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Brain and behaviour 2 > PBL 3: A difficult decision > Flashcards

PBL 3: A difficult decision Flashcards

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The Brain flashcards
1
Q

What is epilepsy?

A

An epileptic seizure is the clinical event that occurs when there is an excessive, sustained and synchronised electrical discharge in a network of neurones

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2
Q

What are the two categories of epilepsy?

A

Focal

Generalised

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3
Q

What are characteristics of focal epilepsy?

A

Seizures that arise from specific cortical region, spreading to other areas or not
Occurs at any age

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4
Q

What are characteristics of generalised epilepsy?

A

Seizures that do not seem to arise from a specific region
Manifestation of bilateral discharges that result from a fast synchronisation of cortical networks
Often starts at young age

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5
Q

What are the classification of partial seizures?

A

Simple partial
Complex partial
Partial seizure with secondary generalisation

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6
Q

What are the classification of generalised seizures?

A

Absence
Tonic-clonic
Statis epilepticus

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7
Q

What is a simple partial seizure?

A

When activity is limited to a focal area

No loss of consciousness

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8
Q

What happens in complex partial seizure?

A

Altered awareness
Semi autonomic movements (automatisms)
Associated with temporal structures

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9
Q

What happens in partial seizures with secondary generalisation?

A

Spread over cerebral cortex
Originates in non-eloquent part of brain
Spreads v quickly

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10
Q

What is an absence seizure?

A

Occurs in childhood
Possibly many times a day
Lasts 5s

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11
Q

What may a patient experience before a tonic-clonic seizure?

A

Aura

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12
Q

How long does the tonic phase last?

A

10-40s

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13
Q

What happens in tonic phase?

A

Patient becomes rigid as muscles undergo tonic, sustained contraction
Patient falls rigidly

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14
Q

Why may a grunt be heard in tonic phase?

A

respiratory + laryngeal muscles contract so grunt is heard as air leaves chest through taut vocal cords

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15
Q

What may happen to patient in tonic phase?

A

Cyanotic

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16
Q

What happens after clonic phase?

A

Coma period

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17
Q

What happens during clonic phase?

A

Muscles go into strong, rhythmic contractions

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18
Q

What accompanies limb jerking in clonic phase?

A

Urinary + faecal incontinence as well as tongue biting and frothing at mouth

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19
Q

Why is there tachycardia in clonic phase?

A

Breathing is jerky and inefficient

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20
Q

How long does clonic phase last?

A

2-3m

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21
Q

What is status epilepticus?

A

Seizure lasting 30m or more or recurrent seizures over the same time with incomplete recovery between them
MEDICAL EMERGENCY

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22
Q

What mutation can cause epilepsy?

A

Ion channels e.g. Na+, K+, Ca2+, GABAa

E.g. SCN1B mutation

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23
Q

Is there a genetic basis in epilepsy?

A

Yes

24
Q

What are the 3 main mechanisms by which anti epileptic drugs work?

A

Modulation of intrinsic membrane conductances
Primarily voltage gated cationic channels
Suppression of excitatory amino acid-mediated synaptic transmission

25
Q

What are the 3 states of sodium channels?

A

Depolarisation: closed
Closed/inactivated: spontaneously after depolarisation
Hyperpolarisation: resting and closed

26
Q

What drugs target sodium channels?

A

Carbamazepine
Phenytoin
Idea is to increase refractory period

27
Q

What are the types of calcium channels?

A

L
P/Q
N
T

28
Q

Which calcium channel requires less depolarisation to be activated?

A

T

29
Q

Which GABA is fast and slow?

A 
GABAa = fast
GABAb = slow
30
Q

What is GABAa permeable to?

A

Cl-

31
Q

What does opening og GABAa lead to?

A

Hyperpolarisation as Cl- is usually higher extracellularly than intracellularly

32
Q

Where is GABAb expressed?

A

Pre and post synaptically

33
Q

What does activation of GABAb do?

A

Inhibition of adenylyl cyclase
Voltage-gated Ca2+
Activation of inward K+ channels

34
Q

What do potassium channels do?

A

Repolarise neurons following action potentials

35
Q

What does phenytoin do to potassium channels?

A

Selectively block outward K+ channels so are rpo-convulsant

Repolarisation takes longer to occur

36
Q

What receptors do glutamate work on

A

Ionotropic e.g. NMDA, AMPA, kainite receptors

Metabotropic

37
Q

What are NMDA receptors permeable to?

A

Ca2+ and Na+ ions

38
Q

What are NMDA receptors extremely sensitive to?

A

Glutamate and may be activated by extra-synaptic glutamate if in high quantities (this is called spill over)

39
Q

Give an example of an NMDA receptor drug

A

Carbamazepine

40
Q

What are AMPA and Kainate receptors associated with?

A

Channels are that permeable to sodium ions

41
Q

Give examples of AMPA and Kainate receptor drugs

A

Topiramate/phenobarbitone (inhibits AMPA/kainite receptors)

42
Q

What is surgical options of the brain?

A

Resection of seizure onset zone in brain

Corpus callostomy

43
Q

When won’t drug treatment work?

A

If patient has failed 2 AEDs (patients with focal epilepsy will be referred)

44
Q

When is corpus callostomy used?

A

When patients have drop attacks/atonic seizures

45
Q

What are other non-pharmalogical treatments?

A

Vagus nerve stimulation

Ketogenic diet

46
Q

Which are the safest AEDs in pregnancy?

A

Carbamazepine

Lamotrigine

47
Q

What drug is not recommended in epilepsy?

A

Valproate

48
Q

How can pregnancy impact seizure frequency?

A

AED blood levels fall
Altered oestrogen and progesterone
Sleep deprivation

49
Q

What is main risk to baby?

A

Doesn’t receive oxygen

50
Q

Which calcium channels are expressed post synaptically?

A

T

51
Q

What are structural changes in epilepsy?

A

Reorganisation of the tissue in temporal lobe epilepsy
Sprouting of mossy fibres of granule cells
Neurogenesis
Chandelier cells

52
Q

What is a paroxysmal Depolarising shift?

A

Occurs in neurons with uncontrolled/sustained discharges occur
Membrane is depolarised by 30-40mV accompanied by burst of action potentials

53
Q

What causes a Paroxysmal depolarising shift?

A

Activation of the glutamate receptors of the NMDA type

54
Q

What is an important theory to why seizures occur?

A

Imbalance between excitatory (glutamate) and inhibitory (GABA) neurotransmitter systems

55
Q

What supports the theory of an imbalance in neurotransmitters?

A

o GABA antagonists and glutamate agonists are triggers for seizures.
o Drugs that encourage GABA transmission are antiepileptics.
o In prolonged seizures glutamate levels rise and GABA levels fall.
o Rise in CSG GABA are seen to correlate with action of antiepileptic Vigabatrin

Brain and behaviour 2 (27 decks)

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