History, Diagnosis, and Management of Chronic Inflammatory Demyelinating Polyradiculoneuropathy

Animal models of immune-mediated demyelinating polyneuropathies

Immune-mediated demyelinating polyneuropathies (IMDPs) are rare disorders in which dysregulated adaptive immune responses cause peripheral nerve demyelinating inflammation and axonal injury in susceptible individuals. Despite significant advances in understanding IMDP pathogenesis guided by patient data and representative mammalian models, specific therapies are lacking. Significant knowledge gaps in IMDP pathogenesis still exist, e.g. precise antigen(s) and mechanisms that initially trigger immune system activation and identification of large population disease susceptibility factors. The initial directional cues for antigen-specific effector or autoreactive leukocyte trafficking into peripheral nerves are also unknown. An overview of current animal models, with emphasis on the experimental autoimmune neuritis and spontaneous autoimmune peripheral polyneuropathy models, is provided. Insights on the initial directional cues for peripheral nerve tissue specific autoimmunity using a novel Major Histocompatibility Complex class II conditional knockout mouse strain are also discussed, suggesting an essential research tool to study cell- and time-dependent adaptive immunity in autoimmune diseases.

The multiple roles of nerve biopsy in the diagnosis and prognosis of suspected immune neuropathies

INTRODUCTION

The value of a sural nerve biopsy for the diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is controversial. Evidence-based recommendations for its implementation are lacking. We investigated factors leading to biopsy and analyzed biopsy outcomes and consequences, assessed the predictability of biopsy outcomes through clinical parameters to avoid unnecessary biopsies, and compared results with electrophysiological and clinical severity to determine their prognostic value.

METHODS

190 sural nerve biopsies were analyzed in two cohorts. One consisted of 163 biopsies and the second of 72 biopsies from the prospective Immune-mediated Neuropathies Biomaterial and Data registry (INHIBIT). Both have an intersection of 45 patients. 75 data sets from patients without biopsy were used. Analysis of nerve conduction studies, treatment, overall disability sum score (ODSS), biopsy outcomes, and diagnosis was performed.

RESULTS

51% of biopsied patients received the diagnosis CIDP (77% fulfilled EFNS/PNS criteria), 21% were not CIDP typical, and 27% were unspecific. Biopsied patients responded less frequently to immunotherapies at time of biopsy than non-biopsied patients (p = 0.003). Immunotherapy was initiated more frequently after biopsy (p < 0.001) and more often with intravenous immunoglobulins (p < 0.0001). 76% of all biopsied patients met the electrophysiological criteria for CIDP. Sensory nerve action potential amplitudes of 0 µV still provide 73% of histological diagnostic value. Histologic signs of degeneration predicted ODSS worsening after 1 year (p = 0.028) but disease severity did not correlate with histological damage severity.

DISCUSSION

The main indication for nerve biopsy was the treatment of refractory cases of autoimmune neuropathies with the therapeutic consequence of treatment initiation or escalation. Sural biopsy also provided prognostic information. Even with extinguished sural SNAP, the biopsy can still have diagnostic value.

Exploring the depths of IgG4: insights into autoimmunity and novel treatments

IgG4 subclass antibodies represent the rarest subclass of IgG antibodies, comprising only 3-5% of antibodies circulating in the bloodstream. These antibodies possess unique structural features, notably their ability to undergo a process known as fragment-antigen binding (Fab)-arm exchange, wherein they exchange half-molecules with other IgG4 antibodies. Functionally, IgG4 antibodies primarily block and exert immunomodulatory effects, particularly in the context of IgE isotype-mediated hypersensitivity reactions. In the context of disease, IgG4 antibodies are prominently observed in various autoimmune diseases combined under the term IgG4 autoimmune diseases (IgG4-AID). These diseases include myasthenia gravis (MG) with autoantibodies against muscle-specific tyrosine kinase (MuSK), nodo-paranodopathies with autoantibodies against paranodal and nodal proteins, pemphigus vulgaris and foliaceus with antibodies against desmoglein and encephalitis with antibodies against LGI1/CASPR2. Additionally, IgG4 antibodies are a prominent feature in the rare entity of IgG4 related disease (IgG4-RD). Intriguingly, both IgG4-AID and IgG4-RD demonstrate a remarkable responsiveness to anti-CD20-mediated B cell depletion therapy (BCDT), suggesting shared underlying immunopathologies. This review aims to provide a comprehensive exploration of B cells, antibody subclasses, and their general properties before examining the distinctive characteristics of IgG4 subclass antibodies in the context of health, IgG4-AID and IgG4-RD. Furthermore, we will examine potential therapeutic strategies for these conditions, with a special focus on leveraging insights gained from anti-CD20-mediated BCDT. Through this analysis, we aim to enhance our understanding of the pathogenesis of IgG4-mediated diseases and identify promising possibilities for targeted therapeutic intervention.

Repeated Acute Exacerbations of Chronic Inflammatory Demyelinating Polyradiculoneuropathy Accompanied by Pain and Swelling in Distal Extremities

An 81-year-old man experienced acute progression of weakness in the extremities accompanied by a fever, tenderness, and swelling in distal parts of the extremities. He had flaccid tetraparesis with fasciculations and general hyporeflexia. Nerve conduction studies indicated demyelinating sensorimotor neuropathy. A cerebrospinal fluid examination revealed elevated proteins without pleocytosis. Immunological treatments were effective, but his symptoms exhibited repeated relapse and remission phases. He was diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with an acute onset. The highlight of this case is pain with inflammatory reaction recognized as red flags of CIDP, with the clinical course and electrophysiological findings compatible with CIDP.

