The diabetic neuropathies: types, diagnosis and management

Development of a near infrared region based non-invasive therapy device for diabetic peripheral neuropathy

Diabetic Peripheral Neuropathy (DPN) is a nerve damage that is treated with painkillers and steroids which have the drawback of interference with other medications and the dangers of side effects. Novelty of the proposed work is to develop a Near Infrared Region (NIR) based non-invasive therapy device called 'DPNrelief-1.0V'developed with a 890 nm wavelength diodes. DPNrelief-1.0V delivers a total dosage of 6.174 J/cm2 with heat absorption by tissue of 61.74 Joules at 30 minutes. The device was tested by carrying out a pilot study with 8 patients where 4 were treatment group and control group. The DPNrelief-1.0V is validated by Nerve Conduction Study (NCS) test. The degenerated nerves pre-therapy showed less amplitude, Conduction Velocity (CV) and latency which was improved post-therapy by 100% in amplitude of nerve signal, 100% in CV and a decrease of 36.2% in latency. Independent t-test was conducted to find the difference between control and treatment, wherein a p value < 0.05 was obtained depicting significant difference between two groups. Furthermore, the performance of the device is validated by one-way test repeated measures Analysis of Variance (ANOVA), wherein a p value of < 0.05 was obtained depicting a difference in nerve condition pre-and post-therapy. The performance of DPNrelief-1.0V has outperformed Anodyne therapy device with lesser dosage, treatment time and portability and in curing the symptoms of DPN. DPNrelief-1.0V finds its potential in the field of medicine for treating DPN.

Posterior Tibial Nerve Ultrasound Assessment of Peripheral Neuropathy in Adults with Type 2 Diabetes Mellitus

Background

Diabetic peripheral neuropathy (DPN) is a common and debilitating complication of type 2 diabetes mellitus (T2DM). Early detection and prompt institution of appropriate therapy could prevent undesirable outcomes such as paresthesia, pain, and amputation. Although the gold standard for diagnosing DPN is nerve conduction studies, high-resolution peripheral nerve ultrasonography may serve as a noninvasive and low-cost alternative for diagnosing and staging DPN. This study investigated the clinical utility of sonographic posterior tibial nerve cross-sectional area (PTN CSA) for diagnosing DPN in individuals with T2DM.

Methods

Eighty consecutive adults with T2DM and 80 age-/sex-matched controls were recruited. Clinical information was obtained, including symptoms, disease duration, Toronto clinical neuropathy score (TCNS), and biochemical parameters. The left PTN CSA at 1 cm, 3 cm, and 5 cm above the medial malleolus (MM) was measured with a high-frequency ultrasound transducer and compared to the detection of DPN using the TCNS.

Results

Based on the TCNS, 58 (72.5%) of the T2DM group had DPN. Of these, 14 (24.1%), 16 (27.6%), and 28 (48.3%) participants had mild, moderate, and severe DPN, respectively. All the mean PTN CSA (aggregate, 1 cm, 3 cm, and 5 cm above MM) of the participants with T2DM and DPN (T2DM-DPN) were significantly higher than those of T2DM without DPN (WDPN) and controls. All the PTN CSA increased significantly with increasing severity of DPN. The PTN CSA at 3 and 5 cm levels correlated weakly but significantly with fasting plasma glucose and glycated hemoglobin levels.

Conclusion

The PTN CSA is significantly larger in T2DM-DPN than in T2DM-WDPN and healthy controls. PTN ultrasonography can be an additional tool for screening DPN in patients with T2DM.

Blink Reflex Examination in Patients with Amyotrophic Lateral Sclerosis Compared to Diseases Affecting the Peripheral Nervous System and Healthy Controls

Amyotrophic lateral sclerosis (ALS) is a fatal form of neuromuscular disease. The aim of this study was to assess changes in the blink reflex (BR) parameters as a valid and easy-to-use tool in ALS patients. We assessed the BR test in patients with a definitive diagnosis of ALS, healthy volunteers, and patients with diseases affecting the peripheral nervous system. The BR was studied in 29 patients who met the Awaji criteria. Latencies were compared with our healthy controls (N = 50) and other diseases of the peripheral nervous system (N = 61). The ALS Functional Rating Scale-Revised (ALSFRS-R) was used to evaluate functional status. Significantly prolonged R2i and R2c latencies were found in the ALS group compared with the healthy control group (p < 0.001). The latencies of R1, R2i, R2c were all increased in the bulbar subtype compared to the limb-onset subtype (p < 0.05). According to our results, BR examination might be a promising tool to monitor the course of the disease or serve as a prognostic biomarker in patients with ALS, but it should be assessed in further studies. The abnormalities detected through BR might help perform earlier interventions in ALS patients and might be useful in other diseases affecting the peripheral nervous system.

