Quantitative sensory testing: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

Is the Central Sensitization Inventory (CSI) associated with quantitative sensory testing (QST)? A systematic review and meta-analysis

Central sensitization (CS) involves an amplification of neural processing within the central nervous system that can result in widespread pain patterns and hypersensitivity to stimuli. The Central Sensitization Inventory (CSI) and various quantitative sensory testing (QST) methods purport to assess clinical markers of CS. The purpose of this systematic review and meta-analysis was to summarize and quantify the associations between total CSI scores and QST measures from previous studies. A systematic search identified 39 unique studies that were deemed eligible for the systematic review and 33 studies for meta-analyses (with 3314 subjects and 154 effect sizes), including five QST modalities: conditioned pain modulation, temporal summation, pressure pain threshold, heat pain threshold, and cold pain threshold. The meta-analysis yielded statistically significant CSI-QST correlations in total subject samples for all five QST modalities. The strongest associations were identified between CSI scores and pain threshold testing, especially pressure pain threshold, in which 51% of effects sizes, from 29 studies and 3071 subjects, were determined to be in a medium to large range.

The Impact of Music Perception on Quantitative Sensory Testing (QST)

Objective: The impact of listening to music on pain perception has been evaluated using questionnaires and numeric/visual analogue scales. In this study, the impact of music perception on sensory pain functions was measured by means of quantitative sensory testing. Methods: We enrolled 10 female and 10 male healthy subjects (10 of them were professional musicians). All subjects underwent, in total, four quantitative sensory testing measures (first: baseline; second: after pleasant music [Johannes Brahms, 3rd symphony, 3rd movement]; third: after unpleasant music [Krzysztof Penderecki, Threnos]; fourth: after a longer break). The pleasantness of music was evaluated using the Ertel differential scale. Results: After the participants listened to pleasant music, an increased sensitivity to cold stimuli (both threshold and pain), to mechanical stimuli (only for threshold), and to repeated stimuli (wind-up reaction) was noted. Listening to unpleasant music was not associated with changes in sensitivity. We did not observe any significant differences between male and female subjects or between musicians and non-musicians. There was no significant correlation between the rating of the music as pleasant/unpleasant and the different quantitative sensory testing measures. Conclusions: Our data show that listening to music inducing a pleasant feeling can increase the sensitivity to stimuli applied during a quantitative sensory testing session. This should be considered when performing or interpreting quantitative sensory testing examinations. Interestingly, this finding is in contrast to the observation that listening to music can decrease pain perception during painful procedures.

The thermal sensation threshold and its reliability induced by the exposure to 28 GHz millimeter-wave

The application of 28 GHz millimeter-wave is prevalent owing to the global spread of fifth-generation wireless communication systems. Its thermal effect is a dominant factor which potentially causes pain and tissue damage to the body parts exposed to the millimeter waves. However, the threshold of this thermal sensation, that is, the degree of change in skin temperature from the baseline at which the first subjective response to the thermal effects of the millimeter waves occurs, remains unclear. Here, we investigated the thermal sensation threshold and assessed its reliability when exposed to millimeter waves. Twenty healthy adults were exposed to 28 GHz millimeter-wave on their left middle fingertip at five levels of antenna input power: 0.2, 1.1, 1.6, 2.1, and 3.4 W (incident power density: 27-399 mW/cm2). This measurement session was repeated twice on the same day to evaluate the threshold reliability. The intraclass correlation coefficient (ICC) and Bland-Altman analysis were used as proxies for the relative and absolute reliability, respectively. The number of participants who perceived a sensation during the two sessions at each exposure level was also counted as the perception rate. Mean thermal sensation thresholds were within 0.9°C-1.0°C for the 126-399 mW/cm2 conditions, while that was 0.2°C for the 27 mW/cm2 condition. The ICCs for the threshold at 27 and 126 mW/cm2 were interpreted as poor and fair, respectively, while those at higher exposure levels were moderate to substantial. Apart from a proportional bias in the 191 mW/cm2 condition, there was no fixed bias. All participants perceived a thermal sensation at 399 mW/cm2 in both sessions, and the perception rate gradually decreased with lower exposure levels. Importantly, two-thirds of the participants answered that they felt a thermal sensation in both or one of the sessions at 27 mW/cm2, despite the low-temperature increase. These results suggest that the thermal sensation threshold is around 1.0°C, consistent across exposure levels, while its reliability increases with higher exposure levels. Furthermore, the perception of thermal sensation may be inherently ambiguous owing to the nature of human perception.

Dorsal Root Ganglion Stimulation in Chronic Painful Polyneuropathy: A Potential Modulator for Small Nerve Fiber Regeneration

OBJECTIVES

Neuromodulatory treatments like spinal cord stimulation and dorsal root ganglion stimulation (DRGS) have emerged as effective treatments to relieve pain in painful polyneuropathy. Animal studies have demonstrated that neurostimulation can enhance nerve regeneration. This study aimed to investigate if DRGS may impact intraepidermal nerve fiber regeneration and sensory nerve function.

MATERIALS AND METHODS

Nine patients with chronic, intractable painful polyneuropathy were recruited. Intraepidermal nerve fiber density (IENFD) quantification in 3 mm punch skin biopsy was performed 1 month before DRGS (placed at the level of the L5 and S1 dorsal root ganglion) and after 12- and 24-month follow-up. Quantitative sensory testing, nerve conduction studies, and a clinical scale score were also performed at the same time points.

RESULTS

In 7 of 9 patients, DRGS was successful (defined as a reduction of ≥ 50% in daytime and/or night-time pain intensity), allowing a definitive implantable pulse generator implantation. The median baseline IENFD among these 7 patients was 1.6 fibers/mm (first and third quartile: 1.2; 4.3) and increased to 2.6 fibers/mm (2.5; 2.9) and 1.9 fibers/mm (1.6; 2.4) at 1- and 2-years follow-up, respectively. These changes were not statistically significant (p = 1.000 and 0.375). Sensory nerve tests did not show substantial changes.

CONCLUSIONS

Although not significant, the results of this study showed that in most of the patients with implants, there was a slight increase of the IENFD at the 1- and 2-year follow-up. Larger-scale clinical trials are warranted to explore the possible role of DRGS in reversing the progressive neurodegeneration over time.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT02435004; Swiss National Clinical Trials Portal: SNCTP000001376.

Pain assessment in autism: updating the ethical and methodological challenges through a state-of-the-art review

Sensory features of autism include hypo- or hyper-reactivity to pain; however, previous studies on pain in autism lead to conflicting results. Here, we present the state of the art and the methodological challenges concerning pain perception in autism, focusing on studies that used standardized protocol as Quantitative Sensory Testing (QST) to measure perception. Despite there are still scant evidences found with the use of QST, they have challenged the presumed hyposensitivity to pain in autisms, which emerged from parents' reports. Both, peripheral and central mechanisms, have been found involved in typical features of perception in autism. Nonetheless, evidences with controlled protocols are still scarce, and even scarcer are studies focused on children. Overall, complex ethical challenges have to be overcome in order to collect subjective and objective measures from autistic children. With heterogeneous neurodevelopmental features, or intellectual disability, novel or modified protocols are needed.

Percutaneous glycerol rhizolysis of the trigeminal ganglion for the treatment of idiopathic and classic trigeminal neuralgia: Outcomes and complications

BACKGROUND AND PURPOSE

Patients with idiopathic trigeminal neuralgia (TN) with absent arterial contact or venous contact only and classic TN with morphological changes of the trigeminal nerve secondary to venous compression are not routinely recommended microvascular decompression at our institution. In patients with these anatomical subtypes of TN, limited data exists describing the outcomes of percutaneous glycerol rhizolysis (PGR) of the trigeminal ganglion (TG).

METHODS

We performed a retrospective single-center cohort study and analyzed outcomes and complications after PGR of the TG. Clinical outcome after PGR of the TG was assessed via the Barrow Neurological Institute (BNI) Pain Scale.

