Transcript I represents “Intermittent”

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.