Quantitative Sensory Testing Measures Research Articles

Altered somatosensory profile according to quantitative sensory testing in patients with degenerative lumbar spine disorders scheduled for surgery

BackgroundSomatosensory profiling in affected and non-affected body regions can strengthen our insight regarding the underlying pain mechanisms, which can be valuable in treatment decision making and to improve outcomes, in patients with degenerative lumbar spine disorders pre-surgery. The aim was to describe somatosensory profiles in patients with degenerative lumbar spine disorders, to identify the proportion with altered somatosensory profile, and to analyze demographic characteristics, self-reported function, pain, and health pre- and 3 months post-surgery.MethodsIn this prospective cohort study in a Spine Clinic, 105 patients scheduled for surgery for spinal stenosis, disc herniation, degenerative disc disease, or spondylolisthesis were consecutively recruited. Exclusion criteria were; indication for acute surgery or previous surgery at the same spinal level or severe grade of pathology. Quantitative sensory testing (QST) and self-reported function, pain, and health was measured pre- and 3 months post-surgery. The somatosensory profile included cold detection threshold, warmth detection threshold, cold pain threshold, heat pain threshold and pressure pain threshold in affected and non-affected body regions.ResultsOn a group level, the patients’ somatosensory profiles were within the 95% confidence interval (CI) from normative reference data means. On an individual level, an altered somatosensory profile was defined as having two or more body regions (including a non-affected region) with QST values outside of normal ranges for reference data. The 23 patients (22%) with altered somatosensory profiles, with mostly loss of function, were older (P = 0.031), more often female (P = 0.005), had higher back and leg pain (P = 0.016, 0.020), lower mental health component summary score (SF-36 MCS) (P = 0.004) and larger pain distribution (P = 0.047), compared to others in the cohort. Post-surgery there was a tendency to worse pain, function and health in the group with altered somatosensory profile pre-surgery.ConclusionsOn a group level, patients with degenerative lumbar spine disorders scheduled for surgery were within normal range for the QST measurements compared to reference values. On an individual level, an altered somatosensory profile outside of normal range in both affected and non-affected body regions occurred in 22% of patients, which may indicate disturbed somatosensory function. Those patients had mostly loss of sensory function and had worse self-reported outcome pre-surgery, compared to the rest of the cohort. Future prospective studies are needed to further examine whether these dimensions can be useful in predicting post-surgery outcome and guide need of additional treatments.

A longitudinal, multimodal approach to characterizing chemotherapy-induced peripheral neuropathy.

e21595 Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a complex, dose-limiting toxicity impacting prognosis and quality of life. The optimal approach to identification and assessment remains unclear. This study aims to prospectively characterize the development and trajectory of CIPN using a combination of patient-reported outcomes (PROs) and objective Quantitative Sensory Testing (QST) measures in gynaecological, colorectal and lung cancer patients receiving neurotoxic platinum and/or taxane-based chemotherapy. Methods: Patients (n = 33, mean age 60.8) were evaluated at baseline prior to chemotherapy, during (every 3 weeks) and post-treatment every 3 months up to 1 year. Assessments at each time point included: PRO (EORTC QLQ-CIPN20 questionnaire) and QST measures (thermal and mechanical detection and grooved pegboard test). Statistical modelling using repeated measures analysis by patient was conducted. Results: Significant and parallel changes were observed in PROs and QST measures over time. Total EORTC score (sensory, motor and autonomic) increased in severity from baseline at all time points, peaking at 3 months post-treatment (34.8% increase; p < 0.0001) and persisting at 1 year (17.9% increase; p = 0.01). Every increase by one point in EORTC sensory score over time corresponded with an elevation in QST parameters: warm detection threshold (upper limb; p = 0.02 and lower limb; p = 0.03) and mechanical detection threshold, MDT (upper limb; p = 0.04 and lower limb; p = 0.02). Equally, rising total EORTC and motor score were related to increasing MDT in the upper limb p = 0.02 and p = 0.003 respectively. A delay of one second taken to complete the grooved pegboard test (dominant hand) was linked to a proportional increase in EORTC motor score (p = 0.01). Conclusions: Associations are shown here amongst PROs and QST parameters providing an opportunity to quantify and synthesize objective with subjective measures of neuropathy in CIPN patients. This may have potentially informative implications to underlying mechanisms of CIPN symptom burden, contributing to a more comprehensive clinical picture and allow stratification of patients by phenotype severity. Additional studies are warranted.

