Electrodiagnostic criteria for acute and chronic inflammatory demyelinating polyradiculoneuropathy

Neuropathy 10-15 years after Roux-en-Y gastric bypass for severe obesity: A community-controlled nerve conduction study

Objective

We searched for long-term peripheral nerve complications 10-15 years after Roux-en-Y gastric bypass surgery (RYGB), using a comprehensive nerve conduction study (NCS) protocol.

Methods

Patients (n = 175, mean age 52.0, BMI 35.2) and 86 community-controls (mean age 56.8, BMI 27.2) had NCS of one upper and lower limb. New abnormality scores from 27 polyneuropathy-relevant (PNP27s) and four carpal tunnel syndrome-relevant NCS-measures (CTS4s) were compared between groups with non-parametric statistics. Estimated prevalences were compared by 95 % confidence limits. The clinical neurophysiologist's diagnosis was retrieved from hospital records (PNP-ncs, CTS-ncs, other).

Results

Abnormality score did not differ between RYGB and control groups (PNP27s: 1.9 vs 1.7, CTS4s: 0.7 vs 0.6, p > 0.29). BMI correlated weakly with CTS4s in patients (rho = 0.19, p = 0.01), and less with PNP27s (rho = 0.12, p = 0.12). Polyneuropathy (PNP-ncs) prevalence was 12 % in patients and 8 % in controls. CTS-ncs prevalence was 21 % in patients and 10 % in controls (p = 0.04).

Conclusions

NCS-based abnormality scores did not differ between patients 10-15 years after RYGB and community-recruited controls, neither for PNP nor CTS.

Significance

Long-term polyneuropathic complications from RYGB have probably been avoided by modern treatment guidelines. NCS-diagnosed CTS is common in overweight RYGB patients. RYGB-patients with significant neuropathic symptoms need clinical evaluation.

A recent surge of nitrous oxide misuse around London which merits a public health warning

BACKGROUND

Use of nitrous oxide (N2O) gas for recreational purposes by young people is increasingly recognized as a public health hazard in the UK.

METHODS

We looked at the hospital records of patients admitted over the last 4 years to a single neurological centre in Essex to determine the demographics, presentation, and management of patients presenting with symptoms of N2O toxicity from its recreational use.

RESULTS

Of the 17 patients (mean age = 22.9 ± 3 years) admitted between September 2018 and October 2022, 70% were admitted between January and October 2022. All patients reported limb paraesthesiae and 16/17 reported (95%) imbalance; 11/17 (65%) showed objective limb weakness. Serum B12 concentration was low in 9/17 (53%). Plasma methylmalonic acid (n = 7) and homocysteine (n = 8) levels were elevated in all patients tested. Spinal cord Magnetic Resonance Imaging (MRI) imaging was abnormal in 10/17 (59%) patients. Nerve conduction studies were abnormal in 10/13 (77%) patients, with evidence of a symmetric, length-dependent, large fibre neuropathy.

CONCLUSIONS

There has been a recent surge of cases with neurological complications of recreational N2O abuse in the UK, with a relatively greater rate in 2022. Greater awareness of this condition amongst clinicians and health regulators is urgently required to prevent harm from N2O misuse in young people.

How to distinguish Guillain-Barré syndrome from nitrous oxide-induced neuropathy: A 2-year, multicentric, retrospective study

BACKGROUND

Recreational use of nitrous oxide (N2 O) has dramatically increased in recent years, resulting in numerous cases of acute sensorimotor tetraparesis secondary to nitrous oxide-induced neuropathy (N2 On). Challenging clinical features can mimic Guillain-Barré syndrome (GBS), the main differential diagnosis upon admission. The most sensitive biomarkers for distinguishing between these two conditions remain to be determined.

METHODS

Fifty-eight N2 On patients from three referral centers were retrospectively included over a 2-year period and compared to GBS patients hospitalized during the same timeframe (47 patients). Collected demographic, clinical, biological, and electrophysiological data were compared between the two groups.