Role of High-resolution Ultrasonography in the Evaluation of the Tibial and Median Nerves in Diabetic Peripheral Neuropathy

AIM

To evaluate and measure the mean cross-sectional area of the tibial and median nerves in patients with diabetic peripheral neuropathy, and to study the association between high-resolution ultrasonographic findings in diabetic peripheral neuropathy with the duration of illness, glycosylated haemoglobin values, random blood sugar levels, and aesthesiometry (using monofilament examination).

MATERIAL AND METHODS

A prospective observational study was conducted among 63 patients who were diagnosed with type 2 diabetes mellitus and underwent ultrasound and monofilament examinations. The cross-sectional area of the median nerve of the dominant hand and the tibial nerves was calculated on ultrasound examination.

RESULTS

The mean cross-sectional area of the median and tibial nerves was higher in patients with poor glycaemic control, with the mean cross-sectional area of the median nerve being 10.9, 12.8, 13.0, and 12.9 mm² at various points in the leg in cases where the monofilament examination was negative, as compared to 7.30, 7.78, 7.91, 7.87 mm² in patients with positive monofilament examination results. There was a significant positive correlation between the cross-sectional area of the tibial and median nerves and HbA_1c, duration of diabetes, aesthesiometry, and random blood sugar levels. With an increase in HbA_1c, duration of diabetes, and random blood sugar levels, there was a corresponding increase in the cross-sectional area of the nerves. These findings helped us to identify diabetic peripheral neuropathy.

CONCLUSIONS

High-resolution ultrasonography along with aesthesiometry and HbA_1c values can be an effective and easily available tool for detecting changes secondary to diabetic peripheral neuropathy. The method has a potential to replace or substitute nerve conduction tests in the near future.

Molecular Insights on the Therapeutic Effect of Selected Flavonoids on Diabetic Neuropathy

One of the common clinical complications of diabetes is diabetic neuropathy affecting the nervous system. Painful diabetic neuropathy is widespread and highly prevalent. At least 50% of diabetes patients develop diabetic neuropathy eventually. The four main types of diabetic neuropathy are peripheral neuropathy, autonomic neuropathy, proximal neuropathy (diabetic polyradiculopathy), and mononeuropathy (Focal neuropathy). Glucose control remains the common therapy for diabetic neuropathy due to limited knowledge on early biomarkers that are expressed during nerve damage, thereby limiting the cure through pharmacotherapy. Glucose control dramatically reduces the onset of neuropathy in type 1 diabetes but proves less effective in type 2 diabetes. Therefore, the focus is on various herbal remedies for prevention and treatment. There is numerous research on the use of anticonvulsants and antidepressants for the management of pain in diabetic neuropathy. Extensive research is being done on natural products including the isolation of pure compounds like flavonoids from plants and their effect on diabetic neuropathy. This review focuses on the use of an important of flavonoids such as flavanols (e.g., quercetin, rutin, kaempferol, and isorhamnetin), flavanones (e.g., hesperidin, naringenin and c,lass eriodictyol), and flavones (e.g., apigenin, luteolin, tangeretin, chrysin, and diosmin) for the prevention and treatment of diabetic neuropathy. The mechanisms of action of flavonoids against diabetic neuropathy by their antioxidant, anti-inflammation, anti-glycation properties, etc. are also covered in this review article.

