Epineurial microvasculitis in proximal diabetic neuropathy

Clinical Reasoning: An Unusual Etiology of Lumbosacral Plexopathy in a Patient With HIV

We present a compelling case of uncontrolled diabetes, who initially presented as diabetic lumbosacral radiculoplexus neuropathy (DLRPN), with radicular pain in the right lower limb (LL) followed by asymmetric weakness of both LLs (right greater than left) with wasting in the medial compartment of the right thigh and significant sensory loss in the bilateral sural and right saphenous nerve distribution. Electrophysiology was suggestive of right lumbosacral radiculoplexus neuropathy. Incidentally, the patient tested positive for HIV-1 at our tertiary care center. CSF analysis revealed markedly elevated protein levels (>400 mg/dL) with lymphocytosis, a red flag for DLRPN. This observation led to further workup. Nerve biopsy showed large collections of perivascular endoneurial and epineurial lymphoid inflammatory cells, which favored an alternative diagnosis. This case highlights the intricate interplay between HIV infection, diabetes, and neurologic manifestations, challenging the initial clinical suspicion of DLRPN. This study emphasizes the importance of considering atypical presentations of neuropathy, especially in the context of coexisting medical conditions, and emphasizes the significance of comprehensive diagnostic workup, including CSF studies and nerve biopsy, for an accurate diagnosis.

Autoimmune polyneuropathies

The autoimmune peripheral neuropathies with prominent motor manifestations are a diverse collection of unusual peripheral neuropathies that are appreciated in vast clinical settings. This chapter highlights the most common immune-mediated, motor predominant neuropathies excluding acute, and chronic inflammatory demyelinating polyradiculoneuropathy (AIDP and CIDP, respectively). Other acquired demyelinating neuropathies such as distal CIDP and multifocal motor neuropathy will be covered. Additionally, the radiculoplexus neuropathies, resulting from microvasculitis-induced injury to nerve roots, plexuses, and nerves, including diabetic and nondiabetic lumbosacral radiculoplexus neuropathy and neuralgic amyotrophy (i.e., Parsonage-Turner syndrome), will be included. Finally, the motor predominant peripheral neuropathies encountered in association with rheumatological disease, particularly Sjögren's syndrome and rheumatoid arthritis, are covered. Early recognition of these distinct motor predominant autoimmune neuropathies and initiation of immunomodulatory and immunosuppressant treatment likely result in improved outcomes.

Risk factors for Lumbosacral Radiculoplexus Neuropathy

INTRODUCTION/AIMS

Recently, our group found an association between diabetes mellitus (DM) and lumbosacral radiculoplexus neuropathy (LRPN) in Olmsted County, Minnesota; we found a higher risk (OR: 7.91) for developing LRPN in diabetic compared to non-diabetic patients. However, the influence of other comorbidities and anthropomorphic variables was not studied.

METHODS

Demographic and clinical data from 59 LRPN patients and 177 age-sex matched controls were extracted using the Rochester LRPN epidemiological study. Differences between groups were compared by Chi-square/Fisher's exact test or Wilcox sum rank. Univariate and multivariate logistic regression analysis were performed.

RESULTS

Factors predictive of LRPN on univariate analysis were DM (OR 7.91; CI 4.11-15.21), dementia (OR 6.36; CI 1.13-35.67), stroke (OR 3.81; CI 1.32-11.01), dyslipidemia (OR 2.844; CI 1.53-5.27), comorbid autoimmune disorders (OR 2.72; CI 1.07-6.93), hypertension (OR 2.25; CI 1.2-4.13), obesity (OR 2.05; CI 1.11-3.8), BMI (OR 1.1; CI 1.04-1.15), and weight (OR 1.02; CI 1.009-1.037). On multivariate logistic regression analysis only DM (OR 8.03; CI 3.86-16.7), comorbid autoimmune disorders (OR 4.58; CI 1.45-14.7), stroke (OR 4.13; CI 1.2-14.25) and BMI (OR 1.07; CI 1.01-1.13) were risk factors for LRPN.

DISCUSSION

DM is the strongest risk factor for the development of LRPN, followed by comorbid auto-immune disorders, stroke and higher BMI. Altered metabolism and immune dysfunction seem to be the most influential factors in the development of LRPN. This article is protected by copyright. All rights reserved.

Immune mechanisms, the role of complement, and related therapies in autoimmune neuropathies

INTRODUCTION

Autoimmune neuropathies have diverse presentations and underlying immune mechanisms. Demonstration of efficacy of therapeutic agents that inhibit the complement cascade would confirm the role of complement activation.

AREAS COVERED

A review of the pathophysiology of the autoimmune neuropathies, to identify those that are likely to be complement mediated.

EXPERT OPINION

Complement mediated mechanisms are implicated in the acute and chronic neuropathies associated with IgG or IgM antibodies that target the Myelin Associated Glycoprotein (MAG) or gangliosides in the peripheral nerves. Antibody and complement mechanisms are also suspected in the Guillain-Barré syndrome and chronic inflammatory demyelinating neuropathy, given the therapeutic response to plasmapheresis or intravenous immunoglobulins, even in the absence of an identifiable target antigen. Complement is unlikely to play a role in paraneoplastic sensory neuropathy associated with antibodies to HU/ANNA-1 given its intracellular localization. In chronic demyelinating neuropathy with anti-nodal/paranodal CNTN1, NFS-155, and CASPR1 antibodies, myotonia with anti-VGKC LGI1 or CASPR2 antibodies, or autoimmune autonomic neuropathy with anti-gAChR antibodies, the response to complement inhibitory agents would depend on the extent to which the antibodies exert their effects through complement dependent or independent mechanisms. Complement is also likely to play a role in Sjogren's, vasculitic, and cryoglobulinemic neuropathies.

