Chronic Inflammatory Demyelinating Polyneuropathy Patients Research Articles

Practical electrodiagnostic value of F-wave studies in chronic inflammatory demyelinating polyneuropathy

ObjectivesTo ascertain the practical electrodiagnostic value of F-waves in chronic inflammatory demyelinating polyneuropathy (CIDP). MethodsWe evaluated the diagnostic utility of F-waves in 18 prospectively-recruited patients with typical CIDP. Minimum/maximum/mean F-wave latencies, F-wave chronodispersion and F-wave persistence, were determined in median/ulnar/fibular/tibial nerves in patients and compared to controls with axonal neuropathy. ResultsAll latencies were significantly more delayed in CIDP patients. F-wave chronodispersion was significantly greater in median and ulnar nerves and F-wave persistence significantly more reduced in tibial nerves in CIDP patients. Use of these supplementary F-wave parameters was of value in identifying CIDP nerves. However F-wave studies were only of additional benefit to other demyelinating parameters in about 15% of all studied CIDP nerves. ConclusionsF-waves may be diagnostically helpful in CIDP in a minority of nerves without other nerve conduction abnormalities. Analysis of F-wave chronodispersion in upper limb nerves and possibly of F-wave persistence in tibial nerves, may add value to basic minimum F-wave latency studies. SignificanceThese results suggest F-wave analysis may not need to be systematic, for all nerves, in patients with suspected CIDP, especially those intolerant to electrical stimulation. Chronodispersion and persistence may be helpful parameters to consider in addition to minimum latency.

The Cytokine Profile of Chronic Inflammatory Demyelinating Polyneuropathy (P06.134)

Objective: To determine cytokine profile of chronic inflammatory demyelinating polyneuropathy (CIDP). Background An increased pro-inflammatory cytokines have been reported after intracellular analysis of T lymphocytes derived from CIDP patients. Design/Methods: We analyzed the cytokine profile of plasma samples from 8 patients with CIDP and compared it to the profile obtained from plasma samples from 8 adult healthy subjects with MILLIPLEX MAP High Sensitivity Human Cytokine Panel (Millipore, Billerica MA 01821). We analyzed the sample for 3 anti-inflammatory cytokines (IL10, IL13, IL4) and 11 pro-inflammatory cytokines (IL2, IL5, IL6, IL7, IL8, IL-1β, TNF α, MCP 1, IFN-γ, GM CSF). Results: The concentration of the following cytokines was significantly higher in the CIDP samples compared to the concentration in samples from healthy subjects: IL10 (3.511 pg/ml versus 1.022 pg/ml, p p p p p p Conclusions: Both pro and anti-inflammatory cytokines are significantly increased in CIDP patients. Work is progress to determine whether a pattern of unbalance between pro and anti inflammatory cytokines and whether IL4 could be used as a specific marker for CIDP. Supported by: Talecris Invetigator initiated award. Ende Foundation. Disclosure: Dr. Chen has nothing to disclose. Dr. Ende has nothing to disclose. Dr. Souayah has received personal compensation for activities with Walgreens as a consultant. Dr. Souayah has received research support from Talecris.

Pure Motor Chronic Inflammatory Demyelinating Polyneuropathy: Relationship to Multifocal Motor Neuropathy with Conduction Block (P06.137)