Diabetic neuropathy: an insight on the transition from synthetic drugs to herbal therapies

The global pandemic of prediabetes and diabetes has led to a severe corresponding complication of these disorders. Neuropathy is one of the most prevalent complication of diabetes is, affecting blood supply of the peripheral nervous system that may eventually results into loss of sensations, injuries, diabetic foot and death. The utmost identified risk of diabetic neuropathy is uncontrolled high blood glucose levels. However, aging, body mass index (BMI), oxidative stress, inflammation, increased HbA1c levels and blood pressure are among the other key factors involved in the upsurge of this disease. The so far treatment to deal with diabetic neuropathy is controlling metabolic glucose levels. Apart from this, drugs like reactive oxygen species (ROS) inhibitors, aldose reductase inhibitors, PKC inhibitors, Serotonin-norepinephrine reuptake inhibitors (SNRIs), anticonvulsants, N-methyl-D-aspartate receptor (NMDAR) antagonists, are the other prescribed medications. However, the related side-effects (hallucinations, drowsiness, memory deficits), cost, poor pharmacokinetics and drug resistance brought the trust of patients down and thus herbal renaissance is occurring all over the word as the people have shifted their intentions from synthetic drugs to herbal remedies. Medicinal plants have widely been utilized as herbal remedies against number of ailments in Indian medicinal history. Their bioactive components are very much potent to handle different chronic disorders and complications with lesser-known side effects. Therefore, the current article mainly concludes the etiology and pathophysiology of diabetic neuropathy. Furthermore, it also highlights the important roles of medicinal plants and their naturally occurring bioactive compounds in addressing this disease.

Adjuvant use of melatonin for relieving symptoms of painful diabetic neuropathy: results of a randomized, double-blinded, controlled trial

PURPOSE

The trial aimed to investigate the effectiveness of exogenous melatonin as an adjuvant to pregabalin for relief of pain in patients suffering from painful diabetic neuropathy (PDN).

PATIENTS AND METHODS

This randomized, double-blind, placebo-controlled trial was carried out between October 2019 and December 2020 in an outpatient specialty clinic in Iran. One-hundred-three type 2 diabetic patients suffering from PDN were randomized into either the melatonin group (n = 52) or the placebo group (n = 51). Besides pregabalin at a dose of 150 mg per day, patients started with melatonin or an identical placebo, at a dose of 3 mg/day at bedtime for 1 week, which was augmented to 6 mg/day for further 7 weeks. The primary outcomes were changes in mean NRS (numerical rating scale) pain score from baseline to endpoint and responder rate (patients with a reduction of 50% and higher in average pain score compared with baseline). Secondary endpoints were changes in mean NRS pain-related sleep-interference score, overall improvement evaluated by Patient and Clinical Global Impressions of Change (PGIC, CGIC), and impact of the intervention on patient's Health-related quality of life (QOL). All analyses were conducted on an Intention-to-Treat (ITT) analysis data set.

RESULTS

At the study endpoint, treatment with melatonin resulted in a considerably higher reduction in the mean NRS pain score in comparison with placebo (4.2 ± 1.83 vs. 2.9 ± 1.56; P-value < 0.001). In terms of treatment responders, a greater proportion of melatonin-treated patients satisfied the responder criterion than placebo-treated patients (63.5% vs. 43.1%). Melatonin also reduced pain-related sleep interference scores more than did placebo (3.38 ± 1.49 vs. 2.25 ± 1.26; P-value < 0.001). Further, at the endpoint, more improvement was also seen in terms of PGIC, CGIC, and Health-related QOL in patients treated with melatonin than placebo. Melatonin was also well tolerated.

CONCLUSION

The present results showed that melatonin as an adjunct therapy to pregabalin might be helpful for use in patients with PDN. However, confirmation of these results requires further studies.

Prevalence of diabetic peripheral neuropathy among type II diabetic patients in King Fahd University Hospital, Khobar, Kingdom of Saudi Arabia

