Distal Symmetric Polyneuropathy: A Review

Use of Cannabis and Cannabinoids for Treatment of Cancer

The endocannabinoid system (ECS) is an ancient homeostasis mechanism operating from embryonic stages to adulthood. It controls the growth and development of many cells and cell lineages. Dysregulation of the components of the ECS may result in uncontrolled proliferation, adhesion, invasion, inhibition of apoptosis and increased vascularization, leading to the development of various malignancies. Cancer is the disease of uncontrolled cell division. In this review, we will discuss whether the changes to the ECS are a cause or a consequence of malignization and whether different tissues react differently to changes in the ECS. We will discuss the potential use of cannabinoids for treatment of cancer, focusing on primary outcome/care-tumor shrinkage and eradication, as well as secondary outcome/palliative care-improvement of life quality, including pain, appetite, sleep, and many more factors. Finally, we will complete this review with the chapter on sex- and gender-specific differences in ECS and response to cannabinoids, and equality of the access to treatments with cannabinoids.

Mechanisms of exercise for diabetic neuropathic pain

Diabetic neuropathic pain (DNP) is a common disease that affects the daily lives of diabetic patients, and its incidence rate is very high worldwide. At present, drug and exercise therapies are common treatments for DNP. Drug therapy has various side effects. In recent years, exercise therapy has received frequent research and increasing attention by many researchers. Currently, the treatment of DNP is generally symptomatic. We can better select the appropriate exercise prescription for DNP only by clarifying the exercise mechanism for its therapy. The unique pathological mechanism of DNP is still unclear and may be related to the pathological mechanism of diabetic neuropathy. In this study, the mechanisms of exercise therapy for DNP were reviewed to understand better the role of exercise therapy in treating DNP.

A Role for Fatty Acids in Peripheral Neuropathy Associated with Type 2 Diabetes and Prediabetes

Significance: As the global prevalence of diabetes rises, diabetic complications are also increasing at an alarming rate. Peripheral neuropathy (PN) is the most prevalent complication of diabetes and prediabetes, and is characterized by progressive sensory loss resulting from nerve damage. While hyperglycemia is the major risk factor for PN in type 1 diabetes (T1D), the metabolic syndrome (MetS) underlies the onset and progression of PN in type 2 diabetes (T2D) and prediabetes. Recent Advances: Recent reports show that dyslipidemia, a MetS component, is strongly associated with PN in T2D and prediabetes. Dyslipidemia is characterized by an abnormal plasma lipid profile with uncontrolled lipid levels, and both clinical and preclinical studies implicate a role for dietary fatty acids (FAs) in PN pathogenesis. Molecular studies further show that saturated and unsaturated FAs differentially regulate the nerve lipid profile and nerve function. Critical Issues: We first review the properties of FAs and the neuroanatomy of the peripheral nervous system (PNS). Second, we discuss clinical and preclinical studies that implicate the involvement of FAs in PN. Third, we summarize the potential effects of FAs on nerve function and lipid metabolism within the peripheral nerves, sensory neurons, and Schwann cells. Future Directions: Future directions will focus on identifying molecular pathways in T2D and prediabetes that are modulated by FAs in PN. Determining pathophysiological mechanisms that underlie the injurious effects of saturated FAs and beneficial properties of unsaturated FAs will provide mechanistic targets for developing new targeted therapies to treat PN associated with T2D and prediabetes. Antioxid. Redox Signal. 37, 560-577.

An overview of painful diabetic peripheral neuropathy: Diagnosis and treatment advancements

Diabetes mellitus remains a public health problem, affecting 422 million people worldwide. Currently, there is no consensus around treating painful diabetic peripheral neuropathy in a step-wise manner. Among the non-pharmacological interventions, neuromodulation has become a promising alternative. Over the past decade, significant clinical trials have paved the way for prompt inclusion of high-frequency spinal cord stimulation within the painful diabetic peripheral neuropathy treatment algorithm. This article aims to provide an updated evidence-based approach for the management of painful diabetic peripheral neuropathy.

Current profile of Charcot-Marie-Tooth disease in Africa: A systematic review

BACKGROUND AND AIMS

Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral neuropathy characterised by a high clinical and genetic heterogeneity. While most cases were described in populations with Caucasian ancestry, genetic research on CMT in Africa is scant. Only a few cases of CMT have been reported, mainly from North Africa. The current study aimed to summarise available data on CMT in Africa, with emphasis on the epidemiological, clinical, and genetic features.

METHODS

We searched PubMed, Scopus, Web of Sciences, and the African Journal Online for articles published from the database inception until April 2021 using specific keywords. A total of 398 articles were screened, and 28 fulfilled our selection criteria.

RESULTS

A total of 107 families totalling 185 patients were reported. Most studies were reported from North Africa (n = 22). The demyelinating form of CMT was the commonest subtype, and the phenotype varied greatly between families, and one family (1%) of CMT associated with hearing impairment was reported. The inheritance pattern was autosomal recessive in 91.2% (n = 97/107) of families. CMT-associated variants were reported in 11 genes: LMNA, GDAP1, GJB1, MPZ, MTMR13, MTMR2, PRX, FGD4/FRABIN, PMP22, SH3TC2, and GARS. The most common genes reported are LMNA, GDAP1, and SH3TC2 and have been found mostly in Northern African populations.

INTERPRETATION

This study reveals that CMT is not rare in Africa, and describes the current clinical and genetic profile. The review emphasised the urgent need to invest in genetic research to inform counselling, prevention, and care for CMT in numerous settings on the continent.

Matrix Metalloproteinase-2 (MMP-2) and-9 (MMP-9) Gene Variants and Microvascular Complications in Type 2 Diabetes Patients

Vascular complications are the leading cause of increased morbidity and mortality of diabetic patients. It has been postulated that matrix metalloproteinases MMP-2 and MMP-9, zinc-dependent endopeptidases through remodeling of the extracellular matrix, can contribute to the onset and progression of diabetic vascular complications. The aim of our study was to assess whether there is a major difference in single nucleotide polymorphisms in the MMP-2 (at position -1306C˃T) and MMP-9 (at position -1562C˃T) gene in type 2 diabetic patients and healthy controls and to determine whether there is an association of these gene variants with the presence of microvascular complications in diabetic patients. Our study included 102 type 2 diabetes patients and a control group which was comprised of 56 healthy controls. All diabetic patients were screened for microvascular diabetes complications. Genotypes were detected by polymerase chain reactions followed by restriction analyses with specific endonucleases and their frequencies were determined. The MMP-2 variant -1306C>T showed a negative correlation with type 2 diabetes (p=0.028). It was also shown that the presence of the -1306C allele increases the probability of developing type 2 diabetes. This was a 2.2 fold increase and that the -1306 T allele has a protective role in regards to type 2 diabetes. The MMP-2 variant -1306T showed a negative correlation with diabetic polyneuropathy (p=0.017), meaning that allele-1306T has a protective role in regards to diabetic polyneuropathy while the presence of allele -1306C increases the probability of developing diabetic polyneuropathy by 3.4 fold. Our study showed that the MMP-2 gene variant (-1306C) doubles the risk of developing type 2 diabetes, and for the first time an association of this gene variant and the presence of diabetic polyneuropathy was shown.

