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Vaughan G. Macefield - One of the best experts on this subject based on the ideXlab platform.
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Effects of deep and superficial experimentally induced acute Pain on Skin sympathetic nerve activity in human subjects.
Experimental brain research, 2009Co-Authors: Alexander R. Burton, Ingvars Birznieks, Luke A. Henderson, Jonas Spaak, Vaughan G. MacefieldAbstract:There is evidence in experimental animals that deep and superficial Pain exert differential effects on cutaneous sympathetic activity. Skin sympathetic nerve activity (SSNA) was recorded from the common peroneal nerve of awake human subjects and injections of 0.5 ml hypertonic saline was made into the tibialis anterior muscle (causing a deep, dull ache) or 0.2 ml into the overlying Skin (causing a sharp burning Pain) at unexpected times. Both deep and superficial Pain caused increases in SSNA immediately on injection and preceding the onset of Pain for both muscle and Skin Pain (10.1 ± 2.4 vs. 15.3 ± 5.3 s; muscle versus Skin, respectively). SSNA increases were short lasting (104.2 ± 13.4 vs. 81.8 ± 11.7 s; muscle versus Skin Pain) and did not follow muscle and Skin Pain profiles. Sweat release occurred following both intramuscular and subcutaneous injections of hypertonic saline. While muscle or Skin Pain invariably caused changes in Skin blood flow as well as increases in sweat release, Skin blood flow increased in females and decreased in males. We conclude that both acute muscle and Skin Pain cause an increase in SSNA, sweat release and gender-dependent changes in Skin blood flow.
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effects of deep and superficial experimentally induced acute Pain on muscle sympathetic nerve activity in human subjects
The Journal of Physiology, 2009Co-Authors: Ingvars Birznieks, Alexander R. Burton, Vaughan G. Macefield, Philip S. Bolton, Luke A. HendersonAbstract:Human studies conducted more than half a century ago have suggested that superficial Pain induces excitatory effects on the sympathetic nervous system, resulting in increases in blood pressure (BP) and heart rate (HR), whereas deep Pain is believed to cause vasodepression. To date, no studies have addressed whether deep or superficial Pain produces such differential effects on muscle sympathetic nerve activity (MSNA). Using microneurography we recorded spontaneous MSNA from the common peroneal nerve in 13 awake subjects. Continuous blood pressure was recorded by radial arterial tonometry. Deep Pain was induced by intramuscular injection of 0.5 ml hypertonic saline (5%) into the tibialis anterior muscle, superficial Pain by subcutaneous injection of 0.2 ml hypertonic saline into the overlying Skin. Muscle Pain, with a mean rating of 4.9 ± 0.8 (s.e.m.) on a 0–10 visual analog scale (VAS) and lasting on average 358 ± 32 s, caused significant increases in MSNA (43.9 ± 10.0%), BP (5.4 ± 1.1%) and HR (7.0 ± 2.0%) – not the expected decreases. Skin Pain, rated at 4.9 ± 0.6 and lasting 464 ± 54 s, also caused significant increases in MSNA (38.2 ± 12.8%), BP (5.1 ± 2.1%) and HR (5.6 ± 2.0%). The high-frequency (HF) to low-frequency (LF) ratio of heart rate variability (HRV) increased from 1.54 ± 0.25 to 2.90 ± 0.45 for muscle Pain and 2.80 ± 0.52 for Skin Pain. Despite the different qualities of deep (dull and diffuse) and superficial (burning and well-localized) Pain, we conclude that Pain originating in muscle and Skin does not exert a differential effect on muscle sympathetic nerve activity, both causing an increase in MSNA and an increase in the LF : HF ratio of HRV. Whether this holds true for longer lasting experimental Pain remains to be seen.
