Anti Epileptic Flashcards
What is a seizure
sudden irregular discharge of electrical activity in the brain causing a physical manifestation such as sensory disturbance, unconsciousness or convulsions
What is a convulsion
uncontrolled shaking movements of the body due to rapid and repeated contraction and relaxation of muscles
What is an aura
a perceptual disturbance experienced by some prior to a seizure, e.g. strange light, unpleasant smell, confusing thoughts
What is epilepsy
neurological disorder marked by sudden recurrent episodes of sensory disturbance, LOC or convulsions, associated with abnormal electrical activity in the brain
What is status epilepticus
epileptic seizures occurring continuously without recovery of consciousness in between
How can seizures be classified
-
Compare partial vs generalised seizures
Partial happens in a single focus - one part of the brain. Generalised - seizure all over the brain - might start as a focus nd the spread uncontrolled throughout the brain
What are partia lseizures
PARTIAL SEIZURES • Part of the brain
• Simple or complex – Simple = Same consciousness - no loc
– Complex —> COnsciousness is iMPaired - loc
What are common types of partial seizures
• Temporal lobe epilepsy
– 1st/2nd decade in most people, following seizure with fever or an early injury to the brain
– auras –e.g. auditory hallucination, rush of memories
• Frontal lobe epilepsy – next most common
- Abnormal movements when motor areas affected (contralateral side)
What are types of generalised seizures
- Tonic-clonic: 2 parts - 1st tonic (muscles Tense), 2nd clonic (Convulsions)
- Absence:‘daydreaming’
- Statusepilepticus:medicalemergency
- Myoclonic:briefshock-likemusclejerks
- Atonic:‘without tone’ – drop attack
- Tonic:increasedtone
What are the vestigatins to confirm/exclude diagnosis
INVESTIGATIONS
• Clinical history • EEG
• MRI
• (ECG,bloods)
What should be asked about when asking a history abt seizure
Before
- pmh, fh
- triggers
- auras
- first sign/symptoms
During
- description of seizure
- duration
- abrupt or gradual Ed
After
- post-coal state
- tongue biting
- incontnence
- neurological defecit
Vial to take collateral history where possible
What are causes of epilepsy
• Can be primary or secondary • Primary (idiopathic) – No apparent cause – May be inherited • Secondary (symptomatic) – Known cause for epilepsy
- Vascular:Stroke,TIA
- Infection: Abscess, Meningitis
- Trauma:Intracerebralhaemorrhage
- Autoimmune:SLE
- Metabolic:Hypoxia,Electrolyteimbalance, Hypoglycaemia,Thyroid dysfunction
- Iatrogenic: Drugs, Alcohol Withdrawal
- Neoplastic:Intracerebralmass
What is an eeg
EEG
• EEG not diagnostic - supports diagnosis
• In first unprovoked seizure – assess risk of seizure recurrence (unequivocal epileptiform
activity on EEG)
• Standard EEG assessment involves photic stimulation and hyperventilation - patient warned that it may induce a seizure
• Do NOT use if:
– Probable syncope (risk of false positive result)
– Clinical presentation supports diagnosis of non-epileptic event – In isolation to make a diagnosis of epilepsy
• Ifunclear,consider:
– Repeated standard EEGs
– Sleep EEGs (sleep deprivation or melatonin in children/young people) – Long-term video or ambulatory EEG
What are other investigations
OTHER INVESTIGATIONS
• To exclude other suspected causes of seizure • ECG as standard in adults
• MRI – in all patients with new-onset seizures
What are some classes of anti epileptic drugs
- Na channel blockers • GABA potentiators • Ca channel blockers
- Other drugs affecting GABA • Levetiracetam
How to Na+ channels work and what are some examples
• Cause Na channels to remain in an inactive state • Prevent axons from firing repetitively • Examples – Carbamazepine – Phenytoin – Lamotrigine – Sodium valproate – Topiramate
What are ccbs and how do they work
CALCIUM CHANNEL BLOCKERS • Prevent activity of Ca channels • Prevent depolarisation causing “spike and wave” discharge • Used in absence seizures • Examples – Ethosuximide – Sodium valproate
What are gaba potentiators and gaba
• GABA = inhibitory neurotransmitter, so rapidly alters excitability • Involved with neurotransmitter modulation in a third of brain impulses • GABA potentiators enhance the effect of GABA at the synaptic junction – Examples • Barbiturates (Phenobarbital) • Benzodiazepines (Midazolam) • GABA-transaminase inhibitors – Prevent breakdown of GABA – Vigabatrin • Increased GABA production – Improve utilisation of glutamate – Gabapentin
What is levetiracetam
• Trade name Keppra
• Binds to synaptic vesicles (SV2A glycoprotein)
to inhibit pre-synaptic calcium channel activity
• Therefore, inhibiting neurotransmitterrelease from the pre-synaptic neuron
When would antiepileptic be considered for use
• Epilepsy specialist/neurologist once diagnosis confirmed
• Considered if first unprovoked seizure and…
– Neurological deficit
– EEG shows unequivocal epileptic activity
– Risk of a further seizure is unacceptable
– Imaging reveals a structural abnormality
• Take into account the seizure type, patient’s age, lifestyle and preferences
How are antiepileptics initiated
• Start with monotherapy and if ineffective change to monotherapy with different AED
• First-line for generalised or tonic-clonic seizures – sodium valproate (or lamotrigine)
– If ineffective, other adjuncts considered (e.g. Levetiracetam, topiramate or sodium valproate AND lamotrigine)
• Titrate up to achieve a balance of therapeutic effect vs adverse side effects
What are ways anti epileptics can interact with other drugs
