Epidemiology of chronic inflammatory neuropathies in southeast England

Proteomics analysis of immune response-related proteins in Guillain-Barré Syndrome (GBS) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

The objective is to characterize differentially expressed proteins (DEPs) in Guillain-Barré Syndrome (GBS) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) through high-throughput analysis. Sera from 11 healthy controls (HCs), 21 GBS and 19 CIDP patients were subjected to Olink Proteomics Analysis. In the comparison between CIDP and GBS groups, up-regulation of ITM2A and down-regulation of NTF4 were observed. Comparing GBS with HCs revealed 18 up-regulated and 4 down-regulated proteins. Comparing CIDP with the HCs identified 15 up-regulated and 4 down-regulated proteins. Additionally, the correlation between clinical characteristics and DEPs were uncovered. In conclusion, the DEPs have significant potential to advance our understanding of the pathogenesis in these debilitating neurological disorders.

Immunoglobulin use in neurology: a practical approach

Human immunoglobulin, delivered either intravenously (IVIg) or subcutaneously, is used to treat a range of immune-mediated neurological disorders. It has a role in acute or subacute inflammatory disease control and as a maintenance therapy in chronic disease management. This review considers mechanisms of IVIg action and the evidence for IVIg in neurological conditions. We use Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) as frameworks to demonstrate an approach to IVIg use in acute and chronic dysimmune neurological conditions across two different healthcare systems: the UK and Australia. We highlight the benefits and limitations of IVIg and focus on practical considerations such as informed consent, managing risks and adverse effects, optimal dosing and monitoring response. We use these basic clinical practice principles to discuss the judicious use of an expensive and scarce blood product with international relevance.

A pathologically expanded, clonal lineage of IL-21-producing CD4+ T cells drives inflammatory neuropathy

Inflammatory neuropathies, which include chronic inflammatory demyelinating polyneuropathy (CIDP) and Guillain Barré syndrome (GBS), result from autoimmune destruction of the PNS and are characterized by progressive weakness and sensory loss. CD4+ T cells play a key role in the autoimmune destruction of the PNS. Yet, key properties of pathogenic CD4+ T cells remain incompletely understood. Here, we used paired single-cell RNA-Seq (scRNA-Seq) and single-cell T cell receptor-sequencing (scTCR-Seq) of peripheral nerves from an inflammatory neuropathy mouse model to identify IL-21-expressing CD4+ T cells that were clonally expanded and multifunctional. These IL-21-expressing CD4+ T cells consisted of 2 transcriptionally distinct expanded cell populations, which expressed genes associated with T follicular helper (Tfh) and T peripheral helper (Tph) cell subsets. Remarkably, TCR clonotypes were shared between these 2 IL-21-expressing cell populations, suggesting a common lineage differentiation pathway. Finally, we demonstrated that IL-21 receptor-KO (IL-21R-KO) mice were protected from neuropathy development and had decreased immune infiltration into peripheral nerves. IL-21 signaling upregulated CXCR6, a chemokine receptor that promotes CD4+ T cell localization in peripheral nerves. Together, these findings point to IL-21 signaling, Tfh/Tph differentiation, and CXCR6-mediated cellular localization as potential therapeutic targets in inflammatory neuropathies.

Anti-MAG neuropathy: historical aspects, clinical-pathological correlations, and considerations for future therapeutical trials

BACKGROUND

 Patients with anti-MAG neuropathy present with distal demyelinating polyneuropathy, IgM monoclonal gammopathy, and elevated titers of anti-MAG antibodies.

OBJECTIVE

 This paper reviews what is known about the clinical presentation, course, pathophysiology, and treatment of anti-MAG neuropathy, with considerations for the design of therapeutic trials.

METHODS

 A literature review of the medical and scientific literature related to anti-MAG neuropathy, and the design of therapeutic clinical trials in peripheral neuropathy.

RESULTS

 Anti-MAG neuropathy can remain indolent for many years but then enter a progressive phase. Highly elevated antibody titers are diagnostic, but intermediate titers can also occur in chronic inflammatory demyelinating polyneuropathy (CIDP). The peripheral nerves can become inexcitable, thereby masking the demyelinating abnormalities. There is good evidence that the anti-MAG antibodies cause neuropathy. Reduction of the autoantibody concentration by agents that target B-cells was reported to result in clinical improvement in case series and uncontrolled trials, but not in controlled clinical trials, probably due to inadequate trial design.

CONCLUSION

 We propose that therapeutic trials for anti-MAG neuropathy include patients with the typical presentation, some degree of weakness, highly elevated anti-MAG antibody titers, and at least one nerve exhibiting demyelinating range abnormalities. Treatment with one or a combination of anti-B-cell agents would aim at reducing the autoantibody concentration by at least 60%. A trial duration of 2 years may be required to show efficacy. The neuropathy impairment score of the lower extremities (NIS-LL) plus the Lower Limb Function (LLF) score would be a suitable primary outcome measure.

[Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)]

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common chronic autoimmune disease of the peripheral nervous system. It is often difficult to diagnose, but severaly therapeutic options are nowadays available to reduce neurological deficits and to improve the disease course. This article exemplifies the management of CIDP by a typical case study.

Prevalence, Clinical Profiles, and Prognosis of CIDP in Japanese Nationwide Survey: Analyses of 1,257 Diagnosis-Confirmed Patients

BACKGROUND AND OBJECTIVES

To investigate the current epidemiology, clinical profile, and treatment of chronic inflammatory demyelinating polyneuropathy (CIDP) using a nationwide survey in Japan.

METHODS

We conducted a nationwide survey using an epidemiologic method established in 2021. Questionnaire sheets were sent to the hospital departments of neurology and pediatric neurology throughout Japan. A primary questionnaire was used to determine the number of patients and their prevalence, and a second questionnaire was used to collect detailed clinical information.

RESULTS

The primary survey showed that the estimated number of patients with CIDP was 4,180, with a prevalence of 3.3 per 100,000 persons. In the secondary survey, detailed clinical data were available for 1,257 patients. The male-to-female ratio was 1.5:1, and the median age at onset was 52 years. Typical CIDP was the most frequent subtype (52%), followed by distal (17%) and multifocal/focal CIDP (17%). Initial treatments included immunoglobulin therapy (72%), corticosteroids (15%), and others (13%). Among patients with CIDP, 78% had a progressive/relapsing course, 14% did not respond to first-line treatments, and 18% could not walk independently at the last visit. Among the subtypes, typical CIDP had the most severe disability before treatment (44% of patients could not walk independently). However, they showed a more favorable response to treatment than those with distal or multifocal CIDP. In the subgroup analyses, logistic regression analyses showed that younger age at onset, no muscle atrophy, and abnormal median-normal sural sensory nerve responses were associated with a higher probability of independent walking.

DISCUSSION

Our study represents the largest cohort study on CIDP to demonstrate the current epidemiologic and clinical status of CIDP in Japan. Clinical subtypes seem to be associated with different treatment responses and outcomes; therefore, an appropriate treatment strategy according to the pathophysiology of each subtype is required to improve the prognosis of CIDP.

Lenalidomide in the treatment of anti-myelin-associated glycoprotein neuropathy: A phase 1 study to identify the maximum tolerated dose

BACKGROUND

Anti-myelin-associated glycoprotein (MAG) neuropathy is a debilitating demyelinating polyneuropathy with no approved therapies. Our primary objective was to ascertain lenalidomide safety and maximum tolerated dose (MTD) in anti-MAG neuropathy.

METHODS

This phase 1b, open-label, single-arm, dose-finding trial was conducted from 2019 through 2022. The original design included a dose-escalation/extension phase followed by a dose-expansion phase. Three doses of lenalidomide were evaluated: 10, 15, and 25 mg. The main outcome was the MTD.

