scholarly journals Automated Nociceptive Withdrawal Reflex Measurements Reveal Normal Reflex Thresholds and Augmented Pain Ratings in Patients with Fibromyalgia

2020 ◽  
Vol 9 (6) ◽  
pp. 1992
Author(s):  
Johannes Ydrefors ◽  
Tomas Karlsson ◽  
Ulrika Wentzel Olausson ◽  
Bijar Ghafouri ◽  
Ann-Charlotte Johansson ◽  
...  
Keyword(s):  
Tibialis Anterior ◽  
Pain Sensitivity ◽  
Tibialis Anterior Muscle ◽  
Electromyographic Activity ◽  
Nociceptive Withdrawal Reflex ◽  
Withdrawal Reflex ◽  
Pain Ratings ◽  
Subjective Pain ◽  
Electrical Stimuli ◽  
Spinal Sensitization

The nociceptive withdrawal reflex (NWR) is used to probe spinal cord excitability in chronic pain states. Here, we used an automated and unbiased procedure for determining the NWR threshold and compared the reflex thresholds and corresponding pain ratings in a well-characterized cohort of fibromyalgia (n = 29) and matched healthy controls (n = 21). Surface electrical stimuli were delivered to the foot in a stepwise incremental and decremental manner. The surface electromyographic activity was recorded from the ipsilateral tibialis anterior muscle. Fibromyalgia patients reported significantly higher scores for psychological distress and pain-related disability and a significantly lower score for perceived state of health compared to the matched controls. The subjective pain ratings were significantly higher in patients. The NWR thresholds were similar to the controls. In the patients, but not in controls, the NWR thresholds and subjective pain ratings were significantly correlated. Our results showed an increased subjective pain sensitivity in fibromyalgia, but we found no evidence for spinal sensitization based on the reflex measures.

Pain sensitivity changes in chronic pain patients with and without spinal cord stimulation assessed by nociceptive withdrawal reflex thresholds and electrical pain thresholds

2012 ◽  
Vol 3 (3) ◽  
pp. 183-183
Author(s):  
J.A. Biurrun Manresa ◽  
J. Sörensen ◽  
A.-C. Sandell ◽  
O.K. Andersen ◽  
L. Arendt-Nielsen ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Chronic Pain ◽  
Pain Sensitivity ◽  
Tibialis Anterior Muscle ◽  
Pain Thresholds ◽  
Nociceptive Withdrawal Reflex ◽  
Withdrawal Reflex ◽  
Before And After ◽  
Scale Range ◽  
Sensitivity Changes

Abstract Background and aim Previous studies have shown that patients with chronic pain had significantly lower nociceptive withdrawal reflex thresholds (NWR-T) and electrical pain thresholds (EP-T) than healthy controls. Patients with chronic pain and implanted spinal cord stimulator (SCS) system presents an opportunity to study dynamic pain sensitivity changes in a situation where patients just have been stimulated (i.e., pain-free or greatly reduced pain) and compare with the situation where patients are not stimulated (i.e., experiencing severe pain). Methods Seventeen volunteers with chronic neuropathic pain and a SCS implanted for pain relief participated in the experiment. Volunteers were asked to turn off the SCS and refrain from medication at least 8 h before the experiment. Electrical stimulation (train-of-five 1-ms pulses delivered at 200 Hz) was applied to the arc of the foot in order to elicit the NWR and electromyographic responses were recorded from tibialis anterior muscle. A staircase procedure was used to assess the NWR-T and a Visual-Analog-Scale (VAS) scale (range 0–10) was used to assess the EP-T. After the initial testing, the SCS was turned on, and thresholds were reassessed after 1 h. Paired t-tests were used to compare the thresholds before and after the SCS was turned on. All values are presented as mean ± SD. Results The NWR-T were significantly higher after the SCS was turned on (before: 16.3 ±8.1 mA; after: 19.0 ± 10.9 mA; p = 0.028). EP-T did not show any significant differences (before: 3.2 ± 1.5 mA; after: 2.9 ± 2.0 mA; p = 0.324). Conclusion Results showed a higher NWR-T after the SCS was turned on, which indicates a depression of spinal nociception. Moreover, the NWR-T was able to detect ongoing and relatively quick changes in pain sensitivity.