Foretinib mitigates cutaneous nerve fiber loss in experimental diabetic neuropathy

Diabetes is by far, the most common cause of neuropathy, inducing neurodegeneration of terminal sensory nerve fibers associated with loss of sensation, paresthesia, and persistent pain. Foretinib prevents die-back degeneration in cultured sensory and sympathetic neurons by rescuing mitochondrial activity and has been proven safe in prospective clinical trials. Here we aimed at investigating a potential neuroprotective effect of Foretinib in experimental diabetic neuropathy. A mouse model of streptozotocin induced diabetes was used that expresses yellow fluorescent protein (YFP) in peripheral nerve fibers under the thy-1 promoter. Streptozotocin-injected mice developed a stable diabetic state (blood glucose > 270 mg/dl), with a significant reduction of intraepidermal nerve fiber density by 25% at 5 weeks compared to the non-diabetic controls. When diabetic mice were treated with Foretinib, a significantly greater volume of the cutaneous nerve fibers (67.3%) in the plantar skin was preserved compared to vehicle treated (37.8%) and non-treated (44.9%) diabetic mice while proximal nerve fiber morphology was not affected. Our results indicate a neuroprotective effect of Foretinib on cutaneous nerve fibers in experimental diabetic neuropathy. As Foretinib treated mice showed greater weight loss compared to vehicle treated controls, future studies may define more sustainable treatment regimen and thereby may allow patients to take advantage of this neuroprotective drug in chronic neurodegenerative diseases like diabetic neuropathy.

Prevalence and determinants of pain in chronic inflammatory demyelinating polyneuropathy: results from the German INHIBIT registry

INTRODUCTION

Pain, fatigue and depression in chronic inflammatory demyelinating polyneuropathy (CIDP) are often underestimated, as the focus lies on sensorimotor dysfunction and gait instability. The aim of this study was to investigate their prevalence, characteristics and contribution to disability in a prospective cohort of 84 patients with CIDP.

METHODS

Pain, fatigue, depression and quality of life were measured using Pain Detect Questionnaire, Krupp's Fatigue Severity Scale, Beck Depression Inventory-II and German Short-Form-36 Health Survey. Sensorimotor deficits and disability were assessed using the Inflammatory Neuropathy Cause and Treatment overall disability score, the Rasch-built Overall Disability Scale, the Medical Research Council Sum Score and the INCAT-sensory sum-score. The interrelation between the five factors was assessed using analysis of variance and linear regression analysis.

RESULTS

Pain was reported in 62%, mostly of moderate and severe intensity, whereas pain characteristics indicated of neuropathic pain (NP) in 29%. Sensory dysfunction was stronger in NP-patients compared to pain-free patients (p=0.001). Pain of any type, especially NP, was associated with more pronounced fatigue symptoms (p=0.010). Depressive symptoms were more frequent in patients with pain compared to the pain-free patients (61% vs. 33%, p=0.02) and were more severe and frequent in NP-patients than in non-NP (p=0.005). Patients with pain had a worse physical quality of life than pain-free patients (p=0.001).

CONCLUSION

Pain, depression and fatigue are relevant disability factors in CIDP affecting quality of life. Sensory dysfunction is associated with NP. Therefore, evaluation of CIDP-related disability should include pain and sensory function for adequate monitoring of therapeutic interventions.

Comparison of diabetic and idiopathic sensory polyneuropathies with respect to nerve fibre affection and risk factors

Background and purpose

Chronic distal sensory or sensorimotor polyneuropathy is the most common pattern of polyneuropathy. The cause of this pattern is most often diabetes or unknown. This cross-sectional study is one of the first studies to compare the demographics, cardiovascular risk factors and clinical characteristics of diabetic polyneuropathy (DPN) with idiopathic polyneuropathy (IPN).

Methods

Patients with DPN were included from a sample of 389 patients with type 2 diabetes mellitus (T2DM) enrolled from a national cohort of patients with recently diagnosed T2DM (Danish Centre for Strategic Research in Type 2 Diabetes cohort). Patients with IPN were included from a regional cohort of patients with symptoms of polyneuropathy referred for workup at a combined secondary and tertiary neurological centre (database cohort).

Results

A total of 214 patients with DPN were compared with a total of 88 patients with IPN. Patients with DPN were older (67.4 vs 59 years) and had a longer duration of neuropathy symptoms. Patients with DPN had greater body mass index (32 vs 27.4 kg/m²) and waist circumference (110 cm vs 97 cm); higher frequency of hypertension diagnosis (72.9% vs 30.7%); lower total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels; and a higher prevalence of use of statins (81.8% vs 19.3%). DPN was associated with a slightly higher autonomic score and total score on the Neuropathy Symptom Score; lower frequency of hyperalgesia, allodynia and decreased vibration on quantitative sensory testing; lower intraepidermal nerve fibre density count and higher frequency of small-fibre neuropathy.

Conclusion

DPN and IPN showed clear differences in neuropathy characteristics, indicating that these two entities are to be regarded as aetiologically and pathogenetically distinct.

Cognitive function in diabetic persons with peripheral neuropathy: a systematic review and meta-analysis

OBJECTIVES

The aim of this study is to improve our knowledge of cognitive function in individuals with type 1 (T1DM) or type 2 (T2DM) diabetes mellitus and with peripheral diabetic neuropathy (DPN).

METHODS

A systematic review and meta-analysis was performed of publications included in PubMed, Scopus, PsycInfo and Web of Science databases until November 2021. The study protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) with reference number: CRD42021229163.

RESULTS

A total of 832 articles were identified, 19 of which were selected. The presence of DPN was associated with global cognitive impairment in the T1DM persons in two studies (p=0.046; p=0.03) and T2DM persons in four (p<0.001; p<0.02; p=0.011; p=<0.05). Differences in specific dimensions - memory, attention, and psychomotor speed - were found in both kinds of diabetes. The meta-analysis showed that the individuals with T2DM and DPN presented a lower mean cognitive performance than those without DPN (-1.0448; 95% CI: -1.93%; -0.16%). Depression was associated with impaired cognitive function in these diabetic persons (p<0.01).

CONCLUSION

The review reveals the great variability in instruments and methodologies, while providing results that support the presence of both global and domain-specific cognitive impairment in diabetic persons with DPN.

Neuropathic Pain in Neurologic Disorders: A Narrative Review

Neuropathic pain is defined as a painful condition caused by neurological lesions or diseases. Sometimes, neurological disorders may also be associated with neuropathic pain, which can be challenging to manage. For example, multiple sclerosis (MS) may cause chronic centralized painful symptoms due to nerve damage. Other chronic neuropathic pain syndromes may occur in the form of post-stroke pain, spinal cord injury pain, and other central pain syndromes. Chronic neuropathic pain is associated with dysfunction, disability, depression, disturbed sleep, and reduced quality of life. Early diagnosis may help improve outcomes, and pain control can be an important factor in restoring function. There are more than 100 different types of peripheral neuropathy and those involving sensory neurons can provoke painful symptoms. Accurate diagnosis of peripheral neuropathy is essential for pain control. Further examples are represented by gluten neuropathy, which is an extraintestinal manifestation of gluten sensitivity and presents as a form of peripheral neuropathy; in these unusual cases, neuropathy may be managed with diet. Neuropathic pain has been linked to CoronaVirus Disease (COVID) infection both during acute infection and as a post-viral syndrome known as long COVID. In this last case, neuropathic pain relates to the host’s response to the virus. However, neuropathic pain may occur after any critical illness and has been observed as part of a syndrome following intensive care unit hospitalization.

