The electroencephalogram (EEG) is a test that measures and records electrical activity in the brain. Presentation with Dr. Marc Rey, neurologist specializing in sleep, president of the National Institute of Sleep and Vigilance (INSV).
Definition: what is an EEG?
The EEG or electroencephalogram is a test that records brain activity. This is transcribed in the form of traced from electrodes placed on the scalp. The EEG is absolutely painless. The electroencephalogram is mainly performed in cases of suspected epilepsy, sleeping troublesof a number of neurological diseases. Two flat EEGs 4 hours apart signify brain death, in the absence ofhypothermia or sedative drugs.
What are the indications for an EEG?
The main indications of the EEG are:
- The diagnosis and follow-up of epilepsy
- The sleeping troubles
- The balance sheet of repeated discomfort
- All forms of brain pain (confusional states, comainfectious diseases, etc.) inducing a dysfunction in the electrical activity of the brain.
The subject is installed in a quiet place, on an armchair. 21 electrodes are placed on the scalp, cleaned using a conductive paste, and maintained using a helmet. They are connected to a monitor and a printer. Cerebral activity is transcribed in the form of tracings. These plots are analyzed by a neurologist which can determine if they reveal a neurological abnormality. He can be performed while sleeping or in the context of an activity, depending on the pathology sought. “The recording lasts about twenty minutes. during which activation maneuvers will be performed to vary cerebral electrical activity. In particular, the patient will be asked to hyperpnea, that is to say to breathe very hard for three minutes to observe the impact this has on the electrical activity of the brain. It is also offered a intermittent light stimulation which will deliver light flashes of variable frequency. As part of the diagnosis of epilepsy, a longer recording over the day and night may be necessary. In this case, the electrodes will be connected to a box that you carry with you“, specifies Dr. Marc Rey. In other words, the EEG is a varied recording technique depending on what you are looking for: measure the sleeprecord an epileptic seizure and determine whether brain electrical activity is normal or abnormal.
“No specific preparation is necessary for the EEG. Sometimes, the patient whose sleep we are going to explore as an epilepsy activator is asked to sleep deprivation, i.e. go to bed late and get up early“, indicates the neurologist specializing in sleep.
The EEG is practiced less and less since there are scanners and MRIs.
“It is very complicated to interpret an EEG. It is the neurologist’s work than reading brainwaves. The EEG is practiced less and less since there is the scanner and MRI“, informs the specialist.
What is a normal or abnormal EEG?
“The normality of the EEG depends on the clinical situation: age, state of alertness, activity of the subject (e.g. changes in the EEG induced by hyperpnea may be normal or abnormal depending on the age of the subjects), the treatment taken, this is what makes the analysis of the EEG difficult, which requires long training“, indicates the neurologist specializing in sleep.
What is the cost of an EEG and is it reimbursed?
The price of an EEG varies between 130 and 150€. The exam is reimbursed by social security and can be covered by a complementary mutual.
Thanks to Dr. Marc Rey, sleep neurologist, president of the National Institute of Sleep and Vigilance (INSV)