Summary
Definitions
Seizure – spontaneous uncontrolled abnormal brain activity
Epilepsy – a tendency to have seizures. Epilepsy is a symptom, and not a true condition. Epilepsy can be diagnosed after a minimum of 2 seizures.
Ictus – can refer to any acute event, in this situation, refers to the epilepsy attack itself.
Prodrome - a set of not specific symptoms that precede the onset of a disease, in this case, epilepsy
Aura – sensory disturbances that precede an attack, usually just by a few minutes. Can be visual, tactile, olfactory – pretty much any sensation.
Epidemiology
- The lifetime risk of having a seizures is about 1-2%
- Prevalence of epilepsy is about 0.5% - i.e. it is very common!
- 70% of cases have no identified cause
- 70% of cases are well controlled with drug treatment
- Normally presents in childhood/teenage years
- 5x more common in developing countries
Aetiology
- Genetic component
- 30% of patients will have a first degree relative with epilepsy. But in most cases, there is no specific syndrome present
- >200 rare inherited syndromes all have epilepsy as a component
- Developmental abnormalities
- Trauma / Surgery
- Hypoxia
- Pyrexia – particularly in children
- Mass lesion in the skull
- Drugs
- CNS infection
- Vascular abnormalities – particularly in the elderly; including stroke.
- Metabolic disturbance
Pathology
In epilepsy there is an abnormal synchronised discharge of neurons. Normal inhibitory mechanisms fail. Individuals are said to have a seizure threshold – this is the level of excitability at which cells will discharge uncontrollably. In epileptic patients we say that the seizure threshold is lowered, and the neurons are hyperexcitable. The main neurotransmitters involved are glutamate (excitatory) and GABA (inhibitory).
Triggers that push neuron excitation past the seizure threshold are:
- Sleep deprivation
- Alcohol (alcohol intake AND alcohol withdrawal)
- Drug misuse
- Physical/mental exhaustion
- Flickering lights –e.g. on TV/video games - cause primary generalised epilepsy only
- Infection / metabolic disturbance
- Less common:
- Loud noises
- Hot bath
- Reading
- Strange shapes
- Strange smells
- Strange sounds
$(function(){
var pertama = $('#herb-dict .herblist li:first-child').attr('class');
$('#herb-dict .herblist li.'+pertama).show();
$('#herb-dict .alphlist li#'+pertama+' a').addClass('active');
$('#herb-dict .alphlist li a').click(function(){
var target = $(this).attr('rel')
$('#herb-dict .herblist li').hide();
$('#herb-dict .herblist li.'+target).show();
$('#herb-dict .alphlist li a').removeClass('active');
$(this).addClass('active');
});
});
