A cross-sectional study of gender differences in quality of life domains in patients with neurofibromatosis type 1

BACKGROUND

There is limited data regarding gender differences in quality of life between women and men with Neurofibromatosis type 1. We aimed to study differences in quality of life domains between women and men with Neurofibromatosis type 1 living in Canada.

METHODS

This is a cross sectional study of adults with Neurofibromatosis type 1 attending a tertiary NF centre at Toronto General Hospital between January 2016 to December 2017. Demographic and clinical data were collected. We compared scores of generic measures (SF-36, EQ-5D-5L, pain interference) and a disease-specific measure (PedsQL-NF1 module) between women and men. We also assessed the relationship between disease visibility scored by an examiner (Ablon's visibility index) and self-reported perceived physical appearance, stratified by gender.

RESULTS

One hundred and sixty-two participants were enrolled, 92 females and 70 males. Ablon's index score 1 was in 43% and score 2 in 44%, while only 13% of patients had a score 3. Women had worse scores on the total PedsQL-NF1 scales, and also in the perceived physical appearance, anxiety and emotional health domains. In women, there was a low but significant correlation between Ablon's index and perceived physical appearance (r = - 0.27, p = 0.01, ANOVA p < 0.001). In men, there was no difference in self-reported physical appearance by Ablon's index. There were no differences between men and women in the SF-36 or EQ-5D-5L scores.

CONCLUSION

Women with NF1 reported worse NF1-related quality of life than men, with worse perceived physical appearance, anxiety, and mental health. Perceived physical appearance does not always correlate to disease visibility; therefore, healthcare providers should inquire about body image, physical appearance concerns, and mental health, especially among women with NF1.

Chronic immunoglobulin maintenance therapy in myasthenia gravis

BACKGROUND AND PURPOSE

Long-term treatment of myasthenia gravis (MG) includes symptomatic and course-modifying therapies that target the immune system. Recently, both intravenous immunoglobulin (IVIG) and subcutaneous immunoglobulin (SCIG) have emerged as viable options for chronic therapy, considering the favourable safety-efficacy profile and possible immunosuppressant sparing properties. The aim was to investigate the outcomes of the long-term care of generalized MG with immunoglobulin (Ig).

METHODS

This is a retrospective, repeated-measures design study. Charts of generalized MG patients, treated with IVIG/SCIG for at least 6 months, from January 2015 to January 2020, were analysed. The primary outcome was the mean change in Myasthenia Gravis Impairment Index (MGII) after treatment with Ig, comparing baseline to IVIG and SCIG treatment periods. Secondary outcomes included the changes in pyridostigmine, immunosuppressive medications and patient-reported outcome 'percentage of normal' (0%-100%).

RESULTS

Thirty-four patients were treated with chronic Ig therapy (30 IVIG/SCIG, three SCIG, one IVIG). The mean durations of IVIG and SCIG periods were 21.8 ± 19.4 (range 3-64) months and 19.5 ± 11.3 (range 5-45) months respectively. There was a significant reduction in MGII scores (27.7 ± 15.7 baseline; 22.0 ± 17.4 IVIG period; 19.5 ± 18.1 SCIG period; F = 17.9; d.f. = 1.7; P < 0.01), pyridostigmine and immunosuppressant use (P = 0.00). The outcome 'percentage of normal' had a significant positive association with both treatments (P = 0.00).

CONCLUSION

Our study results suggest that patients can be successfully transitioned to IVIG and from IVIG to SCIG in the chronic treatment of generalized MG with reductions in impairments and use of other medications and improvement in overall status with Ig therapy. Prospective, randomized studies are needed to clarify costs and comparative effectiveness.

Comparison of the single simple question and the patient acceptable symptom state in myasthenia gravis

BACKGROUND AND PURPOSE

The single simple question (SSQ) is a simple and validated question asking what percentage of normal a patient feels with respect to their myasthenia gravis (MG), with 100% being normal. Patient acceptable symptom states (PASS) are based on a dichotomous 'Yes' or 'No' response, asking whether a patient is satisfied overall with their current status and thus measures holistic satisfaction with their MG state. Both are patient-reported self-assessments but assess different dimensions of MG. The objective was to determine thresholds for the SSQ when patients with MG achieve an acceptable PASS status.

