Epilepsy

Question 1

what is an important feature in the pathology of epilepsy

Answer 1

loss of surround inhibition.

one neuron synapses on many secondary neurons. without surround inhibition, a high number of secondary neurons will fire causing widespread electrical activity/depolarisation in a part of or whole brain

Question 2

epilepsy can be treated by enhancing GABA inhibitory systems. what are some drugs that do that

Answer 2

benzodiazepines (e.g diazepam) - increases affinity for GABA at GABAa receptors

barbiturates (e.g. Phenobarbitone) - prolongs the open state of GABA gated Chloride channels

Question 3

use dependant voltage gated Na channel blockers can be used to treat epilepsy. name two drugs and explain how they act

Answer 3

carbamazepine, phenytoin

bind inactivated v. g. Na channels (e.g. once depolarisation has occurred). increases refractory period of the membrane. so less action potentials can fire in a given time

note: they only work on neurons firing at high frequencies (since they are use-dependant)

Question 4

name one drug used to treat absence seizures

Answer 4

ethosuximide. thought to inhibit thalamic neurons by blocking voltage gated Ca channels

Question 5

name one drug used to treat both tonic clonic and absence seizures. what type of drug is it

Answer 5

lamolrigine. use dependant Na blocker