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Treatment of Pressure Sores
Published in J G Webster, Prevention of Pressure Sores, 2019
The applied current is sometimes referred to as being galvanic or faradic (Patterson 1983). Galvanic current usually refers to a direct current (dc), which may be produced by a battery, and produces a net charge transfer. With faradic current there is no net charge transfer at the electrodes. Faradic current is an alternating current (ac) coupled output signal in which the same amount of charge flows alternately in both directions. The magnitudes of the current in each direction may be different, so long as the lower current is applied for a longer time so that the charge transferred in each direction is equal. The charge transferred may be found using
Technological Evolution of Wireless Neurochemical Sensing with Fast-Scan Cyclic Voltammetry
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
Dan P. Covey, Kevin E. Bennet, Charles D. Blaha, Pedram Mohseni, Kendall H. Lee, Paul A. Garris
The general principle of voltammetry is that a voltage is applied to the microsensor and the resulting current is measured [13]. Faradaic current, due to analyte oxidation (i.e., loss of electrons) and/or reduction (i.e., gain of electrons), quantifies analyte concentration. Voltammetric techniques differ in how potential is applied. Older methods for in vivo neurochemical monitoring, such as differential pulse voltammetry, scanned potential slowly, which limited temporal resolution to the minute domain. In contrast, modern voltammetric techniques such as amperometry, high-speed chronoamperometry, and FSCV sample with subsecond temporal resolution. When coupled to a carbon–fiber microelectrode (CFM), the present microsensor of choice for in vivo voltammetry, these techniques also afford micron spatial resolution. The cylindrical CFM shown in Figure 7.2 was fabricated by aspirating a single carbon fiber (r = 2.5 μm) into a glass microcapillary tube and pulling to a taper. The active sensing surface is that portion of the carbon fiber extending from the glass insulation (~100 μm).
Hysteria
Published in Francis X. Dercum, Rest, Suggestion, 2019
Electricity also may prove of much value in given cases, as it is in the treatment of neurasthenia. It is to be employed in a similar manner. The slowly interrupted faradaic current is conveniently used to stimulate the flexor and extensor muscles of the limbs and the muscles of the trunk; it promotes the general nutrition and increases the general level of the muscular tone. The rapidly interrupted faradaic current is sometimes used as a local stimulant, and is often very efficacious in dispersing painful stigmata. At other times the constant galvanic current may be used for this purpose, the anode being applied over the painful area. Again, in cases in which these areas persist, they sometimes disappear rapidly under static electricity, high-frequency or other modes of electrical application. Electricity, of course, acts under these circumstances by suggestion. We should remember, however, that sometimes electricity is as suggestive of harm as it is of good. After an incautious electric application, the patient may complain of various obscure or painful sensations, declaring that she has been made much worse, or perhaps has new symptoms, e.g., a palsy or a contracture, symptoms from which she may believe she will never recover. At other times, even when an exceedingly mild current is used, she will complain excessively of pain; indeed, she will not infrequently do this when the electrodes are not even connected with the battery. Further, the effect of an imposing apparatus is as likely to be bad as good. In respect to this, as to all other elements of the treatment, therefore, the question becomes finally one of good judgment in the individual case.
Jean-Martin Charcot´s medical instruments: Electrotherapeutic devices in La Leçon Clinique à la Salpêtrière
Published in Journal of the History of the Neurosciences, 2021
Francesco Brigo, Albert Balasse, Raffaele Nardone, Olivier Walusinski
On December 26, 1880, Charcot held a conference in Salpêtrière entitled “The Employment of Static Electricity in Medicine” (De l’emploi de l’électricité statique en médecine; Charcot 1881). His lesson began with an explanation of “the quantity and voltage” of the electricity implemented. Charcot presented the same device painted by Brouillet: “The induction devices, to which belong our faradic devices, provide quite high voltage in a relatively large quantity” (Charcot 1881). He then provided some examples of its use “in some lesions of the nerves or their trophic centers.” Charcot explained, “the galvanic current causes muscle contractions, and even more intense than in the normal state when it is impossible to achieve this contraction with faradic current in humans, at least after stimulation of the external teguments” (Charcot 1881). He finally referred his listeners to a memoir by Pierre Jean Étienne Mauduyt de La Varenne (1733–1792) published in 1780 (see Mauduyt de La Varenne 1780).
The Sherrington–Cushing connection: A bench to bedside collaboration at the dawn of the twentieth century
Published in Journal of the History of the Neurosciences, 2020
In his 1909 paper, two of these cases were described in detail and, tellingly, Cushing in these reports wished to emphasize the physiological observations made on these cases rather than the surgical ones: “It is the purpose of this paper to record solely the physiological aspects of these observations” (Cushing 1909). Case 1 was a 15-year-old boy with focal sensorimotor seizures involving the right hand and face. Cushing wrote: “With the presumption that some organic lesion, possibly a tumour of the postcentral territory, would be found, an exploration was advised” (Cushing 1909). Once the pre-central gyrus was exposed, Cushing used the opportunity to experiment with Faradic stimulation: “The following electrical observations were then made. The same movements as before were easily elicited with a mild faradic current from the precentral strip” (Cushing 1909).