Nervous System Flashcards
What is meant by a seizure?
A seizure is a sudden irregular discharge of electrical activity in the brain.
It involves: sensory disturbance, convulsions (uncontrolled shaking movements) and unconsciousness.
What is epilepsy?
A neurological disorder which is marked by recurrent episodes of sensory disturbance/ LOC/ convulsions with abnormal electrical activity in brain.
What is the difference between partial and generalised seizures?
Partial= only one bit of the brain affected.
Generalised= many parts of the brain affected.
What are the different types of generalised seizures?
Absence Myoclonus Tonic clinic Tonic Atomic
Explain what is meant by the following seizures….
Absence Myoclonic Tonic clinic Tonic Atonic
Absence= daydreaming
Tonic clinic: muscles tense and then convulse
Myoclonic: brief shock like muscle jerks
Status epileptics: medical emergency
Myocolonic: brief shock like muscle jerks
Atonic: without tone ‘drop attack’
Tons: increased tone (stiffen, then relax).
The causes of epilepsy can be primary (idiopathic)- no apparent cause and may be inherited.
Or
Secondary (symptomatic)
What can some of the causes of epilepsy be?
VITAMIN C V= vascular= stroke/TIA I= infection= abscess/ meningitis T= trauma= jntracerebral haemorrhage A= auto immune= systemic lupus erythromatous M= metabolic= hypoxia, electrolyte imbalance, hypoglycaemia, thyroid dysfunction I= Iatrogenic= drugs/alcohol withdrawal N= neoplastic= intracerebral mass
What are some anti epileptic drugs you could use?
Carbamazepine, lamotrigine, phenytoin.
How does carbamazepine, lamotrigine and phenytoin work?
They are all anti epileptics which are sodium channel blockers, they cause Na channels to be in a constant inactive state so you don’t get action potentials.
What are the side effects of phenytoin?
Dizziness
Fatigue
Ataxia
Diplopia
- if used in pregnancy then they can lead to common congenital malformations like: cleft lip palate, congenital heart disease.
You can’t use phenytoin for long as it can become toxic and cause nausea, CNS dysfunction (confusion, nystagmus, ataxia.
What is the first line drug for people with generalised/tonic- clinic seizures?
Sodium valproate
Indirect increase in GABA synthesis
Ca2+ channel blocker- prevents depolarisation
As well as being Na+ channel blocker.
Give some side effects of sodium valproate?
Dizziness, fatigue, ataxia, diplopia, weight gain.
Why would you have to be careful if taking sodium valproate when taking liver enzyme inhibitors?
Liver enzyme inhibitors cause the sodium valproate levels to increases and therefore you have to reduce the dose.
How to levetiracetam work?
Binds to synaptic vesicles to inhibit the pre synaptic calcium channel activity, therefore you get inhibition of neurotransmitter release from the pre synaptic neurone.
What are the interactions of carbamazepine, phenytoin and sodium valproate?
So carbamazepine and phenytoin, are both liver enzyme inducers so their levels can reduce too rapidly, whereas with sodium valproate, this is a liver enzyme inhibitor so levels can get too high.
What would you advise someone taking the COCP and carbamazepine/phenytoin?
As phenytoin and carbamazepine are liver enzyme inducers then they can cause the oestrogen levels of COCP to fall too low, person should have a higher COCP dose and also use other protective measures.