Criteria For Epileptiform Eeg Discharges

Generated with sparks and insights from 10 sources

Introduction

Epileptiform discharges on EEG are characterized by distinct attributes that differentiate them from normal brain activity.
Key features include sharp Morphology, amplitude changes, abrupt polarity shifts, and other deviations that disrupt typical EEG patterns.
Classification typically requires meeting certain criteria such as morphology, duration compared to background, and presence of after-going slow waves.
Typical epileptiform patterns include spikes lasting 20-70ms, sharps lasting 70-200ms, and associated slow wave components.
These patterns are used to identify and locate areas of Cortical excitability, which can indicate a Seizure onset zone.

Paroxysmal: Epileptiform discharges stand out sharply against the background EEG, showcasing bursts of abnormal activity.
Morphology: These discharges possess distinct sharp or spiky shapes, with strong peaks in amplitude.
Duration: Spikes occur within a timeframe of 20-70ms, and sharps last between 70-200ms, aligning with specific time criteria.
Polarity: Abrupt polarity changes mark these discharges, distinguishing them from other EEG patterns.
Slow Waves: Following spikes or sharps, slow waves occur as neurons enter a refractory period.

Morphology: Sharp or spiky morphology often signals epileptiform activity, measured in milliseconds.
Background Disruption: The EEG baseline shows disruption, either flattening or alteration in voltage activity.
Waveform Asymmetry: Differing left and right waveform patterns can indicate epileptiform changes.
Field Presence: The field 'ripples' should affect surrounding EEG electrodes, confirming the presence of a true discharge.
Interictal Activity: Utilized in diagnosis when combined with patient seizure history.

Spike-and-wave: Regularly associated with 3-Hz Spike-and-wave discharges, indicating absence seizures.
Sharp Transients: High amplitude sharp waves can highlight Focal seizures or irritability.
Rhythmic Patterns: Consistent rhythmic activities such as FIRDA, GIRDA may not be epilepsy indicators.
Periodic Discharges: Lateralized or generalized patterns may suggest an underlying structural issue.
Paroxysmal Activity: Showcased in Generalized epilepsy like Lennox-Gastaut Syndrome, often indicating tonic seizures.

Diagnostic Aid: Interictal activity serves as an adjunct to identify seizure onset zones.
Cortical Excitability: Presence of discharges indicates hyperexcitability and risk factors for seizures.
Patient history: EEG results may integrate with patient seizure history for epilepsy diagnosis.
Treatment Decisions: Persistent patterns can guide therapeutic interventions and monitoring.
Seizure Management: Helps in both acute and chronic management of epileptic conditions.

Spike Localization: Identifying and localizing spike discharges aids in pinpointing potential seizure zones.
Temporal discharges: Temporal discharges indicate focal irritability; patterns differ anteriorly and posteriorly.
Generalized vs. Focal: Discharges often distinguish between focal with rapid bisynchrony and truly generalized patterns.
Frontal Complications: Frontal discharges pose challenges due to dipole orientation and deep structure involvement.
Electrode placement: Accurate electrode placement crucial for identifying true discharge origins.