What is an EEG

What is an EEG (electroencephalography) test?

An electroencephalogram (EEG) is a test that measures brain activity - an extremely important diagnostic tool used in medicine. During this painless assessment, small sensor-electrodes are attached to the scalp to pick up the electrical signals produced by the brain. The brain cells communicate by means of electrical impulses and are active at all times, even during sleep. This activity appears as waves on the EEG recording. Brain waves (synchronised electrical impulses) reflect communication between areas of the brain. Brain waves can reveal information about physiological state and cognitive functioning, including stress levels or attention. These signals are recorded by a machine and analysed by a specialist. The EEG is one of the main diagnostic tests for epilepsy. It also plays a role in the diagnosis of many other disorders.

Indications for an EEG: why is an eeg test done?

An EEG test can help to diagnose and monitor a range of neurological conditions. It is used to identify the cause of some symptoms - such as memory problems - or to find out more about a condition that has already been diagnosed. An EEG test can help your physician to determine the type of epilepsy you suffer from, what may cause epileptic seizures and how most effectively to treat you. An EEG test helps doctors to assess disorders of consciousness. It can also be used additionally in the diagnosis of psychiatric and other neurological disorders.

EEG is also used in disorders such as:

• dementia
• head injury and concussion
• brain tumours
• encephalitis
• sleep disorders such as sleep apnoea.

EEG testing in children

EEG testing can also be performed in children. EEG tests are usually performed when children show developmental delays or symptoms such as loss of consciousness, headaches. The EEG will help to determine whether epileptic seizures or other neurological disorders are the cause of the symptoms.

The EEG procedure: What the EEG test looks like?

During an EEG test, the patient sits or lies down and electrodes are placed on the scalp using a special gel. The patient is asked to relax or perform specific tasks (e.g. closing and opening the eyes, deep breathing) while data are recorded on a computer for a set period of time.

Below we have described in detail how the EEG testing routine is carried out:

• You will be asked to relax in a chair or lie down on a bed.
• Electrodes will be attached to your scalp using a special paste, or a cap containing electrodes to which conductive gel is applied will be used.
• You will be asked to close your eyes, relax.
• Once the recording has started, you will be asked to remain relatively still throughout the test. You may be monitored by the technician performing the test to watch for movements that may cause possible interference with the recording, such as swallowing or blinking. The examination can be paused to allow you to rest or change position, if necessary.
• After the initial recording has been made, the specialist may test you with various stimuli. For example, you may be asked to breathe deeply and quickly for 3 minutes or you may be exposed to a bright flashing light.
• If you are being assessed for a sleep disorder, the EEG should be performed while you are asleep.

What happens after an EEG test is performed?

After the end of the EEG test, the electrodes will be removed and the paste/gel will be washed off with warm water. In some cases it may be necessary to wash the hair again at home. There may be a slight redness of the skin at the electrode sites, but this will subside within a few hours.

You will usually receive the results within 3-4 days). The EEG signal will first need to be analysed by a specialist. Our specialist can give you additional instructions after the procedure, depending on your specific situation.

EEG recording: What does a typical EEG recording look like?

Typical EEG recording is characterised by regular and symmetrical brain wave patterns. Brain waves have their own specific parameters, such as frequency and amplitude, which are taken into account when interpreting the results. These parameters, in combination with other information such as the patient's age, alertness or sleep state and location of the electrode on the scalp, are interpreted by the specialist.

The most widely known classification uses the frequency of EEG waves (alpha, beta, theta and delta)

Alpha waves - 8-13 Hz

Alpha waves occur rhythmically on both sides of the head, but often have a slightly greater amplitude on the right side, especially in right-handed people. It is a dominant rhythm in the central and occipital regions (at the back of the head), particularly prominent with eyes closed and in a relaxed state. Alpha activity tends to disappear with attention (e.g. calculations in memory, stress, or opening the eyes).

Beta waves - over 13 Hz

Beta waves tend to be small in amplitude, are usually symmetrical and more prominent at the front. Drugs such as barbiturates and benzodiazepines can increase beta waves.

