Electroencephalographic EEG Changes

Deep anesthesia with enflurane is associated with the appearance of seizurelike electroencephalographic (EEG) changes. Occasionally frank tonic-clonic seizures are observed. Consequently, other inhalational agents are usually given to patients with preexisting seizure disorders. 

Electroencephalographic (EEG), electro-oculographic (EOG) and electromyelographic (EMG) feature characteristic of the stages of sleep (NREM stages 1-4 and REM) and wake. The distinctions between REM and NREM sleep are dramatic and qualitative, including differences in EEG and EOG patterns, changes in heart... 

Alterations in neurophysiological activity are subserved by many of the neurotransmitters discussed earlier in this section, as well as in Mechanism of Action in Chapter 7. After repeated seizures spaced over a given period of time (usually two to three times per week over a 3- to 5-week period), there is an increase in cerebral blood flow (primarily the result of increased systemic circulation) and an acute and sustained increase in cerebral metabolism. One of the most characteristic changes is a slowing in the electroencephalographic (EEG) pattern over a series of ECT treatments, associated with increased acetylcholine activity. Increases in amplitude and decreases in frequency appear to affect thalamocortical and diencephalic structures, which may modulate recently acquired behavior, such as psychosis or melancholic features. 

Information is scanty on the electroencephalographic (EEG) effects in humans who have been severely poisoned by ChE-inhibiting substances. In an early study,80 DFP, administered intramuscularly daily, caused EEG changes in 19 of 23 subjects (19 normal, 4 with myasthenia gravis). The changes were... 

Figure 8 Mean changes over baseline in percentage of EEG amplitude falling in the beta frequency range (13-30 cycles/sec) during each of the five trials, as discussed in the text and in Fig. 4. Abbreviations EEG, electroencephalographic TRZ, triazolam CLAR, clarithromycin ERY, erythromycin AZ, azithromycin PL, placebo. Source From Ref. 77.

Thiopental exhibits enantioselectivity in its EEG effects [199,200]. After the continuous infusion of thiopental enantiomers administered separately to rats [199], the lethality anesthetic potency ratio of doses was significantly lower for S-thiopental (2.1) than for antipode (3.2). The authors also found that initial electroencephalographic changes were greater for... 

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