RESULTS

Eleven patients enrolled (10 men), with a mean age of 67.6 years (SD = 6.18, range 58-77 years) and mean disease duration of 8.5 years (SD = 10.9, range 1-40 years). The study terminated early due to higher-than-expected non-dose-limiting toxicity venous thromboembolism (VTE) events. The calculated MTD was 25 mg (posterior mean of toxicity probability was 0.01 with a 95% credible interval of 0.00, 0.06), but a recommended phase 2 dose of 15 mg was advised. For secondary exploratory outcomes, only EQ-5D (-0.95, 95% CI -1.81 to -0.09) and total IgM (-162 mg/dL, 95% CI -298 to -26) showed signs of improvement by month 12.

CONCLUSIONS

Lenalidomide was associated with higher-than-expected VTE events in anti-MAG neuropathy patients, despite a calculated MTD of 25 mg. A recommended phase 2 dose of 15 mg was advised. Lenalidomide did not improve disability or impairment at 12 months, although this study was not powered for efficacy. The risks of long term lenalidomide may outweigh benefit for patients with anti-MAG neuropathy. Any future efficacy study should address VTE risk, as current myeloma guidelines appear inadequate.

TRIAL REGISTRATION

Lenalidomide in Anti-MAG Neuropathy: Phase 1b Study, ClinicalTrials.gov Identifier: NCT03701711, https://clinicaltrials.gov/ct2/show/NCT03701711. First submitted October 10, 2018. First patient enrolled in January 2019.

Comparative analysis of albumin quotient and total CSF protein in immune-mediated neuropathies: a multicenter study on diagnostic implications

Introduction

Blood-cerebrospinal fluid (CSF) barrier dysfunction is pivotal for diagnosing immune-mediated neuropathies, especially in spinal nerve root inflammation. Typically, either total CSF protein or the CSF to serum albumin ratio (QAlb) is measured. Total CSF protein measurements have limitations, notably its fixed reference value regardless of age, in contrast to the age-dependent reference for QAlb. Our goal was to evaluate both markers in patients with immune-mediated neuropathies.

Methods

In our multicenter research, we collected retrospective CSF data from patients suffering from immune-mediated neuropathies across four German research centers. These parameters were analyzed in relation to their clinical characteristics.

Results

Out of 419 samples, 36 (8.6%) displayed a notable variation between total CSF protein and QAlb values. A detailed analysis revealed that patients displaying elevated QAlb but normal total CSF protein levels were significantly younger at disease onset (p = 0.01), at the time of diagnosis (p = 0.005), and when undergoing lumbar puncture (p = 0.001) compared to patients with elevated CSF protein and normal QAlb levels. These effects were especially evident for the subgroup of samples derived by female patients.

Discussion

Our work confirms the crucial role of QAlb in diagnosing immune-mediated neuropathies and particularly its efficacy as a marker for evaluating the blood-CSF barrier in patients with an earlier disease onset. Considering the significance of the albumin quotient, its assessment is especially advisable in younger patients of female sex to avoid missing a potential barrier dysfunction that might be falsely negative when using total protein.

A pathologically expanded, clonal lineage of IL-21 producing CD4+ T cells drives Inflammatory neuropathy

Inflammatory neuropathies, which include CIDP (chronic inflammatory demyelinating polyneuropathy) and GBS (Guillain Barre Syndrome), result from autoimmune destruction of the peripheral nervous system (PNS) and are characterized by progressive weakness and sensory loss. CD4+ T cells play a key role in the autoimmune destruction of the PNS. Yet, key properties of pathogenic CD4+ T cells remain incompletely understood. Here, we use paired scRNAseq and scTCRseq of peripheral nerves from an inflammatory neuropathy mouse model to identify IL-21 expressing CD4+ T cells that are clonally expanded and multifunctional. These IL-21-expressing CD4+ T cells are comprised of two transcriptionally distinct expanded populations, which express genes associated with Tfh and Tph subsets. Remarkably, TCR clonotypes are shared between these two IL-21-expressing populations, suggesting a common lineage differentiation pathway. Finally, we demonstrate that IL-21 signaling is required for neuropathy development and pathogenic T cell infiltration into peripheral nerves. IL-21 signaling upregulates CXCR6, a chemokine receptor that promotes CD4+ T cell localization in peripheral nerves. Together, these findings point to IL-21 signaling, Tfh/Tph differentiation, and CXCR6-mediated cellular localization as potential therapeutic targets in inflammatory neuropathies.

[Modern aspects of diagnosis and treatment of chronic inflammatory demyelinating polyneuropathy in children]

OBJECTIVE

Analysis of demographic, clinical, laboratory, electrophysiological and neuroimaging data and pathogenetic therapy of pediatric patients with chronic inflammatory demyelinating polyneuropathy (CIDP).

MATERIAL AND METHODS

Patients (n=30) were observed in a separate structural unit of the Russian Children's Clinical Hospital of the Russian National Research Medical University named after. N.I. Pirogova Ministry of Health of the Russian Federation in the period from 2006 to 2023. The examination was carried out in accordance with the recommendations of the Joint Task Force of the European Federation of Neurological Societies and the Peripheral Nerve Society on the Management of CIDP (2021). All patients received immunotherapy, including intravenous immunoglobulin (IVIG) (n=1), IVIG and glucocorticosteroids (GCS) (n=17, 56.7%), IVIG+GCS+plasmapheresis (n=12, 40.0%). Alternative therapy included cyclophosphamide (n=1), cyclophosphamide followed by mycophenolate mofetil (n=1), rituximab (n=2, 6.6%), azathioprine (n=3), mycophenolate mofetil (n=2, 6.6%).

RESULTS

In all patients, there was a significant difference between scores on the MRCss and INCAT functional scales before and after treatment. At the moment, 11/30 (36.6%) patients are in clinical remission and are not receiving pathogenetic therapy. The median duration of remission is 48 months (30-84). The longest remission (84 months) was observed in a patient with the onset of CIDP at the age of 1 year 7 months.

CONCLUSION

Early diagnosis of CIDP is important, since the disease is potentially curable; early administration of pathogenetic therapy provides a long-term favorable prognosis.

Anti-myelin-associated glycoprotein neuropathy: Where do we stand?

Myelin-associated glycoprotein (MAG) is a transmembrane glycoprotein concentrated in periaxonal Schwann cell and oligodendroglial membranes of myelin sheaths that serves as an antigen for immunoglobulin M (IgM) monoclonal antibodies. Individuals who harbor anti-MAG antibodies classically develop a progressive autoimmune peripheral neuropathy characterized clinically by ataxia, distal sensory loss, and gait instability, and electrophysiologically by distally accentuated conduction velocity slowing. Although off-label immunotherapy is common, there are currently no proven effective disease-modifying therapeutics, and most patients experience slow accumulation of disability over years and decades. The typically slowly progressive nature of this neuropathy presents unique challenges when trying to find effective anti-MAG therapeutic agents. Drug development has also been hampered by the lack of validated outcome measures that can detect clinically meaningful changes in a reasonable amount of time as well as by the lack of disease activity biomarkers. In this invited review, we provide an update on the state of clinicometric outcome measures and disease activity biomarkers in anti-MAG neuropathy. We highlight the insensitivity of widely used existing clinicometric outcome measures such as the Inflammatory Neuropathy Cause and Treatment (INCAT) disability score as well as the INCAT sensory subscore in anti-MAG neuropathy, referencing the two previous negative randomized controlled clinical trials evaluating rituximab. We then discuss newly emerging candidate therapeutic agents, including tyrosine kinase inhibitors and enhanced B-cell-depleting agents, among others. We conclude with a practical approach to the evaluation and management of anti-MAG neuropathy patients.

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.

