Whole-body magnetic resonance neurography in patients with chronic inflammatory demyelinating polyneuropathy.

INTRODUCTION/AIMS: Whole-body magnetic resonance neurography (MRN) is an imaging modality that shows peripheral nerve signal change in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). We aimed to explore the diagnostic potential of whole-body MRN and its potential as a monitoring tool after immunotherapy in treatment-naïve CIDP patients. METHODS: Whole-body MRN using coronal 3-dimensional short tau inversion recovery (STIR) sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE) techniques was performed in patients being investigated for CIDP and in healthy controls. Baseline clinical neuropathy scales and electrophysiologic parameters were collected, and MRN findings were compared before and after CIDP treatment. RESULTS: We found highly concordant symmetrical thickening and increased T2 signal intensities in the brachial/lumbosacral plexus, femoral, or sciatic nerves in five of the eight patients with a final diagnosis of CIDP and none of the healthy controls. There were no treatment-related imaging changes in five patients with CIDP who completed a follow-up study. Diffuse, symmetrical thickening, and increased T2 signal in root, plexus, and peripheral nerves were found in two patients ultimately excluded due to a diagnosis of polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes (POEMS) syndrome in addition to signal changes in the muscles, bony lesions, organomegaly, and lymphadenopathy. DISCUSSION: Whole-body MRN imaging shows promise in detecting abnormalities in proximal nerve segments in patients with CIDP. Future studies evaluating the role of MRN in assessing treatment response should consider follow-up scans after treatment durations of more than 4 months.

Focal inflammatory neuropathies.

This chapter focuses on neuropathies that present with focal involvement of nerve roots, plexus, and/or peripheral nerves associated with autoimmune and inflammatory mechanisms that present with focal involvement of nerve roots, plexus and/or peripheral nerves. The clinical presentation, diagnosis, and treatment of focal autoimmune demyelinating neuropathies, focal nonsystemic vasculitic disorders (diabetic and nondiabetic radiculoplexus neuropathies, postsurgical inflammatory neuropathy, and neuralgic amyotrophy), and focal neuropathies associated with sarcoidosis and bacterial and viral infections are reviewed.

Post-surgical inflammatory neuropathy after anterior cruciate ligament repair: a case report.

BACKGROUND: Unanticipated symptoms of peripheral nerve damage following surgery are distressing to both the patient and their clinical team, including surgeons, anesthesiologists, and neurologists. The causes that are commonly considered for perioperative neuropathy can include surgical trauma, positioning-related injury, or injury related to a regional anesthetic technique. However, these cases often do not have a clear etiology and can occur without any apparent periprocedural anomalies. Postoperative inflammatory neuropathy is a more recently described, and potentially underrecognized cause of perioperative neuropathy which may improve with corticosteroid therapy. Therefore, it is an important etiology to consider early in the evaluation of perioperative neuropathy. CASE PRESENTATION: An otherwise healthy patient presented for left anterior cruciate ligament reconstruction. He underwent femoral and sciatic ultrasound-guided single-injection peripheral nerve blocks preoperatively, followed by a general anesthetic for the surgical procedure. He developed postoperative neuropathy in the sciatic distribution with both sensory and motor deficits. The patient received multi-disciplinary consultations, including neurology and pain management, and a broad differential diagnosis was considered. Based on neurological evaluation and imaging studies, a final diagnosis of post-surgical inflammatory neuropathy was made. The patient's course improved with conservative management, but immunosuppressive treatment may have been considered for a more severe or worsening clinical course. CONCLUSIONS: There are limited publications describing postoperative inflammatory neuropathy, and this case serves to illustrate a potentially under-recognized and multifactorial cause of postoperative neuropathy. Perioperative neuropathies are a complication that surgeons and anesthesiologists strive to avoid; however, prevention and treatment of this condition have been elusive. Increased reporting and investigation of postoperative inflammatory neuropathy as one cause for this complication will help to further our understanding of this potentially devastating complication.

Prevention of axonal loss after immediate dosage titration of immunoglobulin in multifocal motor neuropathy.

