Validation of the Toronto Clinical Scoring System for diabetic polyneuropathy

Diabetic polyneuropathies: update on research definition, diagnostic criteria and estimation of severity

Prior to a joint meeting of the Neurodiab Association and International Symposium on Diabetic Neuropathy held in Toronto, Ontario, Canada, 13-18 October 2009, Solomon Tesfaye, Sheffield, UK, convened a panel of neuromuscular experts to provide an update on polyneuropathies associated with diabetes (Toronto Consensus Panels on DPNs, 2009). Herein, we provide definitions of typical and atypical diabetic polyneuropathies (DPNs), diagnostic criteria, and approaches to diagnose sensorimotor polyneuropathy as well as to estimate severity. Diabetic sensorimotor polyneuropathy (DSPN), or typical DPN, usually develops on long-standing hyperglycaemia, consequent metabolic derangements and microvessel alterations. It is frequently associated with microvessel retinal and kidney disease-but other causes must be excluded. By contrast, atypical DPNs are intercurrent painful and autonomic small-fibre polyneuropathies. Recognizing that there is a need to detect and estimate severity of DSPN validly and reproducibly, we define subclinical DSPN using nerve conduction criteria and define possible, probable, and confirmed clinical levels of DSPN. For conduct of epidemiologic surveys and randomized controlled trials, it is necessary to pre-specify which attributes of nerve conduction are to be used, the criterion for diagnosis, reference values, correction for applicable variables, and the specific criterion for DSPN. Herein, we provide the performance characteristics of several criteria for the diagnosis of sensorimotor polyneuropathy in healthy subject- and diabetic subject cohorts. Also outlined here are staged and continuous approaches to estimate severity of DSPN.

Reproducibility of in vivo corneal confocal microscopy as a novel screening test for early diabetic sensorimotor polyneuropathy

AIM

With the goal of identifying a valid biomarker of early diabetic sensorimotor polyneuropathy, we aimed to identify the most reliable in vivo corneal confocal microscopy (CCM) parameter for detection of abnormality of small nerve fibre morphology.

METHODS

Cross-sectional examination of 46 subjects (26 with Type 1 diabetes and 20 healthy volunteers) examined by corneal confocal microscopy for intra- and interobserver reproducibility by the intraclass correlation coefficient method. Corneal nerve fibre density, nerve branch density, nerve fibre length and tortuosity were measured on the same day that subjects underwent clinical and electrophysiological examination.

RESULTS

The 26 subjects with Type 1 diabetes had mean age and diabetes duration 42.8 ± 16.9 and 22.7 ± 16.4 years, respectively. Twelve of those subjects (46%) did not meet criteria for diabetic sensorimotor polyneuropathy, while five (19%) had mild, three (12%) had moderate and six (23%) had severe diabetic sensorimotor polyneuropathy. None of the healthy volunteers (mean age 41.4 ± 17.3 years) had polyneuropathy. Re-examination of selected corneal confocal microscopy images or sets of 40 images yielded very good to excellent intraclass correlation coefficients for all parameters. However, only one parameter (corneal nerve fibre length) emerged with consistently very good reproducibility using a clinically relevant 'study-level' protocol of subject re-examination (intra-observer intraclass correlation coefficient 0.72; interobserver intraclass correlation coefficient 0.73). Despite no differences in intraclass correlation coefficient between subgroups, corneal nerve fibre length was significantly lower (14.76 vs. 16.15 mm/mm(2), P = 0.04) in those with diabetes.

CONCLUSIONS

Development of corneal confocal microscopy may need to focus on the measurement of corneal nerve fibre length, as it appears to have superior reliability in comparison with other parameters, and as evidence exists for its potential as a clinical biomarker of early diabetic sensorimotor polyneuropathy.

Dorsal versus ventral monofilament testing of the great toe for the identification of diabetic sensorimotor polyneuropathy

We tested whether monofilament examination of the ventral rather than dorsal aspect of the great toe could better detect diabetic sensorimotor polyneuropathy (DSP). Although dorsal testing had better overall performance for identifying Subclinical DSP, the magnitude of benefit was small and there was no difference in identifying Clinical DSP.

Serum γ-glutamyltransferase and associated damage among a She Chinese population

OBJECTIVE

It has been suggested that serum γ-glutamyltransferase is independently associated with cardiovascular mortality and atherosclerosis. The present study is to investigate the relationship between serum γ-glutamyltransferase and potential associated damage in an adult She Chinese population.

METHOD

A multistage, stratified, cluster, random sampling method was used to select an ethnically representative group of individuals aged 20-80 years in the general population. Brachial-ankle pulse-wave velocity was used to assess arterial stiffness in the general population and the Toronto Clinical Neuropathy Scoring System was used to detect diabetic peripheral polyneuropathy among populations with diabetes.

RESULTS

A total of 5385 subjects were entered into the analysis. Serum γ-glutamyltransferase levels were classified into four groups using the 25th, 50th and 75th percentiles as cut points (males: < 20, 20-29, 29-52 and > 52 U/l; females: < 13, 13-18, 18-25 and > 25 U/l). As compared with the first quartile, the relative risks of arterial stiffness were 1.418, 1.667 and 2.394 in the other three categories, respectively (test for trend P < 0.05). After adjustment in five models, serum γ-glutamyltransferase was still a risk factor of arterial stiffness. We found inverted U-shape curves in both genders and the third quartile (male: 29 52 U/l; female: 18-25 U/l) had the highest odds ratios of 1.640 and 1.529, respectively.

CONCLUSIONS

We demonstrated that high serum γ-glutamyltransferase concentrations were directly associated with the increased risk of arterial stiffness, in general, and with peripheral polyneuropathy in subjects with diabetes in an ethnic She Chinese population. Alcohol use, gender, BMI and blood pressure were related to serum γ-glutamyltransferase and were involved in the relationship between serum γ-glutamyltransferase and brachial-ankle pulse-wave velocity.

A novel robotic monofilament test for diabetic neuropathy

OBJECTIVE

The use of the Semmes-Weinstein (SW) monofilament test is recommended as a screening method for diabetic neuropathy. It offers an important chance to prevent further complications of diabetic foot. We aimed to develop a prototype Robotic Monofilament Inspector that can be used as a standard machine for screening of diabetic neuropathy.

METHODS

Development was divided into three parts: computer software, control box, and Robotic Monofilament Inspector. The examiner conducted the SW test (by hand and by robotic inspector), vibration perception threshold, and Toronto Clinical Scoring System without knowledge of patient information. The unpaired t test or Wilcoxon rank-sum test was used to determine the differences between independent groups in terms of continuous outcomes, while the χ(2) test was used to determine categorical outcomes. Agreement between the various diabetic neuropathy tests was measured using the kappa statistic.

RESULTS

The SW test and vibration perception threshold were more valid tests for neuropathy than the Toronto test. The robotic test was in excellent agreement with the two former tests and appeared to be valid (kappa statistic, 0.35-0.81). Another indirect evidence for the validity of the robotic test was the finding that diabetic patients with foot ulcers had a higher prevalence of neuropathy (77%vs. 38%). This might indicate that the robotic test was more valid than the manual test.

CONCLUSION

The Robotic Monofilament Inspector could be used as a simple screening machine. This prototype may be developed further for routine clinical use.

Chinese herbal medicine for diabetic peripheral neuropathy

BACKGROUND

Chinese herbal medicine is frequently used for treating diabetic peripheral neuropathy in China. Many controlled trials have been undertaken to investigate its efficacy.

OBJECTIVES

To assess the beneficial effects and harms of Chinese herbal medicine for people with diabetic peripheral neuropathy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Specialized Register (15 June 2010), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 2, 2010 in The Cochrane Library), MEDLINE (January 1966 to June 2010), EMBASE (January 1980 to June 2010), AMED (January 1985 to June 2010), Chinese Biomedical Database (CBM) (1979 to June 2010), Chinese National Knowledge Infrastructure Database (CNKI) (1979 to June 2010), and VIP Chinese Science and Technique Journals Database (1989 to June 2010). We searched for unpublished literature in the Chinese Conference Papers Database and Chinese Dissertation Database (from inception to March 2010). No language or publication restrictions were used.

SELECTION CRITERIA

We included randomized controlled trials of Chinese herbal medicine (with a minimum of four weeks treatment duration) for people with diabetic peripheral neuropathy compared with placebo, no intervention, or conventional interventions. Trials of herbal medicine plus a conventional drug versus the drug alone were also included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and evaluated trial quality. We contacted study authors for additional information. The data analyses were carried out using Review Manager 5.1 (Cochrane software).