Sex differences in Guillain Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy and experimental autoimmune neuritis

Guillain Barré syndrome (GBS) and its variants, and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP and its variants, are regarded as immune mediated neuropathies. Unlike in many autoimmune disorders, GBS and CIDP are more common in males than females. Sex is not a clear predictor of outcome. Experimental autoimmune neuritis (EAN) is an animal model of these diseases, but there are no studies of the effects of sex in EAN. The pathogenesis of GBS and CIDP involves immune response to non-protein antigens, antigen presentation through non-conventional T cells and, in CIDP with nodopathy, IgG4 antibody responses to antigens. There are some reported sex differences in some of these elements of the immune system and we speculate that these sex differences could contribute to the male predominance of these diseases, and suggest that sex differences in peripheral nerves is a topic worthy of further study.

Prevalence of chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy in two regions of Australia

INTRODUCTION/AIMS

Immune-mediated neuropathies such as chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN) produce significant disability and often require maintenance treatment. There is a paucity of epidemiological data on these conditions in Australia.

METHODS

We undertook a prevalence study of CIDP and MMN in North Queensland and Tasmania, coinciding with a national census. Diagnoses were classified against the diagnostic criteria of the European Federation of Neurological Societies/Peripheral Nerve Society. Case ascertainment was undertaken via multiple methods, including survey of local neurologists across public and private clinics, search of neurophysiology, neurology and hospital databases, search of admitted hospital database collections using ICD codes and through immunoglobulin therapy prescription lists.

RESULTS

The crude prevalence of CIDP was 5.00 per 100,000 (95% confidence interval [CI] 3.79-6.62) and the crude prevalence of MMN was 1.33 per 100,000 (95% CI 0.78-2.27). Prevalence was also investigated using National Blood Authority numbers of cases prescribed immunoglobulin therapy, indicating a CIDP prevalence of 5.72 per 100,000 (95% CI 4.41-7.43) and MMN prevalence of 1.94 per 100,000 (95% CI 1.24-3.03). There was no significant difference between these numbers and those calculated through access of patient records locally. There was no significant difference in prevalence between Tasmania and North Queensland for any category.

DISCUSSION

This study updates the prevalence of CIDP and MMN in Australia. Understanding the distribution of CIDP and MMN patients and their need for treatment is essential for future resource planning and to enable monitoring and coordination of therapies such as immunoglobulin.

Epidemiology of chronic inflammatory demyelinating polyradiculoneuropathy in The Netherlands

BACKGROUND AND AIMS

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare but disabling disorder that often requires long-term immunomodulatory treatment. Background incidence rates and prevalence and risk factors for developing CIDP are still poorly defined. In the current study, we used a longitudinal population-based cohort study in The Netherlands to assess these rates and demographic factors and comorbidity associated with CIDP.

METHODS

We determined the incidence rate and prevalence of CIDP between 2008-2017 and the occurrence of potential risk factors in a retrospective Dutch cohort study using the Integrated Primary Care Information (IPCI) database. Cases were defined as CIDP if the diagnosis of CIDP was described in the electronic medical file.

RESULTS

In a source population of 928,030 persons with a contributing follow-up of 3,525,686 person-years, we identified 65 patients diagnosed with CIDP. The overall incidence rate was 0.68 per 100,000 person-years (95% CI 0.45-0.99). The overall prevalence was 7.00 per 100,000 individuals (95% CI 5.41-8.93). The overall incidence rate was higher in men compared to woman (IRR 3.00, 95% CI 1.27-7.11), and higher in elderly of 50 years or older compared to people <50 years of age (IRR 17 95% CI 4-73). Twenty percent of CIDP cases had DM and 9% a co-existing other autoimmune disease.

INTERPRETATION

These background rates are important to monitor changes in the frequency of CIDP following infectious disease outbreaks identify potential risk factors, and to estimate the social and economic burden of CIDP.

The Role of the Complement System in Chronic Inflammatory Demyelinating Polyneuropathy: Implications for Complement-Targeted Therapies

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common, heterogeneous, immune-mediated neuropathy, characterized by predominant demyelination of motor and sensory nerves. CIDP follows a relapsing-remitting or a progressive course and causes substantial disability. The pathogenesis of CIDP involves a complex interplay of multiple aberrant immune responses, creating a pro-inflammatory environment, subsequently inflicting damage on the myelin sheath. Though the exact triggers are unclear, diverse immune mechanisms encompassing cellular and humoral pathways are implicated. The complement system appears to play a role in promoting macrophage-mediated demyelination. Complement deposition in sural nerve biopsies, as well as signs of increased complement activation in serum and CSF of patients with CIDP, suggest complement involvement in CIDP pathogenesis. Here, we present a comprehensive overview of the preclinical and clinical evidence supporting the potential role of the complement system in CIDP. This understanding furnishes a strong rationale for targeting the complement system to develop new therapies that could serve the unmet needs of patients affected by CIDP, particularly in those refractory to standard therapies.

CIDP: Current Treatments and Identification of Targets for Future Specific Therapeutic Intervention

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired immune-mediated inflammatory disorder of the peripheral nervous system. This clinically heterogeneous neurological disorder is closely related to Guillain–Barré syndrome and is considered the chronic counterpart of that acute disease. Currently available treatments are mostly empirical; they include corticosteroids, intravenous immunoglobulins, plasma exchange and chronic immunosuppressive agents, either alone or in combination. Recent advances in the understanding of the underlying pathogenic mechanisms in CIDP have brought a number of novel ways of possible intervention for use in CIDP. This review summarizes selected pre-clinical and clinical findings, highlights the importance of using adapted animal models to evaluate the efficacy of novel treatments, and proposes the outlines of future directions to ameliorate the conditions of patients with CIDP.

Decrease in Serum Anti-MAG Autoantibodies Is Associated With Therapy Response in Patients With Anti-MAG Neuropathy: Retrospective Study

Background and Objectives

The objective of the retrospective analysis was to test the hypothesis that changes in serum anti-myelin-associated glycoprotein (MAG) autoantibodies are associated with clinical response to immunotherapy in patients with anti-MAG neuropathy.

Methods

As of January 29, 2020, we used anti-myelin-associated glycoprotein-related search strings in the Medline database to identify studies that provided information on anti-MAG immunoglobulin M (IgM) autoantibodies and clinical outcomes during immunotherapies. The relative change in anti-MAG IgM titers, paraprotein levels, or total IgM was determined before, during, or posttreatment, and the patients were assigned to “responder,” “nonresponder,”’ or “acute deteriorating” category depending on their clinical response to treatment. The studies were qualified as “supportive” or “not supportive” depending on the percentage of patients exhibiting an association between relative change of anti-MAG antibody titers or levels and change in clinical outcomes.

Results

Fifty studies with 410 patients with anti-MAG neuropathy were included in the analysis. Forty studies with 303 patients supported the hypothesis that a “responder” patient had a relative reduction of anti-MAG antibody titers or levels that is associated with clinical improvements and “nonresponder” patients exhibited no significant change in anti-MAG IgM antibodies. Six studies with 93 patients partly supported, and 4 studies with 26 patients did not support the hypothesis.

Discussion

The retrospective analysis confirmed the hypothesis that a relative reduction in serum anti-MAG IgM antibodies is associated with a clinical response to immunotherapies; a sustained reduction of at least 50% compared with pretreatment titers or levels could be a valuable indicator for therapeutic response.

Chronic inflammatory demyelinating polyneuropathy in Spain: a retrospective analysis of hospital incidence and medical costs

BACKGROUND

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare disorder that usually involves long-term impairment. Despite the chronic health-care needs that are often associated, research evaluating the economic burden of this disorder is still scarce. This study aimed to assess the characteristics of patients admitted with CIDP in Spanish hospitals and to determine the associated medical costs.

METHODS

A retrospective multicenter study was designed analyzing records of hospital and ambulatory visits of patients with CIDP in Spanish hospitals between 2004 and 2018. Medical costs registered in hospital facilities were evaluated.

