RU2462987C1 - Method of detecting epileptiform activity - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to neurology and psychiatry. Electroencephalogram (EEG) is registered at the background of hyperventilation on orthostatic table first in horizontal position, then, after turning the table on 60-70 degrees and bringing the examined person in orthostatic position. Registration of EEG is carried out in patient within 1 hour after sleepless night. Turning of orthostatic table is performed during 3-5 seconds. Examined person is brought into orthostatic position for 10 minutes and hyperventilation in orthostatic position is performed for 3 minutes. If signs of orthostatic blood circulation disorder are absent and epileptoform patterns are present, epileptoform activity is diagnosed.

EFFECT: method extends arsenal of means for detection of epileptiform activity.

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Description

The invention relates to medicine, namely to neurology and psychiatry, and can be used to detect epileptiform activity.

A known method for detecting paroxysmal activity by deprivation of sleep for one night [1]. The mechanism of action is associated with the fact that sleep deprivation leads to increased synchronization on the EEG, and this, as already mentioned, is a factor conducive to the development of epileptic potentials in the brain.

A known method for detecting paroxysmal activity on the EEG by conducting 3-minute hyperventilation, while there is a decrease in blood pCO2, which leads to reflex spasm of arterioles and a decrease in cerebral blood flow, which ultimately leads to cerebral hypoxia [2]. Experimental data show that hypoxia leads to depolarization of the membrane of neurons, an increase in their excitability and a general depolarization shift in the cortex, which is associated with the provocation of pathological activity in epilepsy [3]. Hyperventilation is a generally accepted method of provoking epileptiform activity and is included in the standard set of functional tests. The main disadvantage of this test is its age specificity (the most informative in children under 13 years of age).

A known method for detecting paroxysmal activity on an EEG by recording the electrical activity of the brain for a long time (up to 5-7 days). Long-term recording of EEG in various functional states of the patient significantly increases the likelihood of recording paroxysmal activity [4].

The disadvantages of this method are the high cost of time for medical personnel and the patient.

The closest in technical essence to the proposed one is a method for detecting epileptiform activity, including recording an electroencephalogram (EEG) on an orthostatic table in a semi-vertical position against a background of hyperventilation [5] (RF Patent No. 2409315). The disadvantage of this method is the lack of accuracy and information, due to the fact that the registration of the EEG is carried out only in the state of active wakefulness of the patient and excludes registration in the state of sleep and sleep-wakefulness transitions.

A new technical task is to increase the accuracy and information content of early diagnosis.

To solve the problem in a method for detecting epileptiform activity, which includes recording an electroencephalogram (EEG) on the background of hyperventilation on an orthostatic table, first in a horizontal position, with its continuation, after turning the table 60-70 degrees and transferring the subject to orthostatic position, followed by identification of epileptiform patterns, registration of sleep EEG is carried out in a patient within 1 hour after a sleepless night, and the rotation of the orthostatic table is carried out for 3-5 seconds, traveling to orthostatic position for 10 minutes, in which hyperventilation is carried out for 3 minutes, and in the absence of signs of orthostatic circulatory disorder and the presence of epileptiform patterns, epileptiform activity is diagnosed.

The method is as follows.

To diagnose the subject, a complex functional load is carried out, including a test with falling asleep after a sleepless night, then when awakening, a passive orthostatic load with forced breathing in an orthostatic position is performed. EEG assessment is carried out visually and automatically; epileptiform patterns are detected according to the generally accepted classification [6].

The inventive method differs from the prototype in that for the detection of epileptiform activity, a combined functional load is used, consisting in a combined effect on the metabolism of brain neurons of different functional states of the brain: sleep and wakefulness. In the wakeful state, factors influence: orthostatic load and hyperventilation. The mechanism of the effect of orthostatic load on the electrical activity of the brain has not been studied and can be mediated both by local ones - in the form of circulatory disorders, blood gas composition, and distant factors due to the increasing non-specific activating effects of stem formations on the cerebral cortex.

The method is as follows.

After a sleepless night, the patient falls asleep on an orthostatic table. EEG is recorded in a horizontal position for 1 hour. Then the table is quickly (within 3-5 seconds) rotated by 60 ° -70 ° and the subject is transferred to the semi-vertical position for 10 minutes, in which hyperventilation is performed without stopping the registration of the EEG in the absence of the diagnostically significant orthostatic circulatory disorder in the subject. When processing recordings, epileptiform patterns of EEG regions are distinguished according to the generally accepted classification.

The mode of the method is based on the results of the analysis of clinical observations of 73 patients aged 16 to 69 years (32 men and 41 women, average age 33.8 ± 13.8 and 35.3 ± 13.1 years, respectively) who applied for examination for first-time or rare bouts of loss of consciousness.

In all subjects undergoing routine EEG with standard functional loads, epileptiform patterns were not detected.

When falling asleep after a sleepless night in 13 patients at various stages of sleep, epileptiform EEG patterns were revealed (mean age 28.2 ± 5.5 years).

After transferring the patient to an upright position, 10 patients revealed epileptiform EEG patterns (mean age 26.1 ± 6.5 years). After hyperventilation in the orthostatic position, epileptiform activity was recorded in 14 patients (mean age 27.7 ± 6.2 years). After transferring to the clinostatic position, only one patient retained pathological electroencephalographic rearrangements, which indicates the specificity of the samples used with respect to the recorded electroencephalographic rearrangements.

