Antiseizure Medication and EEG Abnormalities Quiz

Interictal Epileptiform Discharges (IEDs)

• Duration of transients for a discharge to qualify as IED is typically 20-70 milliseconds.
• Epileptiform abnormalities in EEG commonly associated with epilepsy include spikes, sharp waves, and spike-and-wave discharges.

Lateralized Periodic Discharges (LPDs)

• Previous name for LPDs is "lateralized periodic lateralized epileptiform discharges" (LPLEDs).

Conditions Associated with IEDs

• Conditions linked to IEDs, even without seizures, include brain injury, infections, and metabolic disturbances.

Drugs Without Association to IEDs

• Certain drugs, like lithium, are not associated with IEDs in the absence of seizures.

EEG Interpretation Limitations

• Inexperienced EEG interpreters may misidentify normal variations as pathologic findings, potentially reducing diagnostic specificity.

Characteristics of Sharp Waves

• Sharp waves are characterized by a quick transition from a baseline to a peak, distinct from slower waves in frequency.

Distinguishing Features of IEDs

• Most IEDs at the scalp present as high-voltage spikes or sharp waves, often localized to specific regions of interest.

Sensitivity and Probability Measures

• The sensitivity of finding an IED on a first routine EEG is approximately 60-70%.
• Probability of seizure recurrence in patients with normal EEGs after a first unprovoked seizure is about 30-50%.

Epilepsy Syndrome and IEDs

• Childhood epilepsy syndromes, particularly those like Landau-Kleffner syndrome, are almost invariably associated with IEDs.

Techniques to Increase IED Yield

• Sleep deprivation can enhance the yield of IEDs on interictal EEG recordings.

Prevalence and Specificity of IEDs

• Prevalence of IEDs in healthy children is around 2-5%.
• Specificity of IEDs in patients without a history of seizures is relatively low, causing potential misdiagnosis.