Background: Diabetic peripheral neuropathies (DPN) are a common complication of diabetes mellitus (DM). DPN can be either painless or painful.General objective: To determine the prevalence of DPN among DM type II patients at King Fahd University Hospital (KFUH), Al-Khobar, Kingdom of Saudi Arabia (KSA).Specific objectives: To see the association between the prevalence of DPN and patient demographics and body mass index (BMI).To assess the relationship between the prevalence of DPN and DM type II and duration of disease.To provide awareness and education of DPN by pamphlets to the recruited diabetic patients at KFUH, Al-Khobar, KSA.Methods: questionnaire-based cross-sectional study, recruited DM type II patients from the internal medicine outpatient clinics at KFUH, Khobar, KSA. The investigators recorded patients' demographics (age, sex, and nationality), height, weight, and BMI, diabetes duration in years and laboratory results of fasting blood glucose (FBG), Hemoglobin A1C and the Michigan Neuropathy Screening Instrument (MNSI) has been applied.Results: among 187 recruited patients with type II DM, the prevalence of DPN was 37.4%. The mean age range of the sample was 56.4 ± 11.2 years. Females to males were 62.6% vs 37.4%. Saudis represented a great proportion of the participants constituting nearly 95.2%. The mean BMI of patients was 33.6 ± 7.08 kg/m². The mean FBG was 161.4 ± 62.9 mg/dL while the mean value of HbA1c was 8.11%±1.63%. HbA1c levels were significantly associated with DPN. Duration of DM of more than 1 year and FBG levels were significant predictors for patients to have DPN. Other socio-demographic variables such as age, gender, nationality, and BMI levels were not significantly associated with DPN.Conclusion: DPN affects 37.4% of type II diabetic patients at King Fahd University Hospital in Saudi Arabia. Approximately 60% of patients were not aware of the importance of daily foot care. Thus, foot care pamphlets were distributed to patients.

Correlation Between SNPs at the 3'UTR of the FGF2 Gene and Their Interaction with Environmental Factors in Han Chinese Diabetic Peripheral Neuropathy Patients

FGF2 is a neurotrophic factor that can act as a key regulatory molecule of neuroprotection, neurogenesis, and angiogenesis in various injuries. To explore the genetic background of the FGF2 gene on DPN development, this study analyzed the correlation between SNPs in the 3'UTR of the FGF2 gene and their interaction with environmental factors in DPN patients of Han Chinese nationality. Sanger sequencing was used to analyze the FGF2 genotypes at the rs1048201, rs3804158, rs41348645, rs6854081, rs3747676, rs7683093, rs1476215, and rs1476217 loci in 150 DPN patients, 150 NDPN patients, and 150 healthy control patients. Plasma FGF2 levels were measured in all subjects by using ELISAs. Subjects carrying the T allele at the rs1048201 locus in the FGF2 gene had a significantly lower risk of developing DPN compared with subjects carrying the C allele (OR = 0.43, 95% CI = 0.33-0.56, p < 0.01). Subjects with the G genotype at the rs6854081 locus had an exceptionally higher risk of developing DPN than subjects with the T allele (OR = 1.66, 95% CI = 1.39-1.89, p < 0.01). Individuals harboring the G allele at the rs7683093 locus had a markedly higher risk of DPN than patients with the C allele (OR = 1.63, 95% CI = 1.36-1.87, p < 0.01). Finally, individuals having the A genotype at the rs1476215 locus had a significantly higher risk of DPN than individuals carrying the T allele (OR = 1.82, 95% CI = 1.53-2.02, p < 0.01). There was an interaction between age and alcohol consumption and the SNP rs7683093. SNPs at rs1048201, rs6854081, rs7683093, and rs1476215 in the FGF2 3'UTR were strongly associated with plasma levels of FGF2 (p < 0.05). SNPs at the rs1048201, rs6854081, rs7683093, and rs1476215 loci in the FGF2 gene were significantly associated with the risk of DPN. A possible mechanism is that these SNPs affect the expression level of FGF2 by interrupting the binding of microRNAs to target sites in the 3'UTR.

Myo-inositol: its metabolism and potential implications for poultry nutrition-a review

Myo-inositol (MI) has gained relevance in physiology research during the last decade. As a constituent of animal cells, MI was proven to be crucial in several metabolic and regulatory processes. Myo-inositol is involved in lipid signaling, osmolarity, glucose, and insulin metabolism. In humans and rodents, dietary MI was assessed to be important for health so that MI supplementation appeared to be a valuable alternative for treatment of several diseases as well as for improvements in metabolic performance. In poultry, there is a lack of evidence not only related to specific species-linked metabolic processes but also about the effects of dietary MI on performance and health. This review intends to provide information about the meaning of dietary MI in animal metabolism as well as to discuss potential implications of dietary MI in poultry health and performance with the aim to identify open questions in poultry research.

