Alpha lipoic Acid for symptomatic peripheral neuropathy in patients with diabetes: a meta-analysis of randomized controlled trials

Biomarkers of response to alpha-lipoic acid ± palmitoiletanolamide treatment in patients with diabetes and symptoms of peripheral neuropathy

PURPOSE

To evaluate the effect of oral alpha-lipoic acid (ALA) ± palmitoyl-ethanolamide (PEA) on neuropathic symptoms in patients with diabetic peripheral neuropathy (DPN) and to identify factors related to the efficacy of the treatment.

METHODS

This is a retrospective observational pilot study evaluating 49 patients with diabetes and positive Neuropathy Symptoms Score (NSS). Clinical and biochemical variables, including NSS, were compared between untreated patients and patients treated with oral 600 mg/day ALA ± 600 mg/day PEA at baseline (first occurrence of NSS ≥ 3) and at least 2 months after baseline. Number of days between treatment initiation and symptoms' relief and related factors were also investigated.

RESULTS

Thirty subjects were treated with ALA ± PEA and 19 subjects did not receive any specific treatment for neuropathy symptoms. Follow-up visits occurred after 98 ± 46 days. NSS significantly decreased in patients treated with ALA ± PEA (5.4 ± 1.3 at baseline vs. 1.7 ± 2.4 at follow-up, p < 0.001), but not in untreated patients (p = 0.164). Subjects treated with ALA ± PEA reported a mean time from treatment initiation to symptoms' relief of 18.4 ± 9.0 days. The number of days of treatment needed for symptoms' relief was inversely related to HDL-cholesterol levels (r = -0.503, p = 0.010) and to eGFR (r = -0.428, p = 0.033), whereas there was no significant relationship between time to symptoms' relief and age, HbA1c, lipid profile and the severity of symptoms at baseline.

CONCLUSIONS

This study documents that oral administration of ALA ± PEA helps in controlling neuropathy symptoms in diabetes. Moreover, our data show that higher HDL-c levels and better renal function are associated to a faster therapeutic effect, suggesting them as biomarkers of response to therapy with ALA ± PEA.

Alpha lipoic acid supplementation improved antioxidant enzyme activities in hemodialysis patients

Background: Cardiovascular disease (CVD) is the main cause of death in hemodialysis (HD) patients and oxidative stress is an important risk factor for CVD. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) are primary antioxidant enzymes in human cells acting against toxic reactive oxygen species (ROS) and their reduced activity may contribute to oxidative disorders in HD patients. Alpha lipoic acid (ALA) as a potent strong antioxidant may affect these enzymes. Objective: We examined the effects of ALA supplementation on antioxidant enzyme activities in HD patients. Method: In this double-blinded, randomized clinical trial, 63 HD patients (43 males and 20 females; age range: 22-79 years) were assigned into the ALA group (n: 31), receiving a daily dose of ALA (600 mg), or a control group (n: 32), receiving placebo for 8 weeks. Body mass index (BMI), antioxidant enzymes, albumin (Alb) and hemoglobin (Hb) were determined before and after intervention. Results: At baseline, the mean blood activities of SOD, GPx, and CAT in ALA group were 1032±366, 18.9±5.09 and 191±82.7 U/gHb which increased at the end of study to 1149±502, 19.1±7.19 and 208±86.6 U/gHb respectively. However, only the increase of SOD was statistically significant in comparison with placebo group (P = 0.04). The mean levels of Alb, Hb, weight and BMI were not significantly changed in study groups (P>0.05). Conclusion: ALA may be beneficial for HD patients by increasing the activity of antioxidant enzymes; however, further studies are needed to achieve precise results.

Emerging Biomarkers, Tools, and Treatments for Diabetic Polyneuropathy

Diabetic neuropathy, with its major clinical sequels, notably neuropathic pain, foot ulcers, and autonomic dysfunction, is associated with substantial morbidity, increased risk of mortality, and reduced quality of life. Despite its major clinical impact, diabetic neuropathy remains underdiagnosed and undertreated. Moreover, the evidence supporting a benefit for causal treatment is weak at least in patients with type 2 diabetes, and current pharmacotherapy is largely limited to symptomatic treatment options. Thus, a better understanding of the underlying pathophysiology is mandatory for translation into new diagnostic and treatment approaches. Improved knowledge about pathogenic pathways implicated in the development of diabetic neuropathy could lead to novel diagnostic techniques that have the potential of improving the early detection of neuropathy in diabetes and prediabetes to eventually embark on new treatment strategies. In this review, we first provide an overview on the current clinical aspects and illustrate the pathogenetic concepts of (pre)diabetic neuropathy. We then describe the biomarkers emerging from these concepts and novel diagnostic tools and appraise their utility in the early detection and prediction of predominantly distal sensorimotor polyneuropathy. Finally, we discuss the evidence for and limitations of the current and novel therapy options with particular emphasis on lifestyle modification and pathogenesis-derived treatment approaches. Altogether, recent years have brought forth a multitude of emerging biomarkers reflecting different pathogenic pathways such as oxidative stress and inflammation and diagnostic tools for an early detection and prediction of (pre)diabetic neuropathy. Ultimately, these insights should culminate in improving our therapeutic armamentarium against this common and debilitating or even life-threatening condition.

