Epilepsy Flashcards
When was epilepsy first described?
In Babylon 1500 BCE
Was known as Miqtu (the falling sickness)
Who identified symptoms of epilepsy in 450-350 BCE?
Hippocrates
Who started a definition for epilepsy based on physiology?
Huhglings Jackson 1870
What did Hughlings Jackson identify in epilepsy?
He noticed the focal nature of it
& realised damage than area of the brain could cause epileptic seizures
Who was the first to record electrical activity on the scalp of epilepsy?
Hans Berger performed the first EEG in absence epilepsy 1931
What did Hans Berger notice in his EEG?
He noticed sudden changes in electrical rhythms in the brain
These would now be recognised as absence seizures
What did Wilder Penfield do to study epilepsy?
He used neurosurgery & brain stimulation to study epilepsy
What was a focus of Wilder Penfield’s studies & what did he discover
- He did lots of work on temporal lobe epilepsy
- He could stimulate temporal lobe & this could evoke memories in a patient (e.g. familiar memory to patient & they feel like they are apt to have an attack)
Define a seizure:
A transient occurence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain
Define epilepsy:
“A pathologic & during tendency to have recurrent seizures”
AND
“by the neuro-biologic, cognitive, psychological & social consequences of this condition”
What do all seizure types share?
Abnormal neuronal firing in a particular brain network which trigger clinical symptoms:
- May alter consciousness
- May have external signs
- Will often have an EEG signature
How do the types of seizures differ?
- Brain networks involved
- Signs & symptoms
- Causes
- Drug therapy (need to be specific to type of seizure)
- Prognosis (final outcome)
What are the 2 main types of seizures?
- Generalised seizures
- Focal seizures
What is a generalised seizure:
A seizure that starts simultaneously in both hemispheres
It spreads from there
What is a focal seizure:
Seizure starts in a focus (on one side of the brain) & then spreads across the brain
(Can spread from one hemisphere to another)
How can a focal onset seizure be classified?
- Does the patient have awareness?
- Is there motor onset or not?
- If it progresses from focal to bilateral tonic-clonic (not all will do this but it is good to classify with)
How can generalised onset seizures be classified?
Motor and non-motor symptoms
Is there tonic-clonic or other motor symptoms present
What is the definition of a generalised seizure?
“Originating at some point within, and rapidly engaging, bilaterally distributed networks”
What are the 3 types of generalised seizures?
- Typical absence
- Myoclonic
- Tonic-clonic
What is the usual onset of typical absence seizures?
Mainly childhood in onset
How long do typical absence seizures last?
Frequent brief attacks (1-30s)
(In video patient was briefly unaware w little face movements but quickly comes back around)
What happens during an typical absence seizure to the patient?
- Sudden loss & return of consciousness
- No aura (warning signs) & no post-ictal state (period after seizure where brain is recovering)
- Some involuntary movements
When an EEG is taken of an absence seizure, what does it look like?
There is a 3Hz spike and wave (electroclinical syndrome)
(Pretty sure this is seen at the start of the seizure)
What are the physical symptoms of a patient suffering a myoclonic seizure?
- Sudden, brief, shock-like muscle contractions
- Usually bilateral arm jerks (can also be legs)
What factors can affect myoclonic seizures?
- Time of day (often worse in mornings)
- Precipitated (induced) by sleep deprivation & alcohol
How can myoclonic seizure be controlled?
There are Lon-term treatments involved in this
What are the physical symptoms of a patient suffering a tonic-conic seizure?
- Sudden onset, gasp, fall
- Tonic phase w cyanosis (blush tint to skin & lips - shows circulation issues)
- Clonic phase
- Post-ictal phase
What happens in the tonic and clonic phases of a tonic-clonic seizure?
Tonic = Body becomes stiff
Clonic = Rhythmic jerking on muscles
These happen in this order (hence the name)
What is the post-ictal phase of a seizure?
Period of time after a seizure / recovery phase
Patient usually has no memory of a tonic-clonic seizure, so what can a clinician observe?
Can ask the patient about:
- Tongue bitten & incontinence
- Noisy breathing
- Headache & muscle pain afterwards
What is the generalised onset of tonic-clonic seizures?
