The H-Reflex as a Biomarker for Spinal Disinhibition in Painful Diabetic Neuropathy

Evidence for spinal disinhibition as a pain-generating mechanism in fibromyalgia syndrome

Introduction

Pain phenomenology in patients with fibromyalgia syndrome (FMS) shows considerable overlap with neuropathic pain. Altered neural processing leading to symptoms of neuropathic pain can occur at the level of the spinal cord, and 1 potential mechanism is spinal disinhibition. A biomarker of spinal disinhibition is impaired H-reflex rate-dependent depression (HRDD).

Objectives

This study investigated whether patients with FMS exhibit evidence of spinal disinhibition.

Methods

Thirty-one individuals with FMS and 20 healthy volunteers underwent testing of Hoffman reflex including HRDD, along with assessment of clinical signs and symptoms, pressure pain thresholds, temporal summation of pain (wind-up), and conditioned pain modulation (CPM). Small nerve fibre structure was quantified using intraepidermal nerve fibre density and corneal confocal microscopy.

Results

Patients with FMS had significantly impaired HRDD at 1 Hz (P = 0.026) and 3 Hz (P = 0.011) and greater wind-up ratio (P = 0.008) compared with healthy controls. Patients with the most impaired HRDD also had the most inefficient CPM but HRDD was not associated with wind-up. Both HRDD and CPM were most impaired in patients with a shorter duration of disease.

Conclusion

We demonstrate for the first time that people with FMS show evidence of spinal disinhibition, which is most dominant in shorter duration of disease and may represent a putative mechanism of pain generation in FMS. Identifying people with impairment of central pain processing at an early stage may provide opportunities for targeted mechanistically directed interventions. Longitudinal studies are warranted to tease out the precise contribution of these mechanisms.

Development of KCC2 therapeutics to treat neurological disorders

KCC2 is CNS neuron-specific chloride extruder, essential for the establishment and maintenance of the transmembrane chloride gradient, thereby enabling synaptic inhibition within the CNS. Herein, we highlight KCC2 hypofunction as a fundamental and conserved pathology contributing to neuronal circuit excitation/inhibition (E/I) imbalances that underly epilepsies, chronic pain, neuro-developmental/-traumatic/-degenerative/-psychiatric disorders. Indeed, downstream of both acquired and genetic factors, multiple pathologies (e.g., hyperexcitability and inflammation) converge to impair KCC2-dependent inhibition in CNS. When KCC2 hypofunction occurs, affected neurons are disinhibited due to impaired inhibitory responses to GABA/glycine. This causes neuronal hyperexcitability, disinhibition within neuron circuits, and disrupted neurological functions. More recently, KCC2 was identified as a genetically-validated target for epilepsy, intellectual disability, and autism spectrum disorder, and pathogenic mutations in human SLC12A5 gene were linked to psychiatric/mood disorders. The broad therapeutic utility of KCC2-upmodulating drugs relates to its critical role in determining inhibitory activity of GABAergic neurotransmission, a mechanism widely targeted by several drugs. However, in cases of KCC2 hypofunction GABAergic neurotransmission can be depolarizing/excitatory, thereby impairing endogenous neuronal inhibition while also limiting the effectiveness of existing therapeutics targeting/requiring GABAergic pathway inhibition. Several preclinical reports have shown that KCC2 upmodulating treatments rescue and increase the efficacy of anti-seizure and analgesic medications. Thus, a first-in-class KCC2-potentiating therapy would provide a novel mechanism for restoring physiological CNS inhibition and addressing drug resistance in patients with E/I imbalance pathologies. Herein, we discuss progress toward and further work needed to develop the first-in-class KCC2 therapeutics to treat neurological disorder patients.

The impact of socioeconomic deprivation on the prevalence of gestational diabetes: An observational study

Background

Approximately 3.5% of pregnancies in the United Kingdom are complicated by gestational diabetes mellitus (GDM). Risk factors for this mirror those contributing to type 2 diabetes (T2DM). Though socioeconomic status (SES) is presumed to contribute to GDM, evidence in the United Kingdom is limited. In this unique study, we explored the impact of SES on GDM prevalence in a London suburb population.

Materials and Methods

Four thousand one hundred and sixty-three pregnant women who booked between July 2018 and March 2020 at Princess Royal University Hospital were retrospectively analyzed. Associations between GDM prevalence and SES trends (using multiple deprivation deciles (MDD)), and body mass index (BMI), age, ethnicity, screening uptake, birth-weights and birth outcomes, were analyzed.

Results

Patients with BMI >30 kg/m2, older than 35 years, and non-Caucasian ethnicity have an increased risk of developing GDM (p < 0.0001, p < 0.0001, p < 0.0001, respectively). No association existed between MDD and GDM prevalence (p-values over 0.05). Patients with risk factors for GDM were highest in the deprived areas p < 0.0001. MDD 1-4 (most deprived) had the highest percentage of missed screening (15% of patients with risk factors missed screening), compared to 8% in the least deprived group (p < 0.0001).

Discussion

Our data surprisingly suggest that low SES did not increase the incidence of GDM, despite a higher proportion of women with risk factors for GDM living in the most deprived postcodes. However this unclear finding may be due to low screening uptake of deprived populations, and therefore lack of GDM diagnosis, or indicate that GDM is a result of a different aetiology to T2DM. Further research is needed to explore if access to screening services, lack of health education or other health inequalities were responsible for the high proportion of missed screening opportunities in deprived areas.

Rate-Dependent Depression of the Hoffmann Reflex: Practical Applications in Painful Diabetic Neuropathy

Measurement of the rate-dependent depression (RDD) of the Hoffmann (H) reflex, a technique developed over half a century ago, is founded on repeated stimulation of the H-reflex with tracking of sequentially evoked H-wave amplitudes in the resulting electromyogram. RDD offers insight into the integrity of spinal reflex pathways and spinal inhibitory regulation. Initially, RDD was predominantly utilized in the mechanistic exploration and evaluation of movement disorders characterized by spasticity symptoms, as may occur following spinal cord injury. However, there is increasing recognition that sensory input from the periphery is modified at the spinal level before ascending to the higher central nervous system and that some pain states can arise from, or be exaggerated by, disruption of spinal processing via a mechanism termed spinal disinhibition. This, along with the urgent clinical need to identify biological markers of pain generator and/or amplifier sites to facilitate targeted pain therapies, has prompted interest in RDD as a biomarker for the contribution of spinal disinhibition to neuropathic pain states. Current research in animals and humans with diabetes has revealed specific disorders of spinal GABAergic function associated with impaired RDD. Future investigations on RDD aim to further elucidate its underlying pathways and enhance its clinical applications.

