24) Epilepsy

Question 1

Define Epilepsy

Answer 1

Transient occurrence of signs and symptoms due to abnormal electrical activity in the brain leading to a seizure

Question 2

Outline the pathology of seizures

Answer 2

Caused by homeostatic loss of control due to increased excitatory activity and decreased inhibitory activity in the brain leading to a spread of neuronal hyperactivity

Question 3

What are the symptoms and signs of a patient suffering from epilepsy

Answer 3

Generalised Seizure:
> loss of consciousness often
> Changes in muscle tone
> Tongue biting

Tonic Clonic:
> Hypertonic phase followed by rapid Clonus (Shaking/Jerking)

> Often aura prior to seizure

Question 4

What factors can precipitate Epileptic Fits

Answer 4

> Photogenic
> Musicogenic 
> Thinking 
> Eating 
> Hot water immersion 
> Reading 
> Orgasm 
> Movement

Question 5

How is Epilepsy Classified ?
> Focal
> Generalised

Answer 5

Focal:
> Patient retains consciousness
> Awareness can be impaired or normal

Generalised:
> Electrical discharge spreads across both hemispheres of the brain resulting in a loss consciousness
> Types include Tonic - Clonic ; Absence ; Myoclonic ; Atonic

Question 6

What is Status Epilepticus

> Treatment

Answer 6

A seizure lasting longer than 5 minutes / Multiple seizure without a complete recovery inbetween .
> This is a medical emergency as the brain sues up all its resources and Hypoxia occurs

Treatment:
> Wait 5 minutes
> Benzodiazepines
> Benzodiazepines (Rectal / Buccal0
> Phenytoin (Levetiracetam) 
> Thiopentone (Intensive care)

Question 7

What is the initial management of Epilepsy ?

Answer 7

ABCDE

Question 8

Outline the mechanism of Action of VGSC blockers ?

> Give Examples

Answer 8

Bind to the channel during depolarisation to prolong the inactive state of the Neurone
> Once the membrane potential goes back to normal the drug detaches

Examples:
> Cabamezepine
> Phenytoin
> Lamotrigine

Question 9

Outline the features of Carbamezepine
> Use
> CYP450 inducer
> ADRs

Answer 9

Used in all partial and generalised seizures except absence

CYP450 inducer therefore with repeated use it shortens its own half life therefore need to be monitored for dosing changes

ADRs:
> Dizziness 
> Suicidal thoughts 
> Bone marrow failure 
> Has a lot of drug drug interactions lowering the effect of Phenytoin, Warfarin, CS and oral contraceptive

Question 10

Outline the features of Phenytoin
> Use
> DDIs
> ADRs

Answer 10

Mainly used in Status Epilepticus

Highly bound to plasma proteins therefore when taken with NSAIDs the plasma levels of Phenytoin increases.

ADRs:
> Gum Hyperplasia
> Arrhythmias
> Bone marrow suppression

Question 11

When might Lamotrigine be preferred over VGSC blocker drug

Answer 11

Safer in pregnancy

Question 12

Outline the mechanism of GABA enhancing drugs

> Give examples

Answer 12

Agonists of GABA receptors, binding allows influx of Cl- ions to flow through this increases threshold for action potentials by making the membrane potential more negative

Examples:
> Sodium Valporate
> Benzodiazepines

Question 13

What are the ADRs in Sodium Valporate ?

Answer 13

> Liver Failure
Pancreatitis
Ataxic Tremor
Weight Gain

Question 14

What are the ADRs in Benzodiazepines

Answer 14

> Tolerance with chronic use
Aggression
Dependence
Respiratory / Cardiovascular Depression

Question 15

How is Epilepsy Diagnosed

Answer 15

> EEG

> MRI