Epilepsy and Seizures

Question 1

What is epilepsy?

Answer 1

A disorder of brain function characterised by the periodic and unpredictable occurrence of seizures.

Question 2

What is does the term “seizure” refer to?

Answer 2

The disordered, synchronous, and rhythmic firing of populations of brain neurones.

Question 3

What abnormal function is associated with epilepsy and which two types of this result in seizure activity?

Answer 3

Abnormal neurotransmitter function in the brain
Decrease in GABA-mediated inhibition
Increase in glutamate-mediated excitation

Question 4

4 different antiepileptic drugs/drug types?

Answer 4

Valproate
Phenobarbital
Benzodiazepines
Vigabatrin

Question 5

What effect does valproate have?

Answer 5

Weak effect on GABA transaminase and Na+ channels

Question 6

What effect does phenobarbital have?

Answer 6

Enhanced GABA action

Inhibition of synaptic excitation

Question 7

What effect does benzodiazepines have?

Answer 7

Enhanced GABA action

Question 8

What effect does vigabatrin have?

Answer 8

Inhibits GABA transaminase

Question 9

What are the two types of seizures?

Answer 9

Generalised - Simultaneous firing leading to engulfing of both hemispheres of the brain
Partial seizures - Also called focal seizures, can identify origin or abnormality

Question 10

What are the 4 types of generalised seizure?

Answer 10

Tonic-clonic - loss of consciousness and convulsions
Absence - loss of awareness
Myoclonic - sudden stiffening of muscles
Atonic - sudden loss of all muscle tone

Question 11

What are the 3 types of partial seizure?

Answer 11

Simple
Complex - impairment of consciousness, repeated stereotype behaviour
Secondary generalised - begins as partial, leads to full generalised

Question 12

Cause of seizure?

Answer 12

Synchronous firing of motor neurones

Question 13

Neurotransmitters involved in seizures?

Answer 13

Glutamate - excitatory

GABA - inhibitory

Question 14

GABA receptor channel type and effect when stimulated?

Answer 14

Ligand-gated Cl- ion channel - increased hyperpolarisation which inhibits generation of action potential

Question 15

Treatment goals of epilepsy treatments?

Answer 15

Reduce reuptake of GABA
Prevent conversion to SSA (reduce GABA metabolism)
Enhance receptor function (allosteric binding sites on GABA receptor can be used to modulate function i.e. increase Cl- transport for hyperpolarisation)
GABA agonist (binds to GABA receptor to induce same effect)