Intensive care unit-acquired weakness: Questions the clinician should ask

Intensive care unit (ICU)-acquired weakness (ICU-AW) is defined as clinically detected weakness in critically ill patients in whom there is no plausible etiology other than critical illness. Using electrophysiological methods, patients with ICU-AW are classified in three subcategories: critical illness polyneuropathy, critical illness myopathy and critical illness neuromyopathy. ICU-AW is a frequent complication occurring in critical ill patients. Risk factors include illness severity and organ failure, age, hyperglycemia, parenteral nutrition, drugs and immobility. Due to short- and long-term complications, ICU-AW results in longer hospital stay and increased mortality. Its management is essentially preventive avoiding modifiable risk factors, especially duration of sedation and immobilization that should be as short as possible. Pharmacological approaches have been studied but none have proven efficacy. In the present review, we propose practical questions that the clinician should ask in case of acquired weakness during ICU stay: when to suspect ICU-AW, what risk factors should be identified, how to diagnose ICU-AW, what is the prognosis and how can recovery be improved?

Physiological Changes and Pathological Pain Associated with Sedentary Lifestyle-Induced Body Systems Fat Accumulation and Their Modulation by Physical Exercise

A sedentary lifestyle is associated with overweight/obesity, which involves excessive fat body accumulation, triggering structural and functional changes in tissues, organs, and body systems. Research shows that this fat accumulation is responsible for several comorbidities, including cardiovascular, gastrointestinal, and metabolic dysfunctions, as well as pathological pain behaviors. These health concerns are related to the crosstalk between adipose tissue and body systems, leading to pathophysiological changes to the latter. To deal with these health issues, it has been suggested that physical exercise may reverse part of these obesity-related pathologies by modulating the cross talk between the adipose tissue and body systems. In this context, this review was carried out to provide knowledge about (i) the structural and functional changes in tissues, organs, and body systems from accumulation of fat in obesity, emphasizing the crosstalk between fat and body tissues; (ii) the crosstalk between fat and body tissues triggering pain; and (iii) the effects of physical exercise on body tissues and organs in obese and non-obese subjects, and their impact on pathological pain. This information may help one to better understand this crosstalk and the factors involved, and it could be useful in designing more specific training interventions (according to the nature of the comorbidity).

Myelination, axonal loss and Schwann cell characteristics in axonal polyneuropathy compared to controls

Introduction

Polyneuropathy is a debilitating condition characterized by distal sensory and motor deficits. Schwann cell dysfunction and axonal loss are integral factors in pathophysiology and disease progression of polyneuropathy.

Aims

The aim of this study was the assessment of Schwann cell characteristics, nerve fibers and myelination parameters in polyneuropathy patients compared to controls.

Methods

Nerve tissue was obtained from polyneuropathy patients (n = 10) undergoing diagnostic sural nerve biopsies. Biopsies of healthy peripheral nerves (n = 5) were harvested during elective sural nerve grafting for chronic peripheral nerve lesions. Exclusion criteria for the healthy control group were recent neurological trauma, diabetes, neurological and cardiovascular disease, as well as active malignancies and cytotoxic medication within the last 12 months. The over-all architecture of nerve sections and myelination parameters were histomorphometrically analyzed. Immunofluorescent imaging was used to evaluate Schwann cell phenotypes, senescence markers and myelination parameters.

Results

Histomorphometric analysis of nerve biopsies showed significant axonal loss in polyneuropathy patients compared to controls, which was in accordance with the neuropathological findings. Immunofluorescent staining of Schwann cells and myelin basic protein indicated a significant impairment of myelination and lower Schwann cell counts compared to controls. Phenotypic alterations and increased numbers of non-myelinating p75-positive Schwann cells were found in polyneuropathy patients.

Discussion

This study provided quantitative data of axonal loss, reduced myelination and Schwann cell dysfunction of polyneuropathy patients compared to neurologically healthy controls. Phenotypic alterations of Schwann cells were similar to those seen after peripheral nerve injury, highlighting the clinical relevance of Schwann cell dysfunction.

Electrodiagnostic Assessment of Polyneuropathy

This article focuses on principles of nerve conduction studies and needle electromyography applied to the electrodiagnosis of polyneuropathy. The components of the electrodiagnostic evaluation of polyneuropathy and the electrophysiological characteristics of axonal and demyelinating neuropathies and nodo-paranodopathies are reviewed.

Prediction of Diabetic Sensorimotor Polyneuropathy Using Machine Learning Techniques

Diabetic sensorimotor polyneuropathy (DSPN) is a major complication in patients with diabetes mellitus (DM), and early detection or prediction of DSPN is important for preventing or managing neuropathic pain and foot ulcer. Our aim is to delineate whether machine learning techniques are more useful than traditional statistical methods for predicting DSPN in DM patients. Four hundred seventy DM patients were classified into four groups (normal, possible, probable, and confirmed) based on clinical and electrophysiological findings of suspected DSPN. Three ML methods, XGBoost (XGB), support vector machine (SVM), and random forest (RF), and their combinations were used for analysis. RF showed the best area under the receiver operator characteristic curve (AUC, 0.8250) for differentiating between two categories—criteria by clinical findings (normal, possible, and probable groups) and those by electrophysiological findings (confirmed group)—and the result was superior to that of linear regression analysis (AUC = 0.6620). Average values of serum glucose, International Federation of Clinical Chemistry (IFCC), HbA1c, and albumin levels were identified as the four most important predictors of DSPN. In conclusion, machine learning techniques, especially RF, can predict DSPN in DM patients effectively, and electrophysiological analysis is important for identifying DSPN.

Alcohol Consumption as a Causator and/or an Accelerator of Neuropathy in People With Diabetes Is Regularly Overlooked

Patients with diabetes and distal symmetrical polyneuropathy (DSP) are routinely evaluated for etiologies other than diabetes, including vitamin B12 deficiency, paraproteinemia, hypothyroidism and drug or autoimmune-induced neuropathy. However, the most common cause of DSP, next to that of diabetes, is alcohol intake, which is almost never evaluated. In addition to assessment of alcohol intake based on patient history, which often leads to an underestimation of alchohol intake, markers of a high alcohol intake (elevated liver enzymes, uric acid, triglycerides, low magnesium or low folic acid levels) should be obtained. However, the test that is most likely to detect surreptitious alcohol intake is urinary ethyl glucuronide (EtG), which will detect the intake of alcohol within the previous 90 h. Detection of alcohol use is important since if alcohol consumption is not discontinued, DSP, whatever the etiology, will not improve. In addition, the use of drugs to improve symptoms of DSP (tricyclics, anti-epileptics, serotonin, norepinephrine reuptake inhibitors and analgesics) may in combination with alcohol excessively suppress respiration and cognitive function such that these drugs should not be prescribed or utilized if use of alcohol continues. In the future, all patients with DSP, and especially those with symptomatic DSP, should be biochemically screened for excessive alcohol intake and appropriate action taken.

