Epilepsy and anticonvulsants

Question 1

What is epilepsy?

Answer 1

The name for occasional, sudden, excessive, rapid and local discharges of grey matter. It is a sudden, excessive high frequency neuronal discharge.

Question 2

What is the ictal phase?

Answer 2

The actual seizure or convulsion.

Question 3

What is the interictal phase?

Answer 3

The inactive state between seizures, however some abnormal activity spikes can be recorded.

Question 4

What is epileptogenesis?

Answer 4

The underlying process that leads to the development of epilepsy.

Question 5

What is epilepsy a disorder of?

Answer 5

The cerebral cortex.

Question 6

What percentage of the population does epilepsy effect?

Answer 6

0.5-1%.

Question 7

What does drug refractory mean?

Answer 7

The condition does not respond to treatment.

Question 8

What percentage of cases of epilepsy are drug refractory?

Answer 8

30%.

Question 9

How many new cases of epilepsy are diagnosed per year?

Answer 9

30,000.

Question 10

What does it mean that epilepsy is largely idiopathic/cryptogenic?

Answer 10

The cause is unknown/it arises spontaneously.

Question 11

What percentage of cases of epilepsy are idiopathic/cryptogenic?

Answer 11

70%.

Question 12

What is one of the causes of epilepsy?

Answer 12

From birth due to structural abnormalities in the brain.

Question 13

What is a non-genetic cause of epilepsy?

Answer 13

Birth trauma such as a reduced blood supply to the brain.

Question 14

What is the one of the causes of epilepsy in the elderly?

Answer 14

Neurological/neurodegenerative processes.

Question 15

What is one of the causes of epilepsy in young adults?

Answer 15

Head trauma that may be penetrating or non-penetrating.

Question 16

What is one of the metabolic causes of epilepsy?

Answer 16

Glucose or electrolyte imbalance.

Question 17

What are some of the diseases that can cause epilepsy?

Answer 17

Meningitis, tumours or abcesses.

Question 18

What can be used to record epilepsy?

Answer 18

EEGs.

Question 19

What does EEG stand for?

Answer 19

Electro-encephalography.

Question 20

What else can be used to record epilepsy?

Answer 20

MEGs.

Question 21

What does MEG stand for?

Answer 21

Magento-encephalography.

Question 22

What do MRIs measure?

Answer 22

Structure and volume.

Question 23

What does fMRI do?

Answer 23

It relates activity to structure.

Question 24

What does PET measure?

Answer 24

It monitors local metabolism.

Question 25

What are some invasive approaches to monitor epilepsy?

Answer 25

Dural electrode arrays and implanted depth electrodes.

Question 26

Where do seizures arise?

Answer 26

Rarely in the subcortical region, mostly in the cortical region such as the frontal, parietal, occipital and temporal lobes.

Question 27

What is the most prevalent region of the brain where seizures arise?

Answer 27

The temporal lone in the cortical region - 30-40% of seizures arise here.

Question 28

What areas of the temporal lobes are involved in seizures?

Answer 28

The hippocampus, entorhinal cortex and the amygdala.

Question 29

How do temporal lobe seizures respond to treatment?

Answer 29

They do not respond to drugs but can be treated with surgical removal of parts of the lobe involved in the seizures.

Question 30

What is radical temporal lobectomy?

Answer 30

A surgery that can lower the number of seizures patients have.

Question 31

What causes seizures to arise?

Answer 31

The activity in the cortex. There is usually a dynamic balance between inhibition and excitation.

Question 32

What are the potential disturbed balances of activity in the brain?

Answer 32

More excitation with normal inhibition, decreased inhibition with normal excitation and decreased inhibition with increased excitation.

Question 33

What causes excitation and inhibition of neurons in the brain?

Answer 33

Glutamate and GABA.

Question 34

What can initiate and prolong a seizure?

Answer 34

Synaptic and intrinsic factors such as sub-threshold voltage gated Na+ channels and voltage gated Ca2+ channels.

Question 35

What causes seizures to stop?

Answer 35

K+ channel activation, Na+ channel inactivation, glutamate receptor desensitization and glutamate depletion.

Question 36

How can epilepsy be treated?

Answer 36

Blocking destabilizing currents, increasing stabilizing currents, reducing synaptic excitation (blocking glutamate receptors and release) and increasing synaptic inhibition (increasing GABA release and potentiating GABA receptors).

Question 37

What are some drugs that block voltage gated Na channels?

Answer 37

Phenytoin, carbamazepine, lamotrigine, sodium valproate.

Question 38

How do anticonvulsants work?

Answer 38

They bind to sodium channels in their inactive state.

Question 39

What drugs block voltage gated calcium channels?

Answer 39

Ethosuximide, gabapentin and phenytoin.

Question 40

How can drugs block glutamate release?

Answer 40

Block sodium and calcium channels in glutamate neurons.

Question 41

What drugs can be used to reduce glutamate vesicle fusion?

Answer 41

Levetiracetam.

Question 42

What drugs can increase GABA levels?

Answer 42

Vigabatrin and sodium valproate.

Question 43

What does GABA transaminase do?

Answer 43

It blocks GABA breakdown, increases GABA levels and increases GABA release.

Question 44

How can GABA inactivation be decreased?

Answer 44

Tigabine.

Question 45

How can GABA postsynaptic responses be increased?

Answer 45

Benzodiazepines and barbiturates.

Question 46

What is an absence seizure?

Answer 46

Epileptic activity occurs throughout the entire brain. It is a milder type of activity that causes unconsciousness without convulsions. After the seizure the person has no memory of it.

Question 47

What is a tonic-clonic seizure?

Answer 47

Electric discharges instaneously involved the entire brain. Consciousness is lost from the beginning of the seizure.

Question 48

What are the classifications of partial seizures?

Answer 48

Focal and localized.

Question 49

What is a simple partial seizure?

Answer 49

No loss of awareness.

Question 50

What is a complex partial seizure?

Answer 50

Loss of awareness.

Question 51

What is ictogenesis?

Answer 51

The process of transition from the interictal phase to the actual seizure.

Question 52

What are 5 alternative anticonvulsants?

Answer 52

Felbamate, topiramate, retigabine, levetiracetam, losigamone.

Question 53

How does felbamate act?

Answer 53

It blocks NMDA receptors.

Question 54

How does topiramate act?

Answer 54

It blocks AMPA/kainate receptors.

Question 55

How does retigabine act?

Answer 55

It activates K-currents.

Question 56

How does levetiracetam act?

Answer 56

It modifies vesicle release machinery.

Question 57

How does losigamone act?

Answer 57

It blocks low threshold Na- currents.

Question 58

What drugs are used to treat tonic-clonic seizures?

Answer 58

Phenytoin, carbamazepine, valproate, levetiracetam, vigabatrin, lamotrigine, felbamate, gabapentin.

Question 59

What are used to treat partial/focal seizures?

Answer 59

Carbamazepine, valproate, levetiracetam, sometimes phenytoin and benzodiazepines.

Question 60

What are used to treat absence seizures?

Answer 60

Ethosuximide, valproate.

Question 61

What are used to treat myoclonic seizures?

Answer 61

Benzodiazepines.

Question 62

What is used to treat status epilepticus?

Answer 62

Benzodiazepines.