Epilepsy Flashcards
What is epilepsy?
A disease of the brain where there have been at least 2 unprovoked (or reflex) seizures >24 hours apart OR 1 unprovoked (or reflex) seizure alongside probability of further seizures
What may suggest a high probability of further seizures in epilepsy?
Family history
What it epilepsy NOT?
A single diagnosis (it is a symptom of many underlying causes)
What is an epileptic seizure?
A transient occurrence of signs or symptoms due to abnormal electrical activity in the brain
What types of signs or symptoms can occur in an epileptic seizure?
- Altered consciousness
- Disturbance of behaviour
- Disturbance of emotions
- Abnormal motor function
- Abnormal sensation
Is brain activity normally synchronous or non-synchronous?
Non-synchronous
How is the electrical activity of the brain altered in epilepsy?
Groups of neurons begin to fire abnormally, excessively and in a synchronised manner resulting in a wave of depolarisation known as paroxysmal depolarising shift
What is the underlying problem in neurons leading to excessive depolarisation in epilepsy?
Loss of resistance to firing soon after previous depolarisation
What is thought to be the cause of the loss of depolarisation resistance in epilepsy?
Changes in ion channels or inhibitory neurons not functioning properly
What results from the loss of resistance to depolarisation in a specific group of neurons in epilepsy?
A specific area call the seizure focus
What factors are thought to bring on epileptic seizures?
- Stress
- Alcohol
- Lack of sleep
- Flickering lights
- Others
What is meant to by seizure threshold?
The amount of stimulus needed to induce a seizure
What happens to the seizure threshold in epilepsy?
It is lowered
What is the underlying cause of most cases of epilepsy?
Idiopathic
What are some less common underlying causes of epilepsy?
- Cerebrovascular disease
- Head injury
- Cranial surgery
- CNS infections
- Neurodegenerative disease
- Autoimmune disease
- Genetic diseases
- Drugs
- Metabolic disorders
- Alcohol binge drinking or withdrawal
What cerebrovascular disease can lead to epilepsy?
- Cerebral infarction
- Cerebral haemorrhage
- Venous thrombosis
What CNS infections can result in epilepsy?
- Meningitis
- Encephalitis
What neurodegenerative disease can result in epilepsy?
- Alzheimer’s
- Multi-infarct dementia
What drugs can cause epilepsy?
- Phenothiazides
- Isoniazids
- TCA’s
- Benzodiazepines
What metabolic disorders can cause epilepsy?
- Uraemia
- Hypoglycaemia
- Hyponatraemia
- Hypernatraemia
- Hypercalcaemia
- Hypocalcaemia
What are the risk factors for epilepsy?
- Family history
- Small for gestational age
- Seizures in first month of life
- Serious brain injury or hypoxia
- Cerebral palsy
- Developmental disabilities
- Febrile seizures
How can epilepsy be classified?
- Description of seizure
- Seizure type
- Epilepsy syndrome
- Aetiology
Why is it important to classify epilepsy correctly?
Incorrect classification can lead to in appropriate treatment
What can result from inappropriate treatment of epilepsy?
Persistent seizures
How can epileptic seizures be broadly classified?
By region affected
What are the two classifications of epileptic seizures based on area affected?
- Focal seizures
- Generalised seizures
What are focal seizures?
Seizures originating in a limited part of the brain that can remain localised or spread to be more widely distributed in one hemisphere
What were focal seizures previously known as?
Partial seizures
What are the subtypes of focal seizure?
- Focal aware seizure
- Focal impaired awareness seizures
What are focal aware seizures?
Seizures only affecting a small region of the brain with retained awareness
What areas of the brain are commonly affected in focal aware seizures?
- Temporal lobe
- Hippocampus
What were focal aware seizures previously known as?
Simple partial seizures
What are focal impaired awareness seizures?
Seizures with impaired awareness usually with total unilateral hemisphere involvement
Where do focal impaired awareness seizures arise most commonly?
Medial temporal lobe
What is it called if a focal seizure progresses to become a generalised seizure?
Secondary generalised seizure
What happens in a secondary generalised seizure?
Discharge starts in one area and then spreads to both hemispheres
What is a generalised seizure?
A seizure where there is impaired consciousness and distorted electrical activity in the whole or a large part of both hemispheres
What are the 2 categories of symptom types seen in generalised seizures?
- Convulsive
- Non-convulsive
What are the different types of generalised seizures?
- Absence
- Myoclonic
- Clonic
- Tonic-clonic
- Atonic
When is epilepsy classed as unclassified?
When no adequate description of seizures is available
What happens to consciousness in simple focal seizures?
It is unaffected
What are some common symptoms of people having a simple focal seizure?
- Sudden inexplicable emotions
- Sensations of falling or moving
- Unusual sensations
- Altered special senses
- Deja vu or jamais vu
- Laboured speech
What happens to consciousness in complex focal seizures?
It is altered
How may consciousness be affected in complex focal seizures?
- Loss of consciousness
- Confusion
- Unable to respond
What do symptoms of complex focal seizures depend on?
Part of the brain that is affected
What are the symptoms of temporal lobe complex focal seizures?