Cutaneous manifestations of diabetic peripheral neuropathy

There is a rise in number of people diagnosed with Diabetes Mellitus. The incidence is rising in modern Indian society because of Industrial development and drastically changing lifestyles. Diabetic neuropathies are microvascular disorders that are usually associated with the duration of Diabetes. Among the various forms, the most common is Diabetic Peripheral Neuropathy. The disease if neglected leads to chronic ulcer formation leading to amputations frequently. Hence the aim of this study is to document the early cutaneous changes and create an early awareness in the importance of controlling Diabetes. The study consisted of 205 patients with Type 2 DM. Participant's neuropathy status was determined based on Neuropathy Disability Score and Diabetic Neuropathy Symptom Score. Among the Skin changes documented, the common changes seen were: Peripheral hair loss in 185 (90.2%), Xerosis in 168 (82%), Anhydrosis in 162 (79%), Plantar Fissures in 136 (66.3%), Plantar Ulcer in 80 (39%), common nail changes documented were Onychomycosis in 165 (80.5%) and Onychauxis in 53 (25.8%) patients in relation to the occupation and duration of Diabetes mellitus. In conclusion, it is important to control glycemic levels in the all stages of Diabetes and institute foot care measures to prevent the complications of neuropathy.

High resolution ultrasonography of the tibial nerve in diabetic peripheral neuropathy

Aim of the study

High-resolution ultrasonography of the tibial nerve is a fast and non invasive tool for diagnosis of diabetic peripheral neuropathy. Our study was aimed at finding out the correlation of the cross sectional area and maximum thickness of nerve fascicles of the tibial nerve with the presence and severity of diabetic peripheral neuropathy.

Material and methods

75 patients with type 2 diabetes mellitus clinically diagnosed with diabetic peripheral neuropathy were analysed, and the severity of neuropathy was determined using the Toronto Clinical Neuropathy Score. 58 diabetic patients with no clinical suspicion of diabetic peripheral neuropathy and 75 healthy non-diabetic subjects were taken as controls. The cross sectional area and maximum thickness of nerve fascicles of the tibial nerves were calculated 3 cm cranial to the medial malleolus in both lower limbs.

Results

The mean cross sectional area (22.63 +/- 2.66 mm²) and maximum thickness of nerve fascicles (0.70 mm) of the tibial nerves in patients with diabetic peripheral neuropathy compared with both control groups was significantly larger, and statistically significant correlation was found with the Toronto Clinical Neuropathy Score (p < 0.001). The diabetic patients with no signs of peripheral neuropathy had a larger mean cross sectional area (14.40 +/- 1.72 mm²) and maximum thickness of nerve fascicles of the tibial nerve (0.40 mm) than healthy non-diabetic subjects (12.42 +/- 1.01 mm² and 0.30 mm respectively).

Conclusion

The cross sectional area and maximum thickness of nerve fascicles of the tibial nerve is larger in diabetic patients with or without peripheral neuropathy than in healthy control subjects, and ultrasonography can be used as a good screening tool in these patients.

Neuropathy-specific alterations in a Mexican population of diabetic patients

Background

Neuropathy is one of the major complications of type 2 diabetes mellitus. Our first aim was to determine the clinical characteristics of a population of diabetic patients with different types of neuropathy. Our next goal was to characterize the cytokine profile (IL-6 and IL-10), nerve growth factor (NGF) and circulating cell-adhesion molecules in these patients. Finally, we aimed to compare the renal function among the groups of neuropathic patients.

Methods

In a cross-sectional study, we included 217 diabetic patients classified in three groups: sensory polyneuropathy with hypoesthesia (DS_hP) or hyperesthesia (DS_HP), and motor neuropathy (DMN). Two control groups were included: one of 26 diabetic non-neuropathic patients (DNN), and the other of 375 non-diabetic (ND) healthy subjects. The participants were attending to the Mexican Institute of Social Security.

Results

The circulating levels of NGF were significantly lower in diabetic patients, compared to healthy subjects. The range of IL-6 and IL-10 levels in neuropathic patients was higher than the control groups; however, several samples yielded null measurements. Neuropathic patients also showed increased circulating levels of the adhesion molecules ICAM, VCAM, and E-Selectin, compared to the ND group. Moreover, neuropathic patients showed reduced glomerular filtration rates compared to healthy subjects (82–103 ml/min per 1.73 m², data as range from 25th–75th percentiles), especially in the group with DMN (45–76 ml/min per 1.73 m²).

