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What causes seizures?

When the normal functions of the brain are disrupted by injury, disease, fever, infection, metabolic disturbances, or conditions causing a decreased oxygen level, a seizure may occur.

Imagine for a moment that you're behind the wheel, driving up on a four-way stop. Because you have places to be and people to see, you might be a little apt to disregard the rules of the road, which specifies the order of advancing through an intersection. You know that barreling through the stop sign would likely cause an accident with those other drivers who had the right away. Cars would pile up, horns would blare, and your feelings would rapidly change as you start to consider your soon-to-rise insurance premiums and concern for the people in the other vehicles.

Well the brain operates in same way. Most of the time, neurons release ordered electrical pulses about the brain, delivering messages to the rest of the nervous system (spinal cord and nerves). But when all those neurons start triggering at once, the brain experiences a sort of traffic jam. The rapid and wild firing overwhelms the rest of the brain, which results in a seizure.

The majority of the time, the neurons in your brain fire at a rate of about 80 times per second. During a seizure, that rate soars to 500 times per second.

So what causes these electrical storms, these traffic jams? We know what a seizure looks like - the convulsions, twitching, and drooling. But not all seizures are the same.

Focal seizures (sometimes called partial seizures) occur in just one area of the brain and are experienced by about 60 percent of people with epilepsy.

Generalized seizures occur in both sides of the brain.

From a simple pathophysiologic perspective, seizures are caused by abnormal, synchronous, rhythmic electrical activity in the brain. Some seizures are called provoked seizures where one can identify a cause. Some of these causes include:

  • metabolic abnormalities like low glucose, sodium, calcium or oxygen levels
  • structural lesions such as brain tumors, abscess, vascular malformations or cavernomas, hemorrhage, ischemic stroke, head trauma
  • drug intoxication (cocaine, amphetamines, PCP) or withdrawal (barbiturates, benzodiazepines, alcohol)
  • infection (meningitis, encephalitis)
  • fever as an infant

Then there are idiopathic epilepsies which we believe are genetic in nature like juvenile myoclonic epilepsy, absence epilepsy or benign epilepsy with centrotemporal sharps (formerly benign Rolandic epilepsy).

In more than 50% of seizures a cause cannot be found which is thus called cryptogenic.

In some cases, seizures are caused by a medical condition known as epilepsy, but if a person suffers a seizure, it does not necessarily mean that he or she has epilepsy. Seizures can also occur due to a rapid rise or fall in temperature, a tumor, a traumatic injury, an electrolyte imbalance (dehydration), or withdrawal from a medication. Seizures can happen in any sport as a result of injury and dehydration.

(This answer provided for NATA by the Georgia College & State University Athletic Training Education Program.)
Determining the root causes of seizures is critically important, as they can have other causes besides epilepsy. Many people have one or more seizures in the course of their lifetime. These can be caused by head trauma, a brain infection, exposure to chemicals or other causes. There are also conditions that can mimic seizures, such as migraines or fainting.
Seizures can be caused by many things in both normal and abnormal brains. In this video, I will say that prevention is an important part of treating seizures.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.