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C Maier - One of the best experts on this subject based on the ideXlab platform.
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reflex sympathetic dystrophy Skin blood flow sympathetic vasoconstrictor reflexes and pain before and after surgical sympathectomy
Pain, 1996Co-Authors: Ralf Baron, C MaierAbstract:To examine the pathophysiological mechanisms of vascular disturbances and to assess the role of the sympathetic nervous system, 12 patients with reflex sympathetic dystrophy (RSD) of the hand were studied using laser Doppler flowmetry. Cutaneous blood flow, Skin Resistance and Skin temperature were measured at the affected and contralateral hands. Sympathetic vasoconstrictor reflexes were induced bilaterally by deep inspiration. Four patients were treated with unilateral surgical sympathectomy and pain and vascular changes were documented in follow-up investigations. (1) After acclimatization in cold environment (< or = 18 degrees C) blood flow and Skin temperature were considerably lower on the affected side in 10 patients. No additional vasoconstrictor reflexes could be elicited. (2) After acclimatization in warm environment (22-24 degrees C) blood flow and Skin temperature demonstrated no side differences in all cases. Vasoconstrictor responses were the same on both sides. (3) After sympathectomy vasoconstrictor reflexes were absent. Skin Resistance was considerably higher on the affected side. In the first 4 weeks the affected hand was warmer and blood flow was higher compared with the healthy side. Thereafter, Skin temperature and perfusion slowly decreased and the affected hand turned from warm to cold. Very regular high amplitude vasomotion waves occurred unilaterally. There were no signs of reinnervation. Two patients had long-term pain relief. We conclude as follows. (1) Side differences in Skin temperature and blood flow are no static descriptors in RSD. They are dynamic values depending critically on environmental temperature. Therefore, they have to be interpreted with care when defining reliable diagnostic criteria. (2) Vascular disturbances in RSD are not due to constant overactivity of sympathetic vasoconstrictor neurons. Changes in vascular sensitivity to cold temperature and circulating catecholamines may be responsible for vascular abnormalities. Alternatively, RSD may be associated with an abnormal (side different) reflex pattern of sympathetic vasoconstrictor neurons due to thermoregulatory and emotional stimuli generated in the central nervous system. (3) After sympathectomy, denervation supersensitivity of blood vessels and intense vasomotion may be associated with recurrence of pain in some patients.
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reflex sympathetic dystrophy Skin blood flow sympathetic vasoconstrictor reflexes and pain before and after surgical sympathectomy
Pain, 1996Co-Authors: Ralf Baron, C MaierAbstract:Abstract To examine the pathophysiological mechanisms of vascular disturbances and to assess the role of the sympathetic nervous system, 12 patients with reflex sympathetic dystrophy (RSD) of the hand were studied using laser Doppler flowmetry. Cutaneous blood flow, Skin Resistance and Skin temperature were measured at the affected and contralateral hands. Sympathetic vasoconstrictor reflexes were induced bilaterally by deep inspiration. Four patients were treated with unilateral surgical sympathectomy and pain and vascular changes were documented in follow-up investigations. (1) After acclimatization in cold environment (≤18 °C) blood flow and Skin temperature were considerably lower on the affected side in 10 patients. No additional vasoconstrictor reflexes could be elicited. (2) After acclimatization in warm environment (22–24°C) blood flow and Skin temperature demonstrated no side differences in all cases. Vasoconstrictor responses were the same on both sides. (3) After sympathectomy vasoconstrictor reflexes were absent. Skin Resistance was considerably higher on the affected side. In the first 4 weeks the affected hand was warmer and blood flow was higher compared with the healthy side. Thereafter, Skin temperature and perfusion slowly decreased and the affected hand turned from warm to cold. Very regular high amplitude vasomotion waves occurred unilaterally. There were no signs of reinnervation. Two patients had long-term pain relief. We conclude as follows. (1) Side differences in Skin temperature and blood flow are no static descriptors in RSD. They are dynamic values depending critically on environmental temperature. Therefore, they have to be interpreted with care when defining reliable diagnostic criteria. (2) Vascular disturbances in RSD are not due to constant overactivity of sympathetic vasoconstrictor neurons. Changes in vascular sensitivity to cold temperature and circulating catecholamines may be responsible for vascular abnormalities. Alternatively, RSD may be associated with an abnormal (side different) reflex pattern of sympathetic vasoconstrictor neurons due to thermoregulatory and emotional stimuli generated in the central nervous system. (3) After sympathectomy, denervation supersensitivity of blood vessels and intense vasomotion may be associated with recurrence of pain in some patients.