Conclusions

Some particular alterations in neuropathic patients included -but were not limited to- changes in circulating NGF, cell adhesion molecules, inflammation, and the worsening of the renal function. This study supports the need for further clinical surveillance and interventions considering a neuropathy-related basis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-017-0939-6) contains supplementary material, which is available to authorized users.

Cerebrolysin improves sciatic nerve dysfunction in a mouse model of diabetic peripheral neuropathy

To examine the effects of Cerebrolysin on the treatment of diabetic peripheral neuropathy, we first established a mouse model of type 2 diabetes mellitus by administering a high-glucose, high-fat diet and a single intraperitoneal injection of streptozotocin. Mice defined as diabetic in this model were then treated with 1.80, 5.39 or 8.98 mL/kg of Cerebrolysin via intraperitoneal injections for 10 consecutive days. Our results demonstrated that the number, diameter and area of myelinated nerve fibers increased in the sciatic nerves of these mice after administration of Cerebrolysin. The results of several behavioral tests showed that Cerebrolysin dose-dependently increased the slope angle in the inclined plane test (indicating an improved ability to maintain body position), prolonged tail-flick latency and foot-licking time (indicating enhanced sensitivity to thermal and chemical pain, respectively, and reduced pain thresholds), and increased an index of sciatic nerve function in diabetic mice compared with those behavioral results in untreated diabetic mice. Taken together, the anatomical and functional results suggest that Cerebrolysin ameliorated peripheral neuropathy in a mouse model of type 2 diabetes mellitus.

High-Glucose-Derived Oxidative Stress-Dependent Heme Oxygenase-1 Expression from Astrocytes Contributes to the Neuronal Apoptosis

An elevated level of glucose has been found in the blood of hyperglycemia and diabetes patients associated with several central nervous system (CNS) complications. These disorders may be due to the up-regulation of many neurotoxic mediators by host cells triggered by high glucose (HG). Moreover, heme oxygenase-1 (HO-1) plays a crucial role in tissue pathological changes such as brain injuries. However, the molecular mechanisms underlying HG-induced HO-1 expression in brain cells remain poorly defined. Thus, we use the rat brain astrocytes (RBA-1) as a model to investigate the signaling mechanisms of HO-1 induction by HG and its effects on neuronal cells. We demonstrated that HG induced HO-1 expression via a reactive oxygen species (ROS)-dependent signaling pathway. NADPH oxidase (Nox)- and mitochondrion-dependent ROS generation led to activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun-N-terminal kinase (JNK) and then activated the downstream transcriptional factors nuclear factor-kappaB (NF-κB) and c-Fos/activator protein 1 (AP-1), respectively. Subsequently, the activated NF-κB and AP-1 turned on transcription of HO-1 gene. These results indicated that in brain astrocytes, activation of MAPK-mediated NF-κB and c-Fos/AP-1 cascades by Nox/ROS and mitoROS-dependent events is essential for HO-1 up-regulation induced by HG. Moreover, we found that HG-induced extracellular ROS increase and HO-1 expression from astrocytes resulted in neuronal apoptosis. These results offers new insights into the mechanisms and effects of the action of HG, supporting that HG may cause brain disorders in the development of diabetes- and hyperglycemia-induced CNS complications such as neurodegenerative diseases.

Relationships between presynaptic inhibition and static postural sway in subjects with and without diabetic neuropathy

