Epilepsy 1

Question 0

define: epilepsy

Answer 0

a chronic disorder characterised by recurrent unprovoked seizures- more than 2 in a year

Question 1

define seizure:

Answer 1

clinical manifestation of an abnormal and excessive excitation and synchronization of a population of cortical neurones

Question 2

define epileptogenesis:

Answer 2

sequence of events that converts a normal neuronal network into a hyperexcitable network
- process by which a normal brain becomes epileptic

Question 3

where do majority of seizures predominate ?

Answer 3

in the cerebral cortex

Question 4

where can the cortical discharges of a seizure be transmitted to ?

Answer 4

muscles causing twitches or convulsions

- the seizures manifest themselves in different ways depending on the site of origin and the spread

Question 5

if the seizure is localised to the left hemisphere where will effects of the seizure be seen ?

Answer 5

it will affect the right side of the body

Question 6

what is chadwicks definition of an epileptic seizure ?

Answer 6

an intermittent, stereotyped, disturbance of consciousness, behaviour, emotion, motor function or sensation that on clinical grounds is believed to result from cortical neuronal discharge

Question 7

what can epilepsy be defined as ?

Answer 7

a condition in which seizures recur usually spontaneously

- a single episode is not considered to be epilepsy

Question 8

what type of disorder is epilepsy?

Answer 8

a heterogenous group of debilitating neurological disorders

Question 9

how many different epilepsies are there ?

Answer 9

there are about 10 types of recurrent seizures
about 40 forms of epilepsy syndromes
- this diversity reflects the numerous cellular and networks to seizure genesis

Question 10

what is the risk of recurrence of seizures after the first unprovoked seizure and the second unprovoked seizure ?

Answer 10

30-35% -first

60% -second

Question 11

what can infant suffer from but adults cant and why ?

Answer 11

benign fibrile convulsions- caused by a fever

- adults dont have them because the infant brain is more excitable so its more susceptible to these convulsions

Question 12

what is the incidence of epilepsy?

Answer 12

about 45/100000 per year

Question 13

what is the point prevalence of epilepsy ?

Answer 13

0.5-1%- it is a measure of the portion of people in a population who have a disease at a particular time

Question 14

what are the causes of epilepsy?

Answer 14

many different causes
- disturbances of the normal pattern of neuronal activity= traumatic brain injury, stroke, CNS infection, neoplasm and fever
- genetic forms- underlying genetic predisposition
-

Question 15

what can lead to epilepsy?

Answer 15

one inciting event may be sufficient or mutiple factors can lead to it

Question 16

what factors have been shown to modulate progression to epilepsy?

Answer 16

family history of seizures
age - people over 60 are more susceptible and children under 5
sex
organic brain disease- e.g tubersclerosis
psychiatric comorbidity- bipolar disorder

Question 17

in epileptogenesis what followed an initial insult?

Answer 17

followed by a clinically latent period lasting weeks to months or even years before the onset of spontaneous seizures

Question 18

what happens during the latent period ?

Answer 18

a cascade of molecular and cellular events occur that alter the excitability of the neuronal network - leading to spontaneous epileptiform activity

Question 19

how might epilepsy develop?

Answer 19

because of an abnormality in neuronal circuitry- imbalance of neurotransmitters or some combination of factors

Question 20

what is the prevalence of epilepsy ?

Answer 20

40 to 70 per thousand

about 3% of the UK pop

Question 21

what are the probabilities of having a second seizure after only seizure and what is the probability of having another seizure after having had 2?

Answer 21

1 seizure previously- less than 15% chance of another one

2 seizurespreviously - greater than 85% of another one

Question 22

what are some potential causes of epilepsy in infancy and childhood?

Answer 22

• prenatal or birth injury
• inborn error of metabolism
• congential malformation

Question 23

what are the aetiologies for epilepsy in childhood and adolescence ?

Answer 23

• idiopathic/genetic syndrome
• CNS infection
• trauma

Question 24

what are the aetiologies for epilepsy in adolescence and young adults?

Answer 24

head trauma | drug intoxication and withdrawal- alcoholics that completely stop taking alcohol can lead to seizures

Question 25

what are the aetiologies of epilepsy in older adults ?

Answer 25

stroke brain tumour neurodegeneration acute metabolic disturbances

Question 26

what is the classification of seizures based on and what are they ?

Answer 26

based on site of seizure onset in the brain - PARTIAL- initial activation of a limited number of neurones in a part of 1 hemisphere - GENERALIZED- initial activation of neurones throughout both hemispheres - SECONDARY GENERALIZED- partial seizure that later spreads to involve the majority of the 2 cerebral hemispheres

Question 27

what does an epileptic patients experience of a seizure depend on ?

Answer 27

depends on what part of the brain the epileptic activity starts and how widely it spreads from that area

Question 28

what are the effects caused by a partial seizure ?

Answer 28

SIMPLE- seizure activity while the person is still alert COMPLEX- seizure activity with a change in the awareness of surroudings hippocampus has been affected WITH SECONDARY GENERALIZATION- seizure activity begins in one area and spreads

Question 29

what are the effects caused by generalised seizures?

