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 is a convulsion?
Motor signs of electrical discharge.
Uncontrolled shaking movements of the body due to rapid contraction and relaxation of muscles
What is epilepsy?
A neurological disorder marked by sudden, recurrent episodes of sensory disturbance, LOC or convulsions associated with abnormal electrical activity in the brain
What are the two main seizure classifications?
Partial and generalised
Describe partial (focal) seizures
Start in a specific area on one side of the brain.
SIMPLE: consciousness maintained
- with focal motor, sensory, autonomic or psychic symptoms. No post ictal symptoms
COMPLEX: consciousness impaired
- May have a LOC or impaired awareness or responsiveness (don’t remember having seizure)
- Most commonly arise from temporal lobe
- Post ictal confusion is a feature
What symptoms are common in a temporal lobe seizure?
Feeling of deja vu Jamais vu - feeling of unfamiliarity Automatisms- complex motor phenomena with impaired awareness, vary from: lip smacking, chewing, swallowing or manual movements such as fiddling or grabbing, to complex actions Dysphasia Emotional disturbance- sudden terror, panic, anger, elation Hallucinations of smell, taste, sound Delusional behaviour Bizarre associations
What are secondary generalised seizures?
In 2/3 of patients with partial seizures, the electrical disturbance that starts focally spreads widely -> generalised seizure
Describe generalised seizures
Originate at some point within then rapidly distribute bilaterally leading to widespread electrical discharge with no localising features.
What types of generalised seizures are there?
Tonic clonic Tonic Myoclonic Atonic Absence
Describe a tonic clonic seizure
Muscle tense (tonic) then jerk (clonic) Described as rhythmic jerking Tonic phase: - 10 to 60 sec - rigid, epileptic cry, tongue biting, incontinence, hypoxia/cyanosis (no breathing in this phase)
Clonic phase:
- jerking
- eye rolling, tachycardia, random breathing
Often aura before
Afterwards post ictal state - confused, drowsy, headache, some enter coma
What is a tonic seizure
When the muscles increase in tone
What is a myoclonic seizure?
Sudden jerk of limb, face or trunk - shock like.
Patient may be thrown to ground or violently disobedient limb
What is an atonic seizure?
Sudden loss of muscle tone - drop attack
What is an absence seizure?
Brief < 10 second pauses, stop and carry on as if nothing happened
Unresponsive to stimuli but conscious
Patient stares, may go pale
Complete recovery without post ictal confusion or headache
When do absence seizures present?
In childhood
Likely to develop tonic clonic later in life
40% have relatives with epilepsy
Some patients experience a preceding prodrome before having a seizure. What is this characterised by?
Change in mood or behaviour
Can last from hours to days
Epilepsy most commonly occurs in isolation, but certain conditions are associated with it such as…
Cerebral palsy - 30% have epilepsy
Tuberous sclerosis
Mitochondrial diseases
When do febrile convulsions typically occur?
In children between 6 months and 5 years
Early in a viral infection as temperature rises rapidly
Typically brief and generalised tonic of tonic-clonic
What is an aura?
A focal awareness seizure that can precede another seizure type.
Usually occurs a few minutes before.
Sensory disturbances
An aura can mean what symptoms ?
Feeling of deja vu Flashing lights Strange smell or taste Numbness or tingling Strange feeling in the gut
Can be any sensation
What can happen during a seizure?
Tongue biting
Incontinence
What can happen post ictally?
Confusion Headache Nausea Fatigue Myalgia
Weakness after focal seizure in motor cortex (Todd’s palsy)
Dysphasia after focal seizure in temporal lobe
In those with epilepsy, the seizure threshold is said to be…
Lowered - neurons are hyperexcitable
What triggers can push neuron excitation past the seizure threshold?
Sleep deprivation
Alcohol - intake and withdrawal
Drug misuse
Flickering lights
CNS Infection
Metabolic disturbance e.g hypoglycaemia, hypoxia, thyroid dysfunction, electrolyte imbalance e.g hypocalcaemia
Less common: loud noises, hot bath, strange smells and sounds
All people who have had a seizure should be referred to a neurologist and seen within how many weeks?
2 weeks
How is epilepsy diagnosed?
Thorough history - collateral important
Establish type
Rule out provoking causes - most people would have a seizure given sufficient provocation, but not classified as epileptic
What investigations should be done?
EEG - not to diagnose, but can support it ECG - cardiac cause of syncope MRI - structural lesions Drug screen LP if infection suspected Bloods
Until diagnosis known, what should be avoided?