A systematic review and meta-analysis of nutrition interventions for chronic noncancer pain

BACKGROUND

This systematic review aimed to evaluate the impact of nutrition interventions on participant reported pain severity and intensity in populations with chronic pain.

METHODS

Eight databases were systematically searched for studies that included adult populations with a chronic pain condition, a nutrition intervention and a measure of pain. Where possible, data were pooled using meta-analysis. Seventy-one studies were included, with 23 being eligible for meta-analysis.

RESULTS

Studies were categorised into four groups: (i) altered overall diet with 12 of 16 studies finding a significant reduction in participant reported pain; (ii) altered specific nutrients with two of five studies reporting a significant reduction in participant reported pain; (iii) supplement-based interventions with 11 of 46 studies showing a significant reduction in pain; and (iv) fasting therapy with one of four studies reporting a significant reduction in pain. The meta-analysis found that, overall, nutrition interventions had a significant effect on pain reduction with studies testing an altered overall diet or just one nutrient having the greatest effect.

CONCLUSIONS

This review highlights the importance and effectiveness of nutrition interventions for people who experience chronic pain.

The Necessity of the Simple Tests for Diabetic Peripheral Neuropathy in Type 2 Diabetes Mellitus Patients without Neuropathic Symptoms in Clinical Practice

Early recognition and appropriate management of diabetic peripheral polyneuropathy (DPNP) is important. We evaluated the necessity of simple, non-invasive tests for DPNP detection in clinical practice. We enrolled 136 randomly-chosen patients with type 2 diabetes mellitus and examined them with the 10-g Semmes-Weinstein monofilament examination, the 128-Hz tuning-fork, ankle-reflex, and pinprick tests; the Total Symptom Score and the 15-item self-administered questionnaire of the Michigan Neuropathy Screening Instrument. Among 136 patients, 48 had subjective neuropathic symptoms and 88 did not. The abnormal-response rates varied depending on the methods used according to the presence of subjective neuropathic symptoms (18.8% vs. 5.7%, P<0.05; 58.3% vs. 28.4%, P<0.005; 81.3% vs. 54.5%, P<0.005; 12.5% vs. 5.7%, P=0.195; 41.7% vs. 2.3%, P<0.001; and 77.1% vs. 9.1%, P<0.001; respectively). The largest abnormal response was derived by combining all methods. Moreover, these tests should be implemented more extensively in diabetic patients without neuropathic symptoms to detect DPNP early.

Alpha lipoic acid combined with epalrestat: a therapeutic option for patients with diabetic peripheral neuropathy

BACKGROUND

Alpha lipoic acid (ALA), a type of antioxidant, is used in combination with epalrestat in the treatment of diabetic peripheral neuropathy (DPN). However, whether combined treatment is superior to epalrestat monotherapy is controversial.

METHODS

We conducted a systematic search of PubMed, Cochrane Library and Chinese databases to identify all randomized controlled trials (RCTs) up to October 31, 2017. Data were extracted to evaluate methodological quality and analyzed using Review Manager 5.3.0 software.

RESULTS

Twelve studies were included. Compared to epalrestat monotherapy, ALA 600 mg/d once a day (qd) combined with epalrestat 50 mg three times a day (tid) augmented the total effectiveness rate (14 days - risk ratio [RR]: 1.40, 95% CI: 1.16-1.69, P=0.0005; 28 days - RR: 1.48, 95% CI: 1.27-1.72, P<0.00001); at the same, it could improve the median motor nerve conduction velocity (MNCV) and sensory nerve conduction velocity (SNCV), peroneal MNCV, and SNCV after 14, 21, and 28 days of treatment and could reduce the Toronto Clinical Scoring System (TCSS) (weighted mean difference [WMD]: -1.60, 95% CI: (-2.91, -0.29), P=0.02) and Total Symptom Score (TSS) (WMD: -0.93, 95% CI: -1.27, -0.60, P<0.00001) after 21 days of treatment. The treatment strategy of ALA 300 mg/d qd combined with epalrestat 50 mg tid had the same effects in regard to the total effectiveness rate (RR: 1.37, 95% CI: 1.18-1.59, P<0.0001), median MNCV (WMD: 6.12, 95% CI: 5.04, 7.20, P=0.00001), median SNCV (WMD: 6.70, 95% CI: 5.75, 7.65, P=0.00001), peroneal MNCV (WMD: 6.68, 95% CI: 5.82, 7.55, P=0.00001), and peroneal SNCV (WMD: 4.27, 95% CI: 3.34, 5.20, P=0.00001) after 28 days of treatment.

CONCLUSION

ALA combined with epalrestat is an effective option for DPN patients. Future large-sample RCTs should be conducted to further confirm this finding.