BACKGROUND: To evaluate whether ongoing axonal loss can be prevented in multifocal motor neuropathy (MMN) treated with immunoglobulin G (IgG), a group of patients with a median disease duration of 15.7 years (range: 8.3-37.8), treated with titrated dosages of immunoglobulins, was studied electrophysiologically at time of diagnosis and at follow-up. RESULTS: At follow-up, the Z-score of the compound motor action potential amplitude of the median, fibular, and tibial nerves and the neurological performances were determined. In seven patients with a treatment-free period of 0.3 years (0.2-0.4), there was no progression of axonal loss (p = 0.2), whereas a trend toward further axonal loss by 1.3 Z-scores (0.9-17.0, p = 0.06) was observed in five patients with a treatment-free period of 4.0 years (0.9-9.0). The axonal loss in the group with a short treatment delay was significantly smaller than in the group with a longer treatment delay (p = 0.02). Also, there was an association between treatment delay and ongoing axonal loss (p = 0.004). The electrophysiological findings at follow-up were associated with the isokinetic strength performance, the neurological impairment score, and the disability, supporting the clinical relevance of the electrophysiological estimate of axonal loss. CONCLUSION: Swift initiation of an immediately titrated IgG dosage can prevent further axonal loss and disability in continuously treated MMN patients.

Rate and characteristics of inflammatory neuropathies associated with brentuximab vedotin therapy.

BACKGROUND AND PURPOSE: Peripheral neuropathy is a frequent complication of brentuximab vedotin (BV), used in CD30+ lymphoma treatment. Classic BV-induced neuropathy (BV-CN) is a mild distal sensory axonal polyneuropathy. Severe BV-induced inflammatory neuropathies (BV-IN) have been described. BV-IN contribute to lymphoma-associated morbidity but might be immunotherapy-responsive. Our primary objective was to evaluate the rate of BV-IN. Our secondary objectives were to determine risk factors and warning signs. METHODS: We conducted a retrospective cohort study on all patients treated with BV at our center between April 2014 and September 2021. Clinical, biological, and electrophysiological data were collected. BV-induced neuropathy was defined as the occurrence of neuropathy up to 3 months after BV discontinuation. BV-IN was defined with criteria adapted from European Academy of Neurology/Peripheral Nerve Society 2021 electrodiagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy. Other neuropathies were classified as BV-CN. RESULTS: Among 83 patients, 41 (49%) developed neuropathy: 35 BV-CN and 6 BV-IN. Thus, the rate of BV-IN was 7.2%. Compared to patients with BV-CN, no predisposing factor was identified. However, patients with BV-IN more frequently presented muscle weakness (67% vs. 5.7%, p < 0.05), gait disorders (83% vs. 20%, p < 0.05), or acute or subacute onset (67% vs. 14%, p < 0.05). BV-IN was frequently more severe (Common Terminology Criteria for Adverse Events grade ≥3; 50% vs. 0%, p < 0.05). Four patients were treated with immunotherapy. CONCLUSIONS: Brentuximab vedotin-induced neuropathy is an overlooked complication. Based on four easily identifiable "red flags", we provide an algorithm to help non-neurologist physicians that care for BV-treated patients to detect BV-IN. The aim of the algorithm is to decrease the diagnostic and management delay of this disabling neuropathy.

High-dose pharmaceutical-grade biotin in patients with demyelinating neuropathies: a phase 2b open label, uncontrolled, pilot study.

BACKGROUND: We proposed to investigate high-dose pharmaceutical-grade biotin in a population of demyelinating neuropathies of different aetiologies, as a proof-of-concept. METHODS: Phase IIb open label, uncontrolled, single center, pilot study in 15 patients (three groups of five patients) with chronic demyelinating peripheral neuropathy, i.e. chronic inflammatory demyelinating polyradiculoneuropathy, anti-myelin-associated glycoprotein neuropathy and Charcot-Marie-Tooth 1a or 1b. The investigational product was high-dose pharmaceutical-grade biotin (100 mg taken orally three times a day over a maximum of 52 weeks. The primary endpoint was a 10% relative improvement in 2 of the following 4 electrophysiological variables: motor nerve conduction velocity, distal motor latency, F wave latency, duration of the compound muscle action potential. The secondary endpoints included Overall Neuropathy Limitations Scale (ONLS) score, Medical Research Council (MRC) sum score, Inflammatory Neuropathy Cause and Treatment (INCAT) sensory sum score, 10-m walk test, 6-min walk test, posturography parameters, and nerve excitability variables. RESULTS: The primary endpoint was reached in one patient. In the full population analysis, some secondary endpoints parameters improved: MRC score, INCAT sensory sum score, 6-min walk distance, strength-duration time constant, and rheobase. There was a positive correlation between the improvement in the 6-min walk distance and the strength-duration time constant. Regarding the safety results, 42 adverse events occurred, of which three were of severe intensity but none was considered as related to the investigational product. CONCLUSIONS: Even if the primary endpoint was not met, administration of high-dose pharmaceutical-grade biotin led to an improvement in various sensory and motor parameters, gait abilities, and nerve excitability parameters. The tolerance of the treatment was satisfactory. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02967679; date 2016/12/05.

