Examining somatosensory function by age, testing site, and modality

Background and ObjectivesSomatosensory function is critical for successful aging. Prior studies have shown declines in somatosensory function with age; however, this may be affected by testing site, modality, and biobehavioral factors. While somatosensory function declines are associated with peripheral nervous system degradation, little is known regarding correlates with the central nervous system and brain structure in particular. The objectives of this study were to examine age-related declines in somatosensory function using innocuous and noxious stimuli, across 2 anatomical testing sites, with considerations for affect and cognitive function, and associations between somatosensory function and brain structure in older adults.Research Design and MethodsA cross-sectional analysis included 84 “younger” (n = 22, age range: 19–24 years) and “older” (n = 62, age range: 60–94 years) healthy adults who participated in the Neuromodulatory Examination of Pain and Mobility Across the Lifespan study. Participants were assessed on measures of somatosensory function (quantitative sensory testing), at 2 sites (metatarsal and thenar) using standardized procedures, and completed cognitive and psychological function measures and structural magnetic resonance imaging.ResultsSignificant age × test site interaction effects were observed for warmth detection (p = .018, 0.10) and heat pain thresholds (p = .014, 0.12). Main age effects were observed for mechanical, vibratory, cold, and warmth detection thresholds (ps < .05), with older adults displaying a loss of sensory function. Significant associations between somatosensory function and brain gray matter structure emerged in the right occipital region, the right temporal region, and the left pericallosum.Discussion and ImplicationsOur findings indicate healthy older adults display alterations in sensory responses to innocuous and noxious stimuli compared to younger adults and, furthermore, these alterations are uniquely affected by anatomical site. These findings suggest a nonuniform decline in somatosensation in older adults, which may represent peripheral and central nervous system alterations part of aging processes.

An investigation of gender-dependent perception of thermal and pain: a quantitative sensory testing study

ABSTRACTBackground and AimsSkin biopsies are the primary diagnostic test for small fiber neuropathy, but recently corneal confocal microscopy (CCM) has been developed as an alternative. We compared the correlations of each of these morphometric assessments with peripheral nerve function evaluated through comprehensive quantitative sensory testing (QST) in a mixed etiology polyneuropathy cohort.MethodsCCM and skin biopsies were performed in a prospective cohort of unselected patients undergoing polyneuropathy diagnostic work‐up. We used predefined criteria to identify patients with small or mixed fiber neuropathy. The correlations between corneal nerve fiber density (CNFD), fiber length (CNFL), branch density (CNBD), and tortuosity (CNFT) and the intraepidermal nerve fiber density (IENFD) at the distal leg and the results of QST at the foot were determined.ResultsTwo‐hundred and forty‐four patients were included in the analysis. CNFD was negligibly correlated with warm detection threshold (WDT) (r = −0.15; p = 0.023), while there was no statistically significant correlation with other QST measures. There were no statistically significant correlations between neither CNFL nor CNBD and any of the QST measures. CNFT correlated negligibly with WDT (r = 0.17; p = 0.008) and vibration detection threshold (VDT) (r = −0.13; p = 0.044). IENFD correlated moderately with WDT (r = −0.33; p < 0.0001) and mechanical pain threshold (r = −0.37; p < 0.0001) and weakly with cold detection threshold (r = 0.21; p = 0.0008), mechanical detection threshold (r = −0.21; p = 0.0008) and VDT (r = 0.23; p = 0.0004).InterpretationIENFD correlated better with small and large fiber function at the foot than CCM measures in patients with mixed etiology polyneuropathy. Longitudinal studies are needed to assess the clinical utility for neuropathy progression.