Peripheral Neuropathy as a Complication of Diabetic Ketoacidosis in a Child with Newly Diagnosed Diabetes Type 1: A Case Report

Neurological complications of diabetic ketoacidosis are considered to be a serious clinical problem. The most common complication is cerebral edema. However, these neurological complications also include less common entities such as ischemic or hemorrhagic stroke, cerebral venous and sinus thrombosis or peripheral neuropathy. We present a case of a 9-year old girl admitted to our intensive care unit with new onset type 1 diabetes, diabetic ketoacidosis, cerebral edema, multifocal vasogenic brain lesions and bilateral lower limb peripheral paresis. The patient developed polydipsia and polyuria one week before admission. The initial blood glucose level was 1136 mg/dL and severe acidosis was present (pH 7.1; BE-25.9). Computed tomography scan showed brain edema and a hypodense lesion in the left temporal region. Brain magnetic resonance imaging revealed more advanced multifocal brain lesions. Nerve conduction studies demonstrated damage of the motor neurons in both lower limbs with dysfunction in both peroneal nerves and the right tibial nerve. With treatment and physiotherapy, the patient’s health gradually improved. Acute neuropathy after ketoacidosis is a rare complication and its pathogenesis is not clear. Patients with diabetic ketoacidosis require careful monitoring of neurological function, even after normalization of their glycemic parameters.

R(+)-Thioctic Acid Effects on Oxidative Stress and Peripheral Neuropathy in Type II Diabetic Patients: Preliminary Results by Electron Paramagnetic Resonance and Electroneurography

Objectives

Diabetic neuropathy is the most common complication of diabetes. The idea of alterations in energy metabolism in diabetes is emerging. The biogenic antioxidant R(+)-thioctic acid has been successfully used in the treatment of diabetic polyneuropathic (DPN) patients.

Methods

The effects of R(+)-thioctic acid (1 tablet, 1.6 g) administration were evaluated in 12 DPN patients at baseline and at 15, 30, 60, and 120 administration days throughout the assessment of oxidative stress (OxS); ROS production rate by electron paramagnetic resonance (EPR) technique; and oxidative damage biomarkers (thiobarbituric acid reactive substances (TBARS) and protein carbonyls (PC)), electroneurography (ENG) and visual analogue scale.

Results

Supplementation induced significant changes (p < 0.05) at 30 and 60 days. ROS production rate up to -16%; TBARS (-31%), PC (-38%), and TAC up to +48%. Motor nerve conduction velocity in SPE and ulnar nerves (+22% and +16%) and sensor conduction velocity in sural and median nerves (+22% and +5%). Patients reported a general wellness sensation improvement (+35%) at 30 days: lower limb pain sensation (-40%) and upper limbs (-23%).

Conclusion

The results strongly indicate that an increased antioxidant capacity plays an important role in OxS, nerve conduction velocity, pain, and general wellness improvement. Nevertheless, the effects of the antioxidant compound were found positive up to 60 days. Then, a hormesis effect was observed. Novelty of the research would be a challenge for investigators to carefully address issues, including dose range factors, appropriate administration time, and targeting population to counteract possible "boomerang effects." The great number of monitored parameters would firmly stress these conclusions.

The Quest for more Research on Painful Diabetic Neuropathy

A 62-year-old diabetologist diagnosed himself to have diabetes type-2, with an HbA1c of 9.5. Five months after lifestyle intervention and a multi-drug approach, HbA1c was 6.3, systolic blood pressure was below 135mmHg and BMI reduced to 27. But he suffered from severe painful diabetic neuropathy. Therefore he decided to visit his friend, a famous neuroscientist at an even more famous university. He asked him several plain questions: 1. What is the natural course of painful diabetic neuropathy? 2. Why do I have, despite almost normalizing HbA1c, more problems than before? 3. Are you sure my problems are due to diabetes or should we do a nerve biopsy? 4. Are there imaging techniques helpful for the diagnosis of this diabetic complication, starting in the distal nerve endings of the foot and slowly moving ahead? 5. Can you suggest any drug, specific and effective, for relieving painful diabetic neuropathy? This review will use the experts' answers to the questions of the diabetologist, not only to give a summary of the current knowledge, but even more to highlight areas of research needed for improving the fate of patients with painful diabetic neuropathy. Based on the unknowns, which exceed the knowns in diabetic neuropathy, a quest for more public support of research is made.

Long-term stabilization of metastatic melanoma with sodium dichloroacetate

Sodium dichloroacetate (DCA) has been studied as a metabolic cancer therapy since 2007, based on a publication from Bonnet et al demonstrating that DCA can induce apoptosis (programmed cell death) in human breast, lung and brain cancer cells. Classically, the response of cancer to a medical therapy in human research is measured by Response Evaluation Criterial for Solid Tumours definitions, which define “response” by the degree of tumour reduction, or tumour disappearance on imaging, however disease stabilization is also a beneficial clinical outcome. It has been shown that DCA can function as a cytostatic agent in vitro and in vivo, without causing apoptosis. A case of a 32-year-old male is presented in which DCA therapy, with no concurrent conventional therapy, resulted in regression and stabilization of recurrent metastatic melanoma for over 4 years’ duration, with trivial side effects. This case demonstrates that DCA can be used to reduce disease volume and maintain long-term stability in patients with advanced melanoma.

Declining Skeletal Muscle Function in Diabetic Peripheral Neuropathy

PURPOSE

The present review highlights current concepts regarding the effects of diabetic peripheral neuropathy (DPN) in skeletal muscle. It discusses the lack of effective pharmacologic treatments and the role of physical exercise intervention in limb protection and symptom reversal. It also highlights the importance of magnetic resonance imaging (MRI) techniques in providing a mechanistic understanding of the disease and helping develop targeted treatments.