Objective: To report two cases of pure motor chronic inflammatory demyelinating polyneuropathy (CIDP), response to therapy, and possible relationship to multifocal motor neuropathy with conduction block (MMN). Background Motor CIDP is a rare variant of classic CIDP that is not well understood in regard to both its pathogenesis and appropriate treatment. The few studies that have been published suggest that unlike classic CIDP, motor CIDP does not respond well to corticosteroids. Design/Methods: Two motor CIDP patients are presented, one of whom has high titers to anti-GM1 antibodies. Results: Patient 1 is a 48 year old woman with a history of CIDP who developed worsening of her strength and diffuse wasting and fasciculations concerning for motor neuron disease. She was found to have an elevated titer of anti-GM1 antibodies of 1:102,400 and a pure motor demyelinating neuropathy with secondary axonal degeneration by electrodiagnosis. The patient failed to respond to weekly IVIG therapy and then worsened with corticosteroids, becoming bed-bound and requiring non-invasive ventilation. Despite weekly rituximab infusions, she continued to declined and was started on monthly plasma exchange and intravenous cyclophosphamide. She can now walk and her anti-GM1 antibody titer has fallen to 1:12,800. Patient 2 is a 56 year old man who presented with a three month history of fasciculations, progressive wasting, and diffuse weakness requiring a wheelchair after failing to respond to single courses of both IVIG and plasma exchange. His electrodiagnostic testing revealed findings similar to the first patient. He was restarted on weekly IVIG and, after 12 courses, finally recovered his ability to walk. Conclusions: Motor CIDP may be more resistant to treatment than classic CIDP. High titers of anti-GM1 antibodies and paradoxical worsening with corticosteroids in some patients could also support a distinct pathogenesis more similar to MMN. Abundant fasciculations seen in this disorder may mistakenly suggest motor neuron disease. Disclosure: Dr. Thyerlei has nothing to disclose. Dr. Weiss has received personal compensation for activities with Walgreens, CSL Behring and Talecris Biotherapeutics as a consultant and/or speaker.

A Randomised, Double-Blinded, Placebo Controlled Trial of the Effect of Subcutaneous Immunoglobulin on Muscular Performance in Chronic Inflammatory Demyelinating Polyneuropathy (P06.130)

Objective: We hypothesised that the effect of subcutaneous infusion of immunoglobulins(SCIG) on muscular performance in chronic inflammatory demyelinating polyneuropathy(CIDP) is superior to that of placebo and equals the therapeutic effect of intravenous infusion(IVIG). Background Subcutaneous treatment with large amounts of immunoglobulins in multifocal motor neuropathy is feasible, safe and effective. In CIDP case reports indicate its therapeutic usefullness as well. Design/Methods: Subjects in IVIG maintenace therapy full-filling the EFNS/PNS criteria for CIDP were considered for participation. Exclusion criteria were pregnancy, malignancies, dementia, severe medical disorders and psychiatric disturbances. Thirty CIDP patients(n,30) characterized as IVIG-responders by their treating physicians were included in the study.Participants were randomised to receive either subcutaneous IgG at a concentration of 1.6g/10cc or subcutaneous saline in a double-blinded fashion. Infusions were given twice or thrice weekly for 12 weeks at home. The amount of immunoglobulin corresponded to the clinically predetermined dose. The first subcutaneous infusion was delivered two weeks after the last IVIG treatment. Participants were evaluated at four time intervals: - 2 wks, 0, 10 wks, 12 wks. Strength was determined at isokinetic dynamometry from four predetermined and weakened muscle groups. Also, an Overall Disability Sum Score (ODSS), a 40 meter walking test, a nine hole peg test, a Neurological Impairment Score (NIS), a Medical Research Council (MRC) score and a grip strength test were included. The primary end-point is the change of strength at isokinetic dynamometry in the two study groups. Secondary end-points are the treatment response of SCIG vs IVIG and the variation of the treatment response during SCIG vs IVIG. Results: The study ran during the period april 2010 to october 2011. Data will be presented. Conclusions: To be presented. Supported by: Aarhus University Hospital. A research grant from Baxter. Disclosure: Dr. Jakobsen has received research support from Baxter Medical AB. Dr. Markvardsen has nothing to disclose. Dr. Harbo has nothing to disclose. Dr. Sindrup has received personal compensation for activities with Grunenthal, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly & Company, and Pfizer Inc. Dr. Andersen has nothing to disclose. Dr. Christiansen has nothing to disclose. Dr. Olsen has nothing to disclose. Dr. Lassen has nothing to disclose.

