Epilepsy: Types of seizures, Symptoms, Pathophysiology, Causes and Treatments, Animation.

Epilepsy is a group of neurological diseases
characterized by recurrent seizures. Seizures happen as a result of a sudden surge
in the brain’s electrical activities. Depending on which part of the brain is affected,
a seizure may manifest as loss of awareness, unusual behaviors or sensations, uncontrollable
movements or loss of consciousness. The brain is a complex network of billions
of neurons. Neurons can be excitatory or inhibitory. Excitatory neurons stimulate others to fire
action potentials and transmit electrical messages, while inhibitory neurons SUPPRESS
this process, preventing EXCESSIVE firing. A balance between excitation and inhibition
is essential for normal brain functions.

In epilepsy, there is an UP-regulation of
excitation and/or DOWN-regulation of inhibition, causing lots of neurons to fire SYNCHRONOUSLY
at the same time. If this abnormal electrical surge happens
within a limited area of the brain, it causes PARTIAL or FOCAL seizures. If the entire brain is involved, GENERALIZED
seizures will result. Partial seizures subdivide further to:
– Simple partial: depending on the affected brain area, patients may have unusual feelings,
strange sensations or uncontrollable jerky movements, but remain conscious and aware
of the surroundings.

– Complex partial seizure on the other hand
involves a loss or changes in consciousness, awareness and responsiveness. Generalized seizures subdivide further to:
– Absence seizures: this type occurs most often in children and is characterized by
a very brief loss of awareness, commonly manifested as a blank stare with or without subtle body
movements such as lip smacking or eye blinking. People with absence seizures may not be aware
that something is wrong for years. Kids who start having absence seizures in
early childhood stand a good chance of outgrow them without treatment. – Tonic seizures are associated with stiffening
of muscles, or INCREASED muscle tone, and may cause the person to fall, often backwards. – Atonic seizures, also known as drop attacks,
on the other hand, are characterized by a sudden LOSS of muscle tone, which may cause
the person to collapse or drop down.

– Clonic seizures are associated with RHYTHMIC
jerking muscle movements. Most commonly affected are the muscles of
the neck, face, arms and legs. – Myoclonic seizures are sudden brief jerks
or twitches of muscles. Patients typically react as if hit by a jolt
of electricity. – The most dramatic are tonic-clonic seizures,
also known as convulsive seizures. These are combinations of muscle stiffening
and jerking. This type is what most people relate to when
they think of a seizure. It also involves sudden loss of consciousness
and sometimes loss of bladder control. A tonic-clonic seizure that lasts longer than
5min requires immediate medical treatment. Epilepsy may develop as a result of a brain
injury, tumor, stroke, previous infection or a birth defect. Generalized seizures that start in childhood
are likely to involve genetic factors.

Epilepsy due to a single gene mutation is
rare. More often, an interaction of multiple genes
and environmental factors is responsible. Hundreds genes have been implicated. Examples include genes encoding for GABA receptors
– major components of the inhibitory circuit, and ion channels. Many genetic disorders that cause brain abnormalities
or metabolic conditions have epilepsy as a primary symptom. The cause of epilepsy is unknown in about
half of cases.

Diagnosis is based on observation of symptoms,
medical history, and an electroencephalogram, or EEG, to look for abnormal brain waves. An EEG may also help in differentiating between
partial and generalized seizures. Genetic testing maybe helpful when genetic
factors are suspected. There is no cure for epilepsy but various
treatments are available to control seizures. Medication successfully controls seizures
for about 70% of cases. Many anti-epileptic drugs are available which
target sodium channels, GABA receptors, and other components involved in neuronal transmission. Different medicines help with different types
of seizures. Patients may need to try several drugs to
find the most suitable. Dietary therapy: ketogenic diet has been shown
to reduce or prevent seizures in many children who do not respond to medication. Ketogenic diet is a special high-fat, low-carbohydrate
diet that must be prescribed and followed strictly. With this diet, the body uses fat as the major
source of energy instead of carbohydrates. The reason why this helps control epilepsy
is unclear.

Nerve stimulation therapies such as vagus
nerve stimulation in which a device placed under the skin is programmed to stimulate
the vagus nerve at a certain rate. The device acts as a pacemaker for the brain. The underlying mechanism is poorly understood
but it has been shown to reduce seizures significantly. Finally, a surgery may be performed to remove
part of the brain that causes seizure. This is usually done when tests show that
seizures are originated from a small area that does not have any vital function..

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