MAIN RESULTS

Thirty-nine randomized trials involving 2890 participants were included. All trials were conducted and published in China. Thirty different herbal medicines were tested in these trials, including four single herbs (extracts from a single herb), eight traditional Chinese patent medicines, and 18 self-concocted Chinese herbal compound prescriptions. The trials reported on global symptom improvement (including improvement in numbness or pain) and changes in nerve conduction velocity. There was inadequate reporting on adverse events in the included trials. Most of the trials did not mention whether they monitored adverse effects at all. Only two trials reported adverse events: one occurred in the control group in one trial and in which group was unclear in the other trial . Conclusions cannot be drawn from this review about the safety of herbal medicines due to inadequate reporting. Most of the trials were of low methodological quality and therefore the interpretation of any positive findings for the efficacy of the included Chinese herbal medicines for treating diabetic peripheral neuropathy should be made with caution.

AUTHORS' CONCLUSIONS

Based on this systematic review, there is no evidence to support the objective effectiveness and safety of Chinese herbal medicines for diabetic peripheral neuropathy. No well designed, randomized placebo controlled trial with objective outcome measures has been conducted.

Responsiveness of the foot and ankle ability measure (FAAM) in individuals with diabetes

BACKGROUND

The impact of diabetes on physical function pose a challenge in assessing clinical outcomes.

OBJECTIVE

The purpose of this study was to provide evidence of responsiveness for the foot and ankle ability measures (FAAM) in individuals with diabetes mellitus.

METHODS

The two most recent FAAM scores of 155 diabetic patients treated for foot/ankle pathology were analyzed. Based on physical component summary (PCS) scores of the SF-36, subjects were categorized as improved (>7-point positive change), worsened (>7-point negative change), or unchanged (<7-point change). Analyses of the worsened and improved groups were compared to the unchanged group using two-way repeated measures ANOVAs and ROC curve analyses.

RESULTS

The ANOVAs demonstrated a significant difference between groups (P = 0.001). ROC curves analysis for detecting an improvement or decline in status were 0.73 (95% CI 0.62-0.84) and 0.70 (95% CI 0.59-0.81), respectively. An increase in FAAM score of 9 points represented the minimal clinically important difference (MCID) with 0.64 sensitivity and 0.78 specificity. A decrease in FAAM score of 2 points represented a MCID with 0.65 sensitivity and 0.61 specificity.

CONCLUSIONS

The FAAM demonstrated responsiveness to change in individuals with orthopedic foot and ankle dysfunction complicated by diabetes and can be used to measure patient outcomes over a 6-month period.

Evaluation of the diabetic foot according to Wagner’s classification in a rural teaching hospital

Diabetic foot is a common, preventable complication of diabetes mellitus. This was a prospective study (April 2004 to October 2005) of 55 diabetic foot patients attending surgical out and in-patient departments at a rural hospital in Mahrastra, India. To determine the prevalence of diabetic foot amongst our patients with diabetes and the associated risk factors. All patients underwent medical assessment, including foot examination, those with diabetic foot answered an interviewer-administered questionnaire on foot healthcare practices. Symptoms, examination findings, glycaemic control, duration and classification of diabetes, occupation and smoking habits were cross studied with diabetic foot according to Wagner’s grading. The prevalence of diabetic foot was 11% and 84% of patients were men. The commonest presentation was Wagner’s grade 2 diabetic foot (34.5%) and most patients (69%) worked outside. The majority of patients with Wagner’s grade 2—5 had uncontrolled diabetes. Neuropathic and vasculopathic components were major predictors of diabetic foot. More than half (64.5%) of our patients were ignorant of foot healthcare practices. Patients with diabetes at this rural clinic need to be better informed on how to examine and care for their feet. They would also benefit from measures to help them improve glycaemic control.

Asymptomatic small fiber neuropathy in diabetes mellitus: investigations with intraepidermal nerve fiber density, quantitative sensory testing and laser-evoked potentials

This study aimed at evaluating the performance of a battery of morphological and functional tests for the assessment of small nerve fiber loss in asymptomatic diabetic neuropathy (DNP). Patients diagnosed for ≥10 years with type 1 (n = 10) or type 2 (n = 13) diabetes mellitus (DM) without conventional symptoms or signs of DNP were recruited and compared with healthy controls (n = 18) and patients with overt DNP (n = 5). Intraepidermal nerve fiber density (IENFd) was measured with PGP9.5 immunostaining on punch skin biopsies performed at the distal leg. Functional tests consisted of quantitative sensory testing (QST) for light-touch, cool, warm and heat pain detection thresholds and brain-evoked potentials with electrical (SEPs) and CO(2) laser stimulation [laser-evoked potentials (LEPs)] of hand dorsum and distal leg using small (0.8 mm(2)) and large (20 mm(2)) beam sizes. Results confirmed a state of asymptomatic DNP in DM, but only at the distal leg. Defining a critical small fiber loss as a reduction of IENFd ≤-2 z scores of healthy controls, this state prevailed in type 2 (30%) over type 1 DM (10%) patients despite similar disease duration and current glycemic control. LEPs with the small laser beam performed best in terms of sensitivity (91%), specificity (83%) and area-under-the ROC curve (0.924). Although this performance was not statically different from that of warm and cold detection threshold, LEPs offer an advantage over QST given that they bypass the subjective report and are therefore unbiased by perceptual factors.

How sensitive is the case definition for diabetic sensorimotor polyneuropathy to the use of different symptoms, signs, and nerve conduction parameters in type 1 diabetes?

We examined the impact of variation in the interpretation of published guidelines for polyneuropathy diagnosis in type 1 diabetes. Though insensitive to clinical criteria, results indicated that case definition was substantially influenced by variation in electrophysiological criteria emphasizing the need for research into targeted algorithms for incorporation into future guidelines.

Short-term metabolic change is associated with improvement in measures of diabetic neuropathy: a 1-year placebo cohort analysis

AIMS

Randomized clinical trials have frequently shown improvement in diabetic sensorimotor polyneuropathy in placebo-treated participants, counter to the prevailing concept that it deteriorates with time. We aimed to determine the variables associated with this paradoxical nerve function improvement.

METHODS

Participants with diabetic sensorimotor polyneuropathy randomized to placebo in a multi-centre, double-blind study were evaluated for the primary outcome of 1-year change in the summed sensory nerve conduction velocity of the bilateral sural and non-dominant median nerves. Association with clinical and biochemical variables measured at 13 time points were examined.

RESULTS

The 134 participants had mild to moderate diabetic sensorimotor polyneuropathy of 4.6 years' duration and mean 1-year improvement of 2.0 ± 8.0 m/s. Primary outcome measures were available for 122 participants (91%). In multivariate analyses, the change in HbA(1c) and serum triglycerides from baseline to 2 months demonstrated the strongest association, even independent of baseline and end-of-study levels. According to quintiles of change, we determined thresholds: participants with salutary improvement in HbA(1c) (exceeding a drop of -0.8%) or whose triglycerides did not increase (by 0.32 mmol/l or more) experienced significant improvement (2.9 m/s), while those with salutary levels of both these variables had an exaggerated improvement (5.1 m/s). In comparison, those with non-salutary changes in both variables experienced a loss of -4.9 m/s (ANOVA P=0.0014).

CONCLUSIONS

In mild to moderate diabetic sensorimotor polyneuropathy, short-term improvements in glycaemic control and serum triglyceride levels have an independent, additive and durable effect on restoration of nerve function.

Levodopa, methylmalonic acid, and neuropathy in idiopathic Parkinson disease

OBJECTIVE

Peripheral neuropathy (PN) is thought to be coincidental in patients with idiopathic Parkinson disease (IPD). We sought to examine the prevalence of PN in a population of IPD patients and a potential relationship to levodopa use and fasting methylmalonic acid (MMA) levels.

METHODS

In a prospective cohort study, IPD patients randomly selected from a comprehensive database were compared to control subjects regarding the presence and severity of PN using clinical and electrophysiological measures. IPD severity was determined using the Unified Parkinson's Disease Rating Scale (UPDRS). We determined the relation of levodopa use with serum levels of cobalamin, MMA, and homocysteine (Hcy). We also explored the association between presence and severity of PN and age, duration of IPD, cumulative levodopa dosing, cobalamin, MMA, and Hcy levels.

