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neurology/psychiatry > seizures > Flashcards

seizures Flashcards

1
Q

what is the definition of a seizure

A

a SYMPTOM of disturbed electrical activity in the brain

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2
Q

what is the bimodal distribution of first seizure occurrence

A

newborn infants & young children; patients >65 years

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3
Q

what is epilepsy

A

a chronic disorder of recurrent, unprovoked seizures

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4
Q

what are some characteristics that increase seizure risk

A

genetic mutations
patient with cerebral palsy, head injury, stroke, etc
MEDICATIONS
hormonal changes in pregnancy, etc

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5
Q

what medications increase seizure risk

A

-subtherapeutic AED levels
-withdrawal CNS depressants (alcohol, benzos, opioids, barbiturates, baclofen)
-antibiotics: PCN, cephs, cipro, carbapenems
-others (bupropion, SSRI, TCA overdose, etc etc)

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6
Q

what are some classifications of seizures

A

partial (focal): begins in one hemisphere & results in asymmetric motor manifestation
generalized: clinical manifestations that indicate involvement of both hemispheres
idiopathic: no identifiable cause; presumably genetic
secondary: infection, fever, intracranial event, toxin, metabolic

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7
Q

describe partial (focal) seizures

A

may manifest as changes in motor function, sensory symptoms, automatisms (sets of brief unconscious behaviors like lip smacking)
simple partial seizure: without loss of consciousness
complex partial seizure: with loss of consciousness

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8
Q

describe generalized seizures

A

bilaterally symmetrical without local onset
loss of consciousness
6 types: absence, myoclonic, clonic, tonic, tonic-clonic, atonic

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9
Q

describe what the different types of generalized seizures look like

A

absence: interruption of activities; blank stare (young kids)
myoclonic: brief shock-like contractions
clonic: rhythmic contractions
tonic: contract into rigid position
tonic-clonic: contraction followed by rigidity (patient may moan, cry, bite tongue, cyanosis)
atonic: sudden loss of muscle tone (head drop, limb drop, slumps to ground)– wear protective head gear

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10
Q

T/F: febrile seizures require daily antiepileptic therapy

A

FALSE

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11
Q

clinical pearls for TBI

A

early seizures occur within 7 days of TBI (late seizures represent epilepsy)
more severe injury is higher risk for late seizures
prophylaxis with antiepileptic drugs is used to prevent early post-traumatic seizures

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12
Q

who should be treated with AEDs?

A

not usually after the first seizure
start after the second seizure generally
also treat when patients present with status epilepticus or multiple seizures within a single day

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13
Q

how to discontinue AEDs?

A

may be considered by a neurologist after 2-4 years seizure free
gradual tapering reduces risk of provoking a seizure: taper at 25% of the dose monthly

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14
Q

considerations for seizures in the elderly population

A

think about drug interactions: many AEDs are CYP3A4 inducers/inhibitors
hypoalbuminemia is common in the elderly: some AEDs are bound to albumin which makes monitoring difficult
body mass changes, renal function, etc

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15
Q

considerations for seizures in the neonate/infant population

A

increased ratio of total body water to fat
decrease in albumin
newborns: decreased renal elimination/hepatic function
past 2-3 years: greater hepatic activity than adults so require higher AED doses

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16
Q

considerations for seizures in females

A

estrogen is seizure activating; progesterone is seizure protecting
high seizure vulnerability before/during period, at ovulation
peri-menopausal period can be associated with worsening seizure

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17
Q

considerations for seizures in pregnancy

A

25% of women have increased seizures during pregnancy

congenital malformation thought to be due to folate insufficiency associated with AEDs: prevent with adequate folate intake

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18
Q

considerations for hormonal contraception and seizures

A

women taking enzyme-inducing AEDs should use an alternative method of contraception
often recommend a preparation with at least 50 mcg estrogen

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19
Q

which of the big 4 older AEDs are inhibitors/inducers

A

inducers: carbamazepine, phenytoin, phenobarbital
inhibitor: valproic acid

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20
Q

what are the advantages of the newer AEDs

A

lower side effects, little or no need for serum monitoring, once or twice daily dosing for some, fewer drug interactions, all are pregnancy category C (vs D for older)

