epilepsy Flashcards
what counts as status epilepticus
Seizures which last more than 5 minutes (or more than one seizure in 5 min, without regain of consciousness)
other name for grand mal seizure
tonic-clonic seizure
what is tonic, what is clonic
tonic is tightening of muslces, eyes drifting upwards. clonic is jerking mvts and possible sphincter opening
what are the 5 stages of a tonic-clonic seizure
Premonition (‘aura’ - a vague sense that a seizure is imminent; changes in sensation, intense emotion, mood change)
Pre-tonic-clonic phase (a few myoclonic jerks or brief clonic seizures)
Tonic phase (tonic contraction of the axial musculature; upward eye deviation and pupillary dilatation; tonic contraction of the limbs; cyanosis; respiratory muscle contraction - “epileptic cry”; tonic contraction of jaw muscles)
Clonic phase - jerks of increasing amplitude followed by relaxation (sphincter opening may occur)
Postictal period (generalized lethargy; decreased muscle tone, headaches, muscle soreness)
epilepsy diagnosis
2 or more seizures more than 24h apart
EEG between seizures looks
normal
2 examples of structural changes in epilepsy
mossy fibres sprouting leads to aberrant pathways
loss of chandelier cells (GABAergic) leads to loss of inhibition
where do chandelier cells have their effect
axon initial segmnet
which receptors are involved in burst firing neurones in epilepsy
NMDA
why would astrocyte deficiency/malfunction cause epilepsy
astrocytes clear up glutamate from synapse after action potential through EAAT1 and 2. Too much glutamate left hanging about can lead to aberrant action potentials
which neurones are most involved in epilepsy
interneurones
what is mTOR pathway
regulattor of growth and homeostasis - protein synthesis
what is REST pathway- what conditions
leads to negative regulation
of the expression of many genes in the CNS
global ischemia, stroke, epilepsy, Alzheimer’s and Huntington’s disease.
what do you need to think about re pharmacokinetics phenytoin, carbemazepine
CYP450 enhancer, so other drugs pt is on will be eliminated faster - less effective
sodium channel antiepileptics
Phenytoin
Leads - lamotrigine
To - Topiramate
Less - lacosamide
Sodium - sodium valproate
Channel - carbemazapine
Zoom - zonisamide
valproate age restric
no under 55 women unless 2 consultants agree no other effective option
which antiepileptics target Ca channel. which sub-unit
Ethosuximide (used in absence seizures, targets T-type calcium channels)
Gabapentin and pregabalin (alpha2delta subunit of calcium channels; also enhanced GABA synthesis)
benzo ending and mia
zepam GABA A receptor allosteric agonist
What ion is transported in GABA channel
Cl-
epileptic neuro transmitter drugs
Neurotransmitter release
Levetiracetam (protein SV2A; modulates neurotransmitter release)
Neurotransmitter uptake
Tiagabine (GAT-1 transporter)
Neurotransmitter metabolism
Vigabatrin (inhibition of GABA transaminase)
Neurotransmitter receptors
Perampanel (selective non-competitive antagonist of AMPA receptors)
Felbamate (NMDA receptors; also GABAA receptors?)
tx status epilepticus
Benzodiazepines (buccal midazolam or rectal diazepam) are recommended by NICE as the first-line treatment for patients without intravenous access. If intravenous access were available, lorazepam would be the drug of choice.
