Epilepsy 1 Flashcards
1
Q
what is a convulsion ?
A
when muscles contract and relax in a rapid cycle
2
Q
what is a seizure ?
A
paoxysmal events that may involve motor, sensory systems or are related to consciousness: brain involvement
can occur without epilepsy
3
Q
Epilepsy
A
a disorder where there are recurrent and often (unprovoked) seizures
4
Q
why should epilepsy not a single disorder ?
A
highly diverse spectrum of disorders that involved different symptom domains
5
Q
what are the symptom domains of Epilepsy ?
A
- muscle ridgidity
- convulsions
- ‘psychic’
- loss of consciousness
6
Q
epidemiology of epilepsy
A
- more common in children and the elderly (not common in middle age)
- many eplilepsies only seen in children
- many children ‘grow out’ of epilepsy
- rise in old age due to changes in brain structures that happen in old age e.g. strokes, dementia, tumours
1% of population have epilepsy
5% experience in their lifetime
7
Q
types of seizures
A
- myoclonic
- clonic
- tonic
- atonic
- absence
- ictal
8
Q
what is a myoclonic seizure ?
A
(myoclonus)
- involuntary twitching og muscle or muscle groups
- generally no rhytm or repeating pattern
9
Q
when can myoclonic seizures occur ?
A
- in epilepsy
- in everday life e.g. myoclonus of the diaphragm = hiccups
10
Q
what is a clonic seizure ?
A
(clonus)
- rhythmic muscle contractions
- involve large movement
11
Q
what is a tonic seizure ?
A
a phase in which there is sustained muscle contraction or tone (initial rigidity)
often seen together with clonic seizure occuring after tonic phase
12
Q
what is an atonic seizure ?
A
- involves loss of muscle tone
- ‘drop seizures’
- often loss of consciousness
13
Q
what are absence seizures ?
A
- no motor component
- brief
- short lapses in consciousness
- short recovery
sometimes people don’t notice theyve had them
14
Q
what does ictal mean ?
A
anything connected to or pertaining to a seizure (or stroke)
15
Q
how does the ILAE system classifiy seizure type ?
A
- focal onset or generalised onset or unkown onset (does it occur in a limited brain region - focal, or in both hemispheres- generalised)
Focal seizures
- aware and impaired awareness (imparement of consciousness)
- motor or non-motor onset
Generalised seizures (generally all involve a loss of consciousness) and unkown onset
- motor or non-motor (absence) onset
16
Q
what is the term for when focal onset seizures spread ?
A
focal to bilateral tonic-clonic
17
Q
what is another name for focal seizures in the old system?
A
partial seizures which are further divide into simple and complex depending on awarenesss (simple) or impaired awareness (complex)
generalised seizures used the same name
18
Q
what is another name for tonic-clonic seizures ?
A
grand mal
they are a form of generalised onset seizures
19
Q
what is another name for the absence (generlaised non-motor) seizures ?
A
petit mal
20
Q
how do they ILAE define epilepsy type ?
A
- focal
- generalised
- combined generalised and focal
- unkown
21
Q
how is epilepsy often classified ?
A
based on the age of onset
e.g. neonatal, infancy, childhood, adolescent/adult, not age related
22
Q
what is another way that is used to classify types of epilepsy not approaved by the ILAE ?
A
- using an EEG to indentify the particular brain region involved
e.g. tmeporal lobe epilepsy
23
Q
what does ADNFLE stand for ?
A
autosomal dominant nocturnal frotal lobe epilepsy
24
Q
where does the inital probelm of epilepsy stem from in the brain ?
A
an area called the focus: a group of neurones generating high frequency syncronised activity
there may be a single focus or multiple foci
25
what happens to neurons in the focus area that cause epilepsy ?
- paroxysmal depolarizing shift: neurons undergo periodic changes in resting potential (30mV)
- this results in synchronization of activity of neurons (generates high freq, activity)
- potentially remodelling of synaptic connectivity
- kindling: low levels of stimulation generates spontaneous seizures
26
what do epilepsy symptoms from the focus depend on ?
brain area(s) involved (and any spread)
## Footnote
e.g. area for motor functions = motor symptoms
27
what are some triggers for epilepsy ?
- most occur spontaneously
- frequency can be modified by external factors such as stess or sleep deprivation
- some have particular triggers: e.g. photosensitive epilepsy
## Footnote
some epilepsy trigges: reading, music, hot water
28
what are the main ways of diagnosing epilepsy ?
- EEG recording via scalp electrodes (can be combined with video recording: can correlate eeg with motor activity or changes in consciousness)
- CT/MRI scan: are there any underlying causes e.g. tumour
## Footnote
- PET scans: are regions of the brain functioning differently: more for research
29
classification of epilepsy by etiology
- genetic
- structural/metabolic
| many epilepsies have unkown origins
## Footnote
in addition of alcohol abuse, certain medications etc.