[Purpose] Diabetic peripheral neuropathy can often lead to balance impairment. The spinal reflex is a mechanism that is reportedly important for balance, but it has not been investigated in diabetic peripheral neuropathy patients. Moreover, inhibitory or facilitatory behavior of the spinal reflex—known as presynaptic inhibition—is essential for controlling postural sway. The purpose of this study was to compare the differences in as presynaptic inhibition and balance in subjects with and without diabetic peripheral neuropathy to determine the influence of presynaptic inhibition on balance in diabetic peripheral neuropathy patients. [Subjects and Methods] Presynaptic inhibition and postural sway were tested in eight patients (mean age, 58±6 years) and eight normal subjects (mean age, 59±7 years). The mean percent difference in conditioned reflex amplitude relative to the unconditioned reflex amplitude was assessed to calculate as presynaptic inhibition. The single-leg balance index was measured using a computerized balance-measuring device. [Results] The diabetic peripheral neuropathy group showed lower presynaptic inhibition (47±30% vs. 75±22%) and decreased balance (0.65±0.24 vs. 0.38±0.06) as compared with the normal group. No significant correlation was found between as presynaptic inhibition and balance score (R=0.37). [Conclusion] Although the decreased as presynaptic inhibition observed in diabetic peripheral neuropathy patients may suggest central nervous system involvement, further research is necessary to explore the role of presynaptic inhibition in decreased balance in diabetic peripheral neuropathy patients.

TFP5, a peptide derived from p35, a Cdk5 neuronal activator, rescues cortical neurons from glucose toxicity

Multiple lines of evidence link the incidence of diabetes to the development of Alzheimer's disease (AD). Patients with diabetes have a 50 to 75% increased risk of developing AD. Cyclin dependent kinase 5 (Cdk5) is a serine/threonine protein kinase, which forms active complexes with p35 or p39, found principally in neurons and in pancreatic β cells. Recent studies suggest that Cdk5 hyperactivity is a possible link between neuropathology seen in AD and diabetes. Previously, we identified P5, a truncated 24-aa peptide derived from the Cdk5 activator p35, later modified as TFP5, so as to penetrate the blood-brain barrier after intraperitoneal injections in AD model mice. This treatment inhibited abnormal Cdk5 hyperactivity and significantly rescued AD pathology in these mice. The present study explores the potential of TFP5 peptide to rescue high glucose (HG)-mediated toxicity in rat embryonic cortical neurons. HG exposure leads to Cdk5-p25 hyperactivity and oxidative stress marked by increased reactive oxygen species production, and decreased glutathione levels and superoxide dismutase activity. It also induces hyperphosphorylation of tau, neuroinflammation as evident from the increased expression of inflammatory cytokines like TNF-α, IL-1β, and IL-6, and apoptosis. Pretreatment of cortical neurons with TFP5 before HG exposure inhibited Cdk5-p25 hyperactivity and significantly attenuated oxidative stress by decreasing reactive oxygen species levels, while increasing superoxide dismutase activity and glutathione. Tau hyperphosphorylation, inflammation, and apoptosis induced by HG were also considerably reduced by pretreatment with TFP5. These results suggest that TFP5 peptide may be a novel candidate for type 2 diabetes therapy.

Ultrasound findings after surgical decompression of the tarsal tunnel in patients with painful diabetic polyneuropathy: a prospective randomized study

OBJECTIVE

It has been hypothesized that the development of diabetic polyneuropathy (DPN) is due to swelling of the nerve, as well as thickening and stiffening of the surrounding ligaments, causing chronic compression of nerves. We aimed to examine the effect of surgical decompression of the tibial nerve on the mean cross-sectional area (CSA).

RESEARCH DESIGN AND METHODS

We performed a randomized controlled trial of 42 subjects with painful DPN diagnosed using the Diabetic Neuropathy Score. A computer randomized for the surgery arm of the study. A control group consisting of 38 healthy subjects was included. An experienced sonographer measured the CSA and thickness-to-width (T/W) ratio of the tibial nerve, as well as the thickness of the flexor retinaculum.

RESULTS

CSA is significantly larger in patients with painful DPN (8.4 ± 3.9 mm(2)) than in control subjects (6.4 ± 1.3 mm(2)), P = 0.007. The T/W ratio in patients with painful DPN is 0.64 and in control subjects 0.59, P = 0.03. Patients with DPN have a significantly thicker retinaculum (1.07 mm) than control subjects (0.84 mm), P < 0.001. Mean follow-up was 28.2 weeks (range 23-45). Difference between baseline and follow-up in the operated leg was 1.49 mm(2) and in the control leg 1.81 mm(2), P = 0.674.

CONCLUSIONS

Decompression of the tibial nerve does not result in a significant difference between baseline and follow-up in CSA using ultrasound between the operated and control leg. Ultrasound measurements show a significantly increased CSA, a significantly thicker retinaculum, and a significantly increased T/W ratio in patients with painful DPN compared with healthy control subjects. Clinical trial reg. no. NTR2344, www.trialregister.nl.