• Beware of interactions – Liver enzyme inducers • Carbamazepine • Phenyotin – Liver enzyme inhibitors • Sodium valproate
What are some side effects of aeds
Ss
Why may aeds be changed
• Change if unacceptable side effects, failure of treatment or on inappropriate drug
• Start at initial dose and slowly increase to middle of recommended therapeutic range
• Then slowly withdraw old drug over about 6 weeks
Keep patient on the drug, start a new one, slowly titrations up until middle of therapeutic range, then take the old one away. Want them to overlap - initial one may have had some kind of effect
When might aeds be stopped
• Consider if patient seizure free for at least 2 years
– 60% will have no further seizure when medication withdrawn
• However, bear in mind the increased risk of seizure compared to those who continue on treatment
– Epilepsy since childhood
– Patients on more than one drug
– Myoclonic or tonic-clonic seizures – Abnormal EEG in last year
– Known underlying brain damage
• Need to think about patient’s livelihood
• DVLA recommends no driving for 6 months after stopping medication
How are aeds stopped
CESSATION OF ANTIEPILEPTICS
• Gradually taper off
• Aim is to avoid withdrawal features – Recurrent seizures
– Anxiety and restlessness
• Lamotrigine, carbamazepine, phenytoin, sodiumvalproate, vigabatrin – Reduce dose by 10% every 2-4 weeks
• Ethosuximide, barbiturates, benzodiazepines – Reduce dose by 10% every 4-8 weeks
• If on more than one drug, withdraw from one drug at a time
– 1 month between complete withdrawal from one drug and starting withdrawal from another
What are the effects of some aeds in pregancy
• Risk of congenital malformations
– E.g.neuraltubedefects, hypospadias, cardiacdefects
• Carbamazepine
– Generally perceived as safe in pregnancy, although still carries risks
• Sodium Valproate
– Thought to cause decreased serum folate -> neural tube defects
– Craniofacial and skeletal abnormalities
– Developmental disorders after birth (mental and physical)
• Try not to prescribe sodium valproate to females of childbearing age
• Prescribe lowest effective dose
– Divided over the day
– Controlled-release tablets
• Start folate supplementation before pregnancy
• If no suitable alternative, counsel on risks and appropriate contraception
• Specialist prenatal monitoring
What are the effects of phenytoin
PHENYTOIN • Common congenital malformations – Cleft lip and palate – Congenital heart defects (septal defects) • Anticonvulsant (epilepsy) • Cardiac depressant (arrhythmias) • Levels peak at 3 – 9 hours post dose • Therapeuticlevels:10mg/l–20mg/l • Toxicity nausea, CNS dysfunction (confusion, nystagmus, ataxia), decreased consciousness, coma!
Describe teh pk of phenytoin
• Narrow therapeutic window
• Non-linear pharmacokinetics
• Therapeutic drug monitoring to:
– Establish individual therapeutic concentration
– Aid diagnosis of clinical toxicity
– Assess compliance
– Guide dose adjustments in patients with greater pharmacokinetic variability
• Following loading dose, checked at 3-4 days, then 3-12 monthly if stable
What are treatments for partial seizures
Treatment of partial seizures (simple & complex)
• Lamb
– Lamotrigine
• Top
– Topiramate: can’t be explained off the Top a Ma Head
– Also used in migraines
• Gave
– Gabapentin: wishes it worked like GABA but has pent up frustration
• Funny
– Phenytoin: can’t be funny for too long, so use in Status Epilepticus
• Carbs
– Carbamazepine: keeps Na channels inactive like phenytoin
What are the treatment of general seizures
eneral seizures:
• Barbara
– PheNObarbitol: NO barb means don’t use unless desperate
• Valiantly
– Sodium valproate: valiantly tries to do many things (including “attacking the liver enzymes”)
• Sux
– Ethosuximide: Sucks to learn it, but make sure it doesn’t go absent from revision
• Good-Pam
– Ends in Pam, so it’s a benzo
– Acts quickly, so it’s good 1st line for status epilepticus
Describe the initial management of seizures
ABCDE -> lorazepam or midazolam benzodiazepines)
Pre-hospital: PR or buccal Hospital: IV
What is status epilepticus
= epileptic seizures occurring continuously without recovery of consciousness in between
Neither Funny nor Good
So use Phenytoin or Benzodiazepines
What is first fit c.liic
• Following first seizure, patient deemed safe for discharge • Referral to First Fit Clinic follows
• Advise patient of lifestyle changes in the meantime
• If treatment initiated:
AIM = CONTROL of seizures on FEWEST drugs with LOWEST dose and LEAST side effects
What are daily living considerations
• Driving:
– Epilepsy when awake, licence is taken away until 1 year seizure-free
– If due to medication change: 6 months seizure-free
– Seizures whilst asleep or don’t affect driving or consciousness – assessment of case by DVLA
– If one-off seizure then can apply when 6 months seizure-free and assessment by DVLA
• Do not operate dangerous machinery
• Avoid potentially dangerous work or activities, e.g. swimming, climbing ladders
• Bathe with supervision or leave bathroom door unlocked
• Do not bathe babies alone
• Do not cycle on busy roads
• Avoid consuming alcohol
What are the long term considerations
• Annual review
– Check seizure control and if any precipitants
– Compliance
– Consider advice on contraception, pregnancy, employment issues and benefits
• SUDEP (sudden unexpected death in epilepsy)
– Increased risk in patient with uncontrolled seizures
– Risk increases to 1 in 150 with poorly controlled seizures
• Increased risk of mental health illness
– Abnormal activity of neurotransmitters – Structural abnormalities
– Functional abnormalities
