11.1 - Epilepsy and AEDs

Question 1

what are the 2 types of generalised seizures?

Answer 1

absence and tonic-clonic

Question 2

What occurs in an absence seizure?

Answer 2

staring, eyelid twitching, few muscle jerks. normal activity post attack

Question 3

What occurs in a tonic-clonic seizure?

Answer 3

2 phases:

1) Tonic phase - body rigid, patient falls to floor, incontinence
2) clonic phase - convulsions, frothing at mouth, jerking of muscles

Followed by drowsiness, confusion or coma for several hours

Question 4

What are the 2 types of partial seizures? What occurs in each of them?

Answer 4

Simple - conscious seizure

Complex - impaired consciousness, can become generalised

Question 5

Define epilepsy

Answer 5

Tendency towards recurrent seizures

Question 6

Define status epilepticus

Answer 6

Single convulsion lasting >30mins or convulsions ocurring back to back with no recovery

Question 7

How can status epilepticus cause damage?

Answer 7

Physical injury due to fall, hypoxia, SUDEP

Question 8

How can epilepsy be classified?

Answer 8

Primary - idiopathic

Secondary - known cause

Question 9

What are some underlying causes which can result in epilepsy?

Answer 9

Brain tumours, pyrexia, alcohol or drugs or withdrawal, brain tumours, hypoglycaemia, brain injury

Question 10

How would you take a history of a seizure?

Answer 10

Witness statements, pre, peri, and post seizure

Question 11

What are the 4 types of AEDs?

Answer 11

Inhibition of glutamate release, inhibition of Ca channel, Inhibtion of Na channel, enhancement of GABA(A) action

Question 12

What are the 3 types of inhibitiors of na channels?>

Answer 12

Lamotrigine, phenytoin, carbamezepine

Question 13

What is the MoA of inhibitors of Na channels?

Answer 13

Only binds to channels in inactive state, preventing channels from returning to a resting state where they could continue to depolarise neurons. Preferentially binds high frequency discharge neurons

Question 14

What are some ADRs of carbamezepine?

Answer 14

N&V, rashes, myelosuppression, dizziness, parasthesia, teratogenic

Question 15

What are some ADRs of phenytoin?

Answer 15

Gingival hyperplasia, heaches, nystagmus, dizziness, hypersensitivity rashes, teratogenic

Question 16

What are some ADRs of lamotrigine?

Answer 16

dizziness, ataxia, nausea, rashes,

Question 17

What are the DDIs of the inhibitors of Na channels?

Answer 17

Phenytoin and carbamezepine - inducers of CYP450

Lamotrigine - oral contraceptives

Question 18

What are the 2 types of enhancers of GABA action?

Answer 18

Valproate sodium, BZDs

Question 19

Why is phenytoin used in emergency treatment?

Answer 19

Zero order kinetics - quickly reaches therapeutic levels

Question 20

What is the MoA of valproate sodium?

Answer 20

Stimulates GABA synthesis and inhibits GABA inactivation

Question 21

What is the MoA of BZDs

Answer 21

Positive allosteric modulation of GABARs.

Question 22

Give an example BZD

Answer 22

lorazepam

Question 23

What are some ADRs of valproate sodium?

Answer 23

ataxia, tremor, N&V, sedation, teratogenic

Question 24

What are some ADRs of BZDs?

Answer 24

sedation, tolerance, confusion, aggresssion, resp and CNS depression, teratogenic

Question 25

How would you prescribe an AED? What rules would you folow

Answer 25

aim for monotherapy, start low and increase dose to maximise effect and minimse ADRs

Question 26

What AED would you use for primary generalised seizures?

Answer 26

Valproate sodium or lamotrogine

Question 27

What AED would you use for partial seizures?

Answer 27

Carbamezepine or lamotrigine

Question 28

What AED would you use for Status epilepticus?

Answer 28

BZD and IV phenytoin

Question 29

What AED would you use in pregnancy and why? What other supplements would you combine it with?

Answer 29

Use lamotrigine - reduced teratogenic effects
Combined with folate and vit K supplements. Vit K reduces risk of cerebral hemorrhage and coagulopathy associated with AED-linked vit K deficiency. Folate reduces risk of neural tube defects

Question 30

What would you do in an emergency involving status epilepticus?

Answer 30

1) ABC
2) lorazepam and then IV phenytoin
3) treat underlying cause
4) if all else fails, ITU referral with paralysis, sedation and intubation

Question 31

Give some secondary causes of epilepsy

Answer 31

alcohol, drugs, withdrawal, flashing lights, pyrexia, brain tumours