Chronic inflammatory demyelinating polyradiculoneuropathy in a patient with systemic lupus erythematosus without systemic activity

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an uncommon subtype of peripheral neuropathy, especially in systemic lupus erythematosus (SLE). We report a case of SLE presenting with CIDP successfully treated. The patient presented with bilateral, progressive, ascending, sensory, and motor neuropathy. Electrodiagnostic tests reported active motor and sensitive demyelinating polyneuropathy, and the diagnosis of CIDP was confirmed according to the European Federation of Neurological Societies/Peripheral Nerve Society criteria. Initial management with intravenous immunoglobulin and high-dose steroids was administered, then 6-month intravenous cyclophosphamide was initiated with improvement according to clinical scales. In conclusion, CIDP in SLE is rare, reported in just 0.2%. Immunosuppressive therapy should be considered whether initial improvement is not evidenced, as seen in our case requiring cyclophosphamide; interestingly, systemic activity was in remission as the peripheral nervous system is not part of neurological compromise, and we suggest evaluating this unusual presentation into rheumatological practice.

Chronic inflammatory demyelinating polyradiculoneuropathy in patients with diabetes mellitus - treatment with intravenous immunoglobulins: A systematic review

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare disease, but it is one of the most common inflammatory neuropathies in the population. It is particularly common among patients with diabetes mellitus. This raises many problems, both with the differential diagnosis of diabetic and inflammatory neuropathy, as well as the choice of treatment. Intravenous immunoglobulin (IVIG) is one of the therapeutic options. There is evidence for the effectiveness of IVIG in treating about two-thirds of patients. However, no review has been published to date systematising studies evaluating the response to IVIG treatment in patients with CIDP and coexisting diabetes.

METHODS

The present study is based on the PRISMA statement and is registered at PROSPERO (CRD42022356180). The study included searches of the databases of MEDLINE, ERIC, CINAHL Complete, Academic Search Ultimate and Health Source: Nursing/Academic Edition, finally including seven original papers evaluating a total of 534 patients in the review. The main inclusion criteria were the presence of a group of patients with CIDP and comorbid diabetes in the study.

RESULTS

The systematic review showed a lower efficacy of IVIG treatment among patients with coexisting diabetes compared with idiopathic CIDP (61 % vs 71 %). In addition, the presence of conduction blocks on neurography and shorter disease duration proved to be significant factors improving response to treatment.

CONCLUSIONS

Current scientific data do not allow for strong recommendations on the choice of treatment for CIDP. A randomised, multicentre study evaluating the efficacy of different therapeutic approaches to this disease entity needs to be planned.

A Budget Impact Model of Maintenance Treatment of Chronic Inflammatory Demyelinating Polyneuropathy with IgPro20 (Hizentra) Relative to Intravenous Immunoglobulin in the United States

BACKGROUND

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare, progressive autoimmune disease causing peripheral nervous system dysfunction. Guidelines recommend immunoglobulin (IG) therapy as an immunomodulatory agent in CIDP. Drawbacks and unmet needs with intravenous immunoglobulin (IVIG) include adverse effects and wear-off effects, along with the burden of administration based on site of care. Subcutaneous administration of Hizentra, a subcutaneous immunoglobulin (SCIG) reduces patient burden by allowing self-administration outside the hospital setting and has fewer adverse events (AEs).

OBJECTIVE

We aimed to compare the expected cost of treatment and the budget impact of Hizentra compared with IVIG for maintenance treatment of CIDP in the United States.

METHODS

A decision tree model was developed to estimate the expected budget impact of maintenance treatment with Hizentra for US stakeholders. The model adopts primarily a US integrated delivery network perspective and, secondarily, a commercial perspective over a 1-year time horizon. Pharmacy costs were based on a payment mix of average sales price (73%), wholesale acquisition cost (2%), and average wholesale price (25%). Costs in the model reflect 2022 US dollars. In accordance with the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines and recommendations for budget impact modeling, no discounting was performed. The PATH clinical study of Hizentra maintenance in CIDP was used to determine clinical inputs for relapse rates at initial assessment (24 weeks) and at 52 weeks for Hizentra. The ICE clinical study of Gamunex maintenance in CIDP was the basis of relapse rates for Gamunex (and other IVIGs). Literature-based estimates were obtained for infusion costs by site of care, costs of IVIG infusion-related complications, and significant IVIG AE rates. Hizentra AE rates from the US Hizentra prescribing information were assessed but were not included in the model as the AEs in CIDP were mild, easily treated, and self-limited. Sensitivity analyses and scenario analyses were conducted to evaluate variations from the base case.

RESULTS

The model showed that a Hizentra starting dose of 0.2 g/kg is expected to result in annual cost savings of US$32,447 per patient compared with IVIG. For a hypothetical 25-million-member plan, the budget impact of a 10% market share shift from IVIG to Hizentra is expected to result in savings of US$2,296,235.