In order to distinguish the grades of breast pain with a quantitative index, the detection and pain thresholds were measured with the technique of TSA (Thermal Sensory Analysis) on patients with breast pain. We aimed to explore whether TSA could be used to predicate the degree of breast pain as an objective indicator or not. Thirtytwo female outpatients with breast pain were included in the study by inclusion criteria. A total of sixtyfour breasts were measured. The cold pain threshold (CPT), cold detection threshold (CDT), warm detection threshold (WDT) and heat pain threshold (HPT) were measured at the following five points of both sides: neck, shoulder, axilla, back and super ior lateral quadrant of breast. The sixtyfour breasts were devided into three groups: Group A consisted of 29 breasts that have breast pain grade from 0 to 1 (No pain at that time); Group B consisted of 20 breasts that have breast pain grade from 2 to 4 (Pain exist, but participant can’t give it an explicit score); Group C consisted of 15 breasts that have breast pain grade from 5 to 7. Statistic analysis was performed by SPSS 20.0 to compare the means and SD. Variance for each threshold at each site was expressed as Coefficient of Variation percentage (CV%), using the standard deviation (SD) divided by the meanx100. On every sites, group B has the highest value of WDT and HPT. And expect the site of axilla, group C has higher values than group A of WDT and HPT. On the site of breast, the values of CPT and CDT have the trend to increase from group A to group C. But the differences in groups were without statistically significant differences (p>0.2). The CV% of HPT and WDT are lowest and near to each other, and CPT has the highest value of CV%. Breast pain can not only reduce the sensibility of warm detection and heat pain of breast, but also the sites close to breast. Oppositely, breast pain can enhance the sensibility of cold detection and cold pain of breast. But C PT has the highest value of CV%, this may means CPT has poor reliability due to wide variance.

ObjectiveTo investigate the relationship between tendon structural changes determined by static ultrasound images (US) and sensory changes using quantitative sensory testing (QST), and clinical measures in lateral epicondylalgia.Materials and methodsBoth elbows of 66 adult participants with a clinical diagnosis of lateral epicondylalgia were investigated. Using a standardised ultrasound image rating scale, common extensor hypoechogenicity, heterogenicity, neovascularity, and bony abnormalities at the enthesis were scored, and tendon thickness (longitudinal and transverse plane) was measured by a trained assessor. Sensory measures of pressure, heat and cold pain thresholds and vibration detection threshold were recorded. Pain and function were assessed using the patient-rated tennis elbow (PRTEE), pain-free grip strength, pain visual analog scale (PVAS) and quality of life (EuroQoL EQ -5D). Univariate and multivariate linear regression analyses were used to explore the association between tendon structural, sensory and clinical variables which were adjusted for age, gender and duration of symptoms.ResultsA negative correlation was identified between the presence of neovascularity and cold pain threshold (P = 0.015). Multiple regression analyses revealed that a combination of female gender (P = 0.044) and transverse tendon thickness (P = 0.010) were significantly associated with vibration detection threshold in affected elbows, while gender (P = 0.012) and total ultrasound scale score (P = 0.024) were significantly associated with heat pain threshold and vibration detection threshold in unaffected elbows. Heat pain threshold and gender were significantly associated with pain and disability (PRTEE; P < 0.001), and pain-free grip strength (P < 0.001) respectively, in the affected elbows.ConclusionGenerally, structural and sensory measures were weakly correlated. However, neovascularity and transverse tendon thickness may be related to sensory system changes in LE.

Background: Many patients referred for physical therapy have pain and somatosensory problems. Thermal quantitative sensory testing (QST) is used for assessing somatosensory function. Method of limits (MLI) and method of levels (MLE) are two commonly measurement methods used for thermal QST. A good measurement method for clinical application should be convenient and reliable. The purpose of this study was to compare the acceptability and reliability of the MLI and MLE. Methods: Twenty-eight healthy adults (14 males and 14 females) participated in a thermal QST test retest study. The types of the thermal QSTs included the Cold Detection Threshold (CDT), Warm Detection Threshold (WDT), Cold Pain Threshold (CPT), and Heat Pain Threshold (HPT). Participants were examined with thermal QST using the two methods (MLI and MLE), and then re-examined after one week. Both the relative reliability and absolute reliability were estimated. Results: The acceptability was better in the MLI than in the MLE. Many trials of the MLE was needed (the mean number of trials = 12.2; range from 7 to 27 trials). The relative reliability of the MLI and MLE were similar; the range of intraclass correlation coefficient were 0.65 to 0.88 and 0.69 to 0.86 for the MLI and MLE, respectively. However, the absolute reliability of the CDT, WDT, and HPT on the MLE were not as accurate as those on the MLI. Conclusion: When we compared the acceptability and reliability, the MLI was superior to the MLE. The MLI is recommended as useful method for measuring thermal and pain thresholds.