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21
Q

what is the FDA alert about AEDs

A

increased suicidality

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22
Q

phenytoin dosing

A

loading: 15-20 mg/kg IV at rate <50 mg/min (or <25 mg/min in hemodynamic instability) or 20 mg/kg PO divided by 3 and administered q2-4h

maintenance: 5-6 mg/kg/day in 1-2 divided doses

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23
Q

therapeutic range for phenytoin

A

trough 10-20 mg/L
Free 1-2 mg/L

obtained 2-3 weeks after initiation or change of dose

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24
Q

maintenance dosage increase ranges for phenytoin

A

increase by 100 mg/day if phenytoin <7
increase by 50 mg/day if phenytoin 7-12
increase by 30 mg/day if phenytoin >12

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25
Q

extra phenytoin loading dose to achieve desired serum levels

A

IV dose (mg/kg)= (Cdesired-Cactual) x 0.7
PO dose add extra 10%

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26
Q

correction for hypoalbuminemia

A

C corrected= C observed/[0.2(alb + 0.1)]

27
Q

correction for renal failure CrCL<10

A

C corrected= C observed/[0.1(alb + 0.1)]

28
Q

side effects of phenytoin

A

concentration dependent: lethargy, fatigue, blurred vision, dizzy, etc

independent: hypertrichosis, gingival hypertrophy, thickening of facial features, osteomalacia, folate deficiency, hypersensitivity

purple glove syndrome w/ IV

29
Q

pharmacokinetic considerations for phenytoin

A

hold tube feeds 1-2 hours before & after phenytoin administration. can’t substitute– different salt products are not the same.

90% bound to albumin (free phenytoin causes therapeutic effect) so low albumin increases free drug conc.

obesity increases Vd; use AdjBW if obese

30
Q

carbamazepine dosing

A

start at 200 mg BID
weekly increase by 200 mg/day
usual dose is 800-1200 mg/day given in 2-4 divided doses

31
Q

carbamazepine therapeutic range

A

4-12

32
Q

carbamazepine side effects

A

concentration dependent: nystagmus, ataxia, blurred vision, diplopia, vomiting, sedation, dizziness

independent: leukopenia: hold drug if WBC<2500 and ANC<1000

33
Q

serious clinical pearl for carbamazepine

A

do not treat patients with carbamazepine if they test positive for HLA-B*1502 allele (present in patients with Asian ancestry): strong correlation with serious dermatologic reactions including SJS

34
Q

pharmacokinetic considerations for carbamazepine

A

auto-inducer: max autoinduction is 2-4 weeks after initiation or dose change; re-adjust dose at 3-4 weeks

many drug interactions; macrolides decrease carbamazepine metabolism causing toxicity

carbamazepine can cause subtherapeutic INR w/ warfarin

35
Q

valproic acid dosing

A

loading dose 15-20 mg/kg IV
maintenance dose initially 10-15 mg/kg/day in 2-3 divided doses
weekly increase 10 mg/kg/day and target 30-60 mg/kg/day in 2-3 divided doses

36
Q

valproic acid therapeutic range

A

50-100

37
Q

valproic acid side effects

A

dose dependent: GI complaints (minimized w/ enteric coated form or food), alopecia, thrombocytopenia, platelet dysfunction

independent: hepatotoxicity: unpredictable/fatal, most common in young children <2, on polytherapy, within first 6-12 months of therapy (check LFTs if patients complain of n/v, lethargy, anorexia, edema)

38
Q

valproic acid PK considerations

A

many drug interactions
increases carbamazepine, lamotrigine, phenytoin, phenobarbital

39
Q

phenobarbital dosing

A

loading: 15-20 mg/kg IV
avoid rapid administration > 60 mg/min due to hypotension, caution if hemodynamically unstable

maintenance 1-3 mg/kg/day in 2-3 divided doses

40
Q

phenobarbital therapeutic level

A

15-40

41
Q

phenobarbital side effects

A

concentration dependent: sedation, respiratory depression, hypotension

independent: hypersensitivity, hyperactivity, altered concentration, altered learning, depression

42
Q

clinical pearls for fosphenytoin

A

phenytoin prodrug dosed by phenytoin equivalents (PE) with loading dose 10-20 mg/kg PE

benefits over phenytoin: less infusion reactions, administration (peripheral IV, can give IM if no IV access)

