scholarly journals Sterile water; a novel and promising human experimental muscle pain model

2020 ◽  
Author(s):  
Sofia Louca Jounger ◽  
Johanna Svedenlöf ◽  
Reija Elenius ◽  
Christoffer Källkrans ◽  
Emil Scheid ◽  
...  
Keyword(s):  
Pain Intensity ◽  
Hypertonic Saline ◽  
Intramuscular Injection ◽  
Isotonic Saline ◽  
Controlled Study ◽  
Sterile Water ◽  
Pain Model ◽  
Pain Drawing ◽  
Pressure Pain Thresholds ◽  
Pain Duration

Abstract Background Intramuscular injection of hypertonic saline evokes pain with similar characteristics as clinical myalgia and is thus, considered a valid human experimental model. The aim of this study was to investigate if intramuscular injection of sterile water can be used as a human experimental pain model by comparing it with hypertonic and isotonic saline, and to analyze if the effects differ between men and women. Methods This randomized double blind and placebo-controlled study included 15 healthy women and 15 healthy age-matched men (mean (SD) age of 23.6 (2.4) years). The study comprised of three separate sessions, with at least one week of wash out between each session. Sterile water (i.e. the test-substance), hypertonic saline (active control), and isotonic saline (passive control) were injected intramuscularly into one of the masseter muscles in a randomized order. Pain intensity (VAS) was assessed every 15 th s after the injection and pain duration (s) as well as pain drawing area (au) were recorded. Pressure pain thresholds (kPa) were assessed every 5 min after injection during 30 min. Results All substances evoked pain ( P < 0001), but sterile water and hypertonic saline induced pain with higher intensity ( P < 0.001), longer duration ( P < 0.001), and larger pain drawing area ( P < 0.001) than isotonic saline. The pain intensity was higher for hypertonic saline than sterile water 45-165 s after injection ( P < 0.015), but there were no significant differences between them regarding maximum pain intensity, pain duration or pain drawing area. There was no significant difference in PPT values with time or between substances. The pain duration was longer in the men compared to the women for all substances ( P < 0.006), while the pain drawing area was larger in women after injection of hypertonic saline ( P < 0.003), but not after injection of the other substances. No other sex differences were found. Conclusion Injection of sterile water had similar effects as hypertonic saline on pain variables, but no effect on PPT. Hence, the model mimics clinical myalgia and may offer a novel and simpler alternative to hypertonic saline injections.

The Relationship Between Corticomotor Reorganization and Acute Pain Severity: A Randomized, Controlled Study Using Rapid Transcranial Magnetic Stimulation Mapping

Pain Medicine ◽  
2020 ◽  
Author(s):  
Rocco Cavaleri ◽  
Lucy S Chipchase ◽  
Simon J Summers ◽  
Jane Chalmers ◽  
Siobhan M Schabrun
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Pain Intensity ◽  
Acute Pain ◽  
Symptom Severity ◽  
Magnetic Stimulation ◽  
Isotonic Saline ◽  
Point Estimation ◽  
Controlled Study ◽  
Peripheral Sensitization ◽  
Pressure Pain Thresholds

Abstract Objective Although acute pain has been shown to reduce corticomotor excitability, it remains unknown whether this response resolves over time or is related to symptom severity. Furthermore, acute pain research has relied upon data acquired from the cranial “hotspot,” which do not provide valuable information regarding reorganization, such as changes to the distribution of a painful muscle’s representation within M1. Using a novel, rapid transcranial magnetic stimulation (TMS) mapping method, this study aimed to 1) explore the temporal profile and variability of corticomotor reorganization in response to acute pain and 2) determine whether individual patterns of corticomotor reorganization are associated with differences in pain, sensitivity, and somatosensory organization. Methods Corticomotor (TMS maps), pain processing (pain intensity, pressure pain thresholds), and somatosensory (two-point discrimination, two-point estimation) outcomes were taken at baseline, immediately after injection (hypertonic [n = 20] or isotonic saline [n = 20]), and at pain resolution. Follow-up measures were recorded every 15 minutes until 90 minutes after injection. Results Corticomotor reorganization persisted at least 90 minutes after pain resolution. Corticomotor depression was associated with lower pain intensity than was corticomotor facilitation (r = 0.47 [P = 0.04]). These effects were not related to somatosensory reorganization or peripheral sensitization mechanisms. Conclusions Individual patterns of corticomotor reorganization during acute pain appear to be related to symptom severity, with early corticomotor depression possibly reflecting a protective response. These findings hold important implications for the management and potential prevention of pain chronicity. However, further research is required to determine whether these adaptations relate to long-term outcomes in clinical populations.