BackgroundMany studies show an effectiveness of hypnotic analgesia. It has been discussed whether the analgesic effect is mainly caused by the relaxation that is concomitant to hypnosis. This study was designed to evaluate the effects of hypnotic relaxation suggestion on different somatosensory detection and pain thresholds.MethodsQuantitative sensory testing (QST) measurements were performed before and during hypnosis in twenty-three healthy subjects on the dorsum of the right hand. Paired t-test was used to compare threshold changes. The influence of hypnotic susceptibility was evaluated by calculating correlation coefficients for threshold changes and hypnotic susceptibility (Harvard group scale).ResultsDuring hypnosis significantly changed somatosensory thresholds (reduced function) were observed for the following sensory detection thresholds: Cold Detection Threshold (CDT), Warm Detection Threshold (WDT), Thermal Sensory Limen (TSL) and Mechanical Detection Threshold (MDT). The only unchanged sensory detection threshold was Vibration Detection Threshold (VDT). No significant changes were observed for the determined pain detection thresholds (Cold Pain Thresholds, Heat Pain Thresholds, Mechanical Pain Sensitivity, Dynamic Mechanical Allodynia, Wind-up Ratio and Pressure Pain Threshold). No correlation of hypnotic susceptibility and threshold changes were detected.ConclusionHypnotic relaxation without a specific analgesic suggestion results in thermal and mechanical detection, but not pain threshold changes. We thus conclude that a relaxation suggestion has no genuine effect on sensory pain thresholds.Trial RegistrationClinicalTrials.gov, Identifier:NCT02261155 (9th October 2014).

Low-level laser therapy (LLLT) may have an effect on the pain associated with orthodontic treatment. The aim of this study was to evaluate the effect of LLLT on pain and somatosensory sensitization induced by orthodontic treatment. Forty individuals (12–33 years old; mean ± standard deviations: 20.8 ± 5.9 years) scheduled to receive orthodontic treatment were randomly divided into a laser group (LG) or a placebo group (PG) (1:1). The LG received LLLT (810-nm gallium-aluminium-arsenic diode laser in continuous mode with the power set at 400 mW, 2 J·cm–2) at 0 h, 2 h, 24 h, 4 d, and 7 d after treatment, and the PG received inactive treatment at the same time points. In both groups, the non-treated side served as a control. A numerical rating scale (NRS) of pain, pressure pain thresholds (PPTs), cold detection thresholds (CDTs), warmth detection thresholds (WDTs), cold pain thresholds (CPTs), and heat pain thresholds (HPTs) were tested on both sides at the gingiva and canine tooth and on the hand. The data were analysed by a repeated measures analysis of variance (ANOVA). The NRS pain scores were significantly lower in the LG group (P = 0.01). The CDTs, CPTs, WDTs, HPTs, and PPTs at the gingiva and the PPTs at the canine tooth were significantly less sensitive on the treatment side of the LG compared with that of the PG (P < 0.033). The parameters tested also showed significantly less sensitivity on the non-treatment side of the LG compared to that of the PG (P < 0.043). There were no differences between the groups for any quantitative sensory testing (QST) measures of the hand. The application of LLLT appears to reduce the pain and sensitivity of the tooth and gingiva associated with orthodontic treatment and may have contralateral effects within the trigeminal system but no generalized QST effects. Thus, the present study indicated a significant analgesia effect of LLLT application during orthodontic treatment. Further clinical applications are suggested.