Single‐nucleotide polymorphism of transient axonal glycoprotein‐1 and its correlation with clinical features and prognosis in chronic inflammatory demyelinating polyneuropathy

The single-nucleotide polymorphism (SNP) rs2275697 in the transient axonal glycoprotein-1 (TAG-1) gene was reported to be associated with responsiveness to intravenous immunoglobulin (IVIG) treatment in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). However, it is not known if this SNP is associated with long-term prognosis. We examined the case records of 32 Chinese CIDP patients. The overall response rate to IVIG, prednisolone, or plasmapheresis was 83%. After 5.4 years, 57% of patients were on maintenance immunotherapy. Patients with higher modified Rankin score and more prolonged distal motor latencies in the upper limbs on presentation had a higher risk (odds ratio [OR] 3.86, 95% confidence interval [CI] 1.23-12.11 and OR 1.04, 95% CI 1.01-1.07, respectively) of being on maintenance immunotherapy. Blood samples from 24 patients and 147 controls were examined for their genotypes of four non-synonymous SNPs (rs41264871, rs36074532, rs5611135, and rs2275697) in the coding region of TAG-1. The G allelic frequency of rs2275697 was similar between CIDP patients and controls (56% and 50%, respectively) and was not associated with treatment responsiveness, treatment dependence, disability, or mortality.

Nodal proteins are target antigens in Guillain‐Barré syndrome

Neurofascin-186 (NF186), neuronal cell adhesion molecule (NrCAM), and gliomedin are adhesion molecules playing a central role in the formation of nodes of Ranvier. In Guillain-Barré syndrome (GBS), immune attack toward the nodes may participate in the disabilities. Autoantibodies to NF186 and gliomedin have been detected in a rat model of GBS. Here, we investigated the prevalence of antibodies against nodal adhesion molecules in patients with GBS or chronic inflammatory demyelinating polyneuropathy (CIDP). Sera from 100 GBS patients, 50 CIDP patients, 80 disease controls, and 50 healthy controls were tested for their ability to bind the nodes of Ranvier. To characterize the antigens, we performed cell binding assays against NF186, gliomedin, contactin, and NrCAM. We found that 43% of patients with GBS and 30% of patients with CIDP showed IgG fixation at nodes or paranodes. In eight patients with GBS or CIDP, we identified that IgG antibodies recognized the native extracellular domain of NF186, gliomedin, or contactin. Also, 29 patients showed IgM against nodal adhesion molecules. However, we did not detect IgM fixation at nodes or paranodes. Antibodies to gliomedin or NF186 were mostly detected in demyelinating and axonal GBS, respectively. The adsorption of the antibodies to their soluble antigens abolished IgG deposition at nodes and paranodes in nerves, indicating these were specific to NF186, gliomedin, and contactin. In conclusion, gliomedin, NF186, and contactin are novel target antigens in GBS. At nodes, additional epitopes are also the targets of IgG. These results suggest that antibody attack against nodal antigens participates in the etiology of GBS.

Different neurological and physiological profiles in POEMS syndrome and chronic inflammatory demyelinating polyneuropathy

BackgroundPOEMS (polyneuropathy, organomegaly, endocrinopathy, M protein and skin changes) syndrome, a rare cause of demyelinating neuropathy associated with multiorgan involvement, has been increasingly recognised. Polyneuropathy is often an initial manifestation...

