The electroencephalogram (EEG) is a diagnostic test that records the electrical activity of the brain, being used to identify neurological changes, as in the case of seizures or episodes of altered consciousness, for example.
Usually, it is done by attaching small metal plates to the scalp, called electrodes, which are connected to a computer that records the electrical waves, which is a test widely used because it does not cause pain and can be performed by people any age.
The electroencephalogram can be done either while awake, that is, with the person awake, or during sleep, depending on when the seizures appear or the problem being studied, and it may also be necessary to practice maneuvers to activate brain activity. such as breathing exercises or putting a pulsating light in front of the patient.
This type of exam can be performed free of charge by SUS, as long as it has a medical indication, but it is also performed in private exam clinics, with a price that can vary between 100 and 700 reais, depending on the type of encephalogram and the location that take the exam.
What is it for
The electroencephalogram is usually requested by a neurologist and usually serves to identify or diagnose neurological changes, such as:
- Epilepsy; Suspected changes in brain activity; Cases of altered consciousness, such as fainting or coma, for example; Detection of brain inflammation or intoxications; Complement of the evaluation of patients with brain diseases, such as dementia, or psychiatric diseases; Observe and monitor the treatment of epilepsy; Assessment of brain death. Understand when it happens and how to detect brain death.
Anyone can perform an electroencephalogram, with no absolute contraindications, however, it is recommended that it be avoided in people with skin lesions on the scalp or pediculosis (lice).
Main types and how it is done
The common electroencephalogram is made with the implant and the fixation of electrodes, with a conductive gel, in areas of the scalp, so that the brain activities are captured and recorded through a computer. During the examination, the doctor may indicate that maneuvers are performed to activate brain activity and increase the sensitivity of the examination, such as hyperventilating, with rapid breathing, or placing a pulsating light in front of the patient.
In addition, the exam can be done in different ways, such as:
- Wake-up electroencephalogram: it is the most common type of examination, done with the patient awake, very useful to identify most changes; Electroencephalogram in sleep: it is performed during the person's sleep, who spends the night in the hospital, facilitating the detection of brain changes that may arise during sleep, in cases of sleep apnea, for example; Electroencephalogram with brain mapping: it is an improvement of the exam, in which the brain activity captured by the electrodes is transmitted to a computer, which creates a map capable of making it possible to identify the regions of the brain that are currently active.
To identify and diagnose diseases, the doctor may use imaging tests, such as MRI or tomography, which are more sensitive to detect changes such as nodules, tumors or bleeding, for example. Understand better what the indications are and how computed tomography and magnetic resonance imaging are performed.
How to prepare for the encephalogram
To prepare for the encephalogram and improve its effectiveness in detecting changes, it is necessary to avoid drugs that alter the functioning of the brain, such as sedatives, antiepileptics or antidepressants, 1 to 2 days before the exam or according to the doctor's recommendation, no consume caffeinated drinks, such as coffee, tea or chocolate, 12 hours before the exam, in addition to avoid using oils, creams or sprays on the hair on the day of the exam.
In addition, if the electroencephalogram is done during sleep, the doctor may ask the patient to sleep at least 4 to 5 hours the night before to facilitate deep sleep during the exam.
