What is a Seizure?

What is a Seizure?

A seizure is caused by a sudden firing of uncontrolled electric signals in part of the brain. A seizure can go undetected or, in severe cases, can cause convulsions or unconsciousness.

Seizures affect anyone at any age. The abrupt change in brain activity can be caused by several reasons and can vary greatly in severity and length, which ranges from 30 seconds to two minutes, on average.

Many types of seizures are treatable with medication. Understanding the symptoms and causes of repeated seizures can help you and your doctor determine a course of action and minimize the impact of seizures on day-to-day life.

Types of Seizures


There are many types of seizures, divided into two primary categories: generalized and focal. Seizures are categorized based on the area of the brain in which the surge of abnormal activity occurs.

Generalized seizures

Generalized seizures occur throughout the entire brain, involving both sides (hemispheres). They are broken down into the following subtypes:

  • Tonic-clonic seizures. Formally known as “grand mal seizures,” this type of seizure tends to be severe, causing body shakes, abrupt stiffening of the arms and legs, loss of bladder control, biting of the tongue, and unconsciousness. They can last between one to three minutes.
  • Tonic seizures. These seizures generally cause stiffening of the back, leg, and arm muscles. Usually lasting 10 to 30 seconds, you may lose consciousness and collapse to the ground.
  • Clonic seizures. Clonic seizures manifest as jerky, repeated muscle movements. The rhythmic twitches typically occur in the face, neck, and both arms, lasting 30 to 60 seconds.
  • Absence seizures. Previously known as “petit mal seizures,” absence seizures may only last for a moment but can occur dozens to hundreds of times a day. These mini-seizures may be associated with lip-smacking and blinking. They are more prevalent in children and are often misinterpreted as daydreaming or “spacing out.”
  • Atonic seizures. Atonic seizures (or drop seizures) cause an abrupt drop of the head or a collapse due to sudden muscle control loss. These seizures can lead to severe injuries, including head injuries due to an abrupt collapse caused by loss of muscle tone.
  • Myoclonic seizures. These seizures involve quick jerks or twitches of the legs and arms, with no loss of consciousness.

Focal seizures

Focal seizures usually occur in a small brain area on only one side (hemisphere). Previously referred to as partial seizures, they are generally categorized into two types:

  • Focal seizures with preserved awareness (previously called simple partial seizures). During these seizures, the person does not lose consciousness but may experience a feeling of déjà vu, muscle tightening, numbness, tingling, nausea, hallucinations (smells, sounds), or severe panic. Sometimes the person may have intact awareness but an inability to communicate.
  • Focal seizures with impaired awareness (previously called complex partial seizures). These seizures are similar to focal seizures with preserved awareness but involve some form of loss of awareness or disorientation and an inability to communicate, which can last for a few minutes. People experiencing this kind of seizure may develop a blank stare and repetitive moments such as blinking, lip smacking, finger movements, grunting, or shouting and typically have memory loss during the episode.

Epilepsy is a condition that involves having recurring seizures, or a single seizure, followed by tests revealing an increased risk of recurrence. An epileptic seizure can happen in any area of the brain, with temporal lobe seizures being the most common.

A breakthrough seizure occurs when a person with epilepsy has had seizure freedom (no seizures) for a while and then experiences another seizure.

Signs & Symptoms of Seizures


The symptoms and signs of a seizure depend on its type (focal or generalized seizure) and the level of intensity, ranging from mild to severe.

Some people can sense when a seizure is coming. This precursor period is actually a focal seizure affecting one side of the brain, referred to as an “aura.” Seizure warnings signs (an aura) may involve:

  • Distorted vision
  • Seeing bright lights
  • Hearing sounds that aren’t there
  • Unexpected smells or tastes
  • Strange sensations on the skin
  • A surge of emotion — fear and anxiety or excitement and joy
  • Déjà vu
  • Sweating
  • Salivating/drooling
  • A rising feeling in the stomach
  • Paleness or reddening of the skin
  • Nausea

Depending on the type, symptoms of a seizure can include:

  • Uncontrollable twitching or jerking of the legs and arms or other body parts
  • Stiffening of the muscles and limbs
  • Staring spells with or without lip-smacking
  • Rapid blinking
  • Loss of awareness
  • Loss of consciousness
  • Biting of the tongue
  • Crying or screaming
  • Loss of bladder/bowel control
  • Collapsing to the ground

The defining symptom of epilepsy is recurrent seizures. There is no radical difference between seizure symptoms in adults and children.

Seek immediate medical assistance if any of the following occur:

  • The seizure lasts longer than five minutes
  • A second seizure occurs promptly after the first
  • Consciousness or breathing doesn’t return after the seizure is over
  • The person has a high fever
  •  The person is suffering from heat exhaustion
  • The person is pregnant
  • The person has diabetes
  • The person has sustained an injury (particularly to the head) during the seizure

 Daughter trying to wake unconscious father lying on the floor


What Causes Seizures?


Doctors know that seizures occur from a disruption in the communication pathways of nerve cells in the brain, causing a burst of abnormal activity, like a strand of holiday lights suddenly blinking in a wild sequence.

Epilepsy is a disorder that commonly causes seizures, but not all seizures are caused by epilepsy. What triggers seizures varies from person to person.

Causes of seizures can include:

  • High fever
  • Infection, such as meningitis
  • Lack of sleep
  • Flashing lights
  • Trauma to the head
  • Certain medications
  • Recreational drug use
  • Low sodium levels (hyponatremia)
  • Low glucose levels (hypoglycemia)
  • Sepsis

Risk Factors for Seizures

Risk Factors

No one is immune from seizures, but some risk factors can increase the likelihood of having them. In addition to epilepsy, other risk factors for seizures include:

  • Brain tumors
  • Brain infections
  • Past head injuries
  • Heart disease
  • Strokes
  • Preeclampsia
  • Liver or kidney failure
  • Malignant hypertension
  • Dementia
  • Brain malformations
  • Genetic disorders

How to Prevent Seizures


Certain medications and lifestyle choices can help reduce the risk of seizures including:

  • Taking seizure medication as prescribed without missing doses
  • If sensitive, avoid flashing lights
  • Refraining from using drugs and alcohol
  • Maintaining a healthy sleep schedule
Get Care

Trust NewYork-Presbyterian for Seizure Care

NewYork-Presbyterian is home to world-renowned neurologists, well-versed in identifying symptoms of seizures and other neurological conditions, including epilepsy.

If you or a loved one has experienced signs of a seizure, reach out to our team today to learn more about the condition and receive an expert diagnosis.