Acute/chronic inflammatory polyradiculoneuropathy.

Autoimmune neuropathy may present acutely or with a more progressive and/or relapsing and remitting course. Acute inflammatory neuropathy or Guillain-Barré syndrome (GBS) has variable presentations but by far the most common is acute inflammatory demyelinating polyradiculoneuropathy which is characterized by rapidly progressive proximal and distal symmetric weakness, sensory loss, and depressed reflexes. The most common chronic autoimmune neuropathy is chronic inflammatory demyelinating polyradiculoneuropathy, which in its most typical form is clinically similar to acute inflammatory demyelinating polyradiculoneuropathy (proximal and distal symmetric weakness, sensory loss, and depressed reflexes) but differs in that onset is much more gradual, i.e., over at least 8 weeks. While the majority of GBS cases result from a postinfectious activation of the immune system, presumably in a genetically susceptible host, less is understood regarding the etiopathogenesis of chronic inflammatory demyelinating polyradiculoneuropathy. Both acute and chronic forms of these inflammatory neuropathies are driven by some combination of innate and adaptive immune pathways, with differing contributions depending on the neuropathy subtype. Both disorders are largely clinical diagnoses, but diagnostic tools are available to confirm the diagnosis, prognosticate, detect variant forms, and rule out mimics. Given the autoimmune underpinnings of both disorders, immunosuppressive and immunomodulating treatments are typically given in both diseases; however, they differ in their response to treatment.

Guillain-Barré Syndrome Presenting as Painful Weakness and Edema of the Legs: A Case Report.

Guillain-Barré syndrome (GBS) is an autoimmune inflammatory polyneuropathy, which can be challenging to diagnose due to variability in the initial presenting features. Pain, flaccid paresis, motor sensory disturbance, hyporeflexia, and autonomic dysfunction are the typical manifestations, although atypical features, such as ataxia, neck stiffness, dysphagia, ophthalmoplegia, bulbar palsy, and isolated upper limb weakness, may be seen. It may also progress to fatal respiratory depression. As such, timely diagnosis and treatment are essential. We present the case of a 41-year-old man who presented with a four-day history of acute-onset bilateral lower extremity swelling, decreased motor strength, diffuse muscle pain, hyporeflexia, and absent vibratory sensation. After admission, symptoms worsened, and the patient developed new-onset swallowing difficulty and urinary retention. Neurological examination findings of hyporeflexia and flaccid paralysis, along with normal thyroid function, and the absence of cord compression on spinal MRI pointed toward the diagnosis of GBS. Nerve conduction studies (NCS) and concentric electromyography (EMG) confirmed the diagnosis. The patient was treated with intravenous immune globulin (IVIG) and eventually discharged to a rehabilitation facility after a 12-day hospital stay. Later, the patient developed contractures and chronic pain consistent with post-GBS syndrome, for which we referred him for pain management and physical therapy. A rapidly progressive weakness with autonomic dysfunction should prompt suspicion of GBS and should be treated with intravenous immunoglobulins or plasma exchange without further delay.

Peripheral Nerve Ultrasound for the Differentiation between ALS, Inflammatory, and Hereditary Polyneuropathies.

