Preoperative pain sensitivity and its correlation with postoperative acute and chronic pain: a systematic review and meta-analysis.

BACKGROUND: Preoperative pain sensitivity (PPS) can be associated with postsurgical pain. However, estimates of this association are scarce. Confirming this correlation is essential to identifying patients at high risk for severe postoperative pain and for developing analgesic strategy. This systematic review and meta-analysis summarises PPS and assessed its correlation with postoperative pain. METHODS: PubMed, Scopus, Cochrane Library, and PsycINFO were searched up to October 1, 2023, for studies reporting the association between PPS and postsurgical pain. Two authors abstracted estimates of the effect of each method independently. A random-effects model was used to combine data. Subgroup analyses were performed to investigate the effect of pain types and surgical procedures on outcomes. RESULTS: A total of 70 prospective observational studies were included. A meta-analysis of 50 studies was performed. Postoperative pain was negatively associated with pressure pain threshold (PPT; r=-0.15, 95% confidence interval [CI] -0.23 to -0.07]) and electrical pain threshold (EPT; r=-0.28, 95% CI -0.42 to -0.14), but positively correlated with temporal summation of pain (TSP; r=0.21, 95% CI 0.12-0.30) and Pain Sensitivity Questionnaire (PSQ; r=0.25, 95% CI 0.13-0.37). Subgroup analysis showed that only TSP was associated with acute and chronic postoperative pain, whereas PPT, EPT, and PSQ were only associated with acute pain. A multilevel (three-level) meta-analysis showed that PSQ was not associated with postoperative pain. CONCLUSIONS: Lower PPT and EPT, and higher TSP are associated with acute postoperative pain while only TSP is associated with chronic postoperative pain. Patients with abnormal preoperative pain sensitivity should be identified by clinicians to adopt early interventions for effective analgesia. SYSTEMATIC REVIEW PROTOCOL: PROSPERO (CRD42023465727).

Phenotypical characterization of exteroceptive sensation and pain symptoms on diabetic patients.

BACKGROUD: Diabetic neuropathy (DN) is one of the most common complications of diabetes, affecting about half of individuals with the disease. Among the various symptoms of DN, the development of chronic pain stands out and manifests as exacerbated responses to sensorial stimuli. The conventional clinical treatments used for general neuropathy and associated painful symptoms, still brings uncomplete and unsatisfactory pain relief. Patients with neuropathic pain syndromes are heterogeneous. They present with a variety of sensory symptoms and pain qualities which difficult the correct diagnosis of sensory comorbidities and consequently, the appropriate chronic pain management. AIMS: Herein, we aimed to demonstrate the existence of different sensory profiles on diabetic patients by investigating epidemiological and clinical data on the symptomatology of a group of patients with DN. METHODS: This is a longitudinal and observational study, with a sample of 57 volunteers diagnosed with diabetes from outpatient day clinic of Hospital Universitário of the University of São Paulo-Brazil. After being invited and signed the Informed Consent Form (ICF), patients were submitted to clinical evaluation and filled out pain and quality of life questionnaires. They also performed quantitative sensory test (QST) and underwent skin biopsy for correlation with cutaneous neuropathology. RESULTS: Data demonstrate that 70% of the studied sample presented some type of pain, manifesting in a neuropathic or nociceptive way, what has a negative impact on the life of patients with DM. We also demonstrated a positive association between pain and anxiety and depression, in addition to pain catastrophic thoughts. Three distinct profiles were identified in the sample, separated according to the symptoms of pain: (i) subjects without pain; (ii) with mild or moderate pain; (iii) subjects with severe pain. We also identified through skin biopsy that diabetic patients presented advanced sensory impairment, as a consequence of the degeneration of the myelinated and unmyelinated peripheral fibers. This study characterized the painful symptoms and exteroceptive sensation profile in these diabetic patients, associated to a considerable level of sensory degeneration, indicating, and reinforcing the importance of the long-term clinical monitoring of individuals diagnosed with DM, regarding their symptom profiles and exteroceptive sensitivity.

The impact of scrambler therapy on pain and quality of life for chemotherapy-induced peripheral neuropathy: A pilot study.