RESULTS

Admission files corresponding to 2805 patients diagnosed with CIDP were extracted from the database: 64.7% of patients were males, and median age was 60 years. Patients presented comorbidities that included essential hypertension, hypercholesterolemia, and diabetes mellitus. The raw number of admissions for CIDP increased significantly over the study period, similarly to mean admission costs for all age groups. Consequently, total hospital medical costs associated with CIDP increased over the study period. The mean medical cost per admission was €3953.

CONCLUSIONS

The increasing number of hospital cases of CIDP is associated with rising medical costs. Further research will be required to fully evaluate the medical and societal burdens of this disorder.

Dose-dependent immunomodulatory effects of bortezomib in experimental autoimmune neuritis

Proteasome inhibition with bortezomib has been reported to exert an immunomodulatory action in chronic autoimmune neuropathies. However, bortezomib used for the treatment of multiple myeloma induces a painful toxic polyneuropathy at a higher concentration. Therefore, we addressed this controversial effect and evaluated the neurotoxic and immunomodulatory mode of action of bortezomib in experimental autoimmune neuritis. Bortezomib-induced neuropathy was investigated in Lewis rats using the von Frey hair test, electrophysiological, qPCR and histological analyses of the sciatic nerve as well as dorsal root ganglia outgrowth studies. The immunomodulatory potential of bortezomib was characterized in Lewis rats after experimental autoimmune neuritis induction with P2_53-78 peptide. Clinical, electrophysiological, histological evaluation, von Frey hair test, flow cytometric and mRNA analyses were used to unravel the underlying mechanisms. We defined the toxic concentration of 0.2 mg/kg bortezomib applied intraperitoneally at Days 0, 4, 8 and 12. This dosage induces a painful toxic neuropathy but preserves axonal regeneration in vitro. Bortezomib at a concentration of 0.05 mg/kg significantly ameliorated experimental autoimmune neuritis symptoms, improved experimental autoimmune neuritis-induced hyperalgesia and nerve conduction studies, and reduced immune cell infiltration. Furthermore, proteasome inhibition induced a transcriptional downregulation of Nfkb in the sciatic nerve, while its inhibitor Ikba (also known as Nfkbia) was upregulated. Histological analyses of bone marrow tissue revealed a compensatory increase of CD138⁺ plasma cells. Our data suggest that low dose bortezomib (0.05 mg/kg intraperitoneally) has an immunomodulatory effect in the context of experimental autoimmune neuritis through proteasome inhibition and downregulation of nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NFKB). Higher bortezomib concentrations (0.2 mg/kg intraperitoneally) induce sensory neuropathy; however, the regeneration potential remains unaffected. Our data empathizes that bortezomib may serve as an attractive treatment option for inflammatory neuropathies in lower concentrations.

The Role of Plasma Exchange in the Treatment of Refractory Autoimmune Neurological Diseases: a Narrative Review

Autoimmune neurological disorders are commonly treated with immunosuppressive therapy. In patients with refractory conditions, standard immunosuppression is often insufficient for complete recovery or to prevent relapses. These patients rely on other treatments to manage their disease. While treatment of refractory cases differs between diseases, intravenous immunoglobulin, plasma exchange (PLEX), and immune-modulating treatments are commonly used. In this review, we focus on five autoimmune neurological disorders that were the themes of the 2018 Midlands Neurological Society meeting on PLEX in refractory neurology: Autoimmune Encephalitis (AE), Multiple Sclerosis (MS), Neuromyelitis Optica Spectrum disorders (NMOSD), Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) and Myasthenia Gravis (MG). The diagnosis of inflammatory neuropathies is often challenging, and while PLEX can be very effective in refractory autoimmune diseases, its ineffectiveness can be confounded by misdiagnosis. One example is POEMS syndrome (characterized by Polyneuropathy Organomegaly, Endocrinopathy, Myeloma protein, Skin changes), which is often wrongly diagnosed as CIDP; and while CIDP responds well to PLEX, POEMS does not. Accurate diagnosis is therefore essential. Success rates can also differ within 'one' disease: e.g. response rates to PLEX are considerably higher in refractory relapsing remitting MS compared to primary or secondary progressive MS. When sufficient efforts are made to correctly pinpoint the diagnosis along with the type and subtype of refractory autoimmune disease, PLEX and other immunotherapies can play a valuable role in the patient management.

Atypical chronic inflammatory demyelinating polyradiculoneuropathy: recent advances on classification, diagnosis, and pathogenesis

PURPOSE OF REVIEW

In recent years, there has been an intense debate in literature regarding the definition of the individual variants of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), their possible pathogenetic mechanisms, and impact in the diagnosis of CIDP.

RECENT FINDINGS

The 2021 European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) guidelines revised the definition of the individual CIDP variants and implemented their diagnostic criteria. Diagnosis of atypical CIDP is challenging and misdiagnosis is frequent, leading to diagnostic delay and consequent greater accumulation of disability and treatment dependency. Recent studies suggest that patients with typical CIDP have an antibody-mediated mechanism of neuropathy whereas in those with Lewis--Sumner syndrome (LSS) neuropathy is preferentially mediated by macrophages and T cells.

SUMMARY

Although the validity of the 2021 EFNS/PNS diagnostic criteria for atypical CIDP is unknown, they will hopefully lead to greater uniformity in the selection of patients to be enrolled in future studies and to a greater diagnostic accuracy. New data are emerging on the possible pathological mechanisms of individual variants and this could result in the discovery of specific diagnostic biomarkers and new therapies.

Retrospective analysis of response to rituximab in chronic inflammatory demyelinating polyneuropathy refractory to first-line therapy

Few case reports/series describe the efficacy of rituximab in refractory chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), which is preferred in the presence of anti-nodal/paranodal antibodies. We aimed at evaluating the clinical response to rituximab in a subset of patients with refractory CIDP for whom the anti-nodal/paranodal antibodies status was unknown, as not available in Iran. We retrospectively analyzed the response to rituximab in 14 Iranian patients with refractory CIDP (3 children, 11 adults), in whom the anti-nodal/paranodal antibodies status was unknown. The subjects were evaluated with the Medical Research Council (MRC) sum score (MRCSS), Inflammatory Neuropathy Cause and Treatment (INCAT) disability scores, and electrophysiology, before and after treatment. Mean age was 34.4 ± 20.7 years, disease duration pre-rituximab treatment was 27.8 ± 18.8 (range: 6-60) months, and mean follow-up duration was 18.5 ± 11.0 (range: 4-36) months. Considering the INCAT sum score, one worsened during post-rituximab treatment, and three patients did not change. Considering MRCSS, notably, four patients achieved normalization of their MRCSS. Regarding the corticosteroid dose, two patients could discontinue prednisolone. As rated by a pre-defined scoring system, nerve conduction parameters improved significantly post-rituximab in the treated cohort (P = .006). All patients tolerated rituximab infusions without adverse effects. Rituximab may be effective in refractory CIDP, even though worsening may occur in some patients. Anti-nodal/paranodal antibodies assay, when available, and other criteria may help drive therapeutic decision-making on rituximab as second-line treatment.