RESULTS

Forty-five patients underwent a total of 66 PGRs of the TG. At short-term follow-up, 58 procedures (87.9%) resulted in a BNI score of I (i.e., freedom from pain without medication). At a median follow-up of 3.07 years, 18 procedures (27.3%) resulted in a BNI score of I, 12 procedures (18.1%) resulted in BNI score of IIIa, and 36 procedures (54.5%) resulted in a BNI score of IIIb-V. The median length of freedom from pain without medication was 1.5 years. Eighteen procedures (27.3%) caused hypesthesia and two (3.0%) caused paresthesias. There were no serious complications.

CONCLUSION

In patients with these anatomical subtypes of TN there was a high rate of short-term pain relief for the first 1-2 years and thereafter a large proportion of patients experienced pain relapse. In this patient group, PGR of the TG represents a safe procedure that is efficacious in the short term.

Autonomic nervous system disorders in multiple sclerosis

Multiple sclerosis (MS) is a chronic progressive demyelinating disease of the central nervous system (CNS), which also affects the autonomic nervous system (ANS). Manifestations of MS in the ANS include urological, sexual, gastrointestinal, cardiovascular, and thermoregulatory disorders as well as increased fatigue. These problems are common yet are often underestimated due to the non-specificity of the symptoms and the limited evaluation of the ANS in the usual clinical practice. Most of these symptoms seem to be related to localized lesions in the CNS. However, the mechanisms by which these disorders are caused in MS have not been fully investigated, thus preventing any focused etiological treatment. The most common disorders of the ANS in MS represent a challenge for clinicians due to the variability of the clinical picture and our minimal data on their diagnosis and treatment. Early diagnosis and initiation of individualized treatment regimens, often in need of multiple approaches, seem to yield the best results in managing ANS dysfunction in MS patients.

Visual-somatosensory integration (VSI) as a novel marker of Alzheimer’s disease: A comprehensive overview of the VSI study

Identification of novel, non-invasive, non-cognitive based markers of Alzheimer’s disease (AD) and related dementias are a global priority. Growing evidence suggests that Alzheimer’s pathology manifests in sensory association areas well before appearing in neural regions involved in higher-order cognitive functions, such as memory. Previous investigations have not comprehensively examined the interplay of sensory, cognitive, and motor dysfunction with relation to AD progression. The ability to successfully integrate multisensory information across multiple sensory modalities is a vital aspect of everyday functioning and mobility. Our research suggests that multisensory integration, specifically visual-somatosensory integration (VSI), could be used as a novel marker for preclinical AD given previously reported associations with important motor (balance, gait, and falls) and cognitive (attention) outcomes in aging. While the adverse effect of dementia and cognitive impairment on the relationship between multisensory functioning and motor outcomes has been highlighted, the underlying functional and neuroanatomical networks are still unknown. In what follows we detail the protocol for our study, named The VSI Study, which is strategically designed to determine whether preclinical AD is associated with neural disruptions in subcortical and cortical areas that concurrently modulate multisensory, cognitive, and motor functions resulting in mobility decline. In this longitudinal observational study, a total of 208 community-dwelling older adults with and without preclinical AD will be recruited and monitored yearly. Our experimental design affords assessment of multisensory integration as a new behavioral marker for preclinical AD; identification of functional neural networks involved in the intersection of sensory, motor, and cognitive functioning; and determination of the impact of early AD on future mobility declines, including incident falls. Results of The VSI Study will guide future development of innovative multisensory-based interventions aimed at preventing disability and optimizing independence in pathological aging.

Quantitative thermal testing as a screening and follow-up tool for diabetic sensorimotor polyneuropathy in patients with type 2 diabetes and prediabetes

Introduction

The diagnosis and assessment of neuropathy severity of diabetic sensorimotor polyneuropathy (DSPN) are mainly based on clinical neuropathy scores and electrophysiologic studies. This study aimed to determine whether quantitative thermal testing (QTT) can be used as a screening and follow-up tool for DSPN of prediabetes and type 2 diabetes at baseline and at 1-year follow-up.

Methods

All patients were assessed using the Toronto Clinical Neuropathy Score (TCNS) and underwent electrophysiological testing, including a nerve conduction study (NCS) and QTT, at baseline and at a 1-year follow-up. The TCNS and the composite scores of nerve conduction were used to assess the severity of DSPN. The DSPN status at the 1-year follow-up was classified as remaining no DSPN, remaining DSPN, regression to no DSPN, or progression to DSPN.

Results

Diabetic sensorimotor polyneuropathy was initially diagnosed in 89 patients with prediabetes and type 2 diabetes (22%). The regressed to no DSPN in 29 patients and progressed to DSPN in 20 patients at the 1-year follow-up. TCNS was significantly correlated with composite scores of nerve conduction, hand cold detection threshold (CDT), hand warm detection threshold (WDT), foot CDT, and foot WDT. Stepwise logistic regression demonstrated that the foot CDT (p < 0.0001) was independently associated with the presence of DSPN. The TCNS, composite scores of the nerve conduction, hand WDT, hand CDT, foot WDT, and foot CDT were all statistically significant among the four different DSPN status groups at two different time periods (baseline and the 1-year follow-up).

Conclusion

The foot CDT can be used as an initial screening tool for DSPN alternatively. The characteristics of nerve damage after 1 year of DSPN can be progressive or reversible, and the neurological functions of large and small fibers have a parallel trend, which can be objectively measured by NCS and QTT.

Convergent Validity of the Central Sensitization Inventory in Women with Fibromyalgia: Association with Clinical, Psychological and Psychophysical Outcomes

BACKGROUND

To assess the relationship between demographic, clinical, psychological, and pressure pain sensitivity outcomes with the central sensitization inventory (CSI) in female with fibromyalgia (FMS).

METHODS

One hundred twenty-six (n=126) females with FMS completed demographic (age, body mass index, height, weight), clinical (pain history, pain intensity at rest and during daily living activities), psychological (depression/anxiety levels) outcomes and widespread pressure pain sensitivity as well as the central sensitization inventory (CSI). After conducting a multivariable correlation analysis to identify the association between variables, a multiple linear regression model was performed to identify CSI predictors.

RESULTS

The CSI was negatively associated with age (r=-0.262) and PPTs (r ranged from -0.221 to -0.372) and positively associated with anxiety (r=0.541), depression (r=0.415), mean intensity (r=0.305), worst pain (r=0.249), and pain during daily living activities (r= 0.398). The stepwise regression analysis revealed that 47.4% of CSI variance in this sample was explained by anxiety levels (27.8%), PPT at greater trochanter (10.5%), age (1.4%), years with pain (4.8%) and pain during daily living activities (2.9%).

CONCLUSION

The current study found that age, pain intensity at rest and pain during daily living activities, anxiety levels, and pressure pain sensitivity are associated with the CSI (associated sensitization symptoms) in women with FMS.

Feasibility of quantitative sensory testing in juvenile idiopathic arthritis

OBJECTIVE

Juvenile Idiopathic Arthritis (JIA) is a childhood-rheumatic disease with pain as a major early complaint, and in 10-17% pain remains a major symptom. Very few data exist on sensory threshold changes at the knee in JIA, a location in which inflammation often manifests. We determined whether JIA is associated with sensory threshold changes at the knee by using Quantitative Sensory Testing (QST) and established reference values at the knee of children.

METHODS

Sixteen patients with JIA aged 9-18 years with one affected knee and a patient-reported pain by Visual Analog Scale (VAS) > 10 on a 0-100 scale, and 16 healthy controls completed the study and were included for the analysis. QST was assessed in compliance with the German Research Network on Neuropathic Pain (DFNS) standard. Disease severity was determined using Juvenile Disease Activity Score (JADAS. Perceived pain was assessed with a visual analogue scale(0-100). Feasibility of QST was tested in patients aged 6-9.

RESULTS

Under the age of 9, QST testing showed not to be feasible in 3 out of 5 JIA patients. Patients with JIA aged 9 and older reported an average VAS pain score of 54.3. QST identified a significant reduction in pressure pain threshold (PPT) and increase in cold detection threshold (CDT) compared to healthy controls. PPT is reduced in both the affected and the unaffected knee, CDT is reduced in the unaffected knee, not the affected knee.

CONCLUSION

In a Dutch cohort of Patients with JIA, QST is only feasible from 9 years and up. Also, sensory threshold changes at the knee are restricted to pressure pain and cold detection thresholds in Patients with JIA.

