Epilepsy Flashcards
What percentage of the population suffers from epilepsy?
0.5-1%.
What percentage of the population suffers at least one seizure in their lifetime?
At least 2%.
How many new epilepsy cases present each year?
30,000.
What percentage of epilepsy cases are refractory to drug treatment?
30%.
What percentage of epilepsy cases arent improved by surgery?
20-30%.
Hoe many epilepsy related deaths are there per year?
1000.
What percentage of epilepsy deaths are sudden death in epilepsy (SUDEP)?
50%.
What percentage of epilepsy cases go undiagnosed or untreated in developing countries?
60-90%.
What is reflex epilepsy?
Their seizures are triggered by TV, sunlight through leaves, strobe lighting, sunlight on water. 0.001% of sufferers have musicogenic seizures. Their triggers include eating, tooth brushing, certain smells, playing chess, writing, reading, or doing sums/puzzles.
What percentage of epilepsy sufferers are affected by reflex epilepsy?
7%.
Why do seizures happen?
Sub-clinical changes in patterns of network activity drive maladaptive processes in susceptible networks. At a critical point, spontaneous recurrent seizures manifest. Epileptogenesis continues through maladaptation in target networks. ‘Seizures beget seizures’ – Gaddum.
How is behaviour affected by epilepsy?
Epilepsy is also associated with changes in behaviour that vary according to the part of the brain affected and severity and can include involuntary muscle contraction and a temporary loss of consciousness.
In most cases can the cause of epilepsy be determined?
No.
How is epilepsy studied?
To study epilepsy, we make an animal model. To do this the animal is injected with a chemoconvulsant, a brain region is stimulated, and an acute preparation is used.
Models of a system are not ever exactly perfect for the system they are trying to replicate, and this should be kept in mind.
What antiepileptic drugs act at glutamatergic synapses?
Iamotrigine, phenytoin, carbamazepine, sodium valporate, gabapentin, pregbalin.
What antiepileptic drugs block sodium channels in glutamatergic synapses?
Iamotrigine, phenytoin, carbamazepine, sodium valporate.
What antiepileptic drugs block calcium channels in glutamatergic synapses?
Gabapentin, pregbalin.
What antiepileptic drugs act at GABAergic synapses?
Vigabatrin, sodium valporate, tiagabine, benzodiazepines, barbiturates.
How do the antiepileptic drugs vigabatrin and sodium valporate work in GABAergic synapses?
By blocking GABA transaminase action, preventing GABA breakdown, increasing GABA levels and GABA release.
How does the antiepileptic drug tiagabine work in GABAergic synapses?
Blocks GABA reuptake, increasing GABA concentration in the synaptic cleft.
How do benzodiazepines and barbiturates (used for epilepsy) work in GABAergic synapses?
Increase postsynaptic response by prolonging channel opening time.
The choice of anti-epileptic drug is based upon which factors?
- Seizure type.
- Epilepsy syndrome – special syndromes (West Syndrome, Dravet).
- Pharmacokinetic profile with regards to the patient.
- Interactions/other medical conditions.
- Efficacy.
- Expected adverse effects.
- Cost.
Define partial onset seizures.
This is where the electrical disturbance is limited to a specific area of one cerebral hemisphere.
What drugs are used to treat partial onset seizures?
- Carbamazepine.
- Phenytoin.
- Felbamate.
- Primidone.
- Gabapentin.
- Tiagabine.
- Lamotrigine.
- Topiramate.
- Levetiracetam.
- Valproate.
- Oxcarbazepine.
- Zonisamide.
- Phenobarbital.
Define absence seizures.
Absence seizures are a type of generalised onset seizure, meaning both sides of your brain are affected from the start. In the past absence seizures used to be called petit-mal seizures. The 2 most common types of absence seizure are typical and atypical.
What antiepileptic drugs are used to treat absence seizures?
- Ethosuximide.
- Lamotrigine.
- Levetiracetam.
- Topiramate.
- Valproate.
- Zonisamide.
Define myoclonic seizures.