Lumbosacral Radiculoplexus Neuropathy: Neurologic Outcomes and Survival in a Population-Based Study

OBJECTIVE

To determine whether patients in the community with lumbosacral radiculoplexus neuropathy (LRPN) have milder neuropathy than referral patients, we characterized the outcomes and survival of population-based compared to referral-based LRPN cohorts.

BACKGROUND

Previously, we found that the incidence of LRPN is 4.16/100,000/y, a frequency greater than other inflammatory neuropathies. The survival of patients with LRPN is uncharacterized.

METHODS

Sixty-two episodes in 59 patients with LRPN were identified over 16 years (2000-2015). Clinical findings were compared to previous referral-based LRPN cohorts. Survival data were compared to those of age- and sex-matched controls.

RESULTS

At LRPN diagnosis, median age was 70 years, median Neuropathy Impairment Score (NIS) 22 points, 92% had pain, 95% had weakness, 23% were wheelchair-bound, and median modified Rankin Scale score (mRS) was 3 (range 1-4). At last follow-up, median NIS improved to 17 points (p < 0.001) with 56% having ≥4 points improvement, 16% were wheelchair-bound, and median mRS was 2. Compared to referral-based LRPN cohorts, community patients with LRPN had less impairment, less bilateral disease (37% vs 92%), and less wheelchair usage (23% vs 49%). LRPN survival was 86% at 5 years and 55% at 10 years. Compared to age- and sex-matched controls, patients with LRPN had 76% increased risk of death (p = 0.016). In multivariate analysis, diabetes, age, stroke, chronic kidney disease, peripheral artery disease, and coronary artery disease were significant mortality risk factors but LRPN was not.

CONCLUSION

LRPN is a painful, paralytic, asymmetric, monophasic, sometimes bilateral pan-plexopathy that improves over time but leaves patients with impairment. Although having LRPN increases mortality, this increase is probably due to comorbidities (diabetes) rather than LRPN itself.

Update on classification, epidemiology, clinical phenotype and imaging of the nonsystemic vasculitic neuropathies

PURPOSE OF REVIEW

Single-organ vasculitis of the peripheral nervous system (PNS) is often designated nonsystemic vasculitic neuropathy (NSVN). Several variants or subtypes have been distinguished, including migratory sensory neuropathy, postsurgical inflammatory neuropathy, diabetic radiculoplexus neuropathies, skin-nerve vasculitides, and, arguably, neuralgic amyotrophy. NSVN often presents as nondiabetic lumbosacral radiculoplexus neuropathy (LRPN). This review updates classification, clinical features, epidemiology, and imaging of these disorders.

RECENT FINDINGS

A recent study showed the annual incidence of LRPN in Olmstead County, Minnesota to be 4.16/100 000:2.79/100 000 diabetic and 1.27/100 000 nondiabetic. This study was the first to determine the incidence or prevalence of any vasculitic neuropathy. In NSVN, ultrasonography shows multifocal enlargement of proximal and distal nerves. In neuralgic amyotrophy, MRI and ultrasound reveal multifocal enlargements and focal constrictions in nerves derived from the brachial plexus. Histopathology of these chronic lesions shows inflammation and rare vasculitis. Diffusion tensor imaging of tibial nerves in NSVN revealed decreased fractional anisotropy in one study.

SUMMARY

Single-organ PNS vasculitides are the most common inflammatory neuropathies. Neuralgic amyotrophy might result from PNS vasculitis, but further study is necessary. The usefulness of focal nerve enlargements or constrictions in understanding pathological mechanisms, directing biopsies, and monitoring disease activity in NSVN should be further investigated.

Diabetic Amyotrophy: From the Basics to the Bedside

Diabetic amyotrophy is a rare complication of diabetes compared to distal symmetric polyneuropathy, but can occasionally be encountered in clinical practice, particularly as the incidence of diabetes increases. The distinctive history of unilateral neuropathic symptoms followed rapidly by atrophy and weakness is typical of the disorder. This complication most commonly occurs in cases of well-controlled Type 2 diabetes mellitus. While the underlying pathophysiology is known to be microvasculitic in nature, the diagnosis is often based on clinical and electrodiagnostic grounds and tissue biopsy is not typically performed. Attempts at corticosteroid administration during immunotherapy should be carefully considered on a patient-by-patient basis. Better recognition of this disorder is likely to result in more rapid diagnosis, counselling, and subspecialty referral.

Lumbosacral radiculoplexus neuropathy: Incidence and the association with diabetes mellitus

OBJECTIVE

To determine the previously unknown incidence of lumbosacral radiculoplexus neuropathy (LRPN) and its association with diabetes mellitus (DM).

METHODS

LRPN defined by clinical and electrophysiologic criteria was identified among Olmsted County, Minnesota, residents during a 16-year period (2000-2015) using the unique facilities of the Rochester Epidemiology Project. DM was ascertained using American Diabetes Association criteria.

RESULTS

Of 1,892 medical records reviewed, 59 patients (33 men, 26 women) were identified as having LRPN. The median age was 70 years (range 24-88 years) and the median time of onset of symptoms to diagnosis was 2 months (range 1-72 months). DM was more frequent in patients with LRPN than in controls (39/59 vs 35/177, p < 0.001) but not in those with pre-DM (10/20 vs 55/142, p = 0.336). LRPN recurred in 3 patients with DM resulting in 62 LRPN episodes during the study period. The overall incidence of LRPN was 4.16/100,000/y (95% confidence interval [CI] 3.13-5.18). The incidences of LRPN among DM and non-DM groups were 2.79/100,000/y (95% CI 1.94-3.64) and 1.27/100,000/y (95% CI 0.71-1.83), respectively. The odds of LRPN among patients with DM and pre-DM was 7.91 (95% CI 4.11-15.21) and 1.006 (95% CI 1.004-1.012), respectively.