RESULTS

Fifty-eight randomly selected IPD patients were compared to 58 age- and sex-matched controls. PN was present in 55% of IPD patients and 9% of controls. Patients with IPD had greater prevalence of PN and fasting MMA/Hcy levels than controls. IPD patients with PN were older and exhibited higher UPDRS scores, fasting MMA/Hcy levels, and cumulative levodopa exposure. PN severity in IPD subjects positively correlated with both levodopa exposure and MMA levels.

INTERPRETATION

IPD patients have a higher prevalence of PN than controls. Although causality is not established, levodopa exposure is associated with MMA elevation and sensorimotor neuropathy in IPD patients. Cobalamin replacement concurrent with levodopa therapy should be considered to protect against development of PN in IPD patients.

Prediction of incident diabetic neuropathy using the monofilament examination: a 4-year prospective study

OBJECTIVE

To determine the specific monofilament examination score that predicts the subsequent 4-year incidence of diabetic neuropathy with the highest degree of diagnostic accuracy.

RESEARCH DESIGN AND METHODS

Longitudinal follow-up of 175 of 197 (89%) participants in the Toronto Diabetic Neuropathy Cohort without baseline neuropathy for incident neuropathy. We examined the baseline monofilament examination score (and other simple sensory screening tests) by receiver operating characteristic (ROC) curve analysis.

RESULTS

Incident diabetic neuropathy developed in 50 (29%) participants over a mean follow-up of 4.1 years (interquartile range 2.6-7.1 years). Although male sex, longer diabetes duration, taller height, and higher blood pressure at baseline were associated with incident neuropathy, the strongest association was with a lower baseline monofilament score (score out of 8 was 3.7 +/- 2.5 for incident neuropathy vs. 5.7 +/- 2.3 for those who did not develop neuropathy; P < 0.001). The optimal threshold score for risk of incident neuropathy was <or=5 sensate stimuli out of 8, with 72% sensitivity, 64% specificity, positive and negative likelihood ratios of 2.5 and 0.35, and positive and negative predictive values of 87 and 46%, respectively (chi(2) = 20.7, P < 0.001). Area under the ROC curve was significantly greater for the monofilament examination compared with that for other simple sensory tests.

CONCLUSIONS

A simple threshold of <or=5 sensate stimuli out of 8 discriminates 4-year risk of diabetic neuropathy with acceptable operating characteristics. Although there are limitations in its specificity for prediction of future neuropathy onset, the monofilament examination is appropriate as a simple diabetic neuropathy screening instrument generalizable to the clinical setting.

An open-label, non-randomized comparison of venlafaxine and gabapentin as monotherapy or adjuvant therapy in the management of neuropathic pain in patients with peripheral neuropathy

Although many therapies are used in the management of neuropathic pain (NeP) due to polyneuropathy (PN), few comparison studies exist. We performed a prospective, non-randomized, unblended, efficacy comparison of the serotonin-norepinephrine reuptake inhibitor venlafaxine, as either monotherapy or adjuvant therapy, with a first-line medication for NeP, gabapentin, in patients with PN-related NeP. VAS pain scores were assessed after 3 and 6 months in intervention groups and in a cohort of patients receiving no pharmacotherapy. In a total of 223 patients, we analyzed pain quantity and quality (visual analogue scale [VAS] score, Brief Pain Inventory [BPI]), quality of life and health status measures [EuroQol 5 Domains, EQ-5D], Medical Outcomes Sleep Study Scale [MOSSS], Hospital Anxiety and Depression Scale [HADS] and Short Form 36 Health Survey [SF-36]) after 6 months of therapy. Significant improvements in VAS pain scores occurred for all treatment groups after 6 months. Improvements in aspects of daily life and anxiety were identified in all treatment groups. Our data suggest that monotherapy or adjuvant therapy with venlafaxine is comparable to gabapentin for NeP management. We advocate for head-to-head, randomized, double-blinded studies of current NeP therapies.

Association of metformin, elevated homocysteine, and methylmalonic acid levels and clinically worsened diabetic peripheral neuropathy

OBJECTIVE

The severity of peripheral neuropathy in diabetic patients varies for unclear reasons. Long-term use of metformin is associated with malabsorption of vitamin B(12) (cobalamin [Cbl]) and elevated homocysteine (Hcy) and methylmalonic acid (MMA) levels, which may have deleterious effects on peripheral nerves. The intent of this study was to clarify the relationship among metformin exposure, levels of Cbl, Hcy, and MMA, and severity of peripheral neuropathy in diabetic patients. We hypothesized that metformin exposure would be associated with lower Cbl levels, elevated Hcy and MMA levels, and more severe peripheral neuropathy.

RESEARCH DESIGN AND METHODS

This was a prospective case-control study of patients with type 2 diabetes and concurrent symptomatic peripheral neuropathy, comparing those who had received >6 months of metformin therapy (n = 59) with those without metformin exposure (n = 63). Comparisons were made using clinical (Toronto Clinical Scoring System and Neuropathy Impairment Score), laboratory (serum Cbl, fasting Hcy, and fasting MMA), and electrophysiological measures (nerve conduction studies).

RESULTS

Metformin-treated patients had depressed Cbl levels and elevated fasting MMA and Hcy levels. Clinical and electrophysiological measures identified more severe peripheral neuropathy in these patients; the cumulative metformin dose correlated strongly with these clinical and paraclinical group differences.

CONCLUSIONS

Metformin exposure may be an iatrogenic cause for exacerbation of peripheral neuropathy in patients with type 2 diabetes. Interval screening for Cbl deficiency and systemic Cbl therapy should be considered upon initiation of, as well as during, metformin therapy to detect potential secondary causes of worsening peripheral neuropathy.

A 4 year follow-up study of cognitive functioning in patients with type 2 diabetes mellitus

AIMS/HYPOTHESIS

Type 2 diabetes mellitus is associated with moderate decrements in cognitive functioning, mainly in verbal memory, information-processing speed and executive functions. How this cognitive profile evolves over time is uncertain. The present study aims to provide detailed information on the evolution of cognitive decrements in type 2 diabetes over time.

METHODS

Sixty-eight patients with type 2 diabetes and 38 controls matched for age, sex and estimated IQ performed an elaborate neuropsychological examination in 2002-2004 and again in 2006-2008, including 11 tasks covering five cognitive domains. Vascular and metabolic determinants were recorded. Data were analysed with repeated measures analysis of variance, including main effects for group, time and the group x time interaction.

RESULTS

Patients with type 2 diabetes showed moderate decrements in information-processing speed (mean difference in z scores [95% CI] -0.37 [-0.69, -0.05]) and attention and executive functions (-0.25 [-0.49, -0.01]) compared with controls at both the baseline and the 4 year follow-up examination. After 4 years both groups showed a decline in abstract reasoning (-0.16 [-0.30, -0.02]) and attention and executive functioning (-0.29 [-0.40, -0.17]), but there was no evidence for accelerated cognitive decline in the patients with type 2 diabetes as compared with controls (all p > 0.05).

CONCLUSIONS/INTERPRETATION

In non-demented patients with type 2 diabetes, cognitive decrements are moderate in size and cognitive decline over 4 years is largely within the range of what can be viewed in normal ageing. Apparently, diabetes-related cognitive changes develop slowly over a prolonged period of time.

Abnormal cold perception in the lower limbs: a sensitive indicator for detection of polyneuropathy in patients with type 1 diabetes mellitus

Diabetic peripheral neuropathy differs in type 1 and type 2 diabetes. The aim of this study was to evaluate how signs and symptoms of neuropathy correlated with defects in motor and sensory nerve conduction velocity (MCV and SCV) and sensory perception thresholds in patients with type 1 diabetes. MCV and SCV in peroneal and sural nerves and vibratory, warm and cold perception thresholds (VPT, WPT, CPT) were evaluated in the lower limbs of 127 patients (42+/-7.9 years old, duration of diabetes, 16+/-11 years and HbA1c, 7.7+/-1.4%). The results were compared with clinical findings (neuropathy impairment assessment, NIA) and sensory symptoms (neurological symptom assessment, NSA). Sensory symptoms were present in 24% of patients, 91% had at least one abnormal finding in the neurological examination and 84% had abnormal nerve conduction. The greatest deviation from normal was observed for CPT on the dorsum of the foot and peroneal MCV. NIA and NSA correlated with all electrophysiological measurements in the foot and big toe. It is concluded that clinical findings correlate well with electrophysiological abnormalities in patients with type 1 diabetic neuropathy. An elevated CPT for the foot was the most pronounced sensory defect.

