Identification of sensory blockade by somatosensory and pain-induced evoked potentials.

Background: To date, the anesthesia-induced blockade of nociceptive inputs is insufficiently reflected by commercially available electroencephalographic depth-of-anesthesia monitors. The aim of the current study was to evaluate the potential of somatosensory (SSEP) and intracutaneous pain evoked (iSEP) potentials during remifentanil and propofol anesthesia as electroencephalographic indicators of the nociceptive blockade.

Methods: Ten healthy men were investigated in a double-blind crossover design during three sessions with remifentanil, propofol, and placebo administration.

Duration of the cue-to-pain delay increases pain intensity: a combined EEG and MEG study.

Expectation of pain is an important adaptive process enabling individuals to avoid bodily harm. It reflects the linking of past experience and environmental cues with imminent threat. In the present study, we examined changes in perceived pain contingent upon variation of the interval between an auditory cue and a subsequent painful laser stimulus.

MEG and EEG show different sensitivity to myogenic artifacts.

Simultaneous measurements of EEG, MEG and EMG were performed during randomized blocks with higher and lower muscular stress in comparison to baseline condition. Power spectral density PSD was analyzed separately for five intervals (theta, delta, alpha, beta, gamma). During increased muscular stress, a significant increase could be observed in most bands of EEG while MEG showed no significant changes.

Dissociation of morphine analgesia and sedation evaluated by EEG measures in healthy volunteers.

Aim: The analgesic effects of morphine (CAS 57-27-2) in clinical use are well described. Sedation is discussed as a relevant side-effect, mostly based on data recorded in normal subjects without pain. The aim of this study was to quantify and to evaluate electrophysiologically the analgesic and sedative effects of morphine for the first time using an experimental pain model.