Chapter 4 - Epilepsy

Question 1

What are the two main categories of seizures?

Answer 1

Focal (partial) seizures

Generalised seizures

Question 2

What types of seizures do ‘generalised’ seizured encompass?

Answer 2

Tonic-clonic
Tonic
Atonic
Myoclonic
Absence

Question 3

When initiating anti-epileptic treatment, what method should be taken to reduce the risk of adverse effects?

Answer 3

Titration - should start of low and then titrate upwards until seizure control is met

Question 4

If an anti-epileptic needs to be stopped or switched, how best should this occur?

Answer 4

Slowly titrating down and/or if initiating new anti-epileptic drug, this should also be titrated upwards slowly until seizure control has been met.

Question 5

Which two neurotransmitters are generally most commonly associated with excess excitation/ decreased inhibition of excited neuronal activity in the brain, causing seizures to occur?

Answer 5

Glutamate - excitory neurotransmitter
GABA - inibitory neurotransmitter

In epilepsy, there is an increase in glutamate action, causing consistent action potentials to be fired amongst neurones. GABA helps to inhibit this action.

Question 6

Anti-epileptics can be broadly categorised into 3 modes of action. What are these 3 categories?

Answer 6

1) Modulation of voltage-gated ion channels (target Na+ and Ca2+ channels)
2) Enhanced activity of synaptic inhibition (increased GABA activity)
3) Inhibition of synaptic excitement (decreased glutamate activity)

Question 7

Sodium valproate can be used for the treatment of which types of seizures?

Answer 7

All types

Question 8

Carbamazepine, Phenytoin, Lamtrogine are examples of anti-epileptics which have what MOA?

Answer 8

Act on voltage gated Na+ channels, to inhibit influx of Na+ ions into the pre-synaptic neurone — preventing depolarisation and therefore glutamate being released into the synaptic cleft and causing excitation of post-synaptic neuron

Question 9

Lamotrigine and ethosuximide are examples of anti-epileptics which have what MOA?

Answer 9

Act on voltage gated Ca2+ channels, to inhibit influx of Ca2+ ions into the pre-synaptic neurone — preventing depolarisation and therefore glutamate being released into the synaptic cleft and causing excitation of post-synaptic neuron

Question 10

How do benzodiazepines work to help control seizures?

Answer 10

Helps to potentiate the effects of GABA on GABA-A receptors — this consequently leads to an influx of Cl- ions into the post-synaptic neuron, causing replorarisation and therefore inhibition of excess excitation of neurons

Question 11

Which anti epileptic medicines need to be brand specific and patients are to be maintained on that specific brand?

Answer 11

Category 1:

Phenytoin
Carbamazepine
Phenobarbital
Primidone

Question 12

Which antiepileptic is associated with the highest teratogenic risk?

Answer 12

Sodium Valproate - highest risk of major and minor congenital malformations (in particular neural tube defects) and long term development disorders

Question 13

To reduce the risk of neural tube defects in renal patients with epilepsy who want to or are pregnant, what is advised to be prescribed?

Answer 13

Folic acid 5mg

Question 14

What is first line treatment for patients newly diagnosed with focal (partial) seizures?

Answer 14

Carbamazepine or lamotrigine ( lamotrigine is preferred)

Question 15

What is first line treatment for generalised tonic-clinic seizures?

Answer 15

Sodium valproate or lamotrigine

Question 16

What is first line treatment for absence seizures?

Answer 16

Ethosuximide or sodium valproate

Question 17

GABA analogues (Gabapentin and Pregabalin) may be used for what types of seizures? What other indication can they be used for?

Answer 17

Focal seizures

May also be used for neuropathic pain

Question 18

What else is carbamazepine licensed to be used for aside from epilepsy?

Answer 18

Trigeminal neuralgia

Question 19

Which type of seizure can lamotrigine exacerbate?

Answer 19

Myoclonic

Question 20

When initiating treatment with carbamazepine, eslicarbazepine, fosphenytoin or phenytoin, ethinicity plays an important part. Why?

Answer 20

In people of Han Chinese or Thai origin risk of drug induced Stevens-Johnson syndrome if the HLA-B*1502 allele is present

SCREENING for this allele in people of this origin is crucial if no other alternative therapy is available

Question 21

What serious side effects have been commonly reported or patients/ carers should be advised to look out for with carbamazepine, lamotrigine, oxcarbazepine and phenytoin?

Answer 21

Blood disorders

Patients should be reminded to report any signs of unexplained bleeding, bruising or signs of infection such as sore throat, malaise, fever etc

Question 22

What is the optimum plasma phenytoin concentration range?

Answer 22

10-20mg/L

Question 23

What monitoring requirements are needed for sodium valproate?

Answer 23

LFTs - hepatotoxicity has occurred with valproate use, especially in children under the age of 3

If hepatic dysfunction occurs treatment with sodium valproate should be stopped

Question 24

What specific side effects have been associated with topiramate use?

Answer 24

Acute myopia with secondary angle-closure glaucoma

Question 25

Midazolam can be used for status epilepticus but can also be used for conscious sedation. Why?

Answer 25

Fast onset of action and short duration of action which makes recovery period shorter than if other benzodiazepines were used

Question 26

Pancreatitis may develop as a result of which antiepileptic use?

Answer 26

sodium valproate

Question 27

What should patients be advised to report if taking Zonisamide?

Answer 27

Prevent and recognised signs of overheating and dehydration