Cellular Basis of Epilepsy

Question 1

What defines epilepsy?

Answer 1

Having 2 or more seizures, with an ongoing predisposition to further seizures

Question 2

What is a simple partial seizure?

Answer 2

Aura - confined to limbic structures in temporal lobe

Question 3

What is the focal discognitive phase of a seizure?

Answer 3

As the seizure spreads to conscious areas, the patient becomes unaware of automatic behaviours they are producing

Question 4

What is a secondary convulsive seizure?

Answer 4

Involvement of the bilateral motor areas; horrible crying/moaning is typical, characterized by generalized limb stiffness followed by generalized limb jerking

Question 5

What is epilepsy?

Answer 5

neurological condition with enduring alterations in the brain, resulting in abnormally increased predisposition to seizures

Question 6

What can cause an acute symptomatic seizure?

Answer 6

trauma/head injury, drug intoxication, severe metabolic illness, stroke

Question 7

What are the 3 major causes of epilepsy?

Answer 7

Genetic (idiopathic/primary), structural/metabolic (symptomatic/secondary to tumour, scarring, etc.), and unknown

Question 8

How are seizures characterized?

Answer 8

Based on clinical features (representing the parts of the brain affected) and EEG findings

Question 9

What are epileptic syndromes?

Answer 9

epileptic disorders with similar signs, symptoms, prognosis, and response to treatment

Question 10

What are partial (focal) seziures?

Answer 10

starts in a geographically limited part of one hemisphere and may or may not spread to involve other parts of the brain - mostly arises from structural or metabolic abnormalities

Question 11

What are generalized seizures?

Answer 11

arise simultaneously in both hemispheres, rapidly engaged bilaterally with widely distributed networks - usually genetic

Question 12

What are the types of seizure?

Answer 12

partial (focal), generalized, and unclassifiable

Question 13

What are the types of epilepsy?

Answer 13

genetic (idiopathic), structural/metabolic (symptomatic), and unknown

Question 14

What is genetic epilepsy?

Answer 14

most common in childhood & teenage years; usually respond well to tx or remit; underlying brain is structurally and functionally normal, genetic basis such as ion channels

Question 15

What is structural/metabolic epilepsy?

Answer 15

identifiable underlying structural or functional brain abnormality; not easily tx or remitting; more common as you age

Question 16

What is a Jacksonian seizure?

Answer 16

starts in the motor cortex causing focal jerking of one hand that gradually spreads up the arm to involve the face and leg as it moves up the cortex

Question 17

Epilepsy is primarily a disease of

Answer 17

cortical grey matter

Question 18

What generates a seizure?

Answer 18

disturbance of the balance between inhibition and excitation of cortical neurons and neural networks (circuits can be small and localized or widely distributed and generalized) resulting in uncontrolled, hypersynchronous, self-sustained firing

Question 19

What type of alterations in neuronal network components contribute to the mechanism of seizure?

Answer 19

loss of inhibitory neurons (esp. hippocampus; lost first); gain of excitatory neurons forming aberrant circuits; aberrant sprouting of severed axons; alterations in intrinsic neuronal excitability (ion channels); alterations in synaptic transmission; alterations in extra-neuronal environment (glial function in NT uptake)

Question 20

What is the most sensitive brain structure to developing an epileptic network?

Answer 20

the hippocampus in the mesial temporal region

Question 21

What is the most common cause of drug-resistant temporal lobe epilepsy?

Answer 21

Hippocampal lobe sclerosis

Question 22

Epileptic remodelling in hippocampal sclerosis can include

Answer 22

cell loss (CA1), abnormal (mossy) fibre sprouting, excess proliferation of glial cells

Question 23

Onset of epilepsy in infancy/early childhood is most commonly

Answer 23

congenital/perinatal CNS insult

Question 24

Onset of epilepsy in late childhood/early adulthood is most commonly

Answer 24

idiopathic/genetic

Question 25

Onset of epilepsy in adult/elderly (60+) is most commonly

Answer 25

symptomatic/structural

Question 26

What is the basis of genetic causes of epilepsy?

Answer 26

multiple or several different polymorphisms in ion channels that result in a tendency to epileptic firing - VG and ligand-gates but also non-ion channel gated genes like structural elements