Eeg Vs Fmri Fnirs Fus And Pet
EEG has several strong points as a tool for exploring brain activity. EEGs can detect changes over milliseconds, which is excellent considering an action potential takes approximately 0.5â130 milliseconds to propagate across a single neuron, depending on the type of neuron. Other methods of looking at brain activity, such as PET, fMRI or fUS have time resolution between seconds and minutes. EEG measures the brain’s electrical activity directly, while other methods record changes in blood flow or metabolic activity , which are indirect markers of brain electrical activity.
EEG can be used simultaneously with fMRI or fUS so that high-temporal-resolution data can be recorded at the same time as high-spatial-resolution data, however, since the data derived from each occurs over a different time course, the data sets do not necessarily represent exactly the same brain activity. There are technical difficulties associated with combining EEG and fMRI including the need to remove the MRI gradient artifact present during MRI acquisition. Furthermore, currents can be induced in moving EEG electrode wires due to the magnetic field of the MRI.
EEG can be used simultaneously with NIRS or fUS without major technical difficulties. There is no influence of these modalities on each other and a combined measurement can give useful information about electrical activity as well as hemodynamics at medium spatial resolution.
What To Expect During An Eeg
An EEG measures the electrical impulses in your brain by using several electrodes attached to your scalp. An electrode is a conductor through which an electric current enters or leaves. The electrodes transfer information from your brain to a machine that measures and records the data.
Specialized technicians administer EEGs at hospitals, doctors offices, and laboratories. The test usually takes to complete and involves the following steps:
During the test, very little electricity passes between the electrodes and your skin, so youll feel very little to no discomfort.
Will I Have To Have More Than One Eeg Test
There are several ways an EEG test can be done. And there are several reasons why you might be asked to have further EEGs.
- If you have an EEG test that doesnt show any unusual electrical activity in your brain, your doctor might ask you to have another
- It can be helpful, if possible, to have an EEG test at times when you are more likely to have a seizure. For example, this might be early in the morning. For some women, it might be around the time of having a period
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How Should I Prepare For The Test
- Make sure your hair is clean, freshly washed, and free from any styling products. If you have long hair, do not braid, tie, or pin it up.
- You may eat regular meals, but avoid drinks that contain caffeine for at least 4 hours before the test.
- Do not nap before the test.
- Continue taking your medicine unless your doctor tells you to stop.
What Does It All Mean
So EEGs show what is happening in the brain during the test, but why is this helpful in epilepsy? Epileptic seizures are caused by disturbed brain activity which simply means that the normal activity of the brain is suddenly interrupted and changes. When a seizure happens during an EEG, the normal pattern of brain activity that is seen on the EEG reading changes, and different brain activity can be seen.
In focal seizures the change in brain activity can be seen only on the electrodes on the part of the brain the seizure is happening in. The readings from the rest of the electrodes remain the same as normal brain activity . In generalised seizures the altered activity can be picked up by all the electrodes, from all parts of the brain.
Focal seizures . These are seizures that happen in, and affect, only part of the brain and start from a ‘focal point’ in the brain. What happens in these seizures varies depending on which part of the brain is affected and what that part of the brain normally does.
Generalised seizures seizures that happen in, and affect, both sides of the brain from the start. There are many different types of generalised seizures but they all involve the person becoming unconscious, even just for a few seconds, and they won’t remember the seizure itself. The most well-known generalised seizure is the tonic clonic seizure.
What Does An Eeg Test Involve
During the EEG, flat metal discs will be placed all over your scalp. They are usually kept in place with a sticky paste. You wont need to cut your hair.
These discs are also attached to wires that send the electrical signals to a computer to record the brain waves. You wont feel any sensations from the discs.
You will need to keep still during the test. You may be asked to do some deep breathing, look at a flashing light or sleep during the test.
An EEG takes about an hour, but may be longer for a sleep recording. Sometimes EEGs are conducted when you have purposely been sleep-deprived.
How Long Will It Take To Get My Eeg Results
You will not normally get your EEG test results on the same day. This is because the recordings will need to by studied by the specialist first and then sent to the doctor who requested the tests. It will usually be a few days or weeks before they can discuss your results with you.
If you have any other questions about an EEG test, you could ask your family doctor, epilepsy specialist, epilepsy specialist nurse or the person who will carry out the test.
