Exam 3: Seizures (Yang) Flashcards
(54 cards)
What does focal onset of seizures mean?
- aware and impaired awareness
- motor and non-motor onset
- may progress from focal to bilateral tonic-clonic
what does generalized onset of seizures mean?
- motor (clonic or other motor)
- non-motor (absence seizures)
what does unknown onset of seizures mean?
- motor (clonic or other motor)
- non-motor
- unclassified
What is the MOA of a focal seizure? how does it progress to bilateral?
- spreads from one part of brain (neocortex)
- progress to secondary generalized via projections to the thalamus
What is a primary generalized seizure?
Propagate via diffuse interconnection between thalamus and cortex (no discrete focus). Earliest clinical sign show both brain hemispheres
What is the EEG activity of a focal wave?
only one hemisphere and very normal but some tight temporal activity
what is the EEG activity of the generalized (tonic-clonic) wave?
all over the place and huge lines; involves both hemispheres
What is impaired awareness? What goes on within this seizure?
- most common among focal seizures
- clouding of consciousness
- aura is common
- postictal state due to impaired awareness
What is an absence: typical or atypical seizure? What goes on within this>
- brief loss of consciousness
- may not realize until after seizure
- no convulsions, aura, or postictal period
What seizure causes an aura?
focal to bilateral
What drugs aggravate or increase risk of seizures?
- alcohol
- theophylline
- CNS stims
- bupropion
- oral contraceptives
- withdrawal from depressants
- clozapine
what occurs during hyperpolarization of PDS?
influx of cl- resulting in GABAA receptor activation
In the PDC (paroxysmal depolarizing shift), what neurons are involved?
- Inhibitory Interneuron (GABAergic)
- Excitatory pyramidal neurons (glutamatergic)
What happens in the depolarization phase of PDS?
Activation of AMPA and NMDA by glutamate and Ca+ leading to influx of Ca2+
What happens in the hyperpolarization phase of PDS?
activation of GABA leading to influx of Cl- and efflux of K+
What is neuronal signaling?
depolarization; dampened by feed forward and feedback inhibition. Disrupted E/I balance
What is the MOA of anticonvulsant drugs?
stabilize and reduce neuronal excitability (reduce E/I balance)
How can we use the MOA of anticonvulsants? What drugs?
- enhance GABA-mediated neuronal inhibition (vigabatrin, tiagabine, benzos)
- antagonism of excitatory transmitters (glutamate)
- other targets (kepra)
What drug leads to non-linear PK? How is it eliminated?
- Phenytoin
- it is elimination kinetics are dose-dependent
What drug interactions are there with phenytoin?
- displaced from plasma proteins by other drugs
- induces P450s
what are the side effects of phenytoin?
- arrhythmia
- visual
- ataxia
- GI symptoms
- gingival hyperplasia, hirustism (hair growth)
- hypersensitivity reactions (skin rash)
What drug is phenytoin?
hydantoins
what drug is “azepines”?
iminostilbenes
What is the MOA of oxcarb and carb?
binds and stabilizes the inactivated state of Na+ channels