Epilepsy / Seizures Flashcards
What is epilepsy?
How are seizures different to convulsions?
Who does it affect?
Epilepsy is sudden synchronous electrical discharge of cerebral neurones manifesting as seizures.
Convulsions are the motor signs of electrical discharge.
Incidence of epilepsy is highest at extremes i.e. <20yrs and >60yrs
What are focal and generalised seizures?
- Focal seizures:
=> restricted to a part of cortex of one cerebral hemisphere
=> characterised by either an aura, motor features or loss of awareness. - Generalised seizures:
=> simultaneous involvement of both hemispheres
=> associated with loss of consciousness or awareness
How is epilepsy classified?
Seizures are divided by clinical pattern into 2 main groups:
Focal seizures:
i. Without impairment of consciousness
ii. With impairment of consciousness
iii. Evolving to a bilateral convulsive seizure
Generalised seizures:
i. Tonic-clonic seizures (grand mal)
ii. Absence seizures with 3Hz spike-and-wave discharge (petit mal)
iii. Myoclonic seizures
iv. Tonic, clonic and atonic seizures
What are the causes of epilepsy?
Idiopathic (2/3 of seizures)
=> Primary generalised
Structural:
i) Cortical scarring e.g. head injury years before onset
ii) Space-occupying lesion
iii) Stroke
iv) Hippocampal sclerosis e.g. after febrile convulsions
v) Vascular malformations
vi) Developmental e.g. dysembryoplastic neuroepithelial tumour ; cortical dysgenesis
Others:
i) Tuberous sclerosis
ii) Sarcoidosis
iii) Systemic lupus erythematous
iv) Polyarteritis nodosa
v) Antibodies to voltage gated potassium channel
Generalised seizure types
i) Describe a Typical Absence Seizure (petit mal).
Absence seizures begin in childhood
=> Each attack = 3Hz spike-and-wave EEG activity
=> Loss of awareness <10s
=> Patients often oblivious
=> Absence seizures are manifestation of primary generalised epilepsy, not due to tumours etc => children with absence seizures go on to develop generalised convulsive seizures
*Absence seizures can be confused with temporal lobe seizures causing transient loss of awareness
Generalised seizure types
i) Describe Generalied Tonic-Clonic Seizure (grand mal)
Prodrome phase:
=> no warning before generalised tonic-clonic seizures
=> an aura prior to a bilateral tonic-clonic seizure
Tonic-clonic phase:
=> Initial tonic stiffening followed by clinic phase of synchronous jerking limbs reducing in frequency >2mins
=> Initial cry then fall ; eyes open and tongue often bitten
Post-ictal phase:
=> Flaccid unresponsiveness followed by gradual return of awareness with confusion & drowsiness last 15mins
=> Headache common
Generalised seizure types
i) Describe Myoclonic, Tonic and Atonic Seizures.
Myoclonic seizures: jerks i.e. brief contraction of limb, face or trunk
=> common in primary generalised epilepsy
Tonic seizures: stiffening of body, not followed by jerking
Atonic seizures: sudden collapse with loss of muscle tone => falls
Focal seizure types
i) Describe focal seizures without impaired consciousness
Focal motor, sensory (olfactory, visual), autonomic or psychic symptoms => these are known as aura
No post-ictal symptoms
*Previously known as simple focal seizure
Focal seizure types
i) Describe focal seizures with impaired consciousness
Consciousness is impaired either on seizure onset or following a simple partial aura
=> commonly arises from temporal lobe
=> post-ictal feature = confusion
*Previously known as complex focal seizure
Focal seizure types
i) Describe focal seizure evolving to a bilateral convulsive seizure
In 2/3 of patients with partial seizures, the focal electrical disturbances spread widely causing a generalised seizure
=> typically convulsive
Localising features of focal seizures:
How does a temporal lobe seizure present?
Automatism - complex motor phenomena with impaired awareness varying from:
=> oral (lip smacking, chewing, swallowing)
=> manual movements (fumbling, fiddling, grabbing)
Dysphagia
Deja vu or jamais vu
Emotional disturbance i.e. sudden terror, panic, anger, or elation or derealisation (out-of-body experience)
Hallucination of smell, taste or sound
Delusional behaviour
Bizarre associations e.g. canned music at tesco’s always makes me cry and pass out
Localising features of focal seizures:
How does a frontal lobe seizure present?