INVITED EDITORIAL COMMENT

<h3>Background</h3> Myositis-specific autoantibodies (MSA) are increasingly recognized as important diagnostic and prognostic markers in idiopathic inflammatory myopathies (IIM) (polymyositis, dermatomyositis, sporadic inclusion body myositis and necrotizing autoimmune myositis). The prevalence of these MSAs in other systemic autoimmune rheumatic diseases and neuromuscular diseases is unclear. <h3>Objectives</h3> To compare positivity of MSA in a cohort of IIM patients to positivity in healthy controls and different systemic autoimmune rheumatic diseases (SARD) or chronic inflammatory demyelinating polyneuropathy (CIDP). <h3>Methods</h3> A line immunoassay (Myositis 12 IgG DOT for BlueDiver) for IgG autoantibodies against Jo-1, PL-7, PL-12, EJ, SRP, Mi-2, MDA-5, TIF1-γ, HMGCR, SSA/Ro52kD, SAE1/2 and NXP-2 antigens was performed in patients with IIM (n=146), healthy controls (blood donors, n=40) and disease controls (n=200). The disease control group consisted of patients with other SARD (rheumatoid arthritis, RA; systemic sclerosis, Ssc; Sjögren9s syndrome, SjS; and systemic lupus erythematosus, SLE) (n=40 for each disease group) and CIDP (n=40). A result &gt;10 arbitrary units was considered significantly positive. <h3>Results</h3> 50% of 146 patients with IIM tested positive for an MSA (table 1), compared to 3,5% of 200 disease controls (table 1). 1 SSc patient was positive for Jo-1, 1 CIDP patient was positive for PL12, 2 SSc patients were positive for TIF1-gamma, 2 patients (1 SSc and 1 SjS patient) were positive for SAE1/2, and 1 SjS patient was positive for NXP2. The prevalence of SAE1/2 and TIF1-gamma positivity was similar in the IIM and disease control group. No healthy control had a significantly positive MSA. <h3>Conclusions</h3> MSA positivity in patients with a clinical non-IIM diagnosis (other SARD or CIDP) is infrequent compared to positivity in the IIM group. For TIF1-gamma and SAE1/2 assay performance may need to be optimized. The distribution of subtypes of MSA in this IIM cohort is consistent with data of previous studies.¹ <h3>References</h3> Allenbach Y, Benveniste O. Diagnostic Utility of Autoantibodies in Inflammatory Muscle Diseases. J Neuromuscul Dis. 2015; 2:13–25. <h3>Disclosure of Interest</h3> None declared

New Treatments for Chronic Inflammatory Demyelinating Polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common treatable chronic neuropathy in the western world. There are three treatment options currently available for CIDP: intravenous immunoglobulin, plasma exchange or corticosteroids. Despite the efficacy of these therapies CIDP patients are often left with permanent neurological deficits, have a poor clinical prognosis or in some cases do not respond to treatment. Furthermore, high cost and restricted availability make them unfeasible in some treatment centres, especially in the developing world. Recent advances in the understanding of the underlying pathogenic mechanisms in CIDP have brought a number of novel agents into consideration for use in CIDP. Many of these novel therapies have been used in similar autoimmune disorders and target immunopathogenic pathways common to CIDP. Here we review a number of these novel therapies and their applicability to CIDP.

A European multicentre reappraisal of distal compound muscle action potential duration in chronic inflammatory demyelinating polyneuropathy

The electrodiagnostic value of distal compound muscle action potential duration (DCMAPD) has been studied rarely in chronic inflammatory demyelinating polyneuropathy (CIDP). Cut-offs proposed have not been widely evaluated. The influence of low-cut EMG filter settings ≤ 10 Hz as used in Europe is uncertain. We retrospectively reviewed records of 110 patients with typical, treatment-responsive CIDP, from Leicester, U.K., Paris and Angers, France. All fulfilled revised European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) clinical and electrodiagnostic criteria for typical CIDP (2010), before consideration of DCMAPD prolongation. Results were compared with those of 110 controls with chronic sensory/sensory-motor axonal neuropathy. We constructed receiver operating characteristic (ROC) curves for each nerve and derived cut-offs for DCMAPD prolongation, offering specificity of ≥ 98% vs. controls. DCMAPD was significantly greater in all nerves for CIDP patients, compared with controls (P < 0.001). ROC curves allowed derivation of cut-offs of sensitivities ranging from 27.1% (ulnar nerve) to 60% (tibial nerve). Using these cut-offs to define DCMAPD prolongation in any studied motor nerve offered a sensitivity of 69.1% for CIDP and specificity of 97.3% vs. controls. Cut-offs for DCMAPD are dependent on EMG filter settings. DCMAPD prolongation in any motor nerve, using our derived cut-offs, represents a sensitive and specific marker of CIDP in patients studied with EMG equipment with low-cut filter settings ≤ 10 Hz. Appropriate use of this parameter appears an essential criterion to consider in assessing suspected CIDP, which may be helpful in limiting extensiveness and duration of electrophysiological testing, thereby reducing patient discomfort.