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Effects of deep and superficial experimentally induced acute Pain on muscle sympathetic nerve activity in human subjects
The Journal of physiology, 2008Co-Authors: Alexander R. Burton, Ingvars Birznieks, Philip S. Bolton, Luke A. Henderson, Vaughan G. MacefieldAbstract:There is evidence in experimental animals that deep and superficial Pain exert differential effects on cutaneous sympathetic activity. Skin sympathetic nerve activity (SSNA) was recorded from the common peroneal nerve of awake human subjects and injections of 0.5 ml hypertonic saline was made into the tibialis anterior muscle (causing a deep, dull ache) or 0.2 ml into the overlying Skin (causing a sharp burning Pain) at unexpected times. Both deep and superficial Pain caused increases in SSNA immediately on injection and preceding the onset of Pain for both muscle and Skin Pain (10.1 ± 2.4 vs. 15.3 ± 5.3 s; muscle versus Skin, respectively). SSNA increases were short lasting (104.2 ± 13.4 vs. 81.8 ± 11.7 s; muscle versus Skin Pain) and did not follow muscle and Skin Pain profiles. Sweat release occurred following both intramuscular and subcutaneous injections of hypertonic saline. While muscle or Skin Pain invariably caused changes in Skin blood flow as well as increases in sweat release, Skin blood flow increased in females and decreased in males. We conclude that both acute muscle and Skin Pain cause an increase in SSNA, sweat release and gender-dependent changes in Skin blood flow.
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The effects of experimental muscle and Skin Pain on the static stretch sensitivity of human muscle spindles in relaxed leg muscles
The Journal of physiology, 2008Co-Authors: Ingvars Birznieks, Alexander R. Burton, Vaughan G. MacefieldAbstract:Animal studies have shown that noxious inputs onto γ-motoneurons can cause an increase in the activity of muscle spindles, and it has been proposed that this causes a fusimotor-driven increase in muscle stiffness that is believed to underlie many chronic Pain syndromes. To test whether experimental Pain also acts on the fusimotor system in humans, unitary recordings were made from 19 spindle afferents (12 Ia, 7 II) located in the ankle and toe extensors or peronei muscles of awake human subjects. Muscle Pain was induced by bolus intramuscular injection of 0.5 ml 5% hypertonic saline into tibialis anterior (TA); Skin Pain was induced by 0.2 ml injection into the overlying Skin. Changes in fusimotor drive to the muscle spindles were inferred from changes in the mean discharge frequency and discharge variability of spindle endings in relaxed muscle. During muscle Pain no afferents increased their discharge activity: seven afferents (5 Ia, 2 II) showed a decrease and six (4 Ia, 2 II) afferents were not affected. During Skin Pain of 13 afferents discharge rate increased in one (Ia) and decreased in two (1 Ia, 1 II). On average, the overall discharge rate decreased during muscle Pain by 6.1% (P 0.05; Wilcoxon). We conclude that, contrary to the ‘vicious cycle’ hypothesis, acute activation of muscle or Skin nociceptors does not cause a reflex increase in fusimotor drive in humans. Rather, our results are more aligned with the Pain adaptation model, based on clinical studies predicting Pain-induced reductions of agonist muscle activity.
Astrid Klopstad Wahl - One of the best experts on this subject based on the ideXlab platform.
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The complex experience of psoriasis related Skin Pain: a qualitative study.
Scandinavian journal of pain, 2020Co-Authors: Tone Marte Ljosaa, Hilde Bondevik, Jon Anders Halvorsen, E Carr, Astrid Klopstad WahlAbstract:Background and aims Psoriasis is a common chronic Skin condition, causing Skin lesions with thickened and scaling Skin, as well as erythema and inflammation that may involve Painful sores, cracks, and pustules. Previously psoriasis was regarded as a Painless Skin condition. However, over the past decade studies show that Skin Pain is a frequently reported and bothersome symptom in patients with psoriasis. There is however a lack of rich narratives describing the experience of Skin Pain in these patients. The aims of this qualitative study were therefore to explore in depth how patients experience psoriasis-related Skin Pain, and how they deal with it. Methods Thirteen patients with psoriasis were recruited from a dermatology ward and outpatient clinic. One of the investigators (TML) performed individual, semi-structured interviews at an undisturbed room in the hospital. Interviews were thematically analyzed using the method of Systematic Text Condensation as described by Malterud (2012). Results Three main themes were identified from the interviews. First, the Skin Pain experience was complex. Patients used a variety of adjectives and metaphors to describe their Pain, and their Skin was sensitive to stimuli of every-day activities. Itch was a common cosymptom, and could both mask Pain but also cause severe Pain due to excessive scratching and damage to the Skin. Second, Skin Pain had a negative impact on patients' life. Skin Pain reduced their physical activity level, impaired their sleep, and made them irritable, depressed, unconcentrated on tasks, as well as withdrawn from other people and social activities. Third, patients dealt with their Skin Pain in various ways. Although some took action to relieve the Pain and distract themselves from Pain, most of the patients applied maladaptive and passive coping strategies such as put up with it, avoid Painful activities, become fearful or trivialize their Pain. Conclusions The experience of psoriasis related Skin Pain is complex. The Pain has a major negative impact on patients' life in terms of physical, emotional, cognitive, and social functions. Patients use a variety of adaptive but most frequently maladaptive coping strategies in order to deal with their Skin Pain. Implications This study provides new and in-depth knowledge on psoriasis related Skin Pain. This information is valuable for further work on Pain assessment tools and Pain management recommendations customized for Skin Pain experienced by patients with psoriasis.
