What is a Seizure?

Generally, a seizure is the result of a sudden abnormal electrical activity in the brain. In some cases, this can be traced to a specific cause or trigger. In other cases, a cause can’t be identified, but the seizures can still be treated.

Isolated seizures are generally a symptom or indicator of another condition, such as a brain injury or disease (like epilepsy, metabolic disease, etc.), stroke or certain illnesses.

Signs & Symptoms

What Happens During a Seizure?

When they see the word “seizure”, many people think of a full-body episode with loss of consciousness and involuntary jerking or twitching of the muscles. While this type of seizure does exist (called a tonic-clonic seizure, or a grand mal seizure in the past), seizures can actually involve a wide range of symptoms, depending on their type.

Focal onset seizures (previously called partial seizures) start in one area, or side, of the brain and may spread to other areas of the brain.

During these seizures, the person may or may not lose awareness of their surroundings. The seizure may begin in an aware state and progress to a state of impaired awareness (previously a complex partial seizure).

Depending on what area of the brain is affected, symptoms may include:

  • Rhythmic “jerking” movements confined to a specific body part, such as a hand or arm
  • A sudden change in sensory awareness and/or strange sensations such as tingling or flashing lights, often referred to as an “aura”
  • Compulsive hand-rubbing, swallowing, picking at clothing or other repetitive movement with no purpose (called “automatisms”)

Generalized onset seizures, by contrast, affect both sides of the brain at the same time. This type of seizure is characterized by a loss of awareness, but may or may not involve motor symptoms like:

  • Complete loss of muscle control (atonic seizures)
  • Stiffening of muscles (tonic seizures)
  • Muscle twitching or jerking movements (clonic or myoclonic seizures)
  • Automatisms like hand-rubbing, lip-smacking or chewing

Tonic-clonic seizures (previously known as grand mal seizures) are generalized seizures with both tonic (muscle stiffening) and clonic (muscle jerking or spasming) characteristics.

These seizures usually last 1-3 minutes, beginning with a tonic phase and followed by a clonic phase, before the person relaxes and slowly regains consciousness.

Absence seizures (previously known as petit mal seizures) are generalized seizures without any motor symptoms.

Their symptoms can be very subtle, such as simply “zoning out” and staring blankly with a momentary loss of awareness. They typically last only a few seconds and can occur several times throughout the day.


What Causes Seizures?

While some seizures can’t be traced to a clear cause (called unprovoked or unknown onset seizures), acute symptomatic seizures (those with a clear cause) are more common than you may think.

Seizures can occur as a result of a wide range of medical conditions, including:

  • Brain tumors
  • Head injury
  • Stroke
  • Meningitis or encephalitis
  • Low blood sugar associated with diabetes or abnormal electrolytes (blood minerals)
  • Brain malformation or lack of oxygen during birth (infants)
  • High fever or infection (infants and children)
  • Alcohol or medication withdrawal

Seizures may also occur due to an adverse reaction to prescription medications, illegal drug use, alcohol withdrawal or extreme intoxication.

In rare cases, they can also be triggered by psychological factors, such as depression, anxiety and other conditions.

What’s the Difference Between Epilepsy and Seizures?

It’s a common misconception that seizures and epilepsy are synonymous. While all people with epilepsy have seizures, not all people who have seizures are epileptic. In general, an epilepsy diagnosis is only made when a person has had two or more unknown onset seizures more than 24 hours apart or after a single seizure with an abnormal EEG.

Learn more about epilepsy

Care & Treatment

What Should I Do if I See a Person Having a Seizure?

First, don’t panic. Most seizures do not require emergency medical attention. Stay with the person until the seizure is over, moving any hard or sharp objects away from them to minimize the risk of injury, and protect their head by rolling them to one side if possible. Many people will be confused and disoriented after a seizure, so help them to a safe place to recover.

If the person is having a tonic-clonic seizure (previously known as a grand mal seizure), ease them to the floor and cushion their head with a pillow or item or clothing. You can also move them onto their side for easier breathing, and remove or loosen items like neckties or glasses.

Do not attempt to hold the person down, open their mouth or put anything in their mouth, or administer CPR.

When Does a Seizure Require Medical Attention?

If you have never had a seizure before, or if a seizure lasts more than 5 minutes, is followed immediately by a second seizure or is accompanied by another high-risk condition (such as high fever, heat exhaustion, diabetes or pregnancy), seek medical attention immediately.

If you see another person have a seizure and fail to resume breathing or regain consciousness afterward, or an injury occurs during the seizure, call emergency services.

Can Seizures Be Treated?

Yes. However, because some seizures are isolated events, your doctor may not recommend treatment unless you have more than one.

Dietary therapy and stress reduction can help with seizure control for some people. In some cases, however, doctors will prescribe anti-seizure medication to help limit seizure frequency.

If medications alone aren’t effective, your doctor may recommend a surgical treatment (such as vagal nerve stimulation or laser ablation, or surgical resection).

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