scholarly journals Repeated buffered acidic saline infusion in the human masseter muscle as a putative experimental pain model

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sofia Louca Jounger ◽  
Niklas Eriksson ◽  
Helena Lindskog ◽  
Anna Oscarsson ◽  
Vivian Simonsson ◽  
...  
Keyword(s):  
Pain Intensity ◽  
Muscle Pain ◽  
Saline Solution ◽  
Isotonic Saline ◽  
Mouth Opening ◽  
Saline Infusion ◽  
Controlled Study ◽  
Solution Ph ◽  
Pressure Pain Thresholds ◽  
Masseter Muscles

Abstract This study investigated if repeated buffered acidic saline infusions into the masseter muscles induced muscle pain and mechanical sensitization. Fourteen healthy men participated in this double-blind, randomized, and placebo-controlled study. Two repeated infusions (day 1 and 3) were given in the masseter muscles with either a buffered acidic saline solution (pH 5.2) or an isotonic saline solution (pH 6) as control. After 10 days of wash-out, the experiment was repeated with the other substance. Pressure pain thresholds (PPT), pain intensity, maximum unassisted mouth opening (MUO), and pain drawings were assessed before, directly following, and after each infusion at 5, 15, and 30 min and on day 4 and 7. Fatigue and pain intensity were assessed after a one-minute chewing test 30 min after infusions and day 4 and 7. Acidic saline induced higher pain intensity than control day 3 up to 5 min after infusions, but did not affect PPT. The chewing test did not evoke higher fatigue during chewing or MUO or after acidic saline infusion compared to control. Repeated acidic saline infusions in the masseter muscles induced a short-lasting muscle pain without mechanical hyperalgesia or functional pain. Hence, this model might not be superior to already existing experimental muscle pain models.

Hypoalgesia after exercises with painful vs. non-painful muscles in healthy subjects – a randomized cross-over study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Hansen ◽  
Kristian Kjær Petersen ◽  
Emilie Sloth ◽  
Line Appelon Manum ◽  
Anita Kjær McDonald ◽  
...  
Keyword(s):  
Pain Intensity ◽  
Hypertonic Saline ◽  
Rating Scales ◽  
Isotonic Saline ◽  
Thigh Muscle ◽  
Exercise Session ◽  
Pressure Pain Thresholds ◽  
Exercise Induced ◽  
The Right ◽  
Pain At Rest