In the proposed method, load tests are carried out in order of increasing functional load on the brain: sleep - waking up - orthostatic test - hyperventilation. Sleepless night is a factor that disrupts the biorhythmic structure of the sleep-wake cycle and causes a state of dosed stress. If necessary, the appointment of several sleepless nights. This helps to increase the detectability of epileptiform activity.

An orthostatic test is required to identify disorders of the cardiovascular system that can contribute to the occurrence of attacks of loss of consciousness, and their registration is necessary.

The rotation of the table is carried out for 3-5 seconds - the time required to obtain a sharp outflow of blood from the patient’s head. In a short time, mechanisms to compensate for the gravitational impact do not have time to connect, which helps to reduce blood flow.

The duration of each sample is determined as follows.

Time in the amount of one hour is sufficient, including the transition from falling asleep to 1-4 stages of sleep.

Carrying out a passive orthostatic test for 10 minutes is due to the duration of the initial reaction of the brain caused by the redistribution of blood flow when moving to an upright position. This time is enough to reduce cerebral blood flow, without complications in the form of fainting.

The duration of deep breathing for 3 minutes is necessary to obtain a significant change in the balance of oxygen and carbon dioxide in the blood, and at the same time there is no risk of fainting and pre-fainting conditions of the patient during hyperventilation during electroencephalographic studies [1,6].

Clinical examples

Example 1. Patient L., 29 years old, a woman complains of rare fainting during the day and convulsive conditions when waking up.

Standard EEG without features, epileptiform activity is not registered.

A study was carried out according to the proposed method: an EEG with a complex load, including sleep deprivation, a test with falling asleep, a passive orthostatic load revealed epileptiform activity in the form of:

- EEG sleep. Epileptiform EEG activity of falling asleep. Single commissures and sharp waves in outbreaks of polymorphic activity, without accompanying motor phenomena. The location of phenomena in the central parietal region, more to the right.

- EEG background, wakefulness. Epileptiform activity is not registered.

- EEG reactive (passive orthostatic load) while awake. Revealed epileptiform activity in reactive EEG, which was confirmed by the presence of single adhesions and sharp waves in the bursts of polymorphic activity, without accompanying motor phenomena. The location of phenomena in the central parietal region, more to the right.

Example 2. Patient Sh., 26 years old, female complaints of rare fainting in the daytime.

- EEG sleep. Epileptiform activity in a dream is not registered.

- EEG background, wakefulness. Epileptiform activity is not registered.

- EEG reactive (passive orthostatic load) while awake. Epileptiform activity is not registered.

- EEG reactive (passive orthostatic load with hyperventilation). Epileptiform activity was recorded in the form of: multiple commissures and sharp waves in outbreaks of polymorphic activity, without accompanying motor phenomena. The location of phenomena in the posterior temporal region, more to the left.

Thus, the application of the proposed method improves the accuracy of early diagnosis of epileptic activity in patients with rare or first-time attacks. While in the prototype method, epileptiform phenomena were detected in 9.0% of patients after transferring to the semi-vertical position and 15.7% during hyperventilation, when using the proposed method, epileptiform phenomena were detected in 17.8% of patients when falling asleep after a sleepless night, in 13.6% of patients after transfer to the semi-vertical position and in 19.1% after hypeventilation, thus, the detection rate increased by 2 times.

The proposed method has the following advantages: it increases the likelihood of detecting epileptiform activity on the EEG in all age groups, including adults, it is safe because a change in the functional states of the brain in the sleep-wake cycle and passive orthostatic load is used to decompensate cerebral neurodynamics.

Information sources

1. Zenkov L.R., Ronkin M.A. Functional diagnosis of nervous diseases. M., Medicine 1991, 640 p.

2. Drake M.E., Miles E. Paroxysmal hyperventilation responses in the adult Electroencephalogram. // Clin. Electroencephalogr. 1986, v. 17.2, p. 61-65.

3. Okudzhava V.M. The main neurophysiological mechanisms of epileptic activity. Tbilisi: Metzniereba, 1969. P.224.

4. Avakyan G.N., Anisimova A.V., Ayvazyan S.O., Generalov V.O. Video-EEG monitoring in the modern diagnosis and control of the treatment of epilepsy. Manual for doctors. GOU VPO "Russian State Medical University" of Roszdrav. M. 2006.

5. Patent RU No. 2409315, publ. 01/20/11 (prototype).

6. Mukhin K.Yu., Petrukhin A.S., Glukhova L.Yu. Atlas of electro-clinical diagnosis. - M .: Alvarez Publishing, 2004 .-- 440 p.: Ill.

Claims (1)

A method for detecting epileptiform activity, including recording an electroencephalogram (EEG) against a background of hyperventilation on an orthostatic table, first in a horizontal position, then, after turning the table 60-70 ° and transferring the subject to an orthostatic position, followed by identification of epileptiform patterns, characterized in that the registration EEG sleep is carried out in a patient for 1 h after a sleepless night, and the rotation of the orthostatic table is carried out for 3-5 s, the subject is transferred to the orthostatic position n and 10 min, in which hyperventilation is carried out for 3 min, and in the absence of signs of orthostatic circulatory disorder and the presence of epileptiform patterns, epileptiform activity is diagnosed.