jerking of limbs, losing consciousness and awareness,
and psychically fear, anxiety, or deja vu. However,
patients with different types of epilepsy may have
some of these symptoms. And even if two patients
have the same kind of epilepsy, the symptoms
between them may be totally different. For example,
generalized tonic-clonic seizures are the most well
recognized, also called ‘grand mal seizures in the
past. When these seizures happen, the first symptom
is a sudden loss of consciousness, and then the body
would become stiff, followed by jerking of the
muscles. And often, patients may turn red or blue, bite
their tongue, and lose control of the bladder, but these
symptoms vary with each individual. In addition, the
symptoms of generalized absence seizures are much
milder and briefer than generalized absence seizures,
although they belong to generalized seizures. The
symptoms of generalized absence seizures involve
staring, loss of expression, unresponsiveness, and
stopping activity. And sometimes, the patients with
generalized absence seizures just show eye blinking
or upward eye movements.
2.4 The Risk Factors of Epilepsy
Epilepsy is a complex disease with many causes, and
seizures can be led by caused by anything that
disrupts the normal electrical patterns of the brain.
Epilepsy has no identifiable cause in about half the
people with the condition. In the other half, the
condition may be traced to various factors, including
genetic influence, head trauma, brain conditions,
infectious diseases, prenatal injury, and
developmental disorders. First, epilepsy is considered
a high genetic disease, and under many conditions,
epilepsy can be heritable. For example, in idiopathic
generalized epilepsy, the first-degree relatives of
epilepsy patients have an 8-12% risk of developing
epilepsy, which is much higher than the risk in the
general genetic component. Then head trauma is
related to epilepsy, and the recurrent seizure disorder
because of injury to the brain following head trauma
is called Posttraumatic epilepsy (PTE). Studies
showed that traumatic brain injury makes up about
10-20 % of symptomatic epilepsy in the general
population and 5% of all epilepsy. Third, infectious
and infestations are one of the most common risk
causes for seizures and acquired epilepsy and maybe
the most common preventable risk factor for epilepsy
worldwide, especially in resource-poor countries.
Many types of infectious diseases can develop
seizures, ranging from toxoplasma in the newborn,
early childhood infection with human herpesvirus
(HHV)-6 to Creutzfeldt-Jakob disease (CJD) in the
elderly. And seizures maybe just one symptom in
some infectious diseases such as neurocysticercosis
(NCC). Then, prenatal injury can also result in
epilepsy, which is brain damage before babies’ birth
that could be caused by several factors, such as poor
nutrition or oxygen deficiencies. Finally, sometimes
epilepsy can have linkage with developmental
disorders, such as autism and neurofibromatosis.
2.5 The Brain Activity of Epilepsy
The brain activity of epilepsy is the key to a cure for
epilepsy. By researching the brain activity of
epilepsy, scientists can know better the mechanism of
action of epilepsy, influencing factors, and so on,
which provides some new ideas to find the cure
methods for epilepsy. Because the brain activity of
epilepsy is hard to observe and some moral and
ethical barriers and so on, the research of the brain
activity of epilepsy is not very rich and impeccable. It
is hard to observe the brain activity directly, and
scientists have to use some roundabout methods to
research the brain activity of epilepsy, for example,
using the method that compares with the healthy
control group. The main method to detect brain
activity is using a series of scientific instruments,
such as electroencephalography (EEG), magnetic
resonance imaging (MRI), High-density
electroencephalography. EEG is used to record the
brain's electrical activity, which is also the most
common and basic method of detecting epileptic
activity. But although EEG has high temporal
resolution and sensitivity, it is less spatial resolution
and is not sensitive to an activity deep in the brain.
Moreover, EEG can only detect abnormal signals
when the seizure happens, so EEG also has some
imperfections. MRI is often used cooperatively with
EEG to make the detection method more impeccable
because of its better spatial resolution. To be sum,
these are only short-term brain activities.
2.5.1 Short-term Brain Activity
The brain activity of epilepsy researching can be
divided into short-term changes and long-term
changes. The most obvious brain change for short-
term brain activity is the repeated occurrences of
sudden excessive or synchronous discharge in the
cerebral cortical neuron. These discharges can be
detected by EEG and be used to help doctors make a
diagnosis of epilepsy. The EEG of epilepsy which is
different from normal EEG, is called epileptiform
discharge, and it occurs in up to 98% of patients with
epilepsy depending on age and epileptogenicity. The