Epilepsy Flashcards
Definition
Epileptic fit:
– a sudden synchronous discharge of cerebral neurones causing symptoms or signs that are apparent either to the patient or an observer.
Epilepsy is the continuing tendency to have such seizures
Aetiology
Flashing lights or flickering lights may trigger (television)
15% cerebrovascular disease
6% cerebral tumours
6% alcohol-related seizures
2% post-traumatic epilepsy
Metabolic conditions:
– hyperglycaemia
– hypercalcaemia
– acute hypoxia
Epidemiology
Common
Population prevalence of 0.7-0.8%.
Approximately 440’000 people in the UK have epilepsy
Age dependant, most cases before the age of 20 or after the age of 60 (extremes of life)
Pathophysiology
Where the neurons in the brain are synchronously active, when there not supposed to be (sending electrical signals)
Each electrical signal is really just ions moving in through the protein channels
Ion flow is controlled through neurotransmitters:
– EXCITATORY NEUROTRANSMITTERS- bind to receptors and tell the cell to open up the ion channels and relay the electrical message
– INHIBITORY NEUROTRANSMITTERS- bind to receptors and tell the cell to close the ion channels to not relay the electrical message
During a seizure, clusters of neurons in the brain become temporary impaired, and start sending out an increased amount of excitatory signals over and over.
– these are thought to be paroxysmal
– this is thought to happen due to either, TOO MUCH EXCITATION or TOO LITTLE INHIBITION
Main excitatory neuron in the brain:
– glutamate (primary receptor for glutamate is NMDA)
– NMDA responds to glutamate by opening ion channels that let calcium in (positive ion that tells the cell to send signals)
—- PEOPLE WITH EPILEPSY SEEM TO HAVE FAST OR LONG-LASTING ACTIVATION OF THESE NEURONS
Main inhibitory neuron in the brain:
– GABAergic neuron (main receptor is the GABA receptors)
—- works by telling the cell to inhibit the signal by opening channels that let in negative chloride ions
—– SOME PEOPLE WITH EPILEPSY HAVE GABA RECEPTORS THAT ARE DYSFUNCTIONAL, SO THEY ARENT ABLE TO INHIBIT SIGNALS
—- this receptors and ion channels may also be caused by:
—— brain tumours, brain injury or infection
Partial (focal) seizure:
– a seizure that starts in one area of the brain (may be localised to one hemisphere or lobe)
—- simple partial seizures- without impaired awareness, patient remains conscious (Jacksonian seizure)
—- usually presents with strange sensations and jerking movements
—- complex partial seizures- with impaired awareness, loses consciousness (Temporal love seizure) (65% are caused by hippocampal sclerosis)
Generalised seizure:
– bilateral abnormal electrical activity with bilateral motor manifestations and impaired consciousness
—- absense seizures (petit mal)
—- generalised tonic-clonic seizures (grand mal)
—- myoclonic seizures
—- tonic seizures
—- akinetic seizures
– partial seizure can come first- known as a secondary generalised seizure
Clinical presentation
Simple partial seizures:
– remains conscious (Jacksonian seizure)
– Jacksonian march- jerking starts in one group of muscles and spreads to the other groups
– strange sensations and jerking
– usually knows something is about to happen
– often remembers the seizures
Complex partial seizures (Temporal lobe seizure):
– loss of consciousness, or impaired awareness and responsiveness
– may not remember exactly what happened after the seizure
Generalised:
– tonic seizures:
—- muscles become stiff and flexed
—- pt can fall often backwards
– atonic:
—- pt becomes relaxed
—- they can fall forwards
– clonic:
—- usually have convulsions (violent muscle contractions)
– tonic-clonic (most common form of generalised seizure):
—- pt’s experience a tonic phase, where muscles tense up and become rigid.
—- followed by the clonic phase, where the muscles violently contract (convulsions)
—- eyes remain open
—- may be associated with tongue biting and incontinence of urine
—- headache is common after a tonic-clonic seizure
– myoclonic seizures:
— there is isolated muscle jerking/twitching
– absence seizures (petit mal):
—- usually a disorder of childhood
—- the child caeses activity, stares and pales for a few seconds
—- children with petit Mal, usually go on to have generalised tonic-clonic seizures when they are older
Most people usually have confusion after generalised seizures
Around 30% of patients have a first-degree relative with epilepsy, although the exact mode of inheritance is unknown
STATUS EPILEPTICUS:
– if a seizure lasts for more than 5 minutes, or if there is recurrent seizures in a row without turning to normal
—- considered a medical emergency, and should be treated instantly
Investigations
3 step process to of the evaluation of someone with epilepsy:
1. confirm if the pt has epilepsy (usually seen from the destription of the attack from the eye-witness)
- determine the patients seizure type
- EEG and CT to determine the underlying cause of epilepsy
Treatment
Antiepileptic drugs:
– are indicated when there is a firm clinical diagnosis of recurrent seizures.