Prolongation of the tibialis anterior CMAP duration in chronic inflammatory demyelinating polyneuropathy

Objective To assess the duration of the distal compound muscle action potential (dCMAP) recording from the tibialis anterior (TA) as a supportive electrodiagnostic feature in chronic inflammatory demyelinating polyneuropathy (CIDP). Methods We performed peroneal motor conduction studies with recording from the TA in 35 CIDP patients, 30 normal controls, and 21 disease controls. The normal cut-off for the TA dCMAP duration was determined to be 14 ms. Results Prolonged TA dCMAP durations were detected in 34% of CIDP patients (12/35) and in 33% (2/6) of patients in whom only one demyelinating lesion was identified by conventional motor conduction studies. Prolonged TA dCMAP durations were present in 28% (5/18) of patients with normal duration dCMAPs recorded from the abductor hallucis (AH) and in 42% (5/12) of patients with normal duration dCMAPs recorded from the extensor digitorum brevis (EDB). In patients with AH or EDB dCMAP amplitudes <1 mV, TA dCMAP durations were prolonged in 28% and 23% of patients, respectively. Conclusions Determination of TA dCMAP duration appears to be useful for detecting demyelination in CIDP, especially when there is significant coexisting axon loss. Significance In patients with potential CIDP and limited electrodiagnostic abnormalities by routine studies, the finding of additional demyelinating findings, such as increased TA dCMAP duration, could allow for improved diagnostic sensitivity.

Modulatory Effects on Axonal Function After Intravenous Immunoglobulin Therapy in Chronic Inflammatory Demyelinating Polyneuropathy

To investigate the immediate and longitudinal mechanisms of action of intravenous immunoglobulin (IVIg) on axonal function in chronic inflammatory demyelinating polyneuropathy (CIDP). Prospective single-center study. Hospitals and outpatient clinics. Clinical and functional assessment, nerve conduction studies, and 526 motor excitability studies were undertaken in 27 patients, matched before and immediately after infusion and followed up longitudinally. Axonal excitability variables were measured before and immediately after infusion and compared with matched studies and findings in healthy controls. Immediately after infusion, patients demonstrated decreased threshold, with significant reduction in strength-duration time constant (P=.003), reduction in accommodation to depolarization (P=.04), and reduced threshold change during hyperpolarization (P=.003), accompanied by significant decreases in superexcitability (P=.03) and subexcitability (P=.02). In contrast, changes were absent in disease controls, confirming a specific IVIg action in CIDP patients. Longitudinally, changes correlated with clinical improvement (mean [SE] increase in the Medical Research Council sum score, 2.7 [0.7]; P=.005). Increased compound muscle action potential amplitude was associated with reduction in terminal latency (correlation coefficient, -0.65; P=.02). In addition, these changes translated into improvement in functional assessment with the adjusted Inflammatory Neuropathy Cause and Treatment score, which demonstrated a significant correlation with nerve excitability variables longitudinally (P=.01). Findings from the present series establish a modulatory effect of IVIg on axonal function in CIDP patients, suggesting that IVIg stabilizes axonal membrane potential and promotes axonal recovery.