Answer 29

ABSENCE- staring and blinking without falling MYOCLONIC- jerking movement of the body TONIC-CLONIC- stiffening, falling, and jerking of the body TONIC- falling and jerking of the body ACONIC- falling heavily to the ground

Question 30

what are seizures like if they arise in the parietal lobe ?

Answer 30

tingling in or jerking of legs, arms and face

Question 31

what are seizures like if they originate in the occipital lobe ?

Answer 31

flashing lights or spots and vomitting

Question 32

what are seizures like if they originate in the temporal lobe ?

Answer 32

strange smell or taste altered behaviour feeling of deja vu lip smacking or chewing movements

Question 33

what are seizures like if they originate in the frontal lobe ?

Answer 33

JACKSONIAN SEIZURE- tingling feeling in hand or arm | ADVERSIVE SEIZURE- eyes or head both turn to one side

Question 34

what does the final outcome of seizures depend on ?

Answer 34

due to the excitiability changes of neurones in specific networks

Question 35

what network is affected early on in generalised seizures?

Answer 35

thalamocortical circuitry- involved early in the attack and results in synchronised firing of neurones brain wide, unconsciousness and often violent rhythmic shaking of body parts

Question 36

what are thalamocortical fibres and what do they do ?

Answer 36

specialised neurones in the thalamus with profuse connections to the entire brain -during sleep they disrupt the individual activities of cortical neurones and entrain them all into monotonous rhythmic synchronised discharges

Question 37

what are the competing hypotheses for generealised seizures ?

Answer 37

some have proposed that the primary abnormality lies in the cortex whilst others state it is in the subcortical centrencephalic system

Question 38

what are the incidences of seizure types ?

Answer 38

``` complex partial- 36% other partial- 7% generalised tonic-clonic- 23% other generalised- 8% myoclonic- 3% absence-6% simple partial- 14% ```

Question 39

how are epilepsy disorders subdivided and what are the distinctions based on ?

Answer 39

subdivided by presumed cause | distinctions are based on clinical ad EEG signs and symptoms

Question 40

what are cryptogenic epilepsies?

Answer 40

thought to arise from an unidentified brain lesion or disorder - in children it also implies a normal neurological development before the onset of the seizure disorder cryptogenic and symptomatic are the same, the only distinction is the sophistication of current diagnostic techniques

Question 41

why is epilepsy difficult to diagnose ?

Answer 41

because many other disorders such as migraines and panic attacks have similar symptoms

Question 42

what tests do neurologists normally carry out to diagnose epilepsy?

Answer 42

EEG- look for changes in the brains electrical patterns that are related to the seizures blood tests- look for certain medical disorders MRI scan- spot any defects in the structure of the brain

Question 43

what are EEGs?

Answer 43

they use scalp electrodes to record the electrical activity along the scalp produced by the firing neurones in the brain - electrodes are placed on the scalp and the electrical impulses in the vrain are amplified and summed into waves that can be monitored

Question 44

what is a hallmark of generalised epilepsy ?

Answer 44

typical 3 to 4 hz spike wave discharges over entire surface of the brain

Question 45

what is seen in patients with absence seizures ?

Answer 45

no outwardly noticeable symptoms

Question 46

how are experimental seizures induced in animal models?

Answer 46

by some noxious event | - injection of proconvulsant drug(pilocarpine induced) or electrical stimulation( kindling)

Question 47

what is the kindling model ?

Answer 47

repeated subthreshold electrical stimulation of limbic regions - usually amygdala, temporal lobe involved in anxiety response repeated stimulation lowers the threshold for more seizures to occur therefore aafter a few days only need very low intensityy to get a repsonse then eventually you get spontaneous seizures

Question 48

what initiating agents are used in adult animals to study the long term development of epilepsy ?

Answer 48

- lateral fluid percussion injury- traumatic brain injury - kainic acid status epilepticus - lithium-pilocarpine status epilepticus - intrahippocampal stimulation - amygdala stimulation - cortical stroke models

Question 49

define status epilepticus :

Answer 49

30 mins of sustained seizure activity or 2 or more seizures during this time period without full recovery - people can die from this because it can affect their respiration

Question 50

what is pilocarpine ?

Answer 50

a non-selective muscarinic receptor agonist in the PNS- used to induce chronic epilepsy in rodents

Question 51

what are the strategies to develop genetic models of epilepsy ?

Answer 51

by serendipity- epilepsy observed in a strain of animals and the seizures are characterised and validated as their clinical relevance- through inbreeding a mouse was homozygous with a mutation in a calcium gene and had epilepsy genetic engineering based on known genetic defects identified in families with epilepsy hypotheses driven experiments- a given gene is over of under expressed or deleted to test a specific hypothesis

Question 52

what is the racine scale?

Answer 52

is a seziure classification system used to define focal experimental seizures

Question 53

what was the racine scale originally developed for ?

Answer 53

to describe electrically evoked motor events and was effective because the time of seizure occurence was under the experimenters control

Question 54

what are the 5 stages of the racine scale?

Answer 54

1) mouth and facial movements 2) head nodding 3) forelimb clonus 4) rearing 5) rearing and falling