Motor features i.e. posturing or peddling movements of the leg
Jacksonian march - spreading focal motor seizure with retained awareness, starting with the face / thumb
Motor arrest
Subtle behavioural disturbances
Dysphagia
Speech arrest
Localising features of focal seizures:
How does a parietal lobe seizure present?
Sensory disturbances i.e. tingling, numbness, pain
Motor symptoms => spread to pre-central gyrus
Localising features of focal seizures:
How does a occipital lobe seizure present?
Visual phenomena i.e. spots, lines, flashes
Elements of a seizure:
=> Preceding prodrome lasting hours to days with change in mood / behaviour
=> Aura implies focal seizure from temporal lobe
=> Strange feeling in the gut/deja vu or strange smell or flashing lights
=> Post-ictally: headaches, confusion, myalgia or temporary weakness after focal seizure in the temporal lobe
INFO CARD
What are primary generalised epilepsies?
Primary generalised epilepsies:
=> present in childhood & young adult life
=> 20% of all patients with epilepsies
=> Brain is structurally normal
=> Abnormalities in ion channels influencing neuronal firing, neurotransmitter release and synaptic connection
Types of primary generalised epilepsies:
=> Childhood absence epilepsy
=> Juvenile myoclonic epilepsy
=> Monogenic disorders
Describe juvenile myoclonic epilepsy.
Include:
- Clinical features
- Triggers
- Who does it affect
10% of all epilepsy patients
Starts in teenage years
Clinical features:
=> Myoclonic jerks
=> Generalised tonic-clonic seizures
=> Absence in 1/3
Triggers: sleep deprivation, alcohol, strobe lighting
Abnormal EEG
Good response to treatment
Requires life-long treatment
How do you diagnose epilepsy?
Clinical diagnosis
=> Hx from patient and witness
Good discriminators between types of blackouts:
=> Prolonged recovery period (seizures)
=> Bitten tongue (seizures)
=> Pallor (syncope) ; cyanosis (seizure)
Poor discriminators:
=> Urinary incontinence - may occur in seizures and syncope
=> Presence of injury
*All patients with a seizure must be referred for specialist assessment in <2wks
Diagnosis of seizure: taking Hx after an episode of loss of consciousness
Witness account is important:
- What happened?
=> Before: aura vs pre-syncopal prodrome
=> During: convulsion, automatism vs brief syncopal blackout and pallor
=> After: post-ictal confusion and headache vs rapid recovery in syncope
- Circumstances
=> Seizure triggers i.e. sleep deprivation, alcohol binge, drugs
=> Syncope triggers i.e. pain, heat, prolonged standing
- Epilepsy risk factors i.e. childhood febrile convulsions, head injury, meningitis, encephalitis, family Hx of epilepsy
- Previous unrecognised seizures
=> myoclonic jerks
=> absences
=> auras (focal seizures) - Alcohol excess?
- Medication lowering seizures threshold
- Driving license?
Seizures can be provoked but that would not classify as an epilepsy. ~10% of provoked seizures can reoccur because the provocation is irreversible.
What are the causes of irreversible seizures?
Trauma
Stroke / haemorrhage
Increased intracranial pressure
Alcohol or Benzodiazepines withdrawal
Metabolic disturbance (hypoxia, low calcium, disturbed sodium, uraemia, liver disease)
Infection i.e. meningitis, encephalitis
Drugs i.e. tricyclics, cocaine
Which investigations are needed in diagnosing epilepsy?
Look for provoking causes/precipitating factors
Consider EEG
Others tests:
=> MRI brain (structural lesions)
=> Drug levels - if compliant on anti-epileptic drugs
=> Lumbar puncture if infection suspected
=> Blood tests including serum calcium
=> ECG
Counselling: advise on dangers after seizure - avoid driving, swimming, heights
=> contact DVLA and avoid driving till seizure free >1yr
What is the treatment for focal partial seizures?
1st line: Carbamazepine or Lamotrigine
2nd line: Levetiracetam ; oxcarbazepine ; sodium valproate
What is the treatment for generalised tonic-clonic seizures?
1st line: Sodium valproate or Lamotrigine
2nd line: Carbamazepine ; Levetiracetam ; Topiramate
What is the treatment for absence seizures?
1st line: Sodium valproate (SE: teratogenic)
2nd line: Lamotrigine (SE: Steven Johnson’s syndrome / toxic epidermal necrolysis)
