Epilepsy Flashcards
Define epilepsy
Occasional, sudden, excessive, rapid and local discharges of grey matter
Recurring tendency to seizures
What is the prevalence of epilepsy?
1% population
What is the underlying mechanism in epilepsy?
Local loss of membrane potential homeostasis starts at focal point
Relatively small number of neurones form generator site
Neurones heavily depolarise, hyperactivity spreads via synaptic transmission to other neurones
How do voltage gated Na+ channel blockers work?
Target high-frequency firing neurones, as they only get access to their binding sites during depolarisation
Once the neurone membrane potential is back to normal, the blocker detaches from the binding site
What is a partial seizure?
Focal onset
Features refer able to a part of one hemisphere
What is the difference between simple and complex partial seizures?
Complex = awareness impaired, post-Ictal symptoms
What are primary generalised seizures?
Simultaneous onset of electrical discharge throughout the cortex
No localising features
What are the different types of primary generalised seizures?
Absence Tonic-clonic Myoclonic Atonic Infantile spasms
What are absence seizures?
Brief pauses in activity, then carries on
Presents in childhood
What is aura?
Part of the seizure
Patient aware of it
May be a strange feeling in the gut, deja vu, strange smells or flashing lights
What are common post ictal symptoms?
Headache Confusion Myalgia Sore tongue Temporary weakness Dysphasia
What are the causes of epilepsy?
2/3 idiopathic
Cortical scarring, SOL, stroke
Sarcoidosis
SLE
Give some non-epileptic causes of seizure
Trauma, stroke, haemorrhage, raised ICP, alcohol / benzo withdrawal
Metabolic disturbance: hypoxia, sodium, glucose, uraemia
Liver disease
Infection
Drugs: TCAs, cocaine, tramadol
Pseudo seizures
What are the 3 key questions in diagnosing epilepsy?
Are these really seizures?
What type of seizure is it?
Any triggers?
How do you assess a first ever seizure?
Is it really their first?
Was the seizure provoked - think about non-epileptic causes
Prompt investigation
What counselling is appropriate for seizures?
Dangers of swimming, driving, heights, bathing
Employment, sports, insurance, conception
DVLA must be informed, can’t drive until seizure free for 1 year
How do you manage an acute seizure?
Seizure lasting more than 5 mins or more than 3 in 1hr Buccal midazolam or rectal diazepam IV lorazepam if IV access Protect from injury Maintain airway
What are first line treatments for tonic-clinic seizures?
Sodium valproate
Lamotrigine
What are first line for absence seizures?
Sodium valproate
Lamotrigine
What medication is first line for partial seizures?
Carbamazepine
How are epilepsy medications managed?
1 drug if possible
Slowly build up doses until seizures controlled
Changing: start 2nd until max dose reached, then withdraw old drug
How does carbamazepine work?
Voltage gated sodium channel blocker
NB also CYP inducer
What are the side effects of carbamazepine?
Leukopenia Diplopia Blurred vision Impaired balance Drowsiness
What is the mechanism of action of Lamotrigine?
Voltage gated sodium channel blocker
What are the side effects of Lamotrigine?
Maculopapular rash Diplopia Blurred vision Tremor Vomiting Agitation Aplastic anaemia
How does levetiracetam work?
Inhibits presynaptic calcium channels reducing neurotransmitter release
What are the side effects of levetiracetam?
Psych eg depression D & V Dyspepsia Drowsiness Diplopia Blurred vision
How does phenytoin work?
Voltage gated sodium channel blocker
NB CYP inducer
What are the side effects of phenytoin?
Decreased intellect
Depression
Gum hyper trophy
Polyneuropathy
How does phenytoin toxicity present?
Nystagmus Diplopia Tremor Dysarthria Ataxia
How does sodium valproate work?
Increases GABA-mediated inhibition of AP transmission by inhibiting activation of GABA and stimulating GABA synthesis
ALSO VGSC blocker
What are the side effects of sodium valproate?
Increased appetite Liver failure Pancreatitis Reversible hair loss Oedema Ataxia Teratogenic Tremor Thrombocytopenia Encephalopathy
What AED is best in women of childbearing age?
Lamotrigine
What is the risk of feral abnormality in epilepsy?
5%
What AEDs might affect the pill?
Carbamazepine
Phenytoin
What is the criteria for stopping AEDs?
Normal CNS exam
Normal IQ
Normal EEG
Seizure free for >2 yrs
What are the components of a good epilepsy review?
Seizure control Daily life DVLA First aid for carer / relatives Medications Women of childbearing age