BACKGROUND: Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating disturbance among patients who received chemotherapy, with no effective treatment available. Scrambler therapy (ST) is a noninvasive treatment capable of improving multiple quality-of-life symptoms beyond pain. We aimed to evaluate the efficacy of ST for pain and nonpain symptoms related to CIPN. METHODS: Ten patients with moderate to severe CIPN symptoms for >3 months were enrolled in a single-arm trial of ST for 10 daily sessions. CIPN-related symptoms were measured throughout the treatment period and up to 6 months thereafter. RESULTS: The worst pain was reduced by 6 months (p = 0.0039). QST demonstrated the greatest improvement in pressure of 60 g (p = 0.308, Cohen's d = 0.42) and cold temperature threshold of 2.5°C (p = 0.9375, Cohen's d = 0.51) in the gastrocnemius area. Symptoms of numbness, tingling, trouble walking, and disturbed sleep had significant improvements at 6 months. Pain medication use decreased by 70% at the end of treatment and by 42% at 6 months. Patient satisfaction was high (82%) and no adverse events with ST treatment were reported. CONCLUSIONS: The results of this pilot trial support the use of ST by demonstrating improvement in multiple domains of quality of life for CIPN patients during an extended follow-up of 6 months. However, further large-scale studies are needed to confirm our findings.

Site matters: Central neuropathic pain characteristics and somatosensory findings after brain and spinal cord lesions.

BACKGROUND: It is unknown if different etiologies or lesion topographies influence central neuropathic pain (CNP) clinical manifestation. METHODS: We explored the symptom-somatosensory profile relationships in CNP patients with different types of lesions to the central nervous system to gain insight into CNP mechanisms. We compared the CNP profile through pain descriptors, standardized bedside examination, and quantitative sensory test in two different etiologies with segregated lesion locations: the brain, central poststroke pain (CPSP, n = 39), and the spinal cord central pain due to spinal cord injury (CPSCI, n = 40) in neuromyelitis optica. RESULTS: Results are expressed as median (25th to 75th percentiles). CPSP presented higher evoked and paroxysmal pain scores compared to CPSCI (p < 0.001), and lower cold thermal limen (5.6°C [0.0-12.9]) compared to CPSCI (20.0°C [4.2-22.9]; p = 0.004). CPSCI also had higher mechanical pain thresholds (784.5 mN [255.0-1078.0]) compared to CPSP (235.2 mN [81.4-1078.0], p = 0.006) and higher mechanical detection threshold compared to control areas (2.7 [1.5-6.2] vs. 1.0 [1.0-3.3], p = 0.007). Evoked pain scores negatively correlated with mechanical pain thresholds (r = -0.38, p < 0.001) and wind-up ratio (r = -0.57, p < 0.001). CONCLUSIONS: CNP of different etiologies may present different pain descriptors and somatosensory profiles, which is likely due to injury site differences within the neuroaxis. This information may help better design phenotype mechanism correlations and impact trial designs for the main etiologies of CNP, namely stroke and spinal cord lesions. This study provides evidence that topography may influence pain symptoms and sensory profile. The findings suggest that CNP mechanisms might vary according to pain etiology or lesion topography, impacting future mechanism-based treatment choices.

Association between pelvic pain bothersomeness and pain sensitivity: A community-based cross-sectional study of young adult females in the Raine Study.