METHODS

A retrospective chart review was performed of consecutive MG patients attending a neuromuscular clinic, and SSQ and PASS responses, demographic, clinical and serological characteristics and disease severity by the MG impairment index were extracted.

RESULTS

One hundred and fifty-seven consecutive patients were identified: 43 (27.4%) patients responded 'No' to the PASS question. Between the PASS 'Yes'/'No' groups, only SSQ (87.5 ± 13.4 vs. 52.3 ± 23.3; P < 0.001) and MG impairment index scores (9.2 ± 10.3 vs. 29.6 ± 16; P < 0.001) were significantly different. The receiver operating characteristic curve for PASS and SSQ had an area under the curve of 0.92 ± 0.024 (confidence interval 0.872-0.965, P < 0.001). An SSQ score ≥72.5% had 84.2% sensitivity and 86% specificity to classify patients as PASS positive.

CONCLUSION

The PASS and SSQ patient-reported outcomes are closely associated and a SSQ threshold ≥72.5% predicts an acceptable MG state. Other demographic and disease-related factors did not influence the PASS response in this study.

Chronic stress, depression and personality type in patients with myasthenia gravis

BACKGROUND AND PURPOSE

Stress is a known risk factor for the onset and modulation of disease activity in autoimmune disorders. The aim of this cross-sectional study was to determine any associations between myasthenia gravis (MG) severity and chronic stress, depression and personality type.

METHODS

In all, 179 consecutive adult patients with confirmed MG attending the Neuromuscular Clinic between March 2017 and December 2017 were included. At baseline, patients were assessed clinically and they completed self-administered scales for disease severity, perceived stress, depression and personality type.

RESULTS

Higher disease severity [Myasthenia Gravis Impairment Index (MGII)] showed a moderate correlation with depression score (Beck's Depression Inventory, Second Edition, r = 0.52, P < 0.001) and a lower correlation with chronic stress (Trier Inventory for Assessment of Chronic Stress, r = 0.28, P = 0.001). Chronic stress scores were different according to personality types (anova, P = 0.02). The linear regression model with MGII score as the dependent variable showed R² = 0.34, likelihood ratio chi-squared 74.55, with P < 0.0001. The only variables that predicted disease severity were depression scores (P < 0.0001) and female sex (P = 0.003).

CONCLUSIONS

A significant association of MG severity with depression and chronic stress was found, as well as with female gender. These findings should raise awareness that the long-term management of MG should address depression and potential stress and consider behavioural management to prevent stress-related immune imbalance.

EQ-5D-5L and SF-6D health utility index scores in patients with myasthenia gravis

BACKGROUND AND PURPOSE

Health utilities are a preference-based method of valuing health states that are used in healthcare research, such as economic evaluations. There are limited health utility valuation data for patients with myasthenia gravis (MG). The aim of the study was to describe health utilities for patients with MG and different health states, using the EQ-5D-5L and SF-6D utility instruments, and to explore clinical and demographic determinants of utilities in this population.

METHODS

Patients completed the EQ-5D-5L and SF-6D. In addition, patients were assessed with the Myasthenia Gravis Foundation of America classification, Myasthenia Gravis Impairment Index and MG-QOL15 as disease-specific measures, and the Neuro-QoL Fatigue scale. We calculated mean utilities for each Myasthenia Gravis Foundation of America severity class. We built regression models for the EQ-5D-5L and SF-6D to determine the clinical and demographic factors that determine patients' valuation of their health state.

