Epilepsy Flashcards Preview

Year 2 C&M symposia > Epilepsy > Flashcards

Flashcards in Epilepsy Deck (83):
1

What is a seizure?

Excessive, hypersynchronous activity of neurons in the brain >> convulsions, thought disturbances, twitching.

2

How are seizures classified?

Based on location within the cerebral cortex.

3

What are the 3 main types of seizure?

-Generalised
-Partial
-Secondary generalised

4

What is a generalised seizure?

A seizure with initial activation neurons throughout both hemispheres.

5

What is a partial seizure?

A seizure with the initial activation of a limited number of neurons in a part of 1 hemisphere.

6

What is a secondary generalised seizure?

A partial seizure that later spreads to involve the majority of the 2 cerebral hemispheres.

7

What are the 3 subtypes of partial seizures?

-Simple
-Complex
-With 2* generalisation

8

What is a simple partial seizure?

Partial seizure activity while the person is alert.

9

What is a complex partial seizure?

Partial seizure activity with change of awareness of the surroundings.

10

What are the 5 subtypes of generalised seizures?

-Absence
-Myoclonic
-Tonic-clonic
-Tonic
-Atonic

11

What is characteristic of an absence generalised seizure?

Staring and blinking without falling.

12

What is characteristic of a myoclonic generalised seizure?

Jerking movements of the body.

13

What is characteristic of a tonic-clonic generalised seizure?

Stiffening, falling and jerking of the body.

14

What is characteristic of a tonic or atonic generalised seizure?

Falling heavily to the ground.

15

What is the manifestation of a partial seizure dependent on?

The site of origin in the brain.

16

How does a partial seizure originating in the anterior frontal lobe present?

Adversive seizures.
-eyes/head both turn to one side

17

How does a partial seizure originating in the posterior frontal lobe present?

Jacksonian seizure.
-tingling feeling in the hand or arm

18

How does a partial seizure originating in the parietal lobe present?

Tingling/jerking of leg, arm or face.

19

How does a partial seizure originating in the occipital lobe present?

-Flashing lights
-Spots
-Vomiting

20

How does a partial seizure originating in the temporal lobe present?

-Strange smell/taste
-Altered behaviour
-Deja vu
-Chewing movements

21

What is used to record electrical activity in the brain?

Electroencephalogram (EEG).

22

What type of waves does and EEG produce?

Spike-wave discharges.

23

How can you tell the difference between a partial and generalised seizure from an EEG?

-PARTIAL - excess activity only in electrodes from one hemisphere
-GENERALISED - excess activity in both hemispheres

24

What is status epilepticus (SE)?

Life threatening condition where brain is in a state of persistent seizures.

25

What are the 2 definitions of status epilepticus?

-More than 30 mins continuous seizure activity
-2+ sequential seizures spanning 30 mins without full recovery between seizures

26

What does status epilepticus increase the risk of?

Future unprovoked seizures.

27

What is epilepsy?

Condition in which seizures recur (2+), usually spontaneously.
-a single seizure is not considered as epilepsy

28

What are the 2 basic mechanism of seizures?

Excitation and inhibition.
-either can cause too much neuronal activity

29

How does excitation of neurons occur?

-IONIC (Na/Ca influx)
-NEUROTRANSMITTER (glutamate/aspartate release)

30

How does inhibition of neurons occur?

-IONIC (Cl/K efflux)
-NEUROTRANSMITTER (GABA release)

31

What group of brain cells are responsible for allowing activity to spread in one direction?

Inhibitory interneurons.

32

What do inhibitory interneurons release?

GABA.
-neurotransmitter

33

What does GABA stand for?

Gamma-aminobutyric acid.

34

What are the 2 types of GABA recpetor?

-GABAa receptors
-GABAb receptors

35

What are GABAa receptors?

Ligand-gated chloride channel receptors.

36

What are GABAb receptors?

G protein-coupled receptors.

37

What structure do GABAa receptors have?

Pentameric structure.
-2a, 2b, 1g/o.

38

What do the subunits of GABA receptors determine?

Intrinsic properties.
-e.g. affinity for diazepam

39

Name 4 epilepsies caused by GABAa receptor mutations.

-Childhood absence epilepsy
-Febrile seizures
-Juvenile myoclonic epilepsy
-Dravet syndrome

40

What can a GABRG2(Q390X) nonsense mutation in a GABAa receptor lead to?

DRAVET SYNDROME.
-loss of 78 C-terminal AAs >> more hydrophilic surface
-receptor becomes cytosolic protein, not transmembrane

41

What is Dravet syndrome also known as?

Severe myoclonic epilepsy in infancy.
-variety of seizures in 1st year of life

42

Give an example of a drug that can be used on animals to induce status epilepticus.