A Retrospective Analysis of Pain Etiology in Middle-Aged Patients with Peripheral Neuropathy

Background and Objectives: Correct assessment and a multidisciplinary approach appear to be extremely important in preventing peripheral neuropathy and its complications. The purpose of this study was to find the correlations and dissimilarities between different types of peripheral neuropathy, the occurrence of pain, and laboratory results. Materials and Methods: This retrospective study assessed 124 patients who were hospitalized in our neurology department due to various types of sensory or motor disturbances. The patients were eventually diagnosed with peripheral neuropathy, based on the electrophysiological study, anamnesis, physical examination, and laboratory results. The whole group was subjected to statistical analysis. Results: The mean age of patients was over 56 years, with a slight woman predominance. A statistically significant (p < 0.05) relationship between the place of residence and gender was seen, where more men than women live in the rural area, while more women than men live in the urban area. Most often we observed symmetric, sensorimotor, demyelinating, inflammatory, and chronic neuropathy. More than 40% of patients reported pain. A statistically significant correlation between the evolution/severity and the occurrence of pain was seen in subacute type (p < 0.05) and small fibre neuropathy (p < 0.01). Conclusions: A higher incidence of peripheral neuropathy in middle-aged people will become essential in the aging society with lifestyle and chronic disorders. Peripheral neuropathy is slightly more common in women than men and its occurrence may be influenced by work performed or internal and external factors. In the study group, more than 40% of patients reported pain, therefore the pain measurement for each patient should be implemented and repeated at every visit. An assessment of sodium level and, in women, markers of neuroinflammation level in the various types of peripheral neuropathy may be an interesting direction for the future.

A Structured Approach to the Diagnosis of Peripheral Nervous System Disorders

PURPOSE OF REVIEW

Neuroanatomic localization and pattern recognition can be used to diagnose both focal lesions and generalized disorders of the peripheral nervous system. This article describes the nature and pattern of sensory and motor deficits associated with lesions of specific spinal nerve roots, plexus, or peripheral nerves. It also describes the patterns of sensory and motor deficits that suggest multifocal or generalized disorders of the motor neurons, sensory neurons, and peripheral nerves.

RECENT FINDINGS

The pattern of sensory and motor deficits may be used to distinguish lesions of the peripheral nervous system from those of the central nervous system. The spinal roots, nerve plexus, and peripheral nerves supply specific muscles and receive sensory input from distinctive cutaneous regions. Focal lesions of these structures therefore produce characteristic patterns of sensory and motor deficits. Multifocal or generalized disorders of the peripheral nervous system may be distinguished by categorizing their sensory and motor involvement, proximal and distal predominance, and degree of symmetry. Serum tests, CSF analysis, electrodiagnostic studies, MRI, ultrasound, nerve biopsy, and skin biopsy have unique roles in the diagnosis of suspected neuromuscular disorders.

SUMMARY

A structured approach to the diagnosis of nerve and motor neuron disorders can lead to hypothesis-driven diagnostic testing. Ancillary tests should be reserved for cases in which confirming or refuting a diagnosis will change patient management.

The Role of Neurotropic B Vitamins in Nerve Regeneration

Damage and regeneration naturally occur in the peripheral nervous system. The neurotropic B vitamins thiamine (B1), pyridoxine (B6), and cobalamin (B12) are key players, which maintain the neuronal viability in different ways. Firstly, they constantly protect nerves against damaging environmental influences. While vitamin B1 acts as a site-directed antioxidant, vitamin B6 balances nerve metabolism, and vitamin B12 maintains myelin sheaths. However, nerve injury occurs at times, because of an imbalance between protective factors and accumulating stress and noxae. This will result in the so-called Wallerian degeneration process. The presence of vitamins B1, B6, and B12 paves the way out to the following important regeneration by supporting the development of new cell structures. Furthermore, vitamin B1 facilitates the usage of carbohydrates for energy production, whereas vitamin B12 promotes nerve cell survival and remyelination. Absence of these vitamins will favor permanent nerve degeneration and pain, eventually leading to peripheral neuropathy.

Electrophysiologically verified effects of acupuncture on diabetic peripheral neuropathy in type 2 diabetes: The randomized, partially double-blinded, controlled ACUDIN trial

BACKGROUND

Acupuncture is commonly used in Traditional Chinese Medicine for treatment of diabetic peripheral neuropathy (DPN), but data from randomized controlled trials are rare.

METHODS

This randomized, placebo-controlled, partially double-blinded clinical trial randomly assigned adults with confirmed type 2 diabetes-induced DPN to receive 10 sessions of needle acupuncture, laser acupuncture, or placebo laser acupuncture for 10 consecutive weeks. Treatment was provided at bilateral acupoints Ex-LE-10 (Bafeng), Ex-LE-12 (Qiduan), and ST-34 (Lianqiu). Neurological assessments, including nerve conduction studies (NCS) of sural and tibial nerves, were performed at baseline and weeks 6 and 15. Primary outcome was delta of sural sensory nerve action potential (SNAP). Secondary outcomes included further NCS values, clinical scores, and patient-reported outcome measures (PROMs).

RESULTS

Of 180 participants, 172 completed the study. Sural SNAP and sural and tibial nerve conduction velocities improved significantly after 10 treatments when comparing needle acupuncture to placebo. Needle acupuncture showed earlier onset of action than laser acupuncture. PROMs showed larger improvements following needle and laser acupuncture than placebo, reaching significant differences for hyperesthesia and cramps following needle acupuncture and for heat sensation following laser acupuncture.

CONCLUSIONS

Classical needle acupuncture had significant effects on DPN. Improvement in NCS values presumably indicates structural neuroregeneration following acupuncture.

Prevalence and incidence of diabetic peripheral neuropathy in Latin America and the Caribbean: A systematic review and meta-analysis

AIMS

The objective of this systematic review and meta-analysis is to estimate the prevalence and incidence of diabetic peripheral neuropathy (DPN) in Latin America and the Caribbean (LAC).

MATERIALS AND METHODS

We searched MEDLINE, SCOPUS, Web of Science, EMBASE and LILACS databases of published observational studies in LAC up to December 2020. Meta-analyses of proportions were performed using random-effects models using Stata Program 15.1. Heterogeneity was evaluated through sensitivity, subgroup, and meta-regression analyses. Evidence certainty was performed with the GRADE approach.

RESULTS

Twenty-nine studies from eight countries were included. The estimated prevalence of DPN was 46.5% (95%CI: 38.0-55.0) with a significant heterogeneity (I2 = 98.2%; p<0.01). Only two studies reported incidence, and the pooled effect size was 13.7% (95%CI: 10.6-17.2). We found an increasing trend of cumulative DPN prevalence over time. The main sources of heterogeneity associated with higher prevalence were diagnosis criteria, higher A1c (%), and inadequate sample size. We judge the included evidence as very low certainty.

CONCLUSION

The overall prevalence of DPN is high in LAC with significant heterogeneity between and within countries that could be explained by population type and methodological aspects. Significant gaps (e.g., under-representation of most countries, lack of incidence studies, and heterogenous case definition) were identified. Standardized and population-based studies of DPN in LAC are needed.

Patients who meet electrodiagnostic criteria for CIDP rarely present with a sensory predominant DSP phenotype

INTRODUCTION

It is unknown how often patients with electrodiagnostic evidence of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), a potentially treatable condition, present with a distal symmetric polyneuropathy (DSP) phenotype.

METHODS

We reviewed the records of patients who presented to our electrodiagnostic laboratory between January 1, 2011, to December 31, 2019, and fulfilled electrodiagnostic criteria for CIDP to identify those who presented with a sensory predominant DSP phenotype.

RESULTS

One hundred sixty-two patients had a chronic acquired demyelinating neuropathy, of whom 138 met criteria for typical or atypical CIDP. Nine of these patients presented with a sensory predominant DSP phenotype, among whom six were eventually diagnosed with distal acquired demyelinating symmetric (DADS) neuropathy; one with Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal protein, Skin changes (POEMS) syndrome; and two with idiopathic DSP. The prevalence of acquired chronic demyelinating neuropathies among all patients presenting with a DSP phenotype was estimated to be 0.34%.