CONCLUSION

This analysis projects that Hizentra is likely associated with favorable economic benefit compared with IVIG in managing CIDP.

A case report of neuronal intranuclear inclusion disease with paroxysmal peripheral neuropathy-like onset lacking typical signs on diffusion-weighted imaging

Background

Neuronal intranuclear inclusion disease (NIID) is a slowly progressive neurodegenerative disease characterized by eosinophilic hyaline intranuclear inclusions and the GGC repeats in the 5'-untranslated region of NOTCH2NLC. The prevalent presence of high-intensity signal along the corticomedullary junction on diffusion-weighted imaging (DWI) helps to recognize this heterogeneous disease despite of highly variable clinical manifestations. However, patients without the typical sign on DWI are often misdiagnosed. Besides, there are no reports of NIID patients presenting with paroxysmal peripheral neuropathy-like onset to date.

Case presentation

We present a patient with NIID who suffered recurrent transient numbness in arms for 17 months. Magnetic resonance imaging (MRI) showed diffuse, bilateral white matter lesions without typical subcortical DWI signals. Electrophysiological studies revealed mixed demyelinating and axonal sensorimotor polyneuropathies involving four extremities. After excluding differential diagnosis of peripheral neuropathy through body fluid tests and a sural nerve biopsy, NIID was confirmed by a skin biopsy and the genetic analysis of NOTCH2NLC.

Conclusion

This case innovatively demonstrates that NIID could manifest as paroxysmal peripheral neuropathy-like onset, and addresses the electrophysiological characteristics of NIID in depth. We broaden the clinical spectrum of NIID and provide new insights into its differential diagnosis from the perspective of peripheral neuropathy.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy and Diabetes: A Case Report

We present a case of a 42-year-old female living with poorly controlled diabetes who presented with a nine-month evolution of ataxic gait, reduced motor and sensitive function of lower and upper limbs, and postural anesthesia of fingers, feet, and toes. Deep tendon reflexes were abolished in the lower limbs and markedly diminished in the upper limbs. Cerebrospinal fluid (CSF) analysis showed a high protein level, and both imaging and serologic studies were normal. Although she had a previous electrophysiologic study showing distal symmetric polyneuropathy (DSPN) with an axonal lesion, nerve conduction studies were repeated, and a diagnosis of chronic inflammatory demyelinating polyneuroradiculopathy (CIDP) was made. According to the state of the art, intravenous immunoglobulin (IVIg) was started. The patient’s Inflammatory Neuropathy Cause and Treatment (INCAT) score and Medical Research Council (MRC) Sum Score both improved after two cycles. Unfortunately, symptoms quickly recurred, and corticosteroids were introduced to try to delay symptom recurrence, although it worsened diabetes control. Later, IVIg was stopped due to nephrotic syndrome, and immunosuppression was initiated. CIDP is a potentially treatable disease, but the diagnosis must be made as soon as possible to start therapy and reduce sequelae. Neuropathy in patients living with diabetes is common, but patients must be monitored closely to enable a correct diagnosis and adequate treatment.

Cyclophosphamide for Treatment of Refractory Chronic Inflammatory Demyelinating Polyradiculoneuropathy: A Systematic Review and Meta-analysis

PURPOSE

This study evaluates the tolerability and efficacy of cyclophosphamide (CYC) for the treatment of refractory chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

METHODS

We searched PubMed, Embase, Cochrane Library, and 2 Chinese databases (Chinese National Knowledge Infrastructure and SinoMed) for studies published between database inception and September 30, 2021. Articles obtained using the appropriate keywords were independently selected by 2 reviewers on the basis of the established inclusion and exclusion criteria.

FINDINGS

In total, 240 records that were eventually curtailed to 13 studies with 83 patients were retrieved and subsequently included in this evaluation. All 13 studies were included in the systematic review, 7 of which were included in the meta-analysis. The pooled estimate of the response rate was 68% (95% CI, 45%-90%). The pooled estimate of the adverse reaction rate was 8% (95% CI, 0%-15%). The disease duration before the first CYC treatment was negatively correlated with the reduction in the modified Rankin Scale score (r = -0.76, P < 0.001). However, the response rates did not differ significantly between patients of different sexes (P = 0.716) or between patients who received and those who did not receive concurrent glucocorticoids (P = 0.617).

IMPLICATIONS

CYC might be a recommended therapeutic option for patients with refractory CIDP, especially those who are unable to accept rituximab treatment. Earlier CYC treatment yields better therapeutic outcomes in patients with refractory CIDP without CYC-related contraindications.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy in Association With Concomitant Diseases: Identification and Management

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare, heterogeneous, but treatable autoimmune-mediated peripheral neuropathy characterized by demyelination. CIDP can occur independently or simultaneously with a variety of diseases such as diabetes, monoclonal gammopathy of undetermined significance (MGUS), connective tissue disease, and HIV. It is important to identify CIDP and specific peripheral neuropathies caused by these diseases; this review aims to summarize the CIDP literatures related to diabetes, MGUS, SLE, and HIV, and to be helpful for the management of such patients.

