Diagnostic Tests

Medical tests can be extremely frightening and stressful for a child. To ease the child's fears and prepare him/her for medical tests, parents should provide as much information as possible in a way that the child will be able to understand.

The child should know:
• why s/he is going for the test
• where the test will take place
• what will happen during the test
• who will be the people involved in the testing, and
• what medical equipment will be used.

Parents should be supportive and listen to their child's concerns. They should validate their child's feelings by acknowledging and discussing any fears the child may have.
 


Diagnostic Tests

Blood Tests
Computerized Axial Tomography (CT or CAT) Scan
Electroencephalogram (EEG)
Functional MRI
Magnetic Resonance Imaging (MRI)
Magnetic Resonance Spectroscopic Imaging (MRSI)
Magnetoencephalography (MEG)
Magnetic Source Imaging (MSI)
Neuropsychological Tests
Neuropsychometric Tests
Positron Emission Tomography (PET)
Single Photon Emission Computerized Tomography (SPECT)
 

 

Electroencephalogram (EEG)

The EEG is the primary diagnostic tool for epilepsy. It is a non-invasive diagnostic test which records the electrical impulses from the brain. Doctors are able to differentiate between normal and abnormal brainwave patterns. However, not all abnormal wave patterns indicate brain disease or injury.
The child's physician may advise the parents to wash the child's scalp the night before the test. The child's scalp must be clean and oil-free so that electrodes used during the test will work effectively.

On the day of the test, the child should eat normally and take all medications as prescribed. Eating before the EEG will help stabilize the child's blood sugar level.

If the doctor has ordered a sleep test, the child may have to adjust his/her sleep schedule prior to the test.
During the test, a number of electrodes will placed on the child's scalp using a conductive gel. This process takes approximately 15 to 20 minutes. The doctors may use various procedures (hyperventilation, sleep, photic stimulation) during the test to stimulate the brain and trigger certain brain waves. The EEG test usually takes 60 to 90 minutes.

 

Magnetoencephalography (MEG)/Magnetic Source Imaging (MSI)

The MEG test records magnetic waves, much the same as an EEG records electrical brain waves. This test is used to assess the function of brain tissue.

 

Magnetic Resonance Imaging (MRI)

The MRI is a non-invasive scanning technique. Magnetic fields and radio waves are projected toward the brain and interpreted by a computer to form detailed two or three dimensional pictures of the brain. MRI can detect very subtle abnormalities of the brain which CT scans cannot record.
Prior to the test, the child should eat normally and take all medications as prescribed.
At the hospital, the child must remove jewellery, hairpins, glasses, and other metal objects. The child will also be asked to change into a hospital gown. The child will be positioned on a scanning table with his/her head positioned on the head rest. When the table slides into the magnetic chamber, the child must lie still as the images are taken. The child won't feel anything but s/he will hear noises from the machine (as radio waves are emitted and the machine moves). It is important for the child to know about the noise in advance so s/he will keep still and not panic.
The MRI procedure usually lasts for 30 to 90 minutes.

Magnetic Resonance Spectroscopic Imaging (MRSI)

An MRSI scan is similar to an MRI scan. An MRI scan looks at the signals detected from protons of water; an MRSI scan looks at the signals detected from many other proton-containing metabolites.

 

Computerized Axial Tomography (CT or CAT) Scan

The CT scan uses low radiation X-rays and a computer to produce a three dimensional image of a brain cross-section. This test is not as sensitive as an MRI scan and is therefore used to detect more obvious brain damage or abnormalities (distortions of the skull or brain) which may cause seizures.
The child may be asked not to eat or drink 4 to 8 hours before the test if a contrast medium (dye) is going to be used.
At the hospital, the child will be asked to put on a hospital gown. Then, s/he will be positioned on the examination table. The child's head will be placed in a cradle-like "pillow" with a strap. Securing the child's head prevents it from moving, to produce a clearer CT scan. Contrast medium may be given orally or injected through the child's hand or arm. The dye will travel through the blood to the child's brain, where it will highlight certain structures to make the image easier to read. The child will be moved into the scanning machine by the technician who sits in an adjacent room. The child must lie still on the table as a rotating X-ray machine takes pictures of the brain from different angles. While the machine scans the child's head, it will produce different sounds. It is important for the child to know about the noise in advance so s/he will keep still and not panic.
The CT scan usually lasts 15 to 20 minutes.

 

Positron Emission Tomography (PET)

PET imaging provides information about the functioning of the brain, including cerebral blood flow, blood volume and neuron metabolism. This is accomplished by injecting radioactive chemicals into the body. When these chemicals reach the brain, they can be visualized and interpreted by a computer.

 

Functional MRI

The functional MRI is similar to PET imaging in that both provide information on active brain tissue functioning and blood delivery. However, the functional MRI is more precise in temporal and spatial resolution. It is an ideal tool in pre-operative planning because it helps physicians identify the exact location of the source of the seizures.

 

Single Photon Emission Computerized Tomography (SPECT)

A SPECT scan works the on the same principle as PET imaging, but is more efficient in distinguishing the area of the brain which is the source of the seizures. A SPECT scan can help to locate the site where a seizure originates, can confirm the diagnosis of a seizure type, and can help in the evaluation process for surgery.

 

Blood Tests

Blood tests are very useful. They can be used to determine the health of the liver and kidneys, vitamin deficiencies, and toxin or chemical abnormalities. A lumbar puncture can be used if it is suspected that an individual has encephalitis or meningitis. Results of these tests can help physicians determine if there is an underlying cause responsible for an individual's seizures.

 

Neuropsychological or Neuropsychometric Tests

Neuropsychological or neuropsychometric tests may be used to assess a variety of brain functions (memory, language, and spatial perception). These tests may be used as pre-surgery tests or may help physicians identify which type of epilepsy an individual is experiencing.
 

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Last Modified: 07/17/2006 01:06:02 PM