OBJECTIVE: Pelvic pain has been associated with augmented nociceptive processing, but large studies controlling for multiple potential confounding factors are lacking. This study investigated the association between pelvic pain bothersomeness and pain sensitivity in young adult women, accounting for potential confounding factors. DESIGN: Cross-sectional study. SETTING: Community-dwelling sample. POPULATION: The Raine Study Gen2-22 year follow-up (n = 475). MAIN OUTCOME MEASURES: The experience of bothersomeness related to pelvic pain was determined from a question in the Urogenital Distress Inventory short form. Pain sensitivity was measured using pressure pain and cold pain thresholds. Potential confounding factors included ethnicity, marital status, highest level of education, income, waist-hip ratio, level of activity, sleep quality, smoking, comorbidity history, C-reactive protein level, musculoskeletal pain experience and psychological distress. RESULTS: Three hundred and sixty-two women (76.2%) reported no pelvic pain bothersomeness, 74 (15.6%) reported mild pelvic pain bothersomeness and 39 (8.2%) reported moderate-severe pelvic pain bothersomeness. After adjusting for marital status (and test site), moderate-severe pelvic pain bothersomeness was associated with a lower pressure pain threshold (i.e. greater pressure pain sensitivity) (coefficient -51.46, 95% CI -98.06 to -4.86, p = 0.030). After adjusting for smoking, moderate-severe pelvic pain bothersomeness was also associated with a higher cold pain threshold (i.e. greater cold pain sensitivity) (coefficient 4.35, 95% CI 0.90-7.79, p = 0.014). CONCLUSIONS: This study suggests augmented nociceptive processing as a contributing factor in pelvic pain bothersomeness for some women. Thorough assessment of women who present clinically with pelvic pain should consider pain sensitivity as a potential contributing factor to their presentation.

Ala97Ser transthyretin amyloidosis-associated polyneuropathy, clinical and neurophysiological profiles in a Thai cohort.

BACKGROUND: Ala97Ser transthyretin amyloidosis-associated polyneuropathy (ATTRA97S-PN) is a rare form of inherited polyneuropathy, usually manifesting with late-onset (> 50) progressive polyneuropathy. This mutation is mostly prevalent in Taiwanese and Han-Chinese individuals. The aim of this study was to describe the clinical and comprehensive neurophysiological profiles of ATTRA97S-PN in Thai patients. METHODS: The clinical profiles and serial neurophysiologic studies (nerve conduction study (NCS), quantitative sensory test (QST), and comprehensive autonomic function test (AFT)) of symptomatic ATTRA97S-PN patients who had been followed-up at King Chulalongkorn Memorial Hospital during 2010-2020 were retrospectively reviewed. RESULTS: Nine symptomatic patients (55.6 % were male) from four unrelated families were included. All were Thais of mixed Thai Chinese descent. The mean age of onset was 48.3 (32-60) years. The mean age at diagnosis was 54.8 (33-66) years. Three patients developed early-onset (< 40y) polyneuropathy. The mean Neuropathy Impairment Score was 41.33 (10-92) at diagnosis. Sensory (9/9) and autonomic (9/9) neuropathies were more frequent than motor neuropathy (5/9), which appeared in the late stage of disease. Hypoesthesia in the feet, and gastrointestinal autonomic symptoms were frequently reported as the initial symptoms. The course of neuropathy progressed over years to decades. The worsening of neuropathy tended to progress faster once motor nerves were affected in both clinical and neurophysiological aspects. Concurrent cardiac amyloidosis was found in 6/9 patients. NCS showed length-dependent sensorimotor axonal polyneuropathy in 5/9 patients, and median neuropathy at the wrist (mostly bilateral) in 7/9 patients. QST showed abnormalities in the vibratory detection threshold, the cold detection threshold and the heat pain sensation in 8/9, 8/9 and 7/7 tested patients, respectively. AFT results were abnormal in all. The mean composite autonomic severity score was 5 (3-9). CONCLUSIONS: This clinical study is the first of ATTRA97S-PN in Thai patients. The mixed polyneuropathy-cardiopathy phenotype was the most common manifestation. In this cohort, the age of onset was lower, and the course of neuropathy was relatively longer, than that in previous studies. Some patients may develop early-onset polyneuropathy. This mutation has not yet been documented in any population other than Han Chinese-related populations, probably suggesting a founder effect. Further studies are warranted.

Neuronavigation based 10 sessions of repetitive transcranial magnetic stimulation therapy in chronic migraine: an exploratory study.