Background and Objectives: Ultrasound (US) is a non-invasive tool for the in vivo detection of peripheral nerve alterations. Materials and Methods: In this study, we applied nerve US to assist the discrimination between the spectrum of amyotrophic lateral sclerosis (ALS, n = 11), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP, n = 5), and genetically confirmed Charcot-Marie-Tooth disease (CMT, n = 5). All participants and n = 15 controls without neurological diseases underwent high-resolution US of the bilateral tibial nerve. The nerve cross-sectional area (CSA) and nerve microvascular blood flow were compared between the groups and related to cerebrospinal fluid (CSF) measures, clinical symptoms, and nerve conduction studies. The analyses are part of a larger multimodal study on the comparison between US and 7 Tesla (7T) magnetic resonance neurography (MRN). Results: The patients and controls were matched with respect to their demographical data. CMT had the longest disease duration, followed by CIDP and ALS. CSA was related to age, weight, and disease duration. CSA was larger in CMT and CIDP compared to ALS and controls. The blood flow was greatest in CIDP, and higher than in CMT, ALS, and controls. In ALS, greater CSA was correlated with greater CSF total protein and higher albumin quotient. The US measures did not correlate with clinical scores or nerve conduction studies in any of the subgroups. Conclusion: Our results point towards the feasibility of CSA and blood flow to discriminate between ALS, CIDP, and CMT, even in groups of small sample size. In ALS, larger CSA could indicate an inflammatory disease subtype characterized by reduced blood-nerve barrier integrity. Our upcoming analysis will focus on the additive value of 7T MRN in combination with US to disentangle the spectrum between more inflammatory or more degenerative disease variants among the disease groups.

Multifocal motor neuropathy is not associated with altered innate immune responses to endotoxin.

OBJECTIVE: Antibody- and complement-mediated peripheral nerve inflammation are central in the pathogenesis of MMN. Here, we studied innate immune responses to endotoxin in patients with MMN and controls to further our understanding of MMN risk factors and disease modifiers. METHODS: We stimulated whole blood of 52 patients with MMN and 24 controls with endotoxin and collected plasma. With a multiplex assay, we determined levels of the immunoregulating proteins IL-1RA, IL-1ß, IL-6, IL-10, IL-21, TNF-α, IL-8 and CD40L in unstimulated and LPS-stimulated plasma. We compared baseline and stimulated protein levels between patients and controls and correlated concentrations to clinical parameters. RESULTS: Protein level changes after stimulation were comparable between groups (p > 0.05). IL-1RA, IL-1ß, IL-6 and IL-21 baseline concentrations showed a positive correlation with monthly IVIg dosage (all corrected p-values < 0.016). Patients with anti-GM1 IgM antibodies showed a more pronounced IL-21 increase after stimulation (p 0.048). CONCLUSIONS: Altered endotoxin-induced innate immune responses are unlikely to be a susceptibility factor for MMN.

Standardized Tapering off Subcutaneous Immunoglobulin in Chronic Inflammatory Demyelinating Polyneuropathy.

BACKGROUND: Attempting discontinuation of treatment in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) is recommended. However, there is no evidence based regimen for tapering off subcutaneous immunoglobulin (SCIG). This trial investigated stepwise tapering off SCIG to detect remission and the lowest effective dosage. During tapering off, frequent vs less frequent clinical evaluation was compared. METHODS: Patients with CIDP receiving a stable SCIG dosage followed a standardized tapering off regimen: 90%, 75%, 50%, 25% and 0% of the initial dose every 12th week, pending no deterioration occurred. In case of relapse during tapering off, the lowest effective dose was identified. Treatment with SCIG was registered for two years after participation. Disability score and grip strength were primary parameters. Participants were randomized to clinical evaluation every 6th week (frequent) or 12th week (less frequent). RESULTS: Fifty-five patients were included of which thirty-five relapsed. Twenty patients (36%) were able to discontinue treatment without relapse. In relapsing patients, median dosage could be reduced by 10% (range, 0-75). After two years, 18 of 20 patients were still in remission without treatment. Frequent clinical evaluation did not detect deterioration more frequently than less frequent evaluation; RR 0.5 (95% CI, 0.2-1.2) (p = 0.17). CONCLUSION: In stable CIDP patients, SCIG could be completely tapered off in 36% of the patients and only in 10% of these patients relapse occurred during the following two years. More frequent evaluation was not superior to detect deterioration.

