13.1 epilepsy and anti epileptics

Question 1

what is a seizure?

Answer 1

a sudden irregular discharge of electrical activity in the brain, causing a physical manifestation such as sensory disturbance, unconsciousness or convolutions

Question 2

what are the classifications of seizures?

Answer 2

seizures can be

• partial
• generalised

if partial, they can be

• simple
• complex

if they are generalised they can be

• absence
• myoclonic
• tonic clonic
• tonic
• atonic

Question 3

what is the difference between partial and generalised seizures?

Answer 3

partial is focused in a single part of the brain

generalised is all over the brain

Question 4

what are the types of partial seizures?

Answer 4

partial seizures can be

• simple e.g retain consciousness
• complex e.g consciousness is impaired

generally in temporal lobe. get auras e.g auditory hallucinations and a rush of memories.

Question 5

what are the types of general seizures?

Answer 5

1) tonic clonic
1st get tonic = muscle tenses. 2nd get clonic = convulsions.

2) absence
pass out then come back and act as if nothing happened

3) status epilepticus
a medical emergency. ABCDE treatment

4) myoclonic
brief shock like muscle jerks

5) atonic
- without tone. drop attacks = can suddenly drop and carry on.

6) tonic
- stiffen up limbs.

Question 6

what anti epileptic drugs can you use and how do they work?

Answer 6

carbamazepine
lamotrigine
phenytoin
sodium valproate

cause Na channels to remain in an inactive state

Question 7

give an example of a drug that is a sodium and calcium channel blocker

Answer 7

sodium valproate

Question 8

when would you use a calcium channel blocker?

Answer 8

in the absence of seizures

Question 9

what drugs increase GABA activity?

Answer 9

benzodiazepines

barbituates

Question 10

what is levetiracetam?

Answer 10

a drug that binds to synaptic vesicles to inhibit pre synaptic calcium channel activity

therefore, inhibiting neurotransmitter release from the pre synaptic neurones

Question 11

what are some ADRs of anti epileptic drugs?

Answer 11

• dizziness
• irritability
• weight loss/anorexia
• weight gain
• insomnia
• metabolic acidosis

Question 12

how would you transition someone from one anti epileptic to another?

Answer 12

slowly withdraw old drug over about 6 weeks and overlap with new drugs

Question 13

when would you stop anti epileptic drugs?

Answer 13

consider if patient has been seizure free for at least 2 years, 60% will lively have no further seizures

but remember more disposed if

• epileptic since childhood
• on polypharmacy
• myoclonic or tonic clonic seizures
• underlying brain damage

no driving 6 months post medication withdrawal also

if going to take them off drugs do it gradually to avoid withdrawal features such as recurrent seizures and anxiety and restlessness.

Question 14

what anti epileptic drug would you give in pregnancy?

Answer 14

lamotrigine as carbamazepine and sodium valproate can use neural tube defects.

therefore try not to prescribe anything other than lamotrigine to women of childbearing age and prescribe lowest effective dose.

start folate supplements before pregnancy and if no suitable alternative is available except sodium valproate or carbamazepine, discuss contraception and specialists prenatal monitoring

ALSO if on COCP may need to increase oestrogen dose and carbamazepine is a CYP450 inducer

Question 15

how can phenytoin be tetrogenic?

Answer 15

can cause cleft lip and palate as well as heart septal defects

also has a narrow therapeutic window

Question 16

what is status epilepticus?

Answer 16

epileptic seizures occurring continuously without recovery of consciousness for 30 minutes