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Neuropharmacology > Epilepsy 1 > Flashcards

Epilepsy 1 Flashcards

0
Q

define: epilepsy

A

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

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1
Q

define seizure:

A

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

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2
Q

define epileptogenesis:

A

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

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3
Q

where do majority of seizures predominate ?

A

in the cerebral cortex

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4
Q

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

A

muscles causing twitches or convulsions

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

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5
Q

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

A

it will affect the right side of the body

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6
Q

what is chadwicks definition of an epileptic seizure ?

A

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

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7
Q

what can epilepsy be defined as ?

A

a condition in which seizures recur usually spontaneously

- a single episode is not considered to be epilepsy

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8
Q

what type of disorder is epilepsy?

A

a heterogenous group of debilitating neurological disorders

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9
Q

how many different epilepsies are there ?

A

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

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10
Q

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

A

30-35% -first

60% -second

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11
Q

what can infant suffer from but adults cant and why ?

A

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

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12
Q

what is the incidence of epilepsy?

A

about 45/100000 per year

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13
Q

what is the point prevalence of epilepsy ?

A

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

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14
Q

what are the causes of epilepsy?

A

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
-

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15
Q

what can lead to epilepsy?

A

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

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16
Q

what factors have been shown to modulate progression to epilepsy?

A

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

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17
Q

in epileptogenesis what followed an initial insult?

A

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

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18
Q

what happens during the latent period ?

A

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

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19
Q

how might epilepsy develop?

A

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

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20
Q

what is the prevalence of epilepsy ?

A

40 to 70 per thousand

about 3% of the UK pop

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21
Q

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?

A

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

2 seizurespreviously - greater than 85% of another one

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22
Q

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

A
  • prenatal or birth injury
  • inborn error of metabolism
  • congential malformation
23
Q

what are the aetiologies for epilepsy in childhood and adolescence ?

A
  • idiopathic/genetic syndrome
  • CNS infection
  • trauma
24
Q

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

A

head trauma

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

25
Q

what are the aetiologies of epilepsy in older adults ?

A

stroke
brain tumour
neurodegeneration
acute metabolic disturbances

26
Q

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

A

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
27
Q

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

A

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

28
Q

what are the effects caused by a partial seizure ?

A

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

29
Q

what are the effects caused by generalised seizures?

A

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

30
Q

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

A

tingling in or jerking of legs, arms and face

31
Q

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

A

flashing lights or spots and vomitting

32
Q

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

A

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

33
Q

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

A

JACKSONIAN SEIZURE- tingling feeling in hand or arm

ADVERSIVE SEIZURE- eyes or head both turn to one side

34
Q

what does the final outcome of seizures depend on ?

A

due to the excitiability changes of neurones in specific networks

35
Q

what network is affected early on in generalised seizures?

A

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

36
Q

what are thalamocortical fibres and what do they do ?

A

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

37
Q

what are the competing hypotheses for generealised seizures ?

A

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

38
Q

what are the incidences of seizure types ?

A 
complex partial- 36%
other partial- 7%
generalised tonic-clonic- 23%
other generalised- 8%
myoclonic- 3%
absence-6%
simple partial- 14%
39
Q

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

A

subdivided by presumed cause

distinctions are based on clinical ad EEG signs and symptoms

40
Q

what are cryptogenic epilepsies?

A

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

41
Q

why is epilepsy difficult to diagnose ?

A

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

42
Q

what tests do neurologists normally carry out to diagnose epilepsy?

A

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

43
Q

what are EEGs?

A

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

44
Q

what is a hallmark of generalised epilepsy ?

A

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

45
Q

what is seen in patients with absence seizures ?

A

no outwardly noticeable symptoms

46
Q

how are experimental seizures induced in animal models?

A

by some noxious event

- injection of proconvulsant drug(pilocarpine induced) or electrical stimulation( kindling)

47
Q

what is the kindling model ?

A

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

48
Q

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

A
  • lateral fluid percussion injury- traumatic brain injury
  • kainic acid status epilepticus
  • lithium-pilocarpine status epilepticus
  • intrahippocampal stimulation
  • amygdala stimulation
  • cortical stroke models
49
Q

define status epilepticus :

A

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

50
Q

what is pilocarpine ?

A

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

51
Q

what are the strategies to develop genetic models of epilepsy ?

A

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

52
Q

what is the racine scale?

A

is a seziure classification system used to define focal experimental seizures

53
Q

what was the racine scale originally developed for ?

A

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

54
Q

what are the 5 stages of the racine scale?

A

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

Neuropharmacology (15 decks)

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