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• SREDA (subclinical rhythmic electrographic discharges of adults) . CORRECT
ANSWER: Sharply contoured theta activity in the posterior head region. A normal
variant in older adults during wakefullness.
• 14 and 6 positive spikes . CORRECT ANSWER: 1-2 seconds of sharply contoured
discharges in the posterior head regions in light sleep. Presents in adolescents.
• 6 hz spike and wave . CORRECT ANSWER: Midparietal low amplitude
discharges. Occurs in young adults in drowsiness and disappears in sleep.
• My rhythm . CORRECT ANSWER: Oscillating 10 hz waves seen in leads
overylying the senserimotor cortex in the absence of movement. If a patient
moves or thinks about moving their contralateral limb, this rhythm will be
suppressed.
• Wickets . CORRECT ANSWER: Symmetric monophasic sharp wave occuring
predominantly in older adults during light sleep in temporal leads without
disruption of the background.
• 3 hz slow wave activity . CORRECT ANSWER: 3 hz waves without an associated
spike which can be seen during hyperventilation in childhood
• RTTBD (rhythmic temporal theta bursts of drowsiness) . CORRECT ANSWER: 5-6
hz rhythmic waves in the temporal lobe. Seen in young adults during drowsiness.
,• Breach rhythm . CORRECT ANSWER: Unilateral high voltage iregular wave
rhythms due to alteration of conductance commonly seen in patients with a skull
defect.
• Anterior eye blinks (bells phenomenon) . CORRECT ANSWER: Positive
downward deflection, maximal in the frontopolar leads, followed by a negative
deflection from eye opening. Disappears in sleep.
• EKG . CORRECT ANSWER: Rhythmic electropositive discharges in one or
multiple leads, most often in the occipital leads. Time locked and synchronous
with the EKG tracing.
• Pulse . CORRECT ANSWER: Rhythmic slow waves in a single lead due to a close
pulsating vessel. Time locked but delayed after each QRS sample.
• Lateral eye movements . CORRECT ANSWER: Very slow out of phase derivations
involving anterior electrodes due to movement of the positively charged cornea.
Best appreciated in drowsiness and early sleep when patient experience rolling
eye movements.
• Muscle . CORRECT ANSWER: Extremely high frequency waves often generated
from the frontalis and temporalis muscles. Usually spares central leads.
Disappears in sleep.
• Glossokinetic . CORRECT ANSWER: Diffuse, low frequency discharges produced
by movements of the negative tip of the tongue. Can be induced by saying "la la la
la", chewing, or sucking.
, • Electrode pop . CORRECT ANSWER: Single or multiple sharp waves localized to a
single electrode without a surrounding field. Disappears by reapplying an
electrode.
• GRDA (generalized rhythmic delta activity) . CORRECT ANSWER: Generalized in
all leads, typically signifies global cerebral dysfunction, such as in a severe
encephalopathy, but is not to be a risk factor for seizure or seizure tendency.
• Frontally dominant GRDA . CORRECT ANSWER: Can be seen with a variety of
pathologies including posterior fossa lesions, intracranial lesions, and increased
intraventricular pressure.
• LRDA (lateralized rhythmic delta) . CORRECT ANSWER: Can be seen with focal
lesions such a hemorrhage, tumor, or stroke. Is associated with increased seizure
risk/seizure tendency.
• LPDs (Lateralized periodic discharges) . CORRECT ANSWER: Often seen with
focal acute or subacute cerebral dysfunction, such as with herpes simplex
enchephalitis, stroke, abscess, or subdural hematoma.
• GPDs (Generalized periodic discharges) . CORRECT ANSWER: Felt to have
highest seizure tendency of the 'ictal-interictal' patterns. If seen clinically with
rapidly progressive dementia it can be strongly suggestive of Creutzfeldt-Jakob
Disease.
• End stage liver disease . CORRECT ANSWER: This disease can present with
hyperammonemia and generalized periodic waves with triphasic morphology.
They are bilaterally synchronous and usually frontally predominant and exhibit
three phases (i.e. negative, positive, negative). Triphasic waves can also be seen in
ESRD and other forms of metabolic encephalopathy.