Epilepsy

Question 1

Definition of epilepsy

Answer 1

Epilepsy is rather a symptom than a disease itself.

The brain loses the ability to balance between excitation and inhibition and becomes hyperexcitable in one or more areas

Question 2

Causes of epilepsy

Answer 2

mostly unknown but may result from head injury, tumors, infection, vascular disease or genetic disposition

Question 3

Old classification of seizures

Answer 3

based on observable behaviour

1) Grand mal: “Big sickness” with violent stiffening and jerking accompanied by loss of consciousness
2) Petit mal: “Little sickness” without loss of consciousness

Question 4

Modern classification of seizures

Answer 4

1) Generalised seizure: seizure involves the whole brain often with loss of consciousness
2) Partial seizure: most common type of seizures, involves a particular area (focus) but may spread from there

Question 5

Generalised seizure EEG and observable behaviour

Answer 5

EEG is characterised by simultaneously beginning high amplitude waves across large regions of the brain.
Observable behaviour in stages:
1) stiffening (tonic), sometimes breathing stops temporarily
2) sudden jerking of the body (clonic)
3) abrupt limbness (atonia)
4) regaining of consciousness

Question 6

types of partial seizures

Answer 6

1) Simple seizure: narrowly defined focal seizure with behaviour depending on the affected area
2) Secondary generalised seizure: seizure begins at focus but spreads over other large brain areas
3) Complex partial seizure: seizures often begin focused in the temporal lobes but slightly spread

Question 7

Experience of a temporal lobe seizure

Answer 7

50% of affected people experience an aura (flashing lights, zig-zag lines, blurred vision, altered consciousness)
Altered consciousness can take the form of déjà vu, jamais vu, terror, panic or ecstasy

Question 8

Absence seizures

Answer 8

can be classified as generalised or partial
people stop talking mid-stream
often displayed in children
EEG is characterised by 3 spikes

Question 9

Long-term neuropsychological issues

Answer 9

no pattern, depends on type, locus and length of seizures
correlation with cognitive impairments in children with seizures but this could be due to environmental factors or medication

Question 10

Normal brain activity vs. seizure activity

Answer 10

Normally, neurons appear to fire at random. During a seizure they all fire simultaneously
- maybe directed by a pacemaker (maybe the thalamus?)

Question 11

Drug treatment for generalised seizures

Answer 11

affecting a prolonged inhibitory effect of GABA
examples: barbiturates, benzodiazepines

the drug phenytoin changes the neuron firing frequency from high to low

Question 12

Drug treatment for absence seizures

Answer 12

GABA agonists worsen the seizures

GABA-b antagonists like zarontin are effective

Question 13

Drug treatment for partial seizures

Answer 13

same as generalised seizures:

prolong the effect of GABA or reduce the neuron firing

Question 14

Surgery treatment

Answer 14

For bad seizures that have a particular focus, this can be removed surgically
Alternatively, the corpus callosum can be cut to avoid spreading of seizures

Question 15

WADA test

Answer 15

determines whether a patient is a candidate for cutting the corpus callosum
sodium amobarbital is injected into one hemisphere to shut it down
- this reveals the functioning of memory or language

Question 16

Behavioural conditioning treatment

Answer 16

the individual patient can be conditioned to recognise a seizure onset through the aura experience to either counterbalance the sensation (e.g. smell something nice if the aura presents itself as a bad smell) or prepare for clonic behaviour (e.g. lying down, getting cushions etc.)