RESULTS

The typical N2 On clinical pattern included distal sensorimotor deficit in lower limbs with absent reflexes, proprioceptive ataxia, and no cranial involvement (56.7% of our cohort). Misleading GBS-like presentations were found in 14 N2 On patients (24.1%), and 13 patients (22.4%) did not report N2 O use during initial interview. Only half the N2 On patients presented with reduced vitamin B12 serum levels upon admission. A slightly increased cut-off (<200 pmol/L) demonstrated 85.1% sensitivity and 84.5% specificity in distinguishing N2 On from GBS. Only 6.9% of N2 On patients met the criteria for primary demyelination (p < 0.01), with only one presenting conduction blocks. A diagnostic algorithm combining these two biomarkers successfully classified all GBS-like N2 On patients.

CONCLUSIONS

Vitamin B12 serum level < 200 pmol/L cut-off and conduction blocks in initial electrophysiological study are the two most sensitive biomarkers for rapidly distinguishing N2 On from GBS patients. These two parameters are particularly useful in clinically atypical N2 On with GBS-like presentation.

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP): Overview, Treatment, and a Case Study

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an uncommon immune-mediated neuropathy with an often unknown etiology. Patients typically present with gradual muscle weakness, sensory loss, and reduced deep tendon reflexes. Diagnostic challenges persist due to the absence of specific lab findings and definitive criteria. Treatment commonly involves glucocorticoids, IVIG, or plasma exchange, with varied long-term outcomes. We aim to elucidate the diagnostic complexities and treatment modalities associated with chronic CIDP through a comprehensive review of a patient's clinical presentation, diagnostic work-up, and therapeutic interventions. A 70-year-old female with a complex medical history, including dermatomyositis and IgG subclass deficiency, presented with progressive lower extremity weakness and numbness. Initial workup including MRI and CT scans were inconclusive. She was diagnosed with CIDP based on electromyography (EMG)/nerve conduction studies and cerebrospinal fluid (CSF) analysis. Plasma exchange (PLEX) treatment was initiated but led to multifocal cerebral infarcts, complicating her course. Subsequent rounds of PLEX alongside dual antiplatelet therapy showed no adverse neurological events and yielded minimal to moderate improvement in her mobility. The patient was discharged to an inpatient rehabilitation center for continued care. Elevated WBCs and other abnormal lab results were monitored throughout, underscoring the need for a multidisciplinary approach in complex cases like this one. Our comprehensive overview of CIDP and its diagnostic and treatment complexities underscores the challenges clinicians face in both accurate diagnosis and effective management. The multifaceted approach - spanning history-taking, electrodiagnostic studies, and advanced imaging - highlights the necessity for a nuanced, evidence-based practice. The variability in treatment outcomes emphasizes the need for personalized medicine and continuous research to optimize therapeutic strategies. Given the inconclusive nature of some diagnostic tools and the variable treatment responses, there remains a clear need for ongoing study and long-term follow-up to further refine our understanding and management of CIDP.

Autonomic nervous system involvement in chronic inflammatory demyelinating polyradiculoneuropathy: a literature review

BACKGROUND AND AIMS

Although dysautonomia is a well-recognized complication of acute demyelinating polyradiculoneuropathy, it is rarely reported and evaluated in chronic demyelinating neuropathies. The purpose of this review is to search and synthesize the current literature on the prevalence and type of autonomic dysfunction (AD) in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

METHODS

PubMed and Web of Science were searched for studies reporting AD in CIDP.

RESULTS

Twelve studies, including 346 patients with CIDP, were found eligible for the review. Seven studies used autonomic tests only as an additional component of the comprehensive clinical evaluation, and found that dysautonomia in CIDP may indicate the presence of a comorbid disease (e.g., diabetes) and facilitate the differentiation of CIDP from other neuropathies (e.g., amyloid neuropathy). Five studies performed quantitative assessment of autonomic function in CIDP as a primary goal. Two studies have used the Composite Autonomic Severity Score (CASS) to assess severity and distribution of dysautonomia. The reported prevalence of dysautonomia in CIDP during quantitative assessment of autonomic function ranged from 25 to 89%, depending on the battery of tests used, with CASS not exceeding 4 points. The abnormalities in autonomic tests indicated both sympathetic and parasympathetic dysfunction and did not correlate with the duration, severity and variant of CIDP.

