Electronic Pressure Algometer Research Articles

Transdermal iontophoresis versus high power pain threshold ultrasound in Mechanical Neck Pain: a randomized controlled trial

BackgroundThe investigation aimed to assess the impacts of magnesium sulphate (MgSO4) iontophoresis and high-power pain-threshold ultrasound (HPPT-US) on pain, range of motion (ROM), and functional activity in physical therapy students suffering from mechanical cervical pain.MethodsTypically, 75 males aged 19 to 30 years suffering from mechanical neck pain were enrolled in this investigation. Participants were divided at random into three groups. Group A received iontophoresis plus conventional physical therapy program, Group B received HPPTUS along with conventional therapy, and Group C received conventional therapy only. The outcomes were pain evaluated by visual analog scale (VAS) and Digital Electronic Pressure Algometer, cervical range of motion measured by Myrin gravity reference goniometer, and Arabic Neck disability index (ANDI) evaluate neck function.ResultsThe differences within and between groups were detected utilizing a mixed-design multivariate analysis of variance (MANOVA). The within- and between-group analysis of all outcome measures revealed that there were statistically significant differences at post-intervention between high-power ultrasound and conventional group at all variables and also between iontophoresis and conventional group, but there was no statistically significant variation between high-power ultrasound and iontophoresis.ConclusionMgSO4 iontophoresis and HPPT-US are effective in decreasing pain, improving neck function, and improving neck ROM in subjects with mechanical neck pain who have active myofascial trigger points (MTrPs) on the upper fibers of the trapezius with no superiority of one over the other.Trail registrationThe study was registered in the Clinical Trials Registry (registration no: NCT05474898) 26/7/2022.

Effects of high-power pain threshold ultrasound technique in patients with knee osteoarthritis: A single-blind randomized controlled trial

Osteoarthritis (OA) is a highly prevalent, degenerative disease of the joints manifested by joint pain, tenderness, decreased function, and limited range of motion (ROM). The current study aimed at evaluating the therapeutic effect of the high-power pain-threshold ultrasound technique (HPPTUS) in comparison with conventional ultrasound (US) techniques in patients with knee osteoarthritis (KOA). A single-masked, pre–post randomized controlled trial was conducted. Fifty participants of both sexes (between 40 and 50 years of age), diagnosed with stage II knee osteoarthritis, participated in this study. They were randomized into two groups: Group A (experimental group, n=25), which received HPPTUS on the knee joint in addition to the traditional treatment (hot packs and isometric exercise for quadriceps), and Group B (control group, n=25), which received conventional ultrasound on knee joint in addition to the traditional treatment (hot packs and isometric exercise for quadriceps). Both groups underwent a four-week treatment plan in which sessions were conducted twice per week. The visual analogue scale (VAS) was used to estimate the intensity of pain, Digital Electronic Pressure Algometer was used to measure pressure pain threshold (PPT) on trigger point around knee, and Digital goniometer was utilized to assess ROM of the knee joint before and after treatment. The MANOVA test revealed statistically significant improvements in all variables (VAS, PPT, knee ROM) post-treatment compared to pre-treatment values in the HPPTUS group (experimental group) (p < 0.05), while the control group revealed statistically significant improvement only in VAS post-treatment compared with pre-treatment (p < 0.05). Comparison between groups revealed statistically significant improvements in VAS, PPT, knee ROM in participants receiving HPPTUS compared with the control group (p < 0.05). High-power ultrasound can be effectively implemented in the treatment of knee OA as it produces significant improvements in the intensity of pain, pressure-pain threshold, and knee joint ROM.

Total tenderness score and pressure pain thresholds in persistent post-traumatic headache attributed to mild traumatic brain injury

