Seizures

Question 1

what is a seizure?

Answer 1

an episode of inappropriate electrical discharge resulting in disordered brain activity

Question 2

what is epilepsy?

Answer 2

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

Question 3

what is glutamate?

Answer 3

an excitatory neurotransmitter found throughout the nervous system

Question 4

what is GABA?

Answer 4

an inhibitory neurotransmitter found throughout the nervous system

Question 5

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

Answer 5

Question 6

what does ‘focal’ mean in terms of seizures?

Answer 6

a specific area of the brain

Question 7

what does ‘generalized’ mean in terms of seizures?

Answer 7

affecting both hemispheres

Question 8

what does the term ‘motor abnormalities’ refer to?

Answer 8

movement

Question 9

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

Answer 9

sensory and cognition

Question 10

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

Answer 10

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

Question 11

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

Answer 11

resting membrane potential = -70

threshold potential = -60

Question 12

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

Answer 12

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.

Question 13

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

Answer 13

oxygen and glucose

Question 14

why does trauma lead to seizures?

Answer 14

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

Question 15

why do toxins often lead to seizures?

Answer 15

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

Question 16

how does midazolam work to treat seizures?

Answer 16

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

Question 17

what is an aura?

Answer 17

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.

Question 18

what does catatonic mean?

Answer 18

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

Question 19

what does ‘tonic’ mean?

Answer 19

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

Question 20

what does ‘clonic’ mean?

Answer 20

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

Question 21

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

Answer 21

generalized

Question 22

what does ‘tonic-clonic’ mean?

Answer 22

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

Question 23

what does ‘atonic’ mean?

Answer 23

flaccid muscles

Question 24

what does ‘myoclonic’ mean?

Answer 24

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

Question 25

what is the post-ictal phase?

Answer 25

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)

Question 26

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

Answer 26

a blood glucose level

Question 27

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

Answer 27

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.)

Question 28

how is status epilepticus classified?

Answer 28

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

Question 29

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?

Answer 29

calcium

Question 30

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

Answer 30

glutamate

Question 31

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

Answer 31

sodium

Question 32

which ion moves out of the cell to begin repolarisation?

Answer 32

potassium

Question 33

what is levetiracetam?

Answer 33

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

Question 34

when is midazolam given on road?

Answer 34

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

Question 35

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

Answer 35

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

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