1
Q
Frequências
A
- 8-13 Hz = alfa (vigília, mais proeminentes com o fechamento ocular)
- > 13 Hz = beta (pode ser aumentada po BZD, barbitúricos, sonolência e sono leve)
- 4-7 Hz = teta (aumentam com concentração, durante tarefas mentais, hiperventilação e sono)
- < 4 Hz = delta (sono, bebês e idosos)
2
Q
Conceitos Básicos
A
- sensitivity = gain - microvolts per millimeter
- epoch = time
- Posterior dominant rhythm (PDR) - relaxed and with eyes closed
Variations: temporal alpha (older patients), frontal alpha (drugs, anesthesia or following arousal from sleep) - if invariant and unreactive to any stimuli = pathological; alpha coma pattern - 10-20 electrode site placement strategy -> between nation and inion // and between auricular positions
3
Q
Achados Normais
A
- eye closure: eye is a dipole; with Bell phenomenon, cornea approaches frontal region -> positive potential (negative wave) followed by negative
- Mu rhythm -> alpha-range-frequency over central head regions, can be uni ou bilateral, prominent during drowsiness, reactive to movement (attenuate with thumb wiggle)
Can be seen in 20-40% normal adults - Lambda waves -> elicited by pattern viewing; positive wave occipitally predominant
- hyperventilation -> minimal change in adults
In children, adolescents and young adults -> normal finding = prominent high-amplitude ou hyper-synchronous background-slowing = “build-up” - photic stimulation -> no change or symmetrical “photic driving response”= entrainment of background alpha rhythm to the same harmonic frequency variant of administered flashing lights (posteriorly predominant)
Can be similar to ERG artifact -> retinal depolarization - more anterior and can be blocked by covering one eye
4
Q
Sono
A
- N1: V-waves, slow eye movement
- N2: K (knock) complexes = suppression of environmental sounds; sleep spindles (consolidation of memory - thalamus-cortical connections)
- SWS = repair: delta > 20%; slow frequency waves
- REM: desynchronized, REMs, sawtooth waves - making connections and replaying scenarios related to episodic memory
Neurologia - Epilepsia e EEG
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