Seizures Flashcards

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1
Q

what is a seizure?

A

an episode of inappropriate electrical discharge resulting in disordered brain activity

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2
Q

what is epilepsy?

A

a condition in which there are repetitive but largely unpredictable episodes of seizure activity

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3
Q

what is glutamate?

A

an excitatory neurotransmitter found throughout the nervous system

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4
Q

what is GABA?

A

an inhibitory neurotransmitter found throughout the nervous system

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5
Q

explain the processes involved in the normal action potential of a neuron

A
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6
Q

what does ‘focal’ mean in terms of seizures?

A

a specific area of the brain

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7
Q

what does ‘generalized’ mean in terms of seizures?

A

affecting both hemispheres

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8
Q

what does the term ‘motor abnormalities’ refer to?

A

movement

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9
Q

what does ‘non-motor abnormalities’ refer to in regards to siezures?

A

sensory and cognition

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10
Q

explain the typical events that occur at a synapse during a seizure

A

innapropriate depolarisation > triggers calcium channels to open > influx of calcium at axon terminal > releases neurotransmitter contained in vessicle into the synapse > neurotransmitters in synapse bind to appropriate receptors on postsynaptic membrane > cause action potential in next neuron > process repeats in disorganised manner > causes disorganised brain function of some description

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11
Q

what is the normal resting membrane potential and threshold potential of a neuron?

A

resting membrane potential = -70

threshold potential = -60

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12
Q

how can a malfunctioning sodium-potassium (Na/K) pump lead to seizures activity?

A

The Na/K pump is essentially responsible for ‘cleaning up’ excess ions and returning a cell to its resting membrane potential (RMP). If it is malfuncitoning (hypoglycaemia/hypoxia/structural damage) it may not effectively balance the positive and negative ions. If this occurs and the RMP is more positive than it normally is, e.g. if it sits at -62 then only a small amount of stimulation will cause the cell to reach the thresholod potential and propogate an action potential.

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13
Q

what are the two things that are primarily going to imact the appropriate functioning of the Na/K pump?

A

oxygen and glucose

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14
Q

why does trauma lead to seizures?

A

trauma often leads to damage of cells and impacts the integrity of the cell membrane, meaning ions are able to pass across thr membrane innapropriately and cause action potentials to occur

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15
Q

why do toxins often lead to seizures?

A

toxins can impact the integrity of cell membranes, damage receptors, etc. Essentially impacts permeability of cell and makes it easier for ions to pass across the membrane innapropriately

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16
Q

how does midazolam work to treat seizures?

A

midaz acts on GABA receptor > receptor opens and allow negatively charged Cl ion to enter the cell > reduces the resting membrane potential of the cell (hyperpolerizes the cell) > makes it harder for the cell to be polarized

17
Q

what is an aura?

A

essentially just a strange sensation that some people get before having a seizure. It can manifest in many ways e.g. a strange taste in the mouth, slightly disturbed vision, a smell, etc.

18
Q

what does catatonic mean?

A

unconcious/dissociation - no stimuli coming in e.g. an absent seizure

19
Q

what does ‘tonic’ mean?

A

muscle stiffness (motor NS) - often seen in a tonic clonic seizure

20
Q

what does ‘clonic’ mean?

A

disordered jerky movements (motor NS) - e.g. in tonic clonic seizure

21
Q

are you more likely to be unconcious in a focal or generalized seizure?

A

generalized

22
Q

what does ‘tonic-clonic’ mean?

A

a relaxed muscle phase followed by a contract muscle cycle (motor NS)

23
Q

what does ‘atonic’ mean?

A

flaccid muscles

24
Q

what does ‘myoclonic’ mean?

A

isolated jerky movements (e.g. in one arm or leg, motor dysfunction)

25
Q

what is the post-ictal phase?

A

the period after a seizure has occured where a persons GCS is returning to normal - key features include confusion, abnormal engagement with environment, abnormal motor function, unusual behaviour (e.g. some people become unusually aggressive)

26
Q

what is one observation the is vital to obtain ASAP when attending a patient who is seizing?

A

a blood glucose level

27
Q

What are some of the most improtant questions to ask when identifying a seizure on road?

A

onset - what time did it start?

type - motor, psych, sensory changes were visible

end - when did the seizure stop (and phases e.g. tonic clonic to post ictal) (concerned about O2, blood, and glucose to the brain)

postictal - did the patient regain their normal GCS completely after the seizure

trigger/cause - known epileptic, is this a typical seizure for this person,

  • what has been different over the last few days (drinking more or less, drugs, medications, stress, symptoms)
  • what were they doing prior to the seizure (could identify hypoxic cause, trauma, etc.)
28
Q

how is status epilepticus classified?

A

a seizure the lasts longer then 5 minutes or having more than one seizure within a 5 minute period without returning to a normal conciousness between episodes

if they dont return to normal between seizures it is considered status in SAAS

29
Q

at the pre-synaptic terminal, what ion is allowed to move into the cell to trigger the release of the vesicles containing the excititory neurotransmitters?

A

calcium

30
Q

what is the predominate excititory neurotransmitter that is released from vesicles at the synapse? (relating to seizures)

A

glutamate

31
Q

along the axon which ion moves into the cell to propogate the action potential?

A

sodium

32
Q

which ion moves out of the cell to begin repolarisation?

A

potassium

33
Q

what is levetiracetam?

A

an antogaonist to glutamate release (vesicles) - common anti-epileptic drug (if glutamate can’t be released it can’t bind to the postsynaptic vesicle and cause an action potential

also known as kepra and is used on road as second line defense if benzodiazepines aren’t working

34
Q

when is midazolam given on road?

A

when a patient is having a seizure and there is a risk of injury

35
Q

Describe the electrical changes that contribute to a neuron’s hyperexcitable state

A
  • susceptible neurons have a resting membrane potentnial much closer to the threshold potential

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