Epilepsy Flashcards
What factors should be considered when making a possible diagnosis of epilepsy
history from patient and witness aura/ warning abnormal movements colour position when after effects
what are the signs? what is the type of seizure?
what investigations should be done when making an epilepsy diagnosis
examination will often be normal
EEG, ECG, MRI
what is the difference between a partial and generalised seizure
partial seizure activity originates in one area of the brain and may be simple or complex
generalised seizures affect the whole brain(both hemispheres) and may be absent, myoclonic, tonic clonic, tonic, atonic
what are the features of a myoclonic seizure
a type of generalised seizure
the person is usually awake
brief shock like jerks of muscles
seen in a wide variety of seizures
what are the features of simple partial seizures
focal with minimal spread of abnormal discharge
normal consciousness
what are the features of complex partial seizures
local onset then spreads impaired consciousness often an aura automatisms motor activity
most commonly temporal lobe epilepsy
what are secondary generalised seizures
begin focally, with or without focal neurological symptoms
variable symmetry, intensity and duration of tonic-clonic phases
usually 1-2 minutes
postictal confusion and somnolence
what are the features of absence seizures
a type of generalised seizures sudden onset and abrupt cessation brief duration altered consciousness may be mild clonic jerking postural tone change autonomic features and automatisms
what is an atonic seizure
sudden loss of postural tone
often in children
what are the features of tonic clonic seizures
major convulsions with rigidity (tonic) and jerking (clonic)
followed by stuporous state- post ictal depression
what are the phases of generalised tonic clonic seizures
1) tonic phase, muscles tense up causing the person to fall to the ground
2) Muscles start to contract and relax rapidly- clonic phase
may also occur in partial seizures involving motor centres
what factors increase seizure risk
lack of sleep tiredness alcohol/ hangover certain drugs e.g. antidepressants fever structural brain abnormalities
what is status epilepticus
more than 30 minutes of seizure activity or multiple seizures in 30 minutes without full recovery in between
medical emergency
In what proportion of epileptics are medications effective at reducing seizure
60% become seizure free
20% are drastically reduced
what AEDs act primarily on sodium channels
phenytoin, carbamazepine, oxcarbazepine, zonisamide, lamotrigine
what is a partial seizure
confined to one lobe or hemisphere of the brain
what is a simple partial seizure
person remains conscious
may involve strange sensations or abnormal movements
what is a complex partial seizure
local onset, then spreads
impaired consciousness
aura
automatisms
person looses consciousness or regains consciousness slowly
what are the types of generalized seizures
absence myoclonic tonic clonic tonic clonic atonic
what are the types of partial seizure
simple partial
complex partial
what are the features of absence seizures
sudden onset and abrupt
cessation; brief duration, consciousness is altered; attack
may be associated with mild clonic jerking of the eyelids or
extremities, postural tone changes, autonomic phenomena
and automatisms (difficult diagnosis from partial);
characteristic 2.5-3.5 Hz spike-and wave pattern
what is a myoclonic seizure
myoclonic jerking is seen in a wide
variety of seizures but when this is the major seizure type it
is treated differently to some extent from partial leading to
generalized
what seizures are non convulsive
atonic and absence
what seizures may convulsions be seen in
simple and complex partial
generalised seizure
what is the function of antiepileptic drugs
treats the frequency and severity of seizures
they cannot stop the cause of seizures
what are the cellular mechanisms of seizure generation
EPSPs
sodium influx
calcium currents
paroxysmal depolarization
what are the cellular mechanisms of seizure control
IPSPs potassium efflux chloride influx pumps low pH
what are the targets for AEDs
increase inhibitory nt system -GABA
decrease excitatory NT system- glutamate
block voltage gated inwards positive currents of sodium or calcium
increase outward positive current of potassium
many are pleitropic
what is glutamate
major excitatory NT
what are the two types of glutamate receptors
ionotropic (fast synaptic transmission)
metabotropic (slow)
regulation of second messengers
What AEDs act primarily on sodium channels
phenytoin
carbamazepine
oxcarbazepine
zonisamide
lamotrigine
what are the current commonly used epilepsy drugs
lamotrigine sodium valproate carbamazepine oxcarbazepine levetiracetam topiramate
what are some older less used drugs
- phenytoin,
- ethosuxamide,
- phenobarbitone,
- vigabatrin,
- tiagabine
lamotrigine
inhibits sodium channels
broad therapeutic profile
side effect: skin rashes
sodium valproate
increase in GABA content
side effects: teratogenicity
liver damage
carbamazepine
tricyclic antidepressant derivative
used in partial seizures and trigeminal neuralgia
enzyme inducing agent so drug interactions
side effects: sedation, ataxia
oxcarbazepine
related to carbamazepine
partial seizures
sedating but less toxic
levetiracetam
inhibits Ca
partial and general seizures
psychiatric side effects
topiramate
not well understood
teratogenesis
tiagabine
gaba uptake inhibitor
partial seizures
zonisamide
blocks sodium channels
phenytoin
blocks sodium channels
not effective in absence seizures
common drug interactions
and side effects :confusion, gum hyperplasia, skin rashes,
anaemia, teratogenesis, cerebellar syndrome, osteoporosis
also an antidysrhythmic
ethosuximide
absence seizures in children
blocks calcium channels
few side effects
phenobarbitone
rare
long half life
osteoporosis
benzodiazepines
status epilecticus (IV) sedating
felbamate
unknown moa
limited to otherwise untreatable and severe disease
vigabatrin
inhibits GABA transaminase
for pts unresponsive to other drugs, rare
side effects: drowsiness, behavioural and mood changes
gabapentin/ pregabalin
calcium channels
inhibits NT release
add on therapy for partial seizures and tonic clonic
less sedating than classic AEDs
used in neuropathic pain
when is neurosurgery indicated for epilepsy
partial seizures usually
when you’ve tried at least 3 drugs
electrophysiology
functional MRI
baclofen
agonist for GABA receptors
action exerted at level of spinal cord
used for spasticity from MS or spinal injury
not used in epilepsy
what is the main difference between a simple and complex partial seizure
simple seizures do not involve a reduction or alteration in consciousness
a simple partial may be an aura to a complex or generalised seizure
what is NMDA
a glutamate receptor which allows positively charged ions to flow into the cell
what is the treatment for status epilepticus
diazepam, lorazapam IV
phenytoin, fosphenytoin or phenobarbitol
what epilepsy drugs are commonly used in children
valproate
lamotrigine
levetricetam
ethosuxamide