CONCLUSIONS

LRPN incidence in Olmsted County of 4.16/100,000/y makes LRPN a common inflammatory neuropathy and is higher than that of other immune-mediated neuropathies (acute or chronic inflammatory demyelinating polyradiculoneuropathy, brachial plexus neuropathy) assessed within the same population. DM is a major risk factor for LRPN and thus justifies the continued classification of LRPN into diabetic and nondiabetic forms.

Diabetic Microvascular Disease: An Endocrine Society Scientific Statement

Both type 1 and type 2 diabetes adversely affect the microvasculature in multiple organs. Our understanding of the genesis of this injury and of potential interventions to prevent, limit, or reverse injury/dysfunction is continuously evolving. This statement reviews biochemical/cellular pathways involved in facilitating and abrogating microvascular injury. The statement summarizes the types of injury/dysfunction that occur in the three classical diabetes microvascular target tissues, the eye, the kidney, and the peripheral nervous system; the statement also reviews information on the effects of diabetes and insulin resistance on the microvasculature of skin, brain, adipose tissue, and cardiac and skeletal muscle. Despite extensive and intensive research, it is disappointing that microvascular complications of diabetes continue to compromise the quantity and quality of life for patients with diabetes. Hopefully, by understanding and building on current research findings, we will discover new approaches for prevention and treatment that will be effective for future generations.

Immunotherapy for diabetic amyotrophy

BACKGROUND

People with diabetes mellitus (DM) sometimes present with acute or subacute, progressive, asymmetrical pain and weakness of the proximal lower limb muscles. The various names for the condition include diabetic amyotrophy, diabetic lumbosacral radiculoplexus neuropathies, diabetic femoral neuropathy or Bruns-Garland syndrome. Some studies suggest that diabetic amyotrophy may be an immune-mediated inflammatory microvasculitis causing ischaemic damage of the nerves. Immunotherapies would therefore be expected to be beneficial. This is the second update of a review first published in 2009.

OBJECTIVES

To review the evidence from randomised trials for the efficacy of any form of immunotherapy in the treatment of diabetic amyotrophy.

SEARCH METHODS

On 5 September 2016 we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE and Embase. We also contacted authors of relevant publications and other experts to obtain additional references, unpublished trials, and ongoing trials.

SELECTION CRITERIA

We intended to include all randomised and quasi-randomised trials of any immunotherapy in participants with the condition fulfilling all the following: diabetes mellitus as defined by internationally recognised criteria; acute or subacute onset of pain and lower motor neuron weakness involving predominantly the proximal muscles of the lower limbs; weakness that is not confined to one nerve or nerve root distribution; and exclusion of other causes of lumbosacral radiculopathies and plexopathy.

DATA COLLECTION AND ANALYSIS

Two authors independently examined all references retrieved by the search to select those meeting the inclusion criteria.

MAIN RESULTS

We found only one completed placebo-controlled trial (N = 75) using intravenous methylprednisolone in diabetic amyotrophy (Dyck 2006). The results have not been fully published and were not available for analysis. The risk of bias was unclear because there was too little information to make a judgement, but we considered the trial at high risk of selective reporting. The published abstract did not report adverse events. We found no additional trials when the searches were updated in September 2016.

AUTHORS' CONCLUSIONS

There is presently no evidence from randomised trials to support a positive or negative effect of any immunotherapy in the treatment in diabetic amyotrophy.

Entrapment neuropathies in diabetes mellitus

Neuropathy is a common complication of diabetes mellitus (DM) with a wide clinical spectrum that encompasses generalized to focal and multifocal forms. Entrapment neuropathies (EN), which are focal forms, are so frequent at any stage of the diabetic disease, that they may be considered a neurophysiological hallmark of peripheral nerve involvement in DM. Indeed, EN may be the earliest neurophysiological abnormalities in DM, particularly in the upper limbs, even in the absence of a generalized polyneuropathy, or it may be superimposed on a generalized diabetic neuropathy. This remarkable frequency of EN in diabetes is underlain by a peculiar pathophysiological background. Due to the metabolic alterations consequent to abnormal glucose metabolism, the peripheral nerves show both functional impairment and structural changes, even in the preclinical stage, making them more prone to entrapment in anatomically constrained channels. This review discusses the most common and relevant EN encountered in diabetic patient in their epidemiological, pathophysiological and diagnostic features.

Morphometric analysis of connective tissue sheaths of sural nerve in diabetic and nondiabetic patients

One of the most common complications of diabetes mellitus is diabetic neuropathy. It may be provoked by metabolic and/or vascular factors, and depending on duration of disease, various layers of nerve may be affected. Our aim was to investigate influence of diabetes on the epineurial, perineurial, and endoneurial connective tissue sheaths. The study included 15 samples of sural nerve divided into three groups: diabetic group, peripheral vascular disease group, and control group. After morphological analysis, morphometric parameters were determined for each case using ImageJ software. Compared to the control group, the diabetic cases had significantly higher perineurial index (P < 0.05) and endoneurial connective tissue percentage (P < 0.01). The diabetic group showed significantly higher epineurial area (P < 0.01), as well as percentage of endoneurial connective tissue (P < 0.01), in relation to the peripheral vascular disease group. It is obvious that hyperglycemia and ischemia present in diabetes lead to substantial changes in connective tissue sheaths of nerve, particularly in peri- and endoneurium. Perineurial thickening and significant endoneurial fibrosis may impair the balance of endoneurial homeostasis and regenerative ability of the nerve fibers. Future investigations should focus on studying the components of extracellular matrix of connective tissue sheaths in diabetic nerves.

Diabetic radiculoplexus neuropathies

Diabetic radiculoplexus neuropathies (DRPN) are neuropathies clinically and pathologically distinct from the neuropathy typically associated with diabetes (DPN). DRPN are usually subacute in onset, painful, and often demonstrate a monophasic course with incomplete recovery. Pathologically, these neuropathies are due to ischemic injury from altered immunity and often have features suggestive or diagnostic of microvasculitis. Unlike DPN, immune therapy may be helpful in treatment of these conditions given their pathological substrate and therefore are important to identify early and distinguish from other neuropathies that occur in patient with diabetes.