Different binding and pathogenic effect of neurofascin and contactin-1 autoantibodies in autoimmune nodopathies.

Introduction: IgG4 autoantibodies against paranodal proteins are known to induce acute-onset and often severe sensorimotor autoimmune neuropathies. How autoantibodies reach their antigens at the paranode in spite of the myelin barrier is still unclear. Methods: We performed in vitro incubation experiments with patient sera on unfixed and unpermeabilized nerve fibers and in vivo intraneural and intrathecal passive transfer of patient IgG to rats, to explore the access of IgG autoantibodies directed against neurofascin-155 and contactin-1 to the paranodes and their pathogenic effect. Results: We found that in vitro incubation resulted in weak paranodal binding of anti-contactin-1 autoantibodies whereas anti-neurofascin-155 autoantibodies bound to the nodes more than to the paranodes. After short-term intraneural injection, no nodal or paranodal binding was detectable when using anti-neurofascin-155 antibodies. After repeated intrathecal injections, nodal more than paranodal binding could be detected in animals treated with anti-neurofascin-155, accompanied by sensorimotor neuropathy. In contrast, no paranodal binding was visible in rats intrathecally injected with anti-contactin-1 antibodies, and animals remained unaffected. Conclusion: These data support the notion of different pathogenic mechanisms of anti-neurofascin-155 and anti-contactin-1 autoantibodies and different accessibility of paranodal and nodal structures.

Chronic inflammatory neuropathies and their impact on activities and participation.

BACKGROUND: Chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN) are inflammatory neuropathies that can lead to considerable limitations in daily activities and in social participation. However, systematic evaluation of these self-reported limitations is lacking in the currently available studies. Understanding the impact of these diagnoses on patients' life is important to optimize management strategies. AIM: To systematically assess the self-reported limitations in activities and participation and determine associated factors. METHODS: A survey study was conducted in 2021 in a cohort of patients with CIDP (n = 257) and MMN (n = 148) from a university hospital. The survey included the Rasch-built Overall Disability Scale and the Utrecht Scale for Evaluation of Rehabilitation-Participation, questions addressing personal and disease-related factors and treatment. Multivariate linear regression analysis was used to determine associations with disease-related and personal factors. RESULTS: A total of 147 CIDP and 103 MMN patients responded. Limitations in activities were reported by 70.7% CIDP and 52.2% MMN patients with moderate to severe limitations in 22.4% and 5.9% patients, respectively. Participation restrictions were reported by 50% of CIDP and 40% of MMN patients, nevertheless satisfaction with participation was high. Fatigue, pain and resilience were independently associated with limitations in activities and satisfaction with participation in CIDP patients. CONCLUSIONS: Activity limitations and restrictions in participation are common in CIDP patients and to a lesser extent in MMN patients. Fatigue, pain and resilience independently contributed to perceived limitations in CIDP patients. Referral to a rehabilitation physician is warranted to address these limitations appropriately.

Post-infectious Painful Sensory Neuronopathy Following Giardia Infection Responsive to Intravenous Immunoglobulin Treatment.

Sensory neuronopathy is a rare pure sensory disorder with characteristic clinical features of early-onset ataxia and a multifocal distribution of non-length-dependent sensory deficits. Diabetes is the most common cause of length-dependent peripheral neuropathy. However, in acute to subacute presentations, conditions such as autoimmune diseases, paraneoplastic syndrome, exposure to toxins, and viral infection could be common etiologies. This report presents a patient with sensory neuronopathy following a Giardia infection. Gait disturbance, neuropathic pain, ataxia, and pseudoathetosis improved by varying degrees following the monthly maintenance of intravenous immunoglobulin (IVIG). An immune-mediated or direct pathogenic attack can explain the underlying pathogenesis behind this patient's peripheral nerve dysfunction.

Cranial nerve involvement in patients with immune-mediated neuropathy: An observational blink reflex study.