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Improvement in Psoriasis Area and Severity Index score predicts improvement in Skin Pain over time in patients with psoriasis.
Acta dermato-venereologica, 2013Co-Authors: Tone Marte Ljoså, Audun Stubhaug, Cato Mørk, Torbjørn Moum, Astrid Klopstad WahlAbstract:Pain and discomfort are common and often severe Skin symptoms in patients with psoriasis. However, no studies have investigated Skin Pain and discomfort over time, or factors that explain changes in these symptoms. The aims of the present study were to describe the changes in Skin Pain, Skin discomfort and Psoriasis Area and Severity Index (PASI) over time, and to investigate whether change in PASI predicted change in Skin Pain intensity. A total of 129 patients participated in this exploratory, longitudinal study. Data were obtained through interviews and questionnaires. The results indicated reduction in Skin symptoms and psoriasis severity over a period of 3 months. However, a majority of patients with Skin Pain at baseline reported also Skin Pain at follow-up. Furthermore, changes in PASI predicted changes in Skin Pain intensity. In conclusion, improvement in psoriasis severity predicts improvement in Skin Pain.
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Skin Pain and Skin discomfort is associated with quality of life in patients with psoriasis
Journal of The European Academy of Dermatology and Venereology, 2012Co-Authors: T M Ljosaa, Cato Mørk, Audun Stubhaug, Torbjørn Moum, Astrid Klopstad WahlAbstract:Background Patients with psoriasis commonly report severe sensory Skin symptoms, sleep disturbance, psychological distress and impaired health related quality of life (HRQoL). However, the complex associations among these factors are poorly investigated in this patient group. Objectives The purpose of this study was to investigate the association between Skin Pain or Skin discomfort and HRQoL, and explore whether sleep disturbance and psychological distress were mediators of these associations. Methods A total of 139 psoriasis patients from a university hospital setting participated in this exploratory, cross-sectional study. Data were obtained through interviews and questionnaires (Dermatology Life Quality Index, General Sleep Disturbance Scale, Illness Perception Questionnaire) and analysed using a series of multiple regression analyses. HRQoL was the dependent variable. Independent variables and assumed mediators were entered into the model in a predefined order. Results Skin Pain, Skin discomfort, sleep disturbance and psychological distress were significantly associated with HRQoL (all P < 0.05). Sleep disturbance was a partial mediator for the association between Skin Pain and HRQoL. No such mediation effect was found in terms of psychological distress. The total model explained 40% of the variance in HRQoL. Conclusion In this study, Skin Pain and Skin discomfort were significantly related to HRQoL when controlling for demographic and clinical characteristics. In addition, sleep disturbance mediated the association between Skin Pain and HRQoL. An understanding of the complex association among physiological and psychological factors, and HRQoL is clinically important in order to provide proper treatment and care of patients with psoriasis.