PERSPECTIVE

This article shows that in a Dutch population, the extensive QST protocol is only feasible in the age group from 9 years and older, and a reduced set of QST tests containing at least pressure pain thresholds and cold detection thresholds could prove to be better suited to the pediatric setting with arthritis.

The Relevance of Collision Tests and Quantitative Sensory Testing in Diagnostics and Postoperative Outcome Prediction in Carpal Tunnel Syndrome

Background

The gold standards for the diagnosis and treatment of carpal tunnel syndrome (CTS) and its outcome are undecided. Using clinical and electrophysiological methods, we tried to establish which fibers achieved full postoperative recovery, and the possibility of using non-standard electrophysiological tests as outcome predictors.

Methods

The study group consisted of 35 patients and controls. The Historical–Objective Scale, standard neurography, conduction velocity distribution tests (CVD), and quantitative sensory testing (QST) were performed before and after CTS surgery.

Results

Clinical improvement was observed on average in 54.3% of the patients, higher in less advanced CTS. All parameters improved significantly after surgery, except for CVD; most remained worse than in the controls. Only QST parameters fully returned to normal limits. Patient age and CTS severity were important in the estimation of the risk of no improvement.

Conclusions

The efficiency of minimally invasive CTS surgery is higher in younger patients with less advanced CTS. Complete recovery was present only in small fibers; larger fibers could most likely be responsible for residual signs. We did not notice any benefits in CTS diagnosis using methods of small fiber assessment. QST seemed to be useful in the diagnosis of residual signs, and in deciding upon possible reoperation.

Mechanistic approach towards diabetic neuropathy screening techniques and future challenges: A review

Diabetic neuropathy, also called peripheral diabetic neuropathy (PDN), is among the most significant diabetes health consequences, alongside diabetic nephropathy, diabetic cardiomyopathy and diabetic retinopathy. Diabetic neuropathy is the existence of signs and indications of peripheral nerve damage in patients with diabetes after other causes have been governed out. Diabetic neuropathy is a painful and severe complication of diabetes that affects roughly 20% of people. The development of diabetic neuropathy is regulated by blood arteries that nourish the peripheral nerves and metabolic problems such as increased stimulation of polyol pathway, loss of myo-inositol and enhanced non-enzymatic glycation. It's divided into four types based on where neurons are most affected: autonomic, peripheral, proximal, and focal, with each kind presenting different symptoms like numbing, gastrointestinal disorders, and heart concerns. Pharmacotherapy for neuropathic pain is complex and for many patients, effective treatment is lacking; as a result, scientific proof recommendations are crucial. As a result, the current demand is to give the most vital medications or combinations of drugs that work directly on the nerves to help diabetic neuropathy patients feel less pain without causing any adverse effects. In diabetic neuropathy research, animal models are ubiquitous, with rats and mice being the most typically chosen for various reasons. This review covers the epidemiology, clinical features, pathology, clinical symptom, mechanism of diabetic neuropathy development, diagnosis, screening models of animals, diabetic neuropathy pharmacotherapy.

NEURO TOUCH: A novel digital device for assessment and screening of peripheral neuropathy

BACKGROUND

Most of the patients suffering from diabetes develop Sensory neuropathy which proceeds with development of painful neuropathy. This can lead to formation of ulcers in later stages. Currently, available Quantitative Sensory Testing (QST) devices take more time to perform and are expensive. NEURO TOUCH is such device which combines four parameters of QST in one unit. Its portable, battery operated and handy device with real time display of results along with data storage and data transfer facility. It can perform tactile sensation threshold, vibration and thermal testing threshold along with skin temperature measurement. This study was undertaken to establish the diagnostic validity, reproducibility and repeatability for early detection of peripheral neuropathy.

METHODS

A total of 317 subjects were recruited for QST assessment with NEURO TOUCH; Tactile threshold sensation, vibration perception and thermal threshold testing along with skin temperature. A subset of 30 subjects in each group were considered for repeatability and reproducibility test.

RESULTS

The mean difference for vibration perception threshold was 0.6 when compared with gold standard device. Regarding the cold and warm perception threshold the mean difference was 1.1 and 2 °C respectively when compared with gold standard device. For skin temperature measures there was a mean difference of 1.2 °C with respect to standard device.

CONCLUSIONS

The NEURO TOUCH device was easy-to-use, compact and provided an efficient multimodality approach which can help for screening of peripheral neuropathy patients with type 2 diabetes.

The applicability of the digit wrinkle scan to quantify sympathetic nerve function

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Normative values for stimulated skin wrinkling are age-dependent.

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Stimulated skin wrinkling has never been evaluated quantitatively.

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The clinical application of the stimulated skin wrinkling in an ordinal fashion is doubtful.

Objective

Stimulated skin wrinkling test (SSW) has been launched as a non-invasive diagnostic procedure. However, no normative age dependent values have been reported that can be applied in clinical practice. The objectives of the study were to (1) collect age-dependent normative values according to the 5-point scale assessment for the SSW, to (2) determine reliability scores for the obtained norm values, and to (3) introduce a new digital method for SSW assessment, the Digit Wrinkle Scan© (DWS©) for detection of wrinkles in a more quantitative manner.

Methods

Firstly, 82 healthy participants were included, divided in 5 age groups. The participants underwent SSW using lidocaine and prilocaine topical cream. Secondly, 35 healthy participants were included to test whether the DWS© could be a novel manner to assess the grade of wrinkling quantitatively. We determined the inter-observer reliability of both methods. Also, the intra-observer reliability was calculated for the DWS©.

Results

We found a decrease in normative values over age. The inter-observer reliability of assessment by the 5-point scale method was moderate after SSW (Cohen’s k: 0.53). Results of the DWS© indicate that total wrinkle length per mm² showed moderate to good agreement for the 4th and 5th digits after SSW, and a low agreement for the other digits.

Conclusions

Age-dependent normative values were obtained according to the 5-point scale, but its clinical application is doubtful since we found a moderate inter-observer reliability. We introduced the DWS© as a possible new method in order to quantify the grade of wrinkling.

Significance

We found unsatisfactory reliability scores, which hampers its usefulness for clinical practice.

Diabetes Distal Peripheral Neuropathy: Subtypes and Diagnostic and Screening Technologies

Diabetes distal symmetrical peripheral neuropathy (DSPN) is the most prevalent form of neuropathy in industrialized countries, substantially increasing risk for morbidity and pre-mature mortality. DSPN may manifest with small-fiber disease, large-fiber disease, or a combination of both. This review summarizes: (1) DSPN subtypes (small- and large-fiber disease) with attention to clinical signs and patient symptoms; and (2) technological diagnosis and screening for large- and small-fiber disease with inclusion of a comprehensive literature review of published studies from 2015-present (N = 66). Review findings, informed by the most up-to-date research, advance critical understanding of DSPN large- and small-fiber screening technologies, including those designed for point-of-care use in primary care and endocrinology practices.

Current Challenges in the Management of Chronic Pelvic Pain in Women: From Bench to Bedside

Chronic pelvic pain (CPP) affects a significant proportion of women worldwide And has a negative impact on several aspects of these women’s lives including mental health, work, relationships and sexual function, among others. This set of factors ultimately reflects negatively on quality Of life. The physiopathology of CPP is complex and remains to be fully clarified; however, recent advances have increased understanding of the mechanisms involved in chronic pain in general, and more specifically, CPP. Nonetheless, even when a detailed clinical history is obtained, meticulous physical examination is performed and imaging resources are appropriately used, the organic cause of the pain may still fail to be identified in a substantial number of women with CPP. Management of CPP may therefore be challenging. This narrative review was aimed at adding to the available literature on the subject, presenting and discussing the principal characteristics of CPP in women. The paper highlights gaps in the literature while providing the most up-to-date evidence associated with the physiopathology and classification of pain, its diagnosis and treatment. In addition, current challenges in the management of women with CPP are discussed.

