Epilepsy & Anti-epileptic Drugs Flashcards
What is epilepsy?
Neurological disorder caused by abnormal electrical activity in the brain, associated with sudden recurrent episodes of sensory disturbance, loss of consciousness or convulsions.
What is a convulsion?
Uncontrolled shaking movements of the body due to repeated contraction and relaxation of muscles, occurs when the part of the brain responsible for movement is affected by a seizure.
What is a seizure?
A sudden irregular discharge of electrical activity in the brain causing a physical manifestation such as sensory disturbance, unconsciousness or convulsions.
What is status epilepticus?
Medical emergency when epileptic seizures occur continuously without recovery of consciousness in between, the patient can become unable to breathe.
What is the difference between a partial and general seizure?
Partial is when a single area of the brain is affected by seizure, general is when seizures are occurring all over the brain.
Seizures can start as partial and progress to become general.
Name the 5 types of general seizure.
Tonic Tonic-clonic Myotonic Atonic Absence
What are the 2 types of partial seizures?
Simple - same consciousness
Complex - loss of consciousness
What is temporal lobe epilepsy?
Common type of partial seizure, associated with auras such as auditory hallucinations or rush of memories as the temporal lobe is associated with hearing, language and memory.
What is frontal lobe epilepsy?
Common type of partial seizure where patient has abnormal movements on the contralateral side of the body, because the frontal lobe is associated with movement.
What is an absence?
Daydreaming like seizure.
What is a tonic seizure?
Increased tone in the muscles, muscles stiffen and relax (but not the same as muscle contraction).
What is a tonic-clinic seizure?
Has 2 parts, 1st part is tonic where there is increased muscle tone, 2nd part is clonic where they have convulsions.
What is a myotonic seizure?
Patient experiences muscle jerks similar to tonic clonic, but there is no increase in tone.
What is an atonic seizure?
When patient is without tone and has a ‘drop attack’ when they suddenly just drop.
What is an EEG and what is it used for?
Electroencephalogram - when electrodes are put on the head and they are stimulated with things that may induce a seizure - not diagnostic but is useful to support a diagnosis of epilepsy.
What are the 2 types of causes of epilepsy?
Primary - idiopathic
Secondary - there is a known cause for the epilepsy
Can epilepsy be inherited?
Yes, therefore you should always ask someone about family history.
What are the main classes of anti-epileptic drugs?
- Na+ channel blockers
- Ca2+ channel blockers
- GABA potentiators
Name 4 Na+ channel blockers used to treat epilepsy.
Carbamazepine
Lamotrigine
Phenytoin
Sodium valproate
What anti-epileptic would you give for status epilepticus?
Phenytoin
How do Na+ channel blockers treat epilepsy?
Blocking Na+ channels prevents action potentials from firing, preventing seizures.
What is the MOA of barbiturates and benzodiazepines and what are they used for?
Anti-epileptic drugs
GABA potentiators - enhance effects of inhibitory neurotransmitter GABA.
What is the MOA of sodium valproate?
Acts as both a Na+ and Ca2+ channel blocker - prevents depolarisation and action potential firing.
What anti-epileptic drug is used for general seizures?
Sodium valproate
What is gabapentin used for and what is its MOA?
Anti-epileptic drug
Inhibits GABA-transaminase, preventing breakdown of GABA and increasing inhibition of neuronal activity.
What is levetiracetam used for and what is its MOA?
Anti-epileptic drug
Binds to pre-synaptic vesicles and inhibits pre-synaptic Ca2+ activity, which prevents exocytosis and neurotransmission.
How are anti-epileptic drugs initiated?
Start with mono therapy and if ineffective, change to a different AED. If still ineffective, may need to add another AED.
How would you go about changing an anti-epileptic drug
New drug is titrated up to achieve therapeutic range, then old drug is slowly withdrawn over 6 weeks (drugs need to overlap).
When are anti-epileptics considered?
Usually considered after multiple similar seizures, but can be considered after only one if there is also:
- neurological deficit
- risk of further seizure is unacceptable
- EEG shows epileptic activity
- imaging reveals a structural abnormality
When should anti-epileptics be stopped?
Consider cessation if patient has been seizure free for at least 2 years, but consider patient’s livelihood (operating machinery).
Which anti-epileptic drugs are liver enzyme inducers?
Carbamazepine
Phenytoin
Which anti-epileptic drug is a liver enzyme inhibitor?
Sodium valproate
What are the general side effects of all anti-epileptic drugs?
- dizziness
- fatigue
- ataxia
- diplopia
Name some side effects specific to levetiracetam and gabapentin.
- irritability
- behaviour change
Name a side effect specific to carbamazepine.
Weight gain
Name side effects specific to lamotrigine.
- tics
- insomnia
Name some specific side effects of sodium valproate.
- weight gain
- very teratogenic - decreases serum folate leading to neural tube defects
Which of the AEDs is safest in pregnancy?
Carbamazepine, although there are still some risks.
Name some specific side effects of phenytoin.
- cleft lip and palate
- congenital heart defects
Which AED is a cardiac depressant and can cause arrhythmias?
Phenytoin
What drugs are given for the initial management of seizures?
Benzodiazepines e.g. Lorazepam or midazolam (given PR if pre-hospital and IV if in hospital).
What is SUDEP?
Sudden unexpected death in epilepsy