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Skin Pain and Skin discomfort is associated with quality of life in patients with psoriasis
Journal of the European Academy of Dermatology and Venereology : JEADV, 2011Co-Authors: T M Ljosaa, Cato Mørk, Audun Stubhaug, Torbjørn Moum, Astrid Klopstad WahlAbstract:Background Patients with psoriasis commonly report severe sensory Skin symptoms, sleep disturbance, psychological distress and impaired health related quality of life (HRQoL). However, the complex associations among these factors are poorly investigated in this patient group. Objectives The purpose of this study was to investigate the association between Skin Pain or Skin discomfort and HRQoL, and explore whether sleep disturbance and psychological distress were mediators of these associations. Methods A total of 139 psoriasis patients from a university hospital setting participated in this exploratory, cross-sectional study. Data were obtained through interviews and questionnaires (Dermatology Life Quality Index, General Sleep Disturbance Scale, Illness Perception Questionnaire) and analysed using a series of multiple regression analyses. HRQoL was the dependent variable. Independent variables and assumed mediators were entered into the model in a predefined order. Results Skin Pain, Skin discomfort, sleep disturbance and psychological distress were significantly associated with HRQoL (all P
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Skin Pain and discomfort in psoriasis: an exploratory study of symptom prevalence and characteristics.
Acta dermato-venereologica, 2010Co-Authors: Tone Marte Ljosaa, Audun Stubhaug, Cato Mørk, Tone Rustøen, Christine Miaskowski, Steven M. Paul, Astrid Klopstad WahlAbstract:Few studies have investigated subjective sensory Skin symptoms in patients with psoriasis. The aim of this study was to investigate prevalence and characteristics of psoriasis-related Skin Pain and discomfort, and evaluate differences in demographic/clinical characteristics among patients with or without Skin symptoms. A total of 139 patients was recruited for this exploratory, descriptive, cross-sectional study. Data were obtained through interviews and questionnaires. While 42.6% reported Skin Pain, 36.7% reported Skin discomfort. Mean average symptom intensity score (0-10 numeric rating scale) was 4.4 for Pain and 3.5 for discomfort. Unpleasant, surface, sensitive, itchy, and hot/burning were the most common symptom qualities. Sleep was the most severely affected function. No differences were found in demographic characteristics. However, larger proportions of patients with Skin symptoms had more severe psoriasis (p < 0.05). In conclusion, Pain and discomfort are more common and more severe in patients with psoriasis than previously estimated.
Alexander R. Burton - One of the best experts on this subject based on the ideXlab platform.
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Effects of deep and superficial experimentally induced acute Pain on Skin sympathetic nerve activity in human subjects.
Experimental brain research, 2009Co-Authors: Alexander R. Burton, Ingvars Birznieks, Luke A. Henderson, Jonas Spaak, Vaughan G. MacefieldAbstract:There is evidence in experimental animals that deep and superficial Pain exert differential effects on cutaneous sympathetic activity. Skin sympathetic nerve activity (SSNA) was recorded from the common peroneal nerve of awake human subjects and injections of 0.5 ml hypertonic saline was made into the tibialis anterior muscle (causing a deep, dull ache) or 0.2 ml into the overlying Skin (causing a sharp burning Pain) at unexpected times. Both deep and superficial Pain caused increases in SSNA immediately on injection and preceding the onset of Pain for both muscle and Skin Pain (10.1 ± 2.4 vs. 15.3 ± 5.3 s; muscle versus Skin, respectively). SSNA increases were short lasting (104.2 ± 13.4 vs. 81.8 ± 11.7 s; muscle versus Skin Pain) and did not follow muscle and Skin Pain profiles. Sweat release occurred following both intramuscular and subcutaneous injections of hypertonic saline. While muscle or Skin Pain invariably caused changes in Skin blood flow as well as increases in sweat release, Skin blood flow increased in females and decreased in males. We conclude that both acute muscle and Skin Pain cause an increase in SSNA, sweat release and gender-dependent changes in Skin blood flow.