The Effects of Diabetic Polyneuropathy and Autonomic Neuropathy on Bone Turnover

Background: The effect of diabetic polyneuropathy (DPN) and autonomic neuropathy (AN) on bone turnover in type 2 diabetes mellitus (DM) is uncertain due to the lack of data. In this study, we tried to determine the effect of DPN and AN on bone metabolism. Materials and Methods: The study included patients with type 2 DM (aged 18-80 years) and age-matched healthy individuals who presented to the Departments of Metabolism and Diabetes, Geriatrics, and General Internal Medicine, Cerrahpaşa Medical School, Istanbul University. The patients were examined to find out whether they had AN, and neuropathy scores were recorded by exploring peripheral neuropathy. Bone mineral density was measured by dual-energy X-ray (DXA). Demographic characteristics, the presence of microvascular complications, and biochemical data were obtained from patients' files. Serum cross-linked C-telopeptide (Ctx), osteocalcin, and bone-specific alkaline phosphatase (B-ALP) were analyzed. Results: The study comprised a total of 64 patients: 23 had type 2 DM and osteoporosis (OP) (duration of diabetes 10.1 ± 7 years; mean age 63 ± 9.1 years; female/male 18/5; Group 1), 41 had type 2 DM and non-OP (duration of diabetes 10.3 ± 7.6 years; mean age 58 ± 7.4 years; female/male 30/11; Group 2), and 26 healthy volunteers made up the control group (mean age 62 ± 11.9 years; female/male 14/12; Group 3). The bone turnover parameters were lower in type 2 DM individuals. The levels of osteocalcin (13.3 ± 5.2 ng/mL) and B-ALP (44.7 ± 10.9 IU/L) in patients with type 2 DM were lower than those of healthy subjects: osteocalcin (20.6 ± 10 ng/mL) and B-ALP (111 ± 31.4 IU/L; P = 0.001 and P = 0.000, respectively). Ctx levels (193.5 ± 49.3; 207.6 ± 40 ng/mL) were recorded to be similar (P = 0.2). AN was also noted as a risk factor for OP. For patients without AN, the likelihood of developing OP (odds ratio) was 0.7. The corresponding ratio for patients with AN was 9.3. Conclusions: Among the independent variables, the neuropathy score was determined to have an impact on bone turnover. AN was identified to be a significant risk factor for OP.

[Quantitative sensory testing for neuropathic pain and its relevance for physiotherapy]

BACKGROUND

Neuropathic pain syndromes are typically characterized by high chronification rates as well as long and intensive pain episodes. Early and accurate diagnosis of neuropathic pain is a basic skill of physiotherapists and other medical professionals, may allow for appropriate medical treatment and help to prevent possible consequential damage. Quantitative sensory testing (QST) can be applied as a supplement to conventional neurological bedside testing in the evaluation of neuropathic pain. Over recent decades, QST has come to hold a significant position in the field of pain research. However, despite these developments, the application of QST in clinical practice has lagged behind.

OBJECTIVES

What is the value of QST in the study of neuropathic pain? Have the conditions for personal clinical use of the QST been established in physiotherapy practice? Have the pathways for specific implementation of the QST been defined?

METHOD

Literature research as part of a Bachelor thesis in Physiotherapy.

RESULTS

QST constitutes a valid examination tool that is able to evaluate the complete somatosensory profile. In this way, QST may provide substantial additional benefit in the examination of neuropathic pain patients compared to other conventional testing procedures, especially when it comes to small-fibre neuropathies. These small fibres seem to be particularly affected in asymptomatic patients as well as early phases of neuropathies and cannot be investigated via conventional testing procedures. This makes the use of partial aspects of the QST a proven instrument for physiotherapists and medical staff, which was particularly useful in the decision-making process for neuropathies.

DISCUSSION

Nonetheless, regarding the results, there are still several limiting factors that hamper the routine use of QST. Some of these can be resolved by precisely adhering to testing protocols and taking precautions. Other highly relevant issues for clinical practice, such as the immense cost of equipment and the excessive time required for testing, have not been satisfactorily overcome as yet. Less comprehensive testing protocols as well as the innovation of handy and cost-effective testing devices might offer initial approaches to enhance the widespread use of QST. Complementing conventional bedside testing by adding thermal discrimination tests and pain detection threshold tests might prove to be another possibility to integrate the benefit of QST into clinical practice.

CONCLUSION

QST makes a significant contribution to the investigation and diagnosis of neuropathies. Physiotherapists are encouraged to implement partial aspects of the QST in a standard examination in order to have a positive effect on both early detection and treatment.

Pelvic floor, abdominal and uterine tenderness in relation to pressure pain sensitivity among women with endometriosis and chronic pelvic pain

OBJECTIVE

Pelvic floor pain, abdominal wall pain, and central nervous system pain amplification can be contributing factors in chronic pelvic pain (CPP), however; limited research has investigated the association of pelvic floor, abdominal, and uterine tenderness with central nervous system pain amplification. We assessed whether pressure pain thresholds on the non-dominant thumbnail, a marker of central nervous system pain amplification, were associated with pelvic floor, abdominal, and uterine tenderness among women with endometriosis or CPP.

STUDY DESIGN

We conducted a cross-sectional study among 88 females with endometriosis and/or CPP. Abdominal (6 locations), pelvic floor (6 locations) and uterine (1 location) tenderness were assessed via a standardized physical exam. Participants reported their pain levels (0-10 scale) with application of 2 kg of pressure at each area, with a pain rating of ≥4 on the 0-10 scale considered moderate to severe pain. Pain sensitivity was measured on the non-dominant thumbnail by applying discrete pressure stimuli using a previously validated protocol.

RESULTS

Overall, 50% (44/88), 42% (37/88), and 58% (51/88) of participants reported high pelvic floor, abdominal, and uterine tenderness, respectively. Pressure intensities needed to elicit 'faint' and 'mild' pain were lower for participants with high vs. low pelvic floor tenderness (median intensity for 'faint' pain = 0.50 kgf/cm²(min-max:0.25-3.25) vs. 1.06(0.25-3.00), p-value = 0.006; median intensity for 'mild' pain = 2.00(0.63-4.88) vs. 2.63(0.75-6.00), p-value = 0.03). No association was observed between pressure pain sensitivity and abdominal or uterine tenderness (p > 0.11). Participants with endometriosis without pain were less likely to have high pelvic floor (22.2%), abdominal (11.1%), and uterine (25.9%) tenderness compared to participants with endometriosis with pain (63.0%, 50%, 65.2%, respectively) and participants with chronic pelvic pain (60%, 73.3%, 93.3%, respectively).

CONCLUSIONS

These results suggest that high pelvic floor tenderness among women with endometriosis/CPP may be a marker of heightened pain sensitivity suggestive of central nervous system pain amplification and may impact treatment response. Future research should examine whether this clinical phenotype predicts response to medical and behavioral treatments (e.g, anti-convulsants, behavioral therapy, Physical Therapy).

Quantitative Sensory Testing in Women After Surgery for Breast Cancer: A Systematic Review and Narrative Synthesis

OBJECTIVES

Quantitative sensory testing (QST) is a noninvasive technique to evaluate functioning of the somatosensory system. In many women surgically treated for breast cancer (BC), somatosensory functioning is disturbed with high prevalence of sensory loss and/or pain. The aims of this systematic review were (1) to summarize literature about QST methods; (2) to summarize the results within women surgically treated for BC (patients and survivors); (3) to compare QST results between women surgically treated for BC with and without pain; and (4) to compare the results between women surgically treated for BC and women without history of BC.

METHODS

A systematic literature search was conducted up to February 2020. Included studies had to report on QST methods (mechanical or thermal detection-pain thresholds, pressure pain thresholds [PPT], temporal summation [TS], or conditioned pain modulation [CPM]) in women over 18 years with-without pain, who had undergone unilateral surgery for BC.

RESULTS

Twenty-eight studies were included. Discrepancies in QST methods were greatest for TS and CPM. A local disturbance in thermal detection and an increased pain facilitation were found in BC survivors with pain in the surgical area. BC survivors with upper limb pain had significantly lower PPT at the surgical area and PPT were also significantly lower compared with women without history of BC, at affected and nonaffected sides for both local and remote body regions.

DISCUSSION

Standardized QST incorporating assessments of CPM is warranted in order to draw conclusions about neurobiological mechanisms of pain and somatosensory disturbances after surgical treatment for BC and to enhance mechanism-based management of these sequelae.

