free duration.
• Recognizing these EEG variations is crucial for accurate GGE diagnosis and avoiding misdiagnosis.