Electric Nerve Blocks
Mark V. Boswell, B. Eliot Cole in Weiner's Pain Management, 2005
During the 20th century, electrical devices became generally accepted in medicine, initially for diagnostics. Most are familiar with electrocardiography (ECG), electroencephalography (EEG), and electromyography (EMG), including surface EMG (sEMG), and nerve conduction velocity (NCV) studies. Electrooculography, electroretinography, electronystography, electrocochleography, skin galvanics, and various evoked potentials are more specialized, although less well-known electrodiagnostic procedures (Northrup, 2001).
Minimal Recording Parameters and Extended Montage
Ravi Gupta, S. R. Pandi Perumal, Ahmed S. BaHammam in Clinical Atlas of Polysomnography, 2018
Some evidence suggests that a single EEG channel, that is, placement of central electrodes helps in optimal scoring of sleep stages, still the placement of three channels (along with three back-up channels) is considered gold standard.Electrooculogram (EOG): An EOG that records the movement of the eyeball is also recorded from both eyes. Having the data from both eyes not only prevents the data loss in case of fall-off of lead but also clearly delineates the eye-movement. For the reasons discussed in Chapter 3 (section on EOG), true eye movement is always in the opposite phase, that is, if one channel deflects towards the negative side, the other deflects towards the positive side (Figure 9.8). Since these channels are placed close to the frontal area, sometimes, delta waves may be spilled in these channels, giving the impression of eye movement (Figure 9.9). Eye movements, along with EEG, help in scoring wakefulness, quiet wakefulness, and REM sleep.Electromyogram (EMG):Muscle tone: An EMG is required to score the sleep stage as well as the abnormal movements during sleep. During wakefulness, muscles have a basal tone that reduces as well fall asleep . REM sleep is characterized by profound atonia, however, in patients with REM sleep behavior disorder, this atonia is not seen. Submentalis muscle has been chosen because it is a skeletal muscle, lies just beneath the skin, thus, provides good signals, and normally remains inactive during sleep, in contrast to other skeletal muscles that may get activated episodically during sleep. To prevent data loss, signals are recorded from sub-mentalis/mentalis muscles of both sides. Along with EEG, these signals help in recognizing REM sleep stage and REM sleep without atonia.Limb movements: To record the periodic limb movement during sleep (PLMS), signals are recorded from anterior tibialis muscles of both legs. To minimize data loss, signals are recorded from both legs separately (Figure 9.10). In addition, signals from both sides should not be combined as it may reduce the detectable numbers of limb movements. These signals, along with the EEG, help in scoring PLMS-associated arousals. In addition, these signals also help in scoring “alternate leg muscle activity” (ALMA), Hypnogogic foot tremors (HFT), and excessive fragmentary myoclonus (EFM).Respiratory Flow: Respiratory flow is an important signal to score apnea and hypopnea. It is measured using a thermistor and a pressure transducer (Figure 9.11). As discussed in Chapter 3, the thermistor is important for the diagnosis of apnea while a pressure transducer helps in recognizing hypopnea, Cheyne-Stokes breathing, and periodic breathing.
EEG of patients in coma after traumatic brain injury reflects physical parameters of auditory stimulation but not its emotional content
Published in Brain Injury, 2019
Galina V. Portnova, Michael. S. Atanov
During the EEG recording the subjects sat in a comfortable position in an armchair in an acoustically and electrically shielded chamber, the patients in coma laid in a hospital bed in a resuscitation unit. The participants were instructed to remain calm and to listen to the presented sounds keeping the eyes closed (to avoid visual interference) and avoiding falling asleep. The stimuli were presented via earphones. EEG was recorded using a device ‘Encephalan’ (Medicom MTD, Taganrog, Russian Federation) with the recording of polygraphic channels (though these data are not presented). 19 AgCl electrodes (Fp1, Fp2, F7, F3, Fz, F4, F8, T3, C3, Cz, C4, T4, T5, P3, Pz, P4, T6, O1, O2) were placed according to the International 10–20 system. The electrodes placed on the left and right mastoids served as joint references under unipolar montage. The vertical electrooculogram (EOG) was measured with AgCl cup electrodes placed 1 cm above and below the left eye, and the horizontal EOG was measured with electrodes placed 1 cm lateral from the outer canthi of both eyes. Amplifier sampling rate was 250 Hz, the filtering was set to bandpass 1.6–30 Hz. The electrode impedances were maintained at less than 10 kΩ.
Decreased resting gamma activity in adult attention deficit/hyperactivity disorder
Published in The World Journal of Biological Psychiatry, 2019
László Tombor, Brigitta Kakuszi, Szilvia Papp, János Réthelyi, István Bitter, Pál Czobor
EEG was recorded using a 128-channel Biosemi Active Two System (Biosemi, Amsterdam, the Netherlands) in a sound-attenuated room. Participants were not allowed to take caffeine or to smoke 2 h prior to EEG-recording, but they took their daily medication as usual. Participants were instructed to sit calmly with eyes open during the 4-min resting-state EEG recording. Electrooculogram (EOG) was recorded using two electrodes placed over and below the outer canthi. EEG was digitised with a sampling rate of 1024 Hz. Preprocessing was performed using EMSE Suite (Source Signal Imaging, San Diego, CA, USA). Data were band-pass filtered between 0.5 and 70 Hz and notch filtered at 50 Hz. An automatic ocular artefact rejection was performed. After preprocessing, all EEGs were visually inspected, and epochs containing artefacts were removed from further processing. Channels containing artefacts were marked and removed from analysis, and their data were replaced with interpolated voltage data. Artifact free, 2500-ms epochs were used for Fourier transformation. Similar to prior studies (Barry et al. 2010; Dupuy et al. 2014), we focussed on the low gamma frequency band, ranging between 30 and 48 Hz. The target band was divided into two symmetrical frequency bins, 30.25–39 and 39.25–48 Hz, henceforth gamma1 and gamma2. Power spectrum data were further processed in second level analyses (see below).
Effects of depression and past-year binge drinking on cognitive control processes during a flanker task in college-aged adults
Published in The American Journal of Drug and Alcohol Abuse, 2018
Arin M. Connell, Sarah Danzo, Glen Dawson
EEG data were recorded with a Biopac MP 150 system from 11 scalp sites (F3, Fz, F4, C3, Cz, C4, P3, Pz, P4, O1, and O2), and the right-ear, with a left-ear reference and common-ground sensor at FCz, using tin electrodes in an Electro-Cap International cap following the international 10/20 placement system. Electrode impedances were below 5 kΩ. Data were recorded using a sampling rate of 500 Hz and gain of 2000 and re-referenced offline to an average-ear reference. Vertical electrooculogram (VEOG) data were recorded from the right eye, and blink artifacts were removed via independent component analyses (ICA; 38). EEG data were bandpass filtered with cutoffs of .1–30 Hz. Continuous data were epoched across a 200 ms baseline and 1000 ms post-stimulus. Baseline corrected trials were excluded if EEG exceeded ± 75 µV, using the MATLAB-based packages, ERP-Lab toolbox (www.erpinfo.org/erplab;39), and EEGlab (sscn.ucsd,edu/eeglab/; 40). ERP averages were created for congruent and incongruent trials using correct-response trials only.
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