Ranirestat for the management of diabetic sensorimotor polyneuropathy

OBJECTIVE

Aldose reductase inhibitors (ARIs) are potential disease modifiers for diabetes complications. We aimed to determine whether ranirestat, an ARI, could slow or reverse the course of diabetic sensorimotor polyneuropathy (DSP).

RESEARCH DESIGN AND METHODS

A total of 549 patients with DSP were randomly assigned to treatment with placebo or 10, 20, or 40 mg/day ranirestat for 52 weeks in this multicenter, double-blind study. Efficacy was evaluated by nerve conduction studies, the modified Toronto Clinical Neuropathy Score (mTCNS), and quantitative sensory tests (QSTs).

RESULTS

At week 52, the summed sensory (bilateral sural plus proximal median sensory) nerve conduction velocity (NCV) did not show significant changes from baseline (2.0 m/s for placebo compared with 3.2-3.8 m/s for ranirestat). Significant improvement in the summed motor (peroneal, tibial, and median) NCV was observed with 20 and 40 mg/day ranirestat treatment at week 12 (P <or= 0.05) and at weeks 24 and 36 and in peroneal motor NCV at weeks 36 and 52 (P <or= 0.05) for the 20 mg/day ranirestat group. The mTCNS and QST results did not differ among the groups during the study. Ranirestat was well tolerated with no pertinent differences in drug-related adverse events or in effects on clinical laboratory parameters, vital signs, or electrocardiograms among the four groups.

CONCLUSIONS

Treatment with ranirestat appears to have an effect on motor nerve function in mild to moderate DSP, but the results of this study failed to show a statistically significant difference in sensory nerve function relative to placebo.

Quantification of sweat gland innervation: a clinical-pathologic correlation

OBJECTIVE

To evaluate a novel method to quantify the density of nerve fibers innervating sweat glands in healthy control and diabetic subjects, to compare the results to an unbiased stereologic technique, and to identify the relationship to standardized physical examination and patient-reported symptom scores.

METHODS

Thirty diabetic and 64 healthy subjects had skin biopsies performed at the distal leg and distal and proximal thigh. Nerve fibers innervating sweat glands, stained with PGP 9.5, were imaged by light microscopy. Sweat gland nerve fiber density (SGNFD) was quantified by manual morphometry. As a gold standard, three additional subjects had biopsies analyzed by confocal microscopy using unbiased stereologic quantification. Severity of neuropathy was measured by standardized instruments including the Neuropathy Impairment Score in the Lower Limb (NIS-LL) while symptoms were measured by the Michigan Neuropathy Screening Instrument.

RESULTS

Manual morphometry increased with unbiased stereology (r = 0.93, p < 0.01). Diabetic subjects had reduced SGNFD compared to controls at the distal leg (p < 0.001), distal thigh (p < 0.01), and proximal thigh (p < 0.05). The SGNFD at the distal leg of diabetic subjects decreased as the NIS-LL worsened (r = -0.89, p < 0.001) and was concordant with symptoms of reduced sweat production (p < 0.01).

CONCLUSIONS

We describe a novel method to quantify the density of nerve fibers innervating sweat glands. The technique differentiates groups of patients with mild diabetic neuropathy from healthy control subjects and correlates with both physical examination scores and symptoms relevant to sudomotor dysfunction. This method provides a reliable structural measure of sweat gland innervation that complements the investigation of small fiber neuropathies.

Neuropathy as a potential complication of levodopa use in Parkinson's disease

The presence and potential etiologies of peripheral neuropathy (PN) in patients with Parkinson's Disease (PD) is unknown. We examined for presence of PN in patients with PD. From a PD patient population of 500 patients screened for features of symptomatic PN, patients were further selected for clinical, electrophysiological, and laboratory studies related to PN. This PD patient population with idiopathic PN (PD-IPN) was compared to a group of PD patients without PN (PD-only), and a large group of patients without PD with idiopathic PN (IPN) for abnormalities in Cbl, fasting homocysteine (Hcy), and fasting methylmalonic acid (MMA) levels. PD-IPN and IPN patients identified with abnormalities in Cbl, Hcy, or MMA levels were treated with intramuscular Cbl for 1 to 2 years. Of 49 PD patients with symptomatic PN, 34 patients (69%) had PD-IPN, and 32/34 (94%) had abnormal Hcy or MMA levels as compared to 26/258 (10%) of IPN patients. Cumulative lifetime L-dopa dosage and fasting MMA levels were associated with PN severity. Cbl therapy led to improvements in Hcy and MMA levels in all groups, and PN in PD-IPN patients stabilized during therapy. PN in PD patients may be associated with iatrogenic Cbl metabolic abnormalities. Alternatively PN may be a peripheral nervous system manifestation of PD.

Validity of the Foot and Ankle Ability Measure (FAAM) in Diabetes Mellitus

BACKGROUND

The Foot and Ankle Ability Measure (FAAM) has been shown to be reliable, valid, and responsive in a general orthopaedic population. The purpose of this study was to evaluate validity for the FAAM in individuals with diabetes. It was hypothesized that FAAM scores would relate to measures of physical function while not correspond to measures of mental health. It was also hypothesized that FAAM scores would be different based on reported general health.

MATERIALS AND METHODS

Eighty-three subjects with diabetes and foot and ankle related complaints completed intake information during a routine clinical visit. Subjects had an average age of 60.3 (range, 21 to 93; SD 13.7) years. Subjects were grouped based on their reported general health with 55 (64.7%) and 28 (32.9%), reporting excellent-good and fair-poor general health, respectively. Pearson correlation coefficients were used to assess the relationship between the FAAM and SF-36. As evidence for discriminative validity, one-way ANOVA was used to determine if FAAM scores could distinguish between individuals that reported excellent-good from those that reported fair-poor levels of general health.

RESULTS

The FAAM had high correlation to the SF-36 physical function subscale (r > 0.60) and physical component summary score (r > 0.70) and significantly (p < 0.005) lower correlation to the mental health subscale (r < 0.33) and mental component summary score (r < 0.30). One-way ANOVA found those that reported excellent-good general health scored significantly higher on the ADL subscale (57 vs 44 [F(1,82) = 4.6, p = 0.035]) but did score differently on the Sports subscales (32 vs 22 [F(1,70)=1.7, p = 0.20]).

CONCLUSION

This study offers evidence of validity for the FAAM ADL subscale as an outcome instrument to measure physical function in individuals with diabetes and foot and/or ankle related disorders. Further research is needed for the Sports subscale in individuals with diabetes who are functioning at a higher level.

Reliability and validity of the modified Toronto Clinical Neuropathy Score in diabetic sensorimotor polyneuropathy

INTRODUCTION

A reliable and valid clinical tool to capture symptoms and signs of diabetic sensorimotor polyneuropathy (DSP) for use in clinical research trials is urgently needed. The validated Toronto Clinical Neuropathy Score (TCNS) was modified to improve sensitivity to early DSP changes. We aimed to assess the reproducibility of this modified tool, the mTCNS and to determine its validity relative to the precursor TCNS.

METHODS

Sixty-five patients (six Type 1, 59 Type 2 diabetes) with diabetes duration 13 +/- 8 years were accrued from four study sites and examined on 2 days for internal consistency and inter- and intra-rater reliability of the mTCNS. In the absence of a single quantitative gold-standard measure for DSP, results of the mTCNS were compared with the precursor TCNS for the purpose of estimating validity.

RESULTS

Internal consistency of the two domains within the mTCNS was good (Cronbach's alpha 0.78). Very good inter-rater reliability for the mTCNS was demonstrated by an intra-class correlation coefficient for the mTCNS of 0.87 (95% confidence interval, 0.79-0.91), which was similar in magnitude to that of the TCNS (0.83; 95% confidence interval, 0.75-0.89). Intra-rater reliability testing of the mTCNS showed moderate to good correlation for individual symptoms and sensory tests (Cohen's kappa values of 0.54-0.73). The mTCNS shared moderate correlation with the precursor TCNS (Pearson correlation coefficient, 0.58).

DISCUSSION

The mTCNS, a clinical score with higher face validity for tracking mild to moderate DSP, has sufficient reliability and validity relative to its precursor TCNS for use in clinical research.

Ranirestat: A Selective Aldose Reductase Inhibitor for Diabetic Sensorimotor Polyneuropathy

Objective:

To review the pharmacology, pharmacokinetics, clinical efficacy, and safety of ranirestat, an oral aldose reductase inhibitor with a unique chemical structure, as treatment of diabetic sensorimotor polyneuropathy in patients with diabetes mellitus.