Swimming
Heights
Driving
How long should driving be stopped for after having seizure?
First unprovoked/ isolated seizure : 6 months off if no structural abnormalities on imaging and no definite epileptiform activity on ECG
If these conditions not met this is increased to 12 months
If established epilepsy or multiple unprovoked seizures - may qualify for driving licence if free from seizure for 12 months
Withdrawal of epilepsy medication-should not drive for 6 months after last dose
When should anti epileptic drugs be commenced?
Most neurologists start AEDs following second epileptic seizure
NICE suggests starting them after first seizure if:
- a neurological deficit
- brain imaging shows structural abnormality
- EEG show unequivocal epileptic activity
- patient of family consider risk of having further seizure unacceptable
What are some differentials?
Vascular: stroke Infection: abscess, meningitis Trauma: intracerebral haemorrhage Autoimmune: SLE Metabolic: hypoxia, electrolyte imbalance, hypoglycaemia, thyroid dysfunction Iatrogenic: drugs, alcohol Neoplastic: intracerebral mass
If seizure is due to mediation change, how long can patient not drive for?
Need to be 6 months seizure free
What drug is first line for generalised seizures?
Sodium valproate
What are the side effects of sodium valproate?
Teratogenic Nausea is common - take with food Liver failure - monitor LFTs Pancreatitis Hair loss Oedema Ataxia Tremor Thrombocytopenia P450 enzyme inhibitor
What is the first line treatment for focal seizures?
Carbamazepine
Binds to sodium channels to increase refractory period
Carbamazepine may exacerbate what types of generalised seizures?
Myoclonic
Absence
What are the side effects of carbamazepine?
Dizziness Ataxia Drowsiness Visual disturbance - especially diplopia Leukopenia Mild generalised erythematous rash SIADH
P450 enzyme inducer e.g warfarin more rapidly metabolised and hormone contraception
When can lamotrigine be used?
First line instead of SV for tonic clonic, tonic or atonic
Can be used instead of carbamazepine for partial
What are the side effects of lamotrigine?
Maculopapular rash - in rare cases SJS or TEN
Visual disturbance
Tremor
Agitation
Vomiting
When can levetiracetam be used?
Second line for focal, tonic clonic and myoclonic
What are the side effects of levetiracetam?
Psychiatric side effects common - depression, agitation
D&V
Drowsiness
Why is phenytoin no longer first line?
Due to toxicity and side effect profile
Over how many months should the dose of AEDs be built up?
2 to 3 months
When switching drug what approach should be taken?
Introduce new drug slowly and only withdraw first once established on second
Epilepsy carries what percentage risk of fetal abnormalities?
5% - good seizure control prior to conception and during pregnancy is vital
What should be avoided in pregnancy?
Sodium valproate
Polytherapy
And avoid prior to conception
What is the preferred AED in pregnancy?
Lamotrigine
What advice should be given to women of child bearing age?
Take folic acid 5mg/d
What AEDs are present in breast milk?
Most except carbamazepine and valproate
Lamotrigine not thought to be harmful to infants
Which AEDs are liver enzyme inducing?
Carbamazepine
Phenytoin
Barbiturates
Enzyme inducing AEDs make which type of contraception unreliable?
Progesterone only
What is status epilepticus?
Seizure lasting more than 5 minutes or recurrent without regaining consciousness
Prolonged seizure activity can lead to what?
Irreversible brain damage
How should status epilepticus be managed?
Secure airway
Give oxygen
IV bolus lorazepam 4mg, 2nd dose if no response after 10 to 20 minutes
(Buccal midazolam if no IV access or rectal diazepam if not available)
If seizure continues start phenytoin infusion (not if bradycardia or heart block)
What percentage of cases have no identifiable cause?
70%
When does it normally present?
Childhood/teenage years
What percentage have a first degree relative with epilepsy?
30%
What can cause seizures?
Genetic component Trauma Cortical scarring e.g head injury years before Space occupying lesion Raised ICP Alcohol and benzodiazepine withdrawal Vascular abnormalities eg stroke Metabolic disturbance e.g hypoxia, low calcium, hyper/hypoglycaemia, uraemia, liver disease Infection - meningitis, encephalitis Drugs - tricyclics, cocaine
Describe a simple partial seizure
Patient remains conscious
Isolated limb jerking common
May be isolated head turning - away from side of seizure
May be isolated paraesthesia (there can be any isolated motor or sensory sign)
Weakness of the limbs may follow = Todd’s paralysis
What may indicate pseudo seizures (psychogenic non-epileptic seizures)?
