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NSB > Seizures and Epilepsy > Flashcards

Seizures and Epilepsy Flashcards

1
Q

What is Epilepsy?

A
  • chronic condition of recurrent seizures
    that can also vary from brief and nearly
    undetectable symptoms to periods of
    vigorous shaking and convulsions
  • not a single disease
  • affects 0.5-1% of the population
  • 2 or more unprovoked seizures
    separated by 24 hours or 1 with a
    likelihood of reccurrence eg brain
    structure abnormality
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2
Q

What is a seizure?

A
  • temporary disruptions of brain
    function causes by uncontrolled
    synchronous, paroxysmal excessive
    neuronal activity manifesting as a
    stereotypes disturbance of
    consciousness, behaviour, emotion,
    motor function or sensation
  • usually lasting seconds to minutes

= abnormal excessive firing of the brain

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3
Q

Unprovoked Seizures are

A

caused by an unknown and reversible medical cause

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4
Q

Seizures: Features:

A
  • abnormal firing of the brain
  • focal seizures = localised
  • can become generalised = both
    hemispheres
  • if greater than 5 mins = status
    epilepticus
  • medical emergency, mortality is 10-
    15%
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5
Q

Focal vs Generalised Seizures:

A

insert table

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6
Q

What is it called when a seizure lasts longer than 5 mins?

A

Status epilepticus

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7
Q

What does a seizure look like?

A
  • not always convulsion
  • prodrome: feeling, sensations,
    changes in behaviour hours or days
    before event
  • preictal/aura: immediately prior (not
    always present)
  • icta: actual event
  • post-ictal: drowsy, confused, psychotic,
    bitten tongue, lost continence
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8
Q

Seizure: History of Events:

A
  • diurnal pattern
  • if more than one seizure:
    - max seizure free period?
    - seizure frequency?
    - hospitalisations?
    - falls and injuries
  • pre-natal and post-natal development?
  • history of febrile seizures
  • history of CNS (lesions, infections?)
  • history of brain trauma specifically
    associated with penetrating injuries
  • family history of epilepsy
  • social history: education, employment,
    driving status, drug and alcohol use
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9
Q

Seizures: Aetiology:

A
  • antenatal: infection, trauma, hypoxia
  • genetic
  • electrolyte disturbances
  • infections
  • drugs/meds
  • tumours
  • trauma
  • congenital disorders
  • neurodegenerative disorders

Adult: stroke, tumour, trauma, infection

Child: genetic/metabolic disorders,
trauma, infection

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9
Q

Seizure symptoms are related to the

A

location of abnormal firing

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10
Q

Seizure: Acute Symptomatic Management:

A
  • treat the underlying cause:
    • blood tests
    • lumbar puncture
    • imaging
  • benzodiazepines: can not be used
    prophylactically due to side effects,
    tolerance and dependance
    (used if going toward status epilepticus
  • antiseizure/ anti-convulsants
    medication if there is a
    high risk of recurrence/previous
    history of seizures
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11
Q

Which lobe has most abnormal firing?

A

temporal lobe
area of most neurogenesis

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12
Q

Provoked Seizures and Recurrence:

A
  • provoked immediate (toxin,
    medication, metabolic) = recurrence is
    low in absence of provoking factor
  • acute symptomatic (close to time of a
    brain insult) = recurrence is 80% less
    likely than a remote symptomatic
    seizure
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13
Q

Unprovoked Seizures:
- remote symptomatic
- associated with

A
  • remote symptomatic (pre-existing
    brain injury)
  • associated with an epileptic syndrome
  • unidentified
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14
Q

Seizure Differential Diagnosis:

A

insert table

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15
Q

What does EEG record?

A
  • result of many excitatory and
    inhibitory post synaptic potentials
    (large group of neurons active at the
    same time) at the level of the cortex
  • depends on the timing and orientation
    of neurons
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16
Q

The Eye and the EEG:

A
  • eye is electrically charged, positive
    cornea and negative retina
  • eyes roll up when eye is closed
  • repetitive blinking can look like a
    seizure as rhythmic movement
  • same as eating
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17
Q

EEG Utility For Seizures:

A
  • epileptic seizures will have
    epileptiform discharges on the EEG
    during and event
  • changes on EEG can also be seen
    between seizures = inter-ictal
    epileptiform discharges
  • the sooner an EEG can be obtained
    after a seizure, the more likely it will
    detect an IED within 72hrs
  • IED can be reduced by levetiracetam,
    valproate and acutely by diazepam
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18
Q

What does inter-ictal epileptiform discharges firing refer to?

A

abnormal firing of neurons picked up on EEG between seizures

19
Q

Normal EEG rules out epilepsy.

True or False?

A

False

a normal EEG during an event means the event was not epileptic

but a normal EEG after the event just means that abnormalities was not picked up

20
Q

What is the probability of recurrence in the next ten years after two unprovoked seizures?

A

60%

21
Q

A single seizure vs multiple in 24 hours confers no higher risk of recurrence.

True or False?

