Epilepsy Flashcards
Define epilepsy
A neurological disorder, representing a brain state that supports recurrent and unprovoked seizure
Define seizure
Abnormal, paroxysmal changes in the electrical activity of the brain which reflect large scale synchronous discharge of neuronal networks
Define Epileptogenesis
The process by which normal brain function progresses towards generation of abnormal electrical activity
What does a generalised seizure involve?
Both hemispheres of the brain + loss of consciousness
Name the 3 types of generalised seizure
Tonic-clonic seizure (grand mal)
Absence seizure (petit mal)
Atonic seizure
What is tonic-clonic seizure preceded by?
an aura
Name the phases of tonic-clonic seizure
Premonition Pre-tonic-clonic phase Tonic phase Clonic phase Postictal period
What age does petit mal usually affect?
Children (aged 3-13)
What does absence seizure present as?
Eyes rolling back and blinking
What happens in a Atonic seizure?
Sudden drop due to loss of muscle tone
May not lose consciousness
How is epilepsy diagnosed?
Occurence of 2 or more seizures
Eye witness
MRI
What is Status epilepticus?
medical emergency form of epilepsy
What is characteristic of status epilepticus?
Seizure lasting more than 5m
Or
More than 1 seizure in 5m with no regain of consciousness
What is a partial/focal seizure?
Involves only one area of the brain and does not result in loss of consciousness
What is partial/focal usually preceded by?
Aura
sense of awareness a seizure is about to occur
Which is the most common partial/focal seizure?
Temporal lobe epilepsy
What regions of the hippocampal areas is there a loss of cells?
CA2 and CA3 regions
What does sprouting of mossy fibres of granule cells lead to?
reverberant excitatory circuits
What cells are also lost which are GABAergic?
chandelier
What is a characteristic of chandelier cells?
GABAergic
What do chandelier cells control?
activity of cortical pyramidal cells
Where do chandelier cells synapse onto?
initial axonal segment
What does loss of inhibitory chandelier cells increase the risk of?
abnormal excitatory activity
What may also occur structural change wise? (related to glutamate)
Glial abnormalities
Is there increased or decreased GABAergic inhibition?
Decreased
What is increased in epilepsy? (In cellular mechanisms)
Glutamate-dependent excitation
How is the burst firing profile and paroxysmal depolarising shift achieved?
Ca+ mediated depolarisation
Voltage gated Na+ opens -> action potential (PROLONGED!)
Voltage gated K+ opens -> HYPERPOLARISATION
K+ REMAIN OPEN
What is the aim of anti-epileptic drugs?
Control firing of action potentials
Give examples of Na+ Channel blockers
Phenytoin Carbamazepine Sodium valproate Lamotrigine Topiramate
What does Na+ Channel blockers do?
Prevents depolarisation
Give two examples of Ca2+ Channel blockers
Ethosuximide
Gabapentin
Pregabalin
Give examples of GABAergic System modulators
Benzodiazepines
Barbiturates
Give examples of neurotransmitter modulators
Levetiracetam
Tiagabine
Vigabatrin
Give other treatments of epilepsy
Lobe resection Corpus callosotomy Vagal nerve stimulation Deep brain stimulation Ketogenic diet (mainly for kids)