Gradual onset
Prolonged duration and abrupt termination
Closed eyes +/- resistance to eye opening
Rapid breathing
Fluctuating motor activity
Episodes of motionless unresponsiveness
CNS examination normal, CT, MRI and EEG all normal
May have history of mental health problems or a personality disorder
What features indicate a frontal lobe focal seizure?
Motor symptoms- posturing, peddling movements of legs Jacksonian march Motor arrest Dysphasia or speech arrest Post ictal Todd’s palsy
What features suggest a parietal lobe focal seizure?
Sensory disturbances - tingling, numbness, pain (rare)
Motor symptoms due to spread to pre central gyrus
What features occur in an occipital local focal seizure?
Visual phenomena- spots, lines, flashes
What is a Jacksonian march?
A spreading focal motor seizure with retained awareness
Starting with face or a thumb, ipsilateral spread
What can be done as an adjunct to medication?
Psychological therapies - relaxation, CBT
When could surgical intervention be considered?
If single epileptogenic focus identified e.g in hippocampal sclerosis or small low grade tumour
Vagus nerve stimulation
Deep brain stimulation
Sudden unexpected death in epilepsy is more common in…
Uncontrolled epilepsy
May be related to nocturnal seizure associated apnoea or asystole
Oestrogen containing contraceptives lower what AED levels?
Lamotrigine - an increased dose may be required to achieve seizure control
What mnemonic can be used for cytochrome P450 inducers?
CRAPS our drugs Carbamazepine Rifampin bArbituates Phenytoin St Johns wort
What mnemonic can be used for cytochrome P450 inhibitors?
Some Certain Silly Compounds Annoyingly Inhibit Enzymes, Grrrrrr
Sodium valproate Ciprofloxacin Sulphonamide Cimetidine/omeprazole Antifungals, amiodarone Isoniazid Erythromycin Grapefruit juice
How does sodium valproate work?
Increased GABA activity - an inhibitory neurotransmitter
Inhibits sodium channels
How does carbamazepine work?
Binds to sodium channels increasing their refractory period
How does lamotrigine work?
Sodium channel blocker, thus reducing action potential propagation
How does phenytoin work?
Binds to sodium channels increasing their refractory period
What are some side effects of phenytoin?
Toxicity: nystagmus, diplopia, tremor, dysarthria, ataxia
Later: confusion, seizures
Side effects: Reduced intellect Depression Coarse facial features Gingival hyperplasia Hirsutism Peripheral neuropathy Blood dyscrasias - megaloblastic anaemia (due to altered folate metabolism) Osteomalacia - enhanced vit D metabolism Lymphadenopathy
Blood levels required for dosage (narrow therapeutic window)
When can ethosuximide be used?
Can be used instead of SV for absence seizures
What is the main excitatory neurotransmitter in the brain?
Glutamate
What receptor does glutamate act on and what affect does it have?
Acts on NMDA receptors - causes calcium influx (tells the cell to send signals)
Some with epilepsy may have fast or long lasting activation of these receptors
When can AEDs be stopped?
If seizure free for more than 2 years with AEDs being stopped over 2-3 months
What features suggest temporal lobe involvement?
HEAD
Hallucinations - auditory, olfactory, gustatory
Epigastric rising/emotional
Automatisms - lip smacking, grabbing, chewing
Deja vu/jamais vu /dysphasia
Do patients typically outgrow absence seizures?
One third of patients outgrow them, one third continue to have simple absence and one third go on to occasional concomitant generalized tonic-clonic seizures
What is another term for absence seizures?
Petit mal (old term)
What is topiramate used for?
Second line for generalised tonic clonic and myoclonic
What are the side effects of topiramate?
Nausea Drowsiness and dizziness Diarrhoea Depression Loss of appetite, weight loss Hair loss Increased ammonia leading to encephalopathy or kidney stones Blurred vision, eye pain - glaucoma
When is phenobarbitone used?
Seizures in young children
The injectable form may be used for status epilepticus
What are the side effects of phenobarbital?
Decreased level of consciousness Decreased respiratory effort Dizziness Ataxia Nystagmus
How does phenobarbital work?
Increases the activity of the inhibitory neurotransmitter GABA
Is phenobarbital a CYP450 inhibitor or inducer?
Inducer
It can be used to reduce the toxicity of some drugs
Oestrogen containing contraceptives lower… levels, so an increased dose may be needed to achieve seizure control
Lamotrigine
