Greenfield EEG Chapter 2 Flashcards Preview

Neurology > Greenfield EEG Chapter 2 > Flashcards

Flashcards in Greenfield EEG Chapter 2 Deck (28)
Loading flashcards...
1
Q

Distictive features of transition to Stage 1 Sleep (4)

A
  • Slowing and anterior spread of alpha activity follow by
  • Dropout of the posterior dominant rythym
  • Slow lateral eye movements seen in the lateral eye and frontal leads
  • Vertex sharp waves
2
Q

Eye-Ball Polarity

A

Cornea positive/Retina Negative

3
Q

Dropout of posterior dominant rythym in Stage 1 sleep is replaced by…

A
  • disorganized low amplitude mixture of frequencies

- theta activity predominating

4
Q

Vertex sharp waves (sign of late drowsiness) of stage 1 sleep are characterized by (amplitude, distrubution, morphology, duration)…

A

maximal amplitude (referential montages) and reverse phase (bipolar montage) at the Cz electrode

  • monophasic
  • surface negative
  • lasting 70-200ms, with highly variable amplitude
5
Q

Hypnogogic Hypersynchrony of children and adolescents may be associated with (frequency, amplitude)…

A

theta to delta frequency slowing (usually around 4Hz) with amplitudes as high as 300microV - NOTE: if seen with spike like features, only consider generalized epilepsy if occurs in other than drowsy states.

6
Q

Distictive features of transition to Stage 2 Sleep (2)

A
  • K complexes

- sleep spindles

7
Q

K complexes of Stage 2 Sleep are characterized by (amplitude, distribution, duration)…

A
  • high amplitude
  • diffuse to centrally predominant biphasic slow wave transients
  • last 0.5s
  • at least 75microV
8
Q

Sleep Spindles of Stage 2 Sleep are characterized by (morphology, frequency, amplitude, distrubution, duration, synchrony…

A
  • sinusoidal or spindle shaped (pointy at the ends
  • 12-14Hz
  • low amplitude
  • frontal to centrally
  • typically lasting 1-3 seconds
  • may occur asymmetrically but should overall be same amount on both sides
9
Q

The initial phase/deflection of a K-complex is..

A

Negative/Upward

10
Q

Besides Stage 2 sleep, K-complexes can be observed in

A

Brief Partial Arousals. e.g. can be demonstrated by lightly tapping pen on table during stage 2 sleep

11
Q

The defining waveform for Stage 2 sleep

A

Sleep Spindles

12
Q

Stage of Sleep associated with increased interictal epileptiform activity (reason sleep deprived EEG are ordered)

A

Stage 2

13
Q

Distictive features of transition to Stage 3 Sleep (aka. Slow Wave Sleep) (1/N)

A

-20% of the activity on a 30 second EEG recording is delta frequency
NOTE: delta of sleep requires a minimum of 2Hz or less (rather than 4Hz) and at least 75microV using a contralateral referential ear montage

14
Q

Distictive features of transition to REM Sleep (4)

A
  • Rapid Eye Movements
  • Low Amplitude (voltage)
  • Mixed Frequency
  • Low Amplitude EMG at the chin
15
Q

Posterior Occipital Sharp Transients of Sleep (POSTS) can occur in which stage of sleep?

A

Stages 1 or 2

16
Q

Posterior Occipital Sharp Transients of Sleep (POSTS) are characterzied by (morphology, distribution, frequency, rythmicity, synchrony

A
  • surface-positive monophasic
  • occipital distribution
  • 4-5Hz
  • arrythmic
17
Q

Arousal pattern from Stage 1 sleep is characterized by…

A

return of the alpha PDR

18
Q

Arousal pattern from Stage 2 or deeper sleep is characterized by (amplitude, morphology, duration…

A
  • high amplitude
  • biphasic or triphasic
  • lasts 0.5 sec or longer
19
Q

Activating Procedures are used to…

A

influence EEG activity that may reveal abnormalities that would not be seen otherwise

20
Q

What are the types of Activating Procedures (5)

A
  • Mental Alerting
  • Hyperventilation
  • Sleep
  • Eye Opending/Closure
  • Photic Stimulation
21
Q

How is Mental Alerting used as an activating procedure?

A

Used to distinguish pathological vs. state-dependent slowing of the PDR. e.g. calling name, counting 1-10, serial subtractions, spelling WORLD backwards

22
Q

How is Hyperventilation used as an activating procedure?

A

mechanism underlying changes in activity controversial; after 30-60sec theta slowing of PDR, with diffuse rythmic polymorphic activity theta range; continued hyperventilation may result in dramatically increased amplitude (several hundred microV) and further slowing to delta frequency (HIHARS/”buildup”

23
Q

How is Sleep used as an activating procedure?

A
  • Accomplished through behavioral techniques such as sleep deprivation. Must achieve Stage 2 sleep.
  • Activating for nearly all forms of epilepsy but notably in electrical status epilepticus of sleep, benign childhood epilepsy with centrotemporal spikes, juvenile myoclonic epilespsy,
24
Q

How is Eye opening and closure used as an activating procedure?

A

Eye opening blocks the PDR, Eye closure results in return of the PDR with faster frequency in first seconds after eye closure (aka “squeak”)
NOTE: in children with childhood epilepsy with occipital paroxysms (CEOM), the occipital spikes are sometimes suppressed by eye opening.

25
Q

How is Photic Stimulation used as an activating procedure?

A

Each strobe flash causes excitatory potential generated in the striate cortex (same waveform that occurs 100ms after VEP stimulus), best frequency varies for all individuals but is probably a harmonic of native PDR, absence of response is only abnormal if asymmetrical

26
Q

HIHARS

A

Hyperventilation-Induced High-Amplitude Rythmic Slowing

27
Q

What are the contraindications to Hyperventilation as an activating procedures? (5)

A
  • COPD or other chronic lung disease
  • pregnancy
  • recent stroke or SAH
  • sickle cell disease
  • moyamoya disease
28
Q

How can the photomyoclonic response or photoelectric response confuse photic stimulation results?

A
  • photomyoclonic response results from stimuli-induced eye blinking or facial twitching and is seen in frontal electrodes
  • photoelectric response results in activation of an electrical impulse of the frontal electrodes (RARE)