Diabetic cervical radiculoplexus neuropathy: a distinct syndrome expanding the spectrum of diabetic radiculoplexus neuropathies

Diabetic lumbosacral radiculoplexus neuropathy is a subacute painful, asymmetrical lower limb neuropathy due to ischaemic injury and microvasculitis. The occurrence of a cervical diabetic radiculoplexus neuropathy has been postulated. Our objective was to characterize the clinical features and pathological alterations of diabetic cervical radiculoplexus neuropathy, to see if they are similar to diabetic lumbosacral radiculoplexus neuropathy and due to ischaemic injury and microvasculitis. We identified patients with diabetic cervical radiculoplexus neuropathy by review of the Mayo Clinic database from 1996 to 2008. We systematically reviewed the clinical features, laboratory studies, neurophysiological findings, neuroimaging and pathological features and compared the findings with a previously published diabetic lumbosacral radiculoplexus neuropathy cohort. Eighty-five patients (56 males, 67 with Type 2 diabetes mellitus) were identified. The median age was 62 years (range 32-83). The main presenting symptom was pain (53/85). At evaluation, weakness was the most common symptom (84/85), followed by pain (69/85) and numbness (56/85). Neuropathic deficits were moderate (median motor neuropathy impairment score 10.0 points) and improved at follow-up. Upper, middle and lower brachial plexus segments were involved equally and pan-plexopathy was not unusual (25/85). Over half of patients (44/85) had at least one additional body region affected (30 contralateral cervical, 20 lumbosacral and 16 thoracic) as is found in diabetic lumbosacral radiculoplexus neuropathy. Recurrent disease occurred in 18/85. Neurophysiology showed axonal neuropathy (80/80) with paraspinal denervation (21/65), and abnormal autonomic (23/24) and sensory testing (10/13). Cerebrospinal fluid protein was elevated (median 70 mg/dl). Magnetic resonance imaging showed brachial plexus abnormality in all (38/38). Nerve biopsies (11 upper and 11 lower limbs) showed ischaemic injury (axonal degeneration, multifocal fibre loss 15/22, focal perineurial thickening 16/22, injury neuroma 5/22) and increased inflammation (epineural perivascular inflammation 22/22, haemosiderin deposition 6/22, vessel wall inflammation 14/22 and microvasculitis 5/22). We therefore conclude that (i) diabetic cervical radiculoplexus neuropathy is a predominantly monophasic, upper limb diabetic neuropathy with pain followed by weakness and involves motor, sensory and autonomic fibres; (ii) the neuropathy begins focally and often evolves into a multifocal or bilateral condition; (iii) the pathology of diabetic cervical radiculoplexus neuropathy demonstrates ischaemic injury often from microvasculitis; and (iv) diabetic cervical radiculoplexus neuropathy shares many of the clinical and pathological features of diabetic lumbosacral radiculoplexus neuropathy, providing evidence that these conditions are best categorized together within the spectrum of diabetic radiculoplexus neuropathies.

Vasculitic neuropathy

Vasculitis is a primary phenomenon in autoimmune diseases such as polyarteritis nodosa, Wegener's granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, and essential mixed cryoglobulinemia. As a secondary feature vasculitis may complicate, for example, connective tissue diseases, infections, malignancies, and diabetes. Vasculitic neuropathy is a consequence of destruction of the vessel wall and occlusion of the vessel lumen of small epineurial arteries. Sometimes patients present with nonsystemic vasculitic neuropathy, i.e., vasculitis limited to peripheral nerves and muscles with no evidence of further systemic involvement. Treatment with corticosteroids, sometimes in combination with other immunosuppressants, is required to control the inflammatory process and prevent further ischemic nerve damage.

Diabetic neuropathy

Diabetes is the most common cause of peripheral neuropathy in the world. Both type 1 (insulin-dependent) and type 2 diabetes are commonly complicated by peripheral nerve disorders. Two main types of neuropathy are observed: the most common is a nerve fiber length-dependent, distal symmetrical sensory polyneuropathy with little motor involvement but frequent, and potentially life threatening, autonomic dysfunction. Alteration of temperature and pain sensations in the feet is an early manifestation of diabetic polyneuropathy. The second pattern is a focal neuropathy, which more commonly complicates or reveals type 2 diabetes. Poor diabetic control increases the risk of neuropathy with subsequent neuropathic pains and trophic changes in the feet, which can be prevented by education of patients.

Treatments for diabetic neuropathy

Diabetic neuropathy comprises disorders of peripheral nerve in diabetes patients after exclusion of other disorders and can be focal or diffuse. The focal diabetic neuropathies tend to resolve spontaneously and are treated by reassurance, physiotherapy and analgesia for painful symptoms. Diabetic sensorimotor polyneuropathy (DSP) is the most frequent form of diabetic neuropathy and effective disease-modifying treatment is not available beyond the interventions of optimal glycemic control, and possibly lifestyle and risk factor modification. In contrast, a recent evidence-based guideline shows that effective treatments for painful DSP include: pregabalin, amitriptyline, duloxetine, venlafaxine, gabapentin, opioids, nitrate sprays, capsaicin, and transcutaneous electrical nerve stimulation. The choice of treatment is guided by the clinical status of the individual patient.

Immunotherapy for diabetic amyotrophy

BACKGROUND

People with diabetes mellitus (DM) sometimes present with acute or subacute, progressive, asymmetrical pain and weakness of the proximal lower limb muscles. The various names for the condition include diabetic amyotrophy or diabetic lumbosacral radiculoplexus neuropathies. Some studies suggest that it may be due to immune-mediated inflammatory microvasculitis causing ischaemic damage of the nerves. Immunotherapies would therefore be expected to be beneficial. This is an update of a review first published in 2009.