Data Sources:

Primary literature and review articles were identified by searching MEDLINE (1950–June 2008), EMBASE (1991–June 2008), International Pharmaceutical Abstracts (1970–June 2008), and Google Scholar using the key terms ranirestat, AS-3201, SX-3030, aldose reductase inhibitors, diabetes mellitus, and peripheral neuropathy. Additional articles were identified from the bibliographies of the obtained literature.

Study Selection and Data Extraction:

Reviewed literature was restricted to available English-language articles. Preclinical and clinical trials were reviewed. One Phase 2 clinical trial and its extension study were identified. No data have yet been reported from Phase 3 trials that were conducted between 2004 and 2006.

Data Synthesis:

Ranirestat is a selective and reversible inhibitor of aldose reductase. Nerve damage is reduced by inhibiting this key enzyme in the polyol pathway, thus preventing the accumulation of sorbitol and fructose. Ranirestat has been compared with placebo in randomized, double-blind, controlled trials. Improvement in nerve function, sensation, and clinical grading scale were noted. Ranirestat was reported to be well tolerated.

Conclusions:

Ranirestat may offer a clinical advantage over current treatment modalities as the first agent to address one factor in the underlying cause of diabetic sensorimotor polyneuropathy. Further studies should be done on safety, efficacy, tolerability, and quality of life to determine how successful this agent will be in the treatment of diabetic sensorimotor polyneuropathy.

ACPE Universal Program Numbers:

407-000-08-056-H01-P (Pharmacists); 407-000-08-056-H01-T (Technicians)

Stratified analyses for selecting appropriate target patients with diabetic peripheral neuropathy for long-term treatment with an aldose reductase inhibitor, epalrestat

AIMS

The long-term efficacy of epalrestat, an aldose reductase inhibitor, in improving subjective symptoms and nerve function was comprehensively assessed to identify patients with diabetic peripheral neuropathy who responded to epalrestat treatment.

METHODS

Stratified analyses were conducted on data from patients in the Aldose Reductase Inhibitor-Diabetes Complications Trial (ADCT). The ADCT included patients with diabetic peripheral neuropathy, median motor nerve conduction velocity > or = 40 m/s and with glycated haemoglobin (HbA(1c)) < or = 9.0%. Longitudinal data on HbA(1c) and subjective symptoms of the patients for 3 years were analysed (epalrestat n = 231, control subjects n = 273). Stratified analyses based on background variables (glycaemic control, grades of retinopathy or proteinuria) were performed to examine the relationship between subjective symptoms and nerve function. Multiple logistic regression analyses were conducted.

RESULTS

Stratified subgroup analyses revealed significantly better efficacy of epalrestat in patients with good glycaemic control and less severe diabetic complications. In the control group, no improvement in nerve function was seen regardless of whether symptomatic benefit was obtained. In the epalrestat group, nerve function deteriorated less or improved in patients whose symptoms improved. The odds ratio of the efficacy of epalrestat vs. control subjects was approximately 2 : 1 (4 : 1 in patients with HbA(1c) < or = 7.0%).

CONCLUSION

Our results suggest that epalrestat, an aldose reductase inhibitor, will provide a clinically significant means of preventing and treating diabetic neuropathy if used in appropriate patients.

Painful diabetic neuropathy

The podiatric physician often encounters complex painful neuropathies in daily practice. Diabetic neuropathy is one form of chronic neuropathic pain dealt with on a regular basis. The goal of this article is to review the pathophysiology, diagnosis, and treatment options of this complaint. Medical and surgical interventions are discussed, with a clinical emphasis on patient selection and prevention.

The Effects of Cilostazol on Peripheral Neuropathy in Diabetic Patients With Peripheral Arterial Disease

Background Evidence from diabetic animal models suggests that cilostazol, a cyclic AMP phosphodiesterase inhibitor used in the treatment of claudication, is efficacious in the treatment of peripheral neuropathy, although this is unproven in humans. The main aim of this study was to assess the effects of cilostazol on neuropathic symptomatology in diabetic patients with peripheral arterial disease (PAD). Methods Diabetic patients with PAD were prospectively recruited to a randomized double-blinded placebo-controlled trial. Baseline clinical data were recorded prior to trial commencement following medical optimization. Neurological assessment included the Toronto Clinical Neuropathy Scoring system (TCNS) and vibration perception thresholds (VPT) with a neurothesiometer at baseline, 6 weeks, and 24 weeks. Results Twenty-six patients were recruited from December 2004 to January 2006, which included 20 males. Baseline patient allocation to treatment arms was matched for age, sex, and medical comorbidities. There was no significant difference in neurological assessment between the treatment groups using the TCNS and VPT at 6 and 24 weeks. Conclusions Despite extensive animal-based evidence that cilostazol attenuates neuropathic symptomatology, our results do not support this effect in human diabetic PAD patients.

Peripheral and central neurologic complications in type 2 diabetes mellitus: No association in individual patients

Diabetes mellitus is associated with end-organ complications in the peripheral and central nervous system. It is unknown if these complications share a common aetiology, and if they co-occur in the same patient. The aim of the present study was to relate different measures of peripheral neuropathy in patients with type 2 diabetes mellitus (DM2) to cognition and brain MRI. A standardized neurological examination and questionnaire, neuropsychological examination and brain MRI were performed in 122 patients with DM2 and 56 matched controls. Measures of peripheral neuropathy were vibration threshold, a sensory examination sum score and the Toronto Clinical Neuropathy Scoring System. Neuropsychological test scores were expressed in standardized z-values across five predetermined cognitive domains. White matter lesions and cortical and subcortical atrophy were rated on MRI. Overall 38% of the patients with DM2 and 12% of the controls were classified as having any neuropathy (p<0.001). Patients with DM2 had a lower performance on the neuropsychological tests, more white matter lesions (p<0.01) and more atrophy (p<0.01) than controls. Within the DM2 group none of the measures of peripheral neuropathy was related to MRI abnormalities or cognitive dysfunction (linear regression analyses, adjusted for age, education, sex). We conclude that peripheral neuropathy in patients with DM2 is not related to cognitive dysfunction and brain abnormalities. This indicates that central and peripheral neurological complications of DM2 might have different etiologies.

[Prevalence of diabetic polyneuropathy in a rural population. Application of the Toronto Clinical Scoring System (TCSS)]

Objetivo

Determinar la prevalencia de polineuropatía periférica diabética (PNPDM) en nuestro medio.

Diseño

Estudio observacional, descriptivo, transversal.

Emplazamiento

Zona básica de salud (ZBS) de Porzuna, Ciudad Real.

Participantes

Todos los pacientes de la ZBS diagnosticados de diabetes mellitus en cualquiera de sus modalidades clínicas e independientemente del tiempo de evolución o edad del paciente, exceptuando los transeúntes o adscritos sólo de manera temporal a alguno de los cupos. Se excluyó del estudio a los pacientes con deterioro cognitivo lo suficientemente importante a juicio del investigador como para hacer inviable la anamnesis o la exploración necesaria.

Mediciones principales

Se registraron datos sobre antecedentes personales y familiares, comorbilidad, evolución de la diabetes (antigüedad, tratamiento, complicaciones), datos clínico-exploratorios (peso, talla, presión arterial, frecuencia cardíaca) y datos de laboratorio referentes a la diabetes. Para determinar la presencia de polineuropatía diabética (PNP-DM) se ha utilizado el Toronto Clinical Scoring System (Escala de Toronto [ET])1.

Resultados

Se identificó a 297 pacientes diabéticos (prevalencia del 5,51%), de los cuales 26 presentaban criterios de exclusión. El 96,7% eran diabéticos tipo 2, con una edad media de 68,6 ± 11,1 años y 9,7 ± 6,5 años de evolución. El 60,5% eran mujeres. Sus características se resumen en la tabla 1.