The Effects of Acidified Nitrite on Wound Healing in Streptozotocin-Induced Diabetic Mice

Background

Diabetes mellitus (DM) is one of the most common metabolic diseases in the world. Studies have shown that nitric oxide (NO) promotes re-epithelialization and stimulates angiogenesis and neovascularization. This study aimed to investigate the effect of exogenous NO on diabetic wound healing.

Materials and Methods

This study was performed on 63 male BALB/c mice. For type 2 diabetes induction, the animals were fed a high-fat diet followed by a single dose of streptozotocin (STZ) (35 mg/kg) injection intraperitoneally. Acidified nitrite cream was prepared with 3.0% (w/v) sodium nitrite (SN) and 4.5% (w/v) citric acid monohydrate, respectively, in the aqueous cream base. Histopathological examinations were performed using hematoxylin and eosin and Masson's trichrome staining.

Results

The results showed that in the silver sulfadiazine-treated group, the size of the wound surface on the 7th day was significantly (P < 0.05) reduced compared to the control group. There was a significant (P < 0.005) decrease in the size of the wound in the SN-treated group on days 7 and 14 compared to the control group. The results of histopathological studies also showed that re-epithelialization and granulation in the diabetic wound site increased in the groups treated with acidified nitrite cream compared to other groups.

Conclusion

The use of topical acidified nitrite cream increases the speed of wound healing and it accelerates the healing of diabetic wounds in mice by causing a delay in the inflammation process and increasing the speed of re-epithelialization.

Exploring the interplay between emotional attitudes towards diabetes, eating behaviour and glycaemic control in patients with type 2 diabetes mellitus

OBJECTIVE

This study aimed to assess the association between emotional attitudes towards diabetes, eating behaviour styles and glycaemic control in outpatients with type 2 diabetes.

DESIGN

Observational study.

SETTING

Endocrinology Division of Hospital de Clínicas de Porto Alegre, Brazil.

PARTICIPANTS

Ninety-one outpatients diagnosed with type 2 diabetes. Baseline assessments included data on clinical parameters, lifestyle factors, laboratory results, eating behaviour styles and emotional attitudes. All patients received nutritional counseling following diabetes recommendations. A follow-up visit was scheduled approximately 90 days later to evaluate changes in weight, medication dosages and glycated Hb (HbA1c) values. Patients were categorised based on their emotional attitude scores towards diabetes (positive or negative), and their characteristics were compared using appropriate statistical tests.

RESULTS

At baseline, no differences were observed in the proportion of patients with good glycaemic control, eating behaviour styles and emotional attitudes. However, patients with a positive attitude towards the disease exhibited a significantly better response in glycaemic control compared with the reference group (OR = 3·47; 95 % CI = 1·12, 10·75), after adjusting for diabetes duration, sex and medication effect score. However, when BMI was included in the model, the association did not reach statistical significance. Therefore, these results should be interpreted with caution.

CONCLUSIONS

Patients with a positive attitude towards diabetes showed a greater reduction in HbA1c levels following nutritional counseling. However, baseline BMI could be a potential confounding factor.

A preliminary study exploring the effects of transcutaneous spinal cord stimulation on spinal excitability and phantom limb pain in people with a transtibial amputation

Objective. Phantom limb pain (PLP) is debilitating and affects over 70% of people with lower-limb amputation. Other neuropathic pain conditions correspond with increased spinal excitability, which can be measured using reflexes andF-waves. Spinal cord neuromodulation can be used to reduce neuropathic pain in a variety of conditions and may affect spinal excitability, but has not been extensively used for treating PLP. Here, we propose using a non-invasive neuromodulation method, transcutaneous spinal cord stimulation (tSCS), to reduce PLP and modulate spinal excitability after transtibial amputation.Approach. We recruited three participants, two males (5- and 9-years post-amputation, traumatic and alcohol-induced neuropathy) and one female (3 months post-amputation, diabetic neuropathy) for this 5 d study. We measured pain using the McGill Pain Questionnaire (MPQ), visual analog scale (VAS), and pain pressure threshold (PPT) test. We measured spinal reflex and motoneuron excitability using posterior root-muscle (PRM) reflexes andF-waves, respectively. We delivered tSCS for 30 min d-1for 5 d.Main Results. After 5 d of tSCS, MPQ scores decreased by clinically-meaningful amounts for all participants from 34.0 ± 7.0-18.3 ± 6.8; however, there were no clinically-significant decreases in VAS scores. Two participants had increased PPTs across the residual limb (Day 1: 5.4 ± 1.6 lbf; Day 5: 11.4 ± 1.0 lbf).F-waves had normal latencies but small amplitudes. PRM reflexes had high thresholds (59.5 ± 6.1μC) and low amplitudes, suggesting that in PLP, the spinal cord is hypoexcitable. After 5 d of tSCS, reflex thresholds decreased significantly (38.6 ± 12.2μC;p< 0.001).Significance. These preliminary results in this non-placebo-controlled study suggest that, overall, limb amputation and PLP may be associated with reduced spinal excitability and tSCS can increase spinal excitability and reduce PLP.

Compositional profiling and bioefficacy studies of pulses-supplemented isocaloric designer biscuits for recently diagnosed diabetic individuals

This study addresses global concerns about diabetes mellitus by exploring a novel approach to manage hyperglycemia through pulses-supplemented designer biscuits. Control and designer biscuits were prepared with varying proportions of wheat flour and pulses (chickpea, mungbean). The pulses-supplemented biscuits exhibited increased protein content and reduced readily available carbohydrates. Selected designer biscuits, with 12.5 % incorporation of chickpea and mungbean pulse flour, demonstrated significantly lower glycemic index (69.17 ± 5.01) and higher satiety index (122.19 ± 8.85) compared to control biscuits. These showed 13 % less glycemic index and 9 % higher satiety index as compared to control biscuits. A four-week bio-efficacy trial involving diabetic subjects consuming these biscuits as a routine snack resulted in an 11.45 % decrease in fasting blood glucose and a 19.15 % reduction in random blood glucose levels. Insulin and HDL levels also significantly improved. The study concludes that these designer biscuits possess a hypoglycemic effect, offering a potential dietary intervention for managing diabetes.

Lifestyle modification for mental health and well-being

Background

Unhealthy life-style leads to mental ill-health and poor quality of life and is the major determinant of a wide range of lifestyle disorders. The aim was to 1) review the work relating to life style modification for promoting mental health and 2) Present recommendations on life-style modification for mental health and wellbeing.

Material and Methods

The work on life style changes for promotion of mental health was retrieved from the scientific literature and critically reviewed.

Conclusions

Recommendations on 'Life-style modification for mental health and wellbeing' are presented. 20 specific components of healthy life style included are: Routine, time management, prayer, basic activities, reading newspaper, study/work, exercise, recreation/ relaxation/ talent promotion, education, cognitive activities, social networking, guidelines for behavior, peer group, social group, marriage/family, life skills, physical health, health education, mobile use, and digital media. The lifestyle modification package is comprehensive and geared to promote mental health and well-being.