INTRODUCTION: Chronic migraine is a disease of altered cortical excitability. Repetitive transcranial magnetic stimulation provides a novel non-invasive method to target the nociceptive circuits in the cortex. Motor cortex is one such potential target. In this study, we targeted the left motor cortex using fMRI-guided neuronavigation. MATERIALS AND METHODS: Twenty right-handed patients were randomized into real and sham rTMS group. Baseline subjective pain assessments were done using visual analog scale (VAS) and questionnaires: State-Trait Anxiety Inventory, Becks Depression Inventory, and Migraine Disability Assessment (MIDAS) questionnaire. Objectively, pain was assessed by means of thermal pain thresholds using quantitative sensory testing. For corticomotor excitability parameters, resting motor thresholds and motor-evoked potentials were mapped. For rTMS total, 600 pulses in 10 trains at 10 Hz with an intertrain interval of 60 s were delivered in each session. Ten such sessions were given 5 days per week over 2 consecutive weeks. The duration of each session was 10 min. Real rTMS was administered at 70% of Resting MT. All the tests were repeated post-intervention and after 1 month of follow-up. There are no studies reporting the use of fMRI-based TMS for targeting the motor cortex in CM patients. RESULTS: We observed a significant reduction in the mean VAS rating, headache frequency, and MIDAS questionnaire in real rTMS group which was maintained after 1 month of follow-up. CONCLUSION: Ten sessions of fMRI-based rTMS over the left motor cortex may provide long-term pain relief in CM, but further studies are warranted to confirm our preliminary findings.

Thermal Perception Abnormalities Can Predict Diabetic Kidney Disease in Type 2 Diabetes Mellitus Patients.

BACKGROUND: Previous studies have illustrated clinical associations between diabetic peripheral neuropathy (DPN) and diabetic kidney disease (DKD). Quantitative sensory testing (QST) can accurately detect thermal perception abnormalities and aid in the early diagnosis of asymptomatic small-fiber DPN in patients with type 2 diabetes. The aim of this study was to determine the predictive value of thermal perception abnormalities by QST to detect DKD. METHODS: We prospectively enrolled 432 patients with type 2 diabetes (50.2% male, mean age 57.2 years, and average duration of diabetes 9.9 years) at our hospital between 2016 and 2017. Demographic and clinical data of the patients were recorded and analyzed. Diagnosis and staging of DKD were determined by urinary albumin excretion rate and estimated glomerular filtration rate. The presence of thermal perception abnormalities was determined by QST. Multiple logistic regression and receiver operating characteristic (ROC) analyses were performed to investigate the relationships between thermal perception abnormalities and DKD in these patients. RESULTS: In multiple regression analysis, abnormal cold perception in the lower limbs was associated with an increased risk of advanced DKD. Area under the ROC curve analysis revealed that four-limb cold perception abnormalities had the best discriminatory power (0.741 ± 0.053) to predict advanced DKD. CONCLUSIONS: Our results demonstrate the value of using thermal perception abnormalities to identify patients with type 2 diabetes also at risk of DKD.

Short-term test-retest-reliability of conditioned pain modulation using the cold-heat-pain method in healthy subjects and its correlation to parameters of standardized quantitative sensory testing.

BACKGROUND: Conditioned Pain Modulation (CPM) is often used to assess human descending pain inhibition. Nine different studies on the test-retest-reliability of different CPM paradigms have been published, but none of them has investigated the commonly used heat-cold-pain method. The results vary widely and therefore, reliability measures cannot be extrapolated from one CPM paradigm to another. Aim of the present study was to analyse the test-retest-reliability of the common heat-cold-pain method and its correlation to pain thresholds. METHODS: We tested the short-term test-retest-reliability within 40 ± 19.9 h using a cold-water immersion (10 °C, left hand) as conditioning stimulus (CS) and heat pain (43-49 °C, pain intensity 60 ± 5 on the 101-point numeric rating scale, right forearm) as test stimulus (TS) in 25 healthy right-handed subjects (12females, 31.6 ± 14.1 years). The TS was applied 30s before (TSbefore), during (TSduring) and after (TSafter) the 60s CS. The difference between the pain ratings for TSbefore and TSduring represents the early CPM-effect, between TSbefore and TSafter the late CPM-effect. Quantitative sensory testing (QST, DFNS protocol) was performed on both sessions before the CPM assessment. STATISTICS: paired t-tests, Intraclass correlation coefficient (ICC), standard error of measurement (SEM), smallest real difference (SRD), Pearson's correlation, Bland-Altman analysis, significance level p < 0.05 with Bonferroni correction for multiple comparisons, when necessary. RESULTS: Pain ratings during CPM correlated significantly (ICC: 0.411…0.962) between both days, though ratings for TSafter were lower on day 2 (p < 0.005). The early (day 1: 16.7 ± 11.7; day 2: 19.5 ± 11.9; ICC: 0.618, SRD: 20.2) and late (day 1: 1.7 ± 9.2; day 2: 7.6 ± 11.5; ICC: 0.178, SRD: 27.0) CPM effect did not differ significantly between both days. Both early and late CPM-effects did not correlate with the pain thresholds. CONCLUSIONS: The short-term test-retest-reliability of the early CPM-effect using the heat-cold-pain method in healthy subjects achieved satisfying results in terms of the ICC. The SRD of the early CPM effect showed that an individual change of > 20 NRS can be attributed to a real change rather than chance. The late CPM-effect was weaker and not reliable.