METHODS

This review provides a comprehensive reporting on the effects of DPN in the skeletal muscle of patients with diabetes. It also provides an update on the most recent trials of exercise intervention targeting DPN pathology. Lastly, we report on emerging MRI techniques that have shown promise in providing a mechanistic understanding of DPN and can help improve the design and implementation of clinical trials in the future.

FINDINGS

Impairments in lower limb muscles reduce functional capacity and contribute to altered gait, increased fall risk, and impaired balance in patients with DPN. This finding is an important concern for patients with DPN because their falls are likely to be injurious and lead to bone fractures, poorly healing wounds, and chronic infections that may require amputation. Preliminary studies have shown that moderate-intensity exercise programs are well tolerated by patients with DPN. They can improve their cardiorespiratory function and partially reverse some of the symptoms of DPN. MRI has the potential to bring new mechanistic insights into the effects of DPN as well as to objectively measure small changes in DPN pathology as a result of intervention.

IMPLICATIONS

Noninvasive exercise intervention is particularly valuable in DPN because of its safety, low cost, and potential to augment pharmacologic interventions. As we gain a better mechanistic understanding of the disease, more targeted and effective interventions can be designed.

[α-Lipoic acid as the main pharmacological drug for in- and outpatient treatment of diabetic polyneuropathy]

α-Lipoic acid, or thioctic acid, (ALA) is the most applicable pharmacological drug for treatment of diabetic polyneuropathy. The article explores the results of experimental studies on the α-lipoic acid effect on mechanisms of peripheral nerves affection in hyperglycemia as well as the data of numerous randomized controlled trials and meta-analyses on studying ALA efficacy in symptomatic diabetic polyneuropathy. It has been shown that amelioration of patients with diabetic polyneuropathy is observed both for ALA infusions and tableted form of the drug. The authors conclude that α-lipoic acid is a drug for treatment of pathogenetic development mechanisms of diabetic polyneuropathy with the best proven efficacy.

Innovations in the Management of Musculoskeletal Pain With Alpha-Lipoic Acid (IMPALA Trial): Study protocol for a Double-Blind, Randomized, Placebo-Controlled Crossover Trial of Alpha-Lipoic Acid for the Treatment of Fibromyalgia Pain

BACKGROUND

Fibromyalgia is a common disorder characterized by chronic widespread pain, sleep disturbance, fatigue, depression, and cognitive dysfunction, resulting in substantial disability. As current analgesics provide incomplete relief and disabling side effects that aggravate fatigue and cognitive dysfunction, there is a need for new pain treatments with better efficacy and tolerability. Alpha-lipoic acid (ALA) is an antioxidant proven effective in painful diabetic neuropathy with minimal side effects.

OBJECTIVE

We hypothesize that this agent will provide benefits in fibromyalgia because of several similarities with neuropathic pain and also because it does not cause sedation, fatigue, or mental-slowing. To test this, we have designed a clinical trial that will assess pain, side effects, and other outcomes in participants with fibromyalgia.

METHODS

Using a crossover design, 24 adults with fibromyalgia will be randomly allocated to 1 of the 2 sequences of ALA and placebo. Participants will take capsules containing ALA or placebo for 4 weeks followed by a 1-week washout followed by a second 4-week treatment and 1-week washout period. ALA (or matching placebo) capsules will be titrated to 1800 mg/day over each 4-week period. The primary outcome will be mean daily pain intensity (0-10) during week 4 of each period. Secondary outcomes, assessed during week 4 of each period, will include global improvement, adverse events, mood, and quality of life.

RESULTS

This trial was registered in the International Standard Randomized Controlled Trial registry March 15, 2016 (Number ISRCTN58259979), and it attained ethics approval on December 3, 2016 (Queen's University Health Sciences & Affiliated Teaching Hospitals Research Ethics Board protocol number ANAE-287-15). The recruitment started in February 2017.

CONCLUSIONS

This trial will provide evidence for the efficacy of ALA in fibromyalgia.

TRIAL REGISTRATION

International Standard Randomized Controlled Trial Number (ISRCTN): 58259979; www.isrctn.com/ISRCTN58259979 (Archived by WebCite at http://www.webcitation.org/6og9JdiyZ).

Nutraceuticals against Neurodegeneration: A Mechanistic Insight

The mechanisms underlying neurodegenerative disorders are complex and multifactorial; however, accumulating evidences suggest few common shared pathways. These common pathways include mitochondrial dysfunction, intracellular Ca²⁺ overload, oxidative stress and inflammation. Often multiple pathways co-exist, and therefore limit the benefits of therapeutic interventions. Nutraceuticals have recently gained importance owing to their multifaceted effects. These food-based approaches are believed to target multiple pathways in a slow but more physiological manner without causing severe adverse effects. Available information strongly supports the notion that apart from preventing the onset of neuronal damage, nutraceuticals can potentially attenuate the continued progression of neuronal destruction. In this article, we i) review the common pathways involved in the pathogenesis of the toxicants-induced neurotoxicity and neurodegenerative disorders with special emphasis on Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), Multiple sclerosis (MS) and Amyotrophic lateral sclerosis (ALS), and ii) summarize current research advancements on the effects of nutraceuticals against these detrimental pathways.

