Advanced Brain Mapping
Froedtert & MCW specialists have played a pioneering role in the development and innovative use of advanced diagnostic techniques to map the functional areas in the brain prior to surgery. These highly specialized tests are performed by interventional radiologists, epileptologists and neuropsychologists. These tests are performed while the patient is awake and reduce the risk of loss of speech and memory functions and help in deciding on surgery as a treatment. This results in a higher level of care for neurology and neurosurgery patients.
Functional Magnetic Resonance Imaging (fMRI)
This specialized MRI scan maps the different types of functions, like language, memory, attention, motor and the visual processes. It provides detailed images quickly and moment-to-moment changes in brain activity. The fMRI allows surgeons to pinpoint the functional areas of the brain and to improve outcomes following surgery.
Routine EEG — as opposed to long-term video-EEG monitoring described below — can be a useful tool in classifying patients' seizure syndrome. But because routine EEG samples only a brief period of time, it is difficult to determine the frequency and type of seizures using this method alone. Video-EEG monitoring provides much more information about patients' seizures and helps physicians determine whether surgery is likely to help.
Video EEG Monitoring
Epilepsy is known as a "historical disease" because doctors generally don't have the opportunity to observe seizures — they have to rely on the patient's description. For some patients with epilepsy, whose seizures respond well to medication, this "historical" information is sufficient. But when medications are not effective (a condition known as refractory epilepsy), a higher level of diagnostic care and treatment is called for.
In such cases, patients are admitted to the hospital for epilepsy monitoring. The term "epilepsy monitoring" refers to the use of simultaneous video-EEG recordings over the course of several days. Because of the time required, this monitoring is performed on an inpatient basis.
The simultaneous use of video and EEG monitoring is needed to verify the presence of epileptic seizures and the localization of the seizure origin. Long-term monitoring helps verify the diagnosis of epilepsy, distinguish different types of seizures, identify the brain region in which seizures begin and quantifies seizures' frequency.
After being admitted to the hospital in the morning, patients are connected to scalp electrodes, escorted to a room in our dedicated epilepsy monitoring unit on the Neurology floor and connected to the video-EEG monitoring equipment. The equipment receives the EEG signal, converts it to a digital signal and records it, along with a digital video image. The electroencephalogram and the video are recorded during several days continuously. During epilepsy monitoring, patients' medication is decreased or sometimes discontinued altogether, in order to increase the probability of recording a number of seizures.
After the monitoring period, the neuropsychologist, neurologist and neurosurgeon review the video-EEG results, along with neuropsychological and neuro-imaging test results, to decide whether patients might benefit from surgery. Patients are informed of the results either before being discharged or during a subsequent appointment. Patients maintain contact with their referring physicians throughout and following their hospitalization.
Magnetoencephalography (MEG) in Epilepsy Patients
Successful surgical treatment depends on accurately determining the region of seizure onset — the epileptogenic zone — and its relationship to functionally important brain areas.
Non-invasive techniques to locate the epileptogenic zone and functional cortex can be of enormous value in guiding epilepsy surgery.
The source of seizures is unique in each person with epilepsy. MEG provides a non-invasive way to localize the areas of the brain that show evidence of electrical irritability with a high spatial precision. The high resolution of MEG also allows the epileptologists to distinguish between areas from which abnormal electrical discharges originate and those to which they propagate. MEG can also be utilized to identify areas important for motor function, language or vision, and their relationship to abnormal areas.
In epilepsy patients, a MEG study can:
- Make it unnecessary to perform an invasive recording of brain electrical activity in some patients, thereby decreasing hospital stays.
- Identify potential areas of electrical abnormalities, and thereby allow better placement of intracranial electrodes in other patients.
- Allow patients to make better-informed decisions about pursuing surgical treatment, given the relationship between abnormal areas and important brain functions identified non-invasively using MEG.
Positron Emission Tomography (PET) and PET/MR
PET scans use a radioactive tracer to measure levels of activity in the brain, which often correlates with areas of seizure involvement. PET/MR combines the technologies of PET and MRI to correlate the functional information of PET with the high-resolution, soft-tissue information from MRI. The Froedtert & MCW Epilepsy Program is the only one in Wisconsin utilizing PET/MR.