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Flashcards in Epilepsy Deck (19)
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1
Q

Define seizure

A

Clinical manifestation of abnormally excessive & hyper synchronous activity of neurons located mainly in cerebral cortex

2
Q

How are seizures classified?

A
  • Generalized= initial activation of neurons throughout both hemispheres
  • Partial= initial activation of limited number of neurons in part of 1 hemisphere
  • Secondary generalized= partial seizure that spreads to involve majority of 2 cerebral hemispheres
3
Q

What are the manifestations of a partial seizure in the different lobes?

A
  • Frontal= Jacksonian seizure- tingling in hand/arm, adverse seizures- eyes/head turn to one side
  • Parietal= tingling/jerking of leg, arm, face
  • Occipital= flashing lights/spots, vomiting
  • Temporal= smell/taste, altered behaviour, deja vu, lip smacking, chewing movements
4
Q

What is status epilepticus?

A
  • Life threatening
  • Brain in state of persistent seizure= 30+mins OR 2+ without full recovery
  • Confers greater risk for future unprovoked seizures
5
Q

What is the mechanism of a seizure?

A
  • Excitation= ionic: Na+, Ca2+ influx, neurotransmitter: aspartate & glutamate release
  • Inhibition= Ionic: Cl-, K+ efflux, neurotransmitter: GABA release
  • Either can result in too much neuronal activity-seizure
  • Initially localised hyper excitability spreads to surrounding neuronal networks
  • Either inhibited or chain reaction-seizure
6
Q

What is the function of inhibitory interneurons?

A
  • Allow activity to spread in one direction but not sideways

- Release neurotransmitter GABA

7
Q

Describe GABA

A
  • γ-aminobutyric acid
  • Major inhibitory neurotransmitter
  • GABA(A)= ligand gated chloride channel receptor
  • GABA(B)= G protein-coupled receptor
8
Q

What types of epilepsy are caused by a mutation in GABA(A) receptor subunits?

A
  • Childhood absence epilepsy
  • Pure febrile seizures
  • Juvenile myoclonic epilepsy
  • Generalized epilepsy with febrile seizures
  • Dravet syndrome/ SMEI
9
Q

What are the modes of action for anti-epileptic drugs?

A
  • Suppress a.p= Na channel blocker, K channel opener
  • Enhance GABA transmission= GABA mimetics/uptake inhibitor
  • Suppression of excitatory transmission= glutamate receptor antagonist
10
Q

Name some Benzodiazepines and describe them

A
  • Clonazepam= generalized tonic-clonic, absence & partial seizures
  • Clorazepate= partial seizures
  • Diazepam/valium/lorazepam= SE given IV
11
Q

What is the mechanism of action for benzodiazepines

A
  • Inc affinity of GABA for receptor
  • Inc Cl- current
  • Suppresses seizure focus by raising ap threshold
  • Strengthens surrounding inhibition-prevents spread
12
Q

What are the negatives of using benzodiazepines?

A
  • Sedation major side effect
  • Problems with tolerance & dependance (avoid LT use)
  • Respiratoy depression in IV use
13
Q

What is the mechanism of action for Phenytoin?

A

-When Na+ channels inactivated after depolarisation it binds to receptor so slows down recovery

14
Q

Describe epilepsy & pregnancy

A
  • Very harmful to pregnant women
  • Folic acid recommended
  • Phenytoin/ valproic acid contraindicated
15
Q

What anti-epileptic drugs have mixed actions?

A
  • gabapentin

- valproate (valproic acid)= tonic-clonic & absence, also used in bipolar

16
Q

How does valproate work?

A
  • Inhibits Na+ channels
  • Dec GABA turnover
  • Blocks neurotransmitter release by blocking T-type Ca2+ channels
17
Q

What is foetal hydantoin syndrome?

A
  • Pregnant & taking Phenytoin
  • Intrauterine growth restriction- microcephaly
  • Minor dysmorphic craniofacial features & limb defects
  • Some have growth problems & developmental delay
18
Q

What is foetal Valproate syndrome?

A

-Congenital malformations in infants

19
Q

What is epilepsia partialis continua?

A
  • Rare brain disorder
  • Recurrent motor epileptic seizures- focal (face & hands)
  • Due to large, acute brain lesion= stroke in adults, focal cortical inflammatory processes in children
  • Medication & therapy resistant
  • Goal to stop secondary generalization