Systematic review of treatments for diabetic peripheral neuropathy

AIM

To evaluate treatment options for neuropathic pain and sensory symptoms resulting from diabetic peripheral neuropathy of the feet.

METHODS

The databases PubMed, Embase and Web-of-Science were searched for randomized controlled trials, published in the period from database inception to 2 July 2015, that evaluated treatments for diabetic peripheral neuropathy of the feet with placebo or standard treatment as comparators. Participants in these trials included people with diabetes mellitus and diabetic peripheral neuropathy who were given any treatment for diabetic peripheral neuropathy. Risk of bias was assessed using the Delphi list of criteria. Data from the trials were extracted using standardized data extraction sheets by two authors independently. All analyses were performed using RevMan 5.2. In case of clinical homogeneity, statistical pooling was performed using a random effects model.

RESULTS

This review included 27 trials on pharmacological, non-pharmacological and alternative treatments. In the meta-analysis of trials of α-lipoic acid versus placebo, total symptom score was reduced by -2.45 (95% CI -4.52; -0.39) with 600 mg i.v. α-lipoic acid (three trials), and was reduced by -1.95 (95% CI -2.89; -1.01) with 600 mg oral α-lipoic acid (two trials). Significant improvements in diabetic peripheral neuropathy symptoms were found with opioids, botulinum toxin A, mexidol, reflexology and Thai foot massage, but not with micronutrients, neurotrophic peptide ORG 2677 and photon stimulation therapy.

CONCLUSION

In this review, we found that α-lipoic acid, opioids, botulinum toxin A, mexidol, reflexology and Thai foot massage had significant beneficial results.

Long-term stabilization of stage 4 colon cancer using sodium dichloroacetate therapy

Oral dichloroacetate sodium (DCA) has been investigated as a novel metabolic therapy for various cancers since 2007, based on data from Bonnet et al that DCA can trigger apoptosis of human lung, breast and brain cancer cells. Response to therapy in human studies is measured by standard RECIST definitions, which define “response” by the degree of tumour reduction, or tumour disappearance on imaging. However, Blackburn et al have demonstrated that DCA can also act as a cytostatic agent in vitro and in vivo, without causing apoptosis (programmed cell death). A case is presented in which oral DCA therapy resulted in tumour stabilization of stage 4 colon cancer in a 57 years old female for a period of nearly 4 years, with no serious toxicity. Since the natural history of stage 4 colon cancer consists of steady progression leading to disability and death, this case highlights a novel use of DCA as a cytostatic agent with a potential to maintain long-term stability of advanced-stage cancer.

Neuropathic Pain Treatment: Still a Challenge

Neuropathic pain (NP) is the result of a series of conditions caused by diseases or lesions to the somatosensory system. Due to the better understanding of NP pathophysiology previously unexplored therapies have been used with encouraging results. In this group, acetyl-L-carnitine, alpha-lipoic-acid, cannabinoids, clonidine, EMA401, botulinum toxin type A and new voltage-gated sodium channel blockers, can be included. Besides, changing paradigms may occur with the advent of optogenetics and a better understanding of epigenetic regulation. We reviewed the published literature on the pharmacological treatment of NP. Despite the interesting results, randomized controlled trials are demanded the majority of the therapies previously mentioned. In spite of several studies for the relief of NP, pain control continues being a challenge.

Altered glutathione system is associated with the presence of distal symmetric peripheral polyneuropathy in type 2 diabetic subjects

Distal symmetric peripheral polyneuropathy (DSPN) is a highly prevalent complication of diabetes. However, underlying pathophysiological mechanisms are multiple and not well understood. The aim of our study was to analyze the oxidative stress levels in circulating mononuclear cells by measuring the glutathione system, malondialdehyde and oxidized-LDL, in 60 type 2 diabetic patients from a well-characterized cohort of 196 type 2 diabetic patients. Using a nested case-control design, we studied 30 type 2 diabetic patients with distal symmetric polyneuropathy and 30 diabetic controls without this complication, according to the Neuropathy Disability Score. We have found that diabetic patients with distal symmetric polyneuropathy showed significantly lower values of reduced glutathione (GSH) and reduced glutathione/oxidized glutathione (GSH/GSSG) ratio. These data indicate an increased consumption of glutathione in mononuclear cells from patients with distal symmetric polyneuropathy. No significant differences were found in malondialdehyde or in oxidized-LDL levels comparing both groups. These data show an altered glutathione response in circulating monocytes from diabetic patients with distal symmetric polyneuropathy.

The New Age of Sudomotor Function Testing: A Sensitive and Specific Biomarker for Diagnosis, Estimation of Severity, Monitoring Progression, and Regression in Response to Intervention