OBJECTIVES

We aimed to review the evidence from randomised trials for the efficacy of any form of immunotherapy in the treatment of diabetic amyotrophy.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (7 February 2012), CENTRAL (2012 Issue 1), MEDLINE (January 1966 to January 2012) and EMBASE (January 1980 to January 2012), and contacted authors of relevant publications and other experts to obtain additional references, unpublished trials, and ongoing trials.

SELECTION CRITERIA

We intended to include all randomised and quasi-randomised trials of any immunotherapy in participants with the condition fulfilling all the following: diabetes mellitus as defined by internationally recognised criteria, acute or subacute onset of pain and lower motor neuron weakness involving predominantly the proximal muscles of the lower limbs, weakness that is not confined to one nerve or nerve root distribution and exclusion of other causes of lumbosacral radiculopathies and plexopathy.

DATA COLLECTION AND ANALYSIS

Two authors independently examined all references retrieved by the search to select those meeting the inclusion criteria.

MAIN RESULTS

We found only one completed controlled trial using intravenous methylprednisolone in diabetic amyotrophy (Dyck 2006). The results have not been fully published and were not available for analyses. We found no additional trials when the searches were updated in 2012.

AUTHORS' CONCLUSIONS

There is presently no evidence from randomised trials to support any recommendation on the use of any immunotherapy treatment in diabetic amyotrophy.

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.

Update on the management of diabetic polyneuropathies

The prevalence of diabetic polyneuropathy (DPN) can approach 50% in subjects with longer-duration diabetes. The most common neuropathies are generalized symmetrical chronic sensorimotor polyneuropathy and autonomic neuropathy. It is important to recognize that 50% of subjects with DPN may have no symptoms and only careful clinical examination may reveal the diagnosis. DPN, especially painful diabetic peripheral neuropathy, is associated with poor quality of life. Although there is a better understanding of the pathophysiology of DPN and the mechanisms of pain, treatment remains challenging and is limited by variable efficacy and side effects of therapies. Intensification of glycemic control remains the cornerstone for the prevention or delay of DPN but optimization of other traditional cardiovascular risk factors may also be of benefit. The management of DPN relies on its early recognition and needs to be individually based on comorbidities and tolerability to medications. To date, most pharmacological strategies focus upon symptom control. In the management of pain, tricyclic antidepressants, selective serotonin noradrenaline reuptake inhibitors, and anticonvulsants alone or in combination are current first-line therapies followed by use of opiates. Topical agents may offer symptomatic relief in some patients. Disease-modifying agents are still in development and to date, antioxidant α-lipoic acid has shown the most promising effect. Further development and testing of therapies based upon improved understanding of the complex pathophysiology of this common and disabling complication is urgently required.

Treatment of diabetic and nondiabetic lumbosacral radiculoplexus neuropathy

OPINION STATEMENT

Lumbosacral radiculoplexus neuropathy (LRPN) is a multifocal, asymmetric, painful neuropathic disorder affecting multiple levels of lumbosacral plexus, nerve roots, and distal nerves that emerge from the plexus. The disorder was first described in diabetic patients (DLRPN) and was later found to occur in nondiabetic patients as well. There have been debates as to the pathogenesis of DLRPN and LRPN. Recent detailed and extensive pathologic studies, however, have shown that the main pathogenesis is inflammation and microvasculitis affecting various components in the peripheral nerves, resulting in ischemic injury to the nerves. Even though studies on the natural history of this disorder have shown that the majority of patients recover within a few years after the attack without any treatment (although recovery is incomplete in many cases), it is a common practice, based on the pathophysiology and case series, to administer immunotherapy. Preliminary data from a controlled clinical trial failed to show significant improvement in outcomes measured by neurologic deficits (as judged by the Neuropathy Impairment Score) but did show improvement in symptoms (pain and positive sensory symptoms). Choices of immunotherapy include corticosteroids, intravenous immunoglobulin, plasma exchange, or a combination. Pain management, physical therapy, and treatment of depression remain mainstays for managing this disorder.

Painless diabetic motor neuropathy: a variant of diabetic lumbosacral radiculoplexus Neuropathy?

OBJECTIVE

Occasionally, diabetic patients develop painless, lower-limb, motor predominant neuropathy. Whether this is a variant of diabetic lumbosacral radiculoplexus neuropathy (DLRPN) (a painful disorder from ischemic injury and microvasculitis), a variant of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) or another disorder is unsettled. Here, we characterize the clinical and pathological features of painless diabetic motor predominant neuropathy.

METHODS

We identified patients with this syndrome who underwent nerve biopsy. We compared pathological features to 33 DLRPN and 25 CIDP biopsies.

RESULTS

23 patients were identified (22 had type 2 diabetes mellitus); 12 men; median age 62.2 years (range 36-78); median weight loss 30 pounds (range 0-100). Overall, the clinical features were similar to DLRPN except painless patients had more symmetrical and upper limb involvement, with slower progression and more severe impairment. Physiological testing demonstrated pan-modality sensory loss, autonomic abnormalities and axonal polyradiculoneuropathies. Nerve biopsies were similar to DLPRN showing ischemic injury (multifocal fiber loss [11/23], perineural thickening [18/23], injury neuroma [11/23], neovascularization [17/23]) and evidence of altered immunity and microvasculitis (epineurial perivascular inflammation [23/23], prior bleeding [11/23], vessel wall inflammation [15/23], and microvasculitis [3/23]). In contrast, CIDP biopsies did not show ischemic injury or microvasculitis but revealed demyelination and onion-bulbs.

INTERPRETATION

1) Painless diabetic motor neuropathy is painless DLRPN and not CIDP and is caused by ischemic injury and microvasculitis. 2) The clinical features of painless DLRPN are different from typical DLPRN being more insidious and symmetrical with slower evolution. 3) The slower evolution may explain the lack of pain.

