Epilepsy Flashcards
What is a seizure?
A sudden, irregular discharge of electrical activity in the brain causing a physical manifestation such as sensory disturbance, unconsciousness or convulsions
What are convulsions?
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
What are the classifications of seizures?
Partial - simple or complex
Generalised - absence, myoclonic, tonic-clonic, tonic, atonic
What is the difference between a simple or a complex seizure?
Simple - same consciousness
Complex - Consciousness is impaired
What different types of epilepsy can cause partial seizures?
Temporal lobe epilepsy - 1st/2nd decade in most people, following seizures with fever oran early injury to the brain.
Aura’s - e.g. auditory hallucinations, rush of memories
Frontal lobe epilepsy - next most common
Abnormal movements when motor areas affected (contralateral side)
What are the different types of generalised seizures?
Tonic-clonic: tonic = muscles tense, clonic - convulsions
Absence: ‘daydreaming’
Status epilepticus: medical emergency
Myoclonic: brief shock-like muscle jerks
Atonic: ‘without tone’ - drop attack
Tonic: increased tone
What investigations do you do for seizures?
Clinical history
EEG
MRI
ECG, bloods
What things do you ask about in a clinical history?
Before - PMH, FH, triggers, aura, first sign / symptoms
During - description of seizures, duration, abrupt/gradual end
After - post-ictal state, tongue biting, incontinence, neurological deficit.
What is the difference between primary and secondary epilepsy?
Primary (idiopathic)- no apparent cause, may be inherited
Secondary (symptomatic)- known cause
What are some possible causes of epilepsy?
Vascular: Stroke, TIA Infection: Abscess, Meningits Trauma: Intracerebral haemorrhage Autoimmune: SLE Metabolic: hypoxia, electrolyte imbalance, hypoglycaemia, thyroid dysfunction Iatrogenic: drugs, alcohol, withdrawal Neoplastic: Intracerebral mass
Why is EEG used?
EEG supports diagnosis - not diagnostic
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
When do you not use EEGs?
Probable sincope (risk of false positive)
Clinical presentation supports diagnosis of non-epileptic event
In isolation to make a diagnosis of epilepsy
What do you go if EEG is unclear?
Repeat standard EEGs
Sleep EEGs (sleep deprivation or melatonin in children / young people)
Long term video or ambulatory EEG
What anti-epileptic drugs are there?
Na channel blockers
GABA potentiators
Ca channel blockers
Other drugs affecting GABA:
Levetiracetam
What do Na channel blockers do?
Cause Na channels to remain in an inactive state
They prevent axons from firing repetitively.
Give examples of Na channel blockers?
Carbamazepine Phenytoin Lamotrtrigene Sodium valproate Topiramate
What are Ca channel blockers and when are they used?
Prevent activity of Ca channels
Prevent depolarisation causing “spike and wave” discharge.
Used in absence seizures
Give examples of Ca channel blockers
Ethosuximide
Sodium valproate
What are GABA potentiators? (give examples)
They enhance the effect of GABA at the synaptic junction
For example:
Barbituates (phenobarbartal)
Benzodiazepines (Midazolam)
What are GABA-transaminase inhibitors? (Give examples)
Prevent the breakdown of GABA
e.g. Vigabatrin
Why increase GABA production?
To improve the utilisation of glutamate.
For example: Gabapentin
What is levetiracetam?
Trade name: Keppra
Binds to synaptic vesicles to inhibit pre-synaptic calcium channel activity.
Therefore, inhibiting neurotransmitter release from the pre-synaptic neurone
When do you initiate anti-epileptics?
When an epilepsy specialist / neurologist confirms diagnosis (usually after more than one seizure)
Consider if first unprovoked seizure and…
Neurological deficit
EEG shows unequivocal epileptic activity
Risk of a further seizure is unacceptable
Imaging reveals a structural abnormality
What do you start with when starting anti epileptics?
Start with monotherapy and if ineffective change to mono therapy with different AED
First line for generalised or tonic-clonic seizures - sodium valproate (or Iamotrigine)
-If ineffective, other adjuncts considered
Titrate up to achieve a balance of therapeutic effect vs adverse side effects
What interactions do you have to be aware of?
Liver enzyme inducers: Carbamazine, phenytoin
Liver enzyme inhibitors: Sodium valproate
What are the adverse effects of anti-epileptics?
All: Dizziness, Fatigue, Ataxia, Diplopia
Irritability, behaviour changes Weight loss / anorexia Weight gain Tics and insomnia Metabolic acidosis Language dysfunction
How do you change anti-epileptics?
Start at initial dose and slowly increase to middle of recommended therapeutic range.
Then, slowly withdraw old drug over about 6 weeks.
Change if unacceptable side effects, failure of treatment or on inappropriate drug.
What patients have an increased risk of seizure if treatment is withdrawn?
Epilepsy since childhood Patients on more than one drug Myoclonic or tonic-clonic seizures Abnormal EEG in last year Known underlying brain damage
How do you stop anti epileptics?
Gradually taper off
Aim is to avoid withdrawal features such as recurrent seizuresand anxiety and restlessness.
Reduce rates of ethosuximide, barbiturates and benzodiazepines more slowly.
What anti-epileptic drug is safe in pregnancy?
Carbamazepine
What anti-epileptic drugs is bad in pregnancy? Why?
Sodium Valproate
Thought to cause decreased serum folate - neural tube defects.
Cranio-facial and skeletal abnormalities.
Developmental disorders after brith.
If have to describe, use lowest effective dose
Start folate before pregnancy.
Have specialist prenatal monitoring
What are the side effects of phenytoin?
Common congenital malformations - cleft lip and congenital heart defects (septal defects).
Anticonvulsant (epilepsy)
Cardiac depressant (arrhythmias)
What does phenytoin require therapeutic monitoring?
Because it has a narrow therapeutic window and non-linear pharmacokinetics.
Toxicity = nausea, CNS dysfunction, decreased consciousness, coma.
Monitoring to:
- Establish individual therapeutic concentration
- Aid diagnosis of clinical toxicity
- Assess compliance
- Guide dose adjustments in patients with greater pharmacokinetic variability
What is the pneumonic to remember the treatment of partial seizures?
LAMB TOP GAVE FUNNY CARBS
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 is the pneumonic to remember the treatment of general seizures?
BARBARA VALIANTLY SUX GOOD-PAM
Barbra: pheNOcarbitol: NO barb mena dont use unless desperate
Valiantly: Sodium Valproate: valiantly tries to do many things (inc attacking liver enzymes)
Sux: Ethosuximide: sucks to learn it; but make sure it doesn’t go absent from revision
Good-Pam: ends in pam, so its a benzo. Act’s quickly so its good 1st line for status epilepticus
How do you initially manage seizures?
ABCDE
Lorazepam or Midazolam
Pre-hospital: PR or buccal
Hospital: IV
What is status epilepticus?
Epileptic seizures occurring continuously without recovery
Neither funny nor good
So used benzodiazepines
or phenytoin.
What is the first fit clinic?
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 to control seizures with the lowest dose and least side effects.
What daily living considerations are there, within epilepsy?
Driving: licence is taken away until seizure free for a while
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 long term considerations are there with epilepsy?
Annual review: check compliance, seizure control, advise on contraception, pregnancy, employment issues, benefits.
SUDEP (sudden, unexpected detain epilepsy): Increased risk of uncontrolled seizures (to 1 in 150)
Increased his of mental health illness: abnormal activity of neurotransmitters, structural abnormalities, functions abnormalities.