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effects of deep and superficial experimentally induced acute Pain on muscle sympathetic nerve activity in human subjects
The Journal of Physiology, 2009Co-Authors: Ingvars Birznieks, Alexander R. Burton, Vaughan G. Macefield, Philip S. Bolton, Luke A. HendersonAbstract:Human studies conducted more than half a century ago have suggested that superficial Pain induces excitatory effects on the sympathetic nervous system, resulting in increases in blood pressure (BP) and heart rate (HR), whereas deep Pain is believed to cause vasodepression. To date, no studies have addressed whether deep or superficial Pain produces such differential effects on muscle sympathetic nerve activity (MSNA). Using microneurography we recorded spontaneous MSNA from the common peroneal nerve in 13 awake subjects. Continuous blood pressure was recorded by radial arterial tonometry. Deep Pain was induced by intramuscular injection of 0.5 ml hypertonic saline (5%) into the tibialis anterior muscle, superficial Pain by subcutaneous injection of 0.2 ml hypertonic saline into the overlying Skin. Muscle Pain, with a mean rating of 4.9 ± 0.8 (s.e.m.) on a 0–10 visual analog scale (VAS) and lasting on average 358 ± 32 s, caused significant increases in MSNA (43.9 ± 10.0%), BP (5.4 ± 1.1%) and HR (7.0 ± 2.0%) – not the expected decreases. Skin Pain, rated at 4.9 ± 0.6 and lasting 464 ± 54 s, also caused significant increases in MSNA (38.2 ± 12.8%), BP (5.1 ± 2.1%) and HR (5.6 ± 2.0%). The high-frequency (HF) to low-frequency (LF) ratio of heart rate variability (HRV) increased from 1.54 ± 0.25 to 2.90 ± 0.45 for muscle Pain and 2.80 ± 0.52 for Skin Pain. Despite the different qualities of deep (dull and diffuse) and superficial (burning and well-localized) Pain, we conclude that Pain originating in muscle and Skin does not exert a differential effect on muscle sympathetic nerve activity, both causing an increase in MSNA and an increase in the LF : HF ratio of HRV. Whether this holds true for longer lasting experimental Pain remains to be seen.
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Effects of deep and superficial experimentally induced acute Pain on muscle sympathetic nerve activity in human subjects
The Journal of physiology, 2008Co-Authors: Alexander R. Burton, Ingvars Birznieks, Philip S. Bolton, Luke A. Henderson, Vaughan G. MacefieldAbstract:There is evidence in experimental animals that deep and superficial Pain exert differential effects on cutaneous sympathetic activity. Skin sympathetic nerve activity (SSNA) was recorded from the common peroneal nerve of awake human subjects and injections of 0.5 ml hypertonic saline was made into the tibialis anterior muscle (causing a deep, dull ache) or 0.2 ml into the overlying Skin (causing a sharp burning Pain) at unexpected times. Both deep and superficial Pain caused increases in SSNA immediately on injection and preceding the onset of Pain for both muscle and Skin Pain (10.1 ± 2.4 vs. 15.3 ± 5.3 s; muscle versus Skin, respectively). SSNA increases were short lasting (104.2 ± 13.4 vs. 81.8 ± 11.7 s; muscle versus Skin Pain) and did not follow muscle and Skin Pain profiles. Sweat release occurred following both intramuscular and subcutaneous injections of hypertonic saline. While muscle or Skin Pain invariably caused changes in Skin blood flow as well as increases in sweat release, Skin blood flow increased in females and decreased in males. We conclude that both acute muscle and Skin Pain cause an increase in SSNA, sweat release and gender-dependent changes in Skin blood flow.
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The effects of experimental muscle and Skin Pain on the static stretch sensitivity of human muscle spindles in relaxed leg muscles
The Journal of physiology, 2008Co-Authors: Ingvars Birznieks, Alexander R. Burton, Vaughan G. MacefieldAbstract:Animal studies have shown that noxious inputs onto γ-motoneurons can cause an increase in the activity of muscle spindles, and it has been proposed that this causes a fusimotor-driven increase in muscle stiffness that is believed to underlie many chronic Pain syndromes. To test whether experimental Pain also acts on the fusimotor system in humans, unitary recordings were made from 19 spindle afferents (12 Ia, 7 II) located in the ankle and toe extensors or peronei muscles of awake human subjects. Muscle Pain was induced by bolus intramuscular injection of 0.5 ml 5% hypertonic saline into tibialis anterior (TA); Skin Pain was induced by 0.2 ml injection into the overlying Skin. Changes in fusimotor drive to the muscle spindles were inferred from changes in the mean discharge frequency and discharge variability of spindle endings in relaxed muscle. During muscle Pain no afferents increased their discharge activity: seven afferents (5 Ia, 2 II) showed a decrease and six (4 Ia, 2 II) afferents were not affected. During Skin Pain of 13 afferents discharge rate increased in one (Ia) and decreased in two (1 Ia, 1 II). On average, the overall discharge rate decreased during muscle Pain by 6.1% (P 0.05; Wilcoxon). We conclude that, contrary to the ‘vicious cycle’ hypothesis, acute activation of muscle or Skin nociceptors does not cause a reflex increase in fusimotor drive in humans. Rather, our results are more aligned with the Pain adaptation model, based on clinical studies predicting Pain-induced reductions of agonist muscle activity.