DISCUSSION

Patients who meet electrodiagnostic criteria for CIDP rarely present with a sensory predominant DSP phenotype, and electrodiagnostic testing rarely identifies treatable demyelinating neuropathies in patients who present with a DSP phenotype.

Painful and non-painful diabetic neuropathy, diagnostic challenges and implications for future management

Peripheral neuropathy is one of the most common complications of both type 1 and type 2 diabetes. Up to half of patients with diabetes develop neuropathy during the course of their disease, which is accompanied by neuropathic pain in 30-40% of cases. Peripheral nerve injury in diabetes can manifest as progressive distal symmetric polyneuropathy, autonomic neuropathy, radiculo-plexopathies, and mononeuropathies. The most common diabetic neuropathy is distal symmetric polyneuropathy, which we will refer to as DN, with its characteristic glove and stocking like presentation of distal sensory or motor function loss. DN or its painful counterpart, painful DN, are associated with increased mortality and morbidity; thus, early recognition and preventive measures are essential. Nevertheless, it is not easy to diagnose DN or painful DN, particularly in patients with early and mild neuropathy, and there is currently no single established diagnostic gold standard. The most common diagnostic approach in research is a hierarchical system, which combines symptoms, signs, and a series of confirmatory tests. The general lack of long-term prospective studies has limited the evaluation of the sensitivity and specificity of new morphometric and neurophysiological techniques. Thus, the best paradigm for screening DN and painful DN both in research and in clinical practice remains uncertain. Herein, we review the diagnostic challenges from both clinical and research perspectives and their implications for managing patients with DN. There is no established DN treatment, apart from improved glycaemic control, which is more effective in type 1 than in type 2 diabetes, and only symptomatic management is available for painful DN. Currently, less than one-third of patients with painful DN derive sufficient pain relief with existing pharmacotherapies. A more precise and distinct sensory profile from patients with DN and painful DN may help identify responsive patients to one treatment versus another. Detailed sensory profiles will lead to tailored treatment for patient subgroups with painful DN by matching to novel or established DN pathomechanisms and also for improved clinical trials stratification. Large randomized clinical trials are needed to identify the interventions, i.e. pharmacological, physical, cognitive, educational, etc., which lead to the best therapeutic outcomes.

Diabetic neuropathy in children and youth: New and emerging risk factors

Pediatric neuropathy attributed to metabolic dysfunction is a well-known complication in children and youth with type 1 diabetes. Moreover, the rise of obesity and in particular of type 2 diabetes may cause an uptick in pediatric neuropathy incidence. However, despite the anticipated increase in neuropathy incidence, pathogenic insights and strategies to prevent or manage neuropathy in the setting of diabetes and obesity in children and youth remain unknown. Data from adult studies and available youth cohort studies are providing an initial understanding of potential diagnostic, management, and preventative measures in early life. This review discusses the current state of knowledge emanating from these efforts, with particular emphasis on the prevalence, clinical presentation, diagnostic approaches and considerations, and risk factors of neuropathy in type 1 and type 2 diabetes in children and youth. Also highlighted are current management strategies and recommendations for neuropathy in children and youth with diabetes. This knowledge, along with continued and sustained emphasis on identifying and eliminating modifiable risk factors, completing randomized controlled trials to assess effectiveness of strategies like weight loss and exercise, and enhancing awareness to support early detection and prevention, are pertinent to addressing the rising incidence of neuropathy associated with diabetes and obesity in children and youth.

Attenuation of ongoing neuropathic pain by peripheral acting opioid involves activation of central dopaminergic neurocircuitry

BACKGROUND AND PURPOSE

Ongoing neuropathic pain is one of the most challenging clinical problems which have detrimental effects on a patient's life quality. Conventional therapies for chronic neuropathic pain majorly includes centrally acting analgesics. Unfortunately, the unceasing use of these drugs results in adverse effects, such as CNS in-coordination, respiratory depression and substance use disorder. DALDA ([D-Arg², Lys⁴]-Dermorphin-(1-4)-amide), a peripherally acting opioid have been shown to possess potent analgesic activity without causing CNS toxicities in nerve-injured rats. However, the mechanism(s) underpinning DALDA induced-attenuation of ongoing neuropathic pain is yet to identify [1].

EXPERIMENTAL DESIGN

In this study, we have measured the in-silico ligand-receptor binding affinity of DALDA against potential inflammatory targets by utilizing glide module of schrödinger software. Effect of DALDA on oxido-inflammatory stress was evaluated in LPS-induced C6 glial cells. In-vitro studies were followed by the behavioral assessments, where effect of DALDA was measured in chronic constriction injured rats. To examine the effect of DALDA on dopaminergic neurotransmission, cerebrospinal fluid of nerve-injured rats was assessed using LC-MS/QToF (Liquid Chromatography-Mass spectrometry/ Quadrapole time of flight Analyzer).

RESULTS

DALDA has shown a good binding affinity with chemokine receptor type-2 (CCR2), chemokine CX3C receptor 1 (CX3CR1) and purinergic receptor (P2×4), major receptor subtypes involved in pain and inflammation. Findings from the in-vitro studies suggest that DALDA possesses potent anti-oxidant activity leading to inhibition of p38-MAPK pathway [1]. Moreover, the subcutaneous administration of DALDA leads to dose-dependent attenuation of thermal and mechanical hypersensitivity along with inhibition of neuroinflammatory mediators in serum and spinal cord of nerve-injured rats. Most importantly, DALDA treated neuropathic rats showed a preference for the DALDA-treated chamber, which was attenuated on pre-treatment with dopaminergic receptor antagonist, flupenthixol. LC-MS analysis further confirms the enhanced dopaminergic transmission in the brain of DALDA-treated neuropathic rats.

CONCLUSION

Our findings suggest that DALDA mediated attenuation of ongoing neuropathic pain may be associated with a decrease in spinal neuroinflammatory signalling and subsequent increase in the brain dopamine level; may serve a potential therapeutic for the treatment of ongoing neuropathic pain.

Remote Photoplethysmography for Evaluation of Cutaneous Sensory Nerve Fiber Function

About 2% of the world’s population suffers from small nerve fiber dysfunction, neuropathy, which can result in severe pain. This condition is caused by damage to the small nerve fibers and its assessment is challenging, due to the lack of simple and objective diagnostic techniques. The present study aimed to develop a contactless photoplethysmography system using simple instrumentation, for objective and non-invasive assessment of small cutaneous sensory nerve fiber function. The approach is based on the use of contactless photoplethysmography for the characterization of skin flowmotions and topical heating evoked vasomotor responses. The feasibility of the technique was evaluated on volunteers (n = 14) using skin topical anesthesia, which is able to produce temporary alterations of cutaneous nerve fibers function. In the treated skin region in comparison to intact skin: neurogenic and endothelial component of flowmotions decreased by ~61% and 41%, the local heating evoked flare area decreased by ~44%, vasomotor response trend peak and nadir were substantially reduced. The results indicate for the potential of the remote photoplethysmography in the assessment of the cutaneous nerve fiber function. It is believed that in the future this technique could be used in the clinics as an affordable alternative to laser Doppler imaging technique.