Quantitative sensory testing measures individual pain responses in emergency department patients.

BackgroundRefining and individualizing treatment of acute pain in the emergency department (ED) is a high priority, given that painful complaints are the most common reasons for ED visits. Few tools exist to objectively measure pain perception in the ED setting. We speculated that variation in perception of fixed painful stimuli would explain individual variation in reported pain and response to treatment among ED patients.Materials and methodsIn three studies, we 1) describe performance characteristics of brief quantitative sensory testing (QST) in 50 healthy volunteers, 2) test effects of 10 mg oxycodone versus placebo on QST measures in 18 healthy volunteers, and 3) measure interindividual differences in nociception and treatment responses in 198 ED patients with a painful complaint during ED treatment. QST measures adapted for use in the ED included pressure sensation threshold, pressure pain threshold (PPT), pressure pain response (PPR), and cold pain tolerance (CPT) tests.ResultsFirst, all QST measures had high inter-rater reliability and test–retest reproducibility. Second, 10 mg oxycodone reduced PPR, increased PPT, and prolonged CPT. Third, baseline PPT and PPR revealed hyperalgesia in 31 (16%) ED subjects relative to healthy volunteers. In 173 (88%) ED subjects who completed repeat testing 30 minutes after pain treatment, PPT increased and PPR decreased (Cohen’s dz 0.10–0.19). Verbal pain scores (0–10) for the ED complaint decreased by 2.2 (95% confidence intervals [CI]: 1.9, 2.6) (Cohen’s dz 0.97) but did not covary with the changes in PPT and PPR (r=0.05–0.13). Treatment effects were greatest in ED subjects with a history of treatment for anxiety or depression (Cohen’s dz 0.26–0.43) or with baseline hyperalgesia (Cohen’s dz 0.40–0.88).ConclusionQST reveals individual differences in perception of fixed painful stimuli in ED patients, including hyperalgesia. Subgroups of ED patients with hyperalgesia and psychiatric history report larger treatment effects on ED pain and QST measures.

Multifactorial assessment of measurement errors affecting intraoral quantitative sensory testing reliability

Background and purpose (aims)Measurement error of intraoral quantitative sensory testing (QST) has been assessed using traditional methods for reliability, such as intraclass correlation coefficients (ICCs). Most studies reporting QST reliability focused on assessing one source of measurement error at a time, e.g., inter- or intra-examiner (test–retest) reliabilities and employed two examiners to test inter-examiner reliability. The present study used a complex design with multiple examiners with the aim of assessing the reliability of intraoral QST taking account of multiple sources of error simultaneously. MethodsFour examiners of varied experience assessed 12 healthy participants in two visits separated by 48h. Seven QST procedures to determine sensory thresholds were used: cold detection (CDT), warmth detection (WDT), cold pain (CPT), heat pain (HPT), mechanical detection (MDT), mechanical pain (MPT) and pressure pain (PPT). Mixed linear models were used to estimate variance components for reliability assessment; dependability coefficients were used to simulate alternative test scenarios. ResultsMost intraoral QST variability arose from differences between participants (8.8–30.5%), differences between visits within participant (4.6–52.8%), and error (13.3–28.3%). For QST procedures other than CDT and MDT, increasing the number of visits with a single examiner performing the procedures would lead to improved dependability (dependability coefficient ranges: single visit, four examiners=0.12–0.54; four visits, single examiner=0.27–0.68). A wide range of reliabilities for QST procedures, as measured by ICCs, was noted for inter- (0.39–0.80) and intra-examiner (0.10–0.62) variation. ConclusionReliability of sensory testing can be better assessed by measuring multiple sources of error simultaneously instead of focusing on one source at a time. In experimental settings, large numbers of participants are needed to obtain accurate estimates of treatment effects based on QST measurements. This is different from clinical use, where variation between persons (the person main effect) is not a concern because clinical measurements are done on a single person. ImplicationsFuture studies assessing sensory testing reliability in both clinical and experimental settings would benefit from routinely measuring multiple sources of error. The methods and results of this study can be used by clinical researchers to improve assessment of measurement error related to intraoral sensory testing. This should lead to improved resource allocation when designing studies that use intraoral quantitative sensory testing in clinical and experimental settings.