Tabla 1 Características generales de los pacientes diabéticos de la ZBS incluidos en el estudioParámetro n % Sexo  Varones 107 39,5%  Mujeres 164 60,5%  Edad (media ± DE) 68,6 ± 11,10 −  Tipo de DM  DM tipo 1 4 1,5%  DM tipo 2 262 96,7%  Otros 5 1,9% Años de evolución (media ± DE) 9,7 ± 6,5 (1-37) Edad de inicio (media ± DE) 58,9 ± 12,3 − Comorbilidad  HTA 194 71,6%  Obesidad 153 57,5%  Dislipemia 172 63,5%  Tabaquismo 21 7,7%  Patología tiroidea 20 7,4%  Cardiopatía isquémica 63 23,2%  ACV 19 7,0%  Arteriopatía periférica 17 6,3 Amputaciones 8 2,9% Presencia de complicaciones  Retinopatía DMa 61 22,5%  Nefropatía DMb 72 26,6%  Neuropatía DMc 6 2,2% Tratamiento de la DM  Dieta solo 46 17,0%  ADO 142 52,6%  ADO + insulina 48 17,8%  Insulina solo 34 12,6%  Peso (media ± DE) 78,2 ± 15,8 −  IMC (media ± DE) 31,4 ± 5,7 − Perímetro abdominal  Varones 105,1 ± 14 −  Mujeres 105,0 ± 13,9 − PAS (media ± DE) 152,4 ± 18,7 − PAD (media ± DE) 79,3 ± 10,2 − Glucemia basal (media ± DE) 158,6 ± 54,4 − HbA1c (media ± DE) 7,1 ± 1,6 − Creatinina (media ± DE) 0,9 ± 0,3 − TSH (media ± DE) 2,7 ± 5,4 − Rango de puntuación  < 6 (normal) 184 67,9%  6-8 (PNP-DM leve) 51 18,8%  9-11 (PNP-DM moderada) 30 11,1%  > 11 (PNP-DM grave) 6 2,2% ADO: antidiabéticos orales. aNo proliferativas, 72,1%; proliferativas 26,2%. bUsando la fórmula de Cockroft y Gault, de las cuales son leve el 58,3%, moderada el 34,7% y grave el 1,4%. cSegún informe de la historia clínica.

Los valores obtenidos en la ET muestran que un 32,1% de los pacientes presentaba algún grado de PNP-DM: leve (ET = 6-8) en el 18,8%, moderada (ET = 9-11) en el 11,1% y grave (ET > 11) en el 2,2%. La puntuación media del conjunto de diabéticos para dicha escala era de 3,9 ± 3,5. El grado de gravedad de la PNP-DM se acentúa con la edad (p = 0,0003) y las puntuaciones de PNP-DM grave no aparecen antes de los 60 años de edad; los pacientes con algún grado de polineuropatía llevan más años de evolución de su diabetes (10,7) que los pacientes sin polineuropatía (9,12), aunque sin alcanzar la significación estadística (p = 0,07); sin embargo, sí se encuentra significación estadística respecto a la edad de inicio clínico de la diabetes (según fecha registrada en la historia clínica: 62,2 frente a 57,4 años; p = 0,0028), el índice de masa corporal (IMC) (p = 0,0056), perímetro abdominal (p = 0,0008), la cifra de la velocidad de sedimentación globular (p = 0,002) y los diagnósticos de retinopatía diabética (p < 0,0001) o cardiopatía isquémica (p = 0,0003), rozando la significación estadística con la hipertensión arterial (p = 0,052) y la arteriopatía periférica (p = 0,0573).

Discusión y conclusiones

La prevalencia de la PNP-DM es mal conocida debido a la diversidad de métodos empleados en la captación de las muestras de pacientes y los criterios diagnósticos utilizados, con una oscilación en la literatura científica entre el 23 y el 49,5%2. En nuestro país no hemos encontrado ningún trabajo que aborde el problema con una base poblacional bien definida, no expuesta a sesgos de selección en función de la edad de los pacientes, el ámbito asistencial u otros. La prevalencia encontrada en nuestro estudio (32,1%) está alejada de la obtenida en otros estudios realizados en el ámbito de la atención primaria de nuestro país2-5 y más cercana a la de los estudios publicados del Reino Unido y Estados Unidos6 efectuados en un ámbito hospitalario.

Por otro lado, la ET para PNP-DM ha resultado ser rápida y fácil de aplicar, y en general muy bien tolerada por el paciente, requiriendo un instrumental fácilmente asequible para el médico de atención primaria (monofilamento, diapasón de 126 Hz y martillo de exploración), útil tanto para la exploración sistemática del paciente diabético con intención diagnóstica como para el seguimiento de la evolución de la posible sintomatología de su polineuropatía. Puede constituir, en nuestra opinión, una excelente herramienta para facilitar la aproximación diagnóstica a la PNP-DM.

Metabolic and vascular determinants of impaired cognitive performance and abnormalities on brain magnetic resonance imaging in patients with type 2 diabetes

AIMS/HYPOTHESIS

The determinants of cerebral complications of type 2 diabetes are unclear. The present study aimed to identify metabolic and vascular factors that are associated with impaired cognitive performance and abnormalities on brain MRI in patients with type 2 diabetes.

METHODS

The study included 122 patients and 56 controls. Neuropsychological test scores were divided into five cognitive domains and expressed as standardised z values. Brain MRI scans were rated for white matter lesions (WML), cortical and subcortical atrophy, and infarcts. Data on glucose metabolism, vascular risk factors and micro- and macrovascular disease were collected.

RESULTS

Patients with type 2 diabetes had more cortical (p < 0.001) and subcortical (p < 0.01) atrophy and deep WML (p = 0.02) than the control group and their cognitive performance was worse. In multivariate regression analyses within the type 2 diabetes group, hypertension (p < 0.05) and a history of vascular events (p < 0.01) were associated with worse cognitive performance, while statin use was associated (p < 0.05) with better performance. Retinopathy and brain infarcts on MRI were associated with more severe cortical atrophy (both p < 0.01) and statin use with less atrophy (p < 0.05). Insulin level and brain infarcts were associated with more severe WML and statin use with less severe WML (all p < 0.05).

CONCLUSIONS/INTERPRETATION

Type 2 diabetes is associated with modest impairments in cognition, as well as atrophy and vascular lesions on MRI. This 'diabetic encephalopathy' is a multifactorial condition, for which atherosclerotic (macroangiopathic) vascular disease is an important determinant. Chronic hyperglycaemia, hyperinsulinaemia and hypertension may play additional roles.

A detailed profile of cognitive dysfunction and its relation to psychological distress in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (DM2) is a common metabolic disorder. DM2 is associated with cognitive impairments, and with depressive symptoms, which occur in about one third of patients. In the current study we compared the cognitive profile and psychological well-being of 119 patients with DM2 (mean age: 66 +/- 6; mean duration: 9 +/- 6 years) with 55 age and education matched-control participants. Groups were compared on cognitive performance in five major cognitive domains, psychological wellbeing [assessed by Symptom Checklist (SCL)-90-R and the Beck Depression Inventory (BDI-II)] and abnormalities on brain MRI. We hypothesized an interrelationship between cognition, MRI abnormalities, and psychological well-being. DM2 patients performed significantly worse than controls on cognitive tasks, especially on tasks that required more mental efficiency, although the differences were modest (effect sizes Cohen d < .6). We speculate that DM2 patients have a diminished ability to efficiently process unstructured information. Patients with DM2 had significantly higher scores on the SCL-90-R (p < .001) and on the BDI-II (p < .001) and worse MRI ratings than controls, but psychological distress did not correlate with cognition, MRI ratings or biomedical characteristics. Contrary to our hypothesis, cognitive disturbances and psychological distress thus seem independent symptoms of the same disease.

A survey of self-reported outcome instruments for the foot and ankle

The information acquired from self-reported outcome instruments is useful only if there is evidence to support the interpretation of obtained scores. To properly interpret scores, there should be evidence for content validity, construct validity, reliability, and responsiveness. Evidence regarding score interpretation must also contain a description of the applicable test conditions, including information about the characteristics of subjects, timing of data collection, and construct of change. The objective of this review was to identify self-reported outcome instruments that have evidence to support their usefulness for assessingthe effect of treatment directed at individuals with foot and ankle-related pathologic conditions in an orthopaedic physical therapy setting. In addition, we provide specific information that will allow clinicians and researchers to select an appropriate instrument and properly interpret the obtained scores. Fourteen self-reported outcome instruments that met the objective of this review were identified. Five instruments, the Foot and Ankle Ability Measure, Foot Function index, Foot Health Status Questionnaire, Lower Extremity Function Scale, and Sports Ankle Rating System quality of life measure, satisfied all 4 categories of evidence (content validity, construct validity, reliability, and responsiveness) outlined herein.