The tonic & clonic phases appear
Some with have myoclonic involved too –> a cluster of symptoms known as generalised epilepsy –> Brain lesions not usually found as likely genetic
What is the generalised onset of atonic seizures?
Tends to occur in children w intellectual disability & bad epilepsy
What is an atonic seizure?
AKA a drop seizure
You get a little jerk then sudden total body atonia for a split second
Where do focal seizures start?
They originate in networks limited to one hemisphere –> may propagate to the other
As focal seizures propagate, what happens to the patient?
The symptoms they experience will evolve
Symptoms vary in beginning & change throughout the seizure
What is a focal with awareness seizure?
This is where the patient does not lose awareness
(Old terminology = simple partial)
What is a focal without awareness seizure?
This is where the patient loses awareness
(Old terminology = complex partial)
What is the most common type of focal epilepsy & why?
Temporal lobe seizures
Bc this is the most common area where lesions form
How common is a warning (aura) in a focal seizure?
2/3 of patients get this warning that a seizure is coming
What are the types of warnings (aura) that ppl get b4 a focal seizure?
- Epigastric rising sensation (butterflies)
- Olfactory & gustatory symptoms
- Deja vu (strong feeling of familiarity)
(May also feel fearful & autonomic symptoms)
What does it mean is a focal seizure stops after the warning (aura)?
Some seizure can stop after this as it does not spread to the other lobe
These are known as focal seizure with awareness
What happens if a focal seizure spreads to both lobes?
Loss of awareness will happen
What happens to a patient during loss of awareness in a focal seizure?
- Arrest reaction & blank stare
- Oral automatisms (lip-smacking)
- Manual automatisms
What often happens after a focal seizure (loss of awareness)?
Often experience post-ictal phase
These take a while to regain consciousness from
What are the 3 key steps in a focal seizure?
- Aura (warning phase)
- Loss of awareness
- Post-ictal phase
What are the 3 methods used to study seizures experimentally?
- Hippocampal slices exposed to stimuli, provoking acute seizures
- Animals with CNS injury causing seizures
- Rodent genetic models
How do you prepare a hippocampal slice for testing?
- Slice about 400 microns thick
- Kept alive for many hours in warm oxygenated bath
What stimuli can be applied to the prepared hippocampal slice?
- Electrical stimulus
OR
- Various convulsive stimuli (transmitter based or channel based)
Depending on which one is used - results will differ
What are the limitations of hippocampal slice to test epilepsy?
- A reduced model - not all network connections present
- Model of acute seizures only, not recurrent seizures
- Typically non-physiological triggers are needed
What are the advantages of hippocampal slice to test epilepsy?
- Realistic epileptic discharges can be created
- V detailed neurophysiology & neuropharmacology
- More humane than animals models
What are the 4 things we study from the hippocampal set up?
- Local field potentials LFPs
- Spikes
- Inter-ictal spikes
- Seizure
What is a local field potential?
An EEG but done in the brain (micro EEG)
What does a Local field potential measure?
The summed synaptic activity from thousands of neurons (it is a summary event)
Using a micro EEG
How do you measure a spike?
Impale or patch clamp an individual neurone
What does a spike show?
Shows a single neutron firing (can see spiking activity)
What is an inter-ictal spike?
A marker of epileptic activity in a cortex
Is a long event= 200ms –> indicates an area of cortex prone to seizures
What are the 3 types of stimuli used to trigger the hippocampal slice?
- Bath medium
- Drugs
- Electrical stimulation
What are the bath mediums that can be used to induce seizures in the hippocampal slice?
- Low Mg++
- Low Calcium
What are the drugs that can be used to induce seizures in the hippocampal slice?
- 4 Aminopyridine (K+ blocker)
- Bicuccilline (GABA blockers)
What is the action of the drug 4 Aminopyridine?
It blocks potassium channels that repolarise cells
A K+ blocker
What is the action of the drug Bicucculline?
It is a GABA blocker –> blocks inhibitory networks
What are the 2 things we have learned from acute slice models?
1 - Mechanisms are dependent on the model used
2 - Epileptiform discharges due to combination of effects
Finish from what have we learned in acute slice models