If you would like to see this information with references, visit the Advice and Information references section of our website. If you are unable to access the internet, please contact our Epilepsy Action Helpline freephone on 0808 800 5050.
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What Is Eeg And How Does It Work
Bryn Farnsworth, Ph.D
Your brain runs the show. Think of the last time you tried to solve a crossword puzzle or started to learn a new language. Recall the last time you woke up in the middle of a weird dream or needed to find your way in a city you have never been before.
As you think, dream, see, and sense, your brain is constantly active, absorbing all information, compacting and re-connecting existing data, and integrating everything into a consistent experience. For you, that experience constitutes your reality.
Your brain is alive. Your brain shapes how you see your environment, filters or highlights objects and information most relevant to you. It creates its own stories based on your thoughts, emotions, desires and experiences, ultimately driving your behavior.
In this article you will get a basic overview of EEG and how it works:
What Are The Different Types Of Eeg
There are several types of EEG. Some of the most common are:
These last 30 minutes to one hour. You might be asked to breathe deeply, look at a flashing light or open and close your eyes.
The electrical activity in our brains is different when we are asleep or awake. In a sleep-deprived EEG you will be asked to not sleep the night before the test so you are more likely to fall asleep during the day. This means the neuropsychologist can look at your brainâs electrical patterns when you are sleeping.
A routine EEG might be too short to diagnose epilepsy. In an ambulatory EEG, you wear a kind of EEG hat for a few hours or days at a time. This makes it more likely that the EEG will record when you are actually having a seizure.
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You Can Go With Your Child Into The Recording Room
As a parent/guardian/caregiver, you will be able to go with your child into the recording room. You will be able to help the technologist get your child’s full cooperation. It is best that no more than 2 adults are with your child. Generally, it is best if other children do not come as they can distract your child having the test.
Your baby or toddler will be able to sit on your lap and you can feed them. If your child is older, the technician will ask them to lie on a bed.
How Can Technicians Get The Most Information From An Eeg
The EEG records brain waves for 20 to 45 minutes, which is only a small amount of time. Abnormalities do not occur all the time but technicians can do things to increase the chances of picking up abnormalities during the recording time. These include:
- sleep deprivation
- flashing lights
- opening and closing eyes
Technicians usually video your child during the EEG. This helps the specialist interpret the EEG. Once the specialist has finished the EEG report, they will usually delete the videos unless the video has recorded an event of interest.
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The Technician Will Attach About 24 Small Silver Discs To Your Child’s Head
The technician will measure your child’s head. They will then mark the electrode positions with a special crayon. The technician will attach about 24 small silver discs to your child’s head using either paste or tape. They place the discs in various positions on your child’s head, forehead and earlobes. They will also put one disc on one or both shoulders to record your child’s heart. Some EEG departments use a rubber cap or some gel to keep the electrodes in place.
It will take about 15 – 20 minutes to put the electrodes on. It is very important that your child stays fairly still during the whole process, as well as during the recording.
You can read to your child while the technician puts the electrodes on, and during the recording.
When An Eeg Is Used
An EEG can be used to help diagnose and monitor a number of conditions affecting the brain.
It may help identify the cause of certain symptoms such as seizures or memory problems or find out more about a condition you’ve already been diagnosed with.
The main use of an EEG is to detect and investigate epilepsy, a condition that causes repeated seizures. An EEG will help your doctor identify the type of epilepsy you have, what may be triggering your seizures and how best to treat you.
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How Do I Get Ready For An Eeg
Your healthcare provider will explain the procedure to you, and you can ask questions. Ask your provider what you should do before your test. Below is a list of common steps that you may be asked to do:
You’ll be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if something isn’t clear.
Wash your hair with shampoo, but don’t use a conditioner the night before the test. Don’t use any hair styling products, such as hairspray or gel.
Tell your provider about all prescription and over-the-counter medicines and any herbal supplements that you’re taking.
Stop taking medicines that may interfere with the test if your provider has told you to do so. Don’t stop using medicines without first talking your provider.
Don’t consume any food or drinks containing caffeine for 8 to 12 hours before the test.
Follow any directions your provider gives you about reducing your sleep the night before the test. Some EEG tests require that you sleep through the procedure, and some don’t. If the EEG is to be done during sleep, adults may not be allowed to sleep more than 4 or 5 hours the night before the test. Children may not be allowed to sleep for more than 5 to 7 hours the night before.