Nerve biopsy: requirements for diagnosis and clinical value

In many instances, nerve biopsy is not necessary in the diagnostic work-up of a peripheral neuropathy. However, histological examination of a tissue sample is still mandatory to show specific lesions in various conditions involving peripheral nerves. As there are fewer laboratories that examine human nerve samples, practitioners including neurologists and general pathologists may not be completely aware of the technical issues and data that are provided by nerve biopsy. Nerve biopsy is considered an invasive diagnostic method, although, its complications are by far less disabling than most of the disorders that lead to its indications. Nevertheless, the decision to perform a nerve biopsy has to be made on a case-by-case basis, and its results must be discussed between the pathologist and the clinician who is in charge of the patient's care. In this paper, we review the minimal technical requirements for proper peripheral nerve tissue analysis. Moreover, we provide data on the usefulness of nerve biopsy in various situations including abnormal deposits, cell infiltrates, link between peripheral neuropathy and monoclonal gammopathy, and numerous hereditary disorders.

Immunotherapy for diabetic amyotrophy

BACKGROUND

People with diabetes mellitus (DM) sometimes present with acute or subacute, progressive, asymmetrical pain and weakness of the proximal lower limb muscles. The various names for the condition include diabetic amyotrophy, or diabetic lumbosacral radiculoplexus neuropathies. Some studies suggest that it may be due to immune-mediated inflammatory microvasculitis causing ischaemic damage of the nerves. Immunotherapies would therefore be expected to be beneficial.

OBJECTIVES

We aimed to review the evidence from randomised trials for the efficacy of any form of immunotherapy in the treatment of diabetic amyotrophy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register (searched April 2 2009), MEDLINE (searched January 1966 to April 2 2009), EMBASE (searched January 1980 to April 2 2009) and contacted authors of relevant publications and other experts to obtain additional references, unpublished trials, and ongoing trials.

SELECTION CRITERIA

We intended to include all randomised and quasi-randomised trials of any immunotherapy in participants with the condition fulfilling all the following: diabetes mellitus as defined by internationally recognised criteria, acute or subacute onset of pain and lower motor neuron weakness involving predominantly the proximal muscles of the lower limbs, weakness that is not confined to one nerve or nerve root distribution and exclusion of other causes of lumbosacral radiculopathies and plexopathy.

DATA COLLECTION AND ANALYSIS

Two authors independently examined all references retrieved by the search to select those meeting the inclusion criteria.

MAIN RESULTS

We found only one completed controlled trial using intravenous methylprednisolone in diabetic amyotrophy (Dyck 2006). The results have not been fully published and were not available for analyses.

AUTHORS' CONCLUSIONS

There is presently no evidence from randomised trials to support any recommendation on the use of any immunotherapy treatment in diabetic amyotrophy.

Intravenous immunoglobulin therapy in proximal diabetic neuropathy

A 57-year-old man with type 2 diabetes mellitus for 10 years showed progressive loss of muscle strength in both legs, pain and muscle atrophy in the femoral region and significant weight loss. On admission, he could not stand alone and used a wheelchair. He also complained of severe pain in the lower extremities. He was diagnosed with proximal diabetic neuropathy (PDN) by characteristic clinical and electrophysiological features. Intravenous immunoglobulin therapy (IVIg 0.4 g/kg×5 days) markedly reduced the severe pain and muscle weakness in the legs. Eventually, pain assessed by the Visual Analogue Scale was relieved by 80% and muscle strength was also well recovered, thereby enabling the patient to walk with a cane. The present case suggests that IVIg therapy may be effective for the relief of pain in PDN.

Focal and multifocal diabetic neuropathies

Diabetic neuropathy is the most common neuropathy in industrialized countries, with a remarkable range of clinical manifestations. The vast majority of the patients with clinical diabetic neuropathy have a distal symmetrical form that progress following a fiber-length dependent pattern, with predominant sensory and autonomic manifestations. This pattern of neuropathy is associated with a progressive distal axonopathy. Patients are exposed to trophic changes in the feet, pains and autonomic disturbances. Less often, diabetic patients may develop focal and multifocal neuropathy that includes cranial nerve involvement, limb and truncal neuropathies. This neuropathic pattern tends to occur after 50 years of age, mostly in patients with longstanding diabetes mellitus. The LDDP does not show any trend to improvement and either relentlessly progresses or remain relatively stable over years. Conversely the focal diabetic neuropathies, which are often associated with inflammatory vasculopathy on nerve biopsies, remain self limited, sometimes after a relapsing course.

The spectrum of diabetic neuropathies

Diabetes mellitus is associated with many different neuropathic syndromes, ranging from a mild sensory disturbance as can be seen in a diabetic sensorimotor polyneuropathy, to the debilitating pain and weakness of a diabetic lumbosacral radiculoplexus neuropathy. The etiology of these syndromes has been studied extensively, and may vary among metabolic, compressive, and immunological bases for the different disorders, as well as mechanisms yet to be discovered. Many of these disorders of nerve appear to be separate conditions with different underlying mechanisms, and some are caused directly by diabetes mellitus, whereas others are associated with it but not caused by hyperglycemia. This article discusses a number of the more common disorders of nerve found with diabetes mellitus. It discusses the symmetrical neuropathies, particularly generalized diabetic polyneuropathy, and then the focal or asymmetrical types of diabetes-associated neuropathy.