CONCLUSIONS

Clinical or subclinical involvement of the ANS has been shown to be common and relatively mild in CIDP. The impact of autonomic impairment on disability and of its possible response to therapy in CIDP needs to be further investigated.

Emerging biomarkers to predict clinical outcomes in Guillain-Barré syndrome

INTRODUCTION

Guillain-Barré syndrome (GBS) is an immune-mediated poly(radiculo)neuropathy with a variable clinical outcome. Identifying patients who are at risk of suffering from long-term disabilities is a great challenge. Biomarkers are useful to confirm diagnosis, monitor disease progression, and predict outcome.

AREAS COVERED

The authors provide an overview of the diagnostic and prognostic biomarkers for GBS, which are useful for establishing early treatment strategies and follow-up care plans.

EXPERT OPINION

Detecting patients at risk of developing a severe outcome may improve management of disease progression and limit potential complications. Several clinical factors are associated with poor prognosis: higher age, presence of diarrhea within 4 weeks of symptom onset, rapid and severe weakness progression, dysautonomia, decreased vital capacity and facial, bulbar, and neck weakness. Biological, neurophysiological and imaging measures of unfavorable outcome include multiple anti-ganglioside antibodies elevation, increased serum and CSF neurofilaments light (NfL) and heavy chain, decreased NfL CSF/serum ratio, hypoalbuminemia, nerve conduction study with early signs of demyelination or axonal loss and enlargement of nerve cross-sectional area on ultrasound. Depicting prognostic biomarkers aims at predicting short-term mortality and need for cardio-pulmonary support, long-term patient functional outcome, guiding treatment decisions and monitoring therapeutic responses in future clinical trials.

On the path to evidence-based therapy in neuromuscular disorders

Neuromuscular disorders encompass a diverse group of acquired and genetic diseases characterized by loss of motor functionality. Although cure is the goal, many therapeutic strategies have been envisioned and are being studied in randomized clinical trials and entered clinical practice. As in all scientific endeavors, the successful clinical translation depends on the quality and translatability of preclinical findings and on the predictive value and feasibility of the clinical models. This chapter focuses on five exemplary diseases: childhood spinal muscular atrophy (SMA), Charcot-Marie-Tooth (CMT) disorders, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), acquired autoimmune myasthenia gravis (MG), and Duchenne muscular dystrophy (DMD), to illustrate the progress made on the path to evidenced-based therapy.

Tips in navigating the diagnostic complexities of chronic inflammatory demyelinating polyradiculoneuropathy

The 2021 guideline of the European Academy of Neurology/Peripheral Nerve Society on chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) includes important revisions to the previous 2010 guideline. This article highlights the new criteria and recommendations for the differential diagnosis of CIDP. In the revised guideline, the CIDP spectrum has been modified to include typical CIDP and four well-characterized CIDP variants, namely distal, multifocal/focal, motor and sensory CIDP, replacing the term 'atypical' CIDP. To improve the diagnosis of CIDP, the revised guideline attempts to improve the specificity of the diagnostic criteria for typical CIDP and the four CIDP variants. Specific clinical and electrodiagnostic (including both motor and sensory conduction) criteria are provided for typical CIDP and each of the CIDP variants. The levels of diagnostic certainty have been changed to CIDP and possible CIDP, with the removal of probable CIDP (due to the lack of difference in the accuracy of the electrodiagnostic criteria for probable CIDP) and definite CIDP (due to the lack of a gold standard for diagnosis). If the clinical and electrodiagnostic criteria allow only for a diagnosis of possible CIDP, cerebrospinal fluid analysis, nerve ultrasound, nerve magnetic resonance imaging, objective treatment response, and nerve biopsy can be used as supportive criteria to upgrade the diagnosis to CIDP. Although the revised guideline needs to be validated and its strengths and weaknesses assessed, using the guideline will likely improve the accuracy of diagnosis of CIDP and variants of CIDP, and aid in distinguishing CIDP from conditions with similar features.

Comparison of the diagnostic accuracy of the 2021 EAN/PNS and 2010 EFNS/PNS diagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy

OBJECTIVES

To compare the sensitivity and specificity of the 2021 European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) diagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with those of the 2010 European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS).