scholarly journals Increased deep pain sensitivity in persistent musculoskeletal pain but not in other musculoskeletal pain states

2016 ◽  
Vol 13 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Helena Eva Margareta Gunnarsson ◽  
Birgitta Grahn ◽  
Jens Agerström
Keyword(s):  
Musculoskeletal Pain ◽  
Acute Pain ◽  
Tibialis Anterior ◽  
Pain Sensitivity ◽  
Tibialis Anterior Muscle ◽  
Persistent Pain ◽  
Healthy Controls ◽  
Recurrent Pain ◽  
Pressure Pain Thresholds ◽  
Pain Duration

AbstractBackgroundPressure pain thresholds (PPTs) in a non-painful body area are known to be affected in some chronic pain states. The aim of this study is to investigate PPTs in a pain-free body part in relation to pain persistence and intensity in patients with musculoskeletal pain.MethodsPatients with musculoskeletal pain were divided into three different pain groups: acute pain (pain duration < 3 months, n = 38), regularly recurrent pain (regularly recurrent pain duration > 3 months, n = 56), persistent pain (persistent pain duration >3 months, n = 52) and a healthy control group (n = 51). PPT measures were conducted over the tibialis anterior muscle on the right leg in all groups.ResultsThe persistent pain group showed significantly lower PPTs over the tibialis anterior muscle compared to controls. No significant differences were found between the acute and regularly recurrent pain groups compared to healthy controls. Significant correlations, albeit small, were found between pain intensity and PPTs.ConclusionsIncreased deep pain sensitivity was found in patients with persistent musculoskeletal pain, but not in regularly recurrent pain or in acute pain. Yet, a limitation of the study is that it did not have sufficient power to detect small levels of increased deep pain sensitivity among the latter groups when compared to healthy controls.ImplicationsKnowledge about increased general hypersensitivity in persistent musculoskeletal pain could be important in clinical treatment.

scholarly journals Activity of the Tibialis Anterior Muscle Associated with the Paw Withdrawal Reflex can be Considered as an Indicator for Estimating Chronic Muscle Pain

2009 ◽  
Vol 29 (2) ◽  
pp. 115-118
Author(s):  
Junichiro TAMAKI ◽  
Masayoshi TSURUOKA ◽  
Dan WANG ◽  
Masako MAEDA ◽  
Bunsho HAYASHI ◽  
...  
Keyword(s):  
Muscle Pain ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Withdrawal Reflex ◽  
Chronic Muscle Pain

Aerobic Exercise Reduces Pressure More Than Heat Pain Sensitivity in Healthy Adults

Pain Medicine ◽  
2019 ◽  
Vol 20 (8) ◽  
pp. 1534-1546 ◽  
Author(s):  
Matthew D Jones ◽  
James L Nuzzo ◽  
Janet L Taylor ◽  
Benjamin K Barry
Keyword(s):  
Evoked Potentials ◽  
Aerobic Exercise ◽  
Tibialis Anterior ◽  
Pain Sensitivity ◽  
Healthy Adults ◽  
Heat Pain ◽  
Laser Evoked Potentials ◽  
Pain Thresholds ◽  
Pain Ratings ◽  
Exercise Induced

Abstract Objectives The hypoalgesic effects of exercise are well described, but there are conflicting findings for different modalities of pain; in particular for mechanical vs thermal noxious stimuli, which are the most commonly used in studies of exercise-induced hypoalgesia. The aims of this study were 1) to investigate the effect of aerobic exercise on pressure and heat pain thresholds that were well equated with regard to their temporal and spatial profile and 2) to identify whether changes in the excitability of nociceptive pathways—measured using laser-evoked potentials—accompany exercise-induced hypoalgesia. Subjects Sixteen healthy adults recruited from the University of New South Wales. Methods Pressure and heat pain thresholds and pain ratings to laser stimulation and laser-evoked potentials were measured before and after aerobic cycling exercise and an equivalent period of light activity. Results Pressure pain thresholds increased substantially after exercise (rectus femoris: 29.6%, d = 0.82, P < 0.001; tibialis anterior: 26.9%, d = 0.61, P < 0.001), whereas heat pain thresholds did not (tibialis anterior: 4.2%, d = 0.30, P = 0.27; foot: 0.44%, d = 0.02, P = 1). Laser-evoked potentials and laser heat pain ratings also changed minimally after exercise (d = −0.59 to 0.3, P > 0.06). Conclusions This is the first investigation to compare the effects of exercise on pressure and heat pain using the same stimulation site and pattern. The results show that aerobic exercise reduces mechanical pain sensitivity more than thermal pain sensitivity.