ObjectiveTo investigate whether persistent post-traumatic headache attributed to mild traumatic brain injury (TBI) is associated with more pronounced pericranial tenderness and lower pressure pain thresholds (PPTs) in the head and neck region, compared with healthy controls.MethodsPatients with persistent post-traumatic headache (n = 100) and age- and gender-matched healthy controls (n = 100) were included between July 2018 and June 2019. Total tenderness score (TTS) was used to assess pericranial tenderness by bilateral manual palpation in eight muscles or tendon insertions. Summation was then used to calculate a TTS from 0 to 48 based on individual right- and left-sided scores; higher TTS score indicated more pronounced pericranial tenderness. PPTs were examined in m. temporalis and m. trapezius (upper and middle part) using an electronic pressure algometer that applies increasing blunt pressure at a constant rate.ResultsThe TTS score was higher in patients with persistent post-traumatic headache (median, 21; IQR, 12–31), compared with healthy controls (median, 10; IQR, 6–17; P < .001). PPTs were lower in patients with persistent post-traumatic headache than in controls in both the left-sided m. temporalis (mean ± SD, 157.5 ± 59.9 vs. 201.1 ± 65.2; P < .001) and right-sided m. temporalis (mean ± SD, 159.5 ± 63.8 vs. 212.3 ± 61.9; P < .001). Furthermore, patients with persistent post-traumatic headache also had lower left- and right-sided PPTs in the upper as well as middle part of m. trapezius, compared with healthy controls; all P values were .05 or less.ConclusionsAmong patients with persistent post-traumatic headache, pericranial tenderness was more pronounced and PPTs in the head and neck region were lower than in healthy controls free of headache and mild TBI. Further research is needed to better understand the involvement of pericranial myofascial nociceptors in the disease mechanisms underlying post-traumatic headache.

An Experimental Investigation of the Effect of Age and Sex/Gender on Pain Sensitivity in Healthy Human Participants

Background: Ageing is associated with alterations of the structure and function of somatosensory tissue that can impact on pain perception. The aim of this study was to investigate the relationship between age and pain sensitivity responses to noxious thermal and mechanical stimuli in healthy adults. Methods: 56 unpaid volunteers (28 women) aged between 20 and 55 years were categorised according to age into one of seven possible groups. The following measurements were taken: thermal detection thresholds, heat pain threshold and tolerance using a TSA-II NeuroSensory Analyzer; pressure pain threshold using a handheld electronic pressure algometer; and cold pressor pain threshold, tolerance, intensity and unpleasantness. Results: There was a positive correlation between heat pain tolerance and age (r = 0.228, P = 0.046), but no statistically significant differences between age groups for cold or warm detection thresholds, or heat pain threshold or tolerance. Forward regression found increasing age to be a predictor of increased pressure pain threshold (B = 0.378, P = 0.002), and sex/gender to be a predictor of cold pressor pain tolerance, with women having lower tolerance than men (B = -0.332, P = 0.006). Conclusion: The findings of this experimental study provide further evidence that pressure pain threshold increases with age and that women have lower thresholds and tolerances to innocuous and noxious thermal stimuli. Significance: The findings demonstrate that variations in pain sensitivity response to experimental stimuli in adults vary according to stimulus modality, age and sex and gender.

Test procedures to assess somatosensory abnormalities in individuals with back pain: a systematic review of psychometric properties

Background: Identification of somatosensory abnormalities in patients with low back pain (LBP) is essential for targeted treatment strategies in an attempt to reduce or normalize altered sensory processing within the central nervous system. Several test procedures have been used to assess somatosensory abnormalities in patients with LBP, however, these test procedure should possess optimal psychometric properties (PMPs) to be used in clinical practice.Objectives: To systematically review the literature to evaluate the level of evidence for PMPs of test procedures administered to identify somatosensory abnormalities in individuals with LBP.Methods: A comprehensive electronic literature search was conducted in seven databases from inception to March 2016. The QAREL checklist and the COSMIN tool were used to assess methodological quality of the included studies. The level of evidence was determined based on the methodological quality of included studies and the quality of statistical measures of measurement properties.Results: Nineteen studies related to LBP were included. Studies demonstrated limited evidence for reliability and discriminative validity for cross-friction algometry in sub-acute LBP. Additionally, moderate evidence of reliability and strong evidence of discriminative validity exists for: electronic pressure algometer in chronic LBP, and a decline of conditioned pain modulation using the electronic pressure algometer (test stimulus) and a cold presser (conditioning stimulus) in acute and chronic LBP.Conclusions: This systematic review identified test procedures which demonstrated acceptable PMPs. Further research with adequate methodological quality and standardized protocols is recommended to investigate the predictive ability and responsiveness of test procedures to ensure their extended clinical utility.