Pain perception in healthy young men is modified by time-of-day and is modality dependent.

OBJECTIVE: Several physiological processes exhibit 24-hour oscillations termed circadian rhythms. Despite numerous investigations on the circadian dynamics of pain perception, findings related to this issue remain inconsistent. This study aimed to assess the effect of time-of-day on multimodal experimental pain perception in healthy males, including "static" and "dynamic" quantitative sensory tests. DESIGN: A random order tests were performed in the morning, afternoon and evening. SUBJECTS: Forty-eight healthy males (25.9 ± 4.7 years old). METHODS: Three different pain modalities i) mechanical (pain threshold, tolerance, and intensity), ii) heat (pain threshold and intensity), iii) cold (pain threshold measured in °C and in seconds and cold pain tolerance and intensity) utilizing nine "static" pain parameters, and two "dynamic" pain paradigms i) temporal summation and ii) conditioned pain modulation were assessed in each session. RESULTS: Pain scores varied significantly in six pain parameters during the day. Specifically, lower pain scores were found in the morning for cold pain threshold (in seconds and in °C), cold pain intensity, cold pain tolerance, heat pain threshold and intensity. There were no significant diurnal differences in the mechanical evoked pain parameters or in either of the "dynamic" pain paradigms. CONCLUSIONS: Thermal pain scores varies during the day and morning seems to be the time-of-day most insensitive to pain. Also, dynamic tests and the mechanical pain model are not appropriate for detecting diurnal variability in pain. The results of this study may be partially explained by a potential analgesic effect of some hormones known to have diurnal variation (e.g., melatonin and cortisol).

Effect of a reversal mirror condition on orofacial mechanical sensitivity.

The aim of this study was to investigate whether watching one's own face being touched in a reversal mirror condition modulates orofacial somatosensory sensitivity. A total of 37 healthy volunteers participated in a pilot study, the main study, and a control experiment. In the main experiment, 16 participants received seven different intensities of pinprick stimuli in the right infraorbital region. The perceived stimulus intensity was rated on a 0-50-100 numerical rating scale (NRS). In addition, the pinprick threshold (PiPT) was evaluated in the same region using an electronic von Frey device. During stimuli, participants were watching their own face in two different conditions (normal and reversal mirror) in randomized order. Subjective experiences during each condition were assessed with a questionnaire containing nine statements. The participants rated their level of agreement with the statements using a 7-item Likert scale. There were significant main effects on NRS scores of stimulus forces (p < 0.001) and experimental condition (p < 0.001). Post hoc analyses showed that stimulation with higher force levels induced significantly higher NRS scores (p < 0.001), but interestingly, there were significantly lower NRS scores in the reversal mirror condition than in the normal mirror condition (p < 0.001). There was no significant main effect of experimental condition on PiPT (p = 0.184). The experimental condition influenced the response to several statements significantly (p < 0.001). The somatosensory sensitivity may be impaired when the location of stimulation is not in accordance with the perception. In conclusion, hypoesthetic effects of a reversal mirror were present for fixed force measures but not for threshold measures. Further studies are now needed to describe the potential implications for other somatosensory modalities and orofacial pain conditions.