30
what are genetic epilepsies due to ?
- mutations in ion channels are receptors: 'channelopathies'
- most frequently involved: GABA-A, neuronal nAChr and voltage sensitive channel
## Footnote
may cause more epilepsies than identified by inheritance patterns
31
are all channelopathies epilepsies ?
no
32
what is autosomal domnant nocturnal frontal lobe epilepsy and what is the cause?
- seizures happen at night during sleep
- linked to mutations in neuronal nAChR alpha and beta subunits
## Footnote
frequently misdiagnosed as nightmares
33
what happens when there are mutations in nAChR channels and how does this lead to ADNFLE ?
- nAChR regulates release of other neurotransmitters in CNS, and changes in these may lead to epilepsy
- receptors change sensitivity to ACh and also desensitization altered
34
what is hyperekplexia ?
- a non-epileptic channelopathy
- 'startle syndrome'
- exaggerated startle reflex
- can lead to ridgidity and abnormal gait
- can lead to learning difficulties
35
why is hyperekplexia not classfied as an epilepsy ?
- normally don't loose consciousness
- EEG generally normal
36
what is hyperekplexia linked to ?
mutations in proteins associated with glycinergic transmission in spinal cord
- subunits, transporters, cytoskeletal proteins
37
what is Dravet syndrome ?
a severe, inherited form of epilepsy
38
why can epilepsy occur in animals ?
- in dogs it tends to be hereditary
- in cats hereditary epilepsies are unommon, and most occur for an unkown reason or another disorder e.g. cancer
39
what are the 3 main methods used in animal models of epilepsy ?
- genetic models
- chemicalled induced models
- electrically induced models
40
41
What method was traditionally used to develop genetic models for epilepsy?
Selective breeding of rats and mice
42
What is the genotype of the mouse that displays a recessive neurological disorder similar to absence seizures?
Tottering mouse genotype
43
What recent technology has advanced the development of animal models for epilepsy?
CRISPR technique (gene editing)
44
What has facilitated the development of animal models with higher aetiological validity?
Identification of many causative genes in human genetic epilepsies
45
Name a syndrome for which there are several different mouse models developed.
Dravet syndrome
46
Which gene is mutated in the models developed for Dravet syndrome?
SCN1A
47
What type of model has been developed alongside mouse models for Dravet syndrome?
Zebrafish model
48
What is the purpose of using the zebrafish model in the context of Dravet syndrome?
To screen drugs that could potentially be used to treat this disorder
49
Fill in the blank: The 'tottering' mouse genotype displays a recessive neurological disorder that has some characteristics similar to _______.
absence seizures
50
What are some examples of chemical convulsants used to induce seizures in animals?
Kainic acid, pilocarpine, penicillin, pentylentetetrazol
## Footnote
These substances are utilized for research on antiepileptic drugs.
51
What is the primary use of administering chemical convulsants in research?
To screen antiepileptic drugs (AED)
## Footnote
This method helps identify potential treatments for epilepsy.
52
what is a limitation of chemically induced animal models for epilepsy?
they do not replicate the pathology of chronic epilepsy in humans
53
Which chemoconvulsants can lead to spontaneous seizure activity in animals after initial recovery from the chemical insult ?
Kainic acid, pilocarpine
## Footnote
These substances can create models for studying long-term seizure activity.
54
What is the limitation of using chemical convulsants for epilepsy research?
They do not replicate chronic epilepsy pathology in humans
## Footnote
This affects the translatability of research findings.
55
What are the two basic methods for inducing seizures using electric shocks?
1. Acute seizures induced by whole brain electrical stimulation
2. Stereotaxic surgery to place electrodes in specific brain regions
## Footnote
The acute method models myoclonic and tonic clonic seizures, while the second method generates kindling models.
56
What type of seizures can acute seizures induced by whole brain electrical stimulation model?
Myoclonic seizures and tonic clonic seizures
## Footnote
The type of seizure depends on the stimulus intensity.
57
What is an advantage and limitation of the acute method for inducing seizures?
Fairly easy to carry out, However, it does not mimic the disease process in humans.
58
What is the second method for inducing seizures?
Using stereotaxic surgery to place electrodes in specific brain regions
## Footnote
This method is used to generate kindling models.
59
What are the advantages of kindling models in seizure research?
Replicates human disease well
## Footnote
Kindling has been very well-studied.
60
What is a disadvantage of using kindling models?
Technically challenging and time consuming
## Footnote
This makes it unsuitable for large scale drug testing.
61
3 phases of tonic-clonic (grand mal) seizures
- aura
- tonic phase
- clonic phase
62
what is the aura phase of tonic-clonic seizures ?
