Reading and Reporting the EEG

Practice flashcards covering EEG terminology, analysis methods, and reporting structures based on the University of Sydney lecture by Andrew Bleasel.

Alpha rhythm

Rhythm at $8-13\,Hz$ occurring during wakefulness over the posterior regions of the head, generally with maximum amplitudes below $50\,\mu V$ in the adult. It is best seen with eyes closed and is blocked or attenuated by attention and mental effort.

Lambda wave

A diphasic sharp transient occurring over the occipital regions of waking subjects during visual exploration. The main component is positive relative to other areas and is time-locked to saccadic eye movement.

Paroxysm

A phenomenon with abrupt onset, rapid attainment of a maximum, and sudden termination, distinguished from background activity; commonly used to refer to epileptiform and seizure patterns.

Mu (\mu) rhythm

Activities in the alpha frequency band that differ from the alpha rhythm in topography and/or reactivity.

Hypnagogic hypersynchrony

Moderate/high amplitude, sinusoidal $3-5\,Hz$ bilateral activity occurring during drowsiness and awakening in young children ($2-5$ years), with maximum amplitude in frontal, central, and parietal regions.

Homotopic channels

Corresponding channels in the two hemispheres that are compared during EEG analysis to check for symmetry.

Slowing

Abnormal activity described by its frequency (theta, delta), distribution (bilateral, generalized, regional), rhythm (irregular, rhythmic), consistency (intermittent, continuous), and reactivity.

T3/4

Electrode locations used to describe mid temporal or centrotemporal distribution.

F7/8

Electrode locations used to describe anterior temporal or inferior frontal distribution.

T5/6

Electrode locations used to describe parietal distribution.

EEG Analysis Initial Steps

Steps include blinding to clinical history, checking the patient's age and state (alert, drowsy, sleep, coma), checking for skull defects, and changing montages.

EEG Report Structure

The formal structure includes clinical context (age, state, place), the body of the report (describing normal activity and abnormalities by type, morphology, frequency, location, and reactivity), and a conclusion.

Drowsiness Normal Variants

In children, this state can include dramatic changes such as spiky v waves and hypnagogic hypersynchrony which do not persist into sleep.