Ralf Baron - One of the best experts on this subject based on the ideXlab platform.
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reflex sympathetic dystrophy Skin blood flow sympathetic vasoconstrictor reflexes and pain before and after surgical sympathectomy
Pain, 1996Co-Authors: Ralf Baron, C MaierAbstract:To examine the pathophysiological mechanisms of vascular disturbances and to assess the role of the sympathetic nervous system, 12 patients with reflex sympathetic dystrophy (RSD) of the hand were studied using laser Doppler flowmetry. Cutaneous blood flow, Skin Resistance and Skin temperature were measured at the affected and contralateral hands. Sympathetic vasoconstrictor reflexes were induced bilaterally by deep inspiration. Four patients were treated with unilateral surgical sympathectomy and pain and vascular changes were documented in follow-up investigations. (1) After acclimatization in cold environment (< or = 18 degrees C) blood flow and Skin temperature were considerably lower on the affected side in 10 patients. No additional vasoconstrictor reflexes could be elicited. (2) After acclimatization in warm environment (22-24 degrees C) blood flow and Skin temperature demonstrated no side differences in all cases. Vasoconstrictor responses were the same on both sides. (3) After sympathectomy vasoconstrictor reflexes were absent. Skin Resistance was considerably higher on the affected side. In the first 4 weeks the affected hand was warmer and blood flow was higher compared with the healthy side. Thereafter, Skin temperature and perfusion slowly decreased and the affected hand turned from warm to cold. Very regular high amplitude vasomotion waves occurred unilaterally. There were no signs of reinnervation. Two patients had long-term pain relief. We conclude as follows. (1) Side differences in Skin temperature and blood flow are no static descriptors in RSD. They are dynamic values depending critically on environmental temperature. Therefore, they have to be interpreted with care when defining reliable diagnostic criteria. (2) Vascular disturbances in RSD are not due to constant overactivity of sympathetic vasoconstrictor neurons. Changes in vascular sensitivity to cold temperature and circulating catecholamines may be responsible for vascular abnormalities. Alternatively, RSD may be associated with an abnormal (side different) reflex pattern of sympathetic vasoconstrictor neurons due to thermoregulatory and emotional stimuli generated in the central nervous system. (3) After sympathectomy, denervation supersensitivity of blood vessels and intense vasomotion may be associated with recurrence of pain in some patients.
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reflex sympathetic dystrophy Skin blood flow sympathetic vasoconstrictor reflexes and pain before and after surgical sympathectomy
Pain, 1996Co-Authors: Ralf Baron, C MaierAbstract:Abstract To examine the pathophysiological mechanisms of vascular disturbances and to assess the role of the sympathetic nervous system, 12 patients with reflex sympathetic dystrophy (RSD) of the hand were studied using laser Doppler flowmetry. Cutaneous blood flow, Skin Resistance and Skin temperature were measured at the affected and contralateral hands. Sympathetic vasoconstrictor reflexes were induced bilaterally by deep inspiration. Four patients were treated with unilateral surgical sympathectomy and pain and vascular changes were documented in follow-up investigations. (1) After acclimatization in cold environment (≤18 °C) blood flow and Skin temperature were considerably lower on the affected side in 10 patients. No additional vasoconstrictor reflexes could be elicited. (2) After acclimatization in warm environment (22–24°C) blood flow and Skin temperature demonstrated no side differences in all cases. Vasoconstrictor responses were the same on both sides. (3) After sympathectomy vasoconstrictor reflexes were absent. Skin Resistance was considerably higher on the affected side. In the first 4 weeks the affected hand was warmer and blood flow was higher compared with the healthy side. Thereafter, Skin temperature and perfusion slowly decreased and the affected hand turned from warm to cold. Very regular high amplitude vasomotion waves occurred unilaterally. There were no signs of reinnervation. Two patients had long-term pain relief. We conclude as follows. (1) Side differences in Skin temperature and blood flow are no static descriptors in RSD. They are dynamic values depending critically on environmental temperature. Therefore, they have to be interpreted with care when defining reliable diagnostic criteria. (2) Vascular disturbances in RSD are not due to constant overactivity of sympathetic vasoconstrictor neurons. Changes in vascular sensitivity to cold temperature and circulating catecholamines may be responsible for vascular abnormalities. Alternatively, RSD may be associated with an abnormal (side different) reflex pattern of sympathetic vasoconstrictor neurons due to thermoregulatory and emotional stimuli generated in the central nervous system. (3) After sympathectomy, denervation supersensitivity of blood vessels and intense vasomotion may be associated with recurrence of pain in some patients.