Ingvars Birznieks - One of the best experts on this subject based on the ideXlab platform.
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Effects of deep and superficial experimentally induced acute Pain on Skin sympathetic nerve activity in human subjects.
Experimental brain research, 2009Co-Authors: Alexander R. Burton, Ingvars Birznieks, Luke A. Henderson, Jonas Spaak, Vaughan G. MacefieldAbstract:There is evidence in experimental animals that deep and superficial Pain exert differential effects on cutaneous sympathetic activity. Skin sympathetic nerve activity (SSNA) was recorded from the common peroneal nerve of awake human subjects and injections of 0.5 ml hypertonic saline was made into the tibialis anterior muscle (causing a deep, dull ache) or 0.2 ml into the overlying Skin (causing a sharp burning Pain) at unexpected times. Both deep and superficial Pain caused increases in SSNA immediately on injection and preceding the onset of Pain for both muscle and Skin Pain (10.1 ± 2.4 vs. 15.3 ± 5.3 s; muscle versus Skin, respectively). SSNA increases were short lasting (104.2 ± 13.4 vs. 81.8 ± 11.7 s; muscle versus Skin Pain) and did not follow muscle and Skin Pain profiles. Sweat release occurred following both intramuscular and subcutaneous injections of hypertonic saline. While muscle or Skin Pain invariably caused changes in Skin blood flow as well as increases in sweat release, Skin blood flow increased in females and decreased in males. We conclude that both acute muscle and Skin Pain cause an increase in SSNA, sweat release and gender-dependent changes in Skin blood flow.
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effects of deep and superficial experimentally induced acute Pain on muscle sympathetic nerve activity in human subjects
The Journal of Physiology, 2009Co-Authors: Ingvars Birznieks, Alexander R. Burton, Vaughan G. Macefield, Philip S. Bolton, Luke A. HendersonAbstract:Human studies conducted more than half a century ago have suggested that superficial Pain induces excitatory effects on the sympathetic nervous system, resulting in increases in blood pressure (BP) and heart rate (HR), whereas deep Pain is believed to cause vasodepression. To date, no studies have addressed whether deep or superficial Pain produces such differential effects on muscle sympathetic nerve activity (MSNA). Using microneurography we recorded spontaneous MSNA from the common peroneal nerve in 13 awake subjects. Continuous blood pressure was recorded by radial arterial tonometry. Deep Pain was induced by intramuscular injection of 0.5 ml hypertonic saline (5%) into the tibialis anterior muscle, superficial Pain by subcutaneous injection of 0.2 ml hypertonic saline into the overlying Skin. Muscle Pain, with a mean rating of 4.9 ± 0.8 (s.e.m.) on a 0–10 visual analog scale (VAS) and lasting on average 358 ± 32 s, caused significant increases in MSNA (43.9 ± 10.0%), BP (5.4 ± 1.1%) and HR (7.0 ± 2.0%) – not the expected decreases. Skin Pain, rated at 4.9 ± 0.6 and lasting 464 ± 54 s, also caused significant increases in MSNA (38.2 ± 12.8%), BP (5.1 ± 2.1%) and HR (5.6 ± 2.0%). The high-frequency (HF) to low-frequency (LF) ratio of heart rate variability (HRV) increased from 1.54 ± 0.25 to 2.90 ± 0.45 for muscle Pain and 2.80 ± 0.52 for Skin Pain. Despite the different qualities of deep (dull and diffuse) and superficial (burning and well-localized) Pain, we conclude that Pain originating in muscle and Skin does not exert a differential effect on muscle sympathetic nerve activity, both causing an increase in MSNA and an increase in the LF : HF ratio of HRV. Whether this holds true for longer lasting experimental Pain remains to be seen.