The Use of Quantitative Sensation Testing to Identify the Physiological Differences Between the Median and Ulnar Nerves

Introduction

Similarities in morphology, physiological function, and neurophysiological findings between median and ulnar nerves are not unequivocal. Our previous study confirmed differences in motor fiber parameters between these nerves in healthy persons. We made an attempt to assess and compare the physiological parameters of different sensation modalities (temperature, pain, and vibration) in median and ulnar nerves.

Methods

The study was performed in 31 healthy, right-handed volunteers: 17 women, 14 men, mean age 44.8 ± 15.5 years. Standard sensory conduction tests in the median and ulnar nerves were performed together with the estimation of vibratory, temperature, and warm- and cold-induced pain thresholds in the C7 and C8 dermatomes on the palm, using quantitative sensory testing.

Results

There were no statistically significant differences in the standard sensory conduction test in the median and ulnar nerves across the whole group: between right and left hands, and between women and men. We revealed differences in the temperature and pain thresholds between these nerves, mainly in low temperature perception. There were no differences in estimated thresholds between sides or in female and male groups. The vibratory limits did not differ significantly between nerves, and subgroups.

Conclusion

The study confirmed the differences in the physiological sensory perception between the median and ulnar nerves. The median nerve is more sensitive to temperature stimulation than the ulnar nerve, but simultaneously less sensitive to pain-inducing temperature stimuli. These findings should be considered during the examination of hand nerve pathology.

Associations of Small Fiber Neuropathy with Geriatric Nutritional Risk Index and Arterial Stiffness in Hemodialysis

BACKGROUND

Peripheral neuropathy is a common neurological complication in uremic patients, and quantitative sensory testing (QST) is effective for diagnosis of small fiber neuropathy. Malnutrition and arterial stiffness are prevalent in patients undergoing hemodialysis (HD). The associations of small fiber neuropathy with nutritional status and arterial stiffness remain uncertain in maintenance HD patients.

METHODS

A total of 152 HD patients were included. Geriatric nutritional risk index (GNRI), an indicator of nutritional status, was calculated by serum albumin and actual and ideal body weight. Arterial stiffness was defined as brachial-ankle pulse wave velocity (baPWV) > 1400 cm/s. Small fiber neuropathy was assessed by an abnormal QST threshold of cold and warm sensation in patients' hands or feet. Multivariate forward logistic regression analysis was performed to examine the associations among abnormal QST threshold, GNRI, and arterial stiffness.

RESULTS

baPWV and prevalence of abnormal QST threshold were significantly higher in diabetic patients. Multivariate logistic analyses revealed that older age (OR, 1.081; 95% CI, 1.026-1.139, p = 0.003) and male gender (OR, 4.450; 95% CI, 1.250-15.836, p = 0.021) were associated with abnormal warm threshold of hands. Furthermore, diabetes (OR, 3.966; 95% CI, 1.351-11.819, p = 0.012) and lower GNRI (per 1 unit increase, OR, 0.935, 95% CI, 0.887-0.985, p = 0.012) were associated with abnormal cold threshold of feet. Arterial stiffness (OR, 5.479, 95% CI, 1.132-22.870, p = 0.020) and higher calcium-phosphorus product (OR, 1.071, 95% CI, 1.013-1.132, p = 0.015) were associated with abnormal warm threshold of feet.

CONCLUSIONS

Lower GNRI and arterial stiffness were significantly associated with small fiber neuropathy in patients undergoing HD. Malnutrition risk and vascular factors might play important roles in small fiber neuropathy among patients undergoing HD.

The impact of chronic co-exposure to different heavy metals on small fibers of peripheral nerves. A study of metal industry workers

Background

Chronic exposure to heavy metals affects various organs, among them the brain and peripheral nerves. Polyneuropathy is mainly length-dependent with predominantly sensory symptoms. There have been few studies on small fiber neuropathy due to heavy metal intoxication.

Methods

We investigated 41 metal industry workers, mean age 51.3 ± 10.5 years, with at least 5 years’ professional exposure to heavy metals, and 36 age- and sex-matched healthy controls. We performed neurological examinations, and assessed blood levels of cadmium, lead, and zinc protoporphyrin, urine levels of arsenic, standard, sensory and motor electrophysiological tests in the ulnar and peroneal nerves, sympathetic skin responses from the palm and foot, and quantitative sensation testing from dermatomes C8 and S1.

Discussion

The results of standard conduction tests of all nerves significantly differed between groups. The latency of sympathetic skin responses achieved from the foot was also statistically significantly prolonged in the study group. Significant differences were seen in both C8 and S1 regions for temperature and pain thresholds, and for vibratory threshold only in the S1 region, while the dispersions of low and high temperatures were important exclusively in the C8 region.

Conclusions

We can conclude that co-exposure to many heavy metals results in explicit impairment of peripheral nerves. The lesion is more pronounced within small fibers and is predominantly connected with greater impairment of temperature-dependent pain thresholds. The evaluation of small fiber function should be considered in the early diagnosis of toxic polyneuropathy or in low-dose exposure to heavy metals.

Clinical study of diabetic peripheral neuropathy screening by retinal vascular geometric parameters

To investigate the relationship between geometrical changes of retinal vessels and diabetic peripheral neuropathy (DPN), and to determine the effectiveness of retinal vascular geometry analysis and vibration perception threshold (VPT) for DPN assessment. Type 2 diabetes patients (n = 242) were categorized by stage of DPN. VPT and fundus photography was performed to obtain retinal vascular geometry parameters. The risk factors for DPN and the correlation between DPN stages were analyzed. The efficiency of the retinal vascular geometric parameters obtained with VPT as a diagnostic tool for DPN was examined. Stages of DPN showed a linear correlation with VPT (r = 0.818), central retinal vein equivalent (CRVE) (r = 0.716), and fractal dimension arterioles (DFa) (r = - 0.769). VPT, CRVE, DFa, and fractal dimension veins (DFv) showed high sensitivity (80%, 55%, 82%, and 67%, respectively) and specificity (92%, 93%, 82%, and 80%, respectively) for DPN diagnosis. Good agreement was observed between combined use of geometric parameters (CRVE, DFa and DFv) and VPT (Kappa value 0.430). The detection rate of DPN with combined use of geometric parameters of retinal vessels (64.88%) was significantly higher than that with use of VPT (47.52%). Retinal vascular geometry changes demonstrated significant correlation with DPN severity. VPT, CRVE, DFa, and DFv may provide insights for understanding DPN.

Small Fiber Neuropathy in the Elderly

Small fiber neuropathy is common and prevalent in the elderly. The disease can be associated with many medical conditions. It often has a negative impact on quality of life due to painful paresthesia, dizziness, and sedative side effects of pain medications. Skin biopsy is the gold standard diagnostic test. Screening for associated conditions is important, because etiology-specific treatment can slow down disease progression and ameliorate symptoms. Adequate pain control can be challenging due to safety and tolerability of pain medications in the elderly. Treatment should be individualized with the goals of controlling underlying causes, alleviating pain, and optimizing daily function.

Early Detection of Diabetic Peripheral Neuropathy: A Focus on Small Nerve Fibres

Diabetic peripheral neuropathy (DPN) is the most common complication of both type 1 and 2 diabetes. As a result, neuropathic pain, diabetic foot ulcers and lower-limb amputations impact drastically on quality of life, contributing to the individual, societal, financial and healthcare burden of diabetes. DPN is diagnosed at a late, often pre-ulcerative stage due to a lack of early systematic screening and the endorsement of monofilament testing which identifies advanced neuropathy only. Compared to the success of the diabetic eye and kidney screening programmes there is clearly an unmet need for an objective reliable biomarker for the detection of early DPN. This article critically appraises research and clinical methods for the diagnosis or screening of early DPN. In brief, functional measures are subjective and are difficult to implement due to technical complexity. Moreover, skin biopsy is invasive, expensive and lacks diagnostic laboratory capacity. Indeed, point-of-care nerve conduction tests are convenient and easy to implement however questions are raised regarding their suitability for use in screening due to the lack of small nerve fibre evaluation. Corneal confocal microscopy (CCM) is a rapid, non-invasive, and reproducible technique to quantify small nerve fibre damage and repair which can be conducted alongside retinopathy screening. CCM identifies early sub-clinical DPN, predicts the development and allows staging of DPN severity. Automated quantification of CCM with AI has enabled enhanced unbiased quantification of small nerve fibres and potentially early diagnosis of DPN. Improved screening tools will prevent and reduce the burden of foot ulceration and amputations with the primary aim of reducing the prevalence of this common microvascular complication.