Tacrolimus treatment for relapsing-remitting chronic inflammatory demyelinating polyradiculoneuropathy: Two case reports

BACKGROUND

This study describes the efficacy of a tacrolimus treatment regimen used to treat two patients with relapsing-remitting chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

CASE SUMMARY

Two patients (17-year-old female and 27-year-old male) were enrolled in the current study and were followed up for 12 mo. The first patient was administered tacrolimus (2 mg/d) for 12 mo and prednisolone (40 mg/d) for six months. The second patient was administered tacrolimus (3 mg/d) for six months. Both patients were followed up for 12 mo and the degree of recurrent weakness or normalized motor function was monitored. In addition, nerve conduction studies and tacrolimus levels were recorded. Following tacrolimus treatment, both patients showed marked improvement in clinical outcomes. In the first patient, prednisolone treatment was successfully withdrawn after six months. Sensory as well as motor nerve conduction velocities showed evident recovery following treatment. However, conduction velocities did not completely return to normal, suggesting that electrophysiological recovery can be slower than clinical recovery.

CONCLUSION

Neither patient exhibited any adverse effects due to the tacrolimus therapy. Therefore, tacrolimus can be effective for the treatment of patients with steroid-resistant CIDP.

Chronic Inflammatory Demyelinating Polyneuropathy in Patients With Crohn's Disease on Infliximab Therapy

Crohn’s disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract that is frequently accompanied by systemic complications including peripheral neuropathies. Anti-tumor necrosis factor-alpha agents such as infliximab are an established treatment for immune-mediated diseases. However, they have been associated with adverse effects, including local reactions, infections, congestive heart failure, malignancies, and, rarely, they can cause neurological adverse effects on the central nervous system, as well as peripheral nervous system demyelination. Here, we report the case of an 80-year-old man with CD on infliximab therapy who presented with progressive weakness and numbness. A neurological examination and a nerve conduction study suggested chronic inflammatory demyelinating polyneuropathy (CIDP). The patient was started on oral corticosteroids and experienced transient improvement of his symptoms at the end of this course. Thus, CIDP could be one of the extraintestinal presentations of CD.

Peripheral polyneuropathy from electrodiagnostic tests: a 10-year etiology and neurophysiology overview

BACKGROUND

Polyneuropathies are characterized by a symmetrical impairment of the peripheral nervous system, resulting in sensory, motor and/or autonomic deficits. Due to the heterogeneity of causes, an etiological diagnosis for polyneuropathy is challenging.

OBJECTIVE

The aim of this study was to determine the main causes of polyneuropathy confirmed by electrodiagnostic (EDX) tests in a tertiary service and its neurophysiological aspects.

METHODS

This observational cross-sectional study from a neuromuscular disorders center included individuals whose electrodiagnostic tests performed between 2008 and 2017 confirmed a diagnosis of polyneuropathy. Through analysis of medical records, polyneuropathies were classified according to etiology and neurophysiological aspect.

RESULTS

Of the 380 included patients, 59.5% were male, with a median age of 43 years. The main etiologies were: inflammatory (23.7%), hereditary (18.9%), idiopathic (13.7%), multifactorial (11.1%), and diabetes (10.8%). The main electrophysiological patterns were axonal sensorimotor polyneuropathy (36.1%) and "demyelinating and axonal" sensorimotor polyneuropathy (27.9%). Axonal patterns showed greater etiological heterogeneity, with a predominance of idiopathic and multifactorial polyneuropathy, while demyelinating and "demyelinating and axonal" polyneuropathies had a significantly fewer etiologies, with a predominance of hereditary and inflammatory polyneuropathies.

CONCLUSION

The main causes of polyneuropathy confirmed by EDX test in this study were those that presented a severe, atypical and/or rapidly progressing pattern. Other causes were hereditary and those that defy clinical reasoning, such as multiple risk factors; some polyneuropathies did not have a specific etiology. EDX tests are useful for etiological diagnosis of rare polyneuropathies, because neurophysiological patterns are correlated with specific etiologies.

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.

Sensory root demyelination: Transforming touch into pain

The normal feeling of touch is vital for nearly every aspect of our daily life. However, touching is not always felt as touch, but also abnormally as pain under numerous diseased conditions. For either mechanistic understanding of the faithful feeling of touch or clinical management of chronic pain, there is an essential need to thoroughly dissect the neuropathological changes that lead to painful touch or tactile allodynia and their corresponding cellular and molecular underpinnings. In recent years, we have seen remarkable progress in our understanding of the neural circuits for painful touch, with an increasing emphasis on the upstream roles of non-neuronal cells. As a highly specialized form of axon ensheathment by glial cells in jawed vertebrates, myelin sheaths not only mediate their outstanding neural functions via saltatory impulse propagation of temporal and spatial precision, but also support long-term neuronal/axonal integrity via metabolic and neurotrophic coupling. Therefore, myelinopathies have been implicated in diverse neuropsychiatric diseases, which are traditionally recognized as a result of the dysfunctions of neural circuits. However, whether myelinopathies can transform touch into pain remains a long-standing question. By summarizing and reframing the fragmentary but accumulating evidence so far, the present review indicates that sensory root demyelination represents a hitherto underappreciated neuropathological change for most neuropathic conditions of painful touch and offers an insightful window into faithful tactile sensation as well as a potential therapeutic target for intractable painful touch.

