Epilepsy Flashcards

1
Q

What is a seizure?

A

The clinical manifestation of an abnormally excessive and hypersynchronous activity of neurones

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2
Q

Where does the abnormal activity of neurones predominantly occur in seizures?

A

cerebral cortex

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3
Q

Describe a generalised seizure

A

initial activation of neurones throughout both hemispheres

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4
Q

Describe a partial seizure

A

initial activation of a limited number of neurones in a part of 1 hemisphere

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5
Q

Describe a secondary generalised seizure

A

a partial seizure hat later spreads to involve the majority of 2 cerebral hemispheres

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6
Q

What type of motion does the term ‘myoclonic’ describe?

A

jerking movements of the body

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7
Q

What type of motion does the term ‘tonic-clonic’ describe?

A

stiffening, falling and jerking or the body

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8
Q

What would you see in someone having an absence seizure?

A

staring and blinking without falling

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9
Q

What motion would you see in someone having a secondary generalised seizure?

A

seizure activity begins in one area then spreads

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10
Q

What would see in someone having a simple partial seizure?

A

seizure activity while the person is fully alert

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11
Q

How would a partial seizure of the frontal lobe manifest?

A
Jacksonian seizure (tingling feeling in hand or arm) OR 
adversive seizures (eyes or head both turn to one side)
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12
Q

How would a partial seizure of the parietal lobe manifest?

A

tingling in or jerking of leg, arm, face

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13
Q

How would a partial seizure of the occipital lobe manifest?

A

flashing lights of spots, vomiting

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14
Q

How would a partial seizure of the temporal lobe manifest?

A

strange smell or taste and altered behaviour

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15
Q

How does an EEG work?

A

uses scalp electrodes to record the electrical activity along the scalp produced by the firing of neurones within the brain

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16
Q

What is status epilepticus?

A

a life-threatening condition in which the brain is in a state of persistent seizure (more the 30 mins continuous seizure OR two or more sequential seizures spanning this period without full recovery between them)

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17
Q

How would you intervene in status epilepticus?

A

injection of GABAa receptor agonist and diazopan

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18
Q

What is epilepsy?

A

a condition in which seizures recur, usually spontaneously

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19
Q

What happens in ionic excitation?

A

Na+ and Ca2+ influx

20
Q

What happens in neurotransmitter excitation?

A

glutamate and aspartate release

21
Q

what happens in ionic inhibition?

A

Cl- influx and K+ efflux

22
Q

What happens in neurotransmitter inhibition?

A

GABA release

23
Q

What is the function of inhibitory interneurons?

A

allow activity to spread in one direction, but not to spread out sideways

24
Q

What do inhibitory interneurons release to carry out their function?

A

GABA (inhibitory neurotransmitter)

25
Q

What percentage of neurones in the brain are interneurons?

A

10-20%

26
Q

What is the structure of GABAa receptors?

A

ligand-gated chloride channel receptor

27
Q

What is the structure of GABAb receptors?

A

G protein-coupled receptor

28
Q

How many subunits make up a GABAa receptor?

A

5 (2 alpha, 2 beta and either 1 gamma or 1 delta)

29
Q

Which types of epilepsy are known to be caused by mutations in GABAa receptor subunits? (5)

A

CAE, FS, GEFS+, JEM, DS

30
Q

What change in structure does the gamma2 (Q390X) nonsense mutation cause?

A

truncated subunit with the loss of 78 C-terminal amino acids

31
Q

What is SUDEP?

A

sudden death in epilepsy

32
Q

What is the action of pilocarpine?

A

a non-selective muscarinic receptor agonist used to induce an episode of self-sustained SE in previously healthy animals

33
Q

What are the 3 main modes of action of anti-epileptic drugs?

A
  • suppress action potential
  • enhance GABA transmission
  • suppression of excitatory transmission
34
Q

How can AEDs suppress action potentials?

A
  • sodium channel blocker or modulators

- potassium channel openers

35
Q

How can AEDs enhance GABA transmission?

A
  • GABA uptake inhibitors

- GABA mimetics

36
Q

How can AEDS suppress excitatory transmission?

A

glutamate receptor agonist

37
Q

How do anticonvulsnats act?

A
  • enhancement of GABAergic transmission
  • inhibtioin of Na+ channels
  • mixed actions
38
Q

How can we enhance GABAergic transmission?

A

Enhance action of -GABAA receptors with barbiturates e.g. phenobarbital

  • Enhance action of GABAA receptors with benzodiazepines e.g. clonazepam
  • Inhibit GABA transaminase - vigabatrin
  • Inhibit GABA uptake - tiagabine
39
Q

What is clonazepam used for?

A

effective in generalised tonic-clonic absence and partial seizures

40
Q

What is clorazepate used for?

A

effective against partial seziures (used in conjunction with other drugs)

41
Q

Wha is the mechanism of action of benzodiazepines?

A

increased affinity of GABA for its receptor (increased Cl- current, suppresses seizure focus by raising action potential threshold, strengthens surround inhibition)

42
Q

Which are the main drugs used for inhibition of Na+ channels?

A
  • phenytoin
  • carbamazepine and oxcarbamazepine
  • lamotrigine
43
Q

How is valproate unusual?

A

effective against both tonic-clonic and absence

44
Q

What are the mechanisms of action of valproate?

A
  • inhibits Na+ channels
  • decreased GABA turnover
  • blocks neurotransmitter release by blocking T-type Ca2+ channels
45
Q

How can foetuses of mothers taking phenytoin be effected?

A

foetal hydantoin syndrome

46
Q

What is epilepsia partialis continua?

A

condition with recurrent motor epileptic seizures that are focal (hands and face), recur every few seconds for extended periods