Quantitative Assessment of Diabetic Peripheral Neuropathy with use of the Clanging Tuning Fork Test

OBJECTIVE

To describe the clanging tuning fork (CTF) test, a novel method for using the C 128-Hz tuning fork to test for diabetic peripheral neuropathy (DPN), to evaluate the accuracy and reproducibility of this technique, and to compare it with the 5.07 (10 g) Semmes-Weinstein monofilament test.

METHODS

To determine the mean and standard deviation for the CTF test, repeated measurements were taken on one toe of 12 patients with diabetes during one visit. After these tests, 30 randomly selected patients were tested on both feet, with right and left scores compared for reproducibility of the results. The scores of the CTF test were compared with the monofilament scores in 45 patients with diabetes. Presence of foot ulcers in 81 patients was correlated with both test scores.

RESULTS

The mean duration of vibration sensation was 10.2 seconds, with a standard deviation of +/-1.3 seconds. The Pearson correlation coefficient comparing the right and the left foot scores for the same patient was 0.947 (P<0.05). Among patients with 8 seconds or less of vibration perception, results of monofilament testing were abnormal only in those whose vibration perception was less than or equal to 4 seconds. Of 32 patients with vibration perception of 4 seconds or less, 50% had normal monofilament test scores, including 29% of 17 patients with absent vibratory sensation.

CONCLUSION

The CTF test is reproducible and accurate. It provides a quantitative assessment of DPN and can document severe neuropathy, even in the presence of a normal result with the 10-g monofilament test. The risk of foot ulcers, which is associated with diminished vibratory sensation, can therefore be detected earlier and more accurately with the CTF test. The CTF test should replace the 10-g monofilament test as the recommended technique for detection of DPN.

A study of the prevalence and risk factors of foot problems in a population of diabetic patients in cameroon

Foot problems are common in diabetic patients and are one of the most expensive chronic complications to treat. The authors sought to determine the prevalence and risk factors of the diabetic foot in a clinic population. In this cross-sectional study of 300 diabetic patients, the authors reviewed records, carried out an interview, and performed a meticulous foot examination with assessment of neuropathy (monofilaments and tuning fork) and ischemia (pulses). Foot lesions were classified according to Wagner grades. The prevalence of foot lesions was 13.0% (inpatients 25.6% and outpatients 11.1%). Diabetic neuropathy assessed using monofilaments was found in 81 patients (27.3%) (monofilaments). The prevalence of ischemia was 21.3% and deformity was 17.3%, whereas 37 patients (12.3%) had a previous history of foot lesions. Foot examination was done in 14.3% of patients, and 47% had a risky nail-trimming habit, whereas 22% wore ill-fitting shoes. The prevalence of diabetic foot lesions is high, and known risk factors are significantly present, especially poor foot care.

Development and validity testing of the neuropathy total symptom score-6: questionnaire for the study of sensory symptoms of diabetic peripheral neuropathy

OBJECTIVE

The aim of this study was to develop and validate a neuropathy sensory symptom scale, the Neuropathy Total Symptom Score-6 (NTSS-6), which evaluates individual neuropathy sensory symptoms in patients with diabetes mellitus (DM) and diabetic peripheral neuropathy (DPN) in clinical trials, with the intent of distinguishing a response to therapy.

METHODS

The NTSS-6 questionnaire was developed to evaluate the frequency and intensity of individual neuropathy sensory symptoms identified frequently by patients with DPN (ie, numbness and/or insensitivity; prickling and/or tingling sensation; burning sensation; aching pain and/or tightness; sharp, shooting, lancinating pain; and allodynia and/or hyperalgesia). The NTSS-6 was administered 8 times over a 1-year period to DPN patients. The NTSS-6's reliability (determined by internal consistency and test-retest reproducibility), construct validity, convergent validity, and minimally clinically important differences (MCIDs) were determined.

RESULTS

The NTSS-6 was administered to a total of 205 patients at 10 centers in the United States, Canada, Belgium, Germany, Hungary, Croatia, Slovenia, and the United Kingdom. Internal consistency was demonstrated at all 8 visits (Cronbach's alpha > 0.7). Test-retest reproducibility (intraclass correlation coefficient >0.9) was observed during the baseline period and at end point. Construct validity was demonstrated by statistically significant correlations between the NTSS-6 total score and the Neuropathy Symptoms and Change (NSC) score (r = 0.773-0.885, P < 0.001). Convergent validity was demonstrated by statistically significant correlations between the change in NTSS-6 total scores and the following: change in NSC scores (r = 0.519-0.708, P < 0.001); change in Neuropathy Impairment Score of the Lower Limbs and composite nerve function scores (r = 0.188-0.202, P < 0.007), and categories of the Clinical Global Impressions (r = 0.402, P < 0.001). The within- and between-groups MCIDs for the total NTSS-6 total scores were -1.26 and 0.97 points, respectively. The mean (SD) within-group MCID for all patients who improved on the Clinical Global Impression was -2.29 (3.4) points.

CONCLUSIONS

The NTSS-6 provided a valid assessment of neuropathy sensory symptoms in this sample of patients with DM and DPN, which suggests that it may be useful for symptom evaluation in clinical trials and practice. The NTSS-6 showed internal consistency, test-retest reliability, and construct validity. There was also convergent validity of the scores, indicating that the NTSS-6 may be a suitable questionnaire for clinical trials that evaluate symptoms of DPN in this well-defined patient population.

The prevalence, severity, and impact of painful diabetic peripheral neuropathy in type 2 diabetes

OBJECTIVE

To determine the prevalence of painful diabetic peripheral neuropathy (PDPN) in a population-based sample and to estimate its severity and impact.

RESEARCH DESIGN AND METHODS

A cross-sectional descriptive study consisting of two phases: phase 1, a postal survey to patients with type 2 diabetes (an initial screening questionnaire including one question about pain); phase 2, neurological history and examination using the Toronto Clinical Scoring System. Subjects with PDPN or mixed (PDPN and nonneuropathic) pain completed the Neuropathic Pain Scale and Neuroqol to assess severity and nature of the pain and impact on quality of life. Those without PDPN completed the Neuroqol only.

RESULTS

In phase 1, there was a 92.7% response (n = 326), with 208 (63.8%) subjects reporting pain. In phase 2, 269 (82.5%) subjects attended and 51 (19.0%) were found to have PDPN: 99 (36.8%) nonneuropathic pain, 20 (7.4%) mixed pain, and 99 (36.8%) no pain (PDPN prevalence 26.4%). Of those with PDPN, 80% stated that their pain was moderate or severe. Those affected had poorer quality of life than those with no pain (difference in mean scores 3.6 [95% CI 2.5-4.6%]) compared with those with nonneuropathic pain (1.7 [0.4-2.9%]). Both pain and neuropathy score were independently associated with quality of life, and subjects with PDPN had significantly higher neuropathy scores.

CONCLUSIONS

Our study showed a prevalence of PDPN of 26.4%. Having PDPN has a significant negative effect on quality of life, and increasing neuropathy is associated with an increasing risk of developing PDPN.

[Selection of risk and diagnosis in diabetic polyneuropathy. Validation of method of new systems]

INTRODUCTION

In a previous study we developed a specific algorithm, the polyneuropathy selection method (PSM) with 4 parameters (age, HDL-C, HbA1c, and retinopathy), to select patients at risk of diabetic polyneuropathy (DPN). We also developed a simplified method for DPN diagnosis: outpatient polyneuropathy diagnosis (OPD), with 4 variables (symptoms and 3 objective tests).

OBJECTIVES

To confirm the validity of conventional tests for DPN diagnosis; to validate the discriminatory power of the PSM and the diagnostic value of OPD by evaluating their relationship to electrodiagnosis studies and objective clinical neurological assessment; and to evaluate the correlation of DPN and pro-inflammatory status.

DESIGN

Cross-sectional, crossed association for PSM validation. Paired samples for OPD validation.

SETTING

Primary care in 3 counties.

PARTICIPANTS

Random sample of 75 subjects from the type-2 diabetes census for PSM evaluation. Thirty DPN patients and 30 non-DPN patients (from 2 DM2 sub-groups in our earlier study) for OPD evaluation.

METHODS

The gold standard for DPN diagnosis will be studied by means of a clinical neurological study (symptoms, physical examination, and sensitivity tests) and electrodiagnosis studies (sensitivity and motor EMG). Risks of neuropathy, macroangiopathy and pro-inflammatory status (PCR, TNF soluble fraction and total TGF-beta1) will be studied in every subject.