Subcutaneous immunoglobulin treatment for chronic inflammatory demyelinating polyneuropathy

Immunoglobulin G (IgG) therapy is an established long‐term treatment in chronic inflammatory demyelinating polyneuropathy (CIDP) that is commonly administered intravenously (IVIg). The subcutaneous immunoglobulin (SCIg) administration route is a safe and effective alternative option, approved by the United States Food and Drug Administration (FDA) in 2018, for maintenance treatment of adults with CIDP. Physicians and patients alike need to be aware of all their treatment options in order to make informed decisions and plan long‐term treatment strategies. In this review, we collate the evidence for SCIg in CIDP from all published studies and discuss their implications and translation to clinical practice. We also provide guidance on the practicalities of how and when to transition patients from IVIg to SCIg and ongoing patient support. Evidence suggests that IVIg and SCIg have comparable long‐term efficacy in CIDP. However, SCIg can provide additional benefits for some patients, including no requirement for venous access or premedication, and reduced frequency of systemic adverse events. Local‐site reactions are more common with SCIg than IVIg, but these are mostly well‐tolerated and abate with subsequent infusions. Data suggest that many patients prefer SCIg following transition from IVIg. SCIg preference may be a result of the independence and flexibility associated with self‐infusion, whereas IVIg preference may be a result of familiarity and reliance on a healthcare professional for infusions. In practice, individualizing maintenance dosing based on disease behavior and determining the minimally effective IgG dose for individuals are key considerations irrespective of the administration route chosen.

Rare diabetic neuropathies: It is not only distal symmetrical polyneuropathy

The prevalence of diabetes mellitus is increasing at an epidemic level, leading to a consequent increase of its chronic complications, including neuropathy. Diabetic neuropathy constitutes a heterogeneous group of disorders with distinct clinical presentations and pathophysiological mechanisms. These distinct forms may be categorised according to their clinical presentation as symmetrical (distal symmetrical polyneuropathy, autonomic and acute sensory neuropathy) and focal or multifocal (radiculoplexus neuropathies, entrapment syndromes, cranial palsies and other mononeuropathies). Additionally, people with diabetes may have neuropathies due to causes other than diabetes. The commonest forms of diabetic neuropathy are distal symmetrical polyneuropathy and autonomic neuropathy. However, clinicians should be aware that people with diabetes may suffer from less common forms of neuropathy and should be able to recognise their symptoms and signs. The recognition of the rare diabetic neuropathies is crucial, as they often lead to different clinical outcomes and require different management. The aim of the present narrative, non-systematic review is to outline the rare types of diabetic neuropathies.

Neurofascin antibodies in chronic inflammatory demyelinating polyradiculoneuropathy: from intrinsic genetic background to clinical manifestations

There are bunch of autoantibodies, particularly autoantibodies against proteins located at the node of Ranvier, have been discovered and transformed the clinical management of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Neurofascin (NF) plays an important role in both the nodal and paranodal regions of the node of Ranvier. In this review, we focus on the two characteristic forms of neurofascin: NF186 and NF155, comparing the similarities and differences between them, reviewing the current knowledge on genetic backgrounds, pathogenesis, clinical manifestations, and management of patients with anti-neurofascin positive CIDP. Autoantibodies against neurofascin were mainly IgG4 isotype. Mutation of NFASC gene in human causes severe neurodevelopment disorders, and HLA DRB1*15 may be a strong risk factor for the development of anti-NF155 antibodies. Motor impairment, sensory ataxia, and tremor were the typical presentations of patients with anti-NF155+ CIDP, while tetraplegia and cranial nerve involvement were more common in patients with anti-NF186+ CIDP. Recent studies have depicted a relatively clear picture of anti-NF155+ CIDP, and the strong clinical correlation of NF186 with CIDP remains unclear. The genetic background of neurofascin will assist in future explorations.

CSF sphingomyelin: a new biomarker of demyelination in the diagnosis and management of CIDP and GBS

OBJECTIVE

To validate sphingomyelin (SM) dosage in the cerebrospinal fluid (CSF) of patients affected by chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and Guillain-Barré syndrome (GBS) as a reliably assessable biomarker.

METHODS

We prospectively enrolled 184 patients from six Italian referral centres, in whom CSF SM levels were quantified by a fluorescence-based assay optimised and patented in our laboratory.

RESULTS

We confirmed increased levels of SM in the CSF of patients affected by typical CIDP (n=35), atypical CIDP (n=18) and acute inflammatory demyelinating polyradiculoneuropathy, AIDP (n=12) compared with patients affected by non-demyelinating neurological diseases, used as controls (n=85) (p<0.0001, p=0.0065 and p<0.0001, respectively). In patients with CIDP classified for disease stage, SM was higher in active CIDP compared with both controls and stable CIDP (p<0.0001), applying for a selective tool to treatment tailoring or withdrawal. SM was also increased in AIDP compared with axonal GBS, discerning the demyelinating from axonal variant of the disease. SM did not correlate with CSF protein levels, stratifying patients independently from commonly used CSF indexes, and displaying high specificity to avoid potential misdiagnosis. Finally, SM correlated with the main clinical scores and some neurophysiological parameters in patients with CIDP and AIDP.

CONCLUSIONS

CSF SM is a diagnostic and staging wet biomarker for acquired demyelinating neuropathies and may effectively improve the management of patients affected by GBS and CIDP.

