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Diagnosing Epilepsy & Seizure Disorders

Specialists at NYU Langone’s Comprehensive Epilepsy Center have the resources and experience to diagnose the various types of epilepsy and seizure disorders that occur in adults, as well as those seen in children.

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A seizure is an excessive surge of electrical activity in the brain that can cause a variety of symptoms, depending on the parts of the brain involved. Symptoms may include a sudden and involuntary jerk of a hand, an arm, or the entire body. People having a seizure may describe smelling burnt rubber, have a strange feeling in the stomach, hear a ringing sound that becomes louder, or stare into space.

The term “seizure disorder” is often used interchangeably with “epilepsy.” Epilepsy is a neurological disorder that causes a person to have two or more unprovoked seizures more than 24 hours apart. “Unprovoked” means the seizures are not brought on by a clear cause, such as alcohol withdrawal, heart problems, or hypoglycemia, which is when a person has extremely low blood sugar levels.

Seizures may be the result of genetics or of conditions such as brain trauma, tumors, dementia, or stroke. Often, the cause is unknown.

Seizures can last from a few seconds to up to several minutes. Some people may experience an aura, or warning symptoms, just before a seizure begins. An aura may involve smells, emotions, or mental experiences, such as a sense of déjà vu or out-of-body feelings.

An aura may also bring about visual changes, such as blind or dark spots, bright lights, or a distortion in the shape or size of objects. A person may hear sounds or voices or have a sensation of being separated from his or her body.

Any person at any age can develop epilepsy and seizures. Epilepsy is more common in young children and in people older than age 55. Three million people in the United States have epilepsy.

Medical History and Physical Examination

Because doctors seldom witness a person’s seizures, they compile a detailed and accurate medical history to diagnose epilepsy and differentiate it from other conditions.

Epilepsy specialists at NYU Langone conduct a physical exam and ask questions about a seizure, including the following:

  • How did the seizure begin? Was there a trigger?
  • How long did the seizure last?
  • Did a lack of sleep or unusual stress precede the episode?
  • Was the person who had the seizure recently ill?
  • Has this person taken any medications, including over-the-counter medications, alcohol, or illegal drugs?
  • What was the person doing immediately before the seizure? Was the person lying down, sitting, standing, rising from a lying position, or exercising?
  • Did the person lose consciousness or become mentally or physically impaired?
  • What kind of movements were involved—for example, jerking, automatic chewing or hand movements, eye blinking, head turning to one side, loss of bladder control, or a tongue bite?
  • Did the person fall asleep or become confused after the seizure?

Having a family member record information about a seizure can help your doctor to confirm that it was a seizure and determine the type.

Because a seizure may be caused by a medical disorder, a physical exam is an important part of the first consultation. The exam and the results of certain laboratory tests can tell your doctor whether the liver, kidneys, and other organ systems are working as they should.

A doctor also uses other diagnostic tools, including the following, to determine if a person has epilepsy.

Neurological Examination

This exam can help doctors determine whether brain function is impaired. During a neurological exam, an NYU Langone neurologist assesses mental functions, such as the ability to remember words and name objects.

He or she then evaluates your cognition, strength, sensation, reflexes, walking, and coordination. This helps doctors identify patterns of weakness or sensory loss and detect subtle signs of a neurological problem.

Our doctors may order one or more of the following imaging tests to help diagnose epilepsy and seizure disorders.


If a doctor suspects epilepsy is causing your symptoms, he or she may order an electroencephalography, or EEG. This tool is the most specific test for diagnosing epilepsy because it records the electrical activity of the brain.

EEG is a safe and painless procedure in which electrodes are applied to the scalp with a special paste or removable glue. The electrodes are connected by wires to an EEG machine that records electrical activity in the brain for 20 to 40 minutes.

Because the room is quiet and often dimly lit, you may fall asleep during a routine EEG. This is ideal for diagnosis, because an EEG that measures brain activity while you are both awake and asleep may provide additional information.

During the EEG, a technician may ask you to open and close your eyes several times, shine flashing lights into your eyes, or ask you to breathe rapidly or deeply. Sometimes a doctor asks you to stay awake the night before the EEG is performed. Sleep deprivation can increase the likelihood that epilepsy waves, or electrical activity that indicates epilepsy, may be recorded on the EEG.