From brain to spinal cord: neuromodulation by direct current stimulation and its promising effects as a treatment option for restless legs syndrome

Neuromodulation is a fast-growing field of mostly non-invasive therapies, which includes spinal cord stimulation (SCS), transcranial direct current stimulation (tDCS), vagal nerve stimulation (VNS), peripheral nerve stimulation, transcranial magnetic stimulation (TMS) and transcutaneous spinal direct current stimulation (tsDCS). This narrative review offers an overview of the therapy options, especially of tDCS and tsDCS for chronic pain and spinal cord injury. Finally, we discuss the potential of tsDCS in Restless Legs Syndrome as a promising non-invasive, alternative therapy to medication therapy.

Enhancing Diabetes Care in LMICs: Insights from a Multinational Consensus

The International Cardio-Metabolic Forum held a plenary session to establish a multinational consensus on the challenges faced in diabetes management within lower-middle-income countries (LMICs) and their potential solutions. Stakeholders, including patients, family/caretakers, healthcare professionals, and healthcare policymakers & organizations, participated in discussions. The audience of 280 doctors from 15 different countries (Pakistan, Qatar, Sri Lanka, Kenya, Myanmar, Georgia, Nigeria, Philippines, Uzbekistan, Iraq, Tanzania, Cambodia, Kazakhstan, South Sudan and Libya) was divided into 4 groups led by Group Leaders to represent each stakeholder group. Questionnaires addressing key challenges and solutions specific to each group were used to facilitate consensus development. Participants voted on relevant options based on their clinical experience. SLIDO software was used for polling, generating separate results for each group. The insights shared by healthcare professionals highlighted the importance of improving medication accessibility and cost-effectiveness for patients, emphasizing the need for adherence to treatment plans and lifestyle modifications. The significance of balanced nutrition with low glycemic index food for enhancing quality of life was recognized. Caregivers of diabetic patients with comorbidities face increasing demands for care, particularly in relation to age-related milestones. Healthcare professionals emphasized the challenges posed by cultural beliefs and health awareness, underscoring the importance of teamwork and early referral for managing comorbidities. Healthcare policymakers need to focus on disease education, awareness programs, screening guidelines, and advocacy for community and clinical screening. By addressing these challenges, a more comprehensive and effective approach to diabetes management can be achieved in LMICs, ultimately improving outcomes for individuals with diabetes.

Diabetes in a hospital cohort of persons living with HIV: a descriptive and comparative study in French Guiana

BACKGROUND

In French Guiana (population 294,000) the prevalence of type 2 diabetes (10%) and of HIV(1.1%) are very high. Our objective was to determine the prevalence of diabetes and its complications in a HIV cohort.

MATERIALS AND METHODS

We enrolled HIV-infected persons followed in Cayenne, Kourou, and Saint Laurent du Maroni hospitals between January 1, 1992 and December 31, 2021 in the French Hospital Database for HIV (FHDH) a national database compiling data from all French regions.

RESULTS

There was no difference of diabetes prevalence between men (8.2%) and women (8.8%), P = 0.4. Patients with diabetes were older (56 years ± 13.4) than those without diabetes (44.7 years ± 13.6) and prevalence increased with age. The proportion of persons with diabetes was greater among virologically suppressed persons (10%) than those with a detectable viral load under antiretroviral treatment (5.8%). Persons with diabetes had substantially greater CD4 counts at diagnosis than persons without diabetes. The majority of macro and microvascular complications were observed in people with diabetes. Persons with diabetes and HIV were significantly less likely to have had AIDS (1.6 versus 2.2 per 100 person-years, respectively). Overall, 374 persons living with HIV of 4167 had died (9%) the proportion of persons with diabetes among the dead was greater than those who did not die 11.7% versus 8.1%, respectively, p = 0.017. However, persons with diabetes were older and hence died older, 62.3 years (SD = 1.9) for deceased persons with diabetes versus 50.4 years (SD = 0.8), P < 0.0001. However, using Cox regression to adjust for age, initial CD4 count, country of birth there was no significant difference in the Hazard for death between persons with diabetes and persons without diabetes (aHR = 0.99, 95%CI = 0.65-1.5), P = 0.9.

CONCLUSIONS

The prevalence of diabetes in our HIV cohort was high. Persons with diabetes had greater CD4 counts, earlier care, and greater virological suppression than persons without diabetes. There were no significant differences between persons with diabetes and without diabetes in terms of survival.

Evidence of impaired H-reflex and H-reflex rate-dependent depression in diabetes, prediabetes and obesity: a mini-review

Diabetes Mellitus is a public health problem associated with complications such as neuropathy; however, it has been proposed that these may begin to develop during prediabetes and may also be present in persons with obesity. Diabetic peripheral neuropathy is the presence of signs and/or symptoms of peripheral nerve dysfunction in people living with diabetes, which increases the risk of developing complications and has a deleterious impact on quality of life. As part of the therapeutic protocol for diabetes, screening tests to identify peripheral neuropathy are suggested, however, there are no recommendations for people with prediabetes and obesity without symptoms such as pain, numbness, or paresthesias. Moreover, clinical screening tests that are usually used to recognize this alteration, such as tendon reflex, temperature sensation, and pressure and vibration perception, might be subjective as they depend on the evaluator's experience thus the incorrect application of these tests may not recognize the damage to small or large-nerve fibers. Recent evidence suggests that an objective study such as the impairment of the rate-dependent depression of the H-reflex could be used as a biomarker of spinal disinhibition and hence may provide more information on sensorimotor integration.

Painful Diabetic Peripheral Neuropathy: Practical Guidance and Challenges for Clinical Management

Painful diabetic peripheral neuropathy (PDPN) is present in nearly a quarter of people with diabetes. It is estimated to affect over 100 million people worldwide. PDPN is associated with impaired daily functioning, depression, sleep disturbance, financial instability, and a decreased quality of life. Despite its high prevalence and significant health burden, it remains an underdiagnosed and undertreated condition. PDPN is a complex pain phenomenon with the experience of pain associated with and exacerbated by poor sleep and low mood. A holistic approach to patient-centred care alongside the pharmacological therapy is required to maximise benefit. A key treatment challenge is managing patient expectation, as a good outcome from treatment is defined as a reduction in pain of 30-50%, with a complete pain-free outcome being rare. The future for the treatment of PDPN holds promise, despite a 20-year void in the licensing of new analgesic agents for neuropathic pain. There are over 50 new molecular entities reaching clinical development and several demonstrating benefit in early-stage clinical trials. We review the current approaches to its diagnosis, the tools, and questionnaires available to clinicians, international guidance on PDPN management, and existing pharmacological and non-pharmacological treatment options. We synthesise evidence and the guidance from the American Association of Clinical Endocrinology, American Academy of Neurology, American Diabetes Association, Diabetes Canada, German Diabetes Association, and the International Diabetes Federation into a practical guide to the treatment of PDPN and highlight the need for future research into mechanistic-based treatments in order to prioritise the development of personalised medicine.