The Association between Pressure Pain Thresholds, Conditioned Pain Modulation, Clinical Status, and Sleep Quality in Fibromyalgia Patients: A Clinical Trial Secondary Analysis.

Background: Fibromyalgia (FM) is a complex multidimensional disorder primarily characterized by chronic widespread pain, significantly affecting patients' quality of life. FM is associated with some clinical signs found with quantitative sensory testing (QST), sleep disturbance, or psychological problems. This study aims to explore the associations between pressure pain thresholds (PPTs), conditioned pain modulation (CPM), clinical status, and sleep quality in FM patients, offering insights for better clinical management and assessment tools. Methods: This secondary analysis utilized data from a clinical trial involving 129 FM patients. Various assessments, including the Fibromyalgia Impact Questionnaire (FIQ), Pain Catastrophizing Scale (PCS), State-Trait Anxiety Inventory (STAI), and Jenkins Sleep Scale (JSS), were employed to evaluate the clinical and psychological status and sleep quality. PPTs and CPM were measured to understand their relationship with clinical parameters. Results: Our findings revealed that PPTs and CPM are not significantly associated with the clinical status or sleep quality of FM patients. Instead, pain catastrophizing and anxiety state showed a stronger correlation with the impact of fibromyalgia and sleep disturbances. These results highlight the importance of psychological and cognitive factors in managing FM. Conclusions: The study suggests that while PPTs and CPM may not be reliable biomarkers for clinical status in FM, the use of comprehensive assessments including FIQ, PCS, STAI, and JSS can provide a more accurate evaluation of patients' condition. These tools are cost-effective, can be self-administered, and facilitate a holistic approach to FM management, emphasizing the need for personalized treatment plans.

Botulinum Toxin A in the treatment of frostbite sequelae - results from a blinded, early-phase, comparative trial.

INTRODUCTION: Freezing Cold Injuries (FCI) have been associated with long-term sequelae including vasospasm. The aims of the pilot study are to explore the research methodology and investigate the tolerability and safety of treatment with Botulinum Toxin-A (BTX-A) in FCI Sequelae. METHODOLOGY: This pilot study tests the logistics, the treatment setting and the follow-up procedure in an early-phase, double-blinded, randomized, controlled trial study-design. The variables in the study were subjective symptoms, peripheral micro-vascularization/rewarming, somatosensory responsiveness, and generic measure of health status. RESULTS: No major challenges or difficulties were noticed according to the protocol or the study methodology. The monitoring of tolerability and safety of treatment with BTX-A did not reveal any major unwanted and/or adverse reactions among the patients in the pilot study and no challenges occurred during data collection of endpoints. The study revealed an inaccuracy of the 2nd degree FCI diagnosis and uncover a need for relevant and sufficient clinical information for FCI classification. CONCLUSIONS: This pilot study showed the study methodology with minor adjustments is feasible in a future full-scale clinical trial. The recruitment process needs to be more refined to ensure that the eligible study participants are a homogenous group of FCI patients.

Usefulness of thermography in the diagnosis and classification of complex regional pain syndrome.

INTRODUCTION: We propose a protocol for study of complex regional pain syndrome (CRPS) based on a battery of quantitative measures (skin thermography, electrochemical skin conductance and sensory thresholds) and apply such protocol to 5 representative cases of CRPS. PATIENTS AND METHODS: 5 CPRS cases (2 women/3 men) that met the Budapest criteria for the diagnosis of CRPS. RESULTS: All patients showed spontaneous pain and allodynia. Two cases correspond to a stage I, in both the resting basal temperature was increased in the affected limb. Three cases reflect more advanced stages with a decrease in resting temperature and a delay in the recovery of the temperature when compared to contralateral limb. DISCUSSION: These non-invasive quantitative functional tests not only improve the diagnostic accuracy of CRPS but also, they help us to stratify and understand the pathological processes of the disease.