The time to develop treatments for diabetic neuropathy

BACKGROUND

Diabetic neuropathy is a multifaceted condition affecting up to 50% of individuals with long standing diabetes. The most common presentation is peripheral diabetic sensory neuropathy (DPN).

METHODS

We carried out a systematic review of papers dealing with diabetic neuropathy on Pubmed in addition to a targeted Google search.Search terms included small fiber neuropathy,diffuse peripheral neuropathy, quantitative sensory testing, nerve conduction testing, intra-epidermal nerve fiber density, corneal confocal reflectance microscopy, aldose reductase inhbitors, nerve growth factor, alpha-lipoic acid, ruboxistaurin, nerve growth factor antibody, and cibinetide.

RESULTS

Over the past half century, there have been a number of agents undergoing unsuccessful trials for treatment of DPN.There are several approved agents for relief of pain caused by diabetic neuropathy, but these do not affect the pathologic process.

EXPERT OPINION

The failure to find treatments for diabetic neuropathy can be ascribed to (1) the complexity of design of studies and (2) the slow progression of the condition, necessitating long duration trials to prove efficacy.We propose a modification of the regulatory process to permit early introduction of agents with demonstrated safety and suggestion of benefit as well as prolongation of marketing exclusivity while long term trials are in progress to prove efficacy.

Lost in Translation? Measuring Diabetic Neuropathy in Humans and Animals

The worldwide diabetes epidemic is estimated to currently afflict almost 500 million persons. Long-term diabetes damages multiple organ systems with the blood vessels, eyes, kidneys and nervous systems being particularly vulnerable. These complications of diabetes reduce lifespan, impede quality of life and impose a huge social and economic burden on both the individual and society. Peripheral neuropathy is a debilitating complication that will impact over half of all persons with diabetes. There is no treatment for diabetic neuropathy and a disturbingly long history of therapeutic approaches showing promise in preclinical studies but failing to translate to the clinic. These failures have prompted re-examination of both the animal models and clinical trial design. This review focuses on the functional and structural parameters used as indices of peripheral neuropathy in preclinical and clinical studies and the extent to which they share a common pathogenesis and presentation. Nerve conduction studies in large myelinated fibers have long been the mainstay of preclinical efficacy screening programs and clinical trials, supplemented by quantitative sensory tests. However, a more refined approach is emerging that incorporates measures of small fiber density in the skin and cornea alongside these traditional assays at both preclinical and clinical phases.

Non-invasive brain stimulation as a tool to decrease chronic pain in current opiate users: A parametric evaluation of two promising cortical targets

BACKGROUND

Poorly controlled chronic pain can lead to non-prescription use of opiates, which is a growing crisis in our communities. Transcranial magnetic stimulation (TMS) is a non-invasive therapeutic tool which has emerged as a potential treatment option for these patients. It is still unclear, however, if the dorsolateral prefrontal cortex (DLPFC) or the motor cortex (MC) is a more effective treatment location. The purpose of this study was to directly compare the effects of DLPFC versus MC TMS on pain severity and the urge to use opiates among chronic pain patients.

METHODS

Twenty-two individuals with chronic pain currently using prescription opiates were randomized to receive 10, 3000 pulse sessions of 10 Hz repetitive TMS (rTMS) to the left DLPFC (110% resting motor threshold) or left MC (90% resting motor threshold). Multivariate linear models were used to evaluate the effect of TMS on pain and opiate use, including items from the Brief Pain Inventory (BPI) as well as subjective ratings of pain, distress, and the urge for opiates.

RESULTS

Twenty participants (91%) completed all 10 treatment sessions and follow up visits. There was a main effect of stimulation site (F7,210 = 3.742, p = 0.001), wherein MC stimulation decreased pain interference significantly more than DLPFC stimulation (F_1,216 = 8.447, p = 0.004). While both sites had comparable effect sizes on stress, pain, and discomfort, MC stimulation had larger effects on pain interference (Cohen's d: 0.7) and urge to use opiates (Cohen's d: 0.5) than DLPFC stimulation.

CONCLUSION

These data suggest that the MC may be a promising target for decreasing opiate dependence and pain interference among chronic pain patients.

Electronic von Frey as an objective assessment tool for oxaliplatin-induced peripheral neuropathy: A prospective longitudinal study

OBJECTIVE

There is wide discrepancy on how to perform clinical assessment of oxaliplatin-induced peripheral neuropathy. In this scenario, the Electronic von Frey (EVF), which evaluates pain objectively based upon mechanical pain thresholds (MPTs), may be a valuable tool. The present study aims to quantify hyperalgesia in the hands and feet of patients treated with oxaliplatin and to propose a novel method to classify the degree of neurotoxicity using EVF-derived measures as cut-off points.

METHODS

This is a prospective cohort study including 46 patients treated for colorectal cancer with the FLOX regimen. Before each oxaliplatin administration, patients were evaluated with the Acute and Chronic Neuropathy Questionnaire, Oxaliplatin-Specific Neurotoxicity Scale and National Cancer Institute Common Terminology Criteria for Adverse Events scale. Also, objective pain assessment with the EVF was performed.

RESULTS

For both upper and lower extremities, EVF was shown to correlate well with patients' symptoms and functional impairment, as assessed by subjective scales. Also, when cut-off MPT variations were determined for diagnosis of neurotoxicity grade 2 or 3, the method showed good sensitivity and specificity.

CONCLUSION

Electronic von Frey is a noninvasive and easy-to-perform objective method with potential to supplement the current assessment tools for oxaliplatin-induced peripheral neuropathy, which are mostly subjective.

Vibration threshold in non-diabetic subjects

Measuring vibration perception threshold (VPT) accurately classifies and quantifies the severity of loss of vibration perception. A biothesiometer (Bio-thesiometer®; Bio Medical Instrument Co, Ohio, USA) appears to be the most suitable tool to determine VPT due to its low inter-rater variability and low occurence of adaption to the sensation. Different VPT values for a biothesiometer have been described, however, specification on age, height and different measurement locations is currently lacking. The objective of our study was to identify determinants of vibration perception in non-diabetic subjects, in order to provide individualized normal values of VPTs for clinical practice. Measurements of the vibration perception were performed on the big toes, insteps, lateral malleoli, and wrists. A total of 205 healthy subjects were included (108 (52.7%) males) with a median [interquartile range] age of 59 [51;64] (range 21-80) years. Mean height was 174.45 ± 9.20 cm and mean weight was 82.94 ± 14.84 kg, resulting in a mean BMI of 27.19 ± 4.00 kg/m2. In stepwise forward linear regression analyses, age (st. β = 0.51, p < 0.001) and height (st. β = 0.43, p < 0.001) were found to be the independent unmodifiable determinants of the VPT at the big toe. Regression coefficients for quantiles of the determinants age and height were incorporated in the corresponding regression equations. This study provides equations to calculate age- and height-specific normal values for VPT that can be used in clinical practice and in large research studies.

Clinical spectrum and diagnosis of diabetic neuropathies

Neuropathy is the most prevalent microvascular complication of diabetes mellitus; it encompasses distal symmetric polyneuropathy, autonomic neuropathy, radiculoplexus neuropathy, mononeuropathy, and treatment-induced neuropathy. The prevalence rate of diabetic neuropathy in Korea was reported to be approximately 43%, which is similar to rates in other countries. However, the precise pathogenic mechanism underlying diabetic neuropathy is still obscure, and many clinical trials have failed to develop methods to prevent or reduce the progression of diabetic neuropathy. Nevertheless, early diagnosis and proper management of diabetic neuropathy are essential to alleviate disabling symptoms and to improve the quality of life of patients. This review discusses clinical manifestations and classification of diabetic neuropathies, bedside neurological examination, and electrophysiological tests.

