Epilepsy: Rowan's ch 1-4 Flashcards
What does an EEG record ?
Post-synaptic potentials (majority), action potentials and chronic neuronal depolarization but most likely the voltage of the EC matrix.
Two types of Post-synaptic potentials
Inhibitory and Excitatory
What is the PDR
posterior dominant rhythm is the basic rhythmic frequency of the normal awake adult brain.
What leads to rhythmic cortical activation
thalamic pacemaker cells.
What is the current system for placing electrodes ?
10-10
Odd numbered elctrodes are on the ___.
Left
Even numbered electrodes are on the ____.
Right
Potential fields are ___ in shape and have a ____ effect.
oval/ripple.
Bipolar Recording: If input 1 is negative with respect to input 2 the deflection is
upward
If input 2 is negative with respect to input 1 the deflection is ?
downward
negative phase reversal = ___
localization of focus
Referential recording
electrodes are compared to a reference (A1 for example)
What is an amplifier ?
Records potential difference between two electrodes
Bipolar recording
two successive electrodes are compared
Three types of montages
double bannana, transverse, circumferential
Overview of electronics.
…
Multifocal definition
discharge in more than 3 non-contiguous leads and two different hemispheres
Impedence should not exceed
5 kohms
Standard diplasy
30mm/sec with 10 sec pages
Standard sensitivity and brain death criteria
7 microvolts should be turned down to 2 for brain death criteria.
standard frequency of filters and should you even adjust them ?
1 to 70hz and no
Purpose of notch filter
set at 60hz to block out electronic devices.
Gamma, beta, alpha, theta and delta frequencies
> 30, 13-30, 8.5-13, 4-8.5, and 0-4
Acceptable asymmetry of PDR
2:1
Stage 1 sleep: 2 features
vertex waves and POSTs
Stage 2 sleep: 2 features
sleep spindles and k-complexes
Def of a slow PDR
<8.5 hz
Def sleep spindles
sinusoidal, synchronous and at 12-14 hz
Def of k-complexes
bi/triphasic waves >500ms
Long return to baseline after Hyperventialtion reason
hypoglycemia
4 normal variants
alpha, mu, lambda, 14/6
Define alpha variants
half to double the PDR is okay
define mu rhythm
se over c3/c4 (motor strip, attenuates with movement of the opposite limb
define lambdas
electropositive transients in occipital regions
define 14/6
14 hz and 6hz spikes singular and in clusters usually in posterior quadrants.
PDR does what with eye opening.
eye opening
What 2 things cause an abnormal background ?
Loss of PDR or lack of distinct sleep states
three levels of slowing
0-4 severe
4-7 hz moderate
7-8 hz - mild
Duration of spike
20-70ms
Duration of sharp
70-200ms
two types of rhythmic patterns
GRDA and LRDA
GPEDS are seen in what clinical states
diffuse injury (toxic-metabolic,hypoxic ischemic)
PLDs are seen in what clinical states
focal lateralized lesions (brain abscess etc)
Define evolution
2 unequivocal, sequential changes in frequency morphaology and location.
Principle of localization in bipolar montage ?
Phase reversal
Principle of localization in referential montage ?
Amplitude