Neuromuscular amyloidosis: Unmasking the master of disguise

Amyloidosis refers to an etiologically heterogeneous group of protein misfolding diseases, pathologically characterized by extracellular amyloid fibrils producing congophillic amorphous deposits in organs and tissues, which may lead to severe organ dysfunction and mortality. Clinical presentations vary and are often nonspecific, depending on what organs or tissues are affected. In systemic amyloidosis, the peripheral nervous system is commonly affected, whereas the skeletal muscles are only rarely involved. Immunoglobulin light chain (AL) amyloidosis and hereditary transthyretin (ATTRv) amyloidosis are the most frequent types of systemic amyloidosis involving the neuromuscular system. Localized amyloidosis can occur in skeletal muscle, so-called isolated amyloid myopathy. Amyloid neuropathy typically involves small myelinated and unmyelinated sensory and autonomic nerve fibers early in the course of the disease, followed by large myelinated fiber sensory and motor deficits. The relentlessly progressive nature with motor, painful sensory and severe autonomic dysfunction, profound weight loss, and systemic features are distinct characteristics of amyloid neuropathy. Amyloid myopathy presentation differs between systemic amyloidosis and isolated amyloid myopathy. Long-standing symptoms, distal predominant myopathy, markedly elevated creatine kinase level, and lack of peripheral neuropathy or systemic features are highly suggestive of isolated amyloid myopathy. In ATTR and AL amyloidosis, early treatment correlates with favorable outcomes. Therefore, awareness of these disorders and active screening for amyloidosis in patients with neuropathy or myopathy are crucial in detecting these patients in the everyday practice of neuromuscular medicine. Herein, we review the clinical manifestations of neuromuscular amyloidosis and provide a diagnostic approach to this disorder.

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.

Application of CMAP scan for the evaluation of patients with chronic inflammatory demyelinating polyneuropathy: a prospective study

AIMS

We aimed to assess the compound muscle action potential (CMAP) scan in the follow-up of chronic inflammatory demyelinating polyneuropathy (CIDP) patients and investigate the correlation of CMAP scan parameters with functional and standard electrodiagnostic tests.

METHODS

We evaluated four parameters of abductor pollicis brevis (APB) CMAP scan (i.e., step numbers, step percentage, S10, S90), functional measures (e.g., Medical Research Council Sum Scores), and electrodiagnostic tests, including nerve conduction study (NCS) and motor NCS of the median nerve in the baseline and after six months of treatment.

RESULTS

Twenty patients completed baseline clinical and electrodiagnostic studies. However, sixteen patients completed the follow-up study. The median of step numbers at baseline was 3.5 (2-4.2), which decreased to 2.5 (0-3) (p = 0.005). After the treatment, step percentage reduced from 28.6 (23.9-38.7) to 13.4 (0-23.6) (p = 0.001). The scores obtained from the clinical scales showed significant recovery of most of the functions, while the alterations of NCSS and NCS of the median nerve were not significant.

CONCLUSIONS

We found a significant reduction in step number and step percentage after follow-up. This alteration was not reflected in standard electrodiagnostic values. The improvement of functional scales alongside the CMAP scan parameters suggests that the CMAP scan could be considered an appropriate outcome measurement in research and clinical fields.

Elevated levels of NLRP3 inflammasome in serum of patients with chronic inflammatory demyelinating polyradiculoneuropathy are associated with disease severity

This study aims to compare the levels of NLRP3 inflammasome and its related cytokines (IL-1β, IL-6, and IL-17), in serum and cerebrospinal fluid (CSF) of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), non-inflammatory chronic polyneuropathy, and functional neurological disorders. The results showed elevated NLRP3 inflammasome, IL-1β, IL-6, and IL-17 levels in serum but not in CSF of CIDP, compared to the other groups. Moreover, there was a positive correlation between NLRP3 inflammasome level and each cytokine. We also found a positive correlation between serum NLRP3 inflammasome level and disease severity in CIDP patients. Taken together, these results suggested that NLRP3 inflammasome could act as a potential biomarker to diagnose CIDP and assess the severity of the disease.

Successful Nucleoside Analog and Corticosteroid Therapy for Chronic Inflammatory Demyelinating Polyneuropathy in a Patient With Hepatitis B Virus Liver Cirrhosis

Here, we describe the case of a 44-year-old man with chronic hepatitis B virus (HBV) infection, who was admitted with progressive muscle weakness and paresthesia in all extremities. He showed slight icterus. Positive HBV e-antigen test, significant HBV-deoxyribonucleic acid load, hypoalbuminemia, hyperbilirubinemia, mild ascites, and demyelinating peripheral axonal lesions in both sensory and motor nerves led to the diagnosis of Child-Pugh class B HBV cirrhosis with chronic inflammatory demyelinating polyneuropathy. Oral lamivudine, intravenous steroids, calcium, and vitamin D therapy led to a significant recovery of muscle strength within 6 weeks and a gradual return to normal after 24 weeks.