OBJECTIVE: This study aimed to assess cranial nerve involvement in a large adult cohort of patients with immune-mediated neuropathy undergoing immunoglobulin treatment by measuring blink reflex R1 latency prolongation in correlation with clinical findings and nerve conduction studies. METHODS: 104 patients underwent blink reflex examination and ulnar nerve conduction studies and were assessed by the Inflammatory Neuropathy Cause and Treatment disability score, the revised Amyotrophic lateral sclerosis functional rating scale (ALSFRS-R) and focused clinical examination. RESULTS: Prolonged R1 latencies were identified in 23 of 104 patients (22.1 %). These patients had more severe functional impairments according to the ALSFRS-R, yet only five clinically presented with bulbar dysfunction, facial- or trigeminal nerve impairment. Overall R1 latency was inversely correlated to ulnar motor conduction velocity. In preliminary follow-up assessments under continuous immunoglobulin treatment, prolonged R1 latencies partially improved. CONCLUSIONS: Cranial nerve involvement is a common feature in immune-mediated neuropathies and is associated with a more severe disease stage. Here, R1 prolongation was detected less frequently compared to previously reported untreated cohorts. SIGNIFICANCE: Blink reflex studies can detect subclinical cranial nerve involvement in immune-mediated neuropathies. Further studies are needed to evaluate the clinical utility of measuring R1 latency.

Mechanisms behind diffuse idiopathic peripheral neuropathy in humans - a systematic review.

INTRODUCTION: Diffuse peripheral neuropathy is a well-known complication of several conditions, whereas many patients have peripheral neuropathy of unknown etiology and pathophyisology. Increased knowledge of mechanisms may provide insight into enteric neuropathy with gastrointestinal dysmotility. The aim of the present systematic review was to identify mechanisms behind diffuse idiopathic peripheral neuropathies in humans. METHODS: Searches were performed in PubMed, Embase, and Web of Science. Human original and review articles, written in English, describing mechanisms behind diffuse peripheral neuropathy verified by objective examinations were intended to be studied. Articles that described animal models, well-described hereditary diseases, drug-induced neuropathy, pain syndromes, malnutrition, and local neuropathy were excluded. RESULTS: In total, 4712 articles were identified. After scrutinizing titles and abstracts, 633 remained and were studied in full text. After the removal of articles not fulfilling inclusion or exclusion criteria, 52 were finally included in this review. The most frequently described neuropathy was diabetic neuropathy, with a wide range of mechanisms involving mitochondrial dysfunction such as oxidative stress and inflammation. Microvascular changes in diabetes and vasculitis lead to ischemia and secondary oxidative stress with inflammation. Structural changes in neurons and glial cells are observed, with abnormalities in different neurotrophic factors. Neuropathy induced by autoantibodies or immunological mechanisms is described in infectious and systemic inflammatory diseases. Several ion channels may be involved in painful neuropathy. No study identified why some patients mainly develop large fiber neuropathy and others small fiber neuropathy. CONCLUSION: Metabolic and immunological factors and channelopathy may be considered in diffuse idiopathic peripheral neuropathy.

Acute Bulbar Palsy-Plus Variant of Guillain-Barré Syndrome in a 3-Year-Old Girl.

We present a case of a 3-year-old girl who rapidly developed bilateral facial palsy, dysphagia, dysphonia, areflexia, and ataxia soon after receiving an influenza vaccine. Brain and spine Magnetic resonance imaging (MRI) scans with and without contrast showed enhancement of cranial nerves III, V, VII, and X, as well as the anterior and posterior cervical spinal and cauda equina roots. cerebrospinal fluid (CSF) studies showed white blood cell count of 19 cells/cm2, glucose 81 mg/dL, and protein 116 mg/dL, with negative infectious and autoimmune labs. Serum IgM and IgG antibodies against GM1, GD1a, GD1b, GM2, GT1A, GQ1b were negative. The patient was treated with intravenous immunoglobulin, which led to a full recovery. Upon three-month follow-up, her neurologic examination demonstrated normal cranial nerves, reflexes, and gait. Her presentation was most consistent with the acute bulbar palsy plus (ABPp) variant of Guillain-Barré syndrome (GBS), a rare and challenging diagnosis especially in her age group.

Evidence base for investigative and therapeutic modalities in chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy.

