Can You Have a Seizure and Not Know It?

Focal onset seizures don't involve convulsions—so look out for these symptoms instead.

Medically reviewed in June 2022

When you think of seizures, you may picture uncontrollable convulsions and loss of consciousness. However, these symptoms do not happen to many people who live with epilepsy or other seizure-producing disorders. 

According to the National Institute of Neurological Disorders and Stroke, about 60 percent of people with epilepsy experience what is known as a focal seizure. When they remain localized to one side of the brain, these seizures lack convulsions—but they're no less serious. If you or a loved one is living with a neurological disorder, it's important to understand the types of focal seizures and their symptoms. 

What are focal onset aware seizures? 

Unlike generalized seizures, which occur on both sides of the brain, focal seizures happen within a small cluster of cells or one area of the brain. They are typically broken down into two types: focal onset aware seizures and focal impaired awareness seizures. Both can progress into larger seizures with convulsions. 

During a focal onset aware seizure (formerly called a simple partial seizure), you remain conscious and often respond to questions and cues. Symptoms can include: 

  • A rising feeling in the stomach 
  • Buzzing in the ear 
  • Tingling, numbness or stiffening of the arms, legs or face 
  • Visual hallucinations 
  • The feeling of déjà vu 

Focal onset aware seizure symptoms will vary based on where it started in the brain. The episode is short, usually lasting for less than two minutes. 

“The patient is aware of the symptoms, is able to follow commands and respond to questions during the event and is able to recall the event later,” Jyoti Pillai, MD, a neurologist at Our Lady of Lourdes Medical Center in Camden, New Jersey. 

These types of seizures are also referred to as auras—a feeling or warning that a larger seizure could be on the way. Dr. Pillai warns that these can sometimes lead to a focal to bilateral tonic-clonic (grand mal) seizure, which involves convulsions. 

What are focal onset impaired awareness seizures? 

In contrast, a focal onset impaired awareness seizure (formerly called a complex partial seizure) can be marked by an altered consciousness—you remain partially aware—or a lack of awareness. You may experience movements called automatisms that include lip smacking, fidgeting or picking at clothing; it may also be associated with stiffening of the limbs. Or, you may just blankly stare into space. 

“The patient is usually confused, is not able to follow commands and is not able to comprehend what is being told to them, although sometimes they are able to hear you,” says Dr. Pillai. 

These seizures can last up to three minutes. After it's through, you may be confused and not remember the event; extreme fatigue and the desire to sleep may also follow. 

Though neither of these seizures present with convulsions, the lack of consciousness that occurs with focal impaired awareness seizures can put people into some dangerous situations. 

“It is important to distinguish focal onset impaired awareness seizures from focal onset aware seizures, because of the risks associated with loss of awareness, including driving and operating machinery, which needs to be restricted in these patients,” notes Dr. Pillai. 

How to respond 

Anyone having a first-time seizure should be evaluated by a doctor. If the seizure is protracted, the person should go to the emergency room. 

If a loved one experiences either type of focal seizure, it’s important to first make sure they are safe. Gently guide them away from any public area to a safe place, or make sure they are in a secure spot within their own home. 

Since a person experiencing a focal onset aware seizure remains alert, they may get upset during or after the occurrence. Stay calm and comfort them during the seizure, offering to get further medical assistance if they need it. 

If someone you know is experiencing a focal impaired awareness seizure, it is crucial to stay with them for the duration of the episode, since they may lack consciousness while a seizure is occurring. Speak calmly and softly, as any loud or aggressive behavior may agitate them. 

“Stay with the patient until the seizure is over, and they are safe and do not appear confused. Some people take longer to recover,” suggests Dr. Pillai. “Medical help should be sought if the seizure is prolonged, usually longer than 5 to 10 minutes or having two back-to-back seizures, without recovery of consciousness between the seizures.” 

If you have had a focal seizure or if these symptoms sound familiar, chat with your doctor. There could be many underlying causes that extend beyond epilepsy. They can rule out similar conditions that mimic the same symptoms, such as migraines or transient ischemic attacks due to decreased blood flow to the brain.

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