Treating PMP22 gene duplication-related Charcot-Marie-Tooth disease: the past, the present and the future

Charcot-Marie-Tooth (CMT) disease is the most frequent inherited neuropathy, affecting 1/1500 to 1/10000. CMT1A represents 60%-70% of all CMT and is caused by a duplication on chromosome 17p11.2 leading to an overexpression of the Peripheral Myelin Protein 22 (PMP22). PMP22 gene is under tight regulation and small changes in its expression influences myelination and affect motor and sensory functions. To date, CMT1A treatment is symptomatic and classic pharmacological options have been disappointing. Here, we review the past, present, and future treatment options for CMT1A, with a special emphasis on the highly promising potential of PMP22-targeted small interfering RNA and antisense oligonucleotides.

Chronic inflammatory demyelinating polyradiculoneuropathy associated with systemic lupus erythematosus

BACKGROUND

Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) is an uncommon subtype of peripheral neuropathy (PN) and especially when associated with systemic lupus erythematosus (SLE). There are few reports characterizing PN-associated to SLE, in particular CIDP. This study reviewed the frequency and profile of SLE-related CIDP in our cohort and in the literature and propose a treatment scheme for CIDP associated with SLE.

METHOD

We reviewed our database to identify patients with CIDP and SLE. The literature was also reviewed following the guidelines of PRISMA and using the terms "Polyradiculoneuropathy", "Chronic inflammatory demyelinating polyradiculoneuropathy", "CIDP", "Systemic lupus erythematosus", "SLE", "Autoimmune diseases of the nervous system" until December 2019. Selected articles were published in English.

RESULTS

We identified 3 patients with SLE and CIDP in our cohort of 1,349 patients with SLE (0.2%). All patients were female, aged between 30 and 44 years and 2 (66.7%) had active disease in other organs. In the literature, we identified additional 16 patients. A predominance of women with disease activity, specially nephritis and hematological involvement, was observed. Treatment schemes are diverse, including corticosteroids and immunosuppressive drugs.

CONCLUSION

Although rare, CIDP has increased frequency in SLE. Women and younger age should rise suspicion of an underlying autoimmune disease. We suggest that CIDP should be included as a possible neuropsychiatric manifestation in SLE.

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.

COVID-19 as a Trigger of Recurrent Guillain-Barré Syndrome

Coronavirus 2019 (COVID-19) has been reported to trigger Guillain-Barré syndrome (GBS). While uncommon, recurrent GBS (rGBS) episodes, triggered by antecedent viral infections, have been reported in a small proportion of GBS patients, here we describe a patient with a recurrent case of GBS, occurring secondary to COVID-19 infection. Before this patient's episode, he had two prior GBS flares, each precipitated by a viral infection followed by complete recovery besides intermittent paresthesias. We also consider the nosology of this illness in the spectrum of rGBS and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP), with their differing natural histories, prognosis, and therapeutic approaches. For patients who have a history of inflammatory demyelinating polyradiculopathies who develop COVID-19, we recommend close observation for neurologic symptoms over the next days and weeks.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy and Its Variants

PURPOSE OF REVIEW

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and its variants comprise a group of immune-mediated neuropathies with distinctive clinical presentations and electrodiagnostic features. Prompt recognition of these treatable disorders is mandatory as delays result in significant disability and morbidity. This article highlights the clinical presentation, pathophysiology, diagnostic evaluation, and treatment approach of these polyneuropathies.

RECENT FINDINGS

The spectrum of CIDP is expanding with the recent characterization of neuropathies associated with nodal and paranodal antibodies. These neuropathies are distinguished by their unique presentations and are often refractory to IV immunoglobulin (IVIg) therapy. Subcutaneous immunoglobulins have recently been approved as a treatment option for CIDP and join corticosteroids, IVIg, and plasma exchange as first-line treatment.

SUMMARY

CIDP is characterized by progressive symmetric proximal and distal weakness, large fiber sensory loss, and areflexia, with clinical nadir reached more than 8 weeks after symptom onset. Autoimmune demyelinating neuropathies fall on a continuum, with differences in the type of nerve fibers affected and pattern of deficits. Distinguishing between typical CIDP and its variants allows for selection of the most appropriate treatment.

Chronic inflammatory demyelinating polyradiculoneuropathy-Diagnostic pitfalls and treatment approach

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is characterized by progressive weakness and sensory loss, often affecting patients' ability to walk and perform activities of daily living independently. With the lack of a diagnostic biomarker, the diagnosis relies on clinical suspicion, clinical findings, and the demonstration of demyelinating changes on electrodiagnostic (EDx) testing and nerve pathology. As a result, patients can often be misdiagnosed with CIDP and unnecessarily treated with immunotherapy. Interpreting the EDx testing and cerebrospinal fluid findings in light of the clinical phenotype, recognizing atypical forms of CIDP, and screening for CIDP mimickers are the mainstays of the approach to patients suspected of having CIDP, and are detailed in this review. We also review the currently available treatment options, including intravenous immunoglobulin (IVIg), corticosteroids (CCS), and plasma exchange (PE), and discuss how to approach treatment-refractory cases. Finally, we emphasize the need to adopt objective outcome measures to monitor treatment response.

