EEG - Electroencephalography Non-Epileptiform Abnormalities Questions and Answers

Question 1

An EEG recording from a 55-year-old patient in a drowsy state shows bilateral, synchronous, rhythmic 5-7 Hz sharply contoured waves over the parietal and posterior temporal regions.
The pattern has an abrupt onset and offset, lasts for approximately 45 seconds, and does not evolve in frequency or morphology.
The patient remains unresponsive to auditory stimuli during the event.
Which of the following non-epileptiform patterns is most likely being observed?

Accepted Answer

Subclinical Rhythmic Electrographic Discharge of Adults (SREDA)

Answer

Rhythmic Mid-Temporal Theta of Drowsiness (RMTD)

Answer

Wicket Spikes

Answer

14 & 6 Hz Positive Spikes

Question 2

A 68-year-old patient with a history of a craniotomy for a meningioma resection presents for a routine EEG. The recording shows a focal area of high-amplitude, sharp, and at times spiky-appearing 6-11 Hz activity directly over the surgical site. This activity is persistent across both awake and drowsy states. Which feature would most strongly differentiate this as Breach Rhythm rather than an epileptiform abnormality?

Accepted Answer

The absence of an after-going slow wave.

Answer

The presence of intermixed beta frequencies.

Answer

The high amplitude of the activity compared to the contralateral side.

Answer

Its focal and asymmetric nature.

Question 3

During a recording of a 25-year-old patient in light sleep, the technologist observes trains of 6-11 Hz arc-shaped (arciform), monophasic waves in the left temporal region. They occur without disrupting the background and are not followed by a slow wave. They sometimes appear as single transients that resemble sharp waves. This pattern is best described as:

Accepted Answer

Wicket Spikes

Answer

Mu Rhythm

Answer

Benign Small Sharp Spikes (BSSS/BETS)

Answer

Lambda Waves

Question 4

A patient is in a coma due to a severe metabolic disturbance. The EEG shows generalized, high-amplitude (>70 µV), periodically repeating waves at 1-2 Hz. Each wave has a distinct morphology: a small initial negative deflection, a large surface-positive sharp wave, and a following slow negative wave. This pattern is most consistent with:

Accepted Answer

Triphasic Waves

Answer

Frontal Intermittent Rhythmic Delta Activity (FIRDA)

Answer

Generalized Periodic Discharges (GPDs)

Answer

Burst-Suppression

Question 5

Which of the following non-epileptiform patterns is characterized by its location over the sensorimotor cortex, a frequency of 8-10 Hz, an arciform or comb-like morphology, and its attenuation with contralateral limb movement or the thought of movement?

Accepted Answer

Mu Rhythm

Answer

Posterior Dominant Rhythm (Alpha)

Answer

Rhythmic Mid-Temporal Theta of Drowsiness (RMTD)

Answer

Lambda Waves

Question 6

Positive Occipital Sharp Transients of Sleep (POSTS) and Lambda waves are two non-epileptiform patterns that share a similar morphology and occipital location. What is the primary distinguishing feature between them?

Accepted Answer

The patient's state of consciousness.

Answer

The polarity of the sharp component.

Answer

The frequency of the transients.

Answer

The symmetry of the waveforms.