Sudorimetry technology has evolved dramatically, as a rapid, non-invasive, robust, and accurate biomarker for small fibers that can easily be integrated into clinical practice. Though skin biopsy with quantitation of intraepidermal nerve fiber density is still currently recognized as the gold standard, sudorimetry may yield diagnostic information not only on autonomic dysfunction but also enhance the assessment of the small somatosensory nerves, disease detection, progression, and response to therapy. Sudorimetry can be assessed using Sudoscan™, which measures electrochemical skin conductance (ESC) of hands and feet. It is based on different electrochemical principles (reverse iontophoresis and chronoamperometry) to measure sudomotor function than prior technologies, affording it a much more practical and precise performance profile for routine clinical use with potential as a research tool. Small nerve fiber dysfunction has been found to occur early in metabolic syndrome and diabetes and may also be the only neurological manifestation in small fiber neuropathies, beneath the detection limits of traditional nerve function tests. Test results are robust, accomplished within minutes, require little technical training and no calculations, since established norms have been provided for the effects of age, gender, and ethnicity. Sudomotor testing has been greatly under-utilized in the past, restricted to specialized centers capable of handling the technically demanding and expensive technology. Yet, evaluation of autonomic and somatic nerve function has been shown to be one of the best estimates of cardiovascular risk. Evaluation of sweating has the appeal of quantifiable non-invasive determination of the integrity of the peripheral autonomic nervous system, and can now be accomplished rapidly at point of care clinics with the determination of ESC, allowing intervention for morbid complications prior to permanent structural nerve damage. We review here sudomotor function testing technology, the research evidence accumulated supporting the clinical utility of measuring ESC, the medical applications of sudorimetry now available to physicians with this device, and clinical vignettes illustrating its use in the clinical decision-making process.

Pathways in the diagnosis and management of diabetic polyneuropathy

Distal symmetric polyneuropathy (DSPN), the most common form of diabetic neuropathy, has a complex pathophysiology and can be a major source of physical and psychologic disability. The management of DSPN can be frustrating for both patient and physician. This article provides a general overview of typical patient pathways in DSPN, and highlights variations in diagnosis, management, and referral patterns among different providers. DSPN is managed in several settings by primary care physicians (PCPs), specialists, and nurse practitioners. The initial clinical management of the patient is often dependent on the presenting complaint, the referral pattern of the provider, level of comfort of the PCP in managing diabetic complications, and geographic access to specialists. The primary treatment of DSPN focuses mainly on glycemic control and adjustment of modifiable risk factors, but other causes of neuropathy should also be investigated. Several pharmacologic agents are recommended by treatment guidelines, and as DSPN typically exists with comorbid conditions, a multimodal therapeutic approach should be considered. Barriers to effective management include failure to recognize DSPN, and misdiagnosis. Patient education also remains important. Referral patterns vary widely according to geographic location, access to services, provider preferences, and comfort in managing complex aspects of the disease. The variability in patient pathways affects patient education, satisfaction, and outcomes. Standardized screening tools, a multidisciplinary team approach, and treatment algorithms for diabetic neuropathy should improve future care. To improve patient outcomes, DSPN needs to be diagnosed sooner and interventions made before significant nerve damage occurs.

The effect of thioctic acid on allodynia in a rat vincristine-induced neuropathy model

Objective

To investigate the antiallodynic effects of thioctic acid in vincristine-induced neuropathy in rats.

Methods

Neuropathy was induced in Sprague–Dawley rats via vincristine intraperitoneal injection. After 15 days, rats were investigated for the presence of mechanical and cold allodynia, and those with allodynia received intraperitoneal injection with normal saline or 1, 5, or 10 mg/kg thioctic acid. Mechanical and cold allodynia were assessed before treatment and at 15, 30, 60, 90, 150 and 180 min after treatment.

Results

Mechanical and cold allodynia were reduced by thioctic acid injection. The duration of effect increased with thioctic acid dose.

Conclusion

Thioctic acid may be an effective treatment for vincristine-induced neuropathy.

Treatment with α-Lipoic Acid over 16 Weeks in Type 2 Diabetic Patients with Symptomatic Polyneuropathy Who Responded to Initial 4-Week High-Dose Loading

Effective treatment of diabetic sensorimotor polyneuropathy remains a challenge. To assess the efficacy and safety of α-lipoic acid (ALA) over 20 weeks, we conducted a multicenter randomized withdrawal open-label study, in which 45 patients with type 2 diabetes and symptomatic polyneuropathy were initially treated with ALA (600 mg tid) for 4 weeks (phase 1). Subsequently, responders were randomized to receive ALA (600 mg qd; n = 16) or to ALA withdrawal (n = 17) for 16 weeks (phase 2). During phase 1, the Total Symptom Score (TSS) decreased from 8.9 ± 1.8 points to 3.46 ± 2.0 points. During phase 2, TSS improved from 3.7 ± 1.9 points to 2.5 ± 2.5 points in the ALA treated group (p < 0.05) and remained unchanged in the ALA withdrawal group. The use of analgesic rescue medication was higher in the ALA withdrawal group than ALA treated group (p < 0.05). In conclusion, in type 2 diabetic patients with symptomatic polyneuropathy who responded to initial 4-week high-dose (600 mg tid) administration of ALA, subsequent treatment with ALA (600 mg qd) over 16 weeks improved neuropathic symptoms, whereas ALA withdrawal was associated with a higher use of rescue analgesic drugs. This trial is registered with ClinicalTrials.gov Identifier: NCT02439879.

Efficacy of α-lipoic acid in diabetic neuropathy

INTRODUCTION

Neuropathy is a serious complication of diabetes. Its management focuses on glycaemic control, multifactorial cardiovascular risk intervention, pathogenesis-oriented therapy, and analgesics where needed.