Chronic inflammatory demyelinating polyneuropathy and pregnancy: systematic review

Pregnancy largely affects disease activity and clinical course in women with immune-mediated neurological disorders. Chronic inflammatory demyelinating polyneuropathy (CIDP) is rare but the most common chronic immune-mediated neuropathy; however, the effects of pregnancy on CIDP have never been investigated except case reports or series. We here provide a systematic review of the literature from 1 January 1969 to 30 June 2020 that revealed 24 women with CIDP, who had onset or relapse during pregnancy. Of these, 17 (71%) developed CIDP during the first pregnancy, and 8 (47%) had a relapse during subsequent pregnancies. Of the 17 patients, in whom the CIDP subtypes were determined, all of them had typical CIDP. First-line treatments for CIDP, such as corticosteroids, immunoglobulin and plasma exchange were efficacious and safe. We suggest that pregnancy can trigger typical CIDP in some women, and women with CIDP have a higher risk of relapse during pregnancy. The onset or relapse of CIDP during pregnancy is a rare but challenging constellation for physicians.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy During the COVID-19 Pandemic: Telemedicine Limitations and Strategies for Improvement

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is a relapsing-remitting or progressive inflammatory neuropathy, which can present in a multitude of phenotypes. It can be a challenging condition to diagnose and requires thorough clinical evaluation and electrodiagnostic testing. With the outbreak of coronavirus disease in 2019 (COVID-19), large portions of the medical field converted to telemedicine to facilitate patient visits. We report a case of a 50-year-old female who was seen via video visit during the COVID-19 pandemic who was later diagnosed with CIDP and treated with intravenous immunoglobulins with improvement in clinical examination and electrodiagnostic testing. This case highlights the limitations of performing the neuromuscular examination via telemedicine.

Treatment response to cyclophosphamide, rituximab, and bortezomib in chronic immune-mediated sensorimotor neuropathies: a retrospective cohort study

Background:

Up to 20% of patients with chronic immune-mediated sensorimotor neuropathies (CIN) do not respond adequately to first-line therapies. However, studies on further treatment are scarce.

Methods:

We analyzed retrospectively 200 CIN patients regarding disease characteristics and response to therapy with cyclophosphamide (CYP), rituximab (RTX), and bortezomib (BTZ). Treatment response was defined as improvement or stabilization of inflammatory neuropathy cause and treatment overall disability score (INCAT-ODSS).

Results:

A total of 48 of 181 patients (26.5%) received therapy with CYP, RTX, or BTZ. The most frequently and first used therapy was CYP (69%). More than 40% of patients needed a second or third treatment. Overall, 71 treatments were applied in 48 patients. The combination of up to all three treatments enhanced the response-rate to 90%. Treatment within 24 months after initial diagnosis resulted in significantly higher response rate than late treatment (79% versus 50 %, p = 0.04, χ²-test, n = 46) and in lower disability in long-term follow up (INCAT-ODSS 3.8 versus 5.8, p = 0.02, t-test, n = 48). Patients with Lewis-Sumner syndrome (n = 9) and autoantibody mediated neuropathies (n = 13) had excellent response rates after treatment with RTX (90–100%). In contrast, typical chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) showed a response rate of 64% in CYP, 64% in RTX, and 75% in BTZ.

Conclusion:

Treatment with CYP, RTX, or BTZ was effective in this cohort of CIN refractory to first-line treatment. Our data increase evidence for an early use of these therapies. High efficacy of RTX in Lewis-Sumner syndrome in contrast to typical CIDP suggests a distinct pathophysiology.

Semi-Automatic MRI Muscle Volumetry to Diagnose and Monitor Hereditary and Acquired Polyneuropathies

With emerging treatment approaches, it is crucial to correctly diagnose and monitor hereditary and acquired polyneuropathies. This study aimed to assess the validity and accuracy of magnet resonance imaging (MRI)-based muscle volumetry.Using semi-automatic segmentations of upper- and lower leg muscles based on whole-body MRI and axial T1-weighted turbo spin-echo sequences, we compared and correlated muscle volumes, and clinical and neurophysiological parameters in demyelinating Charcot-Marie-Tooth disease (CMT) (n = 13), chronic inflammatory demyelinating polyneuropathy (CIDP) (n = 27), and other neuropathy (n = 17) patients.The muscle volumes of lower legs correlated with foot dorsiflexion strength (p < 0.0001), CMT Neuropathy Score 2 (p < 0.0001), early gait disorders (p = 0.0486), and in CIDP patients with tibial nerve conduction velocities (p = 0.0092). Lower (p = 0.0218) and upper (p = 0.0342) leg muscles were significantly larger in CIDP compared to CMT patients. At one-year follow-up (n = 15), leg muscle volumes showed no significant decrease.MRI muscle volumetry is a promising method to differentiate and characterize neuropathies in clinical practice.

Juvenile Chronic Inflammatory Demyelinating Polyneuropathy Epidemiology in Sardinia, Insular Italy

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare and disabling immunomediated radiculoneuropathy. Its worldwide epidemiology is heterogeneous and, in adults, CIDP prevalence varies from 0.6 to 9 cases per 100,000 population. Juvenile CIDP (jCIDP) is even rarer, with age-specific prevalence rates varying from 0.23 to 1.26 owing to different diagnostic criteria (American Academy of Neurology [AAN] and European Federation of Neurological Societies/Peripheral Nerve Society [EFNS/PNS]), different age grouping or, genuine differences.

OBJECTIVES

We assessed jCIDP incidence and prevalence in Sardinia, an area at very-high risk for autoimmune diseases, using comparable methods.

DESIGN

The study area was the northern Sardinia, insular Italy, with 491,571 inhabitants and a pediatric population (0-18 years) of 79,086 individuals.

RESULTS

On prevalence day (December 31, 2019) the total crude, age-specific prevalence rate were 6.32 per 100,000 according with AAN criteria, 7.58 per 100,000 population with European Neuromuscular Center (ENMC) criteria, and 8.85 per 100,000 population with both 2006 and 2010 EFNS/PNS criteria. Crude mean incidence rate were 0.42 per 100,000 per year with AAN criteria, 0.50 per 100,000 per year with ENMC criteria, and 0.59 per 100,000 per year using 2006 and 2010 EFNS/PNS criteria. Of the eight patients, six had typical CIDP, one had multifocal-acquired demyelinating sensory and motor neuropathy (MADSAM), and one chronic immune sensory polyradiculopathy (CISP). Patient's disability was generally mild. Clinical course was progressive, monophasic, or relapsing.

CONCLUSION

jCIDP prevalence and incidence rates in Sardinia were criteria-dependent, the lowest obtained when using AAN criteria, the highest using the EFNS/PNS. Nonetheless, even with the exclusion of the "possible" category, by using comparable methodology, prevalence rates in Sardinia are considerably higher than the range reported in all previous jCIDP studies.

Implication of Contactins in Demyelinating Pathologies

Demyelinating pathologies comprise of a variety of conditions where either central or peripheral myelin is attacked, resulting in white matter lesions and neurodegeneration. Myelinated axons are organized into molecularly distinct domains, and this segregation is crucial for their proper function. These defined domains are differentially affected at the different stages of demyelination as well as at the lesion and perilesion sites. Among the main players in myelinated axon organization are proteins of the contactin (CNTN) group of the immunoglobulin superfamily (IgSF) of cell adhesion molecules, namely Contactin-1 and Contactin-2 (CNTN1, CNTN2). The two contactins perform their functions through intermolecular interactions, which are crucial for myelinated axon integrity and functionality. In this review, we focus on the implication of these two molecules as well as their interactors in demyelinating pathologies in humans. At first, we describe the organization and function of myelinated axons in the central (CNS) and the peripheral (PNS) nervous system, further analyzing the role of CNTN1 and CNTN2 as well as their interactors in myelination. In the last section, studies showing the correlation of the two contactins with demyelinating pathologies are reviewed, highlighting the importance of these recognition molecules in shaping the function of the nervous system in multiple ways.

Comprehensive approaches for diagnosis, monitoring and treatment of chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is the most common chronic inflammatory neuropathy. CIDP is diagnosed according to the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) criteria, which combine clinical features with the electrophysiological evidence of demyelination. However, firstly, diagnosis is challenging, as some patients e.g. with severe early axonal damage do not fulfil the criteria. Secondly, objective and reliable tools to monitor the disease course are lacking. Thirdly, about 25% of CIDP patients do not respond to evidence-based first-line therapy. Recognition of these patients is difficult and treatment beyond first-line therapy is based on observational studies and case series only. Individualized immunomodulatory treatment does not exist due to the lack of understanding of essential aspects of the underlying pathophysiology.