(442) Racial/ethnic differences in experimental pain sensitivity and associated factors – cardiovascular responsiveness and psychological status

This study aimed to evaluate the contributions of psychological status and cardiovascular responsiveness to racial/ethnic differences in experimental pain sensitivity. Data collected from 3,159 TMD-free individuals - non-Hispanic white (NHW): 1,637, African-American (AA): 1,012, Asian: 299, and Hispanic: 211 - from the OPPERA prospective cohort study were used. Variables analyzed included: quantitative sensory testing measures for pressure, mechanical cutaneous, and heat pain, cardiovascular responsiveness measures (BP, HR, HR/MAP ratio, and heart rate variability), and psychological status (depression, anxiety, stress, coping, and catastrophizing). Structural equation modeling was used for mediation analyses. Putative mediators that showed significant racial/ethnic differences were entered into the final models simultaneously with age, gender, BMI, geographic study site, and education and income level as covariates. Pain catastrophizing was a significant mediator for the associations between race and heat pain tolerance, heat pain ratings (HPR), heat pain aftersensations (HPA), mechanical cutaneous pain ratings and aftersensations (MCPRAS), and mechanical cutaneous pain temporal summation (MCPTS) for both Asians and AAs compared to NHWs. HR/MAP index showed a significant negative mediating effect on the association between race (AAs vs. NHWs) and heat pain tolerance. Coping negatively mediated the association between race and heat pain tolerance, HPR, and MCPTS in both AAs and Asians, compared to NHWs. Negative emotion was a significant mediator for the associations between race (Asians vs. NHWs) and mechanical cutaneous pain thresholds, HPR, HPA, and MCPRAS. Underlying factors responsible for racial differences in pain sensitivity are complex, but both psychological and cardiovascular factors appear to be relevant mediators. Further clinical and experimental research is required to increase our understanding of the suggested mechanisms explaining racial/ethnic differences in pain sensitivity found in the current study and to extend our findings to clinical pain populations.

Thermal QST Phenotypes Associated with Response to Lumbar Epidural Steroid Injections: A Pilot Study.

Response to lumbar epidural steroid injection in lumbar radicular pain varies. The purpose of this study is to characterize the changes in quantitative sensory testing (QST) phenotypes of subjects and compare the QST characteristics in patients who do respond to treatment of radicular pain with a lumbar epidural steroid injection (ESI). Prospective, observational pilot study. Outpatient pain center. Twenty subjects with a lower extremity (LE) radicular pain who were scheduled to have an ESI were recruited. At the visit prior to and four weeks following an ESI, subjects underwent QST measurements of both the affected LE and the contralateral unaffected UE. Following an ESI, nine subjects reported a greater than 30% reduction in radicular pain and 11 reported a less than 30% reduction in radicular pain. Subjects who had less than 30% pain reduction response (nonresponders) to an ESI had increased pre-injection warm sensation threshold (37.30 °C, SD = 2.51 vs 40.39, SD = 3.36, P = 0.03) and heat pain threshold (47.22 °C, SD = 1.38, vs 48.83 °C, SD = 2.10, P = 0.04). Further, the nonresponders also showed increased pre-injection warm sensation threshold as measured in the difference of warm sensation detection threshold difference in the affected limb and the unaffected arm (2.68 °C, SD = 2.92 vs 5.67 °C, SD = 3.22, P = 0.045). Other QST parameters were not affected. The results show that the nonresponders to ESIs have increased detection threshold to heat pain and warm sensation, suggesting that a preexisting dysfunction in the C fibers in this group of subjects who can be detected by QST. Such altered QST characteristics may prognosticate the response to ESIs.