Investigating mechanisms behind offset analgesia: Effect on spinal responses during thermal stimulation

2014 ◽  
Vol 5 (3) ◽  
pp. 207-208
Author(s):  
Thomas Kronborg Larsen ◽  
Andreas Egmose ◽  
Marianne Enggaard ◽  
Rósa Hugosdóttir ◽  
Federico Arguissain ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Tibialis Anterior Muscle ◽  
Noxious Heat ◽  
Baseline Trial ◽  
Nociceptive Neurons ◽  
Pain Ratings ◽  
Subjective Pain ◽  
Wdr Neurons ◽  
Perceptual Mechanism ◽  
Stimulation Of

AbstractIntroductionOffset analgesia (OA) is a temporal perceptual mechanism in which subjective pain ratings decrease disproportionally when a noxious heat stimulus is decreased by 1–3 ◦C. Whether OA is a peripheral, spinal or supraspinal mechanism remains unknown. The stimulation of afferent nociceptors in the foot, leads to a spinal nociceptive withdrawal reflex (NWR) which is mediated through the wide dynamic range (WDR) neurons and therefore under descending control. We hypothesized that OA affects the spinal nociceptive neurons resulting in an attenuation of the NWR during OA.MethodsFour heat stimulations profiles were applied to the lower legs divided into four segments of 5 s, 5 s, 5 s, and 15 s, respectively: Offset Analgesia Trial (OAT) (48, 49, 48, 48 ◦C), Offset Baseline Trial (OBT) (48, 49, 32, 32 ◦C), Constant Heat Trial (CHT) (4 × 48 ◦C), and Baseline Trial (BT) (4 × 32 ◦C). Subjects rated the pain intensity continuously using a visual analog scale (VAS). NWR were evoked by electrical stimulation of the plantar foot and assessed once during each segment by recording EMG from the tibialis anterior muscle.ResultsVAS-ratings were lower during the third period of OAT compared to CHT (p < 0.001). However, there was no difference (p > 0.05) comparing the NWR size between OAT, OBT, CHT, and BT throughout the time periods.ConclusionsThe NWR was not affected by OA suggesting that spinal WDR plays a limited role in the OA mechanism. Whether peripheral- or supraspinal mechanisms are responsible the OA phenomenon remains unknown.

scholarly journals Neural indicators of perceptual variability of pain across species

2019 ◽  
Vol 116 (5) ◽  
pp. 1782-1791 ◽  
Author(s):  
L. Hu ◽  
G. D. Iannetti
Keyword(s):  
Pain Sensitivity ◽  
Pain Perception ◽  
Gamma Band ◽  
Neural Responses ◽  
Neural Activities ◽  
Nociceptive Stimulus ◽  
Pain Ratings ◽  
Subjective Pain ◽  
Perceptual Variability ◽  
The Relationship

Individuals exhibit considerable and unpredictable variability in painful percepts in response to the same nociceptive stimulus. Previous work has found neural responses that, while not necessarily responsible for the painful percepts themselves, can still correlate well with intensity of pain perception within a given individual. However, there is no reliable neural response reflecting the variability in pain perception across individuals. Here, we use an electrophysiological approach in humans and rodents to demonstrate that brain oscillations in the gamma band [gamma-band event-related synchronization (γ-ERS)] sampled by central electrodes reliably predict pain sensitivity across individuals. We observed a clear dissociation between the large number of neural measures that reflected subjective pain ratings at within-subject level but not across individuals, and γ-ERS, which reliably distinguished subjective ratings within the same individual but also coded pain sensitivity across different individuals. Importantly, the ability of γ-ERS to track pain sensitivity across individuals was selective because it did not track the between-subject reported intensity of nonpainful but equally salient auditory, visual, and nonnociceptive somatosensory stimuli. These results also demonstrate that graded neural activity related to within-subject variability should be minimized to accurately investigate the relationship between nociceptive-evoked neural activities and pain sensitivity across individuals.

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