Peroneal neuropathy misdiagnosed as L5 radiculopathy: a case report

Objective

The purpose of this case report is to describe a patient who presented with a case of peroneal neuropathy that was originally diagnosed and treated as a L5 radiculopathy.

Clinical features

A 53-year old female registered nurse presented to a private chiropractic practice with complaints of left lateral leg pain. Three months earlier she underwent elective left L5 decompression surgery without relief of symptoms.

Intervention and outcome

Lumbar spine MRI seven months prior to lumbar decompression surgery revealed left neural foraminal stenosis at L5-S1. The patient symptoms resolved after she stopped crossing her legs.

Conclusion

This report discusses a case of undiagnosed peroneal neuropathy that underwent lumbar decompression surgery for a L5 radiculopathy. This case study demonstrates the importance of a thorough clinical examination and decision making that ensures proper patient diagnosis and management.

Clinical features and electrodiagnosis of diabetic peripheral neuropathy in the dysvascular patient

Diabetic peripheral neuropathy (DPN) is a common disorder that can lead to limb loss and death. Up to 50% of DPN patients can be asymptomatic. This fact contributes to making DPN the leading cause of lower limb amputation. The degree of heterogeneity in the clinical manifestations of DPN makes diagnosing this condition difficult. This article reviews the characteristics, diagnosis, electrodiagnosis, classification, pathogenesis, and treatment of DPN.

Diabetic neuropathy: therapies on the horizon

OBJECTIVES

This is a review of emerging interventions from the recent preclinical and clinical literature that demonstrate the potential for effectiveness in the therapy of diabetic neuropathy (DN). DN is the most common complication of diabetes mellitus and up to 50% of patients with type 1 and type 2 forms have some or other form of neuropathy. The pathology of DN is characterized by progressive nerve fibre loss that gives rise to positive and negative clinical signs and symptoms such as pain, paraesthesiae and loss of sensation.

KEY FINDINGS

There are very few drugs available to directly treat DN. Those that are clinically indicated provide symptomatic relief but do not repair or reverse underlying nerve damage. However, some agents are in clinical development that may support adult neurons and direct reparative processes after injury stages. Several disease modifying drugs such as aldose reductase inhibitors and protein kinase C inhibitors are in phase III development. Agents on the horizon include neurotrophic factors, growth factors, gene therapy, immunotherapy, poly(ADP-ribose) polymerase inhibitors and non-immunosuppressive immunophilin ligands.

SUMMARY

Progress has been made toward understanding the biochemical mechanisms leading to diabetic neuropathy, and as a result, new treatment modalities are being explored. The pathogenesis, types and approaches for treating DN together with the newer therapeutic interventions on the horizon are discussed.

Additional causes for distal sensory polyneuropathy in diabetic patients

OBJECTIVE

To assess the frequency of additional causes of distal sensory polyneuropathy (DSP) in patients with diabetes mellitus (DM).

METHODS

Retrospective review of patients with DM and DSP during a 5 year period. A quantitative sensory score (QSS) was determined at the initial evaluation and extensive laboratory and EMG studies were performed. Patients with one or more potential causes for DSP were compared to those with DM alone.

RESULTS

Fifty five patients (53%) had potential additional causes for DSP. These included: neurotoxic medications (seven), alcohol abuse (six), and B12 deficiency and renal disease (four each). The most common laboratory abnormalities were: abnormally low levels of vitamin B6 (11) or B1 (10), monoclonal gammopathy (eight), and hypertriglyceridaemia (eight). Twenty six (25%) subjects had more than one additional cause. Nine (9%) had three or more demyelinating features on EMG. There was a trend toward a lower QSS score (p = 0.05) and reduced mean amplitude of the sensory potentials in those with additional causes. Those with additional causes more often had upper limb sensory symptoms (p = 0.001) and sensory findings (p = 0.003).

CONCLUSION

There was a high frequency of additional sources of DSP in patients with DM. These patients more often had sensory symptoms and findings in the hands. Tests that may be useful in the evaluation of DSP in diabetic patients include measures of vitamins B1, B6, B12, serum triglycerides, and immunofixation.