Effect of Perioperative Electroacupuncture as An Adjunctive Therapy on Postoperative Analgesia with Tramadol and Ketamine in Prostatectomy: A Randomised Sham-Controlled Single-Blind Trial

To study the analgesic effect of electroacupuncture (EA) as perioperative adjunctive therapy added to a systemic analgesic strategy (including tramadol and ketamine) for postoperative pain, opioid-related side effects and patient satisfaction. In a sham-controlled participant- and observer-blinded trial, 75 patients undergoing radical prostatectomy were randomly assigned to two groups: (1) EA (n=37; tramadol+ketamine+EA) and (2) control (n=38; tramadol+ketamine). EA (100 Hz frequency) was applied at LI4 bilaterally during the closure of the abdominal walls and EA (4 Hz) was applied at ST36 and LI4 bilaterally immediately after extubation. The control group had sham acupuncture without penetration or stimulation. The following outcomes were evaluated: postoperative pain using the Numerical Rating Scale (NRS) and McGill Scale (SF_MPQ), mechanical pain thresholds using algometer application close to the wound, cortisol measurements, rescue analgesia, Spielberger State Trait Anxiety Inventory (STAI Y-6 item), patient satisfaction and opioid side effects. Pain scores on the NRS and SF_MPQ were significantly lower and electronic pressure algometer measurements were significantly higher in the EA group than in the control group (p<0.001) at all assessments. In the EA group a significant decrease in rescue analgesia was observed at 45 min (p<0.001) and a significant decrease in cortisol levels was also observed (p<0.05). Patients expressed satisfaction with the analgesia, especially in the EA group (p<0.01). Significant delays in the start of bowel movements were observed in the control group at 45 min (p<0.001) and 2 h (p<0.05). Adding EA perioperatively should be considered an option as part of a multimodal analgesic strategy.

The repeatability of pressure algometry in asymptomatic individuals over consecutive days

BackgroundTo determine if electronic pressure algometry is a statistically stable measure of spinal pressure pain threshold (PPT) in asymptomatic individuals, in particular, to determine if repeated measurements at the same site changes the PPT, and to determine if repeatability differs in each of the spinal regions tested. DesignRepeated measures design. SettingUniversity teaching clinic. ParticipantsThirty-three asymptomatic participants. InterventionsThe PPT of three spinal segments (C6, T6 and L4) was measured three times in consecutive measures (10 s apart), then repeated one day and two days post-initial measurement. Measurements were taken using an electronic pressure algometer. Main outcome measuresPPT, intra-class correlation coefficient and test of significant equality. ResultsResults demonstrated that the PPT measurement is statistically stable both between days (p < 0.001) and within day (p < 0.001). The intra-class correlation coefficient (ICC) values between the mean scores of daily trials demonstrated excellent concordance for each spinal segment (ICC = 0.860–0.953), with the exception of the correlation between day 1 and day 3 at T6, demonstrating good concordance (ICC = 0.676). All trial-to-trial correlations demonstrated excellent concordance both within trials of the same day (ICC = 0.833–0.988) and subsequent days (ICC = 0.823–0.940). ConclusionElectronic pressure algometry is a repeatable and statistically stable measure of the spinal PPT, both between days and within-day. The results provide evidence that the use of this device may be of value as an outcome measure for primary spinal complaints such as low back or thoracic spine pain.

Algometry with a clothes peg compared to an electronic pressure algometer: a randomized cross-sectional study in pain patients

BackgroundHypersensitivity of the central nervous system is widely present in pain patients and recognized as one of the determinants of chronic pain and disability. Electronic pressure algometry is often used to explore aspects of central hypersensitivity. We hypothesized that a simple pain provocation test with a clothes peg provides information on pain sensitivity that compares meaningfully to that obtained by a well-established electronic pressure algometer. "Clinically meaningful" was defined as a medium (r = 0.3-0.5) or high (r > 0.5) correlation coefficient according to Cohen's conventions.MethodsWe tested 157 in-patients with different pain types. A calibrated clothes peg was applied for 10 seconds and patients rated the pain intensity on a 0 to 10 numerical rating scale. Pressure pain detection threshold (PPdt) and pressure pain tolerance threshold (PPtt) were measured with a standard electronic algometer. Both methods were performed on both middle fingers and ear lobes. In a subgroup of 47 patients repeatability (test-retest reliability) was calculated.ResultsClothes peg values correlated with PPdt values for finger testing with r = -0.54 and for earlobe testing with r = -0.55 (all p-values < 0.001). Clothes peg values also correlated with PPtt values for finger testing with r = -0.55 (p < 0.001). Test-retest reliability (repeatability) showed equally stable results for clothes peg algometry and the electronic algometer (all r-values > 0.89, all p-values < 0.001).ConclusionsInformation on pain sensitivity provided by a calibrated clothes peg and an established algometer correlate at a clinically meaningful level.

