EEG Activation Procedures 3

Question 1

What is the recommended distance between the photic stimulator and the patient's eyes during intermittent photic stimulation?

Accepted Answer

30 cm

Answer

The standard distance for the photic stimulator is approximately 30 cm from the patient's closed eyes, providing adequate light intensity for activation while maintaining patient comfort and safety.

Question 2

Which activation procedure is most effective for provoking absence seizures during a routine EEG?

Accepted Answer

Hyperventilation

Answer

Hyperventilation is the most effective provocative maneuver for absence seizures, eliciting 3 Hz spike-and-wave discharges in approximately 80-90% of patients with untreated typical absence epilepsy.

Question 3

Eye closure sensitivity refers to which phenomenon during EEG recording?

Accepted Answer

Epileptiform discharges triggered specifically by the act of closing the eyes, distinct from normal alpha appearance

Answer

Eye closure sensitivity is a form of reflex epilepsy where epileptiform discharges are triggered by the act of closing the eyes, as opposed to the normal alpha rhythm that appears. It is distinct from fixation-off sensitivity.

Question 4

What is the purpose of recording a period of wakefulness with eyes open and eyes closed before activation procedures?

Accepted Answer

To establish the baseline EEG background including posterior dominant rhythm frequency, reactivity, and symmetry

Answer

Baseline awake recording with eyes open and closed establishes the posterior dominant rhythm (frequency, amplitude, symmetry, reactivity), identifies any focal or generalized abnormalities, and provides comparison for interpreting changes during activation procedures.

Question 5

Reflex epilepsy triggered by specific cognitive tasks (such as reading or calculating) is an example of:

Accepted Answer

Cognitive activation of seizures (thinking epilepsy or praxis-induced epilepsy)

Answer

Praxis-induced or cognitive-task-induced epilepsy is a form of reflex epilepsy where specific mental activities (reading, calculating, spatial tasks) trigger epileptiform discharges or seizures, most commonly in genetic generalized epilepsies.

EEG - Electroencephalography Practice Test

EEG - Electroencephalography Practice Test

EEG Activation Procedures 3