3 electrophysiology of epilepsy

Question 1

What is the general neuronal organization in the cortex?

Answer 1

large pyramidal neurons in vertical columns, with apical dendrite perpendicular to surface

Question 2

What does EPSP stand for?

Answer 2

excitatory post-synaptic potential

Question 3

What does IPSP stand for?

Answer 3

inhibitory post-synaptic potential

Question 4

What are the EEG recordings of?

Answer 4

cell membrane depolarization [Na channels]

cell membrane hyper polarization [Cl channels]

Question 5

In the special circuit (hippocampus) the perforate path was the input…what is the output?

Answer 5

subiculum

Question 6

Excitatory output of the pyramidal cells in the hippocampus are opposed by what?

Answer 6

recurrent inhibitory interneurons (GABA)

Question 7

What does the intralaminar thalamic cell inhibit? what does this cause?

Answer 7

• Thalamic relay neuron

- leaves the thalamic neuron primed for bursting activity

Question 8

The bursting activity of TRNs is mediated by what?

Answer 8

calcium channels

Question 9

What does electroencephalography record?

Answer 9

the extra-cellular voltage potential of a population of cortical neurons
–6 cm/electrode

Question 10

In the normal EEG what does the alpha rhythm represent?

Answer 10

Awake state

Question 11

In the asleep EEG what stage is the vertex sharp waves?

Answer 11

Stage N1

Question 12

What asleep EEG stage is the sleep spindles, K-complexes, and positive occipital sharp transients?

Answer 12

Stage N2

Question 13

What asleep EEG stage is the slow wave sleep?

Answer 13

Stage N3

Question 14

What EEG stage is low voltage EEG, no muscle tone, and SAW TOOTH WAVES?

Answer 14

Stage REM

Question 15

In an abnormal EEG, what does focal slowing imply?

Answer 15

focal cerebral dysfunction

Question 16

In the abnormal EEG, what does generalized slowing imply?

Answer 16

diffuse cerebral dysfunction or deep dysfunction (thalamic or ARAS)

Question 17

What are the abnormal EEG forms of paroxysmal activity?

Answer 17

spikes, spike-wave (imply seizure tendency)

These can be focal or generalized

Question 18

In the US what percentages—

1. will have 1 seizure?
2. Will have Recurrent Seizures?
3. Lifetime risk?
4. Current active epilepsy?

Answer 18

1. 10%
2. 4%
3. 3%
4. 1%

Question 19

What is the dormant basket cell hypothesis?

Answer 19

Inhibitory interneuron feedback is lost and excitation is unopposed creating prolonged depolarization. A population of neurons experiences repetitive action potentials—->seizure

Question 20

What is the mossy fiber sprouting hypothesis?

Answer 20

mossy fibers synapse back on themselves producing a positive feedback loop and CA3 cells undergo sustained depolarization —-> seizure

Question 21

What do we see in the neocortical pyramidal cell and the TRN in absence seizure pathophysiology? what is recorded from cortex?

Answer 21

hyperexcitable cortex and thalamus produce and excessive reverberating loop

generalized spike wave is recorded

Question 22

What is the pathophysiology of the complex partial seizure?

Answer 22

abnormality of hippocampus with aberrant dendritic sprouting of excitatory neurons and loss of inhibitory

Question 23

What are the clinical signs of complex partial seizure?

Answer 23

staring, unresponsive, automatic movements, lasts 30-120 seconds

Question 24

What does the EEG look like in a complex partial seizure?

Answer 24

focal, rhythmic sharp activity

Question 25

What is the pathophysiology of an absence seizure?

Answer 25

genetic hyper excitability of the cortico-thalamic loop

Question 26

What are the clinical manifestations of an absence seizure?

Answer 26

no aura, staring, unresponsive, no post-octal confusion, lasts 5-15 seconds

Question 27

What does the EEG show for an absence seizure?

Answer 27

generalized 3 Hz spike wave

Question 28

What are the treatment strategies of partial seizures?

Answer 28

1. inhibit excitation
2. Promote Inhibition
3. Electrically modulate
   4 Surgical Resection

Question 29

What are the treatment strategies for generalized seizures?

Answer 29

1. inhibit excitation
2. Inhibit hyper polarization of intralaminar thalamic neurons [Ca antagonist]
3. Electrically modulate the circuit