Chronic inflammatory demyelinating polyneuropathy, its variants and multifocal motor neuropathy belong to a spectrum of peripheral nerve disorders with complex dysimmune disease mechanisms. Awareness of the unique clinical phenotypes but also heterogeneity between patients is vital to arrive at early suspicion and ordering appropriate tests. This includes requirements for optimal electrodiagnostic protocol, aimed to capture sufficient electrophysiologic evidence for relevant abnormalities, a case-based approach on the eventual need to further expand the diagnostic armamentarium and correct reading of their results. Considerable phenotypical variation, diverse combinations of abnormalities found on diagnostic tests and heterogeneity in disease course and treatment response, all contribute to widespread differences in success rates on timely diagnosis and optimal treatment. We aim to provide a practical overview and guidance on relevant diagnostic and management strategies, including pitfalls and present a summary of the relevant novel developments in this field.

Dramatic clinical response to ultra-high dose IVIg in otherwise treatment resistant inflammatory neuropathies.

BACKGROUND: Intravenous immunoglobulin (IVIg) has short and long-term efficacy in both chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy with conduction block (MMNCB). There is potential for under and over-treatment if trial regimens are strictly adhered to in clinical practice where titrating dose to clinical response is recommended. METHODS: We report the response to high-dose IVIg (>2 g/kg/6 weeks) in a subgroup of patients with definite CIDP or MMNCB who were unresponsive to 'usual' dosing. IVIg frequency and dosing was determined for each individual by subjective and objective outcome measures for impairment, grip strength, and activity and participation. RESULTS: Six patients (three with chronic inflammatory demyelinating polyneuropathy (CIDP), three with MMN) were included. Two patients (one CIDP and one MMNCB) returned to full-time work on fractionated IVIg doses of 5 g/kg/month and 9 g/kg/month. Patient three (CIDP) failed numerous other immunosuppressants but responded to short-term fractionated 4 g/kg/month of IVIg. Patient four has severe, refractory, childhood-onset CIDP, remains stable but dependent currently on 6.9 g/kg/month of IVIg. Patients five and six, both with MMNCB, required short term 4.5-5 g/kg/month to recover significant bilateral hand strength. No IVIg-related adverse events occurred in any individual. CONCLUSIONS: These six cases demonstrate the safety and effectiveness of a treatment approach that includes individualised but evidence-based clinical assessment and, when necessary, high-doses of IVIg to restore patients' strength and ability to participate in activities of daily activities. Careful patient selection is important.

LPA1 signaling drives Schwann cell dedifferentiation in experimental autoimmune neuritis.

BACKGROUND: Lysophosphatidic acid (LPA) is a pleiotropic lipid messenger that addresses at least six specific G-protein coupled receptors. Accumulating evidence indicates a significant involvement of LPA in immune cell regulation as well as Schwann cell physiology, with potential relevance for the pathophysiology of peripheral neuroinflammation. However, the role of LPA signaling in inflammatory neuropathies has remained completely undefined. Given the broad expression of LPA receptors on both Schwann cells and cells of the innate and adaptive immune system, we hypothesized that inhibition of LPA signaling may ameliorate the course of disease in experimental autoimmune neuritis (EAN). METHODS: We induced active EAN by inoculation of myelin protein 2 peptide (P255-78) in female Lewis rats. Animals received the orally available LPA receptor antagonist AM095, specifically targeting the LPA1 receptor subtype. AM095 was administered daily via oral gavage in a therapeutic regimen from 10 until 28 days post-immunization (dpi). Analyses were based on clinical testing, hemogram profiles, immunohistochemistry and morphometric assessment of myelination. RESULTS: Lewis rats treated with AM095 displayed a significant improvement in clinical scores, most notably during the remission phase. Cellular infiltration of sciatic nerve was only discretely affected by AM095. Hemogram profiles indicated no impact on circulating leukocytes. However, sciatic nerve immunohistochemistry revealed a reduction in the number of Schwann cells expressing the dedifferentiation marker Sox2 paralleled by a corresponding increase in differentiating Sox10-positive Schwann cells. In line with this, morphometric analysis of sciatic nerve semi-thin sections identified a significant increase in large-caliber myelinated axons at 28 dpi. Myelin thickness was unaffected by AM095. CONCLUSION: Thus, LPA1 signaling may present a novel therapeutic target for the treatment of inflammatory neuropathies, potentially affecting regenerative responses in the peripheral nerve by modulating Schwann cell differentiation.