Diabetic Peripheral Neuropathy: Diagnosis and Treatment

BACKGROUND

Diabetic peripheral neuropathy (DPN) is traditionally divided into large and small fibre neuropathy (SFN). Damage to the large fibres can be detected using nerve conduction studies (NCS) and often results in a significant reduction in sensitivity and loss of protective sensation, while damage to the small fibres is hard to reliably detect and can be either asymptomatic, associated with insensitivity to noxious stimuli, or often manifests itself as intractable neuropathic pain.

OBJECTIVE

To describe the recent advances in both detection, grading, and treatment of DPN as well as the accompanying neuropathic pain.

METHODS

A review of relevant, peer-reviewed, English literature from MEDLINE, EMBASE and Cochrane Library between January 1st 1967 and January 1st 2020 was used.

RESULTS

We identified more than three hundred studies on methods for detecting and grading DPN, and more than eighty randomised-controlled trials for treating painful diabetic neuropathy.

CONCLUSION

NCS remains the method of choice for detecting LFN in people with diabetes, while a gold standard for the detection of SFN is yet to be internationally accepted. In the recent years, several methods with huge potential for detecting and grading this condition have become available including skin biopsies and corneal confocal microscopy, which in the future could represent reliable endpoints for clinical studies. While several newer methods for detecting SFN have been developed, no new drugs have been accepted for treating neuropathic pain in people with diabetes. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors and anticonvulsants remain first line treatment, while newer agents targeting the proposed pathophysiology of DPN are being developed.

Association between TUG and Anthropometric Values, Vibration Perception Threshold, FHSQ and 15-D in Type 2 Diabetes Mellitus Patients

Background: Diabetes Mellitus (DM) is a chronic disease and it is characterized by reduced insulin sensitivity and/or impaired insulin production. It affects approximately 415 million people worldwide and involves a variety of complications. DM has a number of complications, including diabetic neuropathy. All of these complications can have effects on body composition, vibration perception threshold (VPT), foot health and health-related quality of life (HRQoL). Objective: The aim of this study is to determine the correlation between the Timed Up and Go (TUG), VPT, Foot Health Status Questionnaire and 15-D Questionnaire in type 2 diabetes mellitus (T2DM) patients. Methodology: A total of 90 T2DM patients (56 men and 34 women) were evaluated on their body composition, VPT, the foot health status through the FHSQ, the HRQoL was evaluated through the 15-D Questionnaire and the TUG test was performed. Results: Statistically significant associations were found between TUG and lean and fat mass, VPT, the sections "General Foot Health" and "Physical Activity" in the FHSQ questionnaire, and the 15D total score and its sections "Mobility" and "Depression". Conclusions: There is a moderate direct correlation between the Timed Up and Go and the fat mass percentage and the vibration perception threshold. Moreover, there is a moderate inverse correlation between Timed Up and Go and fat-free mass, foot health and health-related quality of life in T2DM patients. Therefore, Timed Up and Go can be a tool to assist clinicians in monitoring and managing T2DM patients.

Quantitative Sensory Testing in Patients with Multisomatoform Disorder with Chronic Pain as the Leading Bodily Symptom-a Matched Case-Control Study

OBJECTIVE

Chronic pain is a debilitating condition of multifactorial origin, often without physical findings to explain the presenting symptoms. Of the possible etiologies of persisting painful symptoms, somatoform disorders and functional somatic syndromes (FSS) are among the most challenging, with a prevalence of 8-20%. Many different somatoform disorders and FSS have overlapping symptoms, with pain being the most prevalent one. The concept of multisomatoform disorder (MSD) has been developed to acknowledge that fact. We hypothesized that the concept of MSD will be reflected in a distinct sensory profile of patients compared with healthy controls and possibly provide insight into the type and pathophysiology of the pain commonly experienced by patients.

DESIGN

We performed comprehensive quantitative sensory testing (QST) in 151 patients and 149 matched controls.

RESULTS

There were significant differences in the sensory profiles of patients compared with controls. Patients with MSD showed a combination of tactile and thermal hypesthesia combined with mechanical and cold hyperalgesia. This was true for measurements at test and control sites, with the exception of vibration detection threshold and mechanical pain threshold. Among the observed changes, a marked sensory loss of function, as evidenced by an increase in cold detection threshold, and a marked gain of function, as evidenced by a decrease of pressure pain threshold, were most notable. There was no evidence of concurrent medication influencing QST results.

CONCLUSIONS

The observed somatosensory profile of patients with MSD resembles that of patients suffering from neuropathic pain with evidence of central sensitization.

Local and Systemic Analgesic Effects of Nerve-Specific Acupuncture in Healthy Adults, Measured by Quantitative Sensory Testing

OBJECTIVE

This study aims to assess whether acupuncture analgesia's effects are local or systemic and whether there is a dose response for these effects.

METHODS

Twenty-eight healthy volunteers aged 18-45 were randomized to two doses of acupuncture using points closely associated with peripheral nerves in the legs. The lower-dose group involved acupoints overlying the deep peroneal nerve (DP), and the higher-dose involved acupoints overlying the deep peroneal and posterior tibial nerves (DPTN). Baseline and acupuncture quantitative sensory testing (QST) assessments were obtained locally in the calf and great toe and systemically in the hand. Results were analyzed using factorial repeated-measures analysis of variance for each of the QST variables-cold detection threshold (CDT), vibration detection threshold (VDT), heat pain threshold (HP0.5), and heat pain perception of 5/10 (HP5.0). Location (leg/hand) and time (baseline/acupuncture) were within-subject factors. Intervention (DP/DPTN) was a between-subject factor.

RESULTS

CDT was increased in the calf (P < 0.001) and in the hand (P < 0.001). VDT was increased in the toe (P < 0.001) but not in the hand. HP0.5 was increased in the calf (P < 0.001) and in the hand (P < 0.001). HP5.0 was increased in the calf (P = 0.002) and in the hand (P < 0.001), with the local effect being significantly greater than the systemic (P = 0.004). In all of the above QST modalities, there was no difference between the low-dose (DP) and high-dose (DPTN) acupuncture groups.

CONCLUSIONS

Acupuncture caused comparable local and systemic analgesic effects in cold detection and heat pain perception and only local effects in vibration perception. There was no clear acupuncture dose response to these effects.

Reduced TRPM8 expression underpins reduced migraine risk and attenuated cold pain sensation in humans

Multiple genome-wide association studies have identified non-coding single-nucleotide variants (SNVs) near (e.g., rs10166942[C]) or within (rs17862920[T]) the TRPM8 gene that encodes a cold thermosensor is associated with reduced migraine risk. Furthermore, rs10166942[C]) and rs10166942[T]) are more prevalent in populations that reside in hotter and colder climates, respectively. Here we assessed whether these alleles affect TRPM8 expression in humans and human physiologic responses to cold challenge. Here we show that TRPM8 expression is decreased from the chromosome harboring the rs10166942[C] allele in the human dorsal root ganglia. Moreover, carriers of rs10166942[C] required significantly lower temperatures and longer duration of exposure to reach a cold pain threshold (CPTh), which correlated with decreased TRPM8 expression expected in the carriers. This study provides evidence for a genotype-dependent influence on cold pain sensation suggesting that carriers of the reduced migraine risk allele have reduced sensitivity to cold stimuli and that TRPM8 acts as a cold thermosensor and cold pain transducer in humans. Reduced TRPM8 expression and function underpins the migraine protection in carriers of rs10166942[C]; thus, the evaluation of TRPM8 antagonists as migraine therapeutics is warranted. Furthermore, these results provide mechanistic insights for evolutionary positive selection of rs10166942[T] allele in adaptation along latitudinal cline to colder climates.

Endometriosis and pain in the adolescent- striking early to limit suffering: A narrative review

Endometriosis, a condition in which uterine tissue grows outside the uterus, is a debilitating disease, affecting millions of women and costing the United States approximately $78 billion annually in pain- related disability. It is also the leading cause of chronic pelvic pain (CPP), which is often unresponsive to existing treatments. Adolescent women with the disease are at particular risk as there are often significant diagnostic delays, which in turn can exacerbate pain. Research and treatment guidelines for adolescents with endometriosis are largely based on studies for adult women due to the limited number of studies focusing on adolescents. The current paper critically reviews the literature as it pertains to endometriosis pathophysiology, mechanisms contributing to CPP, and treatment implications and recommendations with a focus on gaps related to adolescents.

