Ch 13 - Neurophysiology Flashcards
what is an EEG
summation of excitatory and inhibitory postsynaptic potentials of pyramid neurons.
How many cm2 of cortex is needed to produce an EEG field
6cm2
EEG = PPP + 6
How many frequencies on a delta wave? Theta? Alpha? Beta?
D = 0-4
T = 4-8
A = 8-13
B = >13
Dig That Awesome Beat
Upward vs downward EEG deflections:
Each EEG channel is a comparison of two inputs
+ > - = downward deflection
- > + = upward
Bipolar montage:
Input 1 and 2 are adjacent, and input 2 is input 1 in the next channel
Fp1 - F3
F3-C3
C3-P3
Referential montage:
Input 2 is presumed inactive
Fp1 - Cz
F3 - Cz
C3 - Cz
All channels are in reference to Cz
Hyperventilation during EEG is contraindicated in:
Stroke
Sickle Cell
Cystic Fibrosis
Congenital Heart Dz
Asthma
Moyamoya
Hyperventilation is a SSCCAM
Normal finding on EEG during hyperventilation?
Generalized background slowing
Prolonged slowing can be seen on hyperventilation on EEG if?
Patient is hypoxic or hypoglycemic
Photic stimulation is performed after what age?
>6 months old
photomyoclonic response to photic stim?
when muscle contractions, such as contraction of the eyelids occur during photic stim
photoparoxysmal response to photic stim?
when photic stim results in epileptiform discharge. This is seen in patients with JME
photoconvulsive response to photic stim?
When stim results in a seizure. (usually seen in primary generalized epilepsy)
Background rhythm on EEG with age?
At 3 mo, the posterior background rhythm should be 3Hz, and at 5 mo it should be 5Hz.
By age 3 yo, the awake background rhythm should reach alpha frequency.
Kappa waves?
low amplitude waves in the temporal regions of the alpha or theta frequency (4-13). They occur during cognitive tasks or thinking.
Phi Beta KAPPA members have complex thoughts.
Lambda waves?
positive sharp transients in the occipital area seen during visual scanning.
You can have lambda waves if you look around at a bunch of lambs.
Mu rhythm?
7-11 Hz activity seen best over the centroparietal regions. Attenuated by movement of the contralateral body.
Mu is attenuated by MUvement.
Wicket spikes/waves?
seen during drowsiness or light sleep in adults
6-11 Hz activity in the temporal region
Most adults are wicked drowsy at 6:11am
Posterior slow waves of youth?
delta activity with overriding alpha frequencies
14 and 6 positive bursts
seen during drowsiness and light sleep commonly in adolescents
bursts of arciform activity at 14 or 6 hz over posterior temporal head regions lasting for less than 3 seconds
Siz hertz spike and wave bursts/ phantom spike and wave
seen in teens and adults during wakefulness and drowsiness. Disappear in sleep
Bursts of diffuse 6 Hz very small spike and higher amplitude wave discharges lasting a couple seconds.
small sharp spikes of sleep
seen in drowsiness and light sleep in adults
brief, low voltage spikes over the temporal regions
Rhythmic temporal theta bursts of drowsiness/ psychomotor variant pattern?
seen in drowsiness in young adults
5-7 Hz sharply contoured theta activity that occurs in bursts in the temporal region
eyeblink artifact?
cornea is positive and retina is negative
When the eye closes, a positive deflection is seen in Fp1 and Fp2
When the eye opens, a negative deflection is seen
I’m positive that I’d like to close my eyes and take a nap
NEO has nice PECs
(remember positive is downward and negative is upward on EEG)
Lateral eye movement artifact?
usually produce an artifact on F7 and F8
Look Left = positive on F7 and neg F8
Look right = negative F7 and pos F8
You look in the direction of positivity
2 Types of alpha coma?
- posterior dominant alpha activity that is poorly reactive. (common in brainstem lesions)
- diffuse or frontal alpha activity that is poorly reactive.
Seen in anoxia
Alpha comas are seen in Anoxia and Arrest
Bancaud’s phenomenon?
When the alpha activity over one hemi does not attenuated with eye opening. The nonreactive hemi is abnormal
Beta coma?
high amplitude generalized beta activity
Commonly seen in encephalopathy 2/2 medication, and some acute brainstem lesions.
Beta has a BETter prognosis than alpha coma.
Beta coma may be when youre Buzzed
Alpha is awful, Beta is better
breach rhythm?
due to a skull defect, the EEG activity may be higher in amplitude and spiky looking.
burst suppression?
can be induced with pentobarbital or midazolam gtt
carries a very poor prognosis in the setting of hypoxic injury
delta activity on EEG?
if continuous and polymorphic, may be due to a structural lesion
Types of epileptiform discharges: Spike vs sharp waves?
spike = <70 ms in duration
sharp wave is 70-200 ms in duration