RESULTS

Among 254 patients, mean EQ-5D-5L health utilities were as follows: Remission, 0.94 ± 0.03; Minimal Manifestations, 0.92 ± 0.04; Class I, 0.89 ± 0.06; Class II, 0.78 ± 0.16; Class III, 0.58 ± 0.24 and Class IV, 0.61 ± 0.22. Mean SF-6D health utilities were as follows: Remission, 0.83 ± 0.07; Minimal Manifestations, 0.86 ± 0.14; Class I, 0.82 ± 0.14; Class II, 0.67 ± 0.12; Class III, 0.56 ± 0.11 and Class IV, 0.50 ± 0.10. The limb/axial scores were more highly correlated to health utilities than ocular or bulbar scores.

CONCLUSIONS

We present estimates of health utilities for patients with MG that can be used in cost-utility and decision analyses. Limb/axial symptoms had a higher impact on health utilities than ocular or bulbar symptoms, which might reflect the impact of mobility on health valuation.

Toronto Clinical Neuropathy Score is valid for a wide spectrum of polyneuropathies

BACKGROUND AND PURPOSE

The Toronto Clinical Neuropathy Score (TCNS) is a valid and reliable scale for the diagnosis and staging of diabetic sensorimotor polyneuropathy. In this study, we aimed to explore the performance of the TCNS in non-diabetic polyneuropathies.

METHODS

We performed a prospective study from November 2016 to May 2017 of patients with non-diabetic polyneuropathy. Patients had clinical, electrophysiological and functional assessments of their polyneuropathy, and the findings were correlated with the TCNS.

RESULTS

The TCNS correlated with all clinical, electrophysiological and disability measures of polyneuropathy, mostly at a moderate level (e.g. r = -0.58 for sural nerve action potential amplitude). Higher TCNS severity grades were associated with worse polyneuropathy on all measures in the lower limbs, and with worse electrophysiological parameters and vibration perception thresholds in the upper limbs. The scale also showed excellent reliability and accuracy (kappa, 0.92-0.93 for inter- and intra-observer reliability; area under the receiver operating characteristics curve, 0.93).

CONCLUSION

The TCNS is a valid and reliable scale for a wide spectrum of polyneuropathies, and might be useful in clinical practise and research for the diagnosis and staging of polyneuropathy.

Phenotyping animal models of diabetic neuropathy: a consensus statement of the diabetic neuropathy study group of the EASD (Neurodiab)

NIDDK, JDRF, and the Diabetic Neuropathy Study Group of EASD sponsored a meeting to explore the current status of animal models of diabetic peripheral neuropathy. The goal of the workshop was to develop a set of consensus criteria for the phenotyping of rodent models of diabetic neuropathy. The discussion was divided into five areas: (1) status of commonly used rodent models of diabetes, (2) nerve structure, (3) electrophysiological assessments of nerve function, (4) behavioral assessments of nerve function, and (5) the role of biomarkers in disease phenotyping. Participants discussed the current understanding of each area, gold standards (if applicable) for assessments of function, improvements of existing techniques, and utility of known and exploratory biomarkers. The research opportunities in each area were outlined, providing a possible roadmap for future studies. The meeting concluded with a discussion on the merits and limitations of a unified approach to phenotyping rodent models of diabetic neuropathy and a consensus formed on the definition of the minimum criteria required for establishing the presence of the disease. A neuropathy phenotype in rodents was defined as the presence of statistically different values between diabetic and control animals in 2 of 3 assessments (nocifensive behavior, nerve conduction velocities, or nerve structure). The participants propose that this framework would allow different research groups to compare and share data, with an emphasis on data targeted toward the therapeutic efficacy of drug interventions.