Abstract Objectives Exercise-induced hypoalgesia (EIH) is a decrease in the pain sensitivity after exercise. Individuals with chronic pain show less EIH after one exercise session compared with pain-free individuals possibly due to pain in exercising muscles. The primary aim of this randomized controlled cross-over study was to compare the EIH response at the exercising thigh muscle following exercises performed with painful vs. non-painful muscles. Secondary aims were to explore if a reduced EIH response was confined to the painful muscle, and whether the muscle pain intensity and the EIH responses were negatively associated. Methods In two sessions, 34 pain-free participants received a painful (hypertonic saline, 5.8%) injection and a control (isotonic saline, 0.9%) injection in the right thigh muscle before performing a 3 min isometric wall squat exercise. Pressure pain thresholds (PPTs) were assessed at both thighs and the left neck/shoulder at baseline, after injections and after exercise. Pain intensities in the thighs were rated on numerical rating scales (NRS: 0–10). Results Hypertonic saline induced moderate thigh pain at rest (NRS: 4.6 ± 2.1) compared to the control injection (NRS: 0.3 ± 0.4; p<0.001). EIH at the thighs and neck/shoulder were not different between sessions (Injected thigh: 0 kPa; 95% CI: −51 to 52; Contralateral thigh: −6 kPa; 95% CI: −42 to 30; neck/shoulder: 19 kPa; 95% CI: −6 to 44). No significant associations between pain intensity ratings immediately after the Painful injection and EIH responses at any assessment sites were found (right thigh: β=0.08, 95% CI: −12.95 to 20.64, p=0.64, left thigh: β=−0.33, 95% CI: −27.86 to 0.44, p=0.06; neck/shoulder: β=−0.18, 95% CI: −15.11 to 4.96, p=0.31). Conclusions Pain in the area of an exercising muscle did not reduce local or systemic EIH responses. Trial registration number NCT04354948.

scholarly journals Muscle pain from an intramuscular injection of hypertonic saline increases variability in knee extensor torque reproduction

2020 ◽  
Author(s):  
Samuel Andrew Smith ◽  
Dominic Micklewright ◽  
Samantha Lee Winter ◽  
Alexis R. Mauger
Keyword(s):  
Hypertonic Saline ◽  
Muscle Pain ◽  
Intramuscular Injection ◽  
Vastus Lateralis ◽  
Isotonic Saline ◽  
Knee Extensor ◽  
Knee Extensors ◽  
Saline Control ◽  
Reproduction Task ◽  
Extensor Torque

Purpose: The intensity of exercise-induced pain (EIP) reflects the metabolic environment in the exercising muscle, so during endurance exercise this may inform the intelligent regulation of work rate. Conversely, the acute debilitating effects of EIP on motor unit recruitment could impair the estimation of force produced by the muscle and impair judgement of current exercise intensity. This study investigated whether muscle pain that feels like EIP, administered via intramuscular injection of hypertonic saline, interferes with the ability to accurately reproduce torque in a muscle group relevant to locomotive exercise. Methods: On separate days, fourteen participants completed an isometric torque reproduction task of the knee extensors. Participants were required to produce torque at 15 and 20% maximal voluntary torque (MVIT), without visual feedback before (Baseline), during (Pain/No Pain), and after (Recovery) an injection of 0.9% isotonic saline (Control) or 5.8% hypertonic saline (Experimental) into the vastus lateralis of the right leg. Results: An elevated reported intensity of pain, and a significantly increased variance in mean contraction torque at both 15% (P=0.049) and 20% (P=0.002) MVIT was observed in the Experimental compared to the Control condition. Both 15 and 20% target torques were performed at a similar pain intensity in the Experimental condition (15% MVIT, 4.2 ± 1.9; 20% MVIT, 4.5 ± 2.2; P>0.05). Conclusion: These findings demonstrate that the increased muscle pain from the injection of hypertonic saline impeded accurate reproduction of knee extensor torque. These findings have implications for the detrimental impact of EIP on exercise regulation and endurance performance.

Experimental Pain in Human Temporal Muscle Induced by Hypertonic Saline, Potassium and Acidity

Cephalalgia ◽  
1992 ◽  
Vol 12 (2) ◽  
pp. 101-106 ◽  
Author(s):  
Kai Jensen ◽  
Michael Norup
Keyword(s):  
Pain Intensity ◽  
Potassium Chloride ◽  
Hypertonic Saline ◽  
Pain Threshold ◽  
Isotonic Saline ◽  
Pressure Pain Threshold ◽  
Experimental Pain ◽  
Ordinal Scale ◽  
Temporal Muscle ◽  
Pressure Pain

