The first and foremost important step in the successful management of epilepsy is its accurate diagnosis. Other conditions may be confused with seizures; some that are particularly relevant in the pediatric age group include syncope, staring spells due to inattention and symptoms due to psychological conditions. Once an accurate diagnosis is established, the next step involves identifying the possible cause and pursuing an appropriate treatment option.
- The MRI shows the gross appearance of the brain and therefore can give anatomic and pathological information of the brain.
- Be sure that no medical (non-surgical) options are available. If there are, these would be recommended to you and to your neurologist at home.
- The use of the MRI scan in patients with epilepsy has been aided by FLAIR techniques and High Resolution MRI imaging and MRI volumetrics.
- Fluid-attenuated inversion recovery (FLAIR) improves the contrast and appearance of abnormalities within the brain.
- It is often helpful to make clear contrast between abnormal findings (lesions) and normal findings (Cerebrospinal fluid).
High Resolution MRI
- Obtaining small thin slices through the brain allows the images to be reconstructed to render a 3-D image of the brain.
- This technique is useful in identifying subtle lesion in the brain (i.e. cortical dysplasia) as well as their full extent of involvement.
- After obtaining the high resolution MRI scan, computer software can be employed to calculate the respective volume of a brain structure on one side of the brain and compare it to the size of the same structure on the other side of the brain.
- MRI volumetrics is occasionally used to evaluate the medial temporal structures which are frequently abnormal in a disease called "mesial temporal sclerosis," a frequent cause of medically intractable epilepsy.
- Positron Emission Tomography (PET scan) is frequently used during the evaluation for epilepsy surgery.
- PET scans can give information on the function of the brain. For instance it can give information on how various regions of the brain metabolize glucose.
- Areas which are not functioning well based on PET scan may overlap with the region of brain giving rise to epilepsy.
- So this test is often helpful in confirming the epilepsy syndrome and occasionally helpful when previous testing have not been able to localize the onset of the epilepsy to one region of brain.
- Areas of brain which do not metabolize glucose well may reflect the dysfunctional region of brain giving rise to seizures.
Ictal SPECT Scan
- Single photon emission computed tomography measures the relative blood flow in various regions of the brain.
- This particular neuroimaging tests brain blood flow information at a specific moment in time.
- The point in time the test reflects is the time in which a particular pharmacologic tracer is injected.
- When the tracer is injected soon after the onset of a seizure, information of blood flow during a seizure can be obtained.
- Ictal SPECT is therefore another functional neuroimaging test which reflects regional blood flows during seizures.
- Areas which light up during this test may reflect the area of brain in which the seizures begins.
- Magnetic resonance spectroscopy uses techniques from MRI imaging to give quantitative chemical information of the brain.
- The information is usually displayed graphically. Various amounts of specific chemical are evaluated to look for too much or too little of specific chemicals in specific regions of the brain.
- This information looks for an abnormal chemical signature in one region of brain which again can be useful in the evaluation for possible epilepsy surgery.
Most pre-surgical patients typically complete neuropsychological testing. Neuropsychology is the study of the brain and behavior. Different regions of the brain are associated with different thinking skills. Neuropsychologists have developed tests that measure a variety of thinking skills such as language, attention, problem solving, and memory. In addition, neuropsychological testing includes measures of emotional and behavioral functioning. A child's pattern of strengths and weaknesses on neuropsychological testing can provide an indication of how well different regions of the brain are working. Neuropsychological testing is useful in the pre-operative evaluation of epilepsy surgery candidates for three reasons:
- to establish a baseline of function from which to evaluate changes following surgery;
- to identify potential regions of brain dysfunction that might be related to the seizure focus;
- to assist in determining potential risks to thinking skills associated with epilepsy surgery.
In addition, information from a neuropsychological assessment can be very useful for the schools in identifying the most appropriate teaching strategies.