Theta waves - 3.5-7.5 Hz

Theta and delta waves are collectively known as slow waves, which have a greater amplitude than faster (higher frequency) waves. Theta waves usually occur during sleep regardless of age. In conscious adults, these waves are abnormal when present in excess.

Delta waves - 3 Hz or below

Usually observed during deep sleep in adults, as well as in infants and children.

Delta waves are abnormal in a conscious adult. Delta waves can be focal (localised pathology) or diffuse (generalised dysfunction).

Other parameters assessed in the EEG recording are the morphology (i.e. shape) of the brain waves

Spiking, sharp waves may be indicative of pathology, e.g. epilepsy.

Interpretation of electroencephalography results

The interpretation of the EEG results is made by a specialist who analyses the brain wave patterns and can determine the presence of abnormalities in the electrical activity of the brain. Based on these results, the clinician can make a diagnosis and recommend appropriate treatment. Clinical symptoms combined with the interpretation of the EEG results are important in making an appropriate diagnosis.

What is the QEEG?

QEEG (Quantitative Electroencephalography) or more commonly known as Brain Mapping is an advanced electroencephalography analysis technique that allows to measure and analyse the electrical activity of the brain in more detail than a traditional EEG test. Using QEEG, a brain map is created to quantify the power, quantity, distribution and ratio of different brain waves.

What is the difference between EEG and QEEG?

A standard electroencephalographic evaluation is based on the observation of brain wave patterns, which allows a general assessment of the state of brain activity. The specialist describing the recording analyses the basic features of the EEG signal and is thus able to detect possible abnormalities, such as those indicative of epilepsy or other disorders mentioned above.

QEEG, however, goes one step further, enabling a detailed analysis of the frequency, amplitude and patterns of brain waves in different brain areas. For QEEG analysis, the computational power is used rather than visual analysis alone. This allows more precise information to be obtained about the patient's brain function, such as dysfunctions in specific brain areas or imbalances between different types of brain waves

What does the QEEG study detect?

QEEG is a very valuable element of the comprehensive assessment at the Magwise clinic. It helps to understand the electrical activity of the brain. It can show whether brain activity is too high or too low at certain frequencies for a particular condition.

QEEG testing can be helpful:

• As an additional diagnostic tool in identifying cognitive and psychiatric conditions
• In predicting response to medication, for example the likely response to antidepressants
• In providing valuable information in developing a personalised treatment plan and in tracking their progress.
• In providing objective information used to create a personalised EEG Biofeedback treatment programme or to determine a treatment protocol for transcranial magnetic stimulation (TMS).

We can use the QEEG information as a guide to determine the most effective solutions to help you improve your memory, increase your concentration and attention, minimise anxiety, or increase the effectiveness of treatment for various neuropsychiatric conditions, including depression.

QEEG plays a key role in the diagnostic process as well as in the choice and monitoring of treatment. With precise analysis, clinicians can more accurately understand a patient's brain activity and adapt treatment based on this information. This is particularly important as it enables a personalised therapeutic approach, tailored to the needs of the individual patient.

QEEG allows the personalisation of EEG Biofeedback and TMS therapy

QEEG is used in the selection of the EEG Biofeedback therapy protocol, as well as in the personalisation of transcranial magnetic brain stimulation (TMS) therapy. When chosing particular treatment based on the QEEG result, we can increase the effectiveness of the therapy. At Magwise, we specialise in TMS therapy and provide the best possible solutions by combining TMS stimulation with QEEG testing. We always support the EEG Biofeedback therapy protocol with the results of a mini QEEG or a full QEEG.

QEEG allows the monitoring of treatment effects

The image shows the effects of ADHD treatment. The change before and after EEG Biofeedback therapy can be seen here: in the form of a decrease in beta wave power. The high beta wave in the back is corresponding to excitation and lack of attention.

To find out more, we invite you to contact the Magwise Clinic, where we perform and interpret both EEG and QEEG. In our practice, we use these analyses to diagnose, plan and monitor therapy, in order to enhance and optimise the treatment process.