What Causes Seizures? Triggers, Why They Occur, and More

Medically Reviewed By Heidi Moawad, M.D.
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Epileptic seizures occur due to irregular electrical activity in the brain, affecting brain and body functions. Seizures can have a variety of underlying causes. According to the World Health Organization (WHO), approximately 50 million people globally have epilepsy. This makes it one of the most common neurological conditions worldwide.

While epilepsy is a common cause of seizures, they can also occur for other medical reasons.

This article will discuss seizures, including their causes, triggers, and related conditions. It will also discuss the diagnosis and outlook of seizures.

What can cause seizures?

A person in a dark room is surrounded by colorful fiber-optic lights.
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Epilepsy refers to a neurological condition that causes irregular electrical activity in the brain. It leads to reoccurring seizure episodes, which may have no obvious trigger.

Neurons are nerve cells in the brain that generate electrical and chemical signals. These neurons help to control and regulate your body’s functions. People with epilepsy often have a region in the brain where neurons may send irregular signals. This can lead to seizures.

During a seizure episode, neurons in the brain may send out as many as 500 signals per second. This can cause symptoms such as:

Several types of conditions and injuries can lead to epilepsy. Clinicians organize these into the following categories:

  • Structural differences: Damage to the brain that causes structural changes may result in epilepsy. This can include damage due to:
  • Genetic differences: Congenital and genetic conditions that cause brain malformations may lead to epilepsy.
  • Infection: Infection of the brain from conditions such as meningitis, malaria, or neurocysticercosis can result in epilepsy.
  • Metabolic disorders: Metabolic conditions can sometimes lead to epilepsy.
  • Immune conditions: Conditions affecting the immune system, such as autoimmune limbic encephalitis, can result in epilepsy.
  • Unknown causes: About half of epilepsy cases worldwide have an unknown cause.

Clinicians categorize epilepsy into different types depending on the kind of seizures they produce.

Epileptic activity that occurs in more than one area of the brain may lead to generalized seizures. If the activity occurs in only one area, this can cause focal seizures. Focal seizures may sometimes spread and lead to generalized seizures.

Read more about the types of epileptic seizures and their symptoms.

Provoked seizures

Some types of seizures are not considered epileptic.

A single isolated seizure episode does not qualify as epilepsy. To receive a diagnosis of epilepsy, you must have experienced at least two seizures. According to the WHO, up to 10% of people will experience an isolated seizure during their lifetime.

The Epilepsy Foundation notes that seizures not related to epilepsy can be a symptom other underlying conditions. These can include psychogenic nonepileptic seizures and provoked seizures.

Conditions that may cause provoked seizures include:

  • drug or alcohol withdrawal
  • adverse reaction to a medication
  • meningitis
  • blood sugar conditions
  • high fever leading to febrile seizures
  • brain injury or trauma

Psychogenic seizures are not caused by changes to electrical activity in the brain. Instead, they may be due to psychological conditions or an underlying psychiatric disorder.

Triggers that may cause psychogenic seizures include:

  • high-stress events
  • traumatic events
  • conflict

Understanding whether seizures are provoked or unprovoked can help determine if a person has epilepsy. However, this may be challenging, as people with epilepsy have a higher risk of both types of seizures.

What triggers seizures?

While clinicians may regard epileptic seizures as unprovoked, certain factors can trigger or lead to an epileptic seizure.

The Epilepsy Foundation lists the following factors as potential triggers of an epileptic seizure:

  • sleep deprivation or fatigue
  • stress
  • illness
  • fever
  • hormonal changes
  • low blood sugar
  • dehydration
  • certain foods and ingredients, such as caffeine
  • certain medications
  • flashing lights and patterns
  • high alcohol intake and alcohol withdrawal
  • drug misuse and recreational drugs

Some people may also notice that their seizures follow a pattern, such as occurring at certain times of the day.

When do seizures start?

The onset of seizures can occur at any time. However, they often start during childhood or once a person is over the age of 60. According to a 2022 review, the risk of epilepsy increases in people older than 50 years of age.

