TLOC, Epilepsy and EEG Flashcards
Seizure definition?
the clinical manifestation during abnormal excessive excitation and synchronisation of a population of cortical neurons
Epilepsy definition?
a tendency to recurrent seizures >24hrs apart which are not provoked by systemic or acute neurologic insults
Describe what an EEG is
records cortical electrical activity, usually from the scalp, most important neurophysiological study for diagnosis, prognosis and treatment of epilepsy, electrodes are attached in in the 10/20 system
Which side of EEG is odd numbers and which even?
Left - Odd
Right - Even
Describe the 1981 classification of seizures
Partial: Simple, complex and secondary generalised
Generalised: absence, myoclonic, atonia, tonic, tonic-clonic
Describe absence seizures
- Brief staring spells with impaired awareness
- Hypoventilation is a provoking method
- 3-20 seconds
- Sudden onset and sudden resolution,
- Typically in children, normal development and intelligence
- Typically resolved by 18 years
- Generalised 3 Hz spike waves discharge
Describe myoclonic seizures
- Brief shock-like jerk of muscles or group of muscles,
- Not all myoclonus is epileptic e.g. when falling asleep
- 4-6Hz polycyclic waves (more than one spike)
- Can be subtle or dramatic
Describe tonic seizures
- Symmetric tonic muscle contraction of extremities with tonic flexion of waist and neck
- Distinct to tonic-clonic,
- 2-20 seconds
- EEG – slow wave, attenuation (stopping) and then rapid waves
Describe atonic seizures
- Sudden loss of muscle tone,
- Floppy and fall on floor,
- Milder version just head,
- Similar EEG to tonic seizures
Describe tonic-clonic seizures
- Association with loss of consciousness and post ictal confusion/lethargy,
- Stiffening of all muscles (also larynx so can scream), followed by fast low amplitude jerking and then slow high amplitude jerking
- 30-120 seconds
- Afterwards patients very confused and not aware of where they are
- EEG- sharp activity everywhere, a lot of muscle interference
Describe a focal without impaired awareness seizure
- Aura
- Patient is aware
- Diverse range as due to where in the brain the seizure is, if in the visual cortex you can get visual aura often large coloured circles, motor = jerking, can be more subtle e.g. temporal = dream like experience
- The aura will always be the same for the patient
Desribe a focal with impaired awareness seizure
- Arise from one part of brain but patient loses awareness,
- Manifestations depend on the area affected
- Autonomisms – semi-purposeful movements
Describe a focal evolving to bilarteral tonic-clonic seizure
- Start in one place e.g. aura etc. and then spread to the whole brain
- Generalised tonic-clonic phase looks the same as primary tonic-clonic phase
- Typically 1-3 mins
- Can have Todd’s paresis – weakness on the opposite side of brain to where the seizure started
What sort of factors can be used to group epilepsy patients into syndromes
- Seizure type
- Age of onset
- Natural history/prognosis
- EEG patterns
- Aetiology/genetics
- Response to treatment
Describe temporal lobe epilepsy syndrome
- Onset at any age
- EEG shows temporal lobe epileptiform discharges
- Simple partial, complex partial and secondary generalised tonic clonic seizures can all be had
- May be symptomatic or cryptogenic
- Inter-ictal EEG shows sharp and slow waves that are abnormal
- 2 sharp waves pointing to each other – point to focus
- Can be due to hippocampal sclerosis
Describe juvenile myoclonic epilepsy syndrome
- Juvenile onset
- Myoclonic seizures, GTCS, and absences
- Seizures have morning predominance, exacerbated by sleep deprivation and alcohol
- Idiopathic
- EEG shows generalised spike or polyspike/wave discharges
- Often photosensitive (30-40%)
Describe West epilepsy syndrome
- Paediatric syndrome
- Can be symptomatic or cryptogenic
- Infantile onset
- Spasms
- Hypsarrythmic EEG – sharp waves and slow waves everywhere which are chaotic, followed by attenuation of EEG (flexion of the body and extension of limbs)
What did the 2010 classicifcation of epilepsy seizures introduce?
Introduces idea of networks:
Focalised – started somewhere in the brain which triggered one localised hemisphere network
Generalised – starts somewhere but rapidly involves bilateral network in both hemispheres
What is the criteria for mild TBI?
- Loss of consciousness <30 min
- No skull fracture
- PTA (Post trauma amnesia) <1 day
What is the criteria for moderate TBI?
- LOC >30mins and <24 hours
- With or without skull fracture
- PTA >1 <7 days
What are the criteria for severe TBI?
- LOC > 24 hours
- With contusion, hematoma, or skull
- PTA > 7 days
What is the classification for immediate seizures following TBI
within 24 hrs
What is the classification for early seziures following a TBI?
seizure within a week, skull fractures or intracranial bleed increases chance of early seizures, early seizures are an indicator for PTE
What is the classification for late seizures following TBI?
afer a week post trauma, diagnosis for PTE
What is a concussive seizure? is it epilepsy?
immediately at the trauma, thought to have different causes the tonic-clonic, looks the same but it doesn’t have same post-ictal confusion, doesn’t have an effect on likelihood to have further seizures and is not epilepsy
What is the increase in risk of getting epilepsy post TBI? What about post penetrating injury?
- The increase in risk of getting PTE is small for mild and moderate TBI
- It is larger for the severe TBI (10% increase in 5 years)
- Prevalence of epilepsy >50% after penetrating injury
What is an example of PTE latency?
• Gage – 1843 accident, 1860 first seizure, shows latent period
How does the chance of getting PTE change over time?
• There is often a latent period where no seizures are had, chance of getting PTE is still slowly increasing even 30 years post TBI
What are the 3 stages of processing neuronal repair post TBI?
3 stages post damage:
• Ion channel activation, immediate early gene activation
• Neuronal death, neuroinflammation and oxidative stress
• Neuronal loss and neurogenesis, network reorganisation, hippocampal sclerosis
Which stage is thought to be key for epilepogenesis?
network reorganisation
Was it found that treatment of early seizures post TBI were sucessful for preventing PTE?
Treatment of early seizures – reduce oxidative stress and excitotoxity, to decrease chances of getting PTE. This looks to work at the immediate point but long term no difference between phenytoin treated early seizures and placebo
Which inflammatory mediator is thought to be indicated in epileptogenesis?
IL1B
What do studies into IL1B show regarding epilepogenesis?
- Studies into the role of inflammation in PTE
- Thought that some of the inflammatory mediators contribute to epileptogenesis
- Higher levels of IL1B in CSF of patients with severe TBI than mild, this is kept raised in patients that develop epilepsy
What are the findings of studies modelling TBI in mice regarding electrophysiological biomarkers?
- Found somato - motor recovery but they develop epilepsy later on
- Another study looks at electrophysiological markers for epileptogenicity – found markers in rats EEG, but not in human until 2 years (when epilepsy symptoms already), no early marker.
What is the effect of cooling post TBI in mice?
lower number of seizures (thought to be because cooling is anti-inflammatory)
Which pathway is thought to be implicated in epileptogenesis?
mTOR
What are some of the roles of the mTOR pathway?
- mTor pathway controls cell growth and survival, proliferation and cellular metabolism, synaptic plasticity and neuronal morphology.
- Neuronal mTOR promotes axonal regeneration in response to CNS injury
What is tuberous sclerosis? Symptoms? What is it caused by?
• Tuberous sclerosis – a neurocutaneous syndrome
o Cutaneous features
o Brain abnormalities (cortical tubers, subependymal giant cell astocytomas) and epilepsy
o Caused by mutations in TSC1 and TSC2 (in the middle of the mTOR pathway)
What are the symptoms of PMSE syndromes? What is it?
An mTORopathy
o Polyhydramnios
o Megaencephaly
o Symptomatic epilepsy
What is hemi-megaencephaly? What is it caused by?
o Unilateral hemispheric enlargement associated with severe seizures
o Somatic mutations found in genes involved in mTOR pathway, such as PIK3CA, AKT3
What is focal cortical dysplasia? What is it caused by?
o Common cause of epilepsy,
o Cortical neuron migration not effective
o Somatic mutations have been found in some mTOR pathway genes
o Rare familial cases with germline mutations implicated
What is evidence that mTOR pathway is involved in the development of PTE?
- Its rapidly phosphorylated post brain injury
* Inhibition by rapamycin leads to prevention of development of PTE in mice
What is TLOC?
spontaneous loss of consciousness with complete recovery
What are possible causes of TLOC?
Cardiac Stroke or TIA Seizure disorder Vasogvagal Orthostatic hypotension Medication
Not necessarily epileptic, more cases of cardiac syncope
What are the clinical challenges of TLOC?
- Main witness unconscious – relying collateral history
- Eyewitness account unreliable but essential
- Unpredictable
- Occasionally life threatening
- Driving restrictions, health and safety
- Initial diagnosis often inaccurate, delay – person should be seen 4 weeks after first blackout
What is the major risk associated wiht TLOC?
- Can be first symptom of a fatal arrhythmia
* Sudden death is often attributed to cardiac arrhythmias
How mny people die of cardiac arrhythmias in US per annum?
350,000
What things to ask about happened before a TLOC attack ?
- Warning – aura, pre-syncopal
- Provoking features
- Associated symptoms
- Which circumstances?
- Can the attacks be prevented?
What to ask about happened during a TLOC attack (if someone witnessed it)
- Actual LOC
- Duration
- Change in complexion
- Verbal/tactile responsiveness
- Movement/limb jerking
- Injuries
- Pulse
- (tongue biting and urine incontinence – not good indicators)