Spinal disinhibition: evidence for a hyperpathia phenotype in painful diabetic neuropathy

The dominant sensory phenotype in patients with diabetic polyneuropathy and neuropathic pain is a loss of function. This raises questions as to which mechanisms underlie pain generation in the face of potentially reduced afferent input. One potential mechanism is spinal disinhibition, whereby a loss of spinal inhibition leads to increased ascending nociceptive drive due to amplification of, or a failure to suppress, incoming signals from the periphery. We aimed to explore whether a putative biomarker of spinal disinhibition, impaired rate-dependent depression of the Hoffmann reflex, is associated with a mechanistically appropriate and distinct pain phenotype in patients with painful diabetic neuropathy. In this cross-sectional study, 93 patients with diabetic neuropathy underwent testing of Hoffmann reflex rate-dependent depression and detailed clinical and sensory phenotyping, including quantitative sensory testing. Compared to neuropathic patients without pain, patients with painful diabetic neuropathy had impaired Hoffmann reflex rate-dependent depression at 1, 2 and 3 Hz (P ≤ 0.001). Patients with painful diabetic neuropathy exhibited an overall loss of function profile on quantitative sensory testing. However, within the painful diabetic neuropathy group, cluster analysis showed evidence of greater spinal disinhibition associated with greater mechanical pain sensitivity, relative heat hyperalgesia and higher ratings of spontaneous burning pain. These findings support spinal disinhibition as an important centrally mediated pain amplification mechanism in painful diabetic neuropathy. Furthermore, our analysis indicates an association between spinal disinhibition and a distinct phenotype, arguably akin to hyperpathia, with combined loss and relative gain of function leading to increasing nociceptive drive.

Impaired rate-dependent depression of the H-reflex in type-2 diabetes, prediabetes, overweight and obesity: A cross-sectional study

Type-2 diabetes is a chronic metabolic disorder characterized by hyperglycemia, resulting from deficits in insulin secretion or insulin resistance. According to the International Diabetes Federation, approximately 463 million people suffered from this condition in 2019, with a rapidly increasing impact in low-and middle-income countries. Obesity is a well-known risk factor for diabetes, and current data project a continuous increase in diabetes prevalence worldwide in obese individuals. Among the common complications, diabetic peripheral neuropathy (DPN) causes sensory symptoms, including pain that contributes to foot ulceration, and if not controlled, limb amputation may occur. The diagnosis of DPN is a clinical problem. Rate-dependent depression (RDD) of the Hoffmann reflex in the lower limbs has been proposed as a test to determine the presence of neuropathic pain in subjects with type-1 and type-2 diabetes. Recently, impaired RDD has been described in obese and diabetic rodent models. In this study, we characterized the RDD by evaluating the H-reflex at 0.2, 1, 2, 5, and 10 Hz in 39 patients with type-2 Diabetes mellitus (T2DM) and 42 controls without diabetes, subsequently classified as overweight/obese and prediabetic. A significant decrease in the RDD of the H-reflex was found in T2DM subjects at 1, 2, 5, and 10 Hz (P < .001) stimulation frequencies compared to controls, but not at 0.2 Hz (P = .48). A major finding of this study is that impaired RDD was also found in 11/25 overweight and obese subjects in at least 2 stimulation frequencies, being 10 of those classified in prediabetic levels according to their HbA1C values. The RDD of the H-reflex could be used as a quantitative and sensitive tool to study T2DM subpopulations with peripheral neuropathy. RDD could be used as a screening tool in combination with clinical tests to diagnose DPN and evaluate the progression of this condition.

Recent updates in the treatment of diabetic polyneuropathy

Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.

Effects of Neural Mobilization on Sensory Dysfunction and Peripheral Nerve Degeneration in Rats With Painful Diabetic Neuropathy

OBJECTIVE

This study aims to evaluate the effectiveness of neural mobilization (NM) in the management of sensory dysfunction and nerve degeneration related to experimental painful diabetic neuropathy (PDN).

METHODS

This is a pre-clinical animal study performed in the streptozocin-induced diabetic rat model. Three groups were included: a treatment group of rats with PDN receiving NM under anesthesia (PDN-NM, n = 10), a sham treatment group of rats with PDN that received only anesthesia (PDN-Sham, n = 9), and a vehicle control group with nondiabetic animals (Vehicle, n = 10). Rats in the PDN-NM and PDN-Sham groups received 1 treatment session on days 10, 12, and 14 after streptozocin injection, with a 48-hour rest period between sessions. Behavioral tests were performed using von Frey and Plantar tests. Evaluation for peripheral nerve degeneration was performed through measuring protein gene product 9.5-positive intra-epidermal nerve fiber density in hind-paw skin biopsies. All measurements were performed by a blinded investigator.

RESULTS

The behavioral tests showed that a single NM session could reduce hyperalgesia, which was maintained for 48 hours. The second treatment session further improved this treatment effect, and the third session maintained it. These results suggest that it requires multiple treatment sessions to produce and maintain hypoalgesic effects. Skin biopsy analysis showed that the protein gene product 9.5-positive intra-epidermal nerve fiber density was higher on the experimental side of the PDN-NM group compared with the PDN-Sham group, suggesting NM may mitigate the degeneration of peripheral nerves.

CONCLUSION

This study demonstrated that NM may be an effective method to manage experimentally induced PDN, potentially through mitigation of nerve degeneration. Further studies are needed to develop standardized protocols for clinical use.

IMPACT

These findings provide neurophysiological evidence for the use of NM in PDN and can form the basis for the development of physical therapy-based programs in clinics.

Rate-Dependent Depression: A Predictor of the Therapeutic Efficacy in Treating Painful Diabetic Peripheral Neuropathy

We investigated the application of rate-dependent depression (RDD) of the Hoffmann (H) wave as a predictor of treatment efficacy in patients with painful diabetic peripheral neuropathy (DPN). General medical information, scales, and nerve conduction data were collected from 73 healthy subjects, 50 subjects with type 2 diabetes and painless DPN, and 71 subjects with type 2 diabetes and painful DPN. The left tibial nerve was stimulated, and RDD was calculated by the decline in amplitude of the third H wave relative to the first one. Gabapentin treatment was initiated after baseline evaluation, and the RDD and visual analog scale (VAS) score were both evaluated regularly during the 2-week study period. At baseline, the painful DPN group exhibited significant RDD impairment across all stimulation frequencies. Gabapentin treatment significantly reduced the VAS score and restored RDD during the 2-week observation period. RDD was found to be an independent factor of minimal VAS score improvement, such that the benefit increased by 1.27 times per 1% decrease in the RDD value. In conclusion, this study demonstrates that diabetes-induced loss of RDD can be modified by gabapentin and suggests that RDD may be valuable for predicting the initial efficacy of gabapentin therapy in patients with painful DPN.