Ambulatory Electroencephalography

Sometimes the results of a routine EEG are normal or reveal only minor, nonspecific findings. In some people, electrical activity that indicates epilepsy occurs only once every few hours or only after several hours of sleep, and a routine EEG may not capture it. Your doctor may want an extended recording, which includes long periods of wakefulness and sleep.

An ambulatory EEG can record up to 72 hours of brain activity with a special recorder that is slightly larger than a smartphone. This recorder allows you to go about your regular routine. It can be worn on the waist, with the wire running either underneath or outside of your shirt.

Ambulatory EEG can last from 24 to 72 hours. Your doctor may ask you to keep a diary of your activities during the testing period. Most recorders have an “event” button you can press if you experience symptoms of a seizure, such as feeling “spacey” or confused.

Video Electroencephalography

Video EEG monitoring allows the doctor to view your behavior and brain activity. Having access to audio–video and EEG data at the same time lets your doctor match seizure activity in the brain and your symptoms and actions during the seizure.

Using video EEG, your doctor can confirm whether you are having an epileptic seizure and, if so, its type and location in the brain.

Video EEG recordings can be used whether you are in the hospital or at home. When you are in the hospital, technicians can better maintain the recording quality and doctors can safely lower medications or reduce sleep to increase the chances of recording epilepsy waves or seizures.

MRI Scans

A doctor may order an MRI scan—in which a magnetic field and radio waves create computerized two- or three-dimensional images—to better view the structure of the brain. The scans may show any problems that may be causing the seizures. MRIs provide the most detailed and accurate images of the brain.

CT Scans

A CT scan is a type of X-ray that creates detailed images of tissue and internal organs. CT scans can help doctors identify any brain abnormalities that might be causing seizures, such as scar tissue, tumors, or malformed blood vessels. They can also identify any spinal fluid circulation problems.

CT scans are not as detailed as MRI scans, but they are performed quickly and can be helpful during emergencies. They are also used when MRI scans are not recommended, such as in people who use certain medical devices or metal implants.

Single-Photon Emission CT Scans

Single-photon emission CT (SPECT) is an imaging tool that reveals blood flow in the brain.

During the test, a small amount of a radioactive compound is injected into a person’s arm. This material flows into different regions of the brain, and the particles it emits are measured. A large amount of particles indicates more blood flow in a certain area.

The results of the test are displayed as a picture on a computer monitor, with different colors representing different levels of blood flow. If the scan is performed during or immediately after a seizure, it may show increased blood flow in the area of the brain where the seizure occurred.

Computers can compare a baseline SPECT scan to one obtained immediately after a seizure to better show where the seizure originated in the brain.

PET Scans

A PET scan uses small amounts of radioactive glucose, or sugar, is injected intravenously to create a detailed image of the brain. It enables a doctor to view blood flow and brain cell activity and to determine how well the brain metabolizes sugar.

This helps your doctor determine how well the brain is functioning and identify the area of the brain where focal seizures occur. Areas that use less sugar are often the same parts of the brain where these seizures occur.

Magnetic Resonance Spectroscopy Scans

Magnetic resonance spectroscopy uses an MRI machine to analyze the molecular components of tissue in a particular area of the brain. This helps doctors differentiate a seizure from another condition, such as a metabolic disorder, tumor, or stroke. It also gives doctors another way to view the tissue where seizures are occurring.

Functional MRI Scans

Functional MRI uses a standard MRI machine to measure changes in oxygen and blood flow to a particular area of the brain while a person performs specific tasks.

During this test the doctor may ask you to perform a task repetitively, such as reading a short passage, speaking simple words, or moving your thumb. The brain area used for each task is then highlighted on the scan.

By analyzing this data, the doctor can pinpoint areas of the brain that are essential for language, memory, or motor function, which is important when people are considering surgical treatment of seizures.


Magnetoencephalography is an imaging technique used to identify and analyze brain activity. It does this by recording and measuring magnetic fields generated in the brain.

Detectors placed near the head record magnetic waves between seizures, which are then mapped in three dimensions on an MRI or CT image of a person’s brain. This test can help doctors focus on the part of the brain where the seizure is taking place and view it in three dimensions. It can also help map the areas of the brain responsible for movement, sensory function, and language.

Our Research and Education in Epilepsy and Seizure Disorders

Learn more about our research and professional education opportunities.