Pain and psychological characteristics in patellar tendinopathy

Introduction: Patellar tendinopathy (PT) is a common injury in sports and is characterized by persistent pain and interference with physical activity. Evidence from other persistent musculoskeletal pain states has shown alterations in somatosensory profiles implicating central nervous system involvement. The aim was therefore to assess detection and pain thresholds in patients with persistent PT compared with healthy controls. Methods: The following Quantitative Sensory Testing (QST) was performed in 19 people with PT (age 20–45 years; 26% female) and 15 healthy controls (age 21–33 years; 53% female): warmth and cold detection, thermal sensory limen, heat and cold pain, mechanical detection threshold, mechanical pain threshold, mechanical pain sensitivity, dynamic mechanical allodynia, vibration disappearance threshold, wind up ratio and pressure pain threshold (PPT). The assessor was blinded to the participant group. Testing in patients and controls was performed at two standardized locations; over the infra patellar pole (most affected or randomly allocated leg respectively) and the lateral elbow (randomly allocated arm). The VISA-P, Health-related Quality of Life (EQ-5D), the Hospital Anxiety and Depression Scale (HADS), the Active Australia Questionnaire and the Mental Toughness Questionnaire (MTQ-48) were completed by all participants. ANCOVA was performed to compare groups, adjusting for sex, age and BMI. Ordinal data was assessed with non-parametric Mann Whitney U tests. Results: PPT measured at the proximal patellar tendon was significantly lower in the PT group (408.8 kPa) compared to controls (568.5 kPa) after adjusting for sex, age and BMI (P = 0.012). No between-group differences were found for any other QST measures at either the inferior pole or lateral elbow. The PT group had significantly lower quality of life scores (P < 0.001) and significantly higher mental toughness scores (P < 0.05) compared to controls. No differences existed between groups for anxiety, depression and physical activity. Discussion: Significantly lower PPT scores for people with PT compared to healthy controls suggests peripheral mechanical hyperalgesia. The lack of evidence of central sensitization may be different to other tendinopathies. Although people with PT have a lower quality of life, they also seem to be more mentally tough than healthy controls. Further research should elaborate on this personality trait as well as the negative and positive influences it might have on the development and rehabilitation of injuries.

Quantitative sensory testing in Achilles tendinopathy

Introduction: Achilles tendinopathy (AT) is a prevalent injury in the adult population, causing persistent pain and disability. Although, recent literature proposes peripheral and central nervous system alterations as one of the underlying processes of persistent pain in tendinopathies, the evidence in people with AT is limited. The primary aim of this study was to assess differences in detection and pain threshold between people with AT and healthy controls. Methods: Thirty people with a clinical diagnosis of AT and 11 healthy controls were recruited. All participants were free from other musculoskeletal injuries, diabetes or other systemic conditions. Quantitative sensory testing (QST) measures were performed by an assessor blinded to their condition. Testing in patients and controls was performed at two standardized locations: the mid-Achilles tendon (most affected or randomly allocated leg respectively) and the lateral elbow (side randomly selected). We determined thermal detection and pain thresholds, thermal sensory limen, mechanical detection thresholds to von Frey filaments and vibration, mechanical pain thresholds to pinprick stimuli and blunt pressure, stimulus-response-functions for pinprick and dynamic mechanical allodynia (pain to light touch), and wind up ratio using repetitive pinprick stimulation. Participants also completed VISA-A, Health-related Quality of Life (EQ-5D), Hospital Anxiety and Depression Scale (HADS), Active Australia and Mental Toughness (MTQ-48) questionnaires. ANCOVA was performed to compare groups adjusting for sex, age and BMI. Results: There were no significant differences for age and sex between the AT group (mean age 45.7 years, range 21–63, 43% female) and the controls (mean age 40.9 years, range 19–68, 46% female). Body mass index was greater in the AT group (BMI 28.3 kg/m2; SD 5.4) compared to the controls (BMI 23.4 kg/m2; SD 2.7, P < 0.005). Those with AT had an average VISA-A score of 57/100, average duration of symptoms of 38.6 months, present at mid-tendon (73%) or insertional (37%) regions. Quality of life was significantly lower in the AT group (mean: 0.74; SD 0.06) compared to the control group (mean 0.96; SD 0.08, P < 0.001). The AT group did not show significant differences compared to the controls on any of the QST measures at either site. Discussion: Based on the limited sample, this study did not find significant peripheral- or central somatosensory changes in people with AT compared to healthy controls. This is in contrast with other studies that found evidence of peripheral sensitization in people with AT.

Effect of Experimental Periodontal Ligament Pain on Gingival Somatosensory Sensitivity.