Multiple Active Myofascial Trigger Points and Pressure Pain Sensitivity Maps in the Temporalis Muscle Are Related in Women With Chronic Tension Type Headache

To describe the common locations of active trigger points (TrPs) in the temporalis muscle and their referred pain patterns in chronic tension type headache (CTTH), and to determine if pressure sensitivity maps of this muscle can be used to describe the spatial distribution of active TrPs. Forty women with CTTH were included. An electronic pressure algometer was used to assess pressure pain thresholds (PPT) from 9 points over each temporalis muscle: 3 points in the anterior, medial and posterior part, respectively. Both muscles were examined for the presence of active TrPs over each of the 9 points. The referred pain pattern of each active TrP was assessed. Two-way analysis of variance detected significant differences in mean PPT levels between the measurement points (F=30.3; P<0.001), but not between sides (F=2.1; P=0.2). PPT scores decreased from the posterior to the anterior column (P<0.001). No differences were found in the number of active TrPs (F=0.3; P=0.9) between the dominant side the nondominant side. Significant differences were found in the distribution of the active TrPs (chi2=12.2; P<0.001): active TrPs were mostly found in the anterior column and in the middle of the muscle belly. The analysis of variance did not detect significant differences in the referred pain pattern between active TrPs (F=1.1, P=0.4). The topographical pressure pain sensitivity maps showed the distinct distribution of the TrPs indicated by locations with low PPTs. Multiple active TrPs in the temporalis muscle were found, particularly in the anterior column and in the middle of the muscle belly. Bilateral posterior to anterior decreased distribution of PPTs in the temporalis muscle in women with CTTH was found. The locations of active TrPs in the temporalis muscle corresponded well to the muscle areas with lower PPT, supporting the relationship between multiple active muscle TrPs and topographical pressure sensitivity maps in the temporalis muscle in women with CTTH.

Pressure Pain Sensitivity Mapping of the Temporalis Muscle Revealed Bilateral Pressure Hyperalgesia in Patients with Strictly Unilateral Migraine

Previous studies on pressure pain sensitivity in patients with migraine have shown conflicting results. There is emerging evidence suggesting that pain sensitivity is not uniformly distributed over the muscles, indicating the existence of topographical changes in pressure pain sensitivity. The aim of this study was to calculate topographical pressure pain sensitivity maps of the temporalis muscle in a blind design in patients with strictly unilateral migraine compared with controls. For this purpose, an electronic pressure algometer was used to measure pressure pain thresholds (PPT) over nine points of the temporalis muscle: three points in the anterior, medial and posterior parts, respectively. Pressure pain sensitivity maps of both sides (dominant or non-dominant; symptomatic or non-symptomatic) were calculated. The analysis of variance showed significant differences in PPT values between both groups (F = 279.2; P < 0.001) and points (F = 4.033; P < 0.001). Patients showed lower PPT at all nine points than healthy controls (P < 0.001). We also found lower PPT in the centre of the muscle compared with the posterior part of the muscle within both groups (P < 0.01). Interaction between group and points (F = 1.9; P < 0.05) was also found. Within the migraine group, PPT levels were decreased bilaterally from the posterior to the anterior column of the temporalis muscle (Student-Newman- Keuls analysis; P < 0.05), with the most sensitive in the anterior part of the muscle. For controls, PPT did not follow such anatomical distribution, the most sensitive point being the centre of the mid-muscle belly. This study showed bilateral sensitization to pressure in unilateral migraine, suggesting the involvement of central components.

Pressure-Pain Threshold Algometric Measurement in Patients With Greater Trochanteric Pain After Total Hip Arthroplasty

