Week 8 - Seizures & Antiepileptics Flashcards
what is a seizure
- temporary disturbance in cerebral function caused by abnormal, excessive, and synchronous electrical discharge of cortical neurons
define epilepsy
- group of disorders characterized by recurrent seizures
what is the cause of seizures (2)
- 75% idiopathic
- other are secondary to brain injury
list examples of brain injuries that cause seizures
- stroke
- trauma
- infection
- tumor
- hemorrhage
- renal failure
- hypoglycemia
- eclampsia
- electrolyte disturbance
- drug induced
what are febrile seizures
- seziures induced by a fever
who do febrile seizures commonly occur in? who are they dangeous to>?
- common = children
- more dangerous to adults
what are 2 current theories regarding the pathogenesis of seizures
- disruption of GABA-secreting or adenosine secreting inhibitory neurons
- elevated extracellular K+
how do most anticonvulsant drugs work
- inhibiting voltage-gated sodium or calcium channels (which typically excite the brain)
- increasing the amount of GABA at inhibitory synaptic junctions
what is a common cause of seizures in a minority of clients
- certain stimuli triggering a seziures
what types of stimuli may induce a seizure (6)
- loud noises
- bright lights
- stress
- excessive fluid retention
- hypoglycemia
- hyperventilation-induced alkalosis
what are the 2 categories of seizures
- generalized
2. focal
what are generalized seizures
- involve uncontrolled electrical activity of the entire brain
what is the focus of generalized seizures
- deep within the cerebrum or brainstem
what do generalized seizures result in
- loss of consciousness
what causes generalized seizures (2)
- spontaneous
2. secondary to focal seizures
what does a tonic seizure involve (6)
- sudden stiffening of the muscles
- generalized muscle contraction
- rigid body
- extended limbs
- jaw clenched
- resp stops
what does a clonic seizure involve
involve:
- rhythmic twitching of the muscles due to muscles contract & relaxing
- increased salivation
- incontinence is frequent
what is the most common seizure associated w epilepsy
- tonic-clonic seizures
what is a tonic clonic seizure
- seizure consisting of a clonic & tonic phase
what can a tonic-clonic seizure cause (2)
- hypoxia –> due to stopped resp
- hypoglycemia –> due to increased muscle activity
what is status epilectus
- recurrent & continuous seizures without return of consciousness between
what can status epilepticus cause (4)? what does this mean?
can cause:
- hypoxia
- hypoglycemia
- acidosis
- potential brain damage
= life-threatening
what is an absence seizure? what characteristics are seen (3)?
- brief loss of consciousness resulting in “starring into space”, twitching of the eyelids, and lipsmacking
who do absence seizures commonly occur in
- young children
how long do absence seizures last? how often do they occur?
- 5-10 sec
- several times throughut the day
what occurs following an absence seizure
- normal activity is resumes
- no memory of the event
is an absence seizure a general or focal seizure
- generalized
what is a focal seizure
- seizures that arise from specific areas & localized damage/dysfunction in the brain
what are 4 types of focal seizures
- motor
- sensory
- autonomic
- psychic
what do motor seizures manifest as
- repeated motor activity due to damage to the motor cortex
- occurs in the extremity depending on where damge is
what do sensory seizures manifest as
- tingling sensation
- auditory or visual sensations
ex. ringing ears, see things
what is a progressive seizure
- motor seizure involving clonic contractions that begin in one region of the body but spread progressively to other areas (often the face)
what is an example of a type of progressive seizure
- Jacksonian’s seizure
how are focal seizures classified? what are they based on?
- aware
- impaired awareness
based on memory of the seizure
what is an aura
- an unusual sensory sensation prior to the seizure
what other signs may occur before seizures?
- nausea
- muscle twitching
what are meds for seizures called
- antiepileptic (AED) or
- anticonvulsants
what is the goal of drug therapy for seizures
- control or prevent seizures while maintaining a reasonable quality of life
- minimize side effects & drug induced toxicity
how long do pts with seizure disorders typically have to be on AEDs
- typically lifelong
what type hydantoin drug is used for seizures?
phenytoin (dilantin)
what is the MOA of phenytoin
- blocks voltage-gated sodium channels
describe the therapeutic index of phenytoin
- very narrow
what type of seizure can phenytoin not be used for
- absence
what are 2 types of benzodiazipines that can be used for seizures?
- clonazepam & lorazepam
what is the MOA of benzos
- activate GABA receptors
what is GABA
- major inhibitory nt
= reduces the activity lvl of neurons & less likely to produce action potentials
what can benzos be used for
- absence seizures
what type of barbiturate is used for seizures
- phenobarbital
what is the MOA of barbiturate
- activates GABA receptors
- can mimic GABA
which is more potent, benzos and barbs
- barbs
- since they can also mimic GABA, they have a higher change of causing CNS & resp depression
list 3 other AEDS
- valproic acid
- carbamazepine
- gabapentin
what is the MOA of valproic acid
- blocks voltage gated Na channels
- increases GABA
what type of seizure can valproic acid be used for
- absence
what is the MOA of carbamazepine
- stabilizes voltage gated Na channels
- GABA agonists
what can carbamazepine be used for
- neurpathic pain
what is the MOA of gabapentin
- GABA analog that also increases GABA production
- may stabilize calcium channels
what can gabapentin be used for
- neuropathic pain
- restless leg syndrome
what is the drug of choice for status epilepticus ? why?
lorazepam –> have very quick onset
describe the adverse effects of AEDs
- numerous & vary per drug
- often result in need to change meds
- narrow therapeutic index
what do many AEDs require the monitoring of
- plasma lvls
