The brain nerve cells are constantly in a spontaneous and rhythmic discharge, which is called brain waves. Cell EEG tracings method is application of electronic amplification technology to enlarge the brain electrical activity of 100 million times, by the difference in potential between two points on the scalp or scalp and independent between electrodes or special electrode potential difference tracings from EEG line, clinically known for EEG solid (EEG), to study the brain function. The spatial characteristics of EEG for brain waves as the vertical axis, with time characteristics and displayed as a cross of uranium. Several basic characteristics of EEG is frequency, amplitude, waveform, phase, adjusting and amplitude modulation, brainwave of form and distribution, this is the basis of clinical EEG analysis.
(1) frequency
(1) a wave from baseline to it returned to baseline time period, namely the wave bee to the crest of the wave, or trough to trough time unit in milliseconds (MS).
The number of weeks per second is called the frequency, with Hz ratio. 10 V above the wave in the last 1 minutes of the percentage of the index, such as a rhythm within 15 minutes of 1 seconds, the index is 15/60, that is, 25%.
(2) amplitude
A wave from the peak to baseline amplitude with distance, Microvolt (V) said. EEG amplitude usually in occipital description write out the basic rhythm wave height is standard, such as < U V said low amplitude, (25-50 or) U V amplitude, 50 or 75) - 100 mu V plateau amplitudes, 150 mu V above is extremely high amplitude. In normal adults, the occipital region was higher than that in the frontal part, and the dominant side of the minority was lower than that of the non dominant side, but the difference was not more than 30%.
(3) waveform
EEG can be due to the frequency, amplitude and potential changes and the formation of a variety of waveforms, such as sine or sine like wave, semi arc shape wave, sawtooth wave, double humped wave, spike wave, sharp, sharp and slow are.
(4) phase
A wave can be generated by the deflection of the vertical phase. Single phase being: a case of a case of a deflection. The dual phase wave: first to a baseline and then to all the other cases of deflection deflection. Multi phase wave: a wave of wave from the baseline repeatedly to the sides of the deflection. The upward deflection of the negative wave, downward deflection of the positive phase wave. The two lead electrocardiography, the relationship between the amplitude of time can produce phase difference. As the two lead of the amplitude by baseline upward or downward deflection, the phase difference of 0 degrees out of phase ". On the contrary, the difference of 90 degrees is
Different phase. As the wave of the two pilot is deflected in the opposite direction at the same time, the difference is 180 degrees, then it is called the phase inversion. It can be used as the localization of brain lesions.
(5) adjustment and modulation
1 adjustment: EEG refers to the basic frequency of occurrence regularity and stability. In the same parts of the fundamental frequency is stable, the difference between before and after should not be more than 1 times / sec, such as 2 times / seconds or more should regarded as adjustment; on the left and right hemisphere symmetric parts of the same time shall not be more than 0.5 times / sec, more than 1 times / sec for differential regulation.
II am: refers to the brain is the basic collar on the regularity of the change in volatility and a normal spindle form and amplitude of high, low, every 3-5 seconds will change, such as spindle shaped. Said the amplitude modulation phenomenon. Rules such as amplitude increased and showed a decreased spindle change makers, for am good, if there is no change in the amplitude or uneven lose regular am bad.
(6) brain wave form and distribution in the EEG single potential difference is called wave, the wave called activities, with relatively constant cycle and shape, and regular recurring activity known as the rhythm. In EEG tracings, in addition to paroxysmal or limited significant changes, the rest of the performance for more or less diffuse and special activities constitute the background electrical activity, such as. Rhythm and 9 rhythm. The background of children activities were generally Sakura, older children or in yo spring period. Rhythm, but also a certain slow wave. But by man into pathological conditions.
Two or more wave groups, which can be clearly distinguished from background activity and have a certain wave shape, are known as composite. Wave frequency, amplitude, waveform suddenly change and disappear suddenly called paroxysmal activity. The mutual change of different amplitude of the fast Sakura or slow wave is called the law of failure. Hypsarrhythmia is refers to the EEG waveform, amplitude, wave on regularity and amplitude increased, miscellaneous to tip Peter, spikes, found in spasms of the strike.
Brain is the form, from the time sequence can be single, Che in, short (less than 1 second) and long range (more than 1 second), sustained, paroxysmal, messy, am (amplitude is spindle shaped). From the spatial distribution can be diffuse (also known as widespread or universal, that is, in all regions of the head), dispersion (appeared in most of the head region), asymmetric, and limited to the side.
EEG brainwave constitute what is?
(1) alpha (alpha) wave
8-13Ib, the majority of normal people is the frequency of 9 - 10Hz, the amplitude of 10-100 V, an average of 50 V sine wave. In the top, pillow area. Activity
The most obvious, the basic rhythm for normal adults.