The evaluation of tenderness associated with greater trochanteric pain (GTP) syndrome is amenable to bias and depends on the examiner's experience. In this study, we tested whether the use of an electronic pressure algometer enhanced the reliability of this evaluation. Pressure-pain threshold (PPT) was measured with an electronic algometer in 18 patients who developed GTP after total hip arthroplasty and in matched controls. Both groups were evaluated with visual analog scale. The PPT measurements showed large interindividual variability across patients. The correspondence of the PPT measurements in asymptomatic patients was good. We found good validity for the algometer used. The PPT ratio of 0.8 (affected vs. unaffected side) can be used as a cut-off ratio. The PPT measurements at the greater trochanter (local pain) were significantly lower than at the ilio-tibial band (radiated pain). There was no correlation between PPT measurements and visual analog scales. Despite the acceptable sensitivity and specificity of pressure algometer, because of low positive predictive value and large interindividual variability, pressure algometer has a limited value as a screening test. The examination of tenderness associated with GTP is facilitated by the used algometer. It is the intraindividual body-side PPT differences that yield the most sensitive measurement for the assessment of deep pain. A cut-off value of 0.8 can be used for diagnostic purposes. Interindividual differences might be considerable and could mask pathologic diagnostic findings.

Influence of scapular position on the pressure pain threshold of the upper trapezius muscle region

A position of scapula depression will maintain the upper trapezius muscle region in a lengthened position, causing excessive strain. This strain could lead to peripheral nociceptive nerves sensitization in the affected area, changing the pressure pain threshold (PPT). Thus, people with a faulty alignment of scapular depression may have lower PPT levels in the upper trapezius region when compared to subjects with normal vertical scapular position. The purpose of this double-blind study was to assess the influence of scapular position on the PPT of the upper trapezius region in a young healthy population. Fifty two physical therapy students of the Catholic University of Minas Gerais – PUC-Minas, Brazil, with normal shoulder (NS group, n = 26, 6 men and 20 women) or depressed shoulder (DS group, n = 26, 6 men and 20 women) volunteered to participate in this study. An electronic pressure algometer was used to measure the PPT on the upper trapezius muscle region. The results showed a significant difference between groups, with the DS group (19.0 ± 9.0 N/cm 2) demonstrated lower mean PPT values when compared to NS group (26.1 ± 9.6 N/cm 2) ( p < 0.01). Our results showed that healthy young subjects with depressed scapula position had significant lower upper trapezius PPT values when compared to subjects with normal scapula position.

Validity of an electronic pressure algometer

Background Pressure algometry is one of a number of outcome measures that manual therapy practitioners are able to use in both clinical and research settings. The pressure algometer is used to determine the pressure pain threshold of specific muscle and bone locations. Objective To determine the validity of a commonly utilised electronic pressure algometer. Design A repeated measures design was used. Setting Biomechanics Laboratory, Victoria University, Melbourne. Methods A total of 300 measurements were collected from the electronic pressure algometer as it was applied perpendicularly to an AMTI force plate. Thirty (30) measurements were taken at five discrete rates of application; 10 kPa/s, 20 kPa/s, 30 kPa/s, 40 kPa/s and 50 kPa/s on two separate occasions. Maximum data were recorded from both the pressure algometer and force plate and analysed using the Intraclass Correlation Coefficient (ICC) statistic and the test for significant equality. Results ICC values between the raw pressure algometer maximum values and the converted force plate data were high (ICC 0.905–0.998) for the two separate testing sessions and for both sessions combined (ICC 0.968–0.994). The test of significant equality revealed however that the data could not be considered as significantly the same even when allowing for a 5% or 10% tolerance. Conclusion The results indicate that the electronic pressure algometer utilised in this study demonstrates limited validity in the laboratory setting.

This Month in Anesthesiology

This Month in Anesthesiology

Relationship between low-back pain, muscle spasm and pressure pain thresholds in patients with lumbar disc herniation

It is not known whether or not muscle spasm of the back muscles presented in patients with sciatic scoliosis caused by lumbar disc herniation produces muscle pain and/or tenderness. Pressure pain thresholds (PPTs) of the lower back and low-back pain were examined in 52 patients (13 of 52 presenting sciatic scoliosis) with lumbar disc herniation who complained of radicular pain and in 15 normal subjects. PPTs were measured at five points bilaterally using an electronic pressure algometer. Low-back pain was evaluated using visual analogue scale (VAS) ratings. All patients complained of radicular leg pain and were divided into the following three groups according to the presence of and the region of low-back pain: no low-back pain group, low-back pain with no laterality group, and low-back pain dominantly on the herniation side group; the VAS rating on the side ipsilateral to the herniation side was higher than that on the contralateral side. In the normal subjects, there were no statistically significant differences between sides in mean PPTs at all sites examined. PPTs were not lower in the spasmodic side (concave side) than the convex side in patients with sciatic scoliosis. PPTs on the herniation side were significantly lower than those on the contralateral side in patients with low-back pain dominantly on the herniation side. Furthermore, the areas of low PPTs were beyond the innervation area of dorsal ramus of L5 and S1 nerve root. It was considered that not only the peripheral mechanisms but also the hyper excitability of the central nervous system might contribute in lowering PPTs of the lower back on the herniation side.

