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Epilepsy Investigations

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EEG/VEM

MRI (Magnetic Resonance Imaging)

SPECT and PET

Neuropsychology

Epilepsy Surgery
Austin Health: Neuroscience Investigations

 

EEG/VEM

Figure 1. EEG tracing

EEG (electroencephalography) records the electrical activity of the brain. It is useful for investigation for patients who have had a seizure and for management for patients with epilepsy.

Routine and Sleep Deprived EEG

A routine EEG takes approximately 45 minutes to perform. Electrodes will be applied on the patient's head to record the electrical activity of the brain. Video may also be recorded to monitor any clinical seizures. The EEG scientist will ask the patient to do some deep breathing for three minutes, and to watch a flashing light whilst opening and closing their eyes. The patient will be required to be relaxed and still for the test.

A specialised service is provided for patients who have recently had their first suspected seizure. The EEG test is most helpful if performed within 24 hours of the seizure, although there is still value, if this is not feasible, in performing it later.

If the initial EEG is negative, an EEG may be performed after a night of sleep deprivation which can increase the chances of recording an abnormality in the EEG.

Long Term Video EEG Monitoring

Video EEG monitoring (VEM) records both your EEG and behaviour during a seizure. If you are being considered for epilepsy surgery the doctors need to know exactly what type of seizures you are having and where in your brain the seizures start. It is also sometimes difficult to distinguish seizures from some other types of events and VEM can help sort this out.

VEM is done while you are a patient at the hospital. At the start of your stay the EEG technicians will apply EEG electrodes to your head and you will be constantly connected to an EEG monitor and videotaped for your whole stay. The average stay is eight days but may last 12 days. For children, admission is usually from Monday to Friday. All patients require a sitter (family  member or friend to identify seizures) to stay with them throughout the inpatient admission. The room is set up with a video camera and computer that record information about attacks and brain function. The cameras are linked to monitors outside the room that are watched during the day by nursing staff. This is to ensure we receive all available information.

During the monitoring you need to stay in the room at all times except for going to the toilet; the room has an ensuite. This means you need to bring enough with you to keep yourself occupied during your stay. For more information about what you can and cannot do during the monitoring please read the Patient Information Brochure. For more information about EEG and VEM procedure please read Austin Health's EEG patient information and VEM patient information documents.



 

MRI (Magnetic Resonance Imaging)

An MRI scan produces pictures of the brain’s structure. It is used to identify any abnormalities in the brain that may be causing the seizures. The MRI machine uses magnetic fields to produce the images. There are no x-rays or radiation involved. Because the machine uses magnets to take the pictures it is important to tell the radiology staff if you have any metal implants.

MRI scans take about one hour to complete. During this time you need to lie still on your back. You will lie on a narrow bed which moves into a tunnel in the scanner. Some people find this a bit unpleasant as there is not a lot of room, but the machine is well lit and ventilated and you will be given music to listen to.

We are constantly trying to gain more information from MRI. You may be asked to have a scan at the Brain Research Institute which has a more powerful instrument than that used routinely.

More information about MRI can be found at the Brain Research Institute website or the Royal Children's Hospital Epilepsy Program site.

 

Figure 2. Preparation of participant for MRI scan

Figure 3. Radiographer monitors participant in MRI Scanner at BRI

 

SPECT and PET

Figure 4. PET Image

SPECT (Single photon emission computed tomography) and PET (Positron emission tomography) scans provide information about the function of your brain.  They use very low levels of radioactivity.
SPECT scans measure blood flow in the brain. This is done by injecting a compound (ECD) into a vein.  Blood flow increases at the time of a seizure so we compare scans performed during a seizure with scans performed when seizures are not occurring. The patient is injected as early as possible after the seizure begins. This is one reason that it is necessary to have a sitter/parent with the patient to identify the seizure as soon as it begins. The ECD localizes in the brain within 30 seconds to give a picture of the blood flow to the brain at that point in time. The scan itself can be taken up to 2 hours after the injection and scanning occurs in the nuclear medicine department. ECD can only be injected between the hours of 8 am and 4.30 pm, as the scanner is closed out of hours.

PET scans use an injection of radioactive glucose (sugar) to show how your brain is using glucose. Often the area in the brain causing seizures may use less sugar inbetween seizures. This scan is usually performed if you have not had a seizure for 24 hours. You are required not to eat or drink for 4 hours prior to the test.

More information about SPECT and PET can be found at the Austin Health Nuclear Medicine web site and the Positron Emission Tomography page of the Royal Children’s Hospital Children’s Epilepsy Program site.

 

Neuropsychology

There are two aspects of the neuropsychology assessment. The first assesses your memory, concentration, language and other thinking functions. This provides us with important information that can assist in the assessment and treatment of your seizures. If appropriate, the second phase involves a detailed assessment of issues related to surgery. Should you have surgery, you will be followed up and reassessed to see whether there are any alterations in functioning.

 

Epilepsy Surgery

The Austin has a well established epilepsy surgery program. Surgery is helpful for a minority of patients with epilepsy who have not responded to antiepileptic medication. We have been performing epilepsy surgery for 30 years with over 500 patients benefiting from the program. Patients admitted under the Comprehensive Epilepsy Program are considered for their suitability for epilepsy surgery. This includes all the tests above and a detailed multidisciplinary evaluation regarding suitability for surgery and the risks and benefits of epilepsy surgery for each person.

In addition to the medical tests, we have a wide ranging pre- and post-operative support program for patients undergoing surgery. This involves a detailed assessment of you and your family to assess psychological and social issues related to surgery. It is important to know how you and your family are feeling about surgery. Careful management of psychological illnesses such as co-existent depression or anxiety is also provided. In order to make a decision regarding epilepsy surgery, you will be counseled about the likely outcome with regard to seizure control, the likely effects on your everyday life and the risks, so that you will be able to make an informed decision.

Our program has been internationally recognised, and provides a range of multidisciplinary services. These include specialist medical and neuropsychological reviews, and psychosocial counselling which are routinely provided at regular intervals after surgery. This is complemented by post-operative phone follow-up by specialist staff.

The Comprehensive Epilepsy Program has established a wide-ranging pre- and post-operative support program for patients who are considered for surgery. More information on the seizure surgery follow-up program.

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Created: 15 Sept 2003
Last modified: 1 Feb 2012
Authorised by: Prof Sam Berkovic
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Maintained by: Susannah Bellows
Email: epilepsy-austin@unimelb.edu.au
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