Somatosensory changes after sagittal split ramus osteotomy (SSRO) have not been fully studied in Chinese patients by the latest technologies. To provide a comprehensive analysis of somatosensory function at the lower lip and chin at different time points following SSRO in a Chinese population. A total of 22 patients (18-27years; nine men) with skeletal III malocclusion and scheduled for SSRO were recruited. Quantitative sensory testing (QST) was performed at pre-operation (baseline), 1week (1W), 1, 3 and 6months (1M, 3M, 6M) post-operatively. Cold detection threshold (CDT), warm detection threshold (WDT), cold pain threshold (CPT), heat pain threshold (HPT), mechanical detection threshold (MDT), mechanical pain threshold (MPT), pressure pain threshold (PPT) and two-point discrimination threshold (2PD) were tested at the lower lip and chin. Except for PPT at both test sides at 1W and 1M, all QST values indicated a significantly reduced sensitivity (p<.05). All values had returned to baseline values at 3M with exception of HPT at the right chin which, however, had recovered at 6M (p>.05). Somatosensory function at the lower lip and chin appears to be fully recovered in the majority of young Chinese adults 6months after SSRO for skeletal class III malocclusion.

IntroductionThis protocol describes the objective and methods of a systematic review of the association between quantitative sensory testing (QST) measures and pain intensity or disability in paediatric chronic pain (PCP)....

Introduction Sleep plays a pivotal role in the central nervous system’s ability to process and integrate sensory information. Disruptions in sleep architecture, such as those seen in insomnia, can impair nociceptive processing and alter sensory perception, thereby influencing pain modulation. Quantitative Sensory Testing (QST) provides a standardized methodology for assessing sensory processing and pain phenotyping by measuring thresholds for detecting and tolerating thermal stimuli, which are often dysregulated in insomnia. Methods This observational study includes 6 patients diagnosed with chronic insomnia and 6 age- and sex-matched healthy controls. The parameters evaluated using QST were: warm detection threshold, cold detection threshold, hot pain threshold, cold pain threshold, hot pain tolerance threshold, and cold pain tolerance threshold (°C). Results Patients with insomnia demonstrated significantly higher warm detection thresholds (p=0.0008) and cold detection thresholds (p=0.02) compared to controls. The mean hot pain threshold in insomnia patients was 43.73°C, significantly higher than 38.54°C in controls (p=0.0012). Similarly, cold pain thresholds were elevated in insomnia patients (p=0.002). Cold pain tolerance thresholds were markedly higher in the insomnia cohort (p=0.0001). However, no statistically significant difference was observed in hot pain tolerance thresholds between the two groups. Conclusion The findings indicate attenuated sensory responsiveness in individuals with insomnia. Chronic insomnia is associated with dysregulation of the central pain modulation systems, particularly within the descending inhibitory pathways originating in the brainstem and modulated by the periaqueductal gray (PAG) and rostroventromedial medulla (RVM). Insomnia may impair the release of endogenous opioids and neurotransmitters like serotonin and norepinephrine, reducing the efficiency of descending pain inhibition and altering thermal pain thresholds. Support (if any)

To compare somatosensory function profiles and psychologic factors in patients with primary burning mouth syndrome (BMS) and healthy controls and to evaluate correlations of subjective pain ratings with somatosensory and psychologic parameters. A quantitative sensory testing (QST) protocol-including cold detection threshold (CDT), warmth detection threshold (WDT), thermal sensory limen (TSL), paradoxical heat sensation (PHS), cold pain threshold (CPT), heat pain threshold (HPT), mechanical pain threshold (MPT), wind-up ratio (WUR), and pressure pain threshold (PPT)-was performed at the oral mucosa of the tongue, buccal, and palatal sites in 30 Chinese patients (25 women and 5 men, mean age 50.9 ± 9.2 years) with primary BMS and in 18 age- and gender-matched healthy controls (15 women and 3 men, mean age 53.2 ± 7.0 years). For each BMS patient, z scores and loss/gain scores were computed. Psychologic status was evaluated in both groups using the Self-Rating Anxiety Scale and Self-Rating Depression Scale. Correlations of BMS patients' subjective pain ratings with somatosensory and psychologic profiles were assessed with the use of Pearson or Spearman correlations and multiple linear regression. In BMS patients, 53.3% had somatosensory abnormalities according to z scores vs 22.2% of healthy controls (P = .033). The abnormalities in BMS patients were somatosensory loss to thermal nonnoxious stimuli (TSL = 20.0%, CDT = 13.3%, WDT = 13.3%), mechanical pressure stimuli (PPT = 16.7%), pinprick stimuli (MPT = 6.7%), and thermal pain stimuli (CPT = 3.3%), and somatosensory gain to repetitive pinprick stimuli (WUR = 6.7%), pressure stimuli (PPT = 6.7%), and thermal pain stimuli (HPT = 3.3%). The most frequent loss/gain score was 13.3% for loss of thermal somatosensory function with no somatosensory gain; 13.3% for loss of thermal and mechanical somatosensory function with no somatosensory gain; and 13.3% for gain of mechanical somatosensory function with no somatosensory loss. Mild elevations in anxiety scores were seen in 30% of the BMS patients, and 50% and 36.7% had mild and moderate elevations, respectively, in depression scores. No anxiety or depression was detected in the control group. QST results, but not psychologic scores, were significantly correlated with patients' subjective pain ratings (PHS, Spearman coefficient -0.384, P = .029; CPT, Pearson coefficient -0.370, P = .034; MPT, Pearson coefficient -0.376, P = .032; PPT, Pearson coefficient 0.363, P = .037). The present findings documented distinct differences in somatosensory function in patients with primary BMS compared to controls, indicating a complex pathophysiology and interaction between impairments in nociceptive processing and psychologic functioning.