The study was aimed at developing a reference model for experimental pain and tenderness in the human temporal muscle by the local injection of hypertonic saline, potassium chloride and acidic phosphate buffer, using isotonic saline as control. The design was randomized and double-blind. Twenty healthy subjects had 0.2 ml test solution injected into one temporal muscle and saline into the other. Following each injection, pain was rated on a 10-point ordinal scale and pressure-pain thresholds were measured every minute for 10 min by a pressure algometer. Hypertonic saline ( n = 11) and potassium chloride ( n = 12) induced significantly more pain than isotonic saline ( ANOVA, p < 0.0001). Compared to control injections, hypertonic saline and potassium chloride induced a significant reduction in pressure-pain threshold (ANOVA, p < 0.0001 and p < 0.05). Forty-eight percent of the injections led to the referral of pain most often to the jaws. A positive correlation between the relative occurrence of referred pain and pain intensity was observed ( p < 0.001) as was a negative correlation between the decrease in pressure-pain threshold and pain intensity ( p < 0.05).

scholarly journals Sterile water; a novel and promising human experimental craniofacial muscle pain model

2021 ◽  
Author(s):  
Sofia Louca Jounger ◽  
Johanna Svedenlöf ◽  
Reija Elenius ◽  
Christoffer Källkrans ◽  
Emil Scheid ◽  
...  
Keyword(s):  
Muscle Pain ◽  
Sterile Water ◽  
Pain Model

scholarly journals Purinergic ATP triggers moxibustion-induced local anti-nociceptive effect on inflammatory pain model

2021 ◽  
Author(s):  
Hai-Yan Yin ◽  
Ya-Peng Fan ◽  
Juan Liu ◽  
Dao-Tong Li ◽  
Jing Guo ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Inflammatory Pain ◽  
Analgesic Effect ◽  
Intramuscular Injection ◽  
High Performance ◽  
Atp Hydrolysis ◽  
Purinergic Signalling ◽  
Pain Model ◽  
Speed Up

AbstractPurinergic signalling adenosine and its A1 receptors have been demonstrated to get involved in the mechanism of acupuncture (needling therapy) analgesia. However, whether purinergic signalling would be responsible for the local analgesic effect of moxibustion therapy, the predominant member in acupuncture family procedures also could trigger analgesic effect on pain diseases, it still remains unclear. In this study, we applied moxibustion to generate analgesic effect on complete Freund’s adjuvant (CFA)-induced inflammatory pain rats and detected the purine released from moxibustioned-acupoint by high-performance liquid chromatography (HPLC) approach. Intramuscular injection of ARL67156 into the acupoint Zusanli (ST36) to inhibit the breakdown of ATP showed the analgesic effect of moxibustion was increased while intramuscular injection of ATPase to speed up ATP hydrolysis caused a reduced moxibustion-induced analgesia. These data implied that purinergic ATP at the location of ST36 acupoint is a potentially beneficial factor for moxibustion-induced analgesia.

Effect of adjunctive sodium hyaluronate versus surfactant nasal irrigation on mucociliary clearance in allergic rhinitis: a single-blind, randomised, controlled study

2021 ◽  
pp. 1-4
Author(s):  
E Ocak ◽  
S Mulazimoglu ◽  
D Kocaoz ◽  
E Mirici ◽  
E Dagli ◽  
...  
Keyword(s):  
Allergic Rhinitis ◽  
Mucociliary Clearance ◽  
Isotonic Saline ◽  
Sodium Hyaluronate ◽  
Controlled Study ◽  
Control Group ◽  
Clearance Time ◽  
Nasal Irrigation ◽  
Persistent Allergic Rhinitis ◽  
Randomised Controlled