The Centers for Disease Control and Prevention (CDC) states that about 3.4 million people in the United States have epilepsy. About 3 million of these cases occur in adults, and around 470,000 in children.

What causes the onset of seizures in adults?

Clinicians refer to seizures that start in adulthood as “adult onset seizures.”

Common causes of adult onset seizures include:

  • stroke
  • infection
  • tumor
  • metabolic conditions
  • brain aneurysms or arteriovenous malformations
  • brain injury

How do doctors diagnose the cause of seizures?

After confirming that you have experienced a seizure, your doctor will try to determine its cause. This involves identifying whether it is epileptic or due to another condition.

To determine the cause of your seizures, your doctor will first ask about your personal and family medical history. This will include questions about any underlying conditions, symptoms you experience, or medications you are taking. Your doctor will also ask questions about your overall health.

During this process, it can be helpful to have someone with you who has witnessed your seizures. They can provide information you may be unaware of if you lost consciousness.

After an initial appointment, your primary care doctor will most likely refer you to a neurologist.

Accurately diagnosing the cause of seizures can take time and may require more than one consultation. The full diagnostic process may include:

  • Neurological examinations: These involve observation to help assess how well your brain and nervous system are functioning. They may also record the functioning of your senses and reflexes to help identify coordination issues.
  • Electroencephalogram (EEG): After an initial visit, a doctor or neurologist may order an EEG. This exam looks for patterns of abnormal electrical activity in the brain. It can help determine which kind of seizures you are experiencing.
  • Brain imaging tests: These can include MRI or CT scans to record images of your brain. They can help to identify or rule out other causes such as bleeding in the brain or a tumor.

Routine health exams and blood tests can also help to rule out causes such as infection.

In some cases, other types of testing may be necessary. For example, if your seizures do not indicate epilepsy, you may need a psychological evaluation. This can help determine whether you may be experiencing psychogenic seizures.

Once you receive a diagnosis, talk with your doctor about your treatment options. They can help you design a plan to manage your condition and avoid any triggers.

Outlook

Epilepsy can cause complications and increase the risk of death. However, treatments can be very effective at reducing these risks. The WHO estimates that up to 70% of people with epilepsy go on to experience a seizure-free life after receiving an accurate diagnosis and effective treatment.

After 2 years without experiencing a seizure, your doctor may suggest stopping anti-seizure medication. They may then recommend lifestyle changes to manage your seizures if they do not have a structural cause or show persistent EEG changes.

Provoked or isolated seizures may not need extensive or long-term treatment if there are no other complications. For example, many cases of febrile seizures do not require medical treatment.

However, provoked seizures due to causes such as a bacterial infection may require antibiotics. Other causes of provoked seizures, such as stroke, can lead to significant complications or lasting damage.

The outlook for provoked seizures will depend on the underlying cause. Your doctor can provide information about what to expect with your specific condition and its treatment.

Read more about the risk of death with seizures.

Frequently Asked Questions

Heidi Moawad, MD, has reviewed the following frequently asked questions.

What can cause seizures?

Causes of seizures include:

  • structural brain differences
  • injury
  • infection
  • stroke
  • genetic conditions
  • certain medications

Seizures can occur due to epilepsy or another condition, such as infection or an autoimmune disorder.

What causes seizures in adults with no history of seizures?

Stroke is the most common cause of epilepsy in adults over the age of 50. Other potential causes include infection, tumors, and metabolic or cerebrovascular conditions.

Summary

Epileptic seizures occur due to irregular electrical activity in the brain. This can result from changes or injury to the brain present at birth or occurring later in life. In some cases, doctors are not sure what leads to the onset of epilepsy.

Certain factors may trigger the onset of an epileptic seizure. These triggers can include certain foods, fatigue, and illness.

Seizures may also be due to causes other than epilepsy. Clinicians refer to these as “provoked” seizures. Provoked seizures may be due to factors such as medication, injury, or illnesses such as infection.

You must experience two or more seizures to receive a diagnosis of epilepsy. Contact your doctor if you experience a seizure. They can work with you to determine the cause.

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Medical Reviewer: Heidi Moawad, M.D.
Last Review Date: 2022 Sep 29
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