To use a randomized, blinded, crossover design to evaluate the possible heterotopic effects of experimental periodontal ligament pain on adjacent gingival somatosensory sensitivity. A total of 12 healthy volunteers (8 female, 4 male; mean age ± standard error in means (SEM): 28 ± 1 years) participated in two randomized experimental quantitative sensory testing (QST) sessions, one in which capsaicin (experimental) was injected into the periodontal ligament and one in which isotonic saline (control) was injected. A total of 13 standardized QST measures were obtained on the buccal attached gingiva of a maxillary central incisor before, immediately after, and 30 minutes after injection of 30 μL of 5% capsaicin or isotonic saline into the periodontal ligament of the same incisor. The injection-evoked pain was evaluated on a 0-10 numeric rating scale (NRS). QST data were analyzed with two-way repeated measurement analysis of variance. Capsaicin injected into the periodontal ligament evoked moderate levels of pain (mean peak NRS ± SEM: capsaicin: 5.5 ± .7; control: 0.6 ± 0.5 [P < .001]). Capsaicin injected into the periodontal ligament significantly modulated gingival somatosensory sensitivity: increased sensitivity to warmth and painful heat stimuli occurred immediately and 30 minutes after the injection (P < .025), whereas decreased sensitivity to both tactile and painful mechanical stimuli (P < .011) occurred immediately after the injection and to painful mechanical stimuli only after 30 minutes (P = .016). No somatosensory changes were detected following the injection of isotonic saline (P > .050). Capsaicin injected into the periodontal ligament caused gain of heterotopic somatosensory sensitivity toward warmth and painful heat stimuli as well as reduction in mechanical sensitivity of the gingiva adjacent to the injected tooth. These findings may have implications for interpretation of somatosensory functions in patients with chronic intraoral pain, where gingival somatosensory profiles similar to those detected after capsaicin injection in the present study may be interpreted as signs of nerve damage.

Using a Standardized Clinical Quantitative Sensory Testing Battery to Judge the Clinical Relevance of Sensory Differences Between Adjacent Body Areas.

Skin sensitivity to sensory stimuli varies among different body areas. A standardized clinical quantitative sensory testing (QST) battery, established for the diagnosis of neuropathic pain, was used to assess whether the magnitude of differences between test sites reaches clinical significance. Ten different sensory QST measures derived from thermal and mechanical stimuli were obtained from 21 healthy volunteers (10 men) and used to create somatosensory profiles bilateral from the dorsum of the hands (the standard area for the assessment of normative values for the upper extremities as proposed by the German Research Network on Neuropathic Pain) and bilateral at volar forearms as a neighboring nonstandard area. The parameters obtained were statistically compared between test sites. Three of the 10 QST parameters differed significantly with respect to the "body area," that is, warmth detection, thermal sensory limen, and mechanical pain thresholds. After z-transformation and interpretation according to the QST battery's standard instructions, 22 abnormal values were obtained at the hand. Applying the same procedure to parameters assessed at the nonstandard site forearm, that is, z-transforming them to the reference values for the hand, 24 measurements values emerged as abnormal, which was not significantly different compared with the hand (P=0.4185). Sensory differences between neighboring body areas are statistically significant, reproducing prior knowledge. This has to be considered in scientific assessments where a small variation of the tested body areas may not be an option. However, the magnitude of these differences was below the difference in sensory parameters that is judged as abnormal, indicating a robustness of the QST instrument against protocol deviations with respect to the test area when using the method of comparison with a 95 % confidence interval of a reference dataset.

Effects of High-Dose Capsaicin on TMD Subjects: A Randomized Clinical Study.

Temporomandibular joint disorder (TMD) is a complex musculoskeletal disorder that presents with pain, limited jaw opening, and abnormal noises in the temporomandibular joint. Despite the significant impact that TMD has in terms of suffering and financial burden, relatively few new treatments have emerged; therefore, development of novel treatments to treat TMD pain remains a high priority. The rationale of this study was to use a double-blind, vehicle-controlled clinical trial to evaluate the effects of a high-concentration (8%) capsaicin cream on TMD. This is based on the hypothesis that targeting TRP vanilloid subfamily member 1 (TRPV1) for pain control may provide a novel method for pain relief in TMD patients. TRPV1 is primarily expressed on a population of nociceptive-specific neurons and provides a candidate target for the development of pain treatments. Capsaicin is the primary agonist for TRPV1 and has been used previously in relatively low doses (0.025% to 0.075%) as a therapeutic for a variety of pain disorders, including postherpetic neuralgia and osteoarthritis; however, analgesic efficacy remains equivocal. TMD and healthy control subjects were assigned to either an active capsaicin or vehicle control group. The treatments were applied for 2 h and then removed. Quantitative sensory testing (QST) was completed prior to drug application (baseline), 2 h after drug application, and 1 wk later. Perceived pain intensity was measured using a visual analog scale (VAS) following capsaicin or vehicle cream application. Significantly lower pain was reported in the week after application in the capsaicin-treated TMD subjects. For QST measures, there was a decreased thermal pain threshold 2 h after capsaicin application for both the control and TMD groups, but this resolved within a week. Capsaicin had no effect on pressure pain threshold or mechanical sensitivity in both TMD and healthy individuals. This study demonstrates that 8% topical capsaicin therapy is a relatively safe, simple, and effective treatment for patients with TMD. Knowledge Transfer Statement: This study evaluated a novel topical capsaicin therapy for reducing orofacial pain. The results of this study can be used to provide another treatment option for patients with TMD.