Keith A Christian - One of the best experts on this subject based on the ideXlab platform.
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Skin Resistance to water gain and loss has changed in cane toads rhinella marina during their australian invasion
Ecology and Evolution, 2020Co-Authors: Georgia K Kosmala, Gregory P Brown, Richard Shine, Keith A ChristianAbstract:The water-permeable Skin of amphibians renders them highly sensitive to climatic conditions, and interspecific correlations between environmental moisture levels and rates of water exchange across the Skin suggest that natural selection adapts hydroregulatory mechanisms to local challenges. How quickly can such mechanisms shift when a species encounters novel moisture regimes? Cutaneous Resistance to water loss and gain in wild-caught cane toads (Rhinella marina) from Brazil, USA (Hawai'i) and Australia exhibited strong geographic variation. Cutaneous Resistance was low in native-range (Brazilian) toads and in Hawai'ian populations (where toads were introduced in 1932) but significantly higher in toads from eastern Australia (where toads were introduced in 1935). Toads from recently invaded areas in western Australia exhibited cutaneous Resistance to water loss similar to the native-range populations, possibly because toads are restricted to moist sites within this highly arid landscape. Rates of rehydration exhibited significant but less extreme geographic variation, being higher in the native range than in invaded regions. Thus, in less than a century, cane toads invading areas that impose different climatic challenges have diverged in the capacity for hydroregulation.
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not just small wet and cold effects of body size and Skin Resistance on thermoregulation and arboreality of frogs
Ecology, 2010Co-Authors: Christopher R Tracy, Keith A Christian, Richard C TracyAbstract:We used simulations from a biophysical model that integrates interlinked exchanges of energy and water between frogs and their environments to address questions about the limits to thermoregulation and about adaptations for arboreality. Body size and cutaneous Resistance (Rc) both significantly affected body temperature (Tb) and the time to desiccate to 70% of standard mass (an ecologically relevant metric of desiccation). Cutaneous Resistances < 25 s/cm allow baSking frogs to elevate their Tb several degrees above ambient, but Rc above 25 had little additional effect on Tb. Small frogs (<10 g) are able to elevate their Tb above ambient while baSking, even with small Rc. Large frogs must have greater Skin Resistances to be able to elevate body temperatures above ambient, yet large frogs take longer to desiccate to 70% of their standard mass. Frogs can avoid rapid desiccation with high Rc, a large body size, or some combination of these traits. Our literature survey indicates that frogs with a combination of Rc and body size that would result in long times to desiccate to 70% of standard mass tend to be arboreal, suggesting that those species may be selectively favored in a niche that often requires frogs to be away from water sources for extended periods of time.
B G Wallin - One of the best experts on this subject based on the ideXlab platform.
