Epilepsy Flashcards
Understand the definitions of epilepsy and seizures and the difference between the two Understand the basic epidemiology of epilepsy Understand the principles of the different anti-epileptic drugs' mechanisms of action Give examples of different drugs that exploit these different mechanisms
What is epilepsy?
The tendency to recurrent, unprovoked seizures
What is a seizure?
An abnormal, excessive, synchronised discharge of cerebral neurons
Why must an individual have more than one epileptic-type seizure to be diagnosed with epilepsy?
Only 50% of individuals who present with a seizure will go on to have a second within 2 years - to this prevents overtreatment
What is the UK prevalence of epilepsy?
0.5%
Name the three more prevalent neurological conditions
Migraine, stroke, dementia
What percentage of people will have developed epilepsy by the time they are 90?
5%
Describe the appearance of SUDEP on EEG
A tonic-clonic seizure pattern followed by the permanent cessation of brainwave activity
How much more likely to die are epileptics than the general population?
3-4x
State at least 3 acquired causes of epilepsy
Tumours, stroke, infection, TBI
State 3 inherited causes of epilepsy
Vascular malformations, metabolic disorders, malformations of cortical development (MCDs)
Name the compound released by neural cells in chronic epilepsy which perpetuates seizures via positive feedback
High-mobility group box 1 (HMGB1)
Name the receptor which HMGB1 acts on
Toll-like receptor 4 (TLR4)
Name 2 inflammatory mediators released by HMGB1 binding to its receptor
IL-1beta and NF-kappaB
How do IL-1beta and NK-kappaB lead to chronic seizures?
They bind to NMDA receptors, leading to a calcium influx and hyperexcitability of neurons, leading to chronic seizures and epilepsy
How do EEGs measure brain activity?
By recording the potential change in an area of the brain relative to the areas around it. This detects neuron firing as it is associated with a flow of sodium ions
How does blinking cause an EEG artefact?
The eyeball is positive compared to the vitreous. When someone blinks, the eyeball moves up and this generates an artefact
What is the standard discharge on an EEG recording of an absence seizure?
3Hz
Describe a tonic-clonic seizure
The patient’s muscles all become stiff at once - accompanied by cessation of breathing - followed by uncontrolled muscle jerking. This is followed by deep unconsciousness with deep breathing to repay the oxygen debt
Describe a tonic seizure
Sudden onset muscle stiffness followed by deep unconsciousness
Describe an atonic seizure
Sudden onset of complete loss of muscle tone
Describe the consequence of a focal seizure at the occipital pole
Simple visual hallucinations, e.g. balls of light
Describe the 3 components of a typical focal temporal lobe seizure
An aura - typically a disturbance in memory - followed by a period of unresponsiveness with awareness, followed by automatisms and involuntary movements
Name at least 2 anti-epileptic drugs which enhance GABA inhibition
Benzodiazepines, phenobarbital, topiramate, sodium valproate
Name an anti-epileptic drug which reduces glutamate-mediated excitation at the pre-synapse
Topiramate, levetiracetam
Name an anti-epileptic drug which reduces glutamate-mediated excitation at the post-synapse
Topiramate, parampanel
Name an anti-epileptic drug which blocks the action potential via sodium channel depolarisation
Phenytoin, carbamazepine, sodium valproate, lamotrigine, topiramate
Name an anti-epileptic drug which acts on calcium T channels
Ethosuximide