Few studies used thermal quantitative sensory testing to assess the effects of repeated capsaicin gel administration in the oral cavity. This study aimed to investigate thermal sensory and pain thresholds before and after repeated capsaicin gel administration. Ten healthy females (22 ± 2 years) applied a capsaicin gel on the gingival mucosa twice daily for 14 days, and heat pain threshold, warm detection threshold, cold pain threshold, and cold detection threshold were assessed on the oral mucosa. Measurements were performed before and after the 14 days and were compared to a control sample (n = 10, all females, 23 ± 3 years). Capsaicin increased heat pain threshold in the anterior maxilla by 2.9°C (95% CI: 1.6-4.2) (p < 0.001) and in the anterior mandible by 2.2°C (95% CI: 1.0-3.4) (p = 0.001), similar to warm detection threshold that increased by Δ1.1°C (95% CI: 0.3-1.9) (p = 0.009). No significant changes were found in the controls. These findings encourage the use of thermal quantitative sensory testing in the oral cavity to assess thermal sensation, which might be useful for assessing the effects of therapies aimed at reducing pain.

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.

Chronic pain is a complex phenomenon that is thought to affect between 17 and 22% of the Australian population. The complexities of chronic pain and the many different contributing factors to this condition, makes the relief of the symptomatic experience of pain difficult in many cases. Although there are a wide variety of treatment options available with varying degrees of invasiveness, often these options alone and in combination do not provide adequate pain relief for chronic pain sufferers. There is some evidence that repetitive transcranial magnetic stimulation (rTMS) can alleviate the experience of chronic pain in individuals with medication-resistant chronic pain. The mechanisms by which rTMS may induce pain relief, however, are unknown. Consequently, there is a need to further explore the underlying mechanisms contributing to the analgesic effect that rTMS displays. The present research examines the ability of TMS to directly influence peripheral sensations. The first two studies compared the effects of a single session of low frequency (1 Hz) TMS and high frequency (20 Hz) rTMS on thermal sensory thresholds in healthy individuals. High frequency rTMS was found to produce greater alterations in sensory thresholds than low frequency rTMS. A third study was carried out examining the effect of a single session of high frequency (20 Hz) rTMS on the sensory thresholds of individuals suffering from chronic pain and to measure rTMS-induced changes in their experience of pain. Overall, this research revealed a limited degree of sensory alteration following low frequency rTMS in which only cold detection thresholds were significantly modified. High frequency rTMS, however, significantly altered cold detection and pain thresholds for healthy individuals, and cold detection, pain and heat pain thresholds were significantly altered for individuals suffering from chronic pain. In addition, individuals suffering from chronic pain reported a significant reduction in their experience of pain following high frequency rTMS. The finding that rTMS can have a direct effect on sensory thresholds has implications for the therapeutic use of rTMS in the relief of chronic pain and provides scope for further investigation into the long-term effects of these alterations and the use of multiple sessions of rTMS in reducing the experience of chronic pain.