Diagnosis of Central Sensitization and Its Effects on Postoperative Outcomes following Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Central sensitization (CS) has been extensively researched as a cause of persistent pain after total knee arthroplasty (TKA). This systematic review study sought to investigate the diagnosis of CS in patients who underwent TKA for knee osteoarthritis (OA) and the effect of CS on clinical outcomes after TKA. Three comprehensive databases, including MEDLINE, EMBASE, and the Cochrane Library, were searched for studies that evaluated the outcomes of TKA in knee OA patients with CS. Data extraction, risk of bias assessment, and (where appropriate) meta-analysis were performed. The standardized mean difference (SMD) with a 95% confidence interval was used to assess the different scales of pain. A total of eight studies were selected, including two retrospective studies and five prospective observational studies. One study used additional randomized controlled trial data. Five studies were finally included in the meta-analysis. All studies had a minimum follow-up period of 3 months. The Central Sensitization Inventory (CSI), whole-body pain diagram, and quantitative sensory testing (QST) were used for measuring CS. The pooled analysis showed that patients with CS had more severe postoperative pain after TKA (SMD, 0.65; 95% CI, 0.40−0.90; p < 0.01) with moderate heterogeneity (I2 = 60%). In patients who underwent TKA with knee OA, CSI is most often used for the diagnosis of CS, and the QST and whole-body pain diagram are also used. CS is closely associated with more severe and persistent pain after TKA.

Cutaneous allodynia and thermal thresholds in chronic migraine: The effect of onabotulinumtoxinA.

OBJECTIVE: Cutaneous allodynia (CA) is a common symptom in migraine. Its incidence is more frequent in the chronic migraine (CM). CA usually occurs during pain attacks. However, it can also be interictal and its frequency and severity seem to be correlated with the duration of the disease. Several quantitative sensory testing (QST) studies have revealed variable results about mechanical and thermal allodynia accompanying migraine. This study aimed to investigate the effects of CA and onabotulinumtoxinA (BoNT-A) injection on the thermal thresholds measured by QST in patients with CM. The effects of BoNT-A on headaches, CA, and other accompanying symptoms of migraine were also evaluated. METHODS: Single BoNT-A injections were performed in 22 female cases (mean age: 38.1 ± 7.2 years) with CM. Patients were evaluated at 1-7 days before, 28-35, and 84-91 days after the injection. The 22 healthy women in the control group (mean age: 36.6 ± 7.6 years) were examined once. Headache and its characteristics, medication intake, allodynia, presence of anxiety, and depression symptoms were evaluated through relevant scales. The heat (HDT) and cold (CDT) detection thresholds on the forehead and hand were measured bilaterally with QST. The presence of brush allodynia for patients was examined by applying a 4 × 4 gauze pad over the same areas. RESULTS: The patients in the CM group had migraine for an average of 22.5 ± 6.1 years and CM for 6.1 ± 3.2 years. The average number of painful days per month was 22.1 ± 4.0 days. All the patients had migraine attacks with CA (mean 5.6/month). The average allodynia symptom checklist (ASC-12) score was 7.8 ± 6.2. Thermal thresholds measured in the patients with CM were similar to those of the controls. Thermal thresholds did not show significant differences between the symptomatic and the asymptomatic sides at the last migraine attack. There was also no correlation between the allodynia revealed by the physical examination and the thermal thresholds detected by QST. The ASC-12 score decreased significantly with BoNT-A injection (p = 0.030), but no significant change was observed in thermal thresholds after this treatment. CONCLUSION: There was no significant correlation between CA and thermal thresholds. BoNT-A was successful in relieving headache and other associated symptoms, including CA, but had no significant effect on QST parameters.

The effect of high-definition transcranial direct current stimulation on pain processing in a healthy population: A single-blinded crossover controlled study.

Transcranial direct current stimulation (tDCS) is increasingly used in pain treatment. tDCS targeting both primary motor cortex (M1) and dorsolateral prefrontal cortex (DLPFC) may modulate the descending pain inhibitory system, however, it remains controversial regarding the optimal stimulation region for pain modulation. Therefore, this study aimed to explore the effects of high-definition anodic stimulation of M1 and DLPFC on conditioned pain modulation (CPM) and pain thresholds and establish a preferred stimulation setting. Twenty-six healthy adults were randomly assigned to M1-tDCS, DLPFC-tDCS, or sham-tDCS groups. During the three sessions, each participant received an active or sham stimulation of 2 mA for 20 min, with at least 3 days' interval between sessions. Quantitative sensory tests were performed to obtain pressure pain threshold (PPT), cold pain threshold (CPT), and CPM before and after the tDCS intervention. Only M1-tDCS significantly increased CPM in healthy individuals compared with sham control (P = 0.004). No statistically significant difference was found in PPT and CPT between tDCS vs. sham control (P > 0.05). Our findings further support the important role of M1 as a target in pain regulation. Further large-scale, multicenter studies in chronic pain populations are needed to validate the alterations of distinct target brain regions related to pain and thus for an optimal target stimulation strategy in pain management.

