Epilepsy + seizures [SYMPOSIUM] Flashcards
Provoked seizure
Provoked seizure
- Acute symptomatic seizure provoked by acute insults.
Examples of acute insults:
- Stroke
- Alcohol withdrawal
- Metabolic disturbance
Epilepsy
- Definition
Recurring, unprovoked spontaneous seizures
Causes of epilepsy [5]
Mainly idiopathic
Post-traumatic
Chronic alcohol use
Tumour
CVD
Generalised onset seizure
Seizures characterised by electrical discharges all over the brain.
Can be primary- electrical discharges start all over the brain.
Secondary- electrical discharges started locally then spread all over the brain
Partial/focal onset seizures
Seizures characterised by electrical discharge starting from a region in the cortex.
- In EEG, seizure activity is localised
The discharge can remain localised or spread to the whole brain [causes secondary generalised]
Mainly occurs in the temporal lobe [then frontal]
Primary generalised seizures
- Classificaions
Seizures associated:
- Tonic-clonic
- Absences
- Myoclonic seizure
Tonic and atonic seizure
Idiopathic generalised seizures
- Description
Onset
- Childhood/ adolescence
Cluster of seizure types
Cause:
- Possible polygenic, no identifiable structural lesion
Photosensitivity may be present
Juvenile myoclonic epilepsy [JME]
- Type
- Proportion of epilepsy
- Onset
- Characteristics
Type
- Primary generalised epilepsy
Proportion
- 3-12% of all epilepsy
Onset:
- Juvenile, lasts lifelong
Characteristics:
- Early morning myoclonic jerks
- Photosensitivity [triggered by sleep deprivation]
- Possible absences
- Generalised TC seizures [without warning]
Tonic clonic seizures
‘Grand mal’
Seizures occur WITHOUT warning
Tonic phase
- Continuous muscle spasm
- Fall
- Cyanosis
- Tongue biting
- Incontinence
Clonic phase
- Rhythmic jerking that slows and increases in amplitude
Post-ictal phase
- Coma
- Drowsiness
- Confusion
- Muscle ache
- Headache
Temporal lobe seizure aetiology
Hippocampal sclerosis
- Accounts of half of them
Tumour
Hypoxia at birth
Vascular
Post-traumatic
Temporal lobe seizure physical symptoms
Usually emotional
Hallucinations
- Taste, speech, smell
Visual distortions
Epigastric rising sensation
Pallor/flushing/ increased HR
Automatism [actions performed unconsciously]
Lip smacking, chewing
Dystonic posture
Temporal lobe seizure cognitive symptoms
Deja vu
Speech arrest [Broca’s area]
- In dominant hemisphere
Non-speech arrest implies non-dominant hemisphere affected.
Frontal lobe seizure
-Symptoms
Eye and head deviation to contralateral side
Thrashing motor activity
Automatisms
Dystonic posturing
Jacksonian march
Simple, partial seizure
- Patient aware, localised discharge
Symptoms
- Lip smacking
- Sudden muscle contractions
- Sudden head and eye movements
- Last very briefly
Indications:
- Requires monitoring if very frequent
- Could indicate space occupying lesion
Parietal lobe epilepsy symptoms
Postive sensory symptoms
- Tingling
- Pain
Distortion of body shape
Sensory Jacksonian march
Occipital lobe epilepsy symptoms
Visual hallucinations
Amaurosis at onset
- Blackout
Antiepletic drugs that exacerbate myoclonic jerks and absences
Phenytoin
Carbamazepine
Gabapentin
Pregabalin
Alcohol withdrawal seizure
Type of acute, provoked seizure
Only scanned if subdural haematoma is suspected
Characteristics of single neurones that contribute to epileptogenicity
Instability and intrinsic excitability
Action potentials
- Positive feedback mechanism is unstable
Intrinsic excitability
- Single neurones can fire without external stimulation [pacemaker]
Characteristics of neuronal networks that contribute to epileptogenicity
One neurone has the ability to initiate a chain reaction of APs in other neurones
- Divergent and convergent synapses
Physiological components of seizure
Explosion of synchronous activity by many neurones at one
- Can spread to cortex
- Due to dysregulation of inhibitory synapses
Channelopathy- Na+
- Mechanism
- Example
Point mutation in beta Na+ channel subunit
- Makes Na+ channel inactivation very slow.
- Impairs action potential repolarisation
Examples
- Generalised epilepsy with febrile seizures [fever induced in children]
Channelopathy- K+
- Mechanism
- Example
Reduction in the number of K+ channels
- Defect in KCNQ2/3 K+ channel subunit
- Defect impairs its activation = AP repolarisation impaired
Example
- Benign familial neonatal convulsions
Physiological difference
- Primary generalised
- Secondary generalised
Secondary
- Originates from focal seizure
- Starts from group of neurones as synchronised paroxysmal depolarising shift overcomes inhibition [increases EC K+ or increases glutamate]
- Causes trains of APs
- When spread to thalamus =secondary
Primary
- From the thalamus to cerebral cortex
- Neuronal pathways in thalamus to cortex are excited
Issues women face with epileptic treatment
Dysregulation of menstrual cycle
Teratogenic
Hair thinning
Weight gain
