Normal Eeg Waves

March 27, 2018 | Author: vijaykalpana | Category: Electroencephalography, Sleep, Science, Physiology, Neuroimaging


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Normal EEG WAVESD KALPANA Click to edit Master subtitle style 4/17/12 HOW TO ANALYSE AN EEG  AGE STATE OF THE PATIENT  AWAKE DROWSY SLEEP SEDATED DELIRIOUS STUPOR OR COMA 4/17/12 ALERTING SOUND ETC TRANSIENTS RESPONSE TO ACTIVATION PROCEDURES 4/17/12 . MENTAL ARITHMETIC.FACTORS TO BE ANALYSED BACKGROUND ACTIVITY THE FREQUENCY AMPLITUDE SYMMETRY SYNCHRONY REPONSE TO EYE OPENING. NOMENCLATURE ALPHA BETA THETA DELTA GAMMA 4/17/12 . BASIC EEG RHYTHMS ALPHA – 8-13 HZ BETA .< 4 HZ 4/17/12 .> 14 HZ THETA – 4-7 HZ DELTA . 4/17/12 . ALPHA RHYTHM Normal background rhythm in the posterior head region 8-13 hz 20-50 uv In normal adult in the relaxed state with eyes closed Fairly symmetrical and synchronous Symmetry – same amplitude 4/17/12 Normally higher amplitude in right hemisphere . ALPHA RHYTHM continued same between hemispheres Synchrony – the frequency should be the A difference of 1hz or more is significant Often the slower frequency is on the abnormal side Alpha drop out – decrease in amplitude of alpha during drowsiness Spontaneous modulations present. 4/17/12 . Attenuation of alpha rhythm in response to ALPHA BLOCKING alerting stimuli Eye opening Mental arithmetic Loud sound Lack of attenuation to alerting response is sign of abnormality. 4/17/12 . 4/17/12 . MATURATION OF BACKGROUND RHYTHM 4/17/12 . may attain amplitude over 25 microvolts 4/17/12 Often enhanced during drowsiness or when . related to the functions of the sensorimotor cortex.  The generalized beta activity: induced or enhanced by drugs.  Average voltage is 10-20 microvolts  Two main types in adults:  The precentral type: predominantly over the anterior and central regions. if >30-35 Hz  gamma activity or exceedingly fast activity by Gibbs.Beta rhythm  Frequency of over 13 Hz. Beta rhythm Mostly seen in the anterior leads The rhythm of the alert brain 4/17/12 . sleep 4/17/12 .Theta wave rhythmic. 4-7 Hz Drowsy. 5 Hz in adults normal sleep rhythm – stage 3 & 4 In stupor and coma Encephalitis and postictal state 4/17/12 .Delta wave slow. < 3. 4/17/12 . Occipital region Adult. rest.Different types of brain waves in normal EEG Rhythm Frequency Amplitude (Hz) (uV) 8 – 13 50 – 100 Recording & Location Adults. eyes closed. mental activity Frontal region Children. emotional distress Occipital Children in sleep Alpha(α) Beta(β) Theta(θ) Delta(δ) DTAB 14 .30 20 5–7 Above 50 2–4 Above 50 . drowsy adult. Factor influencing EEG Age Infancy – theta. delta wave Child – alpha formation. Hypoglycemia 4/17/12 Hypothermia Slow waves . Level of consciousness (sleep) Hypocapnia(hyperventilation) slow & high amplitude waves. Adult – all four waves. Changes in brain waves during different stages of sleep & wakefulness 4/17/12 . Changes in brain waves during different stages of sleep & wakefulness 4/17/12 . 4/17/12 . K .complex Sleep Spindle 4/17/12 . Thank you 4/17/12 .
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