Neurophysiologie clinique = Clinical neurophysiology
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Continuous EEG from critical care patients needs to be evaluated time efficiently to maximize the treatment effect. A computational method will be presented that detects rhythmic and periodic patterns according to the critical care EEG terminology (CCET) of the American Clinical Neurophysiology Society (ACNS). The aim is to show that these detected patterns support EEG experts in writing neurophysiological reports. ⋯ The use of automatic pattern detection will assist in review of EEG and increase efficiency. The implementation of bedside surveillance devices using our detection algorithm appears to be feasible and remains to be confirmed in further multicenter studies.
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We investigated effects of NREM and REM predominant sleep periods on sleepiness and psychomotor performances measured with visual analog scales and the psychomotor vigilance task, respectively. After one week of stable sleep-wake rhythms, 18 healthy sleepers slept 3hours of early sleep and 3hours of late sleep, under polysomnographic control, spaced by two hours of sustained wakefulness between sleep periods in a within subjects split-night, sleep interruption protocol. Power spectra analysis was applied for sleep EEG recordings and sleep phase-relative power proportions were computed for six different frequency bands (delta, theta, alpha, sigma, beta and gamma). ⋯ In addition, sleepiness remained stable throughout sustained wakefulness during both conditions, whereas psychomotor performances even decreased after the second sleep period. Disregarding exchanges for frequency bands in NREM or stability in REM, correlations between outcome measures and EEG power proportions further evidenced directional divergence with respect to sleepiness and psychomotor performances, respectively. Showing that the functional correlation pattern changed with respect to early and late sleep condition, the relationships between EEG power and subjective or behavioral outcomes might however essentially be related to total sleep duration rather than to the phasic predominance of REM or NREM sleep.
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Comparative Study
Visual processing during recovery from vegetative state to consciousness: comparing behavioral indices to brain responses.
Auditory stimulation is often used to evoke responses in unresponsive patients who have suffered severe brain injury. In order to investigate visual responses, we examined visual evoked potentials (VEPs) and behavioral responses to visual stimuli in vegetative patients during recovery to consciousness. ⋯ Our findings show the improvement of visual responding with recovery from the vegetative state to consciousness. Elementary visual processing is present, yet according to VEP responses, poorer in vegetative and minimally conscious state than in healthy controls, and remains poorer when patients recovered to consciousness. However, initial VEPs are related to long-term outcome.
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We here review behavioral, neuroimaging and electrophysiological studies of hypnosis as a state, as well as hypnosis as a tool to modulate brain responses to painful stimulations. Studies have shown that hypnotic processes modify internal (self awareness) as well as external (environmental awareness) brain networks. ⋯ Combined with local anesthesia and conscious sedation in patients undergoing surgery, hypnosis is associated with improved peri- and postoperative comfort of patients and surgeons. Finally, hypnosis can be considered as a useful analogue for simulating conversion and dissociation symptoms in healthy subjects, permitting better characterization of these challenging disorders by producing clinically similar experiences.
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Tremor and myoclonus are very common manifestations of psychogenic movement disorders (PMD). In this context, recording of movement disorders aims to provide objective criteria for a positive diagnosis of PMD, independently of the psychological situation. Neurophysiological observations are therefore considered to have a huge impact both on diagnosis and on therapeutic approaches. ⋯ Polymyography is critical to identify a ballistic pattern or a discordant or non-reproducible temporo-spatial organisation of the jerks, but has usually to be completed by other potentially decisive approaches. Reflex psychogenic myoclonus for example displays stimulus-response delays that are too long and variable. Spontaneous psychogenic jerks may be also preceded by a pre-movement potential, detectable by jerk-locked-back-averaging methods.