43
Q

clobazam pearls

A

benzodiazepine (CIV)
adjunct treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients 2 years+

somnolence/sedation, avoid abrupt withdrawal, pregnancy C

44
Q

ethosuximibe pearls

A

first line for absence seizures
TDM required: therapeutic level is 40-100

45
Q

ezogabine pearls

A

adjunct for partial seizures
QT interval prolongation within 3 hours of admin (monitor)
REMS program for urinary retention

46
Q

felbamate pearls

A

reserved for patient not responding to other AEDs

side effects include aplastic anemia, acute liver failure: patient or guardian must sign consent form

47
Q

gabapentin pearls

A

second line for partial seizures +/- generalizations
highly used for off label indications (neuropathic pain, migraines, bipolar)
can accumulate in renal disease so have to adjust dose

48
Q

lacosamide pearls

A

adjunct treatment of partial seizures
CV
prolongation of PR interval: caution in conductance problems
must dispense each Rx with med guide

49
Q

lamotrigine pearls

A

interaction with valproic acid increases the serum concentration by 200%; inducers like phenytoin/carbamazepine accelerate metabolism

rash due to stevens johnson syndrome: high initial dose, concurrent valproic acid use, rapid escalation (use low dose and slow titration to avoid SJS)

50
Q

levetiracetam pearls

A

100% bioavailable after PO administration (1:1 IV:PO)
no induction/inhibition hepatic interactions (basically only drug with no interactions)

overall best safety profile and minimal ADEs

51
Q

oxcarbazepine pearls

A

not a prodrug of carbamazepine, but structurally related. potentially first line for primary generalized convulsive seizures. no auto induction but still an enzyme inducer (less potent than carbamazepine or phenytoin)

25-30% carbamazepine cross-sensitivity with rash

hyponatremia in 2.5%

when transitioning from carbamazepine: CBZ dose per day x 1.5= OXC dose/day (you can’t just switch on same dose)

52
Q

rufinamide pearls

A

adjunct for generalized seizures of Lennox-Gastaut syndrome
ADEs QT shortening
contraindicated in familial short QT syndrome

53
Q

tiagabine pearls

A

2nd line for partial seizures in patients who failed initial therapy
no inhibition or induction of hepatic enzymes
CYP3A4 substrate (phenytoin, carbamazepine, and phenobarbital decrease serum concentration)

54
Q

topiramate pearls

A

first line AED for partial seizure
migraine prophylaxis
ADEs are CNS effects (word finding problems, slurred speech, confusion, etc) and kidney stones (stay hydrated)

55
Q

vigabatrin pearls

A

black box warning, REMS for permanent vision loss in infants, children, adults
(blind as a bat)

56
Q

zonisamide pearls

A

ADEs include idiosyncratic severe skin rash, SJS (d/c immediately)
advantage is long half life= once daily dosing

57
Q

pearls of medical marijuana in seizures

A

potential drug interactions: induced by carbamazepine and phenytoin, inhibited by ketoconazole
epilepsy is an approved indication in PA

58
Q

folic acid supplementation in pregnancy and other pearls

A

use 0.4 mg/day
take the best drug for seizure type and monotherapy if possible; avoid valproic acid monotherapy or polytherapy in the first trimester if possible

59
Q

definition of status epilepticus

A

a neuro emergency that can cause brain damage, death
at least 5 minutes of continuous seizures
or at least 2 discrete seizures between which there is incomplete recovery of consciousness

60
Q

treatment for wernicke’s encephalopathy

A

thiamine 50-100 mg IV

61
Q

first line agent for status epilepticus

A

benzodiazepines (LORAZEPAM)
generally 1-2 doses will stop seizures within 2-3 minutes

62
Q

option for seizures if there is no IV access

A

diazepam gel for rectal delivery
intranasal diazepam (6+) or midazolam (12+)

63
Q

second to third line agents for status epilepticus

A

2nd line: phenytoin or fosphenytoin IV if unresponsive to lorazepam

3rd line: phenobarbital or valproic acid

refractory status epilepticus: search for the actual cause, intubate patient, propofol, continuous IV infusion of midazolam or pentobarbital (get norepi ready since causes hypotension)

neurology/psychiatry (22 decks)

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