PILOCARPINE.
-proconconvulsant drug
-non-selective muscarainic receptor agonist

43

How does status epilepticus alter GABAa receptor composition in the mice tested?

Alters the abundance of subunits in dentate granule cells (hippocampus).
-Decreases a1, increases a4.

44

What is a feature of a4 subunits in GABA receptors?

Desensitise rapidly.
-especially when with b3

45

What effect does increasing a1 subunits have?

-Increased latency time
-Decreased rate of seizure development
-Fewer spontaneous seizures

46

What is the purpose of anti-epileptic drugs?

Decrease the frequency/severity of seizures.
-treat the symptoms of seizures, don't cure

47

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

-Suppress action potentials
-Enhance GABA transmission
-Suppress excitatory transmission

48

How do anti-epileptic drugs suppress action potentials?

-Sodium channel blocker
-Potassium channel opener

49

How do anti-epileptic drugs enhance GABA transmission?

-GABA uptake inhibitor
-GABA mimetics

50

How do anti-epileptic drugs suppress excitatory transmission?

-Glutamate receptor antagonists

51

What is the type of anti-epileptic drug dependent on?

The type of seizure.

52

What is the most widely used anti-epileptic drug?

Valproic acid.

53

What seizure types are treated by the following:
-Carbamazepine
-Phenytoin
-Valproic acid

-Partial simple
-Partial complex
-Generalised tonic clonic

54

What seizure type is treated by the following:
-Ethosuximide
-Valproic acid

Absence seizure.

55

What seizure types are treated by the following:
-Valproic acid

-Atypical absence
-Atonic, myoclonic

56

What seizure type is treated by the following:
-Diazepam
-Rectal

Febrile seizures.
-child with a fever

57

What are the methods of enhancing GABA action?

-Enhance action of GABAa receptors (barbiturates/benzodiazepines)
-Inhibit GABA transaminase (vigabatrin)
-Inhibit GABA uptake (tiagabine)

58

Give an example of a barbiturate.

Phenobarbital.

59

Give an example of a benzodiazepine.

Clonazepam.

60

How do benzodiazepines work?

Increase GABA affinity >> suppresses seizures.
-Increase CL current
-Raise AP
-Strengthens surround inhibition

61

What are possible side effect of benzodiazepines?

-Sedation
-Respiratory depression (IV)

62

What is diazepam (valium) used to treat?

Status epilepticus.
-IV

63

Which anti-epileptic drugs act by inhibiting Na+ channels? (3)

-Phenytoin
-Carbamazepine
-Lamotigine

64

What is the mechanism of action of phenytoin?

Binds to inactivated Na+ channels >> slows down repolarisation.

65

What anti-epileptic drugs have mixed actions?

-Gabapentin
-Valproate
-Levetiracetam

66

What is meant by mixed action?

Combination of the following:
-Enchance GABA transmission
-Inhibit Na+ channels
-Inhibit NT release

67

Which drug is not chemically related to other anti-epileptics?

Valproate.

68

How is valproate unusual?

Acts against both tonic-clonic and absence seizures.

69

What are the mechanisms of valproate? (3)

-Inhibits Na+ channels
-Decreases GABA turnover
-Blocks neurotransmitter release

70

What is the problem with pregnancy?

Drugs may harm baby, but seizures may also cause harm.

71

What is recommended during pregnancy?

-Folic acid
-Monotherapy (rather than drug combination)

72

Which drugs are absolutely contraindicated during pregnancy? (AVOID)

-Phenytoin
-Valproic acid

73

What causes foetal hydantoin syndrome?

Mother taking phenytoin during pregnancy (30%).

74

What are the symptoms of foetal hydantoin syndrome? (4)

-Growth restriction and microcephaly
-Dysmorphic craniofacial features
-Limb defects
-Developmental defect

75

What causes foetal valproate syndrome?

Mother taking valproate during pregnancy (6-9%).

76

What proportion of epileptics are seizure free with one drug?

70%.

77

What proportion of epileptics are seizure free with 2+ drugs?

5-10%.

78

What proportion of epileptics still have seizures with anti-epileptic drugs?

20%.
-Refractory epilepsy

79

What is the mechanism of optogenetics?

Halorhodopsins (Cl- channels) are activated by yellow light >> open and allow Cl- to enter.

80

What can optogenetics do?

Suppress seizures with epilepsy.

81

What could optogenetics be used to control?

Epilepsia partialis.

82

What is epilepsia partialis continua?

Rare brain disorder >> recurrent motor epileptic seizures that are focal (hands and face).

83

What normally causes epilepsia partialis?

-Large, acute brain lesions due to strokes
-Focal cortical inflammatory processes (children)