Recent updates in the treatment of diabetic polyneuropathy

Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.

Metformin attenuates diabetic neuropathic pain via AMPK/NF-κB signaling pathway in dorsal root ganglion of diabetic rats

Neuropathic pain is a common complication of diabetes mellitus with poorly relieved by conventional analgesics. Metformin, a first-line drug for type 2 diabetes, reduces blood glucose by activating adenosine monophosphate protein kinase (AMPK) signalling system. However, the effect of Metformin on diabetic neuropathic pain is still unknown. In the present study, we showed that Metformin was capable of attenuating diabetes induced mechanical allodynia, and the analgesia effect could be blocked by Compound C (an AMPK inhibitor). Importantly, Metformin enhanced the phosphorylation level of AMPK in L4-6 DRGs of diabetic rats but not affect the expression of total AMPK. Intrathecal injection of AICAR (an AMPK agonist) could activate AMPK and alleviate the mechanical allodynia of diabetic rats. Additionally, phosphorylated AMPK and NF-κB was co-localized in small and medium neurons of L4-6 DRGs. Interestingly, the regulation of NF-κB in diabetic rats was obviously reduced when AMPK was activated by AICAR. Notably, Metformin could decrease NF-κB expression in L4-6 DRGs of diabetic rats, but the decrease was blocked by Compound C. In conclusion, Metformin alleviates diabetic mechanical allodynia via activation of AMPK signaling pathway in L4-6 DRGs of diabetic rats, which might be mediated by the downregulation of NF-κB, and this providing certain basis for Metformin to become a potential drug in the clinical treatment of diabetic neuropathic pain.

Systematic Review of Systemic and Neuraxial Effects of Acetaminophen in Preclinical Models of Nociceptive Processing

Acetaminophen (APAP) in humans has robust effects with a high therapeutic index in altering postoperative and inflammatory pain states in clinical and experimental pain paradigms with no known abuse potential. This review considers the literature reflecting the preclinical actions of acetaminophen in a variety of pain models. Significant observations arising from this review are as follows: 1) acetaminophen has little effect upon acute nociceptive thresholds; 2) acetaminophen robustly reduces facilitated states as generated by mechanical and thermal hyperalgesic end points in mouse and rat models of carrageenan and complete Freund’s adjuvant evoked inflammation; 3) an antihyperalgesic effect is observed in models of facilitated processing with minimal inflammation (eg, phase II intraplantar formalin); and 4) potent anti-hyperpathic effects on the thermal hyperalgesia, mechanical and cold allodynia, allodynic thresholds in rat and mouse models of polyneuropathy and mononeuropathies and bone cancer pain. These results reflect a surprisingly robust drug effect upon a variety of facilitated states that clearly translate into a wide range of efficacy in preclinical models and to important end points in human therapy. The specific systems upon which acetaminophen may act based on targeted delivery suggest both a spinal and a supraspinal action. Review of current targets for this molecule excludes a role of cyclooxygenase inhibitor but includes effects that may be mediated through metabolites acting on the TRPV1 channel, or by effect upon cannabinoid and serotonin signaling. These findings suggest that the mode of action of acetaminophen, a drug with a long therapeutic history of utilization, has surprisingly robust effects on a variety of pain states in clinical patients and in preclinical models with a good therapeutic index, but in spite of its extensive use, its mechanisms of action are yet poorly understood.

Rate-dependent depression is impaired in amyotrophic lateral sclerosis

OBJECTIVE

We investigated rate-dependent depression (RDD) of the Hoffman reflex (H-reflex) in patients with amyotrophic lateral sclerosis (ALS), a degenerative disease with ventral horn involvement.

PATIENTS AND METHODS

In this case-control study, we enrolled 27 patients with ALS and 30 matched healthy control subjects. Clinical and electrophysiological assessments, as well as RDD in response to various stimulation frequencies (0.5 Hz, 1 Hz, 3 Hz and 5 Hz), were compared between groups. Multiple clinical and electrophysiological factors were also explored to determine any underlying associations with RDD.

RESULTS

The ALS group showed a significant loss of RDD across all frequencies compared to the control group, most notably following 1 Hz stimulation (19.1 ± 20.3 vs. 34.0 ± 13.7%, p = 0.003). Among factors that might influence RDD, the enlargement of the motor unit potential (MUP) showed a significant relationship with RDD following multifactor analysis of variance (p = 0.007) and Pearson correlation analysis (ρ =  - 0.70, p < 0.001), while various upper motor neuron manifestations were not correlated with RDD values (p > 0.05).

CONCLUSION

We report a loss of RDD in patients with ALS. The strong correlation detected between the RDD deficit and increased MUP suggests that RDD is a sensitive indicator of underlying spinal disinhibition in ALS.

TRIAL REGISTRATION

ChiCTR2000038848, 10/7/2020 (retrospectively registered), http://www.chictr.org.cn/ .

Spinal Inhibitory Dysfunction in Patients With Painful or Painless Diabetic Neuropathy

OBJECTIVE

Impaired rate-dependent depression of the Hoffman reflex (HRDD) is a marker of spinal inhibitory dysfunction and has previously been associated with painful neuropathy in a proof-of-concept study in patients with type 1 diabetes. We have now undertaken an assessment of HRDD in patients with type 1 or type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 148 participants, including 34 healthy control subjects, 42 patients with painful diabetic neuropathy, and 62 patients with diabetic neuropathy without pain, underwent an assessment of HRDD and a detailed assessment of peripheral neuropathy, including nerve conduction studies, corneal confocal microscopy, and thermal threshold testing.

RESULTS

Compared with healthy control subjects (P < 0.001) and patients without pain (P < 0.001), we found that HRDD is impaired in patients with type 1 or type 2 diabetes with neuropathic pain. These impairments are unrelated to diabetes type and the presence or severity of neuropathy. In contrast, patients without neuropathic pain (P < 0.05) exhibited enhanced HRDD compared with control subjects.

CONCLUSIONS

We suggest that loss or impairment of HRDD may help to identify a subpopulation of patients with painful diabetic neuropathy mediated by impaired spinal inhibitory systems who may respond optimally to therapies that target spinal or supraspinal mechanisms. Enhanced RDD in patients without pain may reflect engagement of spinal pain-suppressing mechanisms.

Novel and Emerging Electrophysiological Biomarkers of Diabetic Neuropathy and Painful Diabetic Neuropathy

PURPOSE

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes. Small and large peripheral nerve fibers can be involved in DPN. Large nerve fiber damage causes paresthesia, sensory loss, and muscle weakness, and small nerve fiber damage is associated with pain, anesthesia, foot ulcer, and autonomic symptoms. Treatments for DPN and painful DPN (pDPN) pose considerable challenges due to the lack of effective therapies. To meet these challenges, there is a major need to develop biomarkers that can reliably diagnose and monitor progression of nerve damage and, for pDPN, facilitate personalized treatment based on underlying pain mechanisms.