The effect of manipulation and mobilisation on pressure pain thresholds in the thoracic spine

High velocity low amplitude (HVLA) thrust manipulation and mobilisation are commonly used by manual therapists to relieve spinal pain and improve mobility. The aim of this controlled, single blinded study was to investigate the effect of manipulation and mobilisation on pressure-pain thresholds (PPT) in the thoracic spine in an asymptomatic population. Subjects (N=96) were screened for tender thoracic segments, and PPT measurements were made using an electronic pressure algometer immediately before and after treatment intervention. Subjects were randomly allocated into three intervention groups, and received either a single high velocity extension thrust, thirty seconds of extension mobilisation, or thirty seconds of sham treatment (control) consisting of ‘laser acupuncture’. Within-group pre and post-intervention PPT values were analysed using dependent t-tests, revealing significant changes in the mobilisation (p<0.01) and manipulation (p=0.04) groups, but not the sham treatment group (p=0.88). Analysis of mean group changes with a one-way ANOVA and post-hoc analysis revealed a significant difference between the mobilisation and control group (p=0.01), but no significant difference between the manipulation and control group (p=0.67). Pre-post effect sizes in the mobilisation group were medium to large (d=0.72), small to medium for manipulation (d=0.32), and small in the control group (d=0.02). Both manipulation and mobilisation produced significantly increased PPTs (decreased sensitivity to pressure) in the thoracic spine, whereas the sham treatment did not. Mobilisation appeared to be more effective than manipulation for increasing PPTs when applied to the thoracic spine in asymptomatic subjects.

The influence of electroconvulsive therapy on pain threshold and pain tolerance in major depression patients before, during and after treatment

Despite the findings that pain and depression are not always directly linked, enough evidence suggest that a complex relationship between pain and depression exists. Using an electronic pressure algometer placed on the sternum, the changes in pressure pain threshold (PPThr) and pressure pain tolerance (PPTol) were evaluated in 19 patients affected by refractory major depression without psychotic features, throughout a full course of electroconvulsive therapy (ECT) treatment. Measurements were done before the first treatment, after the 6th treatment and after the last treatment. After the 6th treatment, mean (±SD) PPThr increased significantly from 11.48 (±4.81) kg/cm 2 at baseline, to 13.7 (±5.59) kg/cm 2 ( p=0.0076) while PPTol did not change significantly (from 18.46 (±6.75)kg/cm 2 to 17.4 (±8.1) kg/ cm 2 ). At the end of the treatment course, mean (±SD) PPThr did not increase further significantly (15.06 (±5.21) kg/ cm 2 ( p=0.0234)) while PPTol increased significantly to 21.34 (±7.8)kg/cm 2 ( p=0.0047). ECT’s efficacy was measured with the 21-item Hamilton Rating Scale for Depression (21-HAM-D). Mean (±SD) 21-HAM-D scores decreased significantly from 30.9 (±4.15) at baseline, to 10.47 (±5.78) ( p=0.0001) after the 6th treatment, with no further significant change at the end of the treatment course (9.94±3.07; p=0.0254). Both pain threshold and pain tolerance increased following the alleviation of the depressive disorder and a possible usefulness of ECT may be postulated for treating severe, chronic pain syndromes. However, a more significant conclusion is that the increase of the PPThr noted early during ECT treatment may serve as an early outcome possible detector of ECT efficacy in depressed patients.

Sensory changes during the ovulatory phase of the menstrual cycle in healthy women