Fas‐mediated T‐cell apoptosis in chronic inflammatory demyelinating polyneuropathy

The Fas receptor is expressed by activated lymphocytes and is involved in switching off the immune response. Defective Fas function causes the autoimmune lymphoproliferative syndrome, but is also involved in common autoimmune disorders. Fas-mediated T-cell apoptosis is impaired in chronic inflammatory demyelinating polyneuropathy (CIDP), but not in Guillain-Barré syndrome (GBS). The defect seems to have a genetic component and involve the extrinsic apoptotic pathway mediated by caspase-8. The analysis of clinical features shows that Fas function is lower in CIDP patients with a progressive course and axonal damage, suggesting that defective Fas function favors not only CIDP development but also its aggressive evolution. Moreover, testing T-cell Fas function in patients with acute-onset demyelinating polyneuropathy can help in early discrimination between GBS and acute-onset CIDP.

Differential gene expression in nerve biopsies of inflammatory neuropathies

DNA microarray analysis is a powerful tool for simultaneous analysis and comparison of gene products expressed in normal and diseased tissues. We used this technique to identify differentially expressed genes (DEGs) in nerve biopsy samples of chronic inflammatory demyelinating polyneuropathy (CIDP) and vasculitic neuropathy (VAS) patients. We found novel previously uncharacterized genes of relevance to CIDP or VAS pathogenesis. Of particular interest in CIDP were tachykinin precursor 1, which may be involved in pain mediation, stearoyl-co-enzyme A (CoA) desaturase, which may be a marker for remyelination, HLA-DQB1, CD69, an early T-cell activation gene, MSR1, a macrophage scavenger receptor, and PDZ and LIM domain 5 (PDLIM5), a factor regulating nuclear factor (NF)-kappa B activity. Genes upregulated in VAS included IGLJ3, IGHG3, IGKC, and IGL, which all function in B-cell selection or antigen recognition of B cells. Other upregulated genes included chemokines, such as CXCL9 and CCR2, as well as CPA3, a mast cell carboxypeptidase. Allograft inflammatory factor-1 (AIF-1), a modulator of immune response was upregulated both in CIDP and VAS. Microarray-based analysis of human sural nerve biopsies showed distinct gene expression patterns in CIDP and VAS. DEGs might provide clues to the pathogenesis of the diseases and be potential targets for therapeutics.

Polymorphism of transient axonal glycoprotein‐1 in chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is characterized by immune-mediated peripheral demyelination. Although corticosteroid, intravenous immunoglobulin (IVIg), and plasma exchange have been established as the most effective therapeutics, sub-populations of patients show little or no response to either of these therapies. We identified the clinical, electrophysiological, and genetic features related to IVIg responsiveness in CIDP by conducting a multi-center study. Muscle atrophy and decreased compound muscle action potential (CMAP) were pronounced in IVIg non-responders, that is, features suggesting axonal dysfunction in peripheral nerves indicated IVIg unresponsiveness in CIDP. We then performed an association analysis using single nucleotide polymorphisms (SNPs) and haplotype studies between the IVIg responders and non-responders. We assessed SNPs of candidate genes that are particularly related to the function of Ranvier's node, paranode, or juxtaparanode. Two separate SNPs, corresponding to transient axonal glycoprotein-1 (TAG-1) and C-type lectin domain family 10, member A (CLEC10A), showed significant differences between responders and non-responders. Haplotype analysis of a series of expanded SNPs, from TAG-1 or CLEC10A, showed that only TAG-1 included a significant haplotype within one linkage disequilibrium block that accommodates IVIg responsiveness. Diplotype analysis of TAG-1 also supported this observation. In conclusion, SNPs in TAG-1, which is a key molecule for axon-Schwann cell interactions and is distributed at the juxtaparanode, are related to the IVIg responsiveness of CIDP patients.