Effect of medical cannabis on thermal quantitative measurements of pain in patients with Parkinson's disease.

Cannabis can alleviate pain of various etiologies. This study assessed the effect of cannabis on motor symptoms and pain parameters in patients with Parkinson's disease (PD). Twenty patients with PD who were licensed to use cannabis underwent evaluation before and 30min after cannabis consumption and again after long-term use. Motor function was assessed with the Unified PD Rating scale (UPDRS) by two raters, one blinded. Pain was assessed with the Pain Rating Index (PRI) and Visual Analogue Scale (VAS) of the short-form McGill Pain Questionnaire. Thermal quantitative sensory testing (QST) was performed in 18 patients. The two consecutive QST measurements were validated in 12 cannabis-naïve patients with PD. There was a significant decrease from baseline to 30min after cannabis consumption in mean motor UPDRS score (38.1±18 to 30.4±15.6, p<0.0001), total PRI (27±13.5 to 9.7±11, p=0.001), and VAS score (6.4±2.8 to 3.6±3.1, p=0.0005). Mean cold pain threshold decreased significantly in the more affected limb, but only after exclusion of two patients who consumed cannabis by vaporizer rather than smoking (19.5±5.2 to 15.6±8.7°C, p=0.02). After long-term (median 14weeks) exposure, mean heat pain threshold decreased significantly in the more affected limb in all treated patients (43.6±3.5 to 40.9±3.3°C, p=0.05) and in cannabis smokers (43.7±3.6 to 40.3±2.5°C, p=0.008). Cannabis improved motor scores and pain symptoms in PD patients, together with a dissociate effect on heat and cold pain thresholds. Peripheral and central pathways are probably modulated by cannabis. Quantitative sensory test results are significantly altered following cannabis consumption in patients with PD. Cannabis probably acts on pain in PD via peripheral and central pathways.

Prognostic value of quantitative sensory testing in low back pain: a systematic review of the literature.

Quantitative sensory testing (QST) measures have recently been shown to predict outcomes in various musculoskeletal and pain conditions. The aim of this systematic review was to summarize the emerging body of evidence investigating the prognostic value of QST measures in people with low back pain (LBP). The protocol for this review was prospectively registered on the International Prospective Register of Systematic Reviews. An electronic search of six databases was conducted from inception to October 2015. Experts in the field were contacted to retrieve additional unpublished data. Studies were included if they were prospective longitudinal in design, assessed at least one QST measure in people with LBP, assessed LBP status at follow-up, and reported the association of QST data with LBP status at follow-up. Statistical pooling of results was not possible due to heterogeneity between studies. Of 6,408 references screened after duplicates removed, three studies were finally included. None of them reported a significant association between the QST measures assessed and the LBP outcome. Three areas at high risk of bias were identified which potentially compromise the validity of these results. Due to the paucity of available studies and the methodological shortcomings identified, it remains unknown whether QST measures are predictive of outcome in LBP.

Nervous System Sensitization as a Predictor of Outcome in the Treatment of Peripheral Musculoskeletal Conditions: A Systematic Review.