The clinical significance of:. Wave in the awake and quiet eyes closed that eyes, attention, thinking, or accept other stimuli, alpha wave disappeared and fast wave of low amplitude, which is known for alpha blockade. Right at the end of more than 30% of normal below the right-handed people left amplitude, lower left alpha amplitude is due to the impulse is beneficial to human to human transmission of the left hemisphere more and improve the left cortical tension caused by. The difference between the two is still at a rate of 15% per second in the O.5 week, and the time of the alpha wave is called an index, and the individual asks a lot of differences from o-100, but the difference between the individual and the individual is not normal. Alpha wave and on both sides of the trough generally can be connected into an isosceles triangle, if the peak to the left or right shift due to the destruction of the morphology of the isosceles, prompting the central in a state of fatigue. The alpha wave is not only produced in the top and the occipital region, but also has an activity in the frontal part, but because the frontal area is involved in the regulation of the activation process which is the basis of the random attention, it obtains the synchronous reaction.
3 alpha rhythm advantage may have the following characterization, Ruyi knowledge and a higher level of activity, strong ability to work; emotional stability, calm; emotional color, well-informed, diligent in thinking, down-to-earth, good image of specific and creative activities; do things methodically, the plan, patient, perserve. The alpha rhythm of the dominant adult is about 57.5%.
(2) beta (beta) wave
The characteristics: frequency in 14-30Hz, amplitude of 5-20 Mu V, not more than 50 mu V, tip sample negative wave, in the frontal, temporal and central beta activities member is obvious.
II clinical significance: beta rhythm is not affected by the influence of eyes. When the attention, emotional stress, anxiety or sleeping pills export activities can be increased sharply. It is usually considered that the increase of excitability of cortical neurons can lead to the low volatility and fast frequency of the activity. About 6% of the normal subjects were mainly based on beta wave.
3 beta rhythm advantage is often shown as: mental stress, emotional instability, easy impulse, opinionated, longer than abstract thinking. Good rest on reasoning to solve problems; good at independent task execution; poor endurance, easy fatigue.
(3) 0 (theta) wave
Features: frequency in 4-7Hz, amplitude of 20-40 U V, found in parietal, frontal and temporal region, normal adult percentage theta is generally not more than 10% - 15%.
The clinical significance of light sleep: when theta theta often disappears gradually, at first appeared in two cases of forehead. Deep in such subcortical lesions can produce theta rhythms often exist on both sides of the explosive, focal theta rhythm, is not normal.
(4) Delta (delta) wave
Features: the frequency of 4Hz, amplitude of 10-200 v.
The clinical significance of the clinical significance: when the delta wave appears in the normal sleep, the representative of the cortical tension is reduced, and the delta wave in the infant and young children is normal. The local focal delta
Wave, regardless of any age, any level of consciousness were abnormal, indicating that the cortical lesions, bilateral and explosive delta rhythm often subcortical lesions.
Theta and delta are belong to the slow wave sleep period, found in normal infants to children and adults. In the pathological state, the limitations of the slow wave are limited in the diagnosis of focal epilepsy, brain tumor, brain abscess, brain injury hematoma and cerebral vascular disease. Diffuse but active in some infections, poisoning, low blood sugar, high intracranial pressure and various causes of coma, etc.. Slow activity is also a reflection of the inhibition of the brain, and the decrease of the amplitude of the slow activity is inhibited. But the shape of the activity can be divided into three kinds: the activity of the activity of the activity of the activity of the activity: it is a kind of slow activity with no fixed shape. In the area where the lesion is said to represent the lesion in the superficial or near the electrode. The mixed steamed bread; is a kind of slow activity overlapping with alpha or beta activity activity. In the case of limitation, the lesion is indicated in the deeper part of the cortex or in the distal part of the electrode. The sine of slow rhythm: also known as slow rhythm monomorphic activities, often paroxysmal, came from the depths of focus. Such as paroxysmal and bilateral synchronous, often expressed in the midline or posterior fossa lesions. Such as localized in the lesions of the midline, especially thalamic lesions without increased intracranial pressure, and often for theta rhythm, if indirect effects of thalamus and midbrain lesions associated with intracranial hypertension, often appear paroxysmal theta rhythm.
The spike wave is rapidly rising and falling, and the period is shorter than 80ms, which is negative. Spike is nerve cells in the cerebral cortex hyperexcitability performance, found in focal epilepsy and the multi spike wave appears the myoclonic seizures.
Sharp wave is also called sharp wave, is a period longer than the 80ms 200ms of the triangle wave, and the inherent difference between the background of the brain, there are limitations of epilepsy. Three phase (tip) wave occurs in hepatic coma.
Spike and slow wave from a spike wave and a slow are composed of complex wave, spike wave cycle short to 80ms, slow wave cycle in 200-500ms, limitations of epilepsy. Bilateral symmetric synchronous 3Hz continued to have regular spike and slow rhythms in seizures.
Multi spike wave has more than two spikes and a slow wave complex, myoclonic seizures occurred in.
The sharp slow wave complex is composed of a pointed wave and a slow wave, and the period of the sharp wave is between 80-200ms and the Man Bo period is between 500-1000ms.
