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The
physiology of a Seizure
It is important to evaluate the structure and function of nerve
to understand the process of electrical transmission within
nerve cells. A nerve cell is a tube, having an internal section,
bounded by a cell wall or cell membrane. The chemical
compositions inside the cell and the outside of the cell are
different. There will be a specific difference in the
concentration of sodium and potassium salts. Sodium salt
concentration will be higher on the outside, and potassium salt
concentration will be higher on the inside.
When a nerve is called to transmit an electrical signal, a
sudden movement of these salts from one side of the cell’s
membrane to the other occurs. This movement will spread like a
wave from one end of the nerve to the other side of the nerve
until it reaches the end. At this instant, the nerve’s
electrical signal may be transmitted to the next nerve cell by
releasing a special chemical called a neurotransmitter. |
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Neurotransmitters generally have any one among the two special
functions
• One type of neurotransmitter is responsible for encouraging
cell-to-cell communication and is referred to as an “excitatory”
neurotransmitter.
• The second type is able to slow down, or even stops the
cell-to-cell communication and is called an “inhibitory”
neurotransmitter.
In some cases, over activity of excitatory neurotransmitters or
under activity of inhibitory neurotransmitters may create
seizure activity by allowing an uncoordinated flow of electrical
activity in the brain cells.
Many types of abnormal activities in
brain cells are responsible for producing seizure activity.
These abnormal discharges will spread to other cells in a local
area or to remote areas of the brain, resulting in irregular
disturbance to the brain's normal functions. Some changes in
brain biochemistry and communication between brain cells may
occur. This is the basic neurological abnormality that leads to
epilepsy. The condition called epilepsy is created by recurrent
seizures or prolonged seizures, these seizures can cause injury
to the brain. Seizures that last longer than 20 to 30 minutes
can damage the brain’s neurons.
A seizure is divided into different
parts as follows
Aura The aura is a period or
warning earlier to a seizure. Patients suffering from aura may
experience unusual smells, visual symptoms or feelings.
Ictus The seizure itself is
referred in other name as ictus. The period of time that comes
after the seizure is called the postictal state. Seizures were
indicated during the period of prehistoric man, the evidence is
brought from cave paintings.
Incidence Seizure
disorders are the common neurological problems. It has been
estimated that there are more than 4 million people affected
with different forms of epilepsy in United States.
The occurrence of epilepsy has been reduced from the past one
year. There are only 1% possibility for the occurrence of
Epilepsy from birth to the age of 20 and from age 20 to 55, the
possibility of epilepsy further decreases, but after age 55 it
increases drastically.
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Seizure
types
There are more than 40 types of seizure, most of them are
classified under two main categories:
• Partial Seizures
• Generalized Seizures
Partial Seizures: Partial
seizures occur when the excessive electrical activity in the
brain is limited to one particular area. The two most common
forms are simple partial seizures and complex partial seizures.
• Simple partial seizures there will not be any change in
consciousness. Patients suffering with Simple partial seizures
may experience weakness, numbness, and unusual smells or tastes,
twitching of the muscles or limbs, turning the head to the side,
paralysis, visual changes or vertigo. |
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• Complex partial seizures (temporal
lobe) There will be considerable changes in consciousness
Patients may have some symptoms similar to those in simple
partial seizures but have some change in their interaction
ability with the environment. Patients may experience
automatisms (automatic repetitive behavior) such as walking in a
circle, sitting and standing, smacking their lips together,
presence of unusual thoughts such as the feeling of being in
some unknown place, uncontrollable laughing, fear, visual
hallucinations and experiencing unusual unpleasant odors.
Generalized
Seizures: Generalized seizures occur when the
excessive electrical activity in the brain spreads throughout
the entire organ. The three most common forms are generalized
absence seizures, tonic-colonic seizures and mycological
seizures.
• Tonic-clonic (grand mal) Most people associate with this type
of seizures. There will be specific movements in the arms and
legs and/or there will not be any consciousness in. Patients
suffering from this type of seizure may have an aura. The person
will suddenly fall and begin to have jerking movements of their
body and head. Patients may experience drooling, biting of the
tongue and incontinence of urine. When the jerking movement
stops, the patient may remain unconscious for a prolonged period
of time. The seizure usually lasts 5 to 20 minutes. The patients
may experience extended weakness after the event over a period
of time, this is termed Todds paralysis.
• Absence (petit mal) There will be loss of consciousness
without any other dangerous symptoms. Usually there will not be
aura. The loss of consciousness will occur only for short time
and the patient may appear to be involved with the environment
within few seconds and will continue their activity. There will
not be any memory about the event happened.
• Myoclonic Myoclonic seizures are characterized by a brief
jerking movement that occurs from the central nervous system,
usually involving both sides of the body. There are many
different syndromes associated with mycological seizures,
including juvenile myoclonic epilepsy, West syndrome and Lennox-Gastaut
syndrome. This type of epilepsy occur during the first 5 years
of life.
Important facts to remember
There are certain facts to be remembered when we are coming
across seizures:
• A person may stop breathing only for few seconds during a
seizure.
• Most of the seizures exist only for 1-2 minutes, although the
person may be in confused state over a period of time.
• The brain itself always stops the seizures safely and
naturally.
• Once if a seizure begins, we cannot stop it. It should stop by
itself
• Only in the case of emergencies, doctors use some drugs to
bring seizure to an end.
• People experiencing seizure will not have any painful
sensation, but muscles may sore afterwards.
• Seizures are not life threatening, but the risk is increased
in seniors by the extra strain and stress on the heart, the
possibility of injury or a reduced intake of oxygen.
• Seizures are not dangerous to others.
• Seizures are not contagious.
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