Inflammatory mediators in diabetic and non-diabetic lumbosacral radiculoplexus neuropathy

Nerve microvasculitis and ischemic injury appear to be the primary and important pathogenic alterations in lumbosacral radiculoplexus neuropathy of patients with (DLRPN) and without (LRPN) diabetes mellitus (DM). Here, we examine the involvement of inflammatory mediators in DLRPN and LRPN. Paraffin sections of sural nerves from 19 patients with DLRPN, 13 patients with LRPN, and 20 disease control patients were immunostained for intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and nuclear factor kappaB (NF-kappaB). The findings were correlated with histopathology. The pathologic and immunohistochemical alterations of DLRPN and LRPN nerves were indistinguishable. The nerves of both types of LRPN had a significantly greater number of ICAM-1 positive vessels than did the controls (P < 0.01). TNF-alpha expression was seen in Schwann cells and some macrophages of DLRPN and LRPN nerves, whereas IL-6 expression was minimal. There was greater NF-kappaB immunoreactivity in vessels and endoneurial cells of DLRPN and LRPN nerves than of the controls (P < 0.001). NF-kappaB expression correlated with the number of empty nerve strands (P < 0.01) and the frequency of axonal degeneration (P < 0.05), whereas TNF-alpha expression correlated inversely with the number of empty nerve strands of teased fibers (P < 0.05). Our findings suggest that up-regulation of inflammatory mediators target different cells at different disease stages and that these mediators may be sequentially involved in an immune-mediated inflammatory process that is shared by both DLRPN and LRPN. Up-regulated inflammatory mediators may be immunotherapeutic targets in these two conditions.

Intravenous immunoglobulin therapy markedly ameliorates muscle weakness and severe pain in proximal diabetic neuropathy

A 57-year-old man with type 2 diabetes mellitus for 10 years showed progressive loss of muscle strength in both legs, pain and muscle atrophy in the femoral region and significant weight loss. On admission, he could not stand alone and used a wheelchair. He also complained of severe pain in the lower extremities. He was diagnosed with proximal diabetic neuropathy (PDN) by characteristic clinical and electrophysiological features. Intravenous immunoglobulin therapy (IVIg 0.4 g/kg x 5 days) markedly reduced the severe pain and muscle weakness in the legs. Eventually, pain assessed by the Visual Analogue Scale was relieved by 80% and muscle strength was also well recovered, thereby enabling the patient to walk with a cane. The present case suggests that IVIg therapy may be effective for the relief of pain in PDN.

Diabetic neuropathy--a review

Diabetic neuropathy is the most common neuropathy in industrialized countries, and it is associated with a wide range of clinical manifestations. The vast majority of patients with clinical diabetic neuropathy have a distal symmetrical form of the disorder that progresses following a fiber-length-dependent pattern, with sensory and autonomic manifestations predominating. This pattern of neuropathy is associated with a progressive distal axonopathy. Patients experience pain, trophic changes in the feet, and autonomic disturbances. Occasionally, patients with diabetes can develop focal and multifocal neuropathies that include cranial nerve involvement and limb and truncal neuropathies. This neuropathic pattern tends to occur after 50 years of age, and mostly in patients with long-standing diabetes mellitus. Length-dependent diabetic polyneuropathy does not show any trend towards improvement, and either relentlessly progresses or remains relatively stable over a number of years. Conversely, the focal diabetic neuropathies, which are often associated with inflammatory vasculopathy on nerve biopsies, remain self-limited, sometimes after a relapsing course.

Vasculitic Neuropathies

BACKGROUND

Systemic vasculitis has been classically categorized as a primary disorder, such as polyarteritis nodosa, Churg-Strauss syndrome, and Wegener granulomatous, or as a secondary process, representing a complication from a connective tissue disorder (eg, rheumatoid vasculitis), infection, medication, or malignancy. Peripheral neuropathy is a well-recognized consequence of systemic vasculitis due to peripheral nerve infarction with Wallerian degeneration. Rarely, neuropathy is the sole manifestation of vasculitis, referred to as nonsystemic vasculitic neuropathy (NSVN). These conditions are defined pathologically by tissue biopsy demonstrating disruption or destruction of the vessel wall with inflammatory cell infiltrates.

REVIEW SUMMARY

The diagnosis of vasculitic neuropathy is straightforward in patients with an established diagnosis of systemic vasculitis and classic features of mononeuritis multiplex. Most patients have clinical features of a subacute, progressive, generalized but asymmetric, painful, sensorimotor polyneuropathy. Laboratory tests often indicate features of systemic inflammation, such as an elevated sedimentation rate or positive anti-neutrophil cytoplasmic antibody, and electrodiagnostic evaluation shows multiple mononeuropathies or a confluent, asymmetric axonal neuropathy. Nerve biopsy is necessary to establish the diagnosis in most cases, particularly in patients with NSVN. This review summarizes the current treatment of vasculitic neuropathy.

CONCLUSION

Long-term immunosuppressive therapy is required in most cases. High-dose prednisone combined with intravenous pulse or oral daily cyclophosphamide is standard initial therapy. In those with NSVN, cyclophosphamide also should be used if prednisone monotherapy is ineffective or the patient relapses with tapering. Other agents, such as azathioprine, methotrexate, intravenous immunoglobulin, mycophenolate mofetil, plasma exchange, and rituximab can be offered to patients who are intolerant or have a contraindication to cyclophosphamide. However, evidence for the benefit of these agents is limited to case reports and small case series.