7(th) International Immunoglobulin Conference: Poster presentations

Immunoglobulin (Ig) therapy is the mainstay of treatment for primary antibody deficiency disorders and has proved to be efficacious in specific autoimmune and inflammatory diseases. Additionally, due to the role of Ig in complement activation, it is being used increasingly in solid organ transplantation. Furthermore, Ig is the primary or secondary treatment in some immune-mediated neuropathies such as chronic inflammatory demyelinating polyneuropathy (CIDP) or multifocal motor neuropathy (MMN). This session discusses trends of Ig use in Europe, proposed mechanisms of action, adverse effects and the potential role of Ig therapy in transplantation. Dr Šedivá reported that Ig therapy is available in all European countries, although dosing is not always optimal, due partly to reimbursement plans. Subcutaneous immunoglobulin (SCIg) has become increasingly accessible in recent years; however, the chosen route of administration still varies widely between countries. Dr Berger's presentation on optimization of Ig therapy in neuropathies, and Dr Rojavin's report on a pharmacometric model to determine the serum IgG levels achieved by different dosing regimens in primary antibody deficiency (PAD) patients, led to the challenging concept of using individualized dosing strategies. Dr Klehmet reported on the potential benefit of using antigen-specific T cell responses as a biomarker of IVIg responsiveness in CIDP patients, while Dr von Gunten provided an insight into the mechanisms of action of Ig preparations, suggesting that the immunoregulatory effects of IgG may be mediated by IgG antibodies against glycans. Dr Basta reported on the potential thrombogenic adverse effects associated with Ig therapy. Although these adverse events are rare, further studies are needed to clarify the relationship between Ig replacement and immunomodulatory therapy and these adverse reactions. In transplantation, Dr Carbone described that prophylactic IVIg treatment was found to decrease the incidence of severe infection in IgG hypogammaglobulinaemia patients undergoing heart transplantations. Furthermore, Dr Clatworthy reported that inactivating polymorphisms in the inhibitory receptor FcγRIIB do not impact upon kidney allograft survival.

7th International Immunoglobulin Conference: Poster presentations

The pan-European survey provides useful information on the accessibility and trends of intravenous and subcutaneous immunoglobulin (IVIg/SCIg) therapy, which is used to treat primary immunodeficiency disorders (PIDs). Although immunoglobulin (Ig) therapy is the first-line treatment for PIDs, the mechanisms of action of Ig therapy may differ according to the condition it is used to treat. Moreover, intriguing presentations suggest that further investigation is required to understand more clearly both the haematological and immunoregulatory effects of therapeutic immunoglobulin. This can ultimately provide more information on optimizing Ig therapy efficacy, and establish whether individualized dosing regimens for patients will be conducive to better clinical outcomes. In addition to treating autoimmune and inflammatory conditions, there is evidence to suggest that immunoglobulins can potentially play a role in transplantation, which warrants further investigation for future use.

Excessive Daytime Sleepiness in Patients with Myasthenia Gravis

Excessive daytime sleepiness (EDS) has not been investigated using objective tests in myasthenia gravis (MG). We investigated whether objective measurements of somnolence better detected abnormalities compared with sleepiness questionnaires in MG, and determine if MG patients have EDS. Eight patients with mild-to-moderate MG were recruited. Patients completed maintenance of wakefulness, overnight polysomnography, multiple sleep latency tests, Epworth Sleepiness Scale, and fatigue questionnaires. Seven patients demonstrated EDS on objective testing, while Epworth scores were abnormal in two, and the measures showed poor correlation. Our findings highlight that the ESS may be inadequate to diagnose EDS and lead to under-reporting of daytime somnolence in patients with MG.

Variables associated with corneal confocal microscopy parameters in healthy volunteers: implications for diabetic neuropathy screening

AIM

Corneal confocal microscopy is a promising screening method for diabetic neuropathy. Although much research in this field has been accomplished, we aimed to determine and confirm the known clinical and eyewear variables associated with the parameters of corneal confocal microscopy specifically in healthy volunteers, in particular associations with corneal nerve fibre length.

METHODS

Clinical characteristics, electrophysiological examination and a general clinical eye history were collected from 64 healthy volunteers. Corneal confocal microscopy was performed to determine corneal nerve fibre length, corneal nerve branch density, corneal nerve fibre density and tortuosity coefficient. Univariate and multivariate linear regression analysis was used to determine clinical variables associated with corneal nerve fibre length parameters.