EXPECTED RESULTS

Electrodiagnosis studies should confirm the validity of conventional tests for DPN diagnosis. PSM and OPD will be valid methods for selecting patients at risk and diagnosing DPN. There will be a significant relationship between DPN and pro-inflammatory tests.

Brain magnetic resonance imaging correlates of impaired cognition in patients with type 2 diabetes

The structural correlates of impaired cognition in type 2 diabetes are unclear. The present study compared cognition and brain magnetic resonance imaging (MRI) between type 2 diabetic patients and nondiabetic control subjects and assessed the relationship between cognition and MRI findings and blood pressure and metabolic control. The study included 113 patients and 51 control subjects. Brain MRI scans were rated for white matter lesions (WMLs), cortical and subcortical atrophy, and infarcts. Neuropsychological test scores were divided into five cognitive domains and expressed as standardized Z values. Type 2 diabetes was associated with deep WMLs (P = 0.02), cortical (P < 0.001) and subcortical (P < 0.05) atrophy, (silent) infarcts (P = 0.06), and impaired cognitive performance (attention and executive function, information-processing speed, and memory, all P < 0.05). Adjustment for hypertension did not affect the results. Within the type 2 diabetic group, cognitive function was inversely related with WMLs, atrophy, and the presence of infarcts (adjusted for age, sex, and estimated IQ), and there was a modest association with HbA1c and diabetes duration. This association was strongest for age, even more so than in control subjects. We conclude that cognitive impairments in patients with type 2 diabetes are not only associated with subcortical ischemic changes in the brain, but also with increased brain atrophy.

Long-term effects of ranirestat (AS-3201) on peripheral nerve function in patients with diabetic sensorimotor polyneuropathy

OBJECTIVES

We aimed to determine whether ranirestat, an aldose reductase inhibitor, maintains the improved nerve function observed in patients with diabetic sensorimotor polyneuropathy (DSP) after completing a 12-week nerve biopsy study.

RESEARCH DESIGN AND METHODS

Patients with mild to moderate DSP, as determined by the presence of sural nerve responses, were enrolled in a double-blind, placebo-controlled biopsy trial and randomized to placebo or 5 or 20 mg/day ranirestat for 12 weeks. Patients completing this biopsy study were offered a 48-week extension at the same ranirestat dose or at 5 mg/day ranirestat if they were originally treated with placebo. Electrophysiological tests, the Toronto Clinical Neuropathy Score, and vibration perception thresholds (VPTs) were performed at entry and at 12 (end of the biopsy study) and 60 (end of the 48-week extension) weeks.

RESULTS

Peroneal motor nerve conduction velocity (NCV) improved in the 20-mg/day group following 60 weeks of treatment. Sural and median sensory NCV improved after both 12 and 60 weeks of treatment with 20 mg/day. VPT improved after 60 weeks of treatment with 20 mg/day. Ranirestat was well tolerated with no difference in adverse events between the 5- and 20-mg/day groups.

CONCLUSIONS

Twenty milligrams ranirestat per day improves NCV and VPT following 60 weeks of administration. The improved sensory nerve function observed after 12 weeks of therapy was maintained at 60 weeks, and improved motor nerve function was observed at 60 weeks.

Distal site testing of sympathetic skin response (big toe) in diabetic polyneuropathy

The aim of this study was to determine whether the sympathetic skin response (SSR) recorded from the big toe is more sensitive than standard SSR recorded from the sole for the detection of sudomotor fiber dysfunction in diabetic neuropathy. We recorded big toe SSR (SSRBT) and plantar SSR (SSRP) in 17 diabetic patients with non-disabling neuropathy (group A), 13 patients with disabling neuropathy (group B) and 30 age-matched normal controls. With regard to controls, SSRP amplitude was reduced only in group B. In contrast, SSRBT amplitude was reduced in both groups of patients (p<0.0001). In 8 patients in group B, SSRBT was not recordable while the SSRP still persisted. Our results suggest that SS-RBT is a more sensitive test than SSRP in detecting distal sudomotor failure in patients with diabetic neuropathy.

Aldose reductase inhibition in the treatment of diabetic neuropathy: where are we in 2004?

Diabetic neuropathy is a major complication of poorly controlled diabetes mellitus. Aldose reductase, the first enzyme of the polyol pathway, is thought to play a role in initiating the metabolic damage to peripheral nerves during hyperglycemia. Aldose reductase inhibitors (ARIs) have been proposed to dampen the flux of glucose through the pathway during hyperglycemia; however, clinical trials in diabetic patients to demonstrate efficacy in the prevention or amelioration of diabetic neuropathy have failed thus far. Recent improved understanding of the pitfalls of past trials and some improved ARIs and clinical evaluation instruments show promise that success in the 20-plus year search for efficacious ARIs may soon be at hand.

Aldose reductase inhibition by AS-3201 in sural nerve from patients with diabetic sensorimotor polyneuropathy

OBJECTIVE

The primary purpose of this investigation was to determine whether AS-3201, a new aldose reductase inhibitor, penetrates the sural nerve and inhibits sorbitol and fructose accumulation in patients with diabetic sensorimotor polyneuropathy (DSP). An additional aim was to determine whether any changes in nerve function would manifest with AS-3201 therapy.

RESEARCH DESIGN AND METHODS

Patients with mild to moderate DSP based on nerve conduction studies were randomized into one of three treatment groups in a double-blind fashion: placebo or AS-3201 at 5 or 20 mg/day. After 12 weeks of administration, the sural nerve was biopsied for measurement of sorbitol, fructose, and AS-3201.

RESULTS

At baseline, no important clinical, electrophysiological, or laboratory differences were found between the three groups. The nerve sorbitol concentration of 3.14 x 10(-2) nmol/mg wet nerve in patients in the placebo group was inhibited by 65 and 84% in patients on AS-3201 at 5 and 20 mg/day, respectively (P < 0.001). Fructose levels were similarly inhibited. Sensory nerve conduction velocities improved by > or = 1 m/s (P < 0.05).

CONCLUSIONS

AS-3201 penetrates the sural nerve and inhibits sorbitol accumulation in patients with DSP. Additional studies are needed to confirm the electrophysiological suggestion that AS-3201 delays progression or leads to regression of DSP.

Cooling detection thresholds in the assessment of diabetic sensory polyneuropathy: comparison of CASE IV and Medoc instruments

OBJECTIVE

Cooling detection threshold testing may be an important quantitative method for assessing polyneuropathy, in that it has traditionally been viewed as a measure of small-fiber involvement. The present study sought to determine the agreement between two common testing devices and to determine whether these are concordant in their association with predictor variables for diabetic sensory polyneuropathy.

RESEARCH DESIGN AND METHODS

A total of 83 patients with diabetes (10 patients with type 1 diabetes and 73 patients with type 2 diabetes) and a wide spectrum of diabetic sensory polyneuropathy severity underwent concurrent cooling detection threshold testing using the Medoc and CASE IV instruments. Common predictor variables for diabetic sensory polyneuropathy were measured on the same day.

RESULTS

Measurements of cooling detection thresholds by both instruments were highly correlated (Spearman's correlation coefficient 0.81, P < 0.001) and demonstrated a high degree of agreement by the method of Bland and Altman (95% distribution critical values for the difference in cooling detection thresholds, +7.5 and -5.6 degrees C). Cooling detection thresholds by both instruments were strongly correlated with clinical indicators of large-fiber neuropathy but not with the symptoms of small-fiber neuropathy (pain).

CONCLUSIONS

These two instruments available for assessment of cooling detection thresholds are interchangeable for research in diabetic sensory polyneuropathy. However, this modality is equivalent to other modalities of quantitative sensory threshold testing in its association with indicators of large-fiber neuropathy and does not seem to provide an advantage for the prediction of small-fiber involvement.

Diabetic neuropathy: a review emphasizing diagnostic methods

Diabetic sensorimotor polyneuropathy (DSP) is the most common complication of diabetes. In order to manage DSP effectively, it is necessary to formulate an accurate diagnosis and monitor subjects regularly. This review of important aspects of the diagnosis of DSP starts with a conceptual framework that includes elements of DSP epidemiology, pathophysiology, and therapy. The emphasis of the review is to present our current understanding of diagnostic methods for DSP including their utility and limitations. Screening for DSP in the diabetes clinic can be achieved successfully using simple clinical tests. Clinical neurophysiological methods are necessary to exclude other diagnoses, stage severity, and monitor the course of DSP. Novel investigative techniques are highly promising, but their usefulness in the clinic setting remains limited at this time. This article presents an overview of diagnostic methods for DSP.