- alterned sensory perception and psychic symptoms e.g. deja vu or anxiety or hallucination
- warning for seizures
- form of seizure activity: type of focal seizure with maintained consciousness
63
what is the tonic phase of tonic-clonic seizures ?
patients may lose consciousness and muscle become rigid
## Footnote
may make strange sounds
64
what is the clonic phase of tonic-clonic seizures ?
- progress into convulsions
- (potential for incontinence)
- lasts several minutes
## Footnote
longer than tonic phase
65
what happens after a grand mal seizure ?
patients often sleep and wake up feeling ill and confused / may experience cogntive difficulties
66
what is the prodromal phase of clonic-tonic seizures?
- only around 20% experience this
- sensation that starts hour or days before the seizure and can serve as a warning sign
67
what are absence seizures also know as ?
## Footnote
who are they often seen in ?
petit mal
## Footnote
childlren (sometimes adults)
68
What characterizes absence seizures?
Sudden, brief lapses in consciousness with very rapid recovery
## Footnote
These seizures can happen frequently throughout the day.
69
What is a potential brief motor component of absence seizures?
Eyelids fluttering and lip-smacking
## Footnote
This motor component is usually more subtle compared to a proper motor seizure.
70
Do individuals typically remember their absence seizures?
no
## Footnote
Usually, the person will have no memory of what has happened during the seizure.
71
How can absence seizures go undiagnosed?
Parents or teachers may notice a child 'drifting off'
## Footnote
This can be the first sign that a child is experiencing absence seizures.
72
73
What percentage of all epilepsies does juvenile myoclonic epilepsy (JME) represent?
10%
74
What is the hallmark feature of juvenile myoclonic epilepsy?
Myoclonic jerks of the arms or legs
75
At what age does juvenile myoclonic epilepsy frequently begin?
Early adolescence
76
In what percentage of cases is the myoclonic component the only symptom in juvenile myoclonic epilepsy?
17%
77
What other types of seizures may accompany myoclonic jerks in juvenile myoclonic epilepsy?
* Tonic-clonic seizures
* Absence seizures
78
What are common triggers for juvenile myoclonic epilepsy?
* Sleep deprivation
* Fatigue
* Alcohol consumption
79
When does the frequency of seizures in juvenile myoclonic epilepsy often increase?
During the University exam season
## Footnote
stress
80
What is the typical outcome for individuals with juvenile myoclonic epilepsy as they reach middle age?
Usually improves + can be controlled by drugs
## Footnote
most experience into adulthood
81
Which genes are associated with the juvenile myoclonic epilepsy?
- GABAAR alpha subunit
- GABAAR delta subunit
- EFHC1: associated with calcium channels
-CACNB4: calcium channel beta subunit
82
There was a fifth gene associated with juvenile myoclonic epilepsy, but that paper has been retracted. What gene was this ?
CLN2: chloride channel
83
What are atonic seizures?
Atonic seizures are associated with a sudden loss of muscle tone and often a brief lapse in consciousness.
84
What is another name for atonic seizures?
'Dropped seizures' is another name for atonic seizures.
85
When do atonic seizures usually begin?
Atonic seizures usually begin in childhood.
## Footnote
can persist into later life
86
What is a significant risk associated with atonic seizures?
The risk of head injury is a significant concern with atonic seizures.
87
What protective measure do children with atonic seizures often use?
Children with this type of epilepsy often wear head protection.
88
what is a gelastic seizure and what is a potential cause?
- 'laughing seizure'
- hypothalamic hamartoma: benign tumour in hypothalamus
89
what is a status epilepticus ?
single epileptic seizure that lasts longer than 5 minutes or repeated seizures within 5 minutes of each other
## Footnote
potentially fatal medical emergency
90
what type of seizures can status epilepticus involve ?
generalised
91
what is the fatality rate of status epilepticus seizures ?
- 20% of people who have them die within 30 days of seizure
OR
- left with permanent disability due to damage cause by seizure activity and lack of oxygen to the brain
92
what can cause status epilepticus seizures ?
stroke, brain tumour, head injury
93
how are status epilepticus seizures treated ?
- benzodiazepines
(or other antiepileptic meds: phenytoin)
- general anaesthetics (to control)
94
what are some general anaesthetics used to help control status epilepticus seizures ?
barbiturates or propofol
95
what are examples of some benzodiazepines used to control status epilepticus ?
lorazepam, midazolam, diazepam
96
in what animal is startle syndrome (hyperekplexia) found in and what is the cause?
irish wolfhound dogs
- mutation in glycine transporter protein
97
what is ADNFLE caused by ?
mutations in alpha and beta subunits of nAChRs
98
what percentage of epilepsies have a genetic origin ?
40%
99
what is mytonia congenita and why is it not classfied as an epilepsy ?
- caused by mutation in chloride channel in skeletal muscle
- doesn't involve the brain
100
What is the term for the site of origin of an epilepsy?
focus