METHODS

This study involved a comprehensive literature review, incorporating article searches in electronic databases (Google Scholar, PubMed, and OVID) and reference lists of relevant articles with the authors' substantial expertise in DPN. This review considered seminal and novel research and summarizes emerging biomarkers of DPN and pDPN that are based on neurophysiological methods.

FINDINGS

From the evidence gathered from 145 papers, this submission describes emerging clinical neurophysiological methods with potential to act as biomarkers for the diagnosis and monitoring of DPN as well as putative future roles as predictors of response to antineuropathic pain medication in pDPN. Nerve conduction studies only detect large fiber damage and do not capture pathology or dysfunction of small fibers. Because small nerve fiber damage is prominent in DPN, additional biomarkers of small nerve fiber function are needed. Activation of peripheral nociceptor fibers using laser, heat, or targeted electrical stimuli can generate pain-related evoked potentials, which are an objective neurophysiological measure of damage along the small fiber pathways. Assessment of nerve excitability, which provides a surrogate of axonal properties, may detect alterations in function before abnormalities are detected by nerve conduction studies. Microneurography and rate-dependent depression of the Hoffmann-reflex can be used to dissect underlying pain-generating mechanisms arising from the periphery and spinal cord, respectively. Their role in informing mechanistic-based treatment of pDPN as well as facilitating clinical trials design is discussed.

IMPLICATIONS

The neurophysiological methods discussed, although currently not practical for use in busy outpatient settings, detect small fiber and early large fiber damage in DPN as well as disclosing dominant pain mechanisms in pDPN. They are suited as diagnostic and predictive biomarkers as well as end points in mechanistic clinical trials of DPN and pDPN.

Diabetic neuropathy and neuropathic pain: a (con)fusion of pathogenic mechanisms?

Neuropathy is a common complication of long-term diabetes that impairs quality of life by producing pain, sensory loss and limb amputation. The presence of neuropathy in both insulin-deficient (type 1) and insulin resistant (type 2) diabetes along with the slowing of progression of neuropathy by improved glycemic control in type 1 diabetes has caused the majority of preclinical and clinical investigations to focus on hyperglycemia as the initiating pathogenic lesion. Studies in animal models of diabetes have identified multiple plausible mechanisms of glucotoxicity to the nervous system including post-translational modification of proteins by glucose and increased glucose metabolism by aldose reductase, glycolysis and other catabolic pathways. However, it is becoming increasingly apparent that factors not necessarily downstream of hyperglycemia can also contribute to the incidence, progression and severity of neuropathy and neuropathic pain. For example, peripheral nerve contains insulin receptors that transduce the neurotrophic and neurosupportive properties of insulin, independent of systemic glucose regulation, while the detection of neuropathy and neuropathic pain in patients with metabolic syndrome and failure of improved glycemic control to protect against neuropathy in cohorts of type 2 diabetic patients has placed a focus on the pathogenic role of dyslipidemia. This review provides an overview of current understanding of potential initiating lesions for diabetic neuropathy and the multiple downstream mechanisms identified in cell and animal models of diabetes that may contribute to the pathogenesis of diabetic neuropathy and neuropathic pain.

Altered Spinal Excitability in Patients with Primary Fibromyalgia: A Case-Control Study

Background and Purpose

Abnormal excitability of the central nervous system, both spinal and supraspinal, has previously been described as a pathophysiological plastic mechanism for chronic pain syndromes. Primary fibromyalgia (FM) as one extreme of this spectrum of diseases. This case-control study aimed to determine the changes in the spinal excitability by investigating the Hoffman reflex (H-reflex) in patients with FM.

Methods

Thirty-eight patients with FM and 30 healthy controls participated in this case-control study. We measured the H-reflex bilaterally in the upper limbs (flexor carpi radialis) and the lower limbs (gastrocnemius and soleus). Moreover, pain-related variables were measured, including pain severity (using a visual analogue scale), pain duration, Widespread Pain Index, and the score on the Symptom Severity Scale. Various psychiatric comorbidities and quality-of-life parameters were measured for each patient, including scores on the Hamilton Depression Rating Scale, Taylor's Manifest Anxiety Scale, and the Revised Fibromyalgia Impact Questionnaire.

Results

A significant increase in the ratio of the maximum baseline-to-peak amplitudes of H and M waves (H_max/M_max) but not in the H-wave minimum latency was found in patients with FM compared with healthy controls. There were no significant correlations between this ratio in both muscles and the various pain-related measures, psychiatric comorbidity, and quality of life in patients with FM. Patients with FM suffered more depression and anxiety than did the controls.

Conclusions

We found increased spinal excitability in patients with FM, which was not confined to the site of maximum pain. This information may help in the diagnosis of FM and supports the hypothesis of central sensitization.

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.

Diabetes Mellitus and Associated Factors Among Adult HIV Patients on Highly Active Anti-Retroviral Treatment

BACKGROUND

Highly active anti-retroviral therapy (HAART) prolongs the life span of people living with HIV (PLWHIV) and intensely reduces HIV-related morbidity and mortality. Globally, HIV-associated non-communicable diseases are becoming major public concerns, and chronic comorbidities have appeared as a substantial reason for morbidity and mortality in HIV patients with prolonged use of HAART.

PURPOSE

A cross-sectional study design was used to assess the magnitude of diabetes mellitus and risk factors among adult HIV patients exposed to HAART at Jimma Zone Public Hospitals from May to July 30, 2018.

PATIENTS AND METHODS

A convenient sampling technique was used to include a total of 271 adult HIV patients on HAART visiting the selected health facilities at the time of data collection. Socio-demographic and clinical data were collected by interviewer-administered questionnaire and by reviewing patients' record data. Bivariate and multivariate logistic regressions were used to identify variables that are independent predictors for diabetes mellitus.

RESULTS

The prevalence of diabetes and pre-diabetes among PLWHIV exposed to HAART was 11.4% and 16.6%, respectively. The prevalence of diabetic dyslipidemia in PLWHIV exposed on HAART was 8.9% (n=24). Government workers (AOR: 0.17, 95% C.I=0.03-0.85, P=0.031), long duration in HAART use (AOR: 11.06, 95% C.I:1.03-18.67, P=0.047), hyper-triglyceridemia (AOR: 2.62,95% C.I:0.82, 8.39, P=0.005), LDL-C <130 mg/dl (AOR: 4.04, 95% C.I=1.33-12.30, P=0.014), and obesity (AOR: 9.62, 95% C.I: 1.01-91.52, P=0.049) were independent risk factors for diabetes mellitus in PLWHIV exposed to HAART.

