what is the definition of a seizure?
why does a seizure occur?
a transient occurrence of signs and symptoms that are due to abnormal electrical activity in the brain leading to disturbances of consciousness, behaviour, emotion, motor function and sensation
when the inhibitory and excitatory neurones are out of balance (glutamate NMDA and GABA via GABAa R)
there is abnormal excessive exception due to loss of inhibitory GABA or too much excitatory glutamate
can occur at any pint in the brain and the localised changes result in generalised effects
what can cause the imbalance of excitation and inhibition in a seizure?
- genetics
- exogenous activation e..g drugs
- aired changes in brain chemistry e.g. withdrawal or metabolic changes - low glucose
- damage to any f the networks e.g. stroke or tumor
symtpoms and signs of seizure?
what is the definition of epilepsy ?
why is making a diagnosis done by a specialist?
a tendency towards recurrent seizures unprovoked by a systemic or neurological insult
at least 2 unprovoked seizures occurring more than 24 hour apart
the diagnosis can be life changing e.g. no driving !!
what is a reflex seizure ?
examples of causes?
a seizure brought on by a particular stimulus
- phtotgenic
- thinking
- eating
- hot water immersion
- reading
- organsm
- movement
what ate the 3 broad classifications of seizure
in what one are you aware?
examples of each?
what is the definition of a generalised seizure?
what is a focal seizure?
a seizure that originated in one location then rapidly spreads to involve both hemispheres
originated in networks limited to 1 hemisphere
what is a provoked seizure?
a seizure as a result of another medical condition e.g. drug withdrawal or use, head trauma, metabolic disturbances (hyponatraemia and glycaemia), febrile seizure, uncontrolled hypertension
treat seizure and treat underlying cause !1
what are some differentials for a seizure?
what is status epilepticus?
a seizure lasting more than 5 mine (therefore needing medication) or multiple seizures without complete recovery between
it is an emergency
what is the pharmacological treatment of a seizure?
how do benzodiazepines work?
what are the issues with them?
other uses?
examples and how they are administered?
GABAa agonist
increase Cl- conductance making IPSP and works best when mrmrabe is positive e.g. during a seizure
addiction, CVA collapse and airway issues
anxiolytics, sleep aids, alchohol withdrawal
IV lorazepam
rectal diazepam
buccal or intranasal midazolam
what investigations can help aid epilepsy diagnosis ?
EEG
MRI - detects vascular or structural abnormalities hat can account for epilepsy
what are the anti-epileptic drugs I should know?
AED
how does carbamazepine work?
what is it used for?
side effects?
Na+ channel blocker
epilepsy, bipolar, chronic pain
suicidal thoughts, joint pain, bone marrow failure e.g. neutropenia and aplastic anaemia
AEDs
how does phenytoin work?
what is it used for?
side effects?
Na+ channel blocker
status epilepticus, or add on in generalised seizures
0 order kinetic therefore be wary with dosing
bone marrow suppression, hypotension, arrhythmias
AEDs
how does sodium valproate work?
what is it used for?
side effects?
Na+ channel bloacker and GABAa agonist
1st line for generalised epilepsy !!
liver failure, pancreatitis, lethargy
AED
how does lamotrigine work?
what is it used for?
Na+ channel blocker and effects Ca channels too ! act to hyperpoalrise cell
good for focal epilepsy and used when valproate is contraindicated in vernalised epilepsy
AEDs
how does levetiracetam work?
when is it used?
why is it good?
synaptic vesicle glycoprotein binder therefore stops release of neurotransmitter into synapse
option for focal and generalised seizures
easy dosing, well tolerated, safe in pregnancy !
what are side effects of all AEDs?
what are some interactions for AEDs?
- warfarin need to be monitored
- no alchohol
- carbamazepine and phenytoin decrease oral contraceptive effect
- carbamazepine and phenytoin decrease antibiotics
- valporate increases other AEDs
what are the AEDs that a re inducers of CYP?
inhibitors?
inducers = Phenytoin, carbamazepine, barbiturates
inhibitor = valproate
how to start someone on AEDs
family planning
epilepsy and driving