basic science / EEG correlate Flashcards

1
Q

Equilibrium potential for an ion can be calculated by:

A

Nernst Equation

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2
Q

Equation to determine resting membrane potential

A

Goldman-Hodgin-Katz equation

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3
Q

Situations in which scalp discharges can be positive (downward deflecting) - 2

A
  • Craniotomy
  • infants with IVH (central)
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4
Q

Non-epileptic causes for occipital discharges (2, likely more)

A
  • Migraine (occipital)
  • Congenital blindness
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5
Q

Spike-and-wave discharges:
1.0-2.5 Hz
3-3.5 Hz
4-6 Hz

A

1.0-2.5 Hz: LGS
3-3.5 Hz: Absence Epilepsy
4-6 Hz: JME

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6
Q

BiPLEDS can signify what?

A

severe brain disesase. (associated with poor prognosis)

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7
Q

How to differentiate between Myoclonic-Astatic seizure and negative myoclonus (in FLE with rapid bilateral synchrony)

A

MAS: Geralized slow spike-and-wave or polyspike-and-wave with jerk
NM: interrupts tonic activity, no evidence of myoclonia during drops

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8
Q

What is the intracellular pathophysiological mechanism of an epileptiform discharge?

What is the primary cause?

A

Paroxysmal depolarizing shift (PDS):
Primarily due to activation of high-frequency fast sodium channel potentials

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9
Q

List five (5) ways to reduce risk of electrocution in EEG recording

A
  • Small leakage currents
  • short cord connection
  • people NOT connected to ground
  • High-resistant contacts
  • one common ground electrode
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10
Q

minimal surface area of the postsynaptic action potential required for recording of a spike on scalp EEG

A

6 cm2

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11
Q

What determines the half-life of a resistor?

A

Time-constant

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12
Q

What is aliasing?
How do you avoid it?
How do we know this?

A

What is aliasing?: erroneous representation of waveform due to low sampling rate
How do you avoid it: sampling rate should at least match double the frequency of the original signal
How do we know this? Nyquist sampling theorem

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13
Q

Seizures occur in ___% of patients with :
Anterior temporal spikes

A

90%

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14
Q

Seizures occur in ___% of children with rolandic spikes

A

40%

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15
Q

Seizures occur in ___% of children with occipital spikes

A

40%

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16
Q

SeLECTS, horizontal dipole is negative over ___ and positive is ____

A

Negative over central and temporal regions
postitive end over frontal region

17
Q

EEG features seen with syncope (2)

A

Transient high-voltage delta
complete voltage attenuation

18
Q

Factors increasing sensitivity of detection epileptiform discharges (6)

A
  • longer-term monitoring
  • higher yield if <24 hours since seizure
  • higher seizure frequency
  • lack of AED
  • epilepsy syndromes
  • Temporal location
19
Q

What causes:
Excitatory postsynaptic potential (EPSP)
Inhibitory postsynaptic potential (IPSP)
which is negative, which is positive?

A

EPSP: positive ions flow intracellularly (inward flow): Negative
IPSP: negative ions flow intracellularly (outward flow): Positive

20
Q

What is the passive source or sink in EEG terminology?

A

current flow in opposite direction further along the dendritic tree

21
Q

if a difference in potential between to electrodes is negative, you will see a _____ deflection.

A

Upward.