CNS 2 - Antiepileptics Flashcards
What are partial seizures?
When the abnormal electrical activity is limited to a certain area of the brain
What are generalised seizures?
When the abnormal electrical activity involves both hemispheres of the brain
What are simple generalised seizures?
Don’t involve loss of consciousness
What are the 2 main categories of seizures?
- Partial
- Generalised
What are the 2 types of generalised seizures?
- Simple
- Complex
What are complex generalised seizures?
Always involve loss of consciousness
What symptoms would be seen during a seizure affecting the motor cortex?
Body convulsions
What symptoms would be seen during a seizure affecting the hypothalamus?
Autonomic reflexes e.g. salivating, sweating
What symptoms would be seen during a seizure affecting the reticular formation?
Loss of consciousness
What factors are triggers for seizures? (4)
- Change in blood glucose/pH
- Stress
- Fatigue
- High sensory input e.g. flashing lights
What can cause the development of epilepsy? (5)
- Head injury
- Local lesion (e.g. bleed)
- Tumour
- Infection
- Genetics
How is epilepsy diagnosed
EEG
What is a grand mal seizure?
- Typical loss of consciousness and violent convulsions
- Also known as tonic-clonic seizure
- Generalised
What is a petit mal seizure?
- Absence seizure
- Characteristic oscillatory trace on EEG
- Generalised
What can happen when grand mal seizures are uncontrolled?
Neuronal death
What mutations can cause inherited forms of epilepsy? (4)
- Na+ channels (gain of function)
- K+ channels (loss of function)
- Nicotinic receptors
- GABA receptors
What animal models are used to study epilepsy? (3)
- Genetic models
- Chemical models
- Kindling model
What are genetic models for epilepsy?
Genetically modify rodents/zebrafish to introduce mutations which are associated with epilepsy in humans in order to study drug effects
What chemical models are used to study epilepsy? (3)
- Penicillin crystals cause seizures when applied directly to the brain by blocking GABA receptors
- PTZ blocks GABA receptors and causes seizures
- Kainate is an agonist for glutamate receptors which can cause seizures
What is the kindling model for epilepsy?
- Repeatedly apply electrical stimulus to an area of the brain over time
- Animal develops partial seizures in that area
Which drugs treat epilepsy by increasing inhibitory GABA transmission? (4)
- Benzodiazepines (emergency)
- Barbiturates (rarely used)
- GABA uptake inhibitors e.g. tiagabine
- Metabolic inhibitors e.g. valproate, vigabatrin
What is status epilepticus?
An emergency situation where a seizure doesn’t end
How is status epilepticus treated?
IV diazepam
How is GABA made?
Glutamate converted into GABA by GAD enzyme