CONCLUSION

Exposure to HAART increased the prevalence of diabetes mellitus in PLWHIV although it enhances quality of life, improves immune functions and prevents the onset of opportunistic infections. Therefore, regular screening for blood glucose level for PLWHIV on HAART is advisable.

State-of-the-art pharmacotherapy for diabetic neuropathy

INTRODUCTION

The global epidemic of diabetes has led to an epidemic of diabetes complications. Diabetic neuropathy is the most common microvascular complication, of which diabetic peripheral neuropathy (DPN) and autonomic neuropathy (AN) are the most prevalent, affecting ~50% of patients. DPN results in pain with a poor quality of life and a loss of sensation with an increased risk of foot ulceration. Autonomic neuropathy can cause significant morbidity in a minority and is associated with increased mortality. The cornerstone of treatment to prevent or limit the progression of DPN/AN is multifactorial risk factor modification including treatment of glycemia, lipids and blood pressure. Whilst, there are no FDA-approved disease-modifying therapies, there are a number of therapies to relieve symptoms in DPN and AN.

AREAS COVERED

The authors discuss current approved therapies for painful diabetic neuropathy and autonomic neuropathy. They also address the potential role of improving risk factors to limit the development and progression of diabetic neuropathy and new pathogenetic and pain-relieving treatments.

EXPERT OPINION

The FDA-approved Pregabalin and Duloxetine over 25 years ago and Tapentadol, 6 years ago for painful diabetic neuropathy. There are currently no FDA-approved disease-modifying treatments for diabetic neuropathy which has been attributed to inappropriate models of the disease with limited translational capacity and major limitations of trial designs and endpoints in clinical trials.

Tumour travel tours - Why circulating cancer cells value company

Welcome to the New Year and a new issue of the Biomedical Journal, where we learn that travelling with company boosts the metastatic potential of circulating tumour cells, as well as that a worm could be an excellent model to study antidiabetic drugs. In addition, we discover another pair of molecular scissors for genetic engineering, how exactly Leptospira wreaks havoc on its run through the host organism, and that hyperparathyroidism brings its own risks, but does not worsen the outcome of papillary thyroid carcinoma. Furthermore, the importance of taking into account differing beauty ideals for aesthetic surgery surveys is discussed, alongside the question how bad isolated local recurrence is in the case of HR + breast cancer. Finally, we find out that virtual colonoscopy deserves more credit, that the first medical experiment in space was all about the H-reflex, and that it is possible to survive advanced necrotising fasciitis of the face and neck.

Spinal cord motor neuron plasticity accompanies second-degree burn injury and chronic pain

Burn injuries and associated complications present a major public health challenge. Many burn patients develop clinically intractable complications, including pain and other sensory disorders. Recent evidence has shown that dendritic spine neuropathology in spinal cord sensory and motor neurons accompanies central nervous system (CNS) or peripheral nervous system (PNS) trauma and disease. However, no research has investigated similar dendritic spine neuropathologies following a cutaneous thermal burn injury. In this retrospective investigation, we analyzed dendritic spine morphology and localization in alpha-motor neurons innervating a burn-injured area of the body (hind paw). To identify a molecular regulator of these dendritic spine changes, we further profiled motor neuron dendritic spines in adult mice treated with romidepsin, a clinically approved Pak1-inhibitor, or vehicle control at two postburn time points: Day 6 immediately after treatment, or Day 10 following drug withdrawal. In control treated mice, we observed an overall increase in dendritic spine density, including structurally mature spines with mushroom-shaped morphology. Pak1-inhibitor treatment reduced injury-induced changes to similar levels observed in animals without burn injury. The effectiveness of the Pak1-inhibitor was durable, since normalized dendritic spine profiles remained as long as 4 days despite drug withdrawal. This study is the first report of evidence demonstrating that a second-degree burn injury significantly affects motor neuron structure within the spinal cord. Furthermore, our results support the opportunity to study dendritic spine dysgenesis as a novel avenue to clarify the complexities of neurological disease following traumatic injury.

Difficulties in emotion regulation and deficits in interoceptive awareness in moderate and severe obesity

PURPOSE

Difficulties in emotion regulation and deficits in interoceptive awareness may be responsible for overeating and weight gain in obesity by increasing the risks of problematic eating behaviors. This study aimed to: (1) examine emotion regulation difficulties and interoceptive deficits in obesity; (2) compare the emotion regulation and interoceptive abilities of moderately and severely obese patients.

METHODS

Participants were recruited through the university, diabetology centers and bariatric surgery departments. A total of 165 participants were categorized in three groups, matched by age and gender, according to their Body Mass Index (BMI). The severely obese (SO), moderately obese (MO) and normal weight (NW) groups were constituted of 55 participants each. Self-report questionnaires were used to assess emotion regulation difficulties (CERQ-DERS) and interoceptive awareness (MAIA-FFMQ).

RESULTS

Overall, obese participants reported more emotion regulation difficulties and less interoceptive awareness than NW participants did. They also reported a lack of planning strategies and emotional awareness, as well as less ability to observe, notice and trust body sensations. No differences in emotion regulation and interoceptive abilities were found between MO and SO participants.

CONCLUSIONS

Emotion regulation and interoceptive awareness should be targeted in the psychotherapeutic care of obese people, regardless of their BMI.

LEVEL OF EVIDENCE

Level III, case-control analytic study.

Relationships among Child Eating Behaviors and Household Food Insecurity in Youth with Obesity

Background: Food insecurity may trigger eating behaviors that contribute to pediatric obesity. The aim of this study is to identify eating behaviors among a pediatric population with obesity and household food insecurity. Methods: A cross-sectional study analyzed Child Eating Behavior Questionnaire (CEBQ) and household food insecurity screener responses, and BMI measurements from pediatric participants with obesity (BMI ≥95th percentile) from a weight management clinic between 2013 and 2017. Multivariate linear regression was performed to evaluate associations between CEBQ eating domains [Food Responsiveness, Emotional Overeating, Enjoyment of Food, Desire to Drink (DD), Satiety Responsiveness, Slowness in Eating, Emotional Undereating (EUE), and Food Fussiness] and household food insecurity, adjusting for age, sex, race/ethnicity, SNAP participation, and BMI percentile. A sub-group analysis was performed on participants from food insecure (FI) households to evaluate the associations between SNAP participation and eating domains. Results: Eight hundred twenty-two participants were included in the final analysis. Participants from FI households had significantly higher BMI percentiles even after adjustment for age, sex, race/ethnicity, and SNAP status (p = 0.000). Household food insecurity was associated with increased DD beverages (p = 0.000). Among participants from FI households, SNAP participation was significantly positively associated with the EUE (p = 0.009). Conclusions: Youth from FI households have higher BMIs even among a population with obesity. DD is positively associated with household food insecurity and may contribute to obesity in this population. Results suggest that providers treating pediatric patients with obesity should consider regularly screening for household food insecurity and associated eating behaviors as part of their medical management of obesity.

