**4.1 Photostimulation**

Photostimulation is carried out using a special device combined with an electroencephalograph, which makes it possible to produce rhythmic light flashes at a given frequency.

The color of the flash may be white or red, depending on the design of the device. The light source can be a gas discharge lamp or high-power LEDs. *Practical Recommendations for Conducting an EEG Study in a Neurophysiological Laboratory DOI: http://dx.doi.org/10.5772/intechopen.108879*

#### **4.2 Contraindications for the test**

Pregnancy is a relative contraindication to a photostimulation test, as there is a risk of adverse effects on the fetus in the event of an epileptic seizure.

**Important!**

**When using a photostimulator with a gas discharge lamp as a light source, never test with open eyes, due to the risk of eye damage from the powerful light flux of the gas discharge lamp!!!**

#### **4.3 Hyperventilation**

During hyperventilation, the subject takes a deep breath (trying to fill the lungs as best as possible and exhale through slightly closed lips).

#### **4.4 Contraindications for the test**

Relative contraindications to the hyperventilation test: History of indications of cardiac arrhythmias Intracranial tumors of subtentorial localization Myocardial infarction Diabetes mellitus in the stage of decompensation Acute intoxications Chronic obstructive pulmonary disease Frequent series of generalized and secondary generalized seizures

#### **4.5 Absolute contraindications**

Trauma to the upper respiratory tract Paroxysmal ventricular arrhythmias Acute period of myocardial infarction Pneumothorax

In addition to the contraindications listed above, the hyperventilation test should not be continued if true epileptiform activity is clearly presented in the record, since the main goal of the test has been achieved, and its continuation may lead to the development of a clinical seizure, or in an unfavorable case, status epilepticus.

#### **Important!**

When performing the test, frequent, shallow, and ineffective breathing should be avoided, since in this case, the state of hyperoxia is not achieved and the test becomes ineffective.

#### **Important!**

The main task of a routine examination is to ESTABLISH A DIRECT RELATION-SHIP between the development of a functional disorder and the type of functional load imposed, which is confirmed by the development of pathological activity in the EEG recording!!!

In the absence of a direct connection between the development of a functional disorder and a provoking factor, it is concluded that further examination is necessary using long-term EEG recording technologies.