RESULTS

We observed that corneal nerve fibre length has a broad distribution in healthy volunteers (18 ± 4 mm/mm(2), 95% confidence interval, 12.3-25.7 mm/mm(2)). Multivariate regression analysis demonstrated that HbA(1c) was the only independent clinical factor to account for variations in corneal nerve fibre length, independent of age and status of contact lens wear.

CONCLUSIONS

This study does not provide convincing evidence that corneal nerve fibre length is independently associated with age or the wearing of contact lenses, and that these factors are therefore unlikely to hinder valid screening for polyneuropathies such as diabetic neuropathy. Furthermore, the strong inverse association of corneal nerve fibre length with glycaemic exposure may support the use of this parameter to detect subclinical pre-diabetic nerve injury.

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.

Comparison of IVIg and PLEX in patients with myasthenia gravis

OBJECTIVE

Both IV immunoglobulin (IVIg) and plasma exchange (PLEX) are immunomodulatory treatments used to treat patients with myasthenia gravis (MG), but the choice of which treatment to administer to patients is limited due to lack of evidence from adequately powered, masked, randomized, standardized trials.

METHODS

We randomized 84 patients with moderate to severe MG defined as a Quantitative Myasthenia Gravis Score for disease severity (QMGS) of >10.5 and worsening weakness to IVIg (Gamunex®, Talecris Biotherapeutics) 1 g/kg/day for 2 consecutive days or PLEX (Caridian Spectra) 1.0 plasma volume exchanges for 5 exchanges. The patients were evaluated at day 14 after treatment for the primary efficacy parameter of change in QMGS and secondary clinical and electrophysiologic parameters and were followed for a total of 60 days.

RESULTS

Both IVIg and PLEX reduced the QMGS, and IVIg was comparable to PLEX in efficacy. The dropout rate was the same for both treatment arms and both treatments were well-tolerated. The presence of acetylcholine receptor antibodies and greater baseline disease severity predicted a better response to therapy. The postintervention status revealed that the same proportion of patients improved with treatment: 69% on IVIg and 65% on PLEX. The duration of improvement was similar with both treatments.

CONCLUSIONS

IVIg has comparable efficacy to PLEX in the treatment of patients with moderate to severe MG. Both treatments are well-tolerated, and the duration of effect is comparable. Either treatment may be offered to patients depending on availability of resources.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that IVIg and PLEX have comparable efficacy and are equally tolerated in adult patients with moderate to severe MG within 2 weeks of treatment.

Evidence-based guideline: Treatment of painful diabetic neuropathy: report of the American Academy of Neurology, the American Association of Neuromuscular and Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation

OBJECTIVE

To develop a scientifically sound and clinically relevant evidence-based guideline for the treatment of painful diabetic neuropathy (PDN).

METHODS

We performed a systematic review of the literature from 1960 to August 2008 and classified the studies according to the American Academy of Neurology classification of evidence scheme for a therapeutic article, and recommendations were linked to the strength of the evidence. The basic question asked was: "What is the efficacy of a given treatment (pharmacologic: anticonvulsants, antidepressants, opioids, others; and nonpharmacologic: electrical stimulation, magnetic field treatment, low-intensity laser treatment, Reiki massage, others) to reduce pain and improve physical function and quality of life (QOL) in patients with PDN?"

RESULTS AND RECOMMENDATIONS

Pregabalin is established as effective and should be offered for relief of PDN (Level A). Venlafaxine, duloxetine, amitriptyline, gabapentin, valproate, opioids (morphine sulfate, tramadol, and oxycodone controlled-release), and capsaicin are probably effective and should be considered for treatment of PDN (Level B). Other treatments have less robust evidence or the evidence is negative. Effective treatments for PDN are available, but many have side effects that limit their usefulness, and few studies have sufficient information on treatment effects on function and QOL.

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.

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.