AREAS COVERED

The objective of this review is assessment of efficacy and safety of α lipoic acid (ALA, also thioctic acid) in pathogenesis-oriented treatment of diabetic neuropathy. The mechanisms of action of ALA in experimental diabetic neuropathy include reduction of oxidative stress along with improvement in nerve blood flow, nerve conduction velocity, and several other measures of nerve function. There is ample evidence from randomised, double-blind, placebo-controlled clinical trials and meta-analyses, suggesting that ALA is efficacious and safe for the diabetic neuropathy, accomplishing clinically meaningful improvements.

EXPERT OPINION

ALA is a valuable therapeutic option for diabetic neuropathy. When compared with currently licensed analgesic drugs, it is better tolerated, has a more rapid onset of action, and improves paraesthesiae, numbness, sensory deficits, and muscle strength in addition to neuropathic pain. In clinical practice, ALA may be chosen in patients with early neuropathic deficits and symptoms, in whom clinical improvement is more likely. ALA should also be considered when comorbidities render other analgesics less appropriate or in the presence of cardiovascular autonomic neuropathy.

Promising treatments for neuropathic pain

In the last few years the understanding of mechanisms and, consequently, the diagnosis of neuropathic pain (NP) has becoming progressively clearer in clinical practice. However, the treatment of such condition remains challenging so far. One of the reasons for such difficulty is the diversity of mechanisms involved in NP generation and its persistency. In the present review we discuss several treatment modalities for NP that are scantily applied in daily clinical practice. For that, we collected positive clinical evidence of unusual and SECS (Safe, Easy, Cheap, and Sensible) approaches for NP. The aim of this review is not to establish the “state of the art” or rigid guidelines for NP treatment. In a different way, we only want bring new possibilities of treatment to the readers and also to motivate investigators to confirm those positive preliminary but promising results for NP reliev.

Evaluating the Phase II drugs currently under investigation for diabetic neuropathy

Introduction: The worldwide number of patients suffering from diabetes mellitus (DM) is projected to approach 552 million by the year 2030. As diabetic neuropathy (DN) is present in 8% of new diabetic patients at the time of diagnosis and occurs in ∼ 50% of all patients with established DM, the number of patients who will develop painful DN will also increase. The suboptimal efficacies of currently approved drugs have prompted investigators to develop new therapeutic agents for the management of painful DN. Areas covered: In this review, the authors present and elucidate the current status of drugs under investigation for the treatment of painful DN. A short synopsis of currently approved drugs is also given. Literature information and data analysis were retrieved from PubMed, the American Diabetes and Neurological Associations Websites and ClinicalTrials.gov. The keywords used in the search included: DM, DN, painful diabetic neuropathy. Expert opinion: In addition to treating the pain associated with DN, the actual causes of the disease should also be targeted for improved management. It is hoped that drugs which improve vascular blood flow, induce neural regeneration, reduce hyperglycemia, oxidative stress and inflammation can be more effective for the overall treatment of painful DN.

Alpha-lipoic acid as a pleiotropic compound with potential therapeutic use in diabetes and other chronic diseases

Alpha-lipoic acid is a naturally occurring substance, essential for the function of different enzymes that take part in mitochondria's oxidative metabolism. It is believed that alpha-lipoic acid or its reduced form, dihydrolipoic acid have many biochemical functions acting as biological antioxidants, as metal chelators, reducers of the oxidized forms of other antioxidant agents such as vitamin C and E, and modulator of the signaling transduction of several pathways. These above-mentioned actions have been shown in experimental studies emphasizing the use of alpha-lipoic acid as a potential therapeutic agent for many chronic diseases with great epidemiological as well economic and social impact such as brain diseases and cognitive dysfunctions like Alzheimer disease, obesity, nonalcoholic fatty liver disease, burning mouth syndrome, cardiovascular disease, hypertension, some types of cancer, glaucoma and osteoporosis. Many conflicting data have been found concerning the clinical use of alpha-lipoic acid in the treatment of diabetes and of diabetes-related chronic complications such as retinopathy, nephropathy, neuropathy, wound healing and diabetic cardiovascular autonomic neuropathy. The most frequent clinical condition in which alpha-lipoic acid has been studied was in the management of diabetic peripheral neuropathy in patients with type 1 as well type 2 diabetes. Considering that oxidative stress, a imbalance between pro and antioxidants with excessive production of reactive oxygen species, is a factor in the development of many diseases and that alpha-lipoic acid, a natural thiol antioxidant, has been shown to have beneficial effects on oxidative stress parameters in various tissues we wrote this article in order to make an up-to-date review of current thinking regarding alpha-lipoic acid and its use as an antioxidant drug therapy for a myriad of diseases that could have potential benefits from its use.

Chronic pain epidemiology - where do lifestyle factors fit in?

Chronic pain is common and complex and has a large impact on individuals and society. Good epidemiological pain data provide key information on the use of resources (both in general practice and in specialist clinics), insight into factors that lead to or favour chronicity and the design of interventions aimed at reducing or preventing the effects of chronic pain. This review aims to highlight the important factors associated with chronic pain, including those factors which are amenable to lifestyle intervention.

Whither pathogenetic treatments for diabetic polyneuropathy?