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Effects of deep and superficial experimentally induced acute Pain on muscle sympathetic nerve activity in human subjects
The Journal of physiology, 2008Co-Authors: Alexander R. Burton, Ingvars Birznieks, Philip S. Bolton, Luke A. Henderson, Vaughan G. MacefieldAbstract:There is evidence in experimental animals that deep and superficial Pain exert differential effects on cutaneous sympathetic activity. Skin sympathetic nerve activity (SSNA) was recorded from the common peroneal nerve of awake human subjects and injections of 0.5 ml hypertonic saline was made into the tibialis anterior muscle (causing a deep, dull ache) or 0.2 ml into the overlying Skin (causing a sharp burning Pain) at unexpected times. Both deep and superficial Pain caused increases in SSNA immediately on injection and preceding the onset of Pain for both muscle and Skin Pain (10.1 ± 2.4 vs. 15.3 ± 5.3 s; muscle versus Skin, respectively). SSNA increases were short lasting (104.2 ± 13.4 vs. 81.8 ± 11.7 s; muscle versus Skin Pain) and did not follow muscle and Skin Pain profiles. Sweat release occurred following both intramuscular and subcutaneous injections of hypertonic saline. While muscle or Skin Pain invariably caused changes in Skin blood flow as well as increases in sweat release, Skin blood flow increased in females and decreased in males. We conclude that both acute muscle and Skin Pain cause an increase in SSNA, sweat release and gender-dependent changes in Skin blood flow.
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The effects of experimental muscle and Skin Pain on the static stretch sensitivity of human muscle spindles in relaxed leg muscles
The Journal of physiology, 2008Co-Authors: Ingvars Birznieks, Alexander R. Burton, Vaughan G. MacefieldAbstract:Animal studies have shown that noxious inputs onto γ-motoneurons can cause an increase in the activity of muscle spindles, and it has been proposed that this causes a fusimotor-driven increase in muscle stiffness that is believed to underlie many chronic Pain syndromes. To test whether experimental Pain also acts on the fusimotor system in humans, unitary recordings were made from 19 spindle afferents (12 Ia, 7 II) located in the ankle and toe extensors or peronei muscles of awake human subjects. Muscle Pain was induced by bolus intramuscular injection of 0.5 ml 5% hypertonic saline into tibialis anterior (TA); Skin Pain was induced by 0.2 ml injection into the overlying Skin. Changes in fusimotor drive to the muscle spindles were inferred from changes in the mean discharge frequency and discharge variability of spindle endings in relaxed muscle. During muscle Pain no afferents increased their discharge activity: seven afferents (5 Ia, 2 II) showed a decrease and six (4 Ia, 2 II) afferents were not affected. During Skin Pain of 13 afferents discharge rate increased in one (Ia) and decreased in two (1 Ia, 1 II). On average, the overall discharge rate decreased during muscle Pain by 6.1% (P 0.05; Wilcoxon). We conclude that, contrary to the ‘vicious cycle’ hypothesis, acute activation of muscle or Skin nociceptors does not cause a reflex increase in fusimotor drive in humans. Rather, our results are more aligned with the Pain adaptation model, based on clinical studies predicting Pain-induced reductions of agonist muscle activity.
Luke A. Henderson - One of the best experts on this subject based on the ideXlab platform.
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Effects of deep and superficial experimentally induced acute Pain on Skin sympathetic nerve activity in human subjects.
Experimental brain research, 2009Co-Authors: Alexander R. Burton, Ingvars Birznieks, Luke A. Henderson, Jonas Spaak, Vaughan G. MacefieldAbstract:There is evidence in experimental animals that deep and superficial Pain exert differential effects on cutaneous sympathetic activity. Skin sympathetic nerve activity (SSNA) was recorded from the common peroneal nerve of awake human subjects and injections of 0.5 ml hypertonic saline was made into the tibialis anterior muscle (causing a deep, dull ache) or 0.2 ml into the overlying Skin (causing a sharp burning Pain) at unexpected times. Both deep and superficial Pain caused increases in SSNA immediately on injection and preceding the onset of Pain for both muscle and Skin Pain (10.1 ± 2.4 vs. 15.3 ± 5.3 s; muscle versus Skin, respectively). SSNA increases were short lasting (104.2 ± 13.4 vs. 81.8 ± 11.7 s; muscle versus Skin Pain) and did not follow muscle and Skin Pain profiles. Sweat release occurred following both intramuscular and subcutaneous injections of hypertonic saline. While muscle or Skin Pain invariably caused changes in Skin blood flow as well as increases in sweat release, Skin blood flow increased in females and decreased in males. We conclude that both acute muscle and Skin Pain cause an increase in SSNA, sweat release and gender-dependent changes in Skin blood flow.