A pilot study to compare the use of the Excorim staphylococcal protein immunoadsorption system and IVIG in chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune mediated neuropathy responding to immunomodulation with IVIG or plasma exchange (PE). We tested the efficacy and safety of selective immunoglobulin removal by Excorim immunoadsorption (IA) in a pilot trial in CIDP patients randomized to monthly IA or IVIG treatments for 6 months. Response rates at 2 and 6 months were greater with IA due to longer disease duration and greater disability at baseline in the patients receiving IVIG. IA appears to be a safe and efficacious therapy for patients with CIDP, but an appropriately powered clinical trial with stratification for disease duration is required.

Evaluation of three screening tests and a risk assessment model for diagnosing peripheral neuropathy in the diabetes clinic

OBJECTIVE

with the aim of evaluating predictive power, three simple screening tests as alternates to nerve conduction tests for diagnosing diabetic peripheral neuropathy (DPN) were investigated. Results of the screening tests, along with the subjects' demographic and clinical characteristics, were planned as the variables for the development of a risk assessment tool for predicting DPN.

DESIGN

this is a cross-sectional multi-group comparison study. The study utilized a predictive model derived from one subset of the study population, and prospectively tested in the other subset to predict the presence of neuropathy.

SETTING

Diabetic Neuropathy Research Clinic of the Toronto General Hospital and University Health Network in Toronto, Ontario, Canada from June 1998 to August 1999.

SAMPLE POPULATION

data come from 478 subjects consisting of non-diabetic reference subjects, and patients with type 1 and type 2 diabetes mellitus.

OUTCOMES MEASURES

nerve conduction studies (NCS) comprised the primary defined outcome. The three screening sensory tests examined in the study were the Semmes-Weinstein 10 g monofilament examination (SWME), superficial pain sensation, and vibration by the on-off method.

RESULTS

the three screening tests are significantly and positively correlated with NCS. An increase in the number of insensate responses in the screening test is associated with an increase in the abnormal NCS score. The strength of the association between NCS and each sensory test was greater when the neuropathy severity stage of the subject was added to the model. Both the SWME and vibration by the on-off method tests demonstrated sufficient statistical power to differentiate non-diabetic control subjects from subjects with diabetes, as well as to differentiate subjects with diabetes with and without neuropathy. These two tests, when compared with NCS, also demonstrated acceptable diagnostic performance characteristics in terms of high sensitivity and specificity, total number of correctly predicted cases, and receiver-operating characteristic curves.

CONCLUSION

this data, through the development of a model involving training and validation sets, demonstrates that the knowledge of clinical risk factors alters the interpretation of sensory tests for DPN. This finding lends further support to the validity of simple sensory testing maneuvers in the conditional diagnosis of DPN. We recommend annual screening with either the SWME or vibration by the on-off method in the primary care and diabetes clinics.

Status of current clinical trials in diabetic polyneuropathy

Peripheral polyneuropathy is the most frequent complication of diabetic mellitus. In spite of many clinical trials of different specific interventions for diabetic polyneuropathy, intensive glycemic control remains the only effective specific therapy currently available for this troublesome complication. This systematic overview reports the status of current clinical trials in diabetic polyneuropathy with an emphasis on those interventions directed towards specific pathophysiological derangements. A discussion of clinical trials of agents directed towards relieving painful symptoms of diabetic polyneuropathy concludes this overview.

Glycemic control is related to the morphological severity of diabetic sensorimotor polyneuropathy

OBJECTIVE

The aim of the current study was to determine the independent clinical risk factors for predicting morphological severity of distal diabetic sensorimotor polynecuropathy (DSP) as determined by fiber density (FD) on sural nerve biopsy.

RESEARCH DESIGN AND METHODS

A total of 89 patients with both type 1 and type 2 diabetes, ascertained from a large therapeutic randomized clinical trial, were included in this observational cohort study. Morphological severity of DSP was expressed as the myelinated FD in the sural nerve biopsy General linear models were used to assess the relationship between the morphological severity of DSP and various clinical risk factors.

