Focal Epileptiform Abnormalities and Disorders

Vocabulary flashcards covering the definition, morphology, and localization of focal epileptiform discharges and benign variants from the Diagnostic EEG lecture.

Epileptiform activity

Paroxysmal electrical activity that stands out from background rhythms, characterized by spike or sharp wave morphology, surface negativity, and an after-going slow wave.

Spike

A type of epileptiform discharge with a duration of less than $70\,msec$.

Sharp wave

A type of epileptiform discharge with a duration between $70\,msec$ and $200\,msec$.

John Dunne's Rule

The concept that epileptiform activity "Keeps bad company," meaning it is often associated with a local background abnormality.

Fp1/Fp2

Electrode locations corresponding to the inferior frontal region.

F7/F8

Electrode locations corresponding to the anterior temporal or fronto temporal region.

T3/T4

Electrode locations corresponding to the mid temporal region.

T5/T6

Electrode locations corresponding to the posterior temporal region.

Cz

The electrode location representing the vertex or central midline.

TIRDA

Temporal Intermittent Rhythmic Delta Activity; a pattern of intermittent slowing that has specificity for mesial temporal lobe epilepsy.

Centrotemporal Spikes

Stereotyped discharges often featuring a triphasic morphology with a brief preceding positive spike, a prominent biphasic sharp wave with a rounded peak, and a small negative slow wave.

BSSS (Benign Small Sharp Spikes)

Low amplitude ($<50\,\mu V$) and short duration ($15\,msec$) spikes occurring during drowsiness and light sleep in young adults; also known as Small Sharp Spikes.

Wicket waves

Monophasic spike-like discharges occurring in trains of $6-11\,Hz$ during drowsiness and light sleep in older adults, typically in temporal regions.

6-Hz spike-and-wave

Brief trains ($<2\,secs$) of $5-7\,Hz$ spike-and-wave activity seen during wakefulness and drowsiness, where the spike is low amplitude and the slow wave is more prominent.

14 & 6 positive bursts

Brief bursts ($0.5-1\,sec$) of "negative" arciform waveforms with "positive" spiky components at $14\,Hz$ or $6-7\,Hz$, max at posterior temporal regions.

Interictal discharges

Epileptiform patterns and discharges that occur between seizures, as opposed to ictal patterns which occur during a seizure.