Symptoms of activity‐induced weakness in peripheral nervous system disorders

Activity-induced weakness was reported in multifocal motor neuropathy (MMN) and chronic inflammatory demyelinating polyneuropathy (CIDP). This was attributed to activity-dependent conduction block (CB) arising in demyelinated axons. It is not known if activity-induced weakness is common, nor if it is specific for MMN and CIDP. We, therefore, carried out an investigation by questionnaire in 64 MMN patients, 52 CIDP patients, 48 progressive spinal muscular atrophy (PSMA) patients, and 30 normal subjects. Subjects were asked if they experienced an increase in weakness when performing 10 common tasks. The percentage of tasks causing activity-induced weakness was higher in the patient groups than in the normal subjects (p < 0.001). The risk of activity-induced weakness exceeding that in normal subjects was sixfold higher for each patient group when adjusted for sex, age, and a fatigue score. With further adjustment for scores of weakness and axon loss, no significant differences were found between the patient groups. In conclusion, activity-induced weakness is frequently reported in MMN and CIDP. It is, however, not specific for these neuropathies as PSMA patients reported it to the same extent.

Establishing common clinical research standards for CIDP

Various clinical scores are available to assess the outcome of chronic inflammatory demyelinating polyneuropathy (CIDP), but these existing scales have some major limitations. A novel, simple scoring system—the CIDP disease activity status—incorporates the concept of disease activity as a feature that informs the long-term outcome in CIDP patients.

Distinct cytokine patterns associated with different forms of chronic dysimmune neuropathy

To better understand the presumed immune system dysregulation of chronic dysimmune neuropathy (CDN) patients, we designed a study to evaluate the levels of pro- and anti-inflammatory cytokines in the most common forms of CDN: chronic inflammatory demyelinating polyneuropathy (CIDP), and anti-myelin-associated glycoprotein (MAG)-related polyneuropathy (MAGnp). Sixteen patients fulfilled diagnostic criteria for CIDP, 14 were diagnosed with MAGnp, and 36 were classified as exhibiting "chronic idiopathic polyneuropathy" (CIP). Cytokine production in mitogen-stimulated peripheral blood mononuclear cells (PBMCs) was analyzed by flow cytometry. CIDP and MAGnp patients were compared with CIP patients, those with monoclonal gammopathy without polyneuropathy (MGUS), and healthy controls (HC). We observed an increase in pro-inflammatory cytokines in the CIDP group, whereas interleukin-10 (IL-10) was augmented in the MAGnp patients. These distinctive immune alterations may represent a biological tool in differential diagnosis and future therapeutic approaches.

Activity-dependent conduction block in chronic inflammatory demyelinating polyneuropathy

Previous studies suggested that activity-dependent conduction block (CB) contributes to weakness in chronic inflammatory demyelinating polyneuropathy (CIDP). These studies, however, investigated only one nerve segment per patient, employed cervical magnetic stimulation which may be submaximal, included nerves with extremely low compound muscle action potentials (CMAPs) which precludes assessment of CB, and lacked predefined criteria for activity-dependent CB. Obtaining more robust evidence for activity-dependent CB is important because it may be treated pharmacologically. We investigated 22 nerve segments in each of 18 CIDP patients, employed supramaximal electrical stimulation, excluded nerves with markedly reduced CMAPs, and adopted criteria for activity-dependent CB. Each nerve was tested before and immediately after 60 s of maximal voluntary contraction (MVC) of the relevant muscle. Per nerve segment we calculated segmental area ratio: (area proximal CMAP)/(area distal CMAP). Per nerve we calculated total area ratio: (area CMAP evoked at Erb's point)/(area most distally evoked CMAP). MVC induced no change in mean area ratios and no activity-dependent CB according to our criteria, except for one segment. MVC induced increases in distal and proximal CMAP area and duration. In segments with demyelinative slowing, MVC induced an increase in CMAP duration prolongation. Thus, in CIDP, muscle activity induces virtually no CB, but it may increase temporal dispersion of nerve action potentials.

POI12 Electrophysiological sensory demyelination in typical chronic inflammatory demyelinating polyneuropathy

BackgroundElectrophysiological demyelination of sensory nerves is not routinely assessed in the evaluation of suspected chronic inflammatory demyelinating polyneuropathy (CIDP). Its usefulness is unknown.MethodsWe compared in 19 patients with typical chronic...