G is for generalized

• Activity that affects the brain as a whole, or is present in every channel of the EEG.

• Also can use the word diffuse.

7 y/o male being evaluated for episodes of starring off, occurring multiple times daily

H is for hyperventilation• Activation procedure consisting of deep regular breaths

of about 18-24 bpm. This causes constriction of cerebral arteriolar system and hypoxia (low levels of oxygen in the blood).

• Should be performed for 2-3 minutes• May cause normal high amplitude, generalized slowing

pattern known as a “build-up response”.• Performed to illicit 3Hz generalized spike and wave

discharges in patients with petit mal or absence seizures.

• Contraindications include: cardiovascular problems, respiratory disorders, extreme hypertenison, subarachnoid hemorrhage, or recent stroke.

6 y/o female being evaluated for behavioral problems…eeg to rule out seizures.

Pt is currently on no medications

H is also for history

• Document age, family history , pt symptoms, relevant medical history, behavior state of patient, last episode occurrence, medications, or auras.

• Date and time of recording should also be annotated. As well as record ID.

I represents “Intermittent”

• Term that means: happens sporadically. It is activity that may come and go.

K is for K-complex.• High amplitude delta wave activity that

occur diffusely, but predominately over the vertex region. The slow, delta wave activity may be followed by a short period of 8-12 cps alpha-like activity.

• Most prominate in stage II sleep.• Some sources say the are products of

slight arousal. • Best seen in a transverse montage.

L is for localization

• The act of isolating the origin of the abnormality.

• In a referential montage, localize by highest amplitude.

• In a bipolar montage, localize by phase reversal.

M is for montages..

• System of grouping electrode pairs in a specific order. • A referential montage consists of groupings of one active

(scalp) electrode, and one inactive (non-cephalic) electrode.

which exception of a Cz reference, where Cz is used as a reference site, but is technically active.

A bipolar montage consists of electrode groupings which are both active (scalp) electrodes.

N is for notch, or 60hz filter!

• An active setting used to filter out fast, 60cps artifact caused by electrical interference.

• When notch filter is on, it can rid 60Hz artifact ( very fast, black “fuzzy” recording), but it can attenuate frequencies as low as 10Hz.

• Source of artifact should be eliminated ( if possible) before the notch filter be used.

• Caused by: recording in an electrically hostile environment, a bad ground electrode, a bad scalp or reference electrode, high impedances, bad jackbox.

O is for OIRDA• Occipital Intermittent rhythmic delta

activity.

• This abnormal slowing recorded from the posterior head regions. Usually after a stroke or trauma.

P is for parameters

• The low filter will attenuate slower frequencies, but will not effect faster frequencies . The normal low filter setting is 1Hz. A higher LFF setting of 3Hz or 5Hz will attenuate greater amounts of slowing.

• The high frequency filter will attenuate higher frequencies, but will not effect the slower ones. A normal HFF filter setting is 70Hz. A lesser HFF setting of 35Hz or 10Hz will attenuate a greater amount of faster activity.

Parameters continued…….

• A normal paperspeed is 30mm/sec or 10sec/pg.

• To enhance slowing, use a slower paperspeed of 15mm/sec or 20sec/pg.

• In order to “spread out” faster frequencies to localize a abnormality, or to count out 60Hz contamination, increase the paperspeed to 60mm/sec, or 5sec/pg.

P also stands for polarity

• If input 2 is more positive than input 1, pen deflection will go up.

• If input 2 is more negative in relation to input 1, pen deflection will go down.

P is also for Photic Stimulation

• Activation procedure consisting of flashes of light focused on the pt’s facial region at selected frequencies.

• May produce a driving response, which is a normal variant, identified as sinusoidal waveforms produced in the posterior head regions that are half, equal to, or double the rate of the photic speed.

• May also produce abnormal responses: - Asymmetrical driving response ( driving response over only one side for

posterior head region - Photo-Paroxysmal Response ( Generalized spike/wave discharges that

often outlast the the photic stimulation. No clinical signs. - Photoconvulsive Response ( Pt sent into a T/C seizures that also outlast

the photic stimulation.

Q is for Quiescence

• Another term for inactivity or quietness.

• Used to describe the EEG of a neonate born at or before 22 weeks conceptual age.

R is for RECORD• Record must have be acquired within 12 months

of the exam.• Records must contain a minimum of 16

channels.• Records should not be indicative of: ECI, status epilepticus, surgical monitoring,

ambulatory, long term epilepsy monitoring, neonatal recordings.

• Record should contain at least one period of eye opening and closing.

S is for Sleep• In a 1947 study of 500 cases of epilepsy,

epileptic activity was more that twice as likely to occur during sleep.

• This is especially true in cases of temporal lobe epilepsy.

• Stage I characterized by attenuation of the background, slow rolling eye movements.

• Stage II defined by sleep spindles• Stage III defined as 20-50% of the record

Trace Alternant

T is for Time• Record should be a minimum of 20

minutes or 120 pages long no including calibration and bio-calibration

U is for Understand

»BREECH rhythm is not an acceptable abnormality.

V is for Vertex Sharp waves

• Appear between 3-6 months of life.

• Moderate to high amplitude, sharp and biphasic waves lasting 100-200msec in duration.

• Usually a surface negative wave, followed by a positive component.