Myoclonic seizures are brief shock-like jerks of a muscle or group of muscles. They occur in a variety of epilepsy syndromes that have different characteristics. During a myoclonic seizure, the person is usually awake and able to think clearly.
What entiepileptic drugs are used to treat myoclonic seizures?
- Clonazapam.
- Lamotrigine.
- Levetiracetam.
- Topiramate.
- Valproate.
- Zonisamide.
Define tonic-clonic seizures.
During a generalized tonic-clonic (formerly grand mal) seizure, electric discharges instantaneously involve the entire brain. The person loses consciousness right from the beginning of the seizure.
What antiepileptic drugs are used to treat tonic-clonic seizures?
- Carbamazepine.
- Phenytoin.
- Felbamate.
- Topiramate.
- Lamotrigine.
- Valproate.
- Levetiracetam.
- Zonisamide.
- Oxcarbazepine.
What three categories can adverse effects to anti-epileptic drugs be broken into?
- Acute dose-related – reversible,
- Idiosyncratic – uncommon, potentially serious or life threatening.
- Chronic – reversibility and seriousness vary.
What acute, dose related adverse effects may be seen with antiepileptic drugs?
• Neurologic/Psychiatric – most common. o Sedation, fatigue. o Unsteadiness, lack of coordination, dizziness. o Tremor. o Paraesthesia – tingling. o Diplopia, blurred vision (esp. carbamazepine). o Mental/motor slowing or impairment o Mood or behavioural changes. o Changes in libido or sexual function. • Gastrointestinal (nausea, heartburn). • Mild to moderate laboratory changes. o Hyponatremia (may be asymptomatic). o Increases in ALT or AST. o Leukopenia. o Thrombocytopenia. • Weight gain/appetite changes.
What idiosyncratic adverse effects may be seen with antiepileptic drugs?
• Rash, Exfoliation.
• Signs of potential Stevens-Johnson syndrome.
o Hepatic Damage.
o Early symptoms: abdominal pain, vomiting, jaundice.
o Laboratory monitoring probably not helpful in early detection.
o Patient education.
o Fever and mucus membrane involvement.
• Hematologic damage - (marrow aplasia, agranulocytosis - CBZ).
o Early symptoms: abnormal bleeding, acute onset of fever, symptoms of anemia.
o Laboratory monitoring probably not helpful in early detection.
o Patient education.
What long term adverse effects may be seen with antiepileptic drugs?
• Neurologic:
o Neuropathy.
o Cerebellar syndrome (PHT) – irreversible – phenytoin.
• Endocrine/Metabolic Effects.
o Vitamin K/D – bleeding (HDN), osteomalacia, osteoporosis.
o Folate – Anemia, teratogenesis.
o Altered connective tissue metabolism or growth.
Facial coarsening.
Hirsutism – hair growth.
Gingival hyperplasia.
Foetal abnormalities in mothers with epilepsy can be down to what factors?
- Drug effects.
- Consequences of the mothers underlying diseases.
- Consequences of maternal seizures during pregnancy.
How should epileptic women who want to become pregnant be educated?
The patient should be properly educated on the risks they are presented with. All women of child-bearing potential should receive education and carefully considered management before and during pregnancy to optimize the chances of a good outcome for both mother and child.
What should epilepsy education for pregnant mothers include?
- Most women with epilepsy have normal children.
- Risk of fetal malformations is increased.
- AED teratogenicity is related to exposure in the first trimester of pregnancy.
- Prenatal diagnosis of fetal malformations is possible.
- Seizures may be deleterious to the fetus.
- Compliance with AED treatment is important.
Before pregnancy in an epileptic mother, what should one do?
- Attempt anti-epileptic drug monotherapy with the lowest effective dose.
- Offer folate supplementation (5mg/day orally) – to prevent spina bifida etc.
During/after pregnancy in an epileptic mother, what should one do?
- Monitor AED dose requirements to maximize seizure control.
- Continue folate supplementation.
- Consider prenatal diagnosis of fetal malformations.
- Vit K (1mg at delivery).