RESULTS

Glycated hemoglobin (GHb) was significantly related to FD in univariate and multivariate regression analyses. This relationship was present in models in which GHb was handled either as a continuous variable or as a categorical variable with the highest significance level, with a GHb cutoff level of 9%. After dividing patients into groups with optimal to moderate GHb < or = 9%) and suboptimal (GHb >9%) glycemic control, the difference in FD between the two groups ranged between 3,461 and 2,334 per mm2. FD was also significantly related to duration of diabetes and age of the patient.

CONCLUSIONS

The severity of peripheral DSP expressed by morphological criteria was significantly related to glycemic control in type 1 and type 2 diabetic patients. Inconsistent with previously published electrophysiological data demonstrating a correlation between height and conduction velocity, increasing height is not associated with morphological severity. Based on the results of the present study, it might be hypothesized that improving glycemic control will lessen severity of DSP in terms of FD loss in subjects with diabetes.

Simple screening tests for peripheral neuropathy in the diabetes clinic

OBJECTIVE

The utility of rapid and reliable sensory tests appropriate for the diagnosis of neuropathy in the diabetes clinic, rather than as prognostic tools for the prediction of foot complications, has been unclear because of limitations inherent in previous studies. Although clinical practice guidelines recommend annual screening for neuropathy, they are unable to support specific recommendations for screening maneuvers because of a lack of evidence for the validity of screening tests in the medical literature. The objective of this study was to assess the operating characteristics of four simple sensory screening maneuvers as compared with standardized electrophysiological tests in the diagnosis of distal symmetrical polyneuropathy.

RESEARCH DESIGN AND METHODS

We assessed four simple tests (the 10-g Semmes-Weinstein monofilament examination [SWME], superficial pain sensation, vibration testing by the on-off method, and vibration testing by the timed method) in 478 subjects with independent blinded evaluations compared against the criterion standard of nerve conduction studies. We present receiver-operating characteristic (ROC) curves, positive and negative likelihood ratios, and sensitivity and specificity values for each test.

RESULTS

The four simple screening maneuvers reveal similar operating characteristics. Cutoff points by ROC curve analyses reveal that a positive or abnormal test is represented by five incorrect responses of eight stimuli applied. A negative or normal test is represented by one or fewer incorrect responses of eight stimuli applied. By these criteria, the point estimates of the positive likelihood ratios for vibration testing by the on-off method, vibration testing by the timed method, the SWME, and superficial pain sensation test are 26.6, 18.5, 10.2, and 9.2, respectively. The point estimates of the negative likelihood ratios are 0.33, 0.51, 0.34, and 0.50, respectively The screening tests showed comparable sensitivity and specificity results. The 10-g SWME, superficial pain test, and vibration testing by the on-off method are rapid, each requiring approximately 60 s to administer. The timed vibration test takes longer, and the interpretation is more complicated. The combination of two simple tests (e.g., the 10-g SWME and vibration testing by the on-off method) does not add value to each individual screening test.

CONCLUSIONS

Annual screening for diabetic neuropathy should be conducted using superficial pain sensation testing, SWME, or vibration testing by the on-off method. The reported operating characteristics for each sensory modality can be applied to positive findings on the physical examination of individual patients to predict the likelihood of neuropathy.

Heart rate variability measurement in diabetic neuropathy: review of methods

Heart rate variability (HRV) is an important tool to analyze the autonomic function. It therefore has a special interest for early detection and ensuing treatment of autonomic neuropathy in diabetic patients. The aim of this work is to present a brief historical review of HRV, as well as a technical review of the most common methods to measure it. In this work is presented a system that performs three measurements of HRV. An overview of methodologies developed to quantify HRV is presented; this technical review covers the most common time and frequency domain techniques, for short and long periods of time, with comments about clinical utility of these tests. A system performing three standard tests of HRV, Anscore Health Management System, is presented. This system performs metronomic breathing (MT), the Valsalva Test (VT), and the Stand Test (ST). A normal range study with 212 healthy subjects in three centers (ages 20-80 years, with even age distribution, and even male and female distribution) was conducted. A subset of 45 subjects from the total number of subjects was selected for the reproducibility study, consisting of three measurements of each test. The normal range study showed a decrease in all the ratios with age and, for the Valsalva test, a difference among genders; 5th percentiles were calculated. The reproducibility study results, expressed as mean CV%, were 4.30% for the MT, 6.26% for the VT, and 6.66% for the ST. HRV is the most reliable measurement of autonomic function; when controlled maneuvers like MT, VT, and ST are performed, high reproducibility is obtained, with results comparable to that observed for nerve conduction studies. Such reproducibility makes autonomic function testing more feasible as a test component in multicenter studies of different neurological disorders.