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effects of deep and superficial experimentally induced acute Pain on muscle sympathetic nerve activity in human subjects
The Journal of Physiology, 2009Co-Authors: Ingvars Birznieks, Alexander R. Burton, Vaughan G. Macefield, Philip S. Bolton, Luke A. HendersonAbstract:Human studies conducted more than half a century ago have suggested that superficial Pain induces excitatory effects on the sympathetic nervous system, resulting in increases in blood pressure (BP) and heart rate (HR), whereas deep Pain is believed to cause vasodepression. To date, no studies have addressed whether deep or superficial Pain produces such differential effects on muscle sympathetic nerve activity (MSNA). Using microneurography we recorded spontaneous MSNA from the common peroneal nerve in 13 awake subjects. Continuous blood pressure was recorded by radial arterial tonometry. Deep Pain was induced by intramuscular injection of 0.5 ml hypertonic saline (5%) into the tibialis anterior muscle, superficial Pain by subcutaneous injection of 0.2 ml hypertonic saline into the overlying Skin. Muscle Pain, with a mean rating of 4.9 ± 0.8 (s.e.m.) on a 0–10 visual analog scale (VAS) and lasting on average 358 ± 32 s, caused significant increases in MSNA (43.9 ± 10.0%), BP (5.4 ± 1.1%) and HR (7.0 ± 2.0%) – not the expected decreases. Skin Pain, rated at 4.9 ± 0.6 and lasting 464 ± 54 s, also caused significant increases in MSNA (38.2 ± 12.8%), BP (5.1 ± 2.1%) and HR (5.6 ± 2.0%). The high-frequency (HF) to low-frequency (LF) ratio of heart rate variability (HRV) increased from 1.54 ± 0.25 to 2.90 ± 0.45 for muscle Pain and 2.80 ± 0.52 for Skin Pain. Despite the different qualities of deep (dull and diffuse) and superficial (burning and well-localized) Pain, we conclude that Pain originating in muscle and Skin does not exert a differential effect on muscle sympathetic nerve activity, both causing an increase in MSNA and an increase in the LF : HF ratio of HRV. Whether this holds true for longer lasting experimental Pain remains to be seen.
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Effects of deep and superficial experimentally induced acute Pain on muscle sympathetic nerve activity in human subjects
The Journal of physiology, 2008Co-Authors: Alexander R. Burton, Ingvars Birznieks, Philip S. Bolton, Luke A. Henderson, Vaughan G. MacefieldAbstract:There is evidence in experimental animals that deep and superficial Pain exert differential effects on cutaneous sympathetic activity. Skin sympathetic nerve activity (SSNA) was recorded from the common peroneal nerve of awake human subjects and injections of 0.5 ml hypertonic saline was made into the tibialis anterior muscle (causing a deep, dull ache) or 0.2 ml into the overlying Skin (causing a sharp burning Pain) at unexpected times. Both deep and superficial Pain caused increases in SSNA immediately on injection and preceding the onset of Pain for both muscle and Skin Pain (10.1 ± 2.4 vs. 15.3 ± 5.3 s; muscle versus Skin, respectively). SSNA increases were short lasting (104.2 ± 13.4 vs. 81.8 ± 11.7 s; muscle versus Skin Pain) and did not follow muscle and Skin Pain profiles. Sweat release occurred following both intramuscular and subcutaneous injections of hypertonic saline. While muscle or Skin Pain invariably caused changes in Skin blood flow as well as increases in sweat release, Skin blood flow increased in females and decreased in males. We conclude that both acute muscle and Skin Pain cause an increase in SSNA, sweat release and gender-dependent changes in Skin blood flow.