Exam 3: Seizure Flashcards
Seizure
paroxysmal disorder of the CNS characterized by abnormal cerebral neuronal discharges with or without loss of consciousness
Epilepsy
repeated seizures due to damage, irritation, and/or chemical imbalance in the brain which leads to a sudden, excessive, synchronous electrical discharge
Seizures are a result of what?
disordered, synchronous, and rhythmic firing of a population of brain neurons (synchronized hyperexcitiability)
Focal Onset
classified to either aware or impaired awareness
motor or non-motor onset
and may progress to focal to bilateral tonic-clonic (generalized seizure) (with aura)
Generalized Onset
Classified to either motor (tonic clonic or other motor) or non-motor (absence seizure)
Unknown Onset
Classified to either motor (tonic clonic or other motor) or non-motor
Where do focal seizures begin
temporal lobe
What are generalized seizures presumed to be
genetic
Partial Seizure Spread
seizure activity spreads from a focus in one part of the brain (focal seizure)
Partial Seizure Secondary Generalized
focal seizures frquently progress to secondary generalized seizures via projections to the thalamus (focal to bilateral)
primary generalized seizure
propagate via diffuse interconections between the thalamus and cortex (no discrete focus)
earliest clinical signs show involvement of both brain hemispheres
AWARE type of seizure
simple partial
no loss of consciousness
subjective experiences (auras) also occur (sense of fear, unpleasant smell, abdominal discomfort)
Impaired Awareness seizure
complex partial
most common among focal seizures
clouding of consciousness
staring
repetitive motor behaviors (swallowing, chewing, lip smacking)
disturbances of visceral, emotional, and autonomic systems
seizure followed by confusion, fatigue, and throbbing headache
aura is common
postictal state due to impaired awareness
postictal state
after a seizure, a pt will not recover a normal level of consciousness immediatlely
may last seconds to hours
confusion, disorientation, anterograde amnesia
absence seizure
typical: petit mal
- brief loss of consciousness (10-45 seconds)
- staring or eye flickering
- begin abruptly
- often repetitive
- may not realize it after the seizures
- no convulsions, aura, or postictal period
Atypical
- slower onset than typical
more difficult to control
First phase generalized seizure
tonic phase
begins abruptly, often with diaphragm contraction (no aura)
Second phase generalized seizure
clonic phase
begins as relaxation periods become more prolonged
involves violent jerking of the body that lasts 1-2 minutes
Therapeutic Goal
bring seizures under control within 60 minutes
does one seizure define epilepsy?
no
Drug therapy withdrawal
gradually withdrawn in patients who have been clinically free of seizures for 2-5 years
depolarization
involves the activation of AMPA and NMDA channels by the excitatory neurotransmitter glutamate and voltage gated calcium channels
influx of cation Ca2+
Hyperpolarization
activation of GABA receptors
influx of chloride ions
efflux of potassium
homeostasis
neuronal signaling (depolarization) is normally dampened by feed-forward and feedback inhibition involving GABAergic neurons
disrupted E/I balance
Tonic Phase Mechanism
GABA mediated inhibition disappears
Glutamate-mediated AMPA and NMDA receptor activity increases