Sensory alteration patterns in burned patients.

INTRODUCTION: Burned patients may present with different type and severity of sensory dysfunction. Regenerative mechanisms in the peripheral nervous system are diminished after burn injury and thus unable to accurately regenerate somatosensitive skin receptors. The pattern by which neuronal regeneration occurs to regain this sensitivity in burn patients is still unclear. PATIENTS AND METHOD: This observational retrospective study focuses on determining the patterns of heat, heat-pain, cold, cold-pain, sympathetic skin response and touch following severe burns. Twenty-six burn patients with different type of burns were included in the study. The survey methods used included the Quantitative Sensory Test for termoalgesic measurement, electrical SSR and the Von Frey filaments for quantitative measurements of touch/pressure. RESULTS: The results showed that patients present with hypoesthesia to heat, cold, and touch in postburn skin areas compared with the contralateral healthy areas. However, in the heat-pain sensation, no hypoesthesia was noted. CONCLUSIONS: Our results suggest that burn patients have a sensitivity dysfunction in postburned skin areas. The use of QST could be considered the technique to determine the sensitivity of burned patients. Although, more high-quality studies should to be done.

The effects of silicone-based resilient denture liners on pain: A randomized controlled trial.

PURPOSE: This randomized controlled trial aimed to study the effects of lining mandibular complete dentures with silicone-based resilient denture liners, especially with respect to sensation. METHODS: The trial included completely edentulous patients who were willing to fabricate new set of complete denture. A random permuted block method (block size: 4) was used to assign participants to one of the following groups: mandibular conventional denture (CD) group or mandibular denture with resilient denture liner (RD) group. The outcomes were evaluated using both, objective measures (current perception threshold (CPT) and pain threshold (PT)) for external stimuli measured using the Neurometer CPT® and subjective measures (physical pain and psychological discomfort measured using the Japanese version of Oral Health Impact Profile for Edentulous patients-OHIP-EDENT-J). The outcomes were measured twice, at immediately after completion of denture adjustments (first measurement), and 3 months after the completion of denture adjustments (second measurement). All outcomes were analyzed using the Student t-test. A p-value of <0.05 was considered statistically significant. RESULTS: CPT was significantly higher with RD than CD only at second measurement with frequency level of 2000 Hz and 5 Hz. The pain thresholds were significantly higher in the RD group than the CD group. The physical pain and psychological discomfort scores were significantly lower in the RD group than in the CD group. CONCLUSION: This study concludes that edentulous patients wearing mandibular complete dentures with silicone-based resilient denture liners dull perception mandibular ridge mucosa and felt less pain than those without the liners.

Usefulness of thermography in the diagnosis and classification of complex regional pain syndrome.

INTRODUCTION: We propose a protocol for study of complex regional pain syndrome (CRPS) based on a battery of quantitative measures (skin thermography, electrochemical skin conductance and sensory thresholds) and apply such protocol to 5 representative cases of CRPS. PATIENTS AND METHODS: 5 CPRS cases (2 women/3 men) that met the Budapest criteria for the diagnosis of CRPS. RESULTS: All patients showed spontaneous pain and allodynia. Two cases correspond to a stage I, in both the resting basal temperature was increased in the affected limb. Three cases reflect more advanced stages with a decrease in resting temperature and a delay in the recovery of the temperature when compared to contralateral limb. DISCUSSION: These non-invasive quantitative functional tests not only improve the diagnostic accuracy of CRPS but also, they help us to stratify and understand the pathological processes of the disease.