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