Research suggests that peripheral and central nervous system sensitization can contribute to the overall pain experience in peripheral musculoskeletal (MSK) conditions. It is unclear, however, whether sensitization of the nervous system results in poorer outcomes following the treatment. This systematic review investigated whether nervous system sensitization in peripheral MSK conditions predicts poorer clinical outcomes in response to a surgical or conservative intervention. Four electronic databases were searched to identify the relevant studies. Eligible studies had a prospective design, with a follow-up assessing the outcome in terms of pain or disability. Studies that used baseline indices of nervous system sensitization were included, such as quantitative sensory testing (QST) or questionnaires that measured centrally mediated symptoms. Thirteen studies met the inclusion criteria, of which six were at a high risk of bias. The peripheral MSK conditions investigated were knee and hip osteoarthritis, shoulder pain, and elbow tendinopathy. QST parameters indicative of sensitization (lower electrical pain thresholds, cold hyperalgesia, enhanced temporal summation, lower punctate sharpness thresholds) were associated with negative outcome (more pain or disability) in 5 small exploratory studies. Larger studies that accounted for multiple confounders in design and analysis did not support a predictive relationship between QST parameters and outcome. Two studies used self-report measures to capture comorbid centrally mediated symptoms, and found higher questionnaire scores were independently predictive of more persistent pain following a total joint arthroplasty. This systematic review found insufficient evidence to support an independent predictive relationship between QST measures of nervous system sensitization and treatment outcome. Self-report measures demonstrated better predictive ability. Further high-quality prognostic research is warranted.

Experimental pain phenotyping in community-dwelling individuals with knee osteoarthritis.

Pain among individuals with knee osteoarthritis (OA) is associated with significant disability in older adults, and recent evidence demonstrates enhanced experimental pain sensitivity. Although previous research showed considerable heterogeneity in the OA clinical pain presentation, less is known regarding the variability in responses to experimental pain. The present study included individuals with knee OA (n = 292) who participated in the Understanding Pain and Limitations in Osteoarthritic Disease study and completed demographic and psychological questionnaires followed by a multimodal quantitative sensory testing (QST) session. Quantitative sensory testing measures were subjected to variable reduction procedures to derive pain sensitivity index scores, which in turn were entered into a cluster analysis. Five clusters were significantly different across all pain sensitivity index variables (P < 0.001) and were characterized by: (1) low pain sensitivity to pressure pain (N = 39); (2) average pain sensitivity across most modalities (N = 88); (3) high temporal summation of punctate pain (N = 38); (4) high cold pain sensitivity (N = 80); and (5) high sensitivity to heat pain and temporal summation of heat pain (N = 41). Clusters differed significantly by race, gender, somatic reactivity, and catastrophizing (P < 0.05). Our findings support the notion that there are distinct subgroups or phenotypes based on experimental pain sensitivity in community-dwelling older adults with knee OA, expanding previous findings of similar cluster characterizations in healthy adults. Future research is needed to further understand the pathophysiological mechanisms underlying pain within these subgroups, which may be of added value in tailoring effective treatments for people with OA.

Pain sensitivity profiles in patients with advanced knee osteoarthritis.

The development of patient profiles to subgroup individuals on a variety of variables has gained attention as a potential means to better inform clinical decision making. Patterns of pain sensitivity response specific to quantitative sensory testing (QST) modality have been demonstrated in healthy subjects. It has not been determined whether these patterns persist in a knee osteoarthritis population. In a sample of 218 participants, 19 QST measures along with pain, psychological factors, self-reported function, and quality of life were assessed before total knee arthroplasty. Component analysis was used to identify commonalities across the 19 QST assessments to produce standardized pain sensitivity factors. Cluster analysis then grouped individuals who exhibited similar patterns of standardized pain sensitivity component scores. The QST resulted in 4 pain sensitivity components: heat, punctate, temporal summation, and pressure. Cluster analysis resulted in 5 pain sensitivity profiles: a "low pressure pain" group, an "average pain" group, and 3 "high pain" sensitivity groups who were sensitive to different modalities (punctate, heat, and temporal summation). Pain and function differed between pain sensitivity profiles, along with sex distribution; however, no differences in osteoarthritis grade, medication use, or psychological traits were found. Residualizing QST data by age and sex resulted in similar components and pain sensitivity profiles. Furthermore, these profiles are surprisingly similar to those reported in healthy populations, which suggests that individual differences in pain sensitivity are a robust finding even in an older population with significant disease.

Quantitative Sensory Testing in Chronic Musculoskeletal Pain.