- Picking up objects for no reason
- Chewing or lip-smacking
- Muttering or repeating words
- Wandering around in confusion
How long do temporal lobe complex focal seizures generally last?
2-3 minutes
What are some symptoms of frontal lobe complex focal seizures?
- Making loud crys or screams
- Making strange postures
- Making cycling or kicking movements
How long do frontal lobe complex focal seizures generally last?
15-30 seconds
What can happen in parietal and occipital complex focal seizures?
Abnormal vision or sensations
How long do parietal and occipital complex focal seizures generally last?
15-30 seconds
What often precedes a complex focal seizure?
An aura
How can a pre-seizure aura maifest?
- Deja vu or jamais vu
- Fear
- Euphoria
- Depersonalisation
- Visual disturbance
What is the period after a seizure known as?
Post-ictal period
What can often happen in the post-ictal period of a complex focal seizure?
- Confusion
- Tiredness
How do absence seizures present?
- Vacant and unresponsiveness
- Slight muscle twitching
How long do absence seizures usually last?
Up to 30 seconds
What is another name for an absence seizure?
Petit mal seizure
What happens in a myoclonic seizure?
Extremely brief (<0.1 second) muscle contraction resulting in a jerky movement of muscle or muscle groups
What happens in a clonic seizure?
Regularly repeating (every 2-3 seconds) myoclonic movements
What happens in a tonic-clonic seizure?
- Initial tonic phase with contraction of msucles
- Clonic phase of rhythmic contractions
What may accompany the initial tonic phase in tonic-clonic seizures?
- Tongue biting
- Urinary incontinence
- Absence of breathing
What happens in atonic seizures?
Loss of muscle tone causing person to fall to the ground
What blood tests can be appropriate in trying to identify causes or differentials of epilepsy?
- Glucose
- Electrolytes
- Calcium
- Renal function
- Liver function
- Urine biochemistry
When is an EEG useful in epilepsy?
- To support a diagnosis
- To help determine the type and origin of seizure
When should EEG not be used in epilepsy?
To make a diagnosis
If a standard EEG is not helpful what could be considered?
Sleep EEG
If after standard EEG and clinical assessment, diagnosis is not certain what can be used?
Long-term video or ambulatory EEG
What is neuro-imaigng useful for in epilepsy?
Identifying structural abnormalities that can cause epilepsy
What is the imaging modality of choice in epilepsy?
MRI
When is MRI particularly important in epilepsy?
- Patient has focal onset
- Seizures continue despite first-line medication
What investigation can be performed at home in epilepsy?
Handheld video recording
When is a neuropsychological assessment indicated in epilepsy?
- Person has educational or occupational difficulties
- MRI identifies abnormality in cognitively important areas of the brain
- Reported cognitive defecits
What are some important differentials for epileptic seizures?
- Syncope
- Cardiac arrhythmias
- TIA
- Migraine
- Acute encephalopathy
- Sleep disorders such as narcolepsy
- Panic attacks
- Non-epileptic seizures
When should anti-epileptic drug therapy be started?
Only once diagnosis is confirmed (except exceptional cases)
What should be taken into account when starting a patient on anti-epileptic drugs (AEDs’)?
- Risks
- Benefits
- Epilepsy syndrome
- Prognosis
- Lifestyle
Should AED’s be used in combination?
Only if monotherapy with multiple AED’s fails
If an AED monotherapy fails to control seizures or causes side-effects how should the next one be started?
Alongside the old one and then once adequate dose is reached taper off the old one
Give 4 examples of AED’s?
- Carbamazepine
- Lamotrigine
- Phenytoin
- Sodium valproate
Why should caution be taken prescribing AED’s in women of child bearing age?
They are highly teratogenic
What must you be vigilant for in patients on AED’s?
Adverse effects
How can adherence to AED therapy be optimised?
- Educate patients
- Reduce stigma associated with epilepsy
- Use simple regimes
- Develop a positive relationship with the patient and their family
When may withdrawal of AED’s be considered?
After discussion of risks and benefits and after at least 2 years seizure free
How long should withdrawal of AED’s be conducted?
2-3 months
Withdrawal of what drugs used to treat epilepsy should extra care be taken?
Benzodiazepines and barbiturates
What adjunctive therapies may be useful in epilepsy?
- Psychological interventions
- Vagus nerve stimulation
- Surgery
What are the disadvantages of psychological interventions in epilepsy?
They have not been proven to affect seizure threshold
What sort of psychological therapies can be used in epilepsy?
- Relaxation
- CBT
- Biofeedback
What can vagus nerve stimulation do in epilepsy?
Reduce seizure frequency in refractory cases not suitable for surgery
Which epilepsy patients is surgery indicated for?
Focal refractory epilepsy
What are the most common surgical procedures in epilepsy?
Anterior and medial temporal lobe resction
What % of patients with refractory focal epilepsy undergoing anterior and medial temporal lobe restction are seizure free post-op?
70%
What are the potential complications of epilepsy?
- Social stigmatisation
- Occupational issues
- Psychological problems
- Developmental problems in children
- Accidents
- Status epilepticus
