The Role of EEG in the Diagnosis of Epileptic Syndromes

The Electroencephalogram EEG, or as it is commonly referred to in everyday language (the "Ezhe"), is an examination used to detect the brain's electrical activity through a system of electrodes, which transmit signals they receive from the scalp to a computerized system. This signal is analyzed and converted into a wave system through which various brain-related issues are diagnosed. Brain cells continuously communicate with each other through the exchange of electrical impulses between them.

EEG is an auxiliary tool in the diagnosis of epileptic syndromes, brain tumors, head traumas, encephalitis, stroke, sleep disorders, and confirming brain death in comatose patients. It is a free, safe, and non-invasive examination.

A bit of history. In 1875, Richard Caton presented his findings in the British Medical Journal. Through a galvanometer, he confirmed the presence of electrical phenomena in the brains of dogs and monkeys. In 1924, German scientist Hans Berger was the first to perform an EEG on a human. He discovered the alpha rhythm, which was named Berger's rhythm after him.

Almost all parents have a question before conducting an EEG for their child.

Is EEG (Ezhe) harmful?

Answer: Absolutely Not

EEG in pediatric ages has specific characteristics that differ from adults, both in terms of recording technique and data interpretation. The recording technique is extremely important as it determines the quality of the interpretation. The EEG recording technique requires not only experience but primarily a deep theoretical knowledge. An incorrect technique is accompanied by incorrect interpretation, and the consequences can be severely detrimental as the incorrect treatments that result can extend for years. EEG in children in the first months of life changes every month and in the following years changes from year to year. Therefore, a good interpreter must be familiar with the different normal patterns according to age to further judge the abnormal patterns that correspond to different epileptic syndromes, which vary both in terms of therapeutic strategy and prognosis. Therefore, it is advisable to ensure that the person conducting the examination has the necessary training for EEG in pediatric ages before conducting an EEG for your child.

Before starting the EEG recording, we need to have a strategy. We need to know which epileptic syndromes to differentiate and based on this, we will choose the way of conducting the EEG, awake or asleep, activation tests such as opening and closing eyes, hyperpnea, and photostimulation, the type of electrodes to be used, their number, the way they will be positioned, etc.

The use of different montages during the examination is a very important moment. This is why an examination is better viewed directly on the computer in the original software, which allows manipulation of all the elements contained in the program, rather than a simple EEG printed on paper. The examiner must be not only a good EEG interpreter but also have very good skills in using computer programs.

The quality of the electrodes and the type of gel used directly affect the impedance between the electrode and the skin, and consequently, the signal quality.

Electrodes can be coated with gold, silver, platinum, etc. Each of them has its own characteristics regarding the signal it transmits and obviously, they have different costs. The way they are positioned is important. It cannot be done empirically but must be based on protocols defined by the International Society of Neurophysiology. As a result, mistakes produce some waves that are called artifacts and can be mistakenly interpreted as paroxysmal waves.

Artifacts are produced for various reasons such as improper positioning of the electrodes, poor impedance with the skin, poor quality of the electrodes and the gel, but can also be due to muscle activity or EKG in the area of electrode placement as well as artifacts from movements. Children move a lot during the examination, so this is one of the reasons why EEG in children under the age of 3 ½ years must be performed compulsorily in sleep. Another reason for this is because in sleep, anomalies that are hidden if the EEG is performed awake are revealed. Therefore, never accept that children of this age be examined awake. Always insist that the examination be performed in sleep. The use of benzodiazepines to put the child to sleep during the examination is unacceptable as the EEG results will not be real.

Often we see that protocols are not followed, and examinations are conducted by people who have practical experience but lack theoretical knowledge.

The role of EEG in the diagnosis of epileptic syndromes is undeniable. Primarily, it is important in differentiating epileptic seizures from pseudo-seizures. Different epileptic syndromes have different electroencephalographic patterns such as Ohtahara Syndrome with burst suppression, West Syndrome with hypsarrhythmia, Absence with 3 Hz generalized paroxysmal discharges, rolandic epilepsy with centrotemporal paroxysmal anomalies, and many other syndromes with specific clinical and electroencephalographic characteristics.

Long-term EEG monitoring, which means monitoring throughout the night, is very important today. This is a very important examination method for patients who have convulsive seizures but have normal results in the performed EEG.

EEG is an examination that is repeated as often as required by the specialist doctor. EEG is done before starting treatment, during the follow-up of treatment at every step to monitor the treatment results, and of course, plays an important role before deciding to discontinue the treatment.