Epilepsy Flashcards
What is epilepsy?
a chronic disorder characterized by recurrent seizures
what is a seizure?
short term episode of abnormal firing of cerebral neurons (hyper-synchrony)
what are some causes of seizures?
fever head injury tumor heredity alcohol withdrawal metabolic disorder
What are the two main classifications of seizures?
partial
generalized
what is a partial seizure?
initiated in neurons in a localized area of one cerebral hemisphere
what are 3 types of partial seizures?
simple
complex
secondary generalized
what is a simple partial seizure?
no loss of consciousness; may experience an aura prior to seizure
what is a complex partial seizure?
impaired consciousness often with automatisms (ex: picking at shirt repetitively)
unable to recall events afterwards
what is a partial seizure with secondary generalization?
starts off localized, then spreads to activate both hemispheres (goes to thalamus first)
what are 2 types of generalized seizures?
tonic-clonic
absence
what is a generalized seizure?
simultaneous activation of both cerebral hemispheres
what is a generalized of tonic-clonic seizure?
tonic = rigid extension of limbs clonic = spasms, jerking of extremities
what is status epilepticus?
if a seizure goes on longer than 5-10min
what is a generalized absence seizure?
impaired consciousness sometimes with automatisms
sx: blink rapidly, eyes may roll back, smacking of lips
no aura occurs; happens quickly
what are 4 different MoA’s for seizure drugs?
1) blockage of voltage-dependent sodium channels (reduce rate of sodium channel opening)
2) inhibit glutamate exposure and reduce neuronal firing (decr. glutamate exposure and reduce neuronal firing)
3) Increase inhibitory GABA neurotransmission (enhances Cl influx, hyperpolarizes neurons and reduces neuronal firing)
4) block voltage-gated calcium channels (depolarization of thalamic neurons activates cortical neurons)
where do anti-epileptics work on voltage-gated sodium channels?
work on the state of converting inactive channel to a closed channel (inhibit conversion)
what are 4 drugs that are used to treat seizures?
carbamazepine (tegretol)
phenytoin
valproate
ethosuximide
what types of seizures can carbamazepine treat?
partial
generalized tonic-clonic
what is the MoA for carbamazepine?
inhibits voltage gated sodium channels
What are some adverse effects of carbamazepine?
double vision ataxia (poor balance, uncoordinated movements) nausea drowsiness (high doses) skin rash leukopenia (low count of WBCs)
what types of seizures can phenytoin treat?
phenytoin
what is the MoA of phenytoin?
blocks voltage-gated sodium channels
what are some adverse effects of phenytoin?
double vision ataxia eye movements gingival hyperplasia (gum inflammation) hirsutism (hair growth) peripheral neuropathy (Chronic) megaloblastic anemia (dysfunctional RBCs) osteomalacia (decreased calcification of bone)
What is the MoA of phenobarital and primidone?
enhance inhibitory effects of GABA
What are some adverse effects of phenobarbital and primidone?
drowsiness ataxia respiratory depression decreased motor skills skin rash psychological/physiological dependence
what is the MoA of gabapentin?
increases release of GABA from neurons; decreases GABA metabolism
what are some adverse effects of gabapentin?
sedation dizziness headache tremor ataxia GI (nausea, constipation)
what can topiramate be used for?
adjunctive therapy
monotherapy in partial and tonic-clonic seizures
what is the MoA of topiramate?
inhibits voltage sensitive sodium channels, incrases GABA effects and inhibits glutamate (AMPA) receptors
briefly describe the metabolism of topiramate
metabolism is affected by other anti-epileptics
what are some adverse effects of topiramate?
fatigue
dizziness
mental slowing
nausea
what can lamotrigine be used for?
adjunctive therapy
monotherapy for partial and absence seizures
what is the MoA of lamotrigine?
blocks voltage-gated sodium channels
what are some adverse effects of lamotrigine?
dizziness
headache
skin rashes
what kind of seizures can ethosuximide be used to treat?
generalized absence seizures
what is the MoA of ethosuximide?
blocks voltage-gated calcium channels
what are some adverse effects of ethosuximide?
stomach aches
vomiting
skin rash
may increase tonic-clonic seizures
what kind of seizure can clonazepam be used to treat?
generalized absence
what is the MoA of clonazepam?
enhances inhibitory effects of GABA
what are some adverse effects of clonazepam?
sedation
tolerance to anti-seizure effects
what kinds of seizures can valproate be used to treat?
generalized tonic-clonic
absence
mixed seizures (partial seizures, atypical generalized seizure)
what is the MoA of valproate?
voltage gated sodium and channel blocker
enhances inhibitory effects of GABA
what are some adverse effects of valproate?
risk of spina bifida
hepatotoxicity (pts under 2)
N/V
tremor
what are some other medical conditions anti-epileptics can be used for?
bipolar disorder (approved = carbamazepine, valproate) anxiety disorder alcohol abuse spascity migraine, cluster headache neuropathic pain (gabapentin)
what are two different meds used to treat status epilepticus?
IV diazepam (Valium) IV lorazepam phenytoin used for longer term control
can AEDs be used in pregnant women?
AEDs can harm the fetus, but risk/harm from uncontrolled seizures is greater
which meds enhance metabolism of oral contraceptives?
phenytoin
phenobarbital
which meds can cause enhanced vitamin D metabolism leading to osteomalacia and enhanced vitamin K metabolism leading to bleeding disorder?
phenytoin
phenobarbital