In recent years, several published articles have demonstrated that quantitative sensory testing (QST) is useful in the analysis of musculoskeletal pain disorders. Based on the evidence from these studies, it is assumed that QST might be a useful tool in the analysis of the pathogenesis, classification, differential diagnosis, and prognosis of chronic musculoskeletal pain. The objective of this paper is to discuss measurement properties of QST and potentials research and clinical applications in musculoskeletal pain. This is a review of the current knowledge base on QST as it relates to musculoskeletal pain disorders. We based our summary on articles retrieved from Ovid MEDLINE (1946 to present) including EMBASE, AMED, and PsycINFO databases to search for all published literature focused on QST and musculoskeletal pain. QST has been shown to be related to neural sensitivity in musculoskeletal pain. QST measurement properties have been evaluated for multiple sensory evaluation modalities and protocols with no clear superior instrument or test protocol. The research evidence is incomplete, but suggests potential clinical benefits for predicting outcomes and subtyping pain. Threshold detection testing is commonly used to quantify sensory loss or gain, in current practice and has shown moderate reliability. Intensity/magnitude rating can be assessed on a wide range of rating scales and may be more useful for pain rating in a clinical context. Threshold detection-based testing and intensity/magnitude rating-based testing can be combined to determine pain threshold in clinical evaluation. Musculoskeletal pain management may benefit from treatment algorithms that consider mechanism, pain quality, or neurophysiological correlates. Non-invasive QST may be helpful to find sensory array of altered nociceptive process. Due to the diverse etiopathogenetic basis of musculoskeletal pain disorders, a broad range of reliable and valid QST tests may be needed to analyze the various disease entities.

Quantitative sensory testing in type 1 diabetic patients with mild to severe diabetic neuropathy

Background: Small nerve fibre damage has been shown to precede large fibre damage and represents the early stage for diabetic neuropathy (DPN). Aims: To assess small nerve fibre deficit in patients with mild to severe DPN using quantitative sensory testing (QST) and to correlate QST findings with other neuropathy assessment measures in patients with DPN. Materials and Methods: Seventy-nine diabetic patients (49 with and 30 without diabetic neuropathy) and 35 healthy volunteers underwent neuropathy assessment. The evaluation comprised neuropathy symptoms profile, modified neuropathy disability score (NDS), quantitative sensory testing (QST) in form of cold and warm thresholds, vibration pressure threshold (VPT), nerve conduction studies (NCS), deep breathing heart rate variability (DB-HRV), and Neuropad staining scores. Patients were also stratified by their NDS scores into mild, moderate and severe DPN. Measures of QST were compared among various grades of DPN severity and correlated with other clinical and neurophysiological tests. Results: Patients with DPN demonstrated higher vibration perception (P<0.001) and warm (P<0.001) thresholds and lower cold threshold (P<0.001) and these QST abnormalities related directly to the grade of DPN severity. Measures of QST also correlated with those of nerve conduction studies (r range 0.54-0.68) and autonomic function assessment(r range 0.33-0.48). Conclusion: Quantitative sensory testing can identify small nerve fibres impairment which could represent the early stage of diabetic neuropathy and hence the optimal period for intervention.

Quantitative sensory testing in type 1 diabetic patients with painful and painless diabetic neuropathy

The mechanism underlying the development of painful diabetic neuropathy (DN) is unknown. The aim of this study was to compare quantitative sensory testing (QST) characteristics of patients with painful and painless DN and to correlate QST measures with DN pain. Fifty type 1 diabetic patients with DN (30 with painful DN and 20 with painless DN) and 32 age-matched non-diabetic controls were included in this study. For all patients and controls, a detailed assessment of DN was performed which comprised McGill visual analogue scale (McGill VAS) for pain, neuropathy symptom profile and neuropathy disability score (NDS), quantitative sensory testing in form of cold, warm and vibration perception thresholds, nerve conduction studies (NCS), deep-breathing hear rate variability and Neuropad staining scores. Measures of QST, NCS and DB-HRV were correlated with McGill VAS for pain. There were no significant differences in cold, warm and vibration perception thresholds, NCS, DB-HRV and Neuropad scores between patients with painful and painless DN. Cold (r=-0.57, P=0.005), warm (r=0.47, P=0.026) and DB-HRV (r=0.50, P=0.023), however, correlated significantly with McGill VAS scores of pain. In conclusion, Quantitative sensory testing is a helpful tool to identify small nerve fibres damage of DN, correlates with pain intensity but cannot differentiate between painful and painless DN. Both central and peripheral neural injury could be implicated in the genesis of DN pain.

Differences in quantitative sensory testing measures in patients with poor outcomes following total knee replacement

Differences in quantitative sensory testing measures in patients with poor outcomes following total knee replacement