Distal Symmetric Polyneuropathy Identification in Type 2 Diabetes Subjects: A Random Forest Approach

The prevalence of diabetes mellitus is increasing worldwide, causing health and economic implications. One of the principal microvascular complications of type 2 diabetes is Distal Symmetric Polyneuropathy (DSPN), affecting 42.6% of the population in Mexico. Therefore, the purpose of this study was to find out the predictors of this complication. The dataset contained a total number of 140 subjects, including clinical and paraclinical features. A multivariate analysis was constructed using Boruta as a feature selection method and Random Forest as a classification algorithm applying the strategy of K-Folds Cross Validation and Leave One Out Cross Validation. Then, the models were evaluated through a statistical analysis based on sensitivity, specificity, area under the curve (AUC) and receiving operating characteristic (ROC) curve. The results present significant values obtained by the model with this approach, presenting 67% of AUC with only three features as predictors. It is possible to conclude that this proposed methodology can classify patients with DSPN, obtaining a preliminary computer-aided diagnosis tool for the clinical area in helping to identify the diagnosis of DSPN.

A systematic review and meta-analysis of the serum lipid profile in prediction of diabetic neuropathy

Whether the lipid profile in diabetic patients is associated with diabetic neuropathy (DN) development remains ambiguous, as does the predictive value of serum lipid levels in the risk of DN. Here, we performed the first meta-analysis designed to investigate the relationship between DN and the serum levels of triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL). Candidate studies were comprehensively identified by searching PubMed, Embase, Cochrane Library and Web of Science databases up to May 2020. Observational methodological meta-analysis was conducted to assess the relationships of TG, TC, HDL, and LDL levels with DN. Changes in blood lipids were used to estimate the effect size. The results were pooled using a random-effects or fixed-effects model. Potential sources of heterogeneity were explored by subgroup analysis. Various outcomes were included, and statistical analyses were performed using STATA (Version 12.0). Mean differences (MDs) and odds ratios (ORs) with 95% confidence intervals (CIs) were estimated. The Newcastle–Ottawa Scale (NOS) was applied to assess the methodological quality. I2 statistics were calculated to evaluate statistical heterogeneity. Funnel plots were utilized to test for publication bias. A sensitivity analysis was performed by omitting each study one by one. Thirty-nine clinical trials containing 32,668 patients were included in the meta-analysis. The results demonstrated that DN patients showed higher TG and lower HDL levels (MD = 0.34, 95% CI: 0.20–0.48 for TG; MD = -0.05, 95% CI: -0.08–-0.02, I² = 81.3% for HDL) than controls. Subgroup analysis showed that patients with type 1 diabetes mellitus (T1DM) neuropathy had elevated TG levels in their serum (MD = 0.25, 95% CI: 0.16–0.35,I² = 64.4% for T1DM). However, only patients with T1DM neuropathy had reduced serum HDL levels, and there was no significant difference in serum HDL levels between patients with T2DM neuropathy and controls (MD = -0.07, 95% CI: -0.10–-0.03, I² = 12.4% for T1DM; MD = -0.02, 95% CI: -0.07–0.03, I² = 80.2% for T2DM). TC and LDL levels were not significantly different between DN patients and controls (MD = -0.03, 95% CI: -0.14–0.09, I² = 82.9% for TC; MD = -0.00, 95% CI: -0.08–0.08, I² = 78.9% for LDL). In addition, compared with mild or painless DN patients, those with moderate or severe pain DN pain had significantly reduced serum TC and LDL levels (MD = -0.31, 95% CI: -0.49–-0.13, I² = 0% for TC; MD = -0.19, 95% CI: -0.32–-0.08, I² = 0% for LDL). TG levels and HDL levels did not vary considerably between patients with mild or painless DN and those with moderate or severe DN pain patients (MD = 0.12, 95% CI: -0.28–0.51, I² = 83.2% for TG; MD = -0.07, 95% CI:-0.14–0.01, I² = 58.8% for HDL). Furthermore, people with higher TG and LDL levels had higher risk of DN (OR = 1.36, 95% CI: 1.20–1.54, I² = 86.1% for TG and OR = 1.10, 95% CI: 1.02–1.19, I² = 17.8% for LDL). Conversely, high serum HDL levels reduced the risk of DN (OR = 0.85, 95% CI: 0.75–0.96, I² = 72.6%), while TC levels made no significant difference with the risk of DN (OR = 1.02, 95% CI: 1.00–1.04, I² = 84.7%). This meta-analysis indicated that serum lipid profile changes are among the biological characteristics of DN. Lipid levels should be explored as routine laboratory markers for predicting the risk of DN, as they will help clinicians choose appropriate therapies, and thus optimize the use of available resources.

The role and therapeutic potential of Hsp90, Hsp70, and smaller heat shock proteins in peripheral and central neuropathies

Heat shock proteins (Hsps) are molecular chaperones that also play important roles in the activation of the heat shock response (HSR). The HSR is an evolutionary conserved and protective mechanism that is used to counter abnormal physiological conditions, stressors, and disease states, such as those exemplified in cancer and/or neurodegeneration. In normal cells, heat shock factor-1 (HSF-1), the transcription factor that regulates the HSR, remains in a dormant multiprotein complex that is formed upon association with chaperones (Hsp90, Hsp70, etc.), co-chaperones, and client proteins. However, under cellular stress, HSF-1 dissociates from Hsp90 and induces the transcriptional upregulation of Hsp70 to afford protection against the encountered cellular stress. As a consequence of both peripheral and central neuropathies, cellular stress occurs and results in the accumulation of unfolded and/or misfolded proteins, which can be counterbalanced by activation of the HSR. Since Hsp90 is the primary regulator of the HSR, modulation of Hsp90 by small molecules represents an attractive therapeutic approach against both peripheral and central neuropathies.

Dorsal Root Ganglion Stimulation for the Management of Intractable Painful Polyneuropathy: A Prospective Pilot Study

OBJECTIVES

Dorsal root ganglion stimulation (DRGS) is a promising neurostimulation modality in the treatment of painful polyneuropathy. The aim of this prospective pilot study was to investigate the effect of DRGS on pain intensity in patients with intractable painful polyneuropathy.

MATERIALS AND METHODS

Nine patients with chronic, intractable painful polyneuropathy in the lower limbs were recruited. In each subject, between two and four DRGS leads were placed at the level of the L5 and S1 dorsal root ganglion. If trial stimulation was successful, a definitive implantable pulse generator (IPG) was implanted. Pain intensity was scored using an 11-point numeric rating scale (NRS) and reported as median and interquartile range (IQR), and compared to baseline values using the Wilcoxon signed-rank test. Additionally, patients' global impression of change (PGIC), pain extent, presence of neuropathic pain, physical functioning, quality of life, and mood were assessed.

RESULTS

Eight out of nine patients had a successful trial phase, of which seven received an IPG. Daytime pain decreased from a median (IQR) NRS score of 7.0 (5.9-8.3) to 2.0 (1.0-3.5) and 3.0 (1.6-4.9) in the first week and at six months after implantation, respectively. Similar effects were observed for night time and peak pain scores.

CONCLUSIONS

The results of this study suggest that DRGS significantly reduces both pain intensity and PGIC in patients with intractable painful polyneuropathy in the lower extremities. Large-scale clinical trials are needed to prove the efficacy of DRGS in intractable painful polyneuropathy.