METHODS

Sensitivity and specificity of the two sets of criteria were evaluated in 330 patients with CIDP and 166 axonal peripheral neuropathy controls. Comparison of the utility of nerve conduction studies with different number of nerves examined and of the sensitivity and specificity of the two criteria in typical CIDP and its variants were assessed.

RESULTS

EFNS/PNS criteria had a sensitivity of 92% for possible CIDP and 85% for probable/definite CIDP, while the EAN/PNS criteria had a sensitivity of 83% for possible CIDP and 74% for CIDP. Using supportive criteria, the sensitivity of the EAN/PNS criteria for possible CIDP increased to 85% and that of CIDP to 77%, remaining lower than that of the EFNS/PNS criteria. Specificity of the EFNS/PNS criteria was 68% for possible CIDP and 84% for probable/definite CIDP, while the EAN/PNS criteria had a specificity of 88% for possible CIDP and 98% for CIDP. More extended studies increased the sensitivity of both sets of criteria by 4%-7% but reduced their specificity by 2%-3%. The EFNS/PNS criteria were more sensitive for the diagnosis of typical CIDP while the EAN/PNS criteria were more specific for the diagnosis of distal and sensory CIDP.

CONCLUSIONS

In our population, the EAN/PNS criteria were more specific but less sensitive than the EFNS/PNS criteria. With the EAN/PNS criteria, more extended nerve conduction studies are recommended to obtain an acceptable sensitivity while maintaining a high specificity.

Classical Complement Pathway Inhibition in a "Human-On-A-Chip" Model of Autoimmune Demyelinating Neuropathies

Chronic autoimmune demyelinating neuropathies are a group of rare neuromuscular disorders with complex, poorly characterized etiology. Here we describe a phenotypic, human-on-a-chip (HoaC) electrical conduction model of two rare autoimmune demyelinating neuropathies, chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN), and explore the efficacy of TNT005, a monoclonal antibody inhibitor of the classical complement pathway. Patient sera was shown to contain anti-GM1 IgM and IgG antibodies capable of binding to human primary Schwann cells and induced pluripotent stem cell derived motoneurons. Patient autoantibody binding was sufficient to activate the classical complement pathway resulting in detection of C3b and C5b-9 deposits. A HoaC model, using a microelectrode array with directed axonal outgrowth over the electrodes treated with patient sera, exhibited reductions in motoneuron action potential frequency and conduction velocity. TNT005 rescued the serum-induced complement deposition and functional deficits while treatment with an isotype control antibody had no rescue effect. These data indicate that complement activation by CIDP and MMN patient serum is sufficient to mimic neurophysiological features of each disease and that complement inhibition with TNT005 was sufficient to rescue these pathological effects and provide efficacy data included in an investigational new drug application, demonstrating the model's translational potential.

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) in Diabetes Mellitus: A Diagnostic Dilemma

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a neurological disorder of the peripheral nerves which can lead to gradually increasing motor and sensory loss. It can be a difficult entity to diagnose, particularly in elderly patients with a history of Diabetes Mellitus due to their overlapping neuropathic syndromes. Reported is a case of CIDP in an elderly female who manifested multiple sensory, motor, and autonomic complaints. A compilation of clinical features, neuroimaging, lumbar puncture, electromyography, nerve conduction studies, and nerve biopsy were used to reach the diagnosis. Highlighted is a clinical approach to identifying CIDP that can cause neuropathy in the setting of other potential confounding disorders namely Diabetes Mellitus. 

