EPILEPSY Flashcards
seizures
a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain
some seizures can hardly noticed, while others are totally disabling. generally depends on area of the brain in which the seizure occurs
epilepsy
- at least 2 unprovoked (or reflex) seizures occurring >24h apart
- one unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after 2 unprovoked seizures, occurring over the next 10 years
- diagnosis of epilepsy syndrome
generalised seizures
arising within and rapidly engaging bilaterally distributed networks
(affects both hemispheres of the brain)
name all the generalised seizures (6)
- tonic-clonic
- absence
- clonic
- atonic
- myoclonic
tonic seizures
cause all of your muscle to suddenly become stiff
you can lose balance and fall over
absence seizures
- when you lose awareness of your surroundings for a short time
- mainly affect children but can happen at any age
- during the seizure the person may stare into space, flutter their eyes or make slight jerking movements
- the seizure only lasts up to 15 seconds and you won’t be able to remember them
- can happen several times a day
myoclonic seizures
- where some or all of your body suddenly twitches or jerks, often happen soon after waking up
- usually last only a fraction of a second, but can occur several times.
- you normally remain awake
atonic seizures
cause all your muscles to suddenly relax, so you may fall to the ground
clonic seizures
cause the body to shake and jerk but not stiff (like muscle spasms)
typically last a few minutes and you might lose consciousness
tonic-clonic seizures
happens in 2 stages
1. tonic stage - you lose consciousness and body goes stiff
2. clonic stage - limbs jerk about, may lose control of bladder or bowel, might bite your tongue or the inside of your cheek, might have difficulty breathing
long-term consequences of status epilepticus
neuronal death
neuronal injury
alteration of neuronal networks
status epilepticus
condition resulting from either the failure of the mechanisms responsible for seizure termination or from the initiation of mechanisms which lead to abnormally prolonged seizures
symptoms of a simple partial (focal) seizure or ‘auras’
can cause
- general strange feeling
- ‘rising’ feeling in tummy
- deja vu
- unusual smells/tastes
- tingling in your arms or legs
- stiffness or twitching in part of the body (arm or hand)
simple partial (focal) seizures or ‘auras’
known as ‘warnings’ or ‘auras’ because they can be a sign that another type of seizure is about to happen
you remain awake and aware
complex partial (focal) seizures symptoms
- smacking your lips
- rubbing your hands
- making random noises
- moving your arms around
- pick/fiddling
- chewing or wallowing
you lose your sense of awareness and make random body movements
you will not have any memory of it
focal seizures
originating in networks limited to one hemisphere
may develop into bilateral convulsive seizures
what causes epilepsy
- genetic (Dravet’s syndrome - SCN1a)
- structural (acquired or genetic)
- metabolic (glucose transporter deficiency GLUT1)
- immune (Rasmussen syndrome - autoimmune)
- infectious (bacterial and viral encephalitis)
- unknown (1/3 of all diagnosed)
co-morbidities associated with epilepsy
stroke
migraine/headaches
dementia
traumatic brain injury
cerebral palsy
ASD
MS
stage 1 - seizure sequence and underlying mechanism of epilepsy
initiation - abnormal voltage-gated channels
stage 2 - seizure sequence and underlying mechanism of epilepsy
synchronisation - abnormal receptor-operated channels
stage 3 - seizure sequence and underlying mechanism of epilepsy
propagation - recruitment of neurones via anatomical connections
targets for the treatment of epilepsy
- inihibition of voltage-gated Na+ channels
- promote inhibitory neurotransmission
- inhibition of voltage-gated Ca2+ channels
drugs that inhibit voltage-gated sodium channels
phenytoin
carbamazepine
lamotrigine (Also HVA Ca2+ channels)
oxcarbazepine
drugs that enhance GABA action
BZs - increase the frequency of opening of GABA A channels
phenobarbital - increase the probability of opening of GABA A channels
vigabatrin and tiagabine - inhibits GABA transaminase
drugs that inhibit voltage gated calcium channels
ethosuximide (T-type Ca2+ channels - LVA)
pregabalin (HVA Ca2+ channels)
gabapentin (HVA Ca2+ channels)
treating generalised seizures
1st line - sodium valproate
alternative - lamotrigine, topiramate
contraindications - Valproate & pregnancy
treating focal seizures
1st line - lamotrigine
alternative - carbamazepine, levetiracetam
contraindications - patient dependent side effects
treating absence seizures
1st line - ethosuximide
alternative - sodium valproate, lamotrigine
contraindications - patient dependent side effects
treating status epilepticus
1st line - midazolam ducally or intranasally
alternative - lorazepam, diazepam
contraindications - patient dependent side effects
what mechanisms does sodium valproate act on
Ca2+ channels
Na+ channels
GABA
what mechanisms does levetiracetam act on
Ca2+ channels
GABA
synaptic vesicle release
what mechanisms does felbamate act on
Ca2+ channels
Na+ channels
GABA
glutamate receptors
what mechanisms does perampanel act on
glutamate receptors (AMPA)