Abstract Objective To investigate the effects of nasal irrigation with sodium hyaluronate and surfactant solutions on mucociliary clearance time in patients with mild persistent allergic rhinitis. Methods A total of 120 patients diagnosed with mild persistent allergic rhinitis were enrolled in this prospective study. The patients were allocated randomly to the surfactant, sodium hyaluronate or isotonic saline (as a control) nasal irrigation group. The mucociliary clearance times and improvements in mucociliary clearance times were compared. Results Improvements in mean mucociliary clearance time were significantly greater in the surfactant and sodium hyaluronate groups than in the control group (p < 0.01). The mean post-treatment mucociliary clearance time of the surfactant group was significantly lower than that of the control (p < 0.001) and sodium hyaluronate groups (p = 0.03). Conclusion Surfactant and sodium hyaluronate nasal irrigation solutions may both be used as adjunctive treatments for allergic rhinitis. Surfactant nasal irrigation resulted in better mucociliary clearance times.

Baseline pain characteristics predict pain reduction after physical therapy in women with chronic pelvic pain. Secondary analysis of data from a randomized controlled trial

2020 ◽  
Vol 20 (4) ◽  
pp. 793-800
Author(s):  
Ane S. Nygaard ◽  
Gro K. Haugstad ◽  
Tom Wilsgaard ◽  
Pål Øian ◽  
Mona Stedenfeldt
Keyword(s):  
Randomized Controlled Trial ◽  
Physical Therapy ◽  
Regression Model ◽  
Pain Intensity ◽  
Pelvic Pain ◽  
Chronic Pelvic Pain ◽  
Controlled Trial ◽  
Pain Reduction ◽  
Randomized Controlled ◽  
Pain Duration

AbstractBackground and aimsWomen with chronic pelvic pain represent a heterogeneous group, and it is suggested that the existence of sub-groups can explain varying results and inconclusiveness in clinical trials. Some predictors of treatment outcome are suggested, but the evidence is limited. The primary aim of this study was to explore if selected pre-treatment characteristics of the participants in a recently conducted randomized controlled trial were associated with treatment outcome.MethodsIn this study secondary analysis of data collected in a randomized trial were conducted. The participants were women with chronic pelvic pain randomized to two different physical therapy treatments. Analyses in this study were performed for the whole group as a cohort. The primary outcome measure was change in pain intensity from baseline to 12 months, measured with the numeric rating scale (0–10). The women were asked to rate their mean pelvic pain intensity during the last 7 days. Based on previous research and on available variables from the randomized controlled trial four potential predictive factors were derived from the baseline data and assessed one by one in a linear regression model, adjusted for age and treatment group. The variables with strongest association (p < 0.10) with the primary outcome were further included in a multivariable linear regression model with backward selection, adjusted for age and treatment group.ResultsFifty women (mean age 38.1, SD = 12.2) were included in the analysis. For these women the mean change in pain intensity was −1.2 points (95% CI −1.8 to −0.7) from baseline to 12 months. The multivariable regression model showed that pelvic pain duration of 6 years or more was associated with less decrease in pain intensity with a regression coefficient of 1.3 (95% CI 0.3–2.4). Baseline pain intensity was associated with higher pain reduction after PT treatment with a regression coefficient per SD increase in baseline pain of −0.6 (95% CI −1.1 to −0.1). None of the women with main pain site other places than in the pelvis reported any pain reduction after physical therapy treatment, but due to the small numbers the predictor was not included in the regression analysis.ConclusionsWe identified that pelvic pain duration of 6 years or more was associated with less pain reduction, and that higher baseline pain intensity was associated with higher pain reduction after physical therapy treatment in this sample of women with chronic pelvic pain. For the variable main pain site other places than the pelvis the results are unsure due to small numbers.ImplicationsBased on our finding of long pain duration as a negative predictor for pain reduction, we emphasize that early intervention is important. Many of the participants in our RCT reported pelvic surgeries or other treatments prior to referral for PT, and we suggest that referral to a non-invasive intervention such as PT should be considered at an earlier stage. In order to tailor interventions to the individual women’s needs, thorough baseline assessments, preferably in a multidisciplinary setting, should be performed.

Sign in / Sign up

Export Citation Format

Share Document