Don’t fast the night before or the day of the procedure. Low blood sugar may influence the results.
Based on your health condition, your provider may request other specific preparations.
Will I Have To Give My Consent For An Eeg Test To Be Done
You will usually have to give your consent to having an EEG test done. This is because it is important that you are aware of why the test is done and of its risks, however small they might be. A video recording is usually recorded as part of the EEG test. Your consent will also be needed for this.
If you give your consent, but then change your mind, you can withdraw your consent at any time. The NICE guidelines say you should be given information on the reasons for tests, their results and meaning, the reasons for of specific investigations, and how they will be carried out.
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What Can An Eeg Find That An Mri Cant Find
Your brain works in wonderful and mysterious ways allowing you to walk, talk, and do everything that a human can do. Thats why we take so much care to protect our heads from injury.
But, what happens when the brain doesnt work the way its supposed to? The United Nations reported that about 1 in 6 people on earth today have some kind of neurological disorder!
Sometimes, doctors can intervene and remedy some of these brain disorders. But, they have to get a good look at your brain and how it works. Keep reading to learn the difference between an EEG and an MRI and how they help doctors understand your brain better.
What To Expect During An Eeg Test
Setup: An EEG technologist will measure your child’s head and mark the electrode locations. This will take about 30 minutes. The tech will scrub your child’s scalp to remove any oil or dead skin and then apply a paste that helps the electrodes stick to the scalp.
Hyperventilation: Your child may be asked to breathe rapidly and deeply for a few minutes. This may cause mild dizziness or tingling, but those sensations will pass quickly when he or she returns to normal breathing.
Photic stimulation: A flashing light may be placed in front of your child’s closed eyes. This often causes visualization of various colors and patterns.
The technologist will monitor the computer for accuracy and make necessary adjustments. If your child is old enough, the technologist may ask him or her to follow instructions, such as opening and closing his or her eyes or looking at a flashing light.
The more relaxed your child is, the more accurate the results will be. If your child is old enough to understand, talk about the importance of staying quiet and still during the 20- to 45-minute test.
An EEG is painless, and your child can resume normal activities afterward.
Your child’s hair will be a bit messy after the test. The tech will remove most of the paste, but you should plan to wash your child’s hair again when you get home.
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Are There Any Risks
The EEG has been used for many years and is considered a safe procedure. The test causes no discomfort.
The electrodes simply record activity. They do not produce any sensation. In addition, there is no risk of getting an electric shock.
In rare instances, an EEG can cause seizures in a person with a seizure disorder due to the flashing lights or the deep breathing that may be involved during the test. If you do get a seizure, your healthcare provider will treat it immediately.
Please alert your physician if you have a seizure disorder. Other risks may be present, depending on your specific medical condition. Be sure to talk about any concerns with your healthcare provider before the procedure.
Immediately After The Eeg
Once the test is complete, the electrodes are removed and you are allowed to get up. The results need to be analysed at a later stage by a neurologist .Generally, if there is no abnormality to the brain’s electrical activity, the pattern of ‘peaks and valleys’ charted by the EEG should be fairly regular. If excited, the pattern will show considerable variation, and any departure from the regular pattern can indicate abnormalities.
Note About Sleep Electromyography Or Electroencephalogram Clinic Appointments During The Covid
At this time, all non-essential out-patient appointments are cancelled, and we are reaching out to patients by phone or email to let them know.
- If you are an EMG patient and have questions, you can call 416-480-4475.
- If you are an EEG/Evoked Potentials patient and have concerns, kindly contact your referring office directly.
- If you are a patient in the sleep clinic with concerns about an upcoming appointment, please reach out to your sleep doctors office.
All in-patient EEGs and EMGs are still being completed.
How To Prepare For The Test
Wash your hair the night before the test. DO NOT use conditioner, oils, sprays, or gel on your hair. If you have a hair weave, ask your health care provider for special instructions.
Your provider may want you to stop taking certain medicines before the test. DO NOT change or stop taking any medicines without first talking to your provider. Bring a list of your medicines with you.
Avoid all food and drinks containing caffeine for 8 hours before the test.
You may need to sleep during the test. If so, you may be asked to reduce your sleep time the night before. If you are asked to sleep as little as possible before the test, DO NOT eat or drink any caffeine, energy drinks, or other products that help you stay awake.
Follow any other specific instructions you are given.
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