Epilepsy Flashcards
Epileptic seizure definition
Seizure from excessive/hypersynchronous activity of neurones in the brain
Epileptic disorder
Chronic neurological condition characterised by recurrent epileptic seizures
Symptomatic epilepsy vs idiopathic
symptomatic indicates a probable cause exists, idiopathic indicates no obvious cause so usually genetic
Simple partial seizure
Consciousness preserved, can develop into other seizure
Seizure definition
Sudden, short event with change in a person’s awareness, what they’re doing, their feelings or behaviour
Convulsion definition
Form of seizure involving excessive abnormal muscle contractions
Complex partial seizure
Unconscious seizure, can involve automatic movements and may not remember it
Often temporal lobe epilepsy
Secondary generalised seizure
Partial seizure spreads to involve both hemispheres, unconscious
Primary generalised seizure types
Tonic - sustained inc in muscle contraction
Atonic - sudden loss of muscle tone
Myoclonic- sudden involuntary muscle contraction
Tonic-Clonic- alternating tonic, clonic phases
Absence seizure- brief consciousness interruption, involves thalami-cortical circuits (petit-mal)
Status epilepticus
Prolonged/clustered seizures can develop into non-stop, requires hospital intervention to stop
Ictus on EEG
Sudden event such as seizure
Interictal spike EEG
Brief EEG spike occurring between seizure activity
Paroxysmal depolarising shift
sustained suprathreshold terminated by prolonged afterhyperpolarisation
Epileptogenesis (PDS) causes
Changes in Ca/Na/K channel activities
Inc EPSPs or dec IPSPs
Changes in synapse connectivity e.g. more than normal
Voltage + use-dependent Na channel inhibitors MOA
Phenytoin, carbamazepine, valproate, topiramate, lamotrigine block Na channels depending on use so block high-frequency discharge only
Voltage-gated Ca channel blocker MOA
Ethosuximide inhibits T-type Ca channels in thalamic neurones
Ca channel blocker use
Ethosuximide used in absence epilepsy
Valproate MOA
Inhibits GABA-transaminase which breaks down GABA, also blocks Na channels
BDZ MOA
Diazepam, clonzepam allosterically modulate GABA receptors at BDZ site to increase Cl entry
Barbiturates MOA
Phenbarbitone increases Cl flux directly and enhances GABA effect
Tiagabine MOA
Inhibits GABA uptake
Partial seizure treatment
Carbamazepine, valproate (lamotrigine in women of childbearing potential), phenytoin
Generalised tonic-clonic treatment
Valproate (lamotrigine in women of childbearing potential), carbamazepine
Generalised absence treatment
Ethosuximide
Status epilepticus treatment
Clonazepam, lorazepam
Valproate SE
Teratogenic, more so than other AEDs
Carbamazepine SE
mild neurotoxicity (dizziness, nausea, drowsiness, ataxia) Liver enzyme inducer (other drugs metabolised quicker)
Liver enzyme inducers (metabolises other drugs quicker e.g. oral contraceptives)
phenytoin, phenobarbital, carbamazepine