This study compared the pain sensitivity in healthy women at the abdomen and lower back (presumed referral areas of menstrual pain), thigh and arm (control areas), in the menstrual, ovulatory, luteal and premenstrual phases of confirmed ovulatory cycles, with that of males. The pressure pain threshold (PPT) and pinch pain threshold (PiPT) was determined by an electronic pressure algometer, heat pain threshold (HPT) by a contact thermode and tactile threshold (TT) with von Frey hairs. The abdominal PPT was significantly lower in females in all menstrual phases as compared to the control sites ( p<0.0007). The abdominal and lower back HPT was significantly lower in females in all menstrual phases compared with control areas, and to the sites in males ( p<0.002). The TT was significantly reduced in females compared with males ( p< 0.013). There was no difference in the PiPT between females and males. In males, the HPT, PPT and TT were not different within any site. During the ovulatory phase, the HPT was significantly reduced at the abdomen and the PPT at the back compared with the menstrual, luteal and premenstrual phases (p<0.0002). There were no within-menstrual phase variations in the PiPT and TT at any site, or for the HPT and PPT at the control areas. The reduced thresholds in menstruating women may be due to the presence of latent uterine algogenic stimuli, and the increased levels of oestrogen and leuteinizing hormone at ovulation may enhance nociception by acting both at the peripheral and central level, resulting in the hypersensitivity changes at the abdomen and lower back areas. Copyright 2001 European Federation of Chapters of the International Association for the Study of Pain Copyright 2001 European Federation of Chapters of the International As̋Ér the Study of Pain

Immediate effects of the serotonin antagonist granisetron on temporomandibular joint pain in patients with systemic inflammatory disorders

The aim of this study was to investigate if the 5-HT 3 antagonist granisetron reduces temporomandibular joint (TMJ) pain in patients with systemic inflammatory joint disorders. Sixteen patients with systemic inflammatory joint disease with pain localized over the TMJ region and tenderness to digital palpation of the TMJ were included. The current resting pain (VAS Rest) and the pain during maximum mouth opening (VAS MVM) of the TMJs were assessed with a 100 mm visual analogue scale. An electronic pressure algometer was used to estimate the pressure pain threshold (PPT) over the lateral aspect of the TMJ. Venous blood was collected for measurement of the plasma and serum levels of 5-HT, erythrocyte sedimentation rate, rheumatoid factor and C-reactive protein. The selective 5-HT 3 receptor antagonist granisetron or saline were injected into the posterior part of the upper TMJ compartment in a randomized double-blind manner. The patients in the granisetron group had lower VAS Rest than the patients in the saline group after 10 min. In the granisetron group, VAS Rest was decreased after 10 min, while VAS MVM was decreased and PPT increased after 20 min. In the saline group, VAS MVM was decreased after 20 min. In conclusion, granisetron has an immediate, short-lasting and specific pain reducing effect in TMJ inflammatory arthritis. The 5-HT 3 receptor may therefore be involved in the mediation of TMJ pain in systemic inflammatory joint disorders.

Pressure pain thresholds and electromyographically defined muscular fatigue induced by a muscular endurance test in normal women.

This study was undertaken to examine the relation between muscular tenderness measured as pressure pain thresholds (PPTs) and electromyographic (EMG) signs of fatigue before and after a local standardized static muscle contraction. Pressure pain thresholds were measured in the shoulder region before, immediately after, and 10 minutes after a standardized static endurance test while monitoring the EMG signs of local muscular fatigue and its recovery. The study did not address local biochemical issues. The study was conducted at the Department of Rehabilitation, Lund University Hospital, Lund, Sweden. Twenty-five healthy female volunteers without musculoskeletal problems participated in this study. A static endurance test was performed, which consisted of a submaximal unilateral activation of the right trapezius and deltoid muscles for as long as possible. Bilateral PPTs over the trapezius and deltoid muscles were measured with an electronic pressure algometer. Established surface EMG parameters of local muscular fatigue were assessed. The Borg Rating of Perceived Exertion scale was used. The average endurance time was 330 seconds. Immediately after the test, significant bilateral increases in the normalized PPTs over both muscles were found, although the increase was more pronounced on the test side: over the right trapezius muscle by 13% (p <0.001), over the right deltoid muscle by 23% (p <0.001), and over the left trapezius and deltoid muscles by 6% (p = 0.04) and (p = 0.009), respectively. These increases persisted 10 minutes after the end of the test. The subjects developed significant signs of fatigue as defined by EMG criteria in both muscles on the right side during the test. The recovery from fatigue was approximately half complete 15 seconds after the end of the test and complete or almost complete 10 minutes thereafter. Pressure pain thresholds over shoulder muscles remained elevated up to 10 minutes after a unilateral static endurance test. This time course was completely different from that of EMG-defined muscle fatigue, which showed a fast recovery. These findings indicate that the mechanisms of recovery from fatigue and nociception are independent of each other. The bilateral PPT increases might be explained by central antinociceptive mechanisms activated by static muscle work.