The answer to the question what is a seizure, is not just the definition (what it is). It also includes 5 other elements that begin with the letter W. They are where, why, when, and which. Where has to do with the location. When refers to time factors. Why relates to the reason seizures occur. The fifth W refers to the different ways in which a seizure can present itself. The final W pertains to who is having the seizure.
A seizure is an abnormal electrical event with outward and/or inward manifestations. The brain is where it begins. It starts out as a surge of signals discharged by a group or groups of neurons.
There are two reasons why this electrical brain storm, if you will, occurs.
- Something triggers it in the setting of a normal threshold.
- Something lowers the threshold so that a factor that is not usually a trigger becomes one. That trigger is often not identifiable though.
The threshold is the amount of stimulus from a trigger that it takes to produce a seizure.
Common triggers are the following:
- head trauma
- a stroke
- brain tumor
- brain surgery
- brain hypoxia
- fever in children
- CNS infection
- flashing lights
- sleep deprivation
- alcohol consumption or withdrawal
- certain drugs
- the active phase of multiple sclerosis or other autoimmune diseases
- metabolic derangements (chemical imbalances) such as hypoglycemia, hyponatremia, hypocalcemia and uremia
Some factors that cause brain injury might not trigger an acute event. But they might cause a person to be susceptible to seizures in the future, of which the trigger is a different factor which might be unknown.
The ways in which a seizure manifests
A seizure can rear its head in many ways – no pun intended. Which signs and symptoms it displays depends on where in the brain the electrical chaos occurs; which particular function(s) that area of the brain serves; and who is having the seizure.
The brain has many functions. It controls movement, sensation, awareness, cognition, and emotions. The effect of a seizure on a function(s) depends on where in the brain it occurs. The effect on a function produces activity or an experience linked to the function. The activity or experience can be, either or, a combination of the following:
- Motor – pertaining to movement
- Sensory – pertaining to perception with either of the five senses
- Autonomic – pertaining to the autonomic nervous system
The activity or experience that results from the misfiring of brain cells is not the normal type. It is either or a combination of the following:
- chaotic – disorganized
- exaggerated – abnormally increased
- attenuated – diminished
- purposeless – serving no purpose
There are different stages of a seizure. They are the beginning, middle and ending. Other names for them are the aura, ictal and post ictal stage. They signify the periods of time when certain signs and symptoms which occur are present.
The aura is the warning or the first symptom to appear. It might be a change in sensation, emotion, behavior, or thoughts but it is often difficult to describe. It precedes any motor activity that might follow. Not every person or type of seizure has an aura though.
The ictal stage is the middle part of a seizure. It is the time period from the onset of the first signs or symptoms (including an aura) until seizure activity ends. It correlates with the frame of time when abnormal electrical activity is ongoing in the brain.
Sometimes signs and symptoms might last longer than the seizure activity apparent on an EEG. The reason is some are aftereffects not directly related to the electrical disturbance in the brain.
The duration of the ictal stage is usually two minutes or less. If the ictal stage lasts longer than five minutes or recurs back to back without recovery in between a state of status epilepticus exists. It can be life-threatening. Thus, it warrants emergency treatment.
Signs and symptoms of a seizure vary depending on the type and who is having the seizure. But in general they fall under one or more of the following categories:
- Abnormal movements
- Alteration of consciousness or alertness
- Unusual sensations
- Abnormal thoughts
- Impaired cognition
- Strange behavior
Post ictal stage
The postictal stage is the recovery period which begins when the ictal stage is no longer present. It may last anywhere from minutes to hours, depending upon the type of seizure, where in the brain it occurred, and who experienced it. A number of signs and symptoms might be present. But people often report not feeling like themselves until it has ended.
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