Imaging Review of Peripheral Nerve Injuries in Patients with COVID-19

With surging numbers of patients with coronavirus disease 2019 (COVID-19) throughout the world, neuromuscular complications and rehabilitation concerns are becoming more apparent. Peripheral nerve injury can occur in patients with COVID-19 secondary to postinfectious inflammatory neuropathy, prone positioning-related stretch and/or compression injury, systemic neuropathy, or nerve entrapment from hematoma. Imaging of peripheral nerves in patients with COVID-19 may help to characterize nerve abnormality, to identify site and severity of nerve damage, and to potentially elucidate mechanisms of injury, thereby aiding the medical diagnosis and decision-making process. This review article aims to provide a first comprehensive summary of the current knowledge of COVID-19 and peripheral nerve imaging.

What Every Neuropathologist Needs to Know: Peripheral Nerve Biopsy

Peripheral neuropathy is a common disorder with many possible etiologies including metabolic diseases, inflammatory conditions, infections, malignancy, inherited diseases, drugs, and toxins. In most instances, diagnosis and treatment plan can be established based on clinical presentation, family history, laboratory results, genetic testing, and electrophysiological studies. But in some situations, a peripheral nerve biopsy remains a valuable tool. This is especially true in patients with rapidly progressive disease, with atypical presentation or for whom other approaches fail to yield a definitive diagnosis. The pathologic examination starts with basic decisions about specimen triage. A few basic questions help to provide an initial framework for the assessment of a nerve biopsy-is the specimen adequate; are there inflammatory changes; are there vascular changes; is there amyloid; are there changes to axonal density and the Schwann cell-myelin-axon unit. In the appropriate context and with such an approach peripheral nerve biopsies can still represent a clinically helpful test.

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.

Test Utilization and Value in the Evaluation of Peripheral Neuropathies

Peripheral neuropathies can be classified as typical or atypical. Patients with atypical neuropathy have one or more of the following features: acute/subacute onset, non-length dependence, motor predominance, or asymmetry. This classification is important because it informs the appropriate diagnostic evaluation of this highly prevalent condition. The evaluation of a typical peripheral neuropathy, also known as distal symmetric polyneuropathy, requires a thorough history, neurologic examination, and focused laboratory testing. Electrodiagnostic testing and MRI account for the majority of costs but rarely lead to changes in diagnosis or management. These costs are increasingly being passed on to patients, especially those with high-deductible health plans. In contrast, patients with atypical neuropathy require more extensive testing, including electrodiagnostic tests. These tests are much more likely to lead to the use of disease-modifying therapies in these patients compared to in those with typical peripheral neuropathy. This article describes two cases to illustrate the appropriate diagnostic workup of those with typical or atypical neuropathy.

Diagnosis and prevalence of diabetic polyneuropathy: a cross-sectional study of Danish patients with type 2 diabetes

BACKGROUND AND PURPOSE

Diabetic polyneuropathy (DPN) is a common complication of diabetes. Using the Toronto criteria for diabetic polyneuropathy and the grading system for neuropathic pain, the performance of neuropathy scales and questionnaires were assessed by comparing them to a clinical gold standard diagnosis of DPN and painful DPN in a cohort of patients with recently diagnosed type 2 diabetes.

METHODS

A questionnaire on neuropathy and pain was sent to a cohort of 5514 Danish type 2 diabetes patients. A sample of 389 patients underwent a detailed clinical examination and completed neuropathy questionnaires and scales.

RESULTS

Of the 389 patients with a median diabetes duration of 5.9 years, 126 had definite DPN (including 53 with painful DPN), 88 had probable DPN and 53 had possible DPN. There were 49 patients with other causes of polyneuropathy, neuropathy symptoms or pain, 10 with subclinical DPN and 63 without DPN. The sensitivity of the Michigan Neuropathy Screening Instrument questionnaire to detect DPN was 25.7% and the specificity 84.6%. The sensitivity of the Toronto Clinical Neuropathy Scoring System, including questionnaire and clinical examination, was 62.9% and the specificity was 74.6%.

CONCLUSIONS

Diabetic polyneuropathy affects approximately one in five Danish patients with recently diagnosed type 2 diabetes but neuropathic pain is not as common as previously reported. Neuropathy scales with clinical examination perform better compared with questionnaires alone, but better scales are needed for future epidemiological studies.

Genome-wide profiling of DNA methylation and gene expression identifies candidate genes for human diabetic neuropathy

BACKGROUND

Diabetic peripheral neuropathy (DPN) is the most common complication of type 2 diabetes (T2D). Although the cellular and molecular mechanisms of DPN are poorly understood, we and others have shown that altered gene expression and DNA methylation are implicated in disease pathogenesis. However, how DNA methylation might functionally impact gene expression and contribute to nerve damage remains unclear. Here, we analyzed genome-wide transcriptomic and methylomic profiles of sural nerves from T2D patients with DPN.

RESULTS

Unbiased clustering of transcriptomics data separated samples into groups, which correlated with HbA1c levels. Accordingly, we found 998 differentially expressed genes (DEGs) and 929 differentially methylated genes (DMGs) between the groups with the highest and lowest HbA1c levels. Functional enrichment analysis revealed that DEGs and DMGs were enriched for pathways known to play a role in DPN, including those related to the immune system, extracellular matrix (ECM), and axon guidance. To understand the interaction between the transcriptome and methylome in DPN, we performed an integrated analysis of the overlapping genes between DEGs and DMGs. Integrated functional and network analysis identified genes and pathways modulating functions such as immune response, ECM regulation, and PI3K-Akt signaling.

CONCLUSION

These results suggest for the first time that DNA methylation is a mechanism regulating gene expression in DPN. Overall, DPN patients with high HbA1c have distinct alterations in sural nerve DNA methylome and transcriptome, suggesting that optimal glycemic control in DPN patients is an important factor in maintaining epigenetic homeostasis and nerve function.

Peripheral neuropathy symptoms in wild type transthyretin amyloidosis

To propose a correlation between polyneuropathy and ATTRwt based on retrospective analysis of patients with ATTRwt. We reviewed 151 ATTRwt patients followed by the amyloid cardiac clinic (group A) for symptoms of neuropathy and 12 patients with ATTRwt evaluated in the Neurology Department (group B) with objective measures of neuropathy. Medical history, electrodiagnosis, laboratory and skin biopsies were assessed; 30.5% of group A had neuropathy symptoms. Alternative explanations for neuropathy symptoms were explored, including, age, gender, BMI, diabetes mellitus, B12 deficiency. No difference was observed for BMI, age, gender and spine disease for those with and without neuropathic symptoms (P > .05). All of group B (n = 12) were diagnosed with neuropathy, confirmed by electrodiagnostic testing or skin biopsy, while two patients had not yet developed cardiac symptoms. We observe a higher prevalence of neuropathic symptoms in ATTRwt patients than previously believed. Neuropathic symptoms may precede cardiac symptoms. Our findings suggest a possible causative relationship that requires further investigation.

Diagnosis of peripheral neuropathy

Introduction

Peripheral neuropathy represents a spectrum of diseases with different etiologies. The most common causes are diabetes, exposure to toxic substances including alcohol and chemotherapeutics, immune-mediated conditions, and gene mutations. A thorough workup including clinical history and examination, nerve conduction studies, and comprehensive laboratory tests is warranted to identify treatable causes.