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neuroeffector characteristics of sweat glands in the human hand activated by regular neural stimuli
The Journal of Physiology, 1991Co-Authors: M Kunimoto, K Kirno, Mikael Elam, B G WallinAbstract:1. Intraneural electrical stimuli (0.3-1.2 mA, 0.2 ms) were delivered via a tungsten microelectrode inserted into a cutaneous fascicle in the median nerve at the wrist in twenty-eight normal subjects. The effects on sweat glands within the innervation zone were monitored as changes of Skin Resistance and water vapour partial pressure (WVPP). Regional anaesthesia of the brachial plexus in the axilla eliminated spontaneous sympathetic activity and reflex effects. 2. At stimulation frequencies of 0.1 Hz each stimulus evoked a transient Skin Resistance reduction, the amplitude of which varied initially but reached a steady state of less than 10 k omega after, on average, nine responses. If preceded by stimulation-free intervals of 5 min or more, up to fifteen stimuli were required before the first response occurred. With higher frequencies individual responses started to merge, Skin Resistance levels decreased successively and levelled off around 10 Hz. The total change of Resistance (0-10 Hz) was 101 +/- 46 (n = 9) k omega and the higher the pre-stimulus level, the larger the reduction (r = 0.68, P less than 0.05). 3. Stimulus-response latencies to the onset of a Skin Resistance reduction (single stimuli or trains of six impulses/20 Hz given at 0.1 Hz) shortened initially but reached steady-state values after on average nine to twelve impulses. Average conduction velocity between stimulating electrode and Skin Resistance recording site was 0.78 m/s and average time for electrical neuroeffector transfer in sweat glands was estimated to be 348 ms. 4. In addition to direct stimulation-induced Resistance responses there were also small spontaneous reductions of Resistance. They were seen in all subjects and at all frequencies but were more common in some subjects and occurred predominantly at the beginning of stimulation or at changes of frequency. They occurred independently at two Skin sites in the same subject and disappeared during stimulation-free periods and after atropine. 5. With train stimulation (six impulses/20 Hz) at 0.1 Hz, each train evoked transient increases of WVPP of 1 mmHg or less in some subjects (latency around 1.6 s). After averaging weak increases were seen also after single stimuli in two subjects. Increases of stimulation current or frequency led to slowly developing sustained increases of WVPP concomitant with decreases in Skin Resistance. 6. Responses in Skin Resistance and WVPP to train stimulation at 0.1 Hz were suppressed in a dose-dependent way by I.V. injections of atropine.(ABSTRACT TRUNCATED AT 400 WORDS)
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can galvanic Skin response be used as a quantitative estimate of sympathetic nerve activity in regional anesthesia
Anesthesia & Analgesia, 1991Co-Authors: K Kirno, M Kunimoto, S Lundin, Mikael Elam, B G WallinAbstract:To study the relationship between Skin sympathetic nerve activity and changes in Skin Resistance (galvanic Skin response--GSR), efferent sympathetic and sensory nerves to the hand were blocked by an axillary nerve blockade in 15 healthy subjects. Subsequently, intraneural electrical stimuli in the median nerve distal to the axillary nerve block were used to evoke changes in Skin Resistance and in water vapor partial pressure in the sensory and sympathetically denervated hand. With increasing frequency of stimulation, Skin Resistance decreased and water vapor partial pressure increased until stimuli exceeded 10 Hz. When an additional burst of impulses was added to the background stimulation, GSR amplitude varied in a nonlinear fashion with the background frequency. Stimulation-induced GSR was completely abolished in a dose-dependent manner by systemically (intravenously) administered atropine. The results indicate that GSR depends on the preceding level of nerve traffic in the sympathetic sudomotor nerve fibers. Consequently, Skin Resistance recordings cannot be used to quantify sympathetic nerve traffic and thus do not express the completeness of sympathetic blockade in regional anesthesia.
Gregory P Brown - One of the best experts on this subject based on the ideXlab platform.
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Skin Resistance to water gain and loss has changed in cane toads rhinella marina during their australian invasion
Ecology and Evolution, 2020Co-Authors: Georgia K Kosmala, Gregory P Brown, Richard Shine, Keith A ChristianAbstract:The water-permeable Skin of amphibians renders them highly sensitive to climatic conditions, and interspecific correlations between environmental moisture levels and rates of water exchange across the Skin suggest that natural selection adapts hydroregulatory mechanisms to local challenges. How quickly can such mechanisms shift when a species encounters novel moisture regimes? Cutaneous Resistance to water loss and gain in wild-caught cane toads (Rhinella marina) from Brazil, USA (Hawai'i) and Australia exhibited strong geographic variation. Cutaneous Resistance was low in native-range (Brazilian) toads and in Hawai'ian populations (where toads were introduced in 1932) but significantly higher in toads from eastern Australia (where toads were introduced in 1935). Toads from recently invaded areas in western Australia exhibited cutaneous Resistance to water loss similar to the native-range populations, possibly because toads are restricted to moist sites within this highly arid landscape. Rates of rehydration exhibited significant but less extreme geographic variation, being higher in the native range than in invaded regions. Thus, in less than a century, cane toads invading areas that impose different climatic challenges have diverged in the capacity for hydroregulation.