Expanding the Role of the Pharmacist: Immunoglobulin Therapy and Disease Management in Neuromuscular Disorders

Immunoglobulin G (IgG) is a commonly used treatment for chronic neuromuscular disorders (NMDs), such as chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy. IgG therapy has also shown promise in treating other NMDs including myasthenia gravis, polymyositis, and dermatomyositis. IgG is administered as either intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg), with SCIg use becoming more popular due to the treatment burden associated with IVIg. IVIg requires regular venous access; long infusions (typically 4-6 hours); and can result in systemic adverse events (AEs) for some patients. In contrast, SCIg can be self-administered at home with shorter infusions (approximately 1 hour) and fewer systemic AEs. As patient care shifts toward home-based settings, the role of the pharmacist is paramount in providing a continuation of care and acting as the bridge between patient and clinic. Pharmacists with a good understanding of current recommendations, dosing strategies, and administration routes for IgG therapy are best placed to support patients. The aims of this review are to highlight the evidence supporting IgG therapy in the treatment of NMDs and provide practical information on patient management and IVIg/SCIg dosing in order to guide pharmacists on optimizing clinical outcomes and patient care.

Long-term treatment with subcutaneous immunoglobulin in patients with chronic inflammatory demyelinating polyradiculoneuropathy: a follow-up period up to 7 years

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is a rare and heterogeneous acquired sensory-motor polyneuropathy with autoimmune pathogenesis. Intravenous immunoglobulins (IVIG) are a well-established therapy for CIDP: it is well known that at least two-thirds of these patients need these infusions for several years. More recently, Subcutaneous Immunoglobulins (SCIg) have been proved to be effective: this finding has been confirmed either in isolated cases or in few randomized trials. However, it appeared that the longest SCIg treatment follow up lasted no longer than 48 months. We report herein the results of a long-term SCIg treatment with a follow up period up to 7 years (84 months), considering safety, tolerability and patients’ perception of SCIg treatment in a CIDP population. We studied 17 patients (10 M; 7 F) with a diagnosis of CIDP, defined according to the EFNS/PNS criteria, successfully treated with IVIG every 4/6 weeks before being switched to SCIg treatment. Clinical follow-up included, apart from a routinely clinical assessment, the administration of Medical Research Council (MRC) sum-score, the Overall Neuropathy Limitation Scale (ONLS) and the Life Quality Index questionnaire (LQI). The results showed that, in the majority of this pre-selected group of CIDP patients (16/17), SCIg were well tolerated and were preferred over IVIG. Strength and motor functions remained stable or even improved during the long term follow-up (up to 84 months) with benefits on walking capability and resistance, manual activity performances and fatigue reduction.

Distinguish CIDP with autoantibody from that without autoantibody: pathogenesis, histopathology, and clinical features

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is considered to be an immune-mediated heterogeneous disease involving cellular and humoral immunity. In recent years, autoantibodies against nodal/paranodal protein neurofascin155 (NF155), neurofascin186 (NF186), contactin-1 (CNTN1), and contactin-associated protein 1 (CASPR1) have been identified in a small subset of patients with CIDP, which disrupt axo-glial interactions at nodes/paranodes. Although CIDP electrodiagnosis was made in patients with anti-nodal/paranodal component autoantibodies, macrophage-induced demyelination, the characteristic of typical CIDP, was not observed. Apart from specific histopathology, the pathogenic mechanisms and clinical manifestations of CIDP with autoantibody are also distinct. We herein compared pathogenesis, histopathology, clinical manifestations, and therapeutic response in CIDP with autoantibody vs. CIDP without autoantibody. CIDP with autoantibodies should be considered as an independent disease entity, not a subtype of CIDP due to many differences. They possibly should be classified as CIDP-like chronic nodo-paranodopathy, which can better characterize these disorders, help diagnose and make the most effective therapeutic decisions.

Neuraxial Anesthesia and Lower Extremity Peripheral Nerve Blocks for Ankle Surgery in a Patient With Chronic Inflammatory Demyelinating Polyneuropathy: A Case Report

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare autoimmune disease that targets the peripheral nervous system. The literature on the use of regional anesthesia in CIDP is limited. We report a patient with CIDP who received a combined spinal-epidural (CSE) and saphenous and popliteal peripheral nerve blocks (PNBs) for ankle surgery. The CSE and PNBs resolved without incident. On approximately the fourth postoperative day, the patient reported a worsening of baseline CIDP symptoms in all extremities. Given the diffuse presentation, the CIDP exacerbation was attributed to the perioperative stress response. The exacerbation improved by 4 months postoperatively.

Intravenous immunoglobulin therapy: a snapshot for the internist

Intravenous immunoglobulins are the cornerstone for the treatment of primary humoral immunodeficiencies and may be used for a great number of other autoimmune, neurological and hematological conditions as well. Given their wide application, the possibility of running across a patient who needs this kind of therapy is becoming increasingly common. Generally, intravenous immunoglobulins are well tolerated. However, numerous adverse reactions ranging from mild to severe have been reported and linked to patient- and product-related factors. For all these reasons, we present herein a comprehensive review of the on- and off-label applications of intravenous immunoglobulins and provide a guide for the internist how to minimize the risk of adverse reactions and manage them.

Conductive hearing loss in chronic inflammatory demyelinating polyneuropathy (CIDP): A case report

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a progressive autoimmune disorder that targets peripheral nerves. It commonly presents with motor-predominant dysfunction and enlargement of cranial nerves. With regards to hearing loss, a few cases of sensorineural loss have been described. We present a novel case of conductive hearing loss caused by a mass on the tympanic segment of the facial nerve in the setting of CIDP.