Epilepsy/Seizures

Question 1

the clinical manifestation of an abnormal and excessive excitation and synchronization of a population of cortical neurons

Answer 1

seizure

Question 2

a tendency toward recurrent seizures UNPROVOKED by any systemic or acute neurologic insults

Answer 2

epilepsy

Question 3

sequence of events that converts a normal neuronal network into a hyperexcitable network

Answer 3

epileptogenesis

Question 4

Principal or pyramidal neurons form what type of synapse?

Answer 4

excitatory synapse on post-synaptic neurons

Question 5

Interneurons or basket cells form what type of synapse?

Answer 5

inhibitory synapse on principal cells or other inhibitory neurons

Question 6

When does recurrent inhibition occur?

Answer 6

when a principal neuron forms synapses on an inhibitory neuron, which in turn forms synapses back on the principal cells to achieve a negative feedback loop

Question 7

excitatory NTs?

Answer 7

GLUTAMATE and aspartate

Question 8

inhibitory NTs?

Answer 8

GABA and glycine

Question 9

Describe the ionotropic glutamate receptor.

Answer 9

fast synaptic transmission; NMDA, AMPA, and kainate; Gated Ca2+ and gated Na+ channels

Question 10

Describe the metabotropic glutamate receptor?

Answer 10

slow synaptic transmission; quisqualate; regulation of second messengers (cAMP and inositol); modulation of synaptic activity

Question 11

Modulation of glutamate receptors

Answer 11

glycine, polyamine sites, zinc, redox site

Question 12

Describe GABA-A receptor.

Answer 12

post-synaptic, specific recognition sites, linked to Cl- channel, mediate

Question 13

Describe GABA-B receptor.

Answer 13

presynaptic autoreceptors, mediated by K+ currents, prolong activation of K+ channels

Question 14

What is burst firing?

Answer 14

firing very rapidly in “bursts,” results from repetitive activation of action potentials

Question 15

Where does burst firing frequently occur?

Answer 15

HIPPOCAMPUS (very important in seizure pathology bc lots of seizures generated here)

Question 16

Where do recurrent excitatory pathways occur?

Answer 16

in the hippocampus and neocortex via pyramidal collateralls

Question 17

What do recurrent excitatory pathways do?

Answer 17

promote spread of the seizure discharge

Question 18

Describe hippocampal sclerosis

Answer 18

common in temporal lobe epilepsy; good reason for surgery; results from having many seizures over time

Question 19

What is facilitation?

Answer 19

increased glutamate release

Question 20

What is potentiation?

Answer 20

enhanced synaptic activity

Question 21

High frequency repetitive firing results in…?

Answer 21

results in increased accumulation of Ca2+ near the presynaptic terminal and results in facilitation and potentiation; it also depresses inhibitory synaptic activity

Question 22

in areas with densely packed neurons (i.e.. hippocampus), how do neurons directly interact?

Answer 22

gap junctions; emphatic transmission due to close apposition of membranes allowing direct propagation of the seizure discharge

Question 23

List the 8 cellular mechanisms of epilepsy. (*important)

Answer 23

1 modification or alteration of ion channels; 2 synaptic reorganization and modification; 3 modulation of gene expression; 4 burst firing; 5 recurrent excitatory connections; 6 synaptic enhancement resulting in facilitation and potentiation produced by rapid firing; 7 depression of inhibitory synapses by high frequency firing; 8 non synaptic spread of electrical activity

Question 24

When can an acute seizure turn into epilepsy?

Answer 24

if an acute seizure is the result of trauma, and later that develops scaring, you can develop epilepsy bc of the pathway created

Question 25

What are spike and sharp waves?

Answer 25

spikes (

Question 26

are spike and sharp waves generalized, focal or both?

Answer 26

there are generalized and focal spike waves; and just focal sharp waves

Question 27

myoclonic seizure?

Answer 27

very fast jerk seizure

Question 28

atonic seizure?

Answer 28

they just fall. (walk around normal and then just fall and bust lip or something)

Question 29

convulsive seizure?

Answer 29

the kind you see on TV. different terms to describe how they move (tonic, clonic, tonic-clonic, clonic-tonic-clonic)

Question 30

absence seizure?

Answer 30

starring gaze (a lot of school teachers refer kids for this)

Question 31

focal seizure?