Disorganized attachment predicts body mass index via uncontrolled eating

BACKGROUND/OBJECTIVES

Previous research has demonstrated relationships between attachment orientations (expectations of ourselves and others in interpersonal relationships), eating behaviours and obesity. However, such research has been limited to investigations of 'organised' forms of attachment orientations (reflecting coherent and predictable patterns of behaviour). Theoretically, aberrant eating behaviours and body mass index, should also be related to 'disorganized attachment.'

SUBJECTS

Here we test these relationships for the first time in a general population. Secondary data analyses of a pre-existing dataset were conducted (N = 537).

METHODS USED

Questionnaire measures of organised (avoidant and anxious) and disorganized attachment were included alongside eating behaviour measures (emotional eating, uncontrolled eating and cognitive restraint) and body mass index (BMI).

RESULTS

Parallel multiple mediation analysis (PROCESS) showed that uncontrolled eating (but not emotional eating or cognitive restraint) significantly mediated a relationship between disorganized attachment and body mass index (significant indirect relationship; LLCI = 0.02 ULCI = 0.16) when both attachment anxiety and avoidance were included as covariates.

CONCLUSIONS

We suggest that the mechanism underpinning this indirect relationship is a form of maladaptive affect regulation, but that the behavioural motivators differ from those observed in anxiously attached individuals. Rather than eating being a premeditated strategy used by individuals high in disorganized attachment to manage emotion, opportunities to eat are simply taken as they present themselves. Professionals engaged in addressing eating problems and weight management should consider attachment orientations in their patient assessments and be mindful that attachment disorganized individuals are especially likely to engage in uncontrolled eating behaviours that are associated with a higher BMI.

Painful and Painless Diabetic Neuropathies: What Is the Difference?

PURPOSE OF REVIEW

The prevalence of diabetes mellitus and its chronic complications are increasing to epidemic proportions. This will unfortunately result in massive increases in diabetic distal symmetrical polyneuropathy (DPN) and its troublesome sequelae, including disabling neuropathic pain (painful-DPN), which affects around 25% of patients with diabetes. Why these patients develop neuropathic pain, while others with a similar degree of neuropathy do not, is not clearly understood. This review will look at recent advances that may shed some light on the differences between painful and painless-DPN.

RECENT FINDINGS

Gender, clinical pain phenotyping, serum biomarkers, brain imaging, genetics, and skin biopsy findings have been reported to differentiate painful- from painless-DPN. Painful-DPN seems to be associated with female gender and small fiber dysfunction. Moreover, recent brain imaging studies have found neuropathic pain signatures within the central nervous system; however, whether this is the cause or effect of the pain is yet to be determined. Further research is urgently required to develop our understanding of the pathogenesis of pain in DPN in order to develop new and effective mechanistic treatments for painful-DPN.

Mirogabalin and emerging therapies for diabetic neuropathy

There are currently no approved disease-modifying therapies for diabetic neuropathy, and there are only 3 US Food and Drug Administration-approved therapies (pregabalin, duloxetine, and tapentadol) for painful diabetic neuropathy. They each have moderate efficacy with adverse effects limiting optimal dose titration. There is a considerable need for new therapies for the management of painful diabetic neuropathy. We reviewed the potential role of mirogabalin, which like gabapentin and pregabalin modulates the alpha-2/delta-1 subunit of the voltage-gated calcium channel, allowing the influx of calcium and release of neurotransmitters at the synaptic cleft in the central nervous system and spinal cord. It has shown efficacy and good tolerability in a Phase II study in diabetic painful neuropathy and based on the results of two Phase III clinical trials in diabetic painful neuropathy and post-herpetic neuralgia, Daiichi Sankyo submitted a marketing application for neuropathic pain in Japan in February 2018. We have also reviewed potential new therapies, currently in Phase II clinical trials that may modify disease and/or relieve neuropathic pain through novel modes of action.

Diagnosing Diabetic Neuropathy: Something Old, Something New

There are potentially many ways of assessing diabetic peripheral neuropathy (DPN). However, they do not fulfill U.S. Food and Drug Administration (FDA) requirements in relation to their capacity to assess therapeutic benefit in clinical trials of DPN. Over the past several decades symptoms and signs, quantitative sensory and electrodiagnostic testing have been strongly endorsed, but have consistently failed as surrogate end points in clinical trials. Therefore, there is an unmet need for reliable biomarkers to capture the onset and progression and to facilitate drug discovery in DPN. Corneal confocal microscopy (CCM) is a non-invasive ophthalmic imaging modality for in vivo evaluation of sensory C-fibers. An increasing body of evidence from multiple centers worldwide suggests that CCM fulfills the FDA criteria as a surrogate endpoint of DPN.

Diabetic Peripheral Neuropathy: Epidemiology, Diagnosis, and Pharmacotherapy

PURPOSE

Diabetic peripheral neuropathy (DPN) is the commonest cause of neuropathy worldwide, and its prevalence increases with the duration of diabetes. It affects approximately half of patients with diabetes. DPN is symmetric and predominantly sensory, starting distally and gradually spreading proximally in a glove-and-stocking distribution. It causes substantial morbidity and is associated with increased mortality. The unrelenting nature of pain in this condition can negatively affect a patient's sleep, mood, and functionality and result in a poor quality of life. The purpose of this review was to critically review the current literature on the diagnosis and treatment of DPN, with a focus on the treatment of neuropathic pain in DPN.

METHODS

A comprehensive literature review was undertaken, incorporating article searches in electronic databases (EMBASE, PubMed, OVID) and reference lists of relevant articles with the authors' expertise in DPN. This review considers seminal and novel research in epidemiology; diagnosis, especially in relation to novel surrogate end points; and the treatment of neuropathic pain in DPN. We also consider potential new pharmacotherapies for painful DPN.

FINDINGS

DPN is often misdiagnosed and inadequately treated. Other than improving glycemic control, there is no licensed pathogenetic treatment for diabetic neuropathy. Management of painful DPN remains challenging due to difficulties in personalizing therapy and ascertaining the best dosing strategy, choice of initial pharmacotherapy, consideration of combination therapy, and deciding on defining treatment for poor analgesic responders. Duloxetine and pregabalin remain first-line therapy for neuropathic pain in DPN in all 5 of the major published guidelines by the American Association of Clinical Endocrinologists, American Academy of Neurology, European Federation of Neurological Societies, National Institute of Clinical Excellence (United Kingdom), and the American Diabetes Association, and their use has been approved by the US Food and Drug Administration.

IMPLICATIONS

Clinical recognition of DPN is imperative for allowing timely symptom management to reduce the morbidity associated with this condition.