Sensory nerve area measurements in patients with diabetic neuropathy

Sensory nerve potential area measurements may reflect the properties of underlying nerve fibres better than amplitude or conduction velocity measures. The terminal segment of the sensory curve may contain activity of regenerating nerve fibres. The reliability of area measurements of sensory potentials obtained with surface recording techniques is unknown. We scanned sural nerve sensory potential curves and measured the areas under different parts of the curve in 52 reference and 73 diabetic polyneuropathy (DPN) patients. The variability of repeat testing in reference subjects for total area was 12% and for the terminal segmental area (TSA) was 19%. In DPN patients, the total area variability was 17% and TSA variability was 24%. This compares to amplitude variability of 8% in reference subjects and 10% in patients with DPN. These results demonstrate that sensory potential area measurements are feasible, but highly variable. We conclude that current clinical trials do not include sufficient numbers of patients to show change in area measurements, particularly the area under the terminal segment of the curve.

Limits of the sympathetic skin response in patients with diabetic polyneuropathy

We performed upper- and lower-limb sympathetic skin responses (SSRs) in a series of 337 diabetic patients with and without peripheral polyneuropathy and 38 reference subjects. We did not find any correlations between SSRs and symptoms of pain or autonomic dysfunction. The SSR correlated more strongly with vibration perception threshold (VPT) and sural nerve amplitude than with cooling detection threshold (CDT) or clinical symptoms. We conclude that current limitations inherent in SSR testing preclude its use as a reliable and consistent index of the autonomic dysfunction commonly encountered in diabetic patients.

NIS-LL: the primary measurement scale for clinical trial endpoints in diabetic peripheral neuropathy

Regulatory authorities favour the use of clinical endpoints, over surrogate endpoints, to demonstrate the efficacy of therapeutic agents for diabetic peripheral neuropathy (DPN). Progress in the quantification of the severity of DPN has been observed in recent years. The NIS-LL (Neuropathy Impairment Score in the Lower Limbs) is a new scale which quantifies the neurological function in DPN. This scale for determining the neuropathy impairment in DPN optimises the chances of demonstrating clinical change following pharmaceutical intervention in patients with early-stage neuropathy. The use of the NIS-LL in clinical trials, together with other tests measuring nerve function, pain and risk of foot ulcer, provides the best opportunity to evaluate the efficacy of new therapeutic agents for the treatment of DPN.

Impact of plasma exchange on indices of demyelination in chronic inflammatory demyelinating polyradiculoneuropathy

We studied the impact of plasma exchange (PE) on indices of primary demyelination in patients of the Canadian multicenter trial of PE in chronic inflammatory demyelinating polyneuropathy (CIDP). Individual motor nerves (median, ulnar, peroneal, tibial) were studied: distal motor latencies (DMLs), proximal and distal compound muscle action potential (M-wave) amplitudes, negative peak areas and durations, and motor conduction velocities (CVs). Proximal M-wave amplitudes in individual motor territories, particularly in the ulnar nerve (from below elbow, above elbow, and axillary stimulating sites) demonstrated significant improvement with PE, but not sham exchange. Proximal ulnar M-wave areas also had significant improvement with PE. Trends toward improvement of individual nerve motor CVs, M-wave durations, and DMLs did not achieve statistical significance. Proximal M-wave amplitudes, particularly in the ulnar motor territory, and proximal M-wave areas (providing a measure of conduction block) were the most sensitive indices of improvement conferred by PE in CIDP. In individual patients, these indices may help judge the efficacy of therapy.