Novel diagnostic imaging techniques and molecular approaches can help to solve these problems but do not find enough implementation. This review gives a comprehensive overview of novel diagnostic techniques and monitoring approaches for CIDP and how these can lead to individualized treatment and better understanding of pathophysiology.

Pathophysiology of Chronic Inflammatory Demyelinating Polyneuropathy: Insights into Classification and Therapeutic Strategy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is classically defined as polyneuropathy with symmetric involvement of the proximal and distal portions of the limbs. In addition to this "typical CIDP", the currently prevailing diagnostic criteria proposed by the European Federation of Neurological Societies and Peripheral Nerve Society (EFNS/PNS) define "atypical CIDP" as encompassing the multifocal acquired demyelinating sensory and motor (MADSAM), distal acquired demyelinating symmetric (DADS), pure sensory, pure motor, and focal subtypes. Although macrophage-induced demyelination is considered pivotal to the pathogenesis of CIDP, recent studies have indicated the presence of distinctive mechanisms initiated by autoantibodies against paranodal junction proteins, such as neurofascin 155 and contactin 1. These findings led to the emergence of the concept of nodopathy or paranodopathy. Patients with these antibodies tend to show clinical features compatible with typical CIDP or DADS, particularly the latter. In contrast, classical macrophage-induced demyelination is commonly found in some patients in each major subtype, including the typical CIDP, DADS, MADSAM, and pure sensory subtypes. Differences in the distribution of lesions and the repair processes underlying demyelination by Schwann cells may determine the differences among subtypes. In particular, the preferential involvement of proximal and distal nerve segments has been suggested to occur in typical CIDP, whereas the involvement of the middle nerve segments is conspicuous in MADSAM. These findings suggest that humoral rather than cellular immunity predominates in the former because nerve roots and neuromuscular junctions lack blood-nerve barriers. Treatment for CIDP consists of intravenous immunoglobulin (IVIg) therapy, steroids, and plasma exchange, either alone or in combination. However, patients with anti-neurofascin 155 and contactin 1 antibodies are refractory to IVIg. It has been suggested that rituximab, a monoclonal antibody to CD20, could have efficacy in these patients. Further studies are needed to validate the CIDP subtypes defined by the EFNS/PNS from the viewpoint of pathogenesis and establish therapeutic strategies based on the pathophysiologies specific to each subtype.

Chronic inflammatory demyelinating polyneuropathy associated with diabetes: a European multicentre comparative reappraisal

INTRODUCTION

The association between chronic inflammatory demyelinating polyneuropathy (CIDP) and diabetes is uncertain despite important diagnostic and management implications.

METHODS

We retrospectively analysed two European cohorts, totaling 257 patients with 'definite' or 'probable' CIDP, from Serbia and Birmingham, UK.

RESULTS

Diabetes was present at CIDP diagnosis in 25/139 (18%) subjects in the Serbian cohort and in 23/118 (19.5%) in the UK cohort. In both cohorts, diabetes prevalence was higher than local general population prevalence rates (RR: 2.09; 95% CI 1.39 to 2.95 and RR: 2.22; 95% CI 1.46 to 3.17, respectively). Considering typical CIDP only, diabetes prevalence was greater than expected in both cohorts (RR: 2.58; 95% CI 1.60 to 3.82 and RR: 2.68; 95% CI 1.71 to 3.87, respectively). CIDP with diabetes occurred later in life than CIDP without diabetes (58.96 years, SD: 11.09 vs 51.71 years, SD: 16.02; p=0.003) and presented more frequently in the typical form than in patients without diabetes (79.2% vs 61.2%; p=0.02). Baseline Inflammatory Neuropathy Cause and Treatment disability scores were similar in patients with and without diabetes (p=0.90). Proportions of treatment responders were similar in both groups (70% vs 74.9%; p=0.65), as were response amplitudes (p=0.87).

DISCUSSION

Our results, both for all CIDP and typical CIDP presentations, support a twofold increased relative risk of diabetes compared with the general population. CIDP with diabetes appears to present older and more frequently in the typical form, as compared with CIDP without diabetes. CIDP with diabetes appears similar to CIDP without diabetes in disability levels at diagnosis and probability, as well as amplitude of treatment response.

Systematic literature review of burden of illness in chronic inflammatory demyelinating polyneuropathy (CIDP)

Background

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare neurological disorder characterised by muscle weakness and impaired sensory function. The present study provides a comprehensive literature review of the burden of illness of CIDP.

Methods

Systematic literature search of PubMed, Embase, and key conferences in May 2019. Search terms identified studies on the epidemiology, humanistic burden, current treatment, and economic burden of CIDP published since 2009 in English.

Results

Forty-five full texts and nineteen conference proceedings were identified on the epidemiology (n = 9), humanistic burden (n = 7), current treatment (n = 40), and economic burden (n = 8) of CIDP. Epidemiological studies showed incidence and prevalence of 0.2–1.6 and 0.8–8.9 per 100,000, respectively, depending on geography and diagnostic criteria. Humanistic burden studies revealed that patients experienced physical and psychosocial burden, including impaired physical function, pain and depression. Publications on current treatments reported on six main types of therapy: intravenous immunoglobulins, subcutaneous immunoglobulins, corticosteroids, plasma exchange, immunosuppressants, and immunomodulators. Treatments may be burdensome, due to adverse events and reduced independence caused by treatment administration setting. In Germany, UK, France, and the US, CIDP economic burden was driven by direct costs of treatment and hospitalisation. CIDP was associated with indirect costs driven by impaired productivity.

Conclusions

This first systematic review of CIDP burden of illness demonstrates the high physical and psychosocial burden of this rare disease. Future research is required to fully characterise the burden of CIDP, and to understand how appropriate treatment can mitigate burden for patients and healthcare systems.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-09998-8) contains supplementary material, which is available to authorized users.

Selective inhibition of anti-MAG IgM autoantibody binding to myelin by an antigen-specific glycopolymer

Anti‐myelin‐associated glycoprotein (MAG) neuropathy is a disabling autoimmune peripheral neuropathy that is caused by circulating monoclonal IgM autoantibodies directed against the human natural killer‐1 (HNK‐1) epitope. This carbohydrate epitope is highly expressed on adhesion molecules such as MAG, a glycoprotein present in myelinated nerves. We previously showed the therapeutic potential of the glycopolymer poly(phenyl disodium 3‐O‐sulfo‐β‐d‐glucopyranuronate)‐(1→3)‐β‐d‐galactopyranoside (PPSGG) in selectively neutralizing anti‐MAG IgM antibodies in an immunological mouse model and ex vivo with sera from anti‐MAG neuropathy patients. PPSGG is composed of a biodegradable backbone that multivalently presents a mimetic of the HNK‐1 epitope. In this study, we further explored the pharmacodynamic properties of the glycopolymer and its ability to inhibit the binding of anti‐MAG IgM to peripheral nerves. The polymer selectively bound anti‐MAG IgM autoantibodies and prevented the binding of patients’ anti‐MAG IgM antibodies to myelin of non‐human primate sciatic nerves. Upon PPSGG treatment, neither activation nor inhibition of human and murine peripheral blood mononuclear cells nor alteration of systemic inflammatory markers was observed in mice or ex vivo in human peripheral blood mononuclear cells. Intravenous injections of PPSGG to mice immunized against the HNK‐1 epitope removed anti‐MAG IgM antibodies within less than 1 hr, indicating a fast and efficient mechanism of action as compared to a B‐cell depletion with anti‐CD20. In conclusion, these observations corroborate the therapeutic potential of PPSGG for an antigen‐specific treatment of anti‐MAG neuropathy.

Read the Editorial Highlight for this article on page 465.