First steps

The variability of symptoms allows distinguishing characteristic clinical phenotypes of peripheral neuropathy that should be recognized in order to stratify the diagnostic workup accordingly. Nerve conduction studies are essential to determine the phenotype (axonal versus demyelinating) and severity. Laboratory tests, including genetic testing, CSF examination, nerve imaging, and nerve biopsy, represent additional clinical tests that can be useful in specific clinical scenarios.

Comments

We propose a flow chart based on five common basic clinical patterns of peripheral neuropathy. Based on these five clinical phenotypes, we suggest differential diagnostic pathways in order to establish the underlying cause.

Conclusions

The recognition of characteristic clinical phenotypes combined with nerve conduction studies allows pursuing subsequent diagnostic pathways that incorporate nerve conduction studies and additional diagnostic tests. This two-tiered approach promises higher yield and better cost-effectiveness in the diagnostic workup in patients with peripheral neuropathy.

Clinical diagnosis and management of small fiber neuropathy: an update on best practice

INTRODUCTION

Small fiber neuropathy (SFN) is a heterogeneous group of disorders affecting thin myelinated Aδ and unmyelinated C fibers. Common symptoms include neuropathic pain and autonomic disturbances, and the typical clinical presentation is that of a length-dependent polyneuropathy, although other distributions could be present.

AREA COVERED

This review focuses on several aspects of SFN including etiology, clinical presentation, diagnostic criteria and tests, management, and future perspectives. Diagnostic challenges are discussed, encompassing the role of accurate and standardized assessment of symptoms and signs and providing clues for the clinical practice. The authors discuss the evidence in support of skin biopsy and quantitative sensory testing as diagnostic tests and present an overview of other diagnostic techniques to assess sensory and autonomic fibers dysfunction. The authors also suggest a systematic approach to the etiology including a set of laboratory tests and genetic examinations of sodium channelopathies and other rare conditions that might drive the therapeutic approach based on underlying cause or symptoms treatment.

EXPERT OPINION

SFN provides a useful model for neuropathic pain whose known mechanisms and cause could pave the way toward personalized treatments.

Corneal nerve loss in children with type 1 diabetes mellitus without retinopathy or microalbuminuria

Aims/Introduction

Corneal confocal microscopy is a rapid, non‐invasive ophthalmic technique to identify subclinical neuropathy. The aim of this study was to quantify corneal nerve morphology in children with type 1 diabetes mellitus compared with age‐matched healthy controls using corneal confocal microscopy.

Materials and Methods

A total of 20 participants with type 1 diabetes mellitus (age 14 ± 2 years, diabetes duration 4.08 ± 2.91 years, glycated hemoglobin 9.3 ± 2.1%) without retinopathy or microalbuminuria and 20 healthy controls were recruited from outpatient clinics. Corneal confocal microscopy was undertaken, and corneal nerve fiber density (n/mm²), corneal nerve branch density (n/mm²), corneal nerve fiber length (mm/mm²), corneal nerve fiber tortuosity and inferior whorl length (mm/mm²) were quantified manually.

Results

Corneal nerve fiber density (22.73 ± 8.84 vs 32.92 ± 8.59; P < 0.001), corneal nerve branch density (26.19 ± 14.64 vs 47.34 ± 20.01; P < 0.001), corneal nerve fiber length (13.26 ± 4.06 vs 19.52 ± 4.54; P < 0.001) and inferior whorl length (15.50 ± 5.48 vs 23.42 ± 3.94; P < 0.0001) were significantly lower, whereas corneal nerve fiber tortuosity (14.88 ± 5.28 vs 13.52 ± 3.01; P = 0.323) did not differ between children with type 1 diabetes mellitus and controls. Glycated hemoglobin correlated with corneal nerve fiber tortuosity (P < 0.006) and aspartate aminotransferase correlated with corneal nerve fiber density (P = 0.039), corneal nerve branch density (P = 0.003) and corneal nerve fiber length (P = 0.037).

Conclusion

Corneal confocal microscopy identifies significant subclinical corneal nerve loss, especially in the inferior whorl of children with type 1 diabetes mellitus without retinopathy or microalbuminuria.

Guidelines on multidisciplinary approaches for the prevention and management of diabetic foot disease (2020 edition)

In recent years, as living standards have continued to improve, the number of diabetes patients in China, along with the incidence of complications associated with the disease, has been increasing. Among these complications, diabetic foot disease is one of the main causes of disability and death in diabetic patients. Due to the differences in economy, culture, religion and level of medical care available across different regions, preventive and treatment methods and curative results for diabetic foot vary greatly. In multidisciplinary models built around diabetic foot, the timely assessment and diagnosis of wounds and appropriate methods of prevention and treatment with internal and external surgery are key to clinical practice for this pathology. In 2019, under the leadership of the Jiangsu Medical Association and Chinese Diabetes Society, the writing group for the Guidelines on multidisciplinary approaches for the prevention and management of diabetic foot disease (2020 edition) was established with the participation of scholars from the specialist areas of endocrinology, burn injury, vascular surgery, orthopedics, foot and ankle surgery and cardiology. Drawing lessons from diabetic foot guidelines from other countries, this guide analyses clinical practices for diabetic foot, queries the theoretical basis and grades and gives recommendations based on the characteristics of the pathology in China. This paper begins with assessments and diagnoses of diabetic foot, then describes treatments for diabetic foot in detail, and ends with protections for high-risk feet and the prevention of ulcers. This manuscript covers the disciplines of internal medicine, surgical, nursing and rehabilitation and describes a total of 50 recommendations that we hope will provide procedures and protocols for clinicians dealing with diabetic foot.

Registry number: IPGRP-2020cn124

Diabetic Distal Symmetrical Polyneuropathy: Correlation of Clinical, Laboratory, and Electrophysiologic Studies in Patients with Type 2 Diabetes Mellitus

This cross-sectional study is aimed at determining the prevalence of distal symmetrical polyneuropathy (DSPN) and diabetic peripheral neuropathic pain (DPNP) in participants with type 2 diabetes mellitus (T2DM); finding the risk factors for DSPN and DPNP via biochemical tests; and correlating DSPN and DPNP with the results of electrophysiologic studies, quantitative sensory tests, and neurologic examination. The 145 participants with T2DM enrolled were divided into the DSPN (abnormal nerve conduction studies (NCS) with signs of polyneuropathy), subclinical DSPN (abnormal NCS without signs of polyneuropathy), minimal DSPN (normal NCS with signs of polyneuropathy), and no DSPN groups. The biochemical risk factors of diabetic peripheral neuropathy were investigated. Neurologic examinations, laboratory tests, NCS, vibration threshold tests, and thermal threshold tests were conducted. The modified Michigan Neuropathy Screening Instrument (mMNSI) and Douleur Neuropathique 4 were used to evaluate the severity of DSPN and DPNP, respectively. In all, 30% of participants had DSPN and 11% had DPNP. DSPN correlated strongly with male gender and higher glycohaemoglobin levels; NCS abnormality correlated with higher glycohaemoglobin levels; DSPN severity correlated with NCS of each stimulating nerve. DPNP commonly occurred with clinical and electrophysiologic evidence of DSPN. Symptomatic diabetic polyneuropathy significantly correlated with longer disease duration, higher glycohaemoglobin levels, and abnormal vibration tests. The thermal threshold test combined with nerve conduction tests could detect most of the patients with DSPN, subclinical DSPN, and minimal DSPN. Poor diabetic control was independently associated with the development of DSPN. DPNP was associated with DSPN. The combination of thermal threshold tests with NCS can potentially provide the diagnosis of DSPN.