basic science / EEG correlate Flashcards
Equilibrium potential for an ion can be calculated by:
Nernst Equation
Equation to determine resting membrane potential
Goldman-Hodgin-Katz equation
Situations in which scalp discharges can be positive (downward deflecting) - 2
- Craniotomy
- infants with IVH (central)
Non-epileptic causes for occipital discharges (2, likely more)
- Migraine (occipital)
- Congenital blindness
Spike-and-wave discharges:
1.0-2.5 Hz
3-3.5 Hz
4-6 Hz
1.0-2.5 Hz: LGS
3-3.5 Hz: Absence Epilepsy
4-6 Hz: JME
BiPLEDS can signify what?
severe brain disesase. (associated with poor prognosis)
How to differentiate between Myoclonic-Astatic seizure and negative myoclonus (in FLE with rapid bilateral synchrony)
MAS: Geralized slow spike-and-wave or polyspike-and-wave with jerk
NM: interrupts tonic activity, no evidence of myoclonia during drops
What is the intracellular pathophysiological mechanism of an epileptiform discharge?
What is the primary cause?
Paroxysmal depolarizing shift (PDS):
Primarily due to activation of high-frequency fast sodium channel potentials
List five (5) ways to reduce risk of electrocution in EEG recording
- Small leakage currents
- short cord connection
- people NOT connected to ground
- High-resistant contacts
- one common ground electrode
minimal surface area of the postsynaptic action potential required for recording of a spike on scalp EEG
6 cm2
What determines the half-life of a resistor?
Time-constant
What is aliasing?
How do you avoid it?
How do we know this?
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
Seizures occur in ___% of patients with :
Anterior temporal spikes
90%
Seizures occur in ___% of children with rolandic spikes
40%
Seizures occur in ___% of children with occipital spikes
40%