Other epilepsy questions

Question 1

What are causes of epilepsy?

Answer 1

• Gene mutations (particulary ion channel mutations)
• An initial precipitating event (eg. brain trauma) which creates hyper-excitable circuitry from structural/functional changes.
• 25% of cases due to underlying cause (brain trauma, infection, tumour growth etc.)
• 65-75% of cases idopathic

Question 2

What is epilepsy?

Answer 2

A disruption of the normal electrochemical activity of the brain that results in seizures.
- Epilepsy is only diagnosed when there is a tendency to have recurrent seizures. (Ie not everyone who has a seizure has epilepsy).

Question 3

What can provoke seizures?

Answer 3

• Sleep deprivation
• Excess alcohol
• Illict stimulant drugs
• Antihistamines and psychological stress
• Some prescription drugs (eg. pethidine, tramadol, buproprion).

Question 4

When to start treatment?

Answer 4

• when the impact of further seizures outweighs the risk of treatment.
• If 2 or more seizures within a 6-12 month period (after 1st seizure only 30-50% of patients will have a reoccurrence).
• risk of seizure recurrence is increased in those with partial (focal) seizures.

Question 5

When should therapy discontinued?

Answer 5

If patient has been 2 years seizure free withdraw from therapy.

• should be withdrawn gradually over 6 weeks for antiepileptics
• 6 months for barbiturates & benzos
• may precipitate status epilepticus if not withdrawn slowly

Question 6

Which drug has the highest teratogenic risk in pregnancy?

Answer 6

Sodium Valproate

Question 7

In women on antiepileptics unable to use the OCP, what other methods of contraception can be used?

Answer 7

• Levonorgestrel IUD
• Medroyprogesterone depot
• Copper IUD
• Condoms

Question 8

What is the mechanism of action of drugs used to treat absence seizures?

Answer 8

Drugs that act by mainly inhibiting T type Calcium channels.

• -> in absence epilepsy there is abnormal thalamocortical circuit funciton, and the thalamus has specialised T type calcium channels on specific thalamic nuclei which are implicated in the spike-wave generation.
• -> eg. ethosuximide, valproate

Question 9

What are some things to consider when selecting a drug for epilepsy treatment?

Answer 9

• Type of seizure
• Age –> benzos & phenytoin more likely to cause sedation in children.
• Future pregnancy
• Adverse effects –> eg. valproate & pregabalin can cause weight gain. PHENYTOIN has lots of SEs.
• Pharmacokinetics –> need for blood monitoring?
• Drug interactions –> eg. with contraceptives
• Time to achieve therapeutic dose –> eg. phenytoin can be started at therapeutic doses, lamotrigine & topiramate require slow introduction.
• Cost –> is it on the PBS?
• Formulations avaliable –> eg. does it come in a liquid form for those who cannot swallow?