Motor chronic inflammatory demyelinating polyneuropathy (CIDP) in 17 patients: Clinical characteristics, electrophysiological study, and response to treatment

Motor chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare and poorly described subtype of CIDP. We aimed to study their clinical and electrophysiological characteristics and response to treatment. From a prospective database of CIDP patients, we included patients with definite or probable CIDP with motor signs and without sensory signs/symptoms at diagnosis. Patients were considered to have pure motor CIDP (PM-CIDP) if sensory conductions were normal or to have motor predominant CIDP (MPred-CIDP) if ≥2 sensory nerve action potential amplitudes were abnormal. Among the 700 patients with CIDP, 17 (2%) were included (PM-CIDP n = 7, MPred-CIDP n = 10); 71% were male, median age at onset was 48 years (range: 13-76 years), 47% had an associated inflammatory or infectious disease or neoplasia. At the more severe disease stage, 94% of patients had upper and lower limb weakness, with distal and proximal weakness in 4 limbs for 56% of them. Three-quarters (75%) responded to intravenous immunoglobulins (IVIg) and four of five patients to corticosteroids including three of three patients with MPred-CIDP. The most frequent conduction abnormalities were conduction blocks (CB, 82%) and F-wave abnormalities (88%). During follow up, 4 of 10 MPred-CIDP patients developed mild sensory symptoms; none with PM-CIDP did so. Patients with PM-CIDP had poorer outcome (median ONLS: 4; range: 22-5) compared to MPred-CIDP (2, range: 0-4; P = .03) at last follow up. This study found a progressive clinical course in the majority of patients with motor CIDP as well as frequent associated diseases, CB, and F-wave abnormalities. Corticosteroids might be considered as a therapeutic option in resistant IVIg patients with MPred-CIDP.

Immunomodulatory and anti-oxidative effect of the direct TRPV1 receptor agonist capsaicin on Schwann cells

Background

Only few studies describe the impact of nutritive factors on chronic inflammatory demyelinating polyneuropathy (CIDP), an inflammatory disease of the peripheral nervous system. The active component of chili pepper, capsaicin, is the direct agonist of the transient receptor potential channel vanilloid subfamily member 1. Its anti-inflammatory effect in the animal model experimental autoimmune neuritis (EAN) has been previously demonstrated.

Methods

In the present study, we describe the anti-inflammatory and anti-oxidative influence of capsaicin on Schwann cells (SCs) in an in vitro setting. Hereby, we analyze the effect of capsaicin on Schwann cells’ gene expression pattern, major histocompatibility complex class II (MHC-II) presentation, and H₂O₂-induced oxidative stress. Furthermore, the effect of capsaicin on myelination was examined in a SC-dorsal root ganglia (DRG) coculture by myelin basic protein staining. Finally, in order to investigate the isolated effect of capsaicin on SCs in EAN pathology, we transplant naïve and capsaicin pre-treated SCs intrathecally in EAN immunized rats and analyzed clinical presentation, electrophysiological parameters, and cytokine expression in the sciatic nerve.

Results

In SC monoculture, incubation with capsaicin significantly reduces interferon gamma-induced MHC-II production as well as toll-like receptor 4 and intercellular adhesion molecule 1 mRNA expression. Calcitonin gene-related peptide mRNA production is significantly upregulated after capsaicin treatment. Capsaicin reduces H₂O₂-induced oxidative stress in SC in a preventive, but not therapeutic setting. In a SC-DRG coculture, capsaicin does not affect myelination rate. After intrathecal transplantation of naïve and capsaicin pre-treated SCs in EAN-immunized rats, naïve, but not capsaicin pre-treated intrathecal SCs, ameliorated EAN pathology in rats.

Conclusions

In conclusion, we were able to demonstrate a direct immunomodulatory and anti-oxidative effect of capsaicin in a SC culture by reduced antigen presentation and expression of an anti-inflammatory profile. Furthermore, capsaicin increases the resistance of SCs against oxidative stress. A primary effect of capsaicin on myelination was not proven. These results are in concordance with previous data showing an anti-inflammatory effect of capsaicin, which might be highly relevant for CIDP patients.

Management challenges for chronic dysimmune neuropathies during the COVID-19 pandemic

Since March 2020, the COVID-19 pandemic has led to the need to re-think the delivery of services to patients with chronic dysimmune neuropathies. Telephone/video consultations have become widespread but have compounded concerns about objective evaluation. Therapeutic decisions need, more than ever before, to be considered in the best interests of both patients, and society, while not denying function-preserving/restoring treatment. Immunoglobulin therapy and plasma exchange, for those treated outside of the home, expose patients to the hazards of hospital or outpatient infusion centers. Steroid therapy initiation and continuation pose increased infectious risk. Immunosuppressant therapy similarly becomes highly problematic, with the risks of treatment continuation enhanced by uncertainties regarding duration of the pandemic. The required processes necessitate considerable time and effort especially as resources and staff are re-deployed to face the pandemic, but are essential for protecting this group of patients and as an integral part of wider public health actions.

Nerve ultrasound improves detection of treatment-responsive chronic inflammatory neuropathies

OBJECTIVE

To examine the diagnostic accuracy of nerve ultrasound in a prospective cohort of consecutive patients with a clinical suspicion of chronic inflammatory neuropathies, including chronic inflammatory demyelinating polyneuropathy, Lewis-Sumner syndrome, and multifocal motor neuropathy, and to determine the added value in the detection of treatment-responsive patients.

METHODS

Between February 2015 and July 2018, we included 100 consecutive incident patients with a clinical suspicion of chronic inflammatory neuropathy. All patients underwent nerve ultrasound, extensive standardized nerve conduction studies (NCS), and other relevant diagnostic investigations. We evaluated treatment response using predefined criteria. A diagnosis of chronic inflammatory neuropathy was established when NCS were abnormal (fulfilling criteria of demyelination of the European Federation of Neurological Societies/Peripheral Nerve Society) or when the degree of nerve enlargement detected by sonography was compatible with chronic inflammatory neuropathy and there was response to treatment.

RESULTS

A diagnosis of chronic inflammatory neuropathy was established in 38 patients. Sensitivity and specificity of nerve ultrasound and NCS were 97.4% and 69.4% and 78.9% and 93.5%, respectively. The added value of nerve ultrasound in detection of treatment-responsive chronic inflammatory neuropathy was 21.1% compared to NCS alone.

CONCLUSIONS

Nerve ultrasound and NCS are complementary techniques with superior sensitivity in the former and specificity in the latter. Addition of nerve ultrasound significantly improves the detection of chronic inflammatory neuropathies. Therefore, it deserves a prominent place in the diagnostic workup of chronic inflammatory neuropathies.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that nerve ultrasound is an accurate diagnostic tool to detect chronic inflammatory neuropathies.

Chronic inflammatory demyelinating polyneuropathy: update on diagnosis, immunopathogenesis and treatment

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune-mediated neuropathy typically characterised by symmetrical involvement, and proximal as well as distal muscle weakness (typical CIDP). However, there are several 'atypical' subtypes, such as multifocal acquired demyelinating sensory and motor neuropathy (Lewis-Sumner syndrome) and 'distal acquired demyelinating symmetric neuropathy', possibly having different immunopathogenesis and treatment responses. In the absence of diagnostic and pathogenetic biomarkers, diagnosis and treatment may be difficult, but recent progress has been made in the application of neuroimaging tools demonstrating nerve hypertrophy and in identifying subgroups of patients who harbour antibodies against nodal proteins such as neurofascin and contactin-1. Despite its relative rarity, CIDP represents a significant economic burden, mostly due to costly treatment with immunoglobulin. Recent studies have demonstrated the efficacy of subcutaneous as well as intravenous immunoglobulin as maintenance therapy, and newer immunomodulating drugs can be used in refractory cases. This review provides an overview focusing on advances over the past several years.