Answer 31

means originating in a particular part of the brain and staying in networks in that one hemisphere; if a focal seizure goes long enough it can generalize

Question 32

Generalized seizures?

Answer 32

conceptualized as originating at some point within and rapidly engaging bilaterally distributed networks

Question 33

Describe focal seizures at different levels of impairment.

Answer 33

1) w/o impairment of consciousness or awareness, with observable motor or autonomic components (old term: simple partial); 2) with impairment of consciousness or awareness (old term: complex partial); 3) evolving to bilateral, convulsive seizures [involving tonic, clonic, or tonic and clonic components] (old term: secondarily generalized)

Question 34

West syndrome (infantile spasms)*

Answer 34

these come in clusters after the baby is startled. kids w/ brain injuries are more likely to have these (shaken baby syndrome; cerebellar palsy; etc) but they don’t have to. flexion or extension spasms, cryptogenic vs. symptomatic, onset = birth - 2 years, 80% develop mental retardation, 60-70% have lifelong epilepsy, hypsarrhythmia pattern on EEG

Question 35

Atonic seizure description

Answer 35

no warning, abrupt onset; injuries common; very difficult to treat; may respond well to VNS (vagal nerve stimulator); corpus callosotomy may prevent falls

Question 36

Lennox-Gastaut syndrome

Answer 36

onset in early childhood; many underlying etiologies, often cryptogenic; MULTIPLE SEIZURE TYPES including atypical absence, generalized convulsive, atonic, myoclonic, partial; negative neurodevelopment impact – mental retardation; slow spike and wave (2 hertz)

Question 37

Focal seizure (parietal) – example

Answer 37

ex: keeps saying “okay okay…” to try to calm himself down bc has some feeling of being not right. he was having recurrent episodes of sudden fear or panic that increased in frequency. during these he maintained consciousness

Question 38

Focal seizure (frontal)

Answer 38

harder to diagnose; stereotypically it is exactly the same every time; does not look like a normal seizure; most commonly diagnosed pseudoseizure they see

Question 39

Focal seizure without impairment of consciousness (simple partial)

Answer 39

focal onset; aura is common; clinical manifestation is typically based on cerebral location of origin (i.e. frontal lobe – motor, parietal lobe – sensory, occipital lobe – vision); may secondarily generalize

Question 40

Focal seizure (temporal)

Answer 40

vocalization stuff is very common

Question 41

focal seizure with impairment of consciousness (complex partial)

Answer 41

aura is common, represents the ictal onset, stereotypical but may be difficult to describe; alteration of consciousness; automatisms (ex: fumbling w/ the sheets); postictal confusion; may secondarily generalize. if this lasts several minutes they are usually very confused

Question 42

Benign epilepsies of childhood*

Answer 42

centrotemporal or occipital spikes (benign epilepsy with centrotemporal spikes BECTS; panayiotopoulos syndrome or benign epilepsy w/ occipital spikes); nocturnal seizures are common; seizures are usually infrequent; remits by 15-16 years of age or earlier

Question 43

Absence description

Answer 43

brief stare with unresponsiveness; may have associated eye flutter (eyelid myoclonia); sudden onset with arrest of activity; no aura or postictal confusion; generalized 3 per second spike and wave; childhood absence – typical onset 5-9 years of age; juvenile absence – onset during early adolescence. usually noticed by the family, pt may have no idea.

Question 44

generalized tonic-clonic (and other generalized convulsive types)

Answer 44

no warning, abrupt onset; tonic, clonic, tonic-clonic or clonic-tonic-clonic activity; bowel and bladder incontinence common; postictal unresponsiveness or confusion; generalized spike and wave.

Question 45

Myoclonic seizure*

Answer 45

SUDDEN SINGLE JERKS of the arms and head; single or in clusters; no alterations in consciousness; may progress to clonic-tonic-clonic seizure; generalized multispike wave

Question 46

juvenile myoclonic epilepsy (JME)

Answer 46

MYOCLONIC SEIZURES with onset in late childhood or adolescence; may develop generalized convulsive (80%) or absence seizures (30%); autosomal dominant inheritance pattern, but many may represent new mutations with no family history

Question 47

What are some of the epilepsy surgeries performed?

Answer 47

temporal lobectomy, extratemporal lesional resection, extratemporal non-lesional resection, functional hemispherectomy; corpus callosotomy (especially for atonic and brief tonic seizures)