A

True

22
Q

Seizures: Acute Treatment:

A
  • most self-terminate within minutes
  • if a seizure continues then initially
    treated with benzodiazepine (quick
    acting)
  • longer a seizure persists the harder it
    is to control (internalisation of GABA
    receptors)
23
Q

The likelihood of having a second seizure after a first seizure is highest within the first two years.

True or False?

A

True

24
Q

When is neuronal death, injury and alteration to networks believed to occur in regards to seizures?

A

After a seizure that lasts 30 minutes

declared status epilepticus after 5 minutes

25
Q

Seizure Precautions:

A
  • avoid sleep deprivation, alcohol,
    infection
  • avoid unsupervised activities that pose
    danger with sudden loss of
    consciousness: baths, swimming,
    working at heights, heavy machinery
  • driving
  • neuropsychiatric co-morbidities
26
Q

What are the different phases of status epilepticus?

A

insert slide

27
Q

SUDEP is

A

sudden unexplained death of epilepsy

28
Q

SUDEP Features:

A
  • 2-18% of all deaths in epileptic patients
  • higher in children
  • unknown reason -> multifactorial
  • increases with severity of epilepsy
  • 10 fold higher risk in generalised
    seizures
  • higher in poorly controlled epilepsy
29
Q

Treating Seizures:

A
  • goal: complete seizure freedom with
    no side effects (tolerability)
  • around 50-60% of patients become
    seizure-free on a single drug
  • current drug therapy is effective in 70-
    80% of patients
  • 30-40% patients may not respond to
    medication (refractory)
    - rule out seizure imitators
    - evaluate possibility of surgically
    remediable syndromes
    - diet
    - devices (vagal nerve stimulator)
30
Q

Most antiepileptics with known mechanisms of action work by (3):

A
  • blocking excitation
  • increasing inhibition
  • prevent repetitive firing
31
Q

How does diazepam work as an anticonvulsant?

A

enhancing GABA action (absence seizures can be exacerbated by this mechanism of action)

32
Q

How does carbamezpine work as an anti-convulsant?

A

iincreases inhibition by inhibiting Na+ channel function

stop Na+ channel from working, prevent influx of Na+, hence prevents firing of action potential

33
Q

How does Gabapentin work as an anti-convulsant?

A
  • increasing inhibition
  • inhibition of Ca2+ channel
34
Q

How does sodium valproate work as ana anti-convulsant?

A

inhibits excessive excitation

  • enhancing GABA action?
  • inhibiting Na+ channel function **
  • inhibiting Ca2+ channel function
35
Q

Which of the following anticonvulsants are broad spectrum?

  • carbamazepine
  • phenytoin
  • gabapentin
  • diazepam
  • levetiracetam
  • sodium valproate
A
  • diazepam
  • levetiracetam
  • sodium valproate
36
Q

Which of the following anticonvulsants are narrow spectrum?

  • carbamazepine
  • phenytoin
  • gabapentin
  • diazepam
  • levetiracetam
  • sodium valproate
A
  • carbamazepine
  • phenytoin
  • gabapentin
37
Q

Broad Spectrum Anti-convulsants:

A

insert table

38
Q

Narrow Spectrum Anti-Convulsants:

A

insert table

39
Q

compare the IV and subcutaneous route of administration for drugs

A

IV = rapid, but doesnt last as long
Subcutaneous = slowly, but lingers

40
Q

Steady state:

A
  • steady state is reached in 5 half-lives (5
    doses)
  • steady state wanted for antiseizure
    medication
  • give a high loading dose when
    therapeutic range needs to be reached
    quickly
  • get the trough level for monitoring but
    do not hold drug if half life is short
41
Q

Complex pharmacokinetics: Phenytoin:

A
  • phenytoin is 90% protein bound
  • alterations in protein will impact the
    free concentration
  • phenytoin is metabolised in the liver
  • inter-individual difference in level of
    saturation
  • rate of elimination is therefore altered
    when metabolism is saturated
42
Q

Core Drug: Diazepam (anticonvulsant): Metabolism Considerations:

A

CP450

43
Q

Core Drug: Vaproate:

A
  • highly protein bound will compete with
    phenytoin
  • metabolised by the liver, excreted in
    urine
  • dose dependent teratogenicity
44
Q

Core Drug: Carbamazepine: Metabolism Considerationa:

A
  • metabolised into carbamazepine
    epoxide
  • potent inducer of CYP450
    (autoinduction)
  • interactions with lamotrigine, lithium,
    phenytoin, valproate
  • steady state reached in 20 days due to
    autoinduction
45
Q

Drug-Resistant Epilepsy:

A
  • failure of two tolerated and
    appropriately chosen anti-seizure
    meds
  • 30-40% ppl
  • surgery
  • neurostimulator devices
  • ketogenic diet
46
Q

Remission of Epilepsy:

A
  • 10 years seizure free with the last 5
    years of antiepileptic drugs
  • seizure recurrence rate after drug
    discontinuation = 35%
  • 3% may not regain seizure control
  • most recurrence occurs within 1 year
    of discontinuation
  • short durations of active disease,
    longer seizure free periods, ease of
    controlling seizures increases
    likelihood of success

NSB (50 decks)

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