Lecture 23 + 24 - Epilepsy Flashcards
When does epilepsy become an emergent situation?
When the brain gets locked in an epileptic state.
48+ hours of lock = 50% mortality.
What is epilepsy?
A tendency to have recurrent seizures.
What are seizures?
A sudden uncontrollale burst of electrical activity in the brain.
Episodes of altered consciousness.
What is the basis for most epileptic diagnosis?
EEG.
Transient, abnormal focal neural discharges seen.
Recordings during periods between seizures.
Describe animal research on interictal activity.
Epileptic rate is trained to choose between 2 levers where one will activate a light.
If there is a pause, then the rat is getting the lever wrong.
If the rat is epileptic, it seems to do fine at the task but then if an interictal event occurs it struggles to identify the correct lever.
What are some causes of epilepsy (epileptogenesis)?
Genetic
Brain injury such as head trauma, stroke.
Brain infection such as HPV, measles.
Brain disease such as tumours.
Drugs.
Not well understood so hard to develop effective treatments.
What are some causes of seizure (ectogenesis)?
Drugs
Electrical stimulation (ECT)
Sensory triggers such as flashing lights, audiogenics.
Metabolic imbalances - can stop someone seizing by making them acidotic.
Hormonal state.
Brain state.
Temperature.
Fatigue/stress.
What is calcium network imaging?
Whenever a nerve cell is active, calcium enters the cells.
Using dyes that bind to calcium allows us to see a cellular visualisation of seizures.
Describe the spatial profile of a seizure.
Core territory where seemingly every neuron is active and this projects forward glutamatergic barrages on to this territory.
In turn this leads to a rapid recruitment of interneurons in this territory, providing a rapid feedforward restraint of pyramidal activity.
Describe the epileptic brain.
Has a pathological state that is easier to enter as there is a reduced protective barrier. Positive feedback mechanisms work together to create the sudden transition into the seizure state.
What are some anti epileptic drugs?
Phenytoin
Sodium valproate, carbamazepine
Benzodiazepines
Barbiturates
Tiagabine
Ethosuximide
What are some other treatment options?
Neurological resection - discrete, identifiable focus of pathology, away from functionally important areas, irreversible.
Brain stimulation - possibly for on demand treatment, large parameter space.
Gene therapy - finding a gene that has gone wrong and reintroducing it back into the brain.
What do bistables in the brain allow for?
Allows sudden shifts in what the brain is processing.
What are focal seizures?
Originate from a distinct part of the brain and involve only one hemisphere.
Associated with a well-delineated structural abnormality of the affected brain region from which the synchronised electrical activity originates.
What can focal seizures present with?
Sensory changes.
Dyscognitive seizures where a person cannot communicate or respond to commands.
