epilepsy pathophysiology and pharmacology Flashcards
what is epilepsy?
a tendency to have recurrent seizures
what are seizures?
episodes of altered consciousness brought about by signals flowing in the wrong way which cause wrong activity patterns in the brain.
what is ictogenesis?
the development of a seizure
what is ictal?
the seizure
what is epileptogenesis?
the development of a seizure
what is interictal?
the time between seizures
what does paroxysmal mean?
sudden, violent outbursts
what are 3 major causes of death in epilepsy?
- status epilepticus
- trauma
- SUDEP
what is status epilepticus?
when epileptic fits follow one another without recovery of consciousness between them
what does SUDEP stand for?
Sudden Unexplained Death in Epilepsy
how is epilepsy diagnosed?
- looking at the patient/observations
- feedback from others who have observed these things
- baseline EEG to look for interictal activity
what is interictal activity?
these are transient and abnormal focal neural discharges seen on electroencephalogram (EEG) - happens between seizures
what are some co-morbidities with epilepsy i.e. conditions that arise with epilepsy?
- Excess mortality
- Memory deficits
- Schizophrenia
- Depression, stress, anxiety
- Downward social movement
what can cause epilepsy (epileptogenesis)?
- genetic factors
- brain injury e.g. stroke
- brain infection e.g. measles and HPV
- Brain disease e.g. tumours
- Drugs (including alcohol!)
what can cause seizures (ictogenesis)?
- drugs
- electrical stimulation
- sensory triggers e.g. flashing light, sounds
- metabolic imbalance e.g. pH levels change
- hormonal state
- brain state
- temperature
- fatigue/stress
what effect do absence seizures have on the brain?
they compromise brain function as the discharge released blocks the flow of activity through the thalamus - known as compromised computation (where the brain can’t function well as it has been compromised)
what are absence seizures?
when an individual blanks out for a few seconds
what 2 synchronised activities in the brain are the basis of memory
long term potentiation and long term depression
is epilepsy the price we pay for cortical function and why
yes because the cortical function involves sunchronised neuronal activation but when this is not so, due to signals flowing in the wrong direction because of neuronal binding problems we get wrong activitiy patterns in the brain. thsi results in seizures as it is recurrent which leads to epilepsy
since epilepsy is genetic what does that mean for treatment
it means we can develops medicines personalised to the patients genome with advances in genome sequencing
what surgeries are available to those with epilepsy
- resection ( cutting out tissue or part of an organ)
2. brain stimulation ( electrical or optogenetic)
which anti epileptic drugs suppress neuronal excitation ( so signal is not generated)
phenytoin
sodium valproate
carbamazepine
which anti epiletic drugs enhance inhbiition ( so signal is not transmitted)
benzodiazepines
barbiturates
tiagabine
how does phenytoin work
stabilises inactive state of NA channels
how does sodium vamproate work
inhibit Na channels
how does carbmazepine work
inhibits NA channels
how does benzodiazepines work
elongates GABAa channels opening time
how does barbituarates work
increases GABA current by increasing affinity for GABA
how does tiagabine work
blocks cellular GABA uptake
how does ethosuximide work
target voltage dependent CA2+ channels (VDCCs) for treatment of absence seizures
what do phenytoin carbamezepine and phenobarbital interact work
induce the metabolism:
- anticovulsants
- warfarin
- oral contraceptives
which are teratogenic :
- anticovulsants
- warfarin
- oral contraceptives
anticonvulsants e.g. sodium valproate
these are drugs used to prevent or reduce the severity of epileptic fits or other convulsions
side effects to taking carbamazepine
diplopia ataxia drowsiness hyponatraemia agranulocytoss aplastoc anaemia
which has a more narrow therapeutic window phenytoin or carbamazepine
pehnytoin 10-20
carbamazepine 20-50
so pehnytoin
side effects to phenytoin
nystagmus
ataxia
gingival hyperplasia
hirsuitsm
what lifestyle change can a patient make to better their epileptic condition
go on a ketogenic diet
what is a ketogenic diet
high fat
adequate protein
low- carb diet
how does a keto diet help with epilepsy
diet forces the body to burn fats rather than carbs.
fat is converted into fatty acids and ketone bodies
higher levels of ketone bodies in the blood leads to reduction in the frequency of epileptic seizures
