Electroencephalography (EEG) in adults and children
Electroencephalography (EEG) - a method of recording of the brain electrical potential fluctuations in adults and children, registered with the help of special devices - electroencephalographs. Apparatus for electroencephalography includes power amplifiers, allowing to obtain in a visual form of potential oscillations of the brain in adults or children with epilepsy amplitude of about 50 mV.
Measuring the potential of the human brain during the procedure of electroencephalography in adults and children produced through special electrodes located on the surface of the head of the international 10-20 system, which allows to place the electrodes in the areas of projection of different areas of the brain.
The electroencephalogram of the brain in healthy adults and children have traits from all areas of the cortex is given rhythmic activity with a frequency of about 10 Hz and an amplitude of 50-100 mV - alpha rhythm.
On the electroencephalogram in healthy adults and children are recorded other rhythms: as lower - delta and theta (2-4, 5-7 Hz) and higher - beta rhythms (13-30 sec) but their amplitude is normally low and they overlap the alpha waves.
Electroencephalogram in healthy adults and children varies with the functional state. For example, in the transition to sleep slow oscillations become dominant, and the alpha rhythm disappears. At strong excitation to the damage of the alpha rhythm revealed dramatic changes: they manifest themselves in enhancing slow oscillations, sometimes beta rhythms, impaired regularity and frequency of the alpha rhythm. These and other changes are nonspecific.
With the development of brain CT and MRI diagnostics electroencephalography in healthy adults and children lost its role in the objectification of local brain lesions. However, it remains essential to assess the functional state of the brain in various forms of epilepsy (generalized or localized convulsions with loss of consciousness) in different periods of severe brain injuries (TBI).
Electroencephalography (EEG) in adults and children
Often, for diagnostic purposes of the brain electroencephalography is prescribed without whatever clinical reason. For example a patient with a headache without seizures with loss of consciousness in the history may be sent to the EEG test by neurologists. The results of these studies do not bear unreasonable any clear information, and can only cause confusion in setting the correct diagnosis, lead to neurosis hypochondriac patients or the parents investigated in this incorrect way of children.
In the acute period of mild TBI observed blurred abnormalities mainly in the form of irregular alpha rhythm and gain frequent fluctuations with rapid regression of pathological changes in the electroencephalogram.
Changes in the electroencephalogram at moderate injury and severe traumatic brain injury in adults and children over rough, they take place in phases. Intensity of slow-rhythm fluctuations and impairments depend on the degree of involvement in the pathological process of stem structures, the presence of contusion foci and intracranial hematomas. In the projection display of contusion foci of slow activity depends on the location and distribution of the zone of injury.
Most serious local changes in the electroencephalogram of the brain, also against the backdrop of crude expression of brain changes are detected in the massive cortico-subcortical foci of contusion. Pathological changes in these cases have a tendency to grow during the first 5-7 days.
In the acute period with epidural hematoma expressed cerebral changes often absent; focal changes have circumscribed character of slow waves or local suppression of the alpha rhythm.
At subdural hematomas changes in the electroencephalogram of the brain in children and adults are diverse, characterized by significant common brain changes: the general oppression of activity, the presence of polymorphic delta waves during deceleration reduction and disorganization of the alpha rhythm, a manifestation of outbreaks of slow "pons"-type waves. Focal changes are characterized by a broad, unclear division. Often detected only hemispheric asymmetry without a clear focus.
At intracerebral hematomas on the electroencephalogram of the brain in adults and children appear expressed cerebral delta-theta waves. Focal changes in the area of the projection of hematoma - in the form of the predominance of slow waves.
Particular importance for the assessment of the status and prognosis is electroencephalography in severe traumatic brain injury, accompanied by a long coma. In these cases, changes in the electroencephalogram are varied and depend on the severity of the injury, the presence and localization of foci of contusion and intracranial hematoma.
For patients who have had a serious injury with reversible flow, characterized by phase change on the brain electroencephalogram in adults and children. At the initial stage - polyrhythm with a predominance of slow forms of activity, at least - reduction of the oscillation amplitude.
At the same time is typical the presence of sleep spindle (13-15 Hz) typical for the normal sleep, bilateral theta waves or low-frequency alpha rhythm, sharp waves on the background of the delta oscillation. Manifested hemispheric asymmetry, reactivity to stimuli weakened. There have been "pontine" flash of slow waves. In the future, when patient coming out from a coma, after a period of general decline in activity follows gradual activities recovery.
In severe TBI, which ended lethally, on the background of the deep impairments of consciousness and vital signs on the brain electroencephalogram in adults and children is dominated slow activity of slow waves to beta waves (alpha coma, beta coma), characterized by monotony, areactivity to stimuli, including pain, reduced regional differences. Focal slow waves in the area of contusion or hematoma does not appear. Typically low frequency (5 Hz) theta rhythm is predominance, indicating complete blockade in cortical activity and dominance of the regulation by the stem and subcortical brain structures.
In the late period of TBI electroencephalography determine a brain's seizure activity. Pathologic features on the electroencephalogram tend to persist longer, than clinical symptoms in patients. The recovery rate on the brain electroencephalogram is dependent on the severity of the it's injury. The most persistent changes in the electroencephalogram are in the area of contusion foci or former hematoma. In these areas of the brain are often formed epileptic activity.
Changes in the brain electroencephalogram in the long term of penetrating craniocerebral trauma may occur to a large extent over the years. They are both the general cerebral character, due to progress of hemodynamics impairment and liquor dynamics, with occurring local changes (epileptic or slow activity) in the area of primary brain damage.