Diabetic distal symmetric polyneuropathy (DSPN) occurs in around one-third of patients with diabetes and is associated with significant morbidity and increased mortality. Diagnosis and clinical assessment of DSPN remain a challenge, not only for the physician in clinical practice but also for clinical trials. Optimal diabetes control is generally considered an essential first step in the prevention and management of DSPN. However, glycaemic control alone may be insufficient to prevent the development or progression of DSPN, especially in type 2 diabetes. Near-normoglycaemia is also difficult to achieve in a significant proportion of patients. Although considerable advances have been made in symptomatic pain management, these have not addressed the problem of sensory deficits and have no impact on the underlying pathogenesis of DSPN. There remains a lack of treatment options that effectively target the natural history of the disease. Several pathogenetic treatment approaches have been investigated, but evidence from clinical trials is limited with a number of treatments having shown disappointing results. However, some pathogenetic therapies have shown clinically relevant improvements in neuropathic endpoints in randomised controlled trials, in particular α-lipoic acid and Actovegin. These advances in DSPN disease modification need to be confirmed with further robust evidence from clinical trials together with a better understanding of the mechanisms of action of promising treatments.

Direct and indirect antioxidant properties of α-lipoic acid and therapeutic potential

Diabetes has emerged as a major threat to worldwide health. The exact mechanisms underlying the disease are unknown; however, there is growing evidence that the excess generation of reactive oxygen species (ROS) associated with hyperglycemia, causes oxidative stress in a variety of tissues. In this context, various natural compounds with pleiotropic actions like α-lipoic acid (LA) are of interest, especially in metabolic diseases such as diabetes. LA, either as a dietary supplement or a therapeutic agent, modulates redox potential because of its ability to match the redox status between different subcellular compartments as well as extracellularly. Both the oxidized (disulfide) and reduced (di-thiol: dihydro-lipoic acid, DHLA) forms of LA show antioxidant properties. LA exerts antioxidant effects in biological systems through ROS quenching but also via an action on transition metal chelation. Dietary supplementation with LA has been successfully employed in a variety of in vivo models of disease associated with an imbalance of redox status: diabetes and cardiovascular diseases. The complex and intimate association between increased oxidative stress and increased inflammation in related disorders such as diabetes, makes it difficult to establish the temporal sequence of the relationship.

Lipoic Acid prevents the changes of intracellular lipid partitioning by free Fatty Acid

Background/Aims

It is suggested that the hepatic lipid composition is more important than lipid quantity in the pathogenesis of non-alcoholic steatohepatitis. We examined whether lipoic acid (LA) could alter intrahepatic lipid composition and free cholesterol distribution.

Methods

HepG2 cells were cultured with palmitic acid (PA) with and without LA. Apoptosis, changes of the mitochondrial structure, intracellular lipid partitioning, and reactive oxygen species (ROS) activity were measured.

Results

Free fatty acid (FA) increased apoptosis, and LA co-treatment prevented this lipotoxicity (apoptosis in controls vs PA vs PA+LA, 0.5% vs 19.5% vs 1.6%, p<0.05). LA also restored the intracellular mitochondrial DNA copy number (553±33.8 copies vs 291±14.55 copies vs 421±21.05 copies, p<0.05) and reversed the morphological changes induced by PA. In addition, ROS was increased in response to PA and was decreased in response to LA co-treatment (41,382 relative fluorescence unit [RFU] vs 43,646 RFU vs 41,935 RFU, p<0.05). LA co-treatment increased the monounsaturated and polyunsaturated FA concentrations and decreased the total saturated FA fraction. It also prevented the movement of intracellular free cholesterol from the cell membrane to the cytoplasm.

Conclusions

LA opposes free FA-generated lipotoxicity by altering the intracellular lipid composition and free cholesterol distribution.

Diabetic neuropathies: diagnosis and management

INTRODUCTION

Changes in human behaviour and lifestyle over the last century have resulted in a dramatic increase in the incidence of diabetes worldwide. Neuropathy is a common and costly complication of both type 1 and type 2 diabetes. The prevalence of neuropathy is estimated to be about 8% in newly diagnosed patients and greater than 50% in patients with long-standing disease. There are two main types of diabetic neuropathies, named as sensorimotor and autonomic neuropathies. Sensorimotor neuropathy is marked by pain, paraesthesia and sensory loss, and autonomic neuropathy may contribute to myocardial infarction, malignant arrhythmia and sudden death.

METHODS

In this article we reviewed the pathogenesis, clinical manifestations diagnosis and treatment of diabetic neuropathies.

CONCLUSION

Sensorimotor and autonomic neuropathies (cardiovascular, gastrointestinal and genitourinary autonomic neuropathies) are common in diabetic patients. Apart from strict glycaemic control, no further therapeutic approach exists in the prevention of this phenomenon. Intensive diabetes therapy, intensive multifactorial cardiovascular risk reduction and lifestyle intervention are recommended in patients with cardiovascular autonomic neuropathy. Gastroparesis is the most debilitating complication of gastrointestinal autonomic neuropathy and genitourinary autonomic neuropathy can cause sexual dysfunction and neurogenic bladder; these conditions are hard to manage. The symptomatic treatment of sensory symptoms includes tricyclic antidepressants, serotonin and norepinephrine reuptake inhibitors, gabapentin, pregabalin and opioids. Other treatment strategies are not so effective.