Diagnostic Testing for Epilepsy Patients

Cincinnati Children’s is one of the only pediatric hospitals in the United States to offer the full range of diagnostic tests to evaluate pediatric epilepsy patients.

Diagnostic Technologies

Brain physiology and imaging studies help physicians determine whether a child is a good candidate for epilepsy surgery. They also can help doctors plan surgery so that they remove only damaged brain tissue while avoiding healthy tissue. Diagnostic technologies include:

Video electroencephalogram (VEEG) is a painless, noninvasive test that records the electrical activity in the brain by using electrodes attached to the scalp. The child is videotaped while during the test, which allows the doctor to see how the child’s behavior during seizures is related to the brain’s electrical activity.  We perform this test for 24 hours, up to five days in a row in the child’s hospital room.

A VEEG uses up to 32 electrode channels to collect data. Our team sometimes recommends a geodesic EEG, a test that uses up to 256 electrode channels.

Magnetic Resonance Imaging (MRI) uses large magnets, radio waves and a computer to create detailed pictures of structures inside the body, including the brain. MRI helps determine if there is an irregularity in the brain, such as tissue scarring, a malformation, infection or a tumor that is causing seizures.

An MRI scanner is a large magnet with a circle-shaped opening.  Some people say it looks like a tunnel. The child lies down on a table that slides into the scanner. If the child is not able to remain still during the test, he or she may be sedated.

During the test, the scanner makes very loud noises. The technologist is able to talk with the child and tell him when the noises will occur and how long they will last.  Parents are welcome in the scan room during the test. 

Single photon emission computed tomography (SPECT) helps pinpoint the area causing seizures by showing where there is increased blood flow in the brain. There are two kinds of SPECT scans:

  • Ictal SPECT:  a procedure done while a seizure is occurring
  • Inter-ictal SPECT: a procedure done between seizures

 At the child’s bedside, we inject a small amount of a medication, called an isotope, through an intravenous (IV) line into a vein. The isotope is carried to the brain through the bloodstream and lasts for six hours. It does not cause seizures. It travels to the place in the brain where there is greatest blood flow, which may be the location of the seizure.

For an ictal SPECT, we inject the isotope during a seizure. For an inter-ictal SPECT, we inject the isotope between seizures; this can be done during an outpatient visit. After the injection, the child will lie flat on a special table that will slide into the scanner.

About Subtraction Ictal SPECT Co-Registered to MRI (SISCOM) 
SISCOM is an important process that helps locate the focus of seizure activity. Doctors use it to compare the ictal and inter-ictal SPECT scans with MRI images, and to create a three-dimensional brain image. This image highlights the areas of increased blood flow, thus helping determine the area of seizure focus. 

Positron emission tomography (PET) is a type of test that measures metabolic activity within the brain cells. PET can show biochemical changes taking place in the brain that can cause seizures.

During the test, the child lies on a table that slides into the PET scanner. A small amount of glucose-based material is inserted into an intravenous line.  Once the material reaches the brain, the PET scanner shows where cell activity is (and isn’t) taking place. Decreased cell activity (or “cold spots”) suggests possible areas of seizure activity. 

Magnetoencephalography (MEG) monitors the electrical activity of the brain, using magnets to accurately detect the seizure focus. It is one of the newest non-invasive tests available for studying epilepsy and brain function.

During a MEG test, the child lies still with his or her head inside a helmet that contains hundreds of sensors, and may be given a light sedative to cause drowsiness. During the scan, the patient may be asked to perform a specific task, such as reading, looking at pictures or pressing buttons. MEG scans show which area of the brain is active while these tasks are being performed, providing doctors with a detailed understanding of a child’s brain activity.

MEG and video electroencephalography (VEEG) both measure brain activity. However, MEG measures magnetic fields and brain activity produced by neurons, while an EEG records electrical activity in the brain. MEG is a more accurate testing method than VEEG.

A functional MRI (fMRI) uses a safe magnetic field to create images of the brain while it is at work. An fMRI can show doctors which parts of the brain are involved in different mental processes, such as language, movement and vision. Test results help doctors plan surgery by identifying where the brain’s critical structures are located.

The test takes place in the MRI scanner. During the test, the child usually is awake and asked to participate in tasks, such as looking at a picture or listening to music.  fMRI software maps where brain activity occurs when the child is performing these tasks. 

Like a functional MRI, transcranial magnetic stimulation (TMS) identifies functional areas of the brain, especially language and movement areas.  Test results can help doctors plan surgery by identifying where the brain’s critical structures are located.

During the test, the child sits in a chair or on the parent’s lap. The technician places electrodes on the child’s skin, including on the arm, face and leg. The child watches a screen to see pictures or words that should trigger a response, and interacts with the neurologist. The neurologists holds a wand, and uses it to deliver a “pulse,” or several pulses, of electromagnetic energy to the scalp, targeting specific brain regions.

Each pulse only lasts a few seconds, and causes a vibration on the child's scalp. The equipment makes loud noises during the test.

Neuropsychological Evaluation

Neuropsychological evaluations test abilities such as cognition, language, visual-spatial skills, memory, problem solving, motor skills and behavioral functioning.

Neuropsychological evaluations help our team:

  • Understand how epilepsy may affect the child’s behavior and abilities
  • Identify problems such as anxiety, depression and learning difficulties
  • Recognize side effects from epilepsy medication

Neuropsychological evaluation is best done early in a child’s treatment to help establish a baseline. Then, it is often repeated at regular intervals to help our team monitor how the child is doing.  Results help us make recommendations for a child’s individualized education program (IEP) or 504 plan for school.

Depending on the child’s age and ability, evaluations last two to six hours.

Genetic Testing and Counseling 

About 40% of all epilepsy is thought to be due to a genetic cause. Genetic test results can help guide treatment decisions, and indicate whether a child’s siblings or future children might also be at risk for epilepsy. Genetic testing is sometimes definitive, but not always.

Our genetic counselors can:

  • Review the child’s medical history and family medical history
  • Talk about genetic tests that could be useful
  • Schedule and coordinate genetic testing
  • Explain what genetic test results mean
  • Work with the multidisciplinary team to adjust treatment based on genetic test results
  • Follow up with families when new genetic tests are available