Clinicopathological characteristics of subtypes of chronic inflammatory demyelinating polyradiculoneuropathy

OBJECTIVE

To evaluate the clinical and pathological correlations characterising each clinical subtype of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

METHODS

We assessed 106 consecutive patients who had CIDP fulfilling the European Federation of Neurological Societies and Peripheral Nerve Society criteria and had been referred for sural nerve biopsy. Patients with anti-neurofascin 155, anti-contactin 1 and anti-LM1 antibodies were excluded.

RESULTS

55 patients were classified as having typical CIDP. Regarding atypical CIDP, the multifocal acquired demyelinating sensory and motor (MADSAM) (n=15), distal acquired demyelinating symmetric (DADS) (n=16) and pure sensory (n=15) forms were major subtypes, while the pure motor (n=4) and focal (n=1) forms were rare. Nerve conduction studies revealed that distal motor latencies and F-wave latencies were markedly prolonged in the typical CIDP group but relatively preserved in the MADSAM group. Motor conduction velocity was conspicuously slowed in the DADS group, and distal motor latencies were markedly prolonged in the pure sensory group. Sural nerve biopsy specimens from patients with MADSAM, DADS and pure sensory type tended to show extreme variation in myelinated fibre density among fascicles due to focal myelinated fibre loss or onion-bulb formation, whereas patients with typical CIDP tended to show mild fascicular variation. Epineurial lymphocytic infiltration was conspicuous in cases with marked fascicular variation in myelinated fibre density.

CONCLUSIONS

Preferential involvement of distal and proximal segments and uniform pathological features in typical CIDP indicate a role of humoral factors at sites where the blood-nerve barrier is deficient. By contrast, focal lesions in MADSAM, DADS and pure sensory forms may share neuropathic mechanisms primarily affecting the nerve trunk.

Risk of osteoporosis in patients with chronic inflammatory neuropathy- a population-based cohort study

The risk of osteoporosis in patients with chronic inflammatory neuropathy (CIN) has not been evaluated in detail. We conducted a population-based case-control study nested in a retrospective cohort to analyze osteoporosis risk among patients with CIN using a nationwide database. Patients with CIN based on the Korean Classification of Disease diagnostic code were included and were matched to controls. A Cox proportional hazards regression model was used to evaluate the effect of CIN on osteoporosis. After propensity score matching, 585 CIN patients and 585 controls were selected. Patients with CIN had an increased osteoporosis risk (hazard ratio [HR] = 2.293, 95% confidence interval [CI] 1.460-3.601) compared with controls. The osteoporosis risk was higher among male patients with CIN than among male controls (HR = 5.404, 95% CI 2.252-12.969), while there were no significant differences among women. Among the CIN patients, the average daily dose of corticosteroids was higher in those who developed osteoporosis (19.6 mg [10.8-49.3]) than those who did not (16.2 mg [7.2-29.1], p = 0.001). The osteoporosis risk among CIN patients is higher than among controls. High risk of osteoporosis in male patients may indicate that osteoporosis in CIN patients results from the disease itself or related treatments.

Atypical CIDP: diagnostic criteria, progression and treatment response. Data from the Italian CIDP Database

OBJECTIVES

A few variants of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) have been described, but their frequency and evolution to typical CIDP remain unclear. To determine the frequency and characteristics of the CIDP variants, their possible evolution to typical CIDP, and treatment response.

METHODS

We applied a set of diagnostic criteria to 460 patients included in a database of Italian patients with CIDP. Clinical characteristics and treatment response were reviewed for each patient. The Kaplan-Meier curve was used to estimate the progression rate from atypical to typical CIDP.

RESULTS

At the time of inclusion, 376 (82%) patients had a diagnosis of typical CIDP while 84 (18%) had atypical CIDP, including 34 (7%) with distal acquired demyelinating symmetric neuropathy (DADS), 17 (4%) with purely motor, 17 (4%) with Lewis-Sumner syndrome (LSS) and 16 (3.5%) with purely sensory CIDP. Based on retrospective review of the symptoms and signs present at onset and for at least 1 year, 180 (39%) patients had an initial diagnosis compatible with atypical CIDP that in 96 (53%) patients evolved to typical CIDP. Mean disease duration was longer in patients evolving to typical CIDP than in those not evolving (p=0.0016). Patients with DADS and LSS had a less frequent response to immunoglobulin than those with typical CIDP, while patients with purely motor and sensory CIDP had a similar treatment response.

CONCLUSIONS

The proportion of patients with atypical CIDP varies during the disease course. DADS and LSS have a less frequent response to intravenous immunoglobulin compared with typical CIDP, raising the possibility of a different underlying pathogenetic mechanism.

Incidence and Prevalence of Chronic Inflammatory Demyelinating Polyradiculoneuropathy: A Systematic Review and Meta-Analysis

BACKGROUND

Prevalence and incidence rates of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) are required to determine the impact of CIDP on society. We aimed to estimate the prevalence and incidence of CIDP worldwide and to determine the effect of diagnostic criteria on prevalence and incidence.

METHOD

A systematic review was conducted for all published incidence and prevalence studies on CIDP until May 18, 2017. Methodological quality was assessed using the Methodological Evaluation of Observational Research checklist. We performed a random effect meta-analysis to estimate pooled prevalence and incidence rates.

RESULTS

Of the 907 studies, 11 were included in the systematic review, 5 in the meta-analysis of incidence (818 cases; 220,513,514 person-years) and 9 in the meta-analysis of prevalence (3,160 cases; 160,765,325 population). These studies had a moderate quality. The pooled crude incidence rate was 0.33 per 100,000 person-years (95% CI 0.21-0.53; I2 = 95.7%) and the pooled prevalence rate was 2.81 per 100,000 (95% CI 1.58-4.39; I2 = 99.1%). Substantial heterogeneity in incidence and prevalence across studies seems to be partly explained by using different diagnostic criteria.

CONCLUSION

These findings provide a starting point to estimate the social burden of CIDP and demonstrate the need to reach consensus on diagnostic criteria for CIDP.

Clinical and economic comparison of an individualised immunoglobulin protocol vs. standard dosing for chronic inflammatory demyelinating polyneuropathy

Background

The clinical and economic implications of an individualised intravenous immunoglobulin (IVIg) protocol for chronic inflammatory demyelinating polyneuropathy (CIDP) are unknown. Comparison with standard dosing regimens has not been performed.

Methods

We retrospectively studied 47 IVIg-treated subjects with CIDP over 4 years with an individualised, outcome-measured, dose-modifying protocol. We evaluated responder and remission rates, clinical improvement levels and dose requirements. We compared clinical benefits and costs with those reported with standard dosing at 1 g/kg every 3 weeks.

Results

The IVIg-responder rate was 83% and the 4-year remission rate was 25.6%. Mean IVIg dose requirements were 22.06 g/week (SD:15.29) in patients on ongoing therapy. Dose range was wide (5.83–80 g/week). Mean infusion frequency was every 4.34 weeks (SD:1.70) and infusion duration of 2.79 days (SD:1.15). Mean Overall Neuropathy Limitation Scale improvement was 2.54 (SD:1.89) and mean MRC sum score improvement of 12.23 (SD:7.17) in IVIg-responders. Mean modified-INCAT (Inflammatory Neuropathy Cause and Treatment) score improvement was similar (p = 0.47) and mean MRC sum score improvement greater (p < 0.001) in our cohort, compared to the IVIg-treated arm of the ICE Study. Mean drug costs were GBP 37,660/patient/year (€ 43,309) and mean infusion-related costs of GBP 17,115/patient/year (€ 19,682), totalling GBP 54,775/patient/year (€ 62,991). Compared to standard dosing using recorded weight, mean savings were of GBP 13,506/patient/year (€ 15,532). Compared to standard dosing using dosing weight, savings were of GBP 6,506/patient/year (€ 7,482).

Conclusion

Our results indicate that an individualised IVIg treatment protocol is clinically non-inferior and 10–25% more cost-effective than standard dosing regimens in CIDP.