Epilepsy: Classification and Etiology Flashcards
Broadly, what part of the brain do seizures affect?
The cortex.
What are 3 things that can cause a provoked seizure?
Fever, acute head trauma, CNS infection.
Are provoked seizures indicative of epilepsy?
No.
Is an unprovoked seizure epilepsy?
No.
What is epilepsy? (simple definition)
Recurrent unprovoked seizures.
How does prevalence of epilepsy vary with age?
Bimodal: peaks in infants/children and adults > 70 yrs.
What did the Bible get right about epilepsy?
Fasting -> ketosis actually helps epilepsy sometimes. (Does this actually happen in the Bible?)
What did the 1850’s masturbator-haters get right about epilepsy?
Bromide salts are an effective treatment for epilepsy (with the side effect of reduced libido).
What’s a “Jacksonian March”?
Motor seizure propagating along primary motor cortex. (Jackson correlated seizure signs with anatomic location in brain)
What was the first modern medication for epilepsy? (not bromide salts) Drug class? Mechanism?
Phenobarbital. A barbituate.
Acts on GABA-A to facilitate inhibitory signaling. (more coverage of this in next lecture)
What are 2 basic rules of symmetry / asymmetry in a normal EEG?
Front of brain should look different from back.
Left should look the same as right.
What do the waves on an EEG actually represent?
Extracellular current from summed activity from many neurons, especially pyramidal cells.
What are 4 factors in the International League Against Epilepsy (ILAE) revised classification of epilepsy?
Mode of epileptic seizure onset.
Epilepsy syndrome type.
Epilepsy etiology.
Evolution over time.
What are 3 modes of seizure onset?
Generalized.
Focal.
Unknown / unclear.
What are 6 types of generalized onset seizures? Brief description of each?
Absence - arrest of activity, staring, unresponsive.
Myoclonic - quick muscle jerks, usu. symmetric.
Tonic-clonic - convlusions: bilateral extension progressing to rhythmic shaking.
Tonic - extremity extension and muscle stiffening.
Clonic - rhythmic shaking (without tonic phase).
Atonic - sudden loss of trunk/neck tone -> falling.
(7th bonus type = epileptic spasm/ “West syndrome”: neck and trunk flexion, extremity extension)
How do the onsets of generalized seizures look on an EEG?
Left and right are the same.
Key points of the ILAE description of the onset of generalized seizures? (3ish things)
Rapidly engage bilateral networks.
Bilateral networks include cortical and subcortical structures.
Doesn’t necessarily involve all cortical areas.
Why might a seizure that looks like it had generalized onset might not actually have had one?
Focal onset seizures with rapid secondary generalization can mimic generalized onset seizures.
Key points of the ILAE description of the onset of focal seizures? (2ish things)
Originate in networks limited to one hemisphere.
Onset consistent from one seizure to the next.
Name 4 different localizations within the frontal lobe for focal seizures and a brief description of their signs/symptoms.
Motor strip: clonic shaking of contralateral limbs.
Midline premotor area near midline - complex, bilateral hypermotor activity “wild, flailing movements.”
Broca’s area - expressive language dysfunction (non-fluent aphasia).
Fronto-polar - arrest of activity, hypomotor (easy to confuse with Absence).
Signs and symptoms of focal onset seizures localized to the temporal lobe? (4 things)
Aura.
Arrest of activity.
Unresponsiveness.
Motor automatisms.
What are motor automatisms?
“Meaningless,” repetitive motions. Recall the guy in the video fiddling with a plastic bag. Associated with temporal lobe seizures.
Signs and symptoms of focal onset seizures localized to the parietal lobe? (2 things)
Sensory signs.
Signs based on propagation to other lobes.
(Parietal seizures are subtle.)
Signs and symptoms of focal onset seizures localized to the occiptal lobe?
Visual signs. Can be seeing new stuff, such as auras. Or can lose vision.
3 broad causes of epilepsy?
Genetic.
Structural / metabolic.
Unknown.
What’s a developmental structural cause of epilepsy?
Malformations of cortical development.
Some epilepsy is caused by mutations in a single gene. What kind of gene are most of these?
Ion channels / related proteins.
2 different classifications of an epilepsy’s evolution over time?
Self-limited (or not).
Treatment-responsive (or not).
What’s one reason why it’s important to distinguish between generalized vs. focal epilepsy?
Treatments for them are different, and treatments for one often don’t work for the other.
Does childhood absence epilepsy (CAE) have effects if the seizures abate? What does this tell you about epilepsy?
Yes. People who had CAE as children score much lower psychosocially (income, education level, emotional problems, etc. etc.) later in life than average. Suggests that seizures are a symptom of problem with brain development (which the drugs can’t fix).