Relationship of Pain Quality Descriptors and Quantitative Sensory Testing: Sickle Cell Disease

BACKGROUND

Chronic pain in adults with sickle cell disease (SCD) may be the result of altered processing in the central nervous system, as indicated by quantitative sensory testing (QST). Sensory pain quality descriptors on the McGill Pain Questionnaire (MPQ) are indicators of typical or altered pain mechanisms but have not been validated with QST-derived classifications.

OBJECTIVES

The specific aim of this study was to identify the sensory pain quality descriptors that are associated with the QST-derived normal or sensitized classifications. We expected to find that sets of sensory pain quality descriptors would discriminate the classifications.

METHODS

A cross-sectional quantitative study of existing data from 186 adults of African ancestry with SCD. Variables included MPQ descriptors, patient demographic data, and QST-derived classifications.

RESULTS

The participants were classified as central sensitization (n = 33), mixed sensitization (n = 23), and normal sensation. Sensory pain quality descriptors that differed statistically between mixed sensitization and central sensation compared to normal sensitization included cold (p = .01) and spreading (p = .01). Aching (p = .01) and throbbing (p = .01) differed statistically between central sensitization compared with mixed sensitization and normal sensation. Beating (p = .01) differed statistically between mixed sensitization compared with central sensitization and normal sensation. No set of sensory pain quality descriptors differed statistically between QST classifications.

DISCUSSION

Our study is the first to examine the association between MPQ sensory pain quality descriptors and QST-derived classifications in adults with SCD. Our findings provide the basis for the development of a MPQ subscale with potential as a mechanism-based screening tool for neuropathic pain.

Quantitative sensory testing to evaluate and compare the results after epidural injection and simple discectomy, in patients with radiculopathy secondary to lumbar disc herniation

The objective assessment of the radiculopathy secondary to lumbar disc herniation is essential to optimize treatment. The quantitative sensory test (QST) is a useful tool to evaluate somatosensory nerves. The aim of our study is quantifying by QST the alterations of patients treated by epidural injections (EI) or surgical lumbar decompression (LD). A prospective, cohort study has done in Hospital Universitario Rio Hortega, Valladolid, Spain, between January 2014 and December 2016.The study includes 74 patients (40 men) who underwent EI (50) or LD (24) with lumbar disc herniation and treated by EI or LD. Participants underwent a brief battery of QST at baseline and after 1, 3 and 6 months of follow-up. QST threshold were measured in three series of five warm and cold stimuli (cold detection threshold, warm detection threshold, cold pain threshold, heat pain threshold) bilateral. Additionally, pain assessment (Visual Analogue Scale) and neurological examination was performed. Thermal thresholds were analysed and compared. In the EI group, warm detection threshold (WDT) measurements were significantly lower after 3 and 6 months of follow-up (40.44 ± 3.42°C vs. 38.30 ± 3.73°C and 37.48 ± 4.58°C respectively, p = 0.031 and p = 0.043). LD group showed lower WDT measurements at 1, 3 and 6 months of follow up (40.20 ± 2.97°C vs., 37.98 ± 2.04°C, 37.43 ± 3.80°C and 36.55 ± 2.77°C respectively, p = 0.049, p = 0.032 and p = 0.024) and lower heat pain threshold (HPT) levels after 3 and 6 months of follow-up (48.75 ± 1.37°C vs. 43.26 ± 0.60°C and 42.06 ± 1.37°C respectively, p = 0.037 and p = 0.021). QST explorations were compared between both groups. At 1-month follow-up only the WDT parameter was different, higher in EI group (40.98 ± 4.04°C vs. 37.98 ± 2.04°C, p = 0.043). There were no differences in any parameter measured by QST after 3 and 6-months follow-up between both groups. Epidural injection should be considered the first-step of treatment.

Quantification of Small Fiber Neuropathy in Chemotherapy-Treated Patients

Chemotherapy-induced peripheral neuropathy (CIPN) is a major, dose-limiting side effect of treatment with neurotoxic cancer treatments which can result in long-term impairment. Deficits often reflect a large fiber polyneuropathy, however small fiber involvement resulting in neuropathic pain and autonomic dysfunction can occur. Quantification of both CIPN and small fiber neuropathy (SFN) remains a challenge. Accordingly, the prevalence and pathophysiology of small fiber neuropathy amongst cancer survivors remains poorly understood. This review will provide an overview of the clinical features of SFN associated with neurotoxic cancer treatments as well as a summary of current assessment tools for evaluating small fiber function, and their use in patients treated with neurotoxic chemotherapies. The continued development and utilization of novel measures quantifying small fiber involvement will help elucidate the pathophysiology underlying symptoms of CIPN and assist in informing treatment approaches. Accurately identifying subgroups of patients with neuropathic symptoms which may respond to existing pain medication may reduce the impact of CIPN and improve long-term quality of life as well as provide better categorization of patients for future clinical trials of neuroprotective and treatment strategies for CIPN. PERSPECTIVE: This review provides a critical analysis of SFN associated with neurotoxic cancer treatments and the assessment tools for evaluating small fiber dysfunction in cancer patients. Quantification of small fiber involvement in CIPN will assist in identifying subgroups of patients with neuropathic symptoms which may respond to existing pain medications.

Reproducibility of a battery of human evoked pain models to detect pharmacological effects of analgesic drugs

BACKGROUND

Although reproducibility is considered essential for any method used in scientific research, it is investigated only rarely; thus, strikingly little has been published regarding the reproducibility of evoked pain models involving human subjects. Here, we studied the reproducibility of a battery of evoked pain models for demonstrating the analgesic effects of two analgesic compounds.

METHODS

A total of 81 healthy subjects participated in four studies involving a battery of evoked pain tests in which mechanical, thermal and electrical stimuli were used to measure pain detection and tolerance thresholds. Pharmacodynamic outcome variables were analysed using a mixed model analysis of variance, and a coefficient of variation was calculated by dividing the standard deviation by the least squares means.

RESULTS

A total of 76 subjects completed the studies. After being administered pregabalin, the subjects' pain tolerance thresholds in the cold pressor and pressure stimulation tests were significantly increased compared to the placebo group. Moreover, the heat pain detection threshold in UVB-irradiated skin was significantly increased in subjects who were administered ibuprofen compared to the placebo group. Variation among all evoked pain tests ranged from 2.2% to 30.6%.

CONCLUSIONS

Four studies using a similar design showed reproducibility with respect to the included evoked pain models. The relatively high consistency and reproducibility of two analgesics at doses known to be effective in treating clinically relevant pain supports the validity of using this pain test battery to investigate the analgesic activity and determine the active dosage of putative analgesic compounds in early clinical development.

SIGNIFICANCE

The consistency and reproducibility of measuring the profile of an analgesic at clinically relevant doses illustrates that this pain test battery is a valid tool for demonstrating the analgesic activity of a test compound and for determining the optimal active dose in early clinical drug development.

Diagnosis and management of sensory polyneuropathy

Sensory polyneuropathies, which are caused by dysfunction of peripheral sensory nerve fibers, are a heterogeneous group of disorders that range from the common diabetic neuropathy to the rare sensory neuronopathies. The presenting symptoms, acuity, time course, severity, and subsequent morbidity vary and depend on the type of fiber that is affected and the underlying cause. Damage to small thinly myelinated and unmyelinated nerve fibers results in neuropathic pain, whereas damage to large myelinated sensory afferents results in proprioceptive deficits and ataxia. The causes of these disorders are diverse and include metabolic, toxic, infectious, inflammatory, autoimmune, and genetic conditions. Idiopathic sensory polyneuropathies are common although they should be considered a diagnosis of exclusion. The diagnostic evaluation involves electrophysiologic testing including nerve conduction studies, histopathologic analysis of nerve tissue, serum studies, and sometimes autonomic testing and cerebrospinal fluid analysis. The treatment of these diseases depends on the underlying cause and may include immunotherapy, mitigation of risk factors, symptomatic treatment, and gene therapy, such as the recently developed RNA interference and antisense oligonucleotide therapies for transthyretin familial amyloid polyneuropathy. Many of these disorders have no directed treatment, in which case management remains symptomatic and supportive. More research is needed into the underlying pathophysiology of nerve damage in these polyneuropathies to guide advances in treatment.