Clinical Course and Diagnostic Findings of Biopsy Controlled Presumed Immune-Mediated Polyneuropathy in 70 European Cats

There is a paucity of information on the clinical course and outcome of young cats with polyneuropathy. The aim of the study was to describe the clinical features, diagnostic investigations, and outcome of a large cohort of cats with inflammatory polyneuropathy from several European countries. Seventy cats with inflammatory infiltrates in intramuscular nerves and/or peripheral nerve biopsies were retrospectively included. Information from medical records and follow up were acquired via questionnaires filled by veterinary neurologists who had submitted muscle and nerve biopsies (2011-2019). Median age at onset was 10 months (range: 4-120 months). The most common breed was British short hair (25.7%), followed by Domestic short hair (24.3%), Bengal cat (11.4%), Maine Coon (8.6%) and Persian cat (5.7%), and 14 other breeds. Male cats were predominantly affected (64.3%). Clinical signs were weakness (98.6%) and tetraparesis (75.7%) in association with decreased withdrawal reflexes (83.6%) and, less commonly, cranial nerve signs (17.1%), spinal pain/hyperesthesia (12.9%), and micturition/defecation problems (14.3%). Onset was sudden (30.1%) or insidious (69.1%), and an initial progressive phase was reported in 74.3%. Characteristic findings on electrodiagnostic examination were presence of generalized spontaneous electric muscle activity (89.6%), decreased motor nerve conduction velocity (52.3%), abnormal F-wave studies (72.4%), pattern of temporal dispersion (26.1%) and unremarkable sensory tests. The clinical course was mainly described as remittent (49.2%) or remittent-relapsing (34.9%), while stagnation, progressive course or waxing and waning were less frequently reported. Relapses were common and occurred in 35.7% of the cats' population. An overall favorable outcome was reported in 79.4% of patients. In conclusion, young age at the time of diagnosis and sudden onset of clinical signs were significantly associated with recovery (p < 0.05). Clinical and electrodiagnostic features and the remittent-relapsing clinical course resembles juvenile chronic inflammatory demyelinating polyneuropathy (CIDP), as seen in human (children/adolescents), in many aspects.

Does specificity of electrodiagnostic test referrals predict for test outcome in children?

INTRODUCTION/AIMS

Electrodiagnostic testing (EDX) is important in evaluation of pediatric neuromuscular disease. Non-specific referrals have emerged as a leading reason for EDX in recent years. We examine whether referral-specificity is predictive of test outcomes in children.

METHODS

EDX referrals and outcomes were audited over a 7-year period from 2013 to 2020 at CHI-Crumlin. Pre-test details were coded and compared to EDX outcomes using multinomial logistic regression.

RESULTS

EDX studies were performed in 702 children (median age 10.2 yrs). In 36% of patients, EDX-referrals did not specify any pre-test diagnosis. Mononeuropathy (24%) and polyneuropathy (15%) were the leading pre-specified diagnoses as well as the most common test outcomes. Neurology and orthopedics/plastic surgery contributed the majority of referrals. Metabolic medicine and hematology/oncology were most likely to pre-specify a working diagnosis and were the specialties with both the highest proportion of abnormal outcomes and referral accuracy. EDX abnormality was present in 42% of patients and was predicted by specificity of referral and the absence of pain as a leading symptom. The accuracy of specified pre-test diagnoses was highest for suspected anterior horn cell disorders (67%). Accuracy of referrals, as well as abnormal test outcomes, were negatively predicted by the presence of pain as a leading symptom.

DISCUSSION

EDX is informative in children but the likelihood of abnormal test-outcomes is diminished when a pre-specified working diagnosis is lacking or when the primary reason for referral is pain. This article is protected by copyright. All rights reserved.

Electrophysiology of Guillain-Barré syndrome in Bangladesh: A prospective study of 312 patients

•

Classification of neurophysiologic subtypes of Guillain-Barré syndrome largely depended on the applied criteria.

•

Anti-GM1 antibodies were not exclusively associated with axonal Guillain-Barré syndrome.

•

Conduction block was not exclusively associated with demyelinating Guillain-Barré syndrome.

Objective

To describe the electrophysiological features in relation to clinical and serological findings of Guillain-Barré syndrome (GBS) in the national neuroscience hospital in Bangladesh. This is one of the few studies that investigated GBS patients using standardized electrophysiology in low-income countries.

Methods

In a prospective and observational study, we investigated 312 GBS patients by standardized clinical, serological and electrophysiological methods. Unilateral motor and sensory nerve conduction studies (NCS) were performed within two weeks of onset of weakness. Follow up NCS were performed in 189 patients and classified according to eight sets of established GBS criteria. Serology included assessment of anti-GM1 antibodies and anti-campylobacter jejuni lipo-oligosaccharide (LOS) antibodies.