Therapy for vasculitic neuropathies

The term vasculitis refers to a pathologic condition defined by inflammatory cell infiltration and destruction of blood vessels. Systemic vasculitis is classified as primary (eg, polyarteritis nodosa, Churg-Strauss syndrome) or secondary, the latter associated with connective tissue disorders, infections, medications, and rarely, as a paraneoplastic phenomenon. Neuropathy is a common complication of systemic vasculitis and is related to ischemic nerve fiber damage with axon loss. Peripheral neuropathy may be the sole manifestation of vasculitis, a condition termed nonsystemic vasculitic neuropathy (NSVN). Treatment of vasculitic neuropathy requires long-term immunosuppressive therapies with potential side effects. The diagnosis of vasculitis should be established by tissue (preferably nerve) biopsy. High-dose prednisone is the standard platform therapy for patients with systemic and NSVN; for those with systemic vasculitis, at least 3 to 12 months of treatment with cyclophosphamide (monthly intravenous pulse or daily oral therapy) is also necessary to sustain remission and allow successful prednisone tapering. The use of cyclophosphamide in patients with NSVN is controversial, but recent retrospective data suggest that those treated with prednisone and cyclophosphamide from the outset fare better than those initially treated only with prednisone. If prednisone is administered as monotherapy, cyclophosphamide should be added after several months if there is no improvement or relapse occurs with tapering of prednisone. Intravenous pulse and daily oral cyclophosphamide probably offer similar efficacy, although the risk of complications is greater with oral therapy. Azathioprine can be safely substituted for cyclophosphamide after 3 months without an increased relapse rate. Azathioprine, methotrexate, intravenous immune globulin, mycophenolate mofetil, plasma exchange, and rituximab can be offered to patients who are intolerant or have a contraindication to cyclophosphamide. However, efficacy is unproven for any of these therapies. Interferon-alpha, sometimes combined with plasma exchange, is used to treat vasculitis associated with hepatitis B infection. Some patients also may improve with corticosteroids. The classification of diabetic lumbosacral radiculoplexus neuropathy as a vasculitic disorder remains controversial. However, there is compelling pathological evidence that this condition represents a T-cell-mediated microvasculitis. Some patients treated with intravenous corticosteroids may have greater recovery and improved pain control.

An update on the classification and treatment of vasculitic neuropathy

Vasculitic neuropathy usually presents with painful mononeuropathies or an asymmetric polyneuropathy of acute or subacute onset. The disorder should be classified as being systemic or non-systemic. Systemic vasculitis should be further classified into one of the primary and secondary forms. Although specific treatment regimens vary among neurologists, basic principles can be applied. Corticosteroids and cytotoxic drugs have been the mainstay of treatment for most forms of vasculitic neuropathy. Here we discuss dosing, potential side-effects, and management recommendations of conventional treatments. New treatments showing promise include intravenous immunoglobulin and biological agents and trials of the newest treatments are being reviewed. Future trials should compare commonly used treatment regimens and better establish the efficacy of newer, potentially safer, treatments.

Non-systemic vasculitic neuropathy

PURPOSE OF REVIEW

This article reviews the literature on non-systemic vasculitic neuropathy, with emphasis on recent advances, summarizing the clinical presentation, diagnosis, pathology, treatment, and outcome of this condition, and speculating on its nosological status vis-à-vis the systemic vasculitides.

RECENT FINDINGS

A new cohort of non-systemic vasculitic neuropathy patients was recently reported. Analysis of the clinical characteristics of this cohort demonstrated a higher incidence of painful, asymmetric, overlapping deficits than in previous studies. Extended follow-up revealed a high relapse rate, low risk of systemic spread, high incidence of chronic pain, relatively good neurological outcome, and low mortality rate. Analysis of therapeutic responses showed better outcomes with combination therapy than corticosteroid monotherapy. Another recent report proposed a role for magnetic resonance angiography in the diagnosis and follow-up of non-systemic vasculitic neuropathy. Recent pathological studies implicated proinflammatory cytokines and matrix metalloproteinase-9 in the mediation of vascular and axonal damage in non-systemic vasculitic neuropathy.

SUMMARY

Non-systemic vasculitic neuropathy is one of many localized vasculitides, with involvement restricted to nerves and (possibly) muscles. Inclusion and exclusion criteria differ between reported cohorts. All require a nerve biopsy diagnostic of or suspicious for vasculitis and no extra-neuromuscular involvement. Patients typically present subacutely with a painful, multifocal/asymmetric, distal-predominant neuropathy. In the absence of clinical or laboratory evidence of systemic vasculitis or a condition predisposing to such, prognosis with treatment is good. Pathological data are supportive of a primary T-cell-mediated immunopathogenesis. Some patients classified as having non-systemic vasculitic neuropathy have a systemic vasculitis presenting with neuropathy; in others, the disease is organ-specific.

Diabetic neuropathies

Diabetic neuropathy (DN) is a common complication of diabetes that often is associated with considerable morbidity and mortality. The epidemiology and natural history of DN is clouded with uncertainty because of confusion regarding the definition and measurement of this disorder. The recent resurgence of interest in the vascular hypothesis, oxidative stress, the neurotrophic hypothesis,and the possibility of the role of autoimmunity has opened up new avenues of investigation for therapeutic intervention. The ability to manage successfully the many different manifestations of diabetic neuropathy depends ultimately on success in uncovering the pathogenic processes underlying this disorder.

Advances in understanding and treatment of immune-mediated disorders of the peripheral nervous system

During recent years, novel insights in basic immunology and advances in biotechnology have contributed to an increased understanding of the pathogenetic mechanisms of immune-mediated disorders of the peripheral nervous system. This increased knowledge has an impact on the management of patients with this class of disorders. Current advances are outlined and their implication for therapeutic approaches addressed. As a prototypic immune-mediated neuropathy, special emphasis is placed on the pathogenesis and treatment of the Guillain-Barré syndrome and its variants. Moreover, neuropathies of the chronic inflammatory demyelinating, multifocal motor, and nonsystemic vasculitic types are discussed. This review summarizes recent progress with currently available therapies and--on the basis of present immunopathogenetic concepts--outlines future treatment strategies.

Diabetic thoracic radiculopathy: an unusual cause of post-thoracotomy pain

Persistent pain is common following thoracotomy. A 64-year-old retired electrician with Type 2 diabetes presented with chest wall and abdominal pain 3 months following video-assisted thoracoscopic surgery (VATS). Postoperatively the patient had suffered pain despite a functioning thoracic epidural catheter. Following investigation, his persistent pain was due to diabetic thoracic radiculopathy (DTR). The disorder is characterized by pain, sensory loss, abdominal and thoracic muscle weakness in patients with diabetes. As in this patient, the pain and sensory loss usually resolve within one year after onset. The disorder may be distinguished from intercostal neuralgia based upon clinical and electromyographic features.