Epilepsy Flashcards
Aetiology of epilepsy- Genetic
can be caused by spontaneous genetic mutations:
- for early onset epilepsy- X-linked CDKL5 (cyclin dependent kinase like 5) mutations GABA (CL-)or ACH receptor genes mutation,
VNaC, VKC mutation
- 85% of Dravet syndrome (infant)- Sodium channel α1A subunit (SCN1A) gene mutations
Aetiology of epilepsy- strucutral
- Birth trauma or anoxia (low O2)
- Congenital abnormalities (during birth and development)
- Traumatic head (brain) injures
- Disease: brain tumors (60%), meningitis, brain abscess, viral infection HIV, TB
- Stroke in Elderlies - neurodegenerative
- cerebral vascular malformations - low blood perfusion in brain - ischaemic hypoxia
Aetiology of epilepsy- metabolic
- cerebral folate deficiency
- pyridoxine deficiency
- GLUT1 transporter deficiency (hypog in brain, give ketone bodies as alternative E source)
- mitochondria disorder (avoid valproate)
- biotinase deficiency
GIVE WHAT IS IN DEFICIET
Aetiology of epilepsy- immune cells
auto-immune epilepsy
Limbic epi resulting from
- Paraneoplastic syndrome (unsual sub e.g. horomones, ab, circulate in body due to cancer)
- Voltage gated potassium channel (VGKC)complex antibodies
- NMDA receptor antibodies
Aetiology and Precipitants – Drugs Lowering Seizure Threshold (bad)
- alcohol, w/d of alcohol
- substances misuse
- BZ
- bupropion - smoking cessation drug, NDSI
- antidepressants TCA, NSRI
- ABx
- antipsychotics
Status epilepticus may present as:
- Convulsive status epilepticus
- Non convulsive status epilepticus – continuous or fluctuating epileptic twilight state
- Repeated focal seizures not associated with altered awareness
Possible Triggers of Seizures
poor sleep, stress, anxiety, fever, excessive alcohol consumption,
5% of cases, flashing/flickering lights
women- hormonal cycle.
Reading- diff colours on pages
Missing doses of anti-epileptic medication
what are the possible trt for seizure?
- med
- surgery
- vagus nerve stimulation
- psychological trt CBT, relaxation therpay
Slow sodium channel blockers:
Lacosamide
Voltage gated potassium channel opener
retigabine
Low voltage CA channel blocker
Ethosuximide
in generalised absence seizures. Calcium channel blockers inhibit slow depolarisations that are required to create spike bursts.
High voltage calcium channel blockers
gabapentin & pregabalin
Synaptic vesicle protein (SV2A) modulators
Brivaracetam and levetiracetam
Fast sodium channel blockers include:
Carbamazepine, eslicarbazepine, oxcarbazepine phenytoin, and rufinamide.
why is pyridoxine useful in treating seizure
Pyridoxine is a coenzyme for glutamic acid decarboxylase (GAD), the enzyme required for GABA synthesis. Pyridoxine deficient infants lack the capacity to synthesize GABA normally and are prone to seizures.
selective non-competitive AMPA- receptor antagonist
Perampanel
NMDA /KAINET antagonist
topiramate
Broad Spectrum AED
is it important for pt to maintain on a specific brand for these med?
V NA C blockers phenytoin, lamotrigine, valproate not carbamazepine perampanel - ampa antag topiramate - nmda and kainate antag levetiracetam phenobarbital maintain on brand IS IMPORTNAT
narrow spectrun for focal seizure
for generalised absence seizure
is it important for pt to maintain on a specific brand for these med?
carbamazepine V CA C blockers: pregabalin, gabapentin GABA transaminase inhibitor: viagabatrin GABA reuptake inhibitor: tiagabine ethosuxiamide for absence NOT important
when to initiate AED?
what are the aim for medications
Start after second seizure!
Aim for monotherapy
Combination therapy should only be added on when monotherapy fails.
Cochrane review concluded what
levetiracetam suitable for focal seizures
lamotrigine and levetiracetam suitable alternatives for generalised tonic-clonic seizures particularly for women of childbearing age for whom sodium valproate may not be an appropriate treatment option
pt factors to look out for when rx AED
Be aware of patient factors, e.g. age, gender, type of seizure, concomitant medication, allergies rash or hypersensitivity weight RF LF
what are the well tolerated add-on therapy
levetiracetam, gabapentin, pregabalin
Drugs that cause weight gain
(valproic acid, gabapentin, pregabalin, carbamazepine, retigabine and perampanel),
Enzyme inducing AEDs
carbamazepine, phenobarbital, phenytoin and primidone (barbiturate class)
Treatment withdrawal process req
Patients should have been seizure free for at least 2 years, done slowly (at least 2-3 months) and reducing one agent at a time.
there are TDM established values for which two AED?
carbamazepine (some patients) and phenytoin.