Results

Depending on the criteria used, 44–59% patients had axonal GBS with anti-GM1 antibodies being present in 55–58% and 9–42% patients had demyelinating GBS with anti-GM1 antibodies being present in 7–35%. Conduction block (CB) with demyelinative slowing in the same nerve segment was found in 24% (74/312) patients, and CB without demyelinative slowing in the same nerve segment was found in 18% (56/312) patients, of whom anti-GM1 antibodies were found in 27% and 57% patients respectively. Follow-up NCS showed a change in GBS classification in 11–26% of patients, mainly from demyelinating to axonal GBS.

Conclusions

The predominant subtype of GBS in Bangladesh is axonal but demyelinating GBS also occurs with classification being strongly dependent on the applied criteria.

Significance

The present study demonstrates the importance of reaching international agreement on GBS criteria that should be based on the best evidence.

The red flags of ulnar neuropathy in leprosy

The diagnosis of pure neural leprosy is more challenging because patients share characteristics with other common pathologies, such as ulnar compression, which should be taken into consideration for differential diagnosis. In this study, we identify ulnar nerve conduction characteristics to aid in the differential diagnosis of ulnar neuropathy (UN) in leprosy and that of non-leprosy etiology. In addition, we include putative markers to better understand the inflammatory process that may occur in the nerve. Data were extracted from a database of people affected by leprosy (leprosy group) diagnosed with UN at leprosy diagnosis. A non-leprosy group of patients diagnosed with mechanical neuropathy (compressive, traumatic) was also included. Both groups were submitted to clinical, neurological, neurophysiological and immunological studies. Nerve enlargement and sensory impairment were significantly higher in leprosy patients than in patients with compressive UN. Bilateral impairment was significantly higher in the leprosy group than in the non-leprosy group. Leprosy reactions were associated to focal demyelinating lesions at the elbow and to temporal dispersion (TD). Clinical signs such as sensory impairment, nerve enlargement and bilateral ulnar nerve injury associated with eletrodiagnostic criteria such as demyelinating finds, specifically temporal dispersion, could be tools to help us decided on the best conduct in patients with elbow ulnar neuropathy and specifically decide if we should perform a nerve biopsy for diagnosis of pure neural leprosy.

Nitrous oxide-induced predominantly motor neuropathies: a follow-up study

OBJECTIVES

Recreational nitrous oxide (N₂O) abuse is increasingly popular among youth. We report a systematic clinical, electrophysiological and biological follow-up of patients with neuropathy caused by N₂O.

METHODS

We retrospectively report seven patients with neuropathy attributed to N₂O abuse and their comprehensive follow-up. Demographic, toxicological, clinical, biological and electrophysiological data were collected at first and second examination. Functional data were collected at the last evaluation.

RESULTS

Seven patients aged 18-30, consuming more than 140 gas-filled balloons (one balloon is filled with approximately 8 g of N₂O) per week for over a month, developed a severe, predominantly motor, length-dependent, progressive neuropathy over 3 to 6 weeks. Two-thirds presented associated signs of myelopathy. Distal lower limbs motor deficit and ataxia led to moderate disability. Spinal cord imaging was frequently normal. Nerve conduction studies disclosed an almost exclusively motor axonal neuropathy affecting the lower limbs with active denervation. Homocysteine plasma level was systematically elevated, whereas cobalamin plasma levels were normal in almost all patients. At short-term follow-up after intoxication discontinuation, ataxia and motor deficit only partially resolved despite vitamin B12 supplementation, while active denervation and homocysteinemia decreased. At last follow-up (median 9.2 months, IQR 7.5-10.75), mean ONLS was 2.0 (IQR 2.0-2.0).

DISCUSSION

Young patients, with induced N₂O motor neuropathy remain disabled after 5 to 14.5 months of gas withdrawal, despite vitamin B12 supplementation. A longer follow-up is needed to fully appraise the severity of these toxic neuropathies.

European Academy of Neurology/Peripheral Nerve Society guideline on diagnosis and treatment of chronic inflammatory demyelinating polyradiculoneuropathy: Report of a joