Epilepsy Flashcards
What is a seizure?
A seizure is the clinical manifestation of an abnormal and excessive excitation of a population of cortical neurones.
An abnormal, synchronous, paroxysmal neuronal discharge in the brain causing abnormal function.
What is epilepsy?
A tendency to spontaneous, intermittent, abnormal electrical activity in part of the brain, manifesting as seizures.
Or simply a tendency to have recurrent seizures
What is meant by an aura?
Seizures may be preceded by a sensory experience- this is an aura.
This could be a rising epigastric sensation, gustatory/olfactory hallucinations, visual changes/flashing lights, headaches, paresthesia, de ja vu
What is a symptomatic seizure?
Provoked seizures that have a cause, such as: Drugs Severe sleep deprivation CV Disease Stroke/TIA Hypoglycaemia Electrolyte imbalance Head injury (can cause scaring and seizures years after onset)
What is idiopathic epilepsy?
This is epilepsy for which a cause cannot be found (not symptomatic seizures)
What is the difference between a partial and a generalised seizure?
Partial- only affecting part of the brain within a single hemisphere
Generalised- Synchronous activity that involves both hemispheres with widespread cortical involvement
What seizure features can help to differentiate between a between a partial/focal seizure and a generalised seizure?
Focal seizures have localising features depending on the area involved
Generalised seizures do not have features that would enable them to be localised to one area of the brain, there are several distinct subtypes including absence, atonic, tonic, and tonic-clonic.
How can partial seizures be further classified?
With or without impairment of consciousness
Without Impairment of consciousness (previously called simple)- Awareness is not impaired and there are focal features. No post-ictal symptoms.
With Impairment of consciousness - awareness is impaired. Most commonly arise from the temporal lobe and post-ictal confusion is a feature.
Evolving to a bilateral convulsive seizure (used to be described as secondary generalised)- electrical disturbance initially starts focally, spreads widely and then causes a generalised seizure. Note- if it begins with focal features it is a partial seizure regardless of how quickly it generalises.
What are post-ictal features?
These are features that are present after a seizure. These may be headache, confusion, myalgia or temporary weakness (Todd’s Palsy seen after a focal seizure in motor cortex)
What proportion of epilepsy is idiopathic?
Around 2/3
What is an absence seizure? When does it typically present?
A type of generalised seizure where there is typically loss of awareness for around 10 seconds. Often presents in childhood.
Examples may be a brief pause in speech.
What is the unique feature of absence seizures on an EEG?
3Hz Spike and Wave Oscillations
What is a tonic-clonic seizure?
A type of generalised seizure where limbs stiffen (tonic phase) and then there are jerking movements (clonic phase).
Often followed by post-ictal confusion and drowsiness.
What is a myoclonic seizure?
Sudden jerking movements of a limb, face or trunk. Can cause the patient to be suddenly thrown to the ground.
They’re a type of generalised seizure
What are atonic seizures?
Sudden loss of muscle tone which can cause a fall. There is no loss of consciousness.
What is a pseudo-seizure?
Seizures that are due to a psychological problem such as severe stress, anxiety or PTSD.
Suspect if seizures have a gradual onset, prolonged duration and abrupt termination and are accompanied by closed eyes +/- resistance to eye opening, rapid breathing, fluctuating motor activity and episodes of motionless unresponsiveness. CNS exam, CT, MRI and EEG are all normal.
If a patient comes in describing seizures what kind of things would you want to ask>
Were there any witnesses who can describe what happened.
Loss of consciousness
Any potential triggers
Strange feelings beforehand (auras?)
Tongue biting
Behavioural changes- e.g. confusion, disorientated
For anyone presenting with seizures what must be done before a diagnosis of epilepsy can be made?
Must rule out provoking causes- i.e. are these symptomatic seizures that are due to a cause and are not idiopathic.
All patients with a seizure must be referred for specialist investigation and scanning within 2 weeks.
What investigations would be requested for someone presenting following complaints fo seizures?
Standard EEG- If Hx suggests that seizures are due to epilepsy. Methods may be used to trigger a seizure.
Sleep EEG- If standard EEG does not reveal an abnormal activity do a sleep EEG.
Imaging-
MRI Head- to identify structural abnormalities and is the gold standard investigation for this.
CT- If MRI not available or in the acute setting.
ECG-
To identify potential cardiac abnormalities/arthymia/ reflex anoxic seizures for example. RAS is due to a neuronal reflex that reduces HR- triggers may be something unpleasant such as pain, crying, scares…
Bloods (If appropriate)-
Electrolyte abnormalities
Calcium
Glucose
Raised WCC (Infection could be cause- meningitis, encephalitis. Note check the temperature too- febrile seizures)
CRP + ESR
Endocrine function (e.g. TFTs if suspected)
LFTS- Hepatic Encephalopathy
Renal Function- Uraemia leading to seizures?)
Drug screen- using urine.
Lumbar Puncture- If suspecting infection such as meningitis, encephalitis.
How long must a patient be seizure free till they can drive again?
At least 1 year
What are some causes of seizure?
Brain tumour Cerebral abscess Cerebral infarction Cerebral venous thrombosis AVM Drugs, Alcohol Toxins Head injury Meningitis and encephalitis Neurodegenerative disease Biochemical imbalance Febrile seizures
What is the difference between partial and generalised seizures?
Partial seizures involve only a localised part of one hemisphere
General seizures involve both hemispheres
What is secondary generalisation?
This is when partial seizures spread to involve both hemispheres of the brain becoming generalised seizures
What determines the features seen in partial onset seizures?
The area of the brain involved determines what the features will be.
What is the major excitatory neurotransmitter in the brain?
Glutamate
What is the major inhibitory neurotransmitter in the brain?
GABA
What motor symptoms may be seen in partial onset seizures?
Rhythmic twitching or jerking of one part of the body
May spread to other parts of the body/limbs leading to Jacksonian March
What sensory symptoms might be experienced in a partial onset seizure?
Tingling or numbness
Affecting as single part of the body
Flashing lights
What higher cortical symptoms might be experienced in partial onset epilepsy?
Disturbance of memory- deja vu
Confusion states
Dream like states
Fear, anger, irritability
How can partial onset seizures be subclassified?
Complex or Simple
What defines a complex partial onset seizure?
Features of a partial onset seizure with impaired consciousness
What defines a simple partial onset seizure?
Features of a partial onset seizure with no loss of consciousness
What three components do complex partial-onset seizures have?
Aura- features from simple partial onset seizure where consciousness is in tact
Automatism- Coordinated motor activity that occurred either during or after the seizure
Impaired Consciousness- Asence of motor arrest, patient may appear vacant or glazed
What are the three components of complex partial onset seizure?
Aura
Automatism/Motor Activity
Impaired consciousness
What is the most common type of partial onset seizure?
Temporal lobe epilepsy
How does temporal lobe epilepsy usually present?
Epigastric sensation that rises up to the throat
Higher cortical manifestations, deja vu, aura, altered consciousness, automatism
How does frontal lobe epilepsy usually present?
Partial onset seizures
Usually present with deviation of the head and eyes to one side
associated with jerking of the arm on the same side
May be followed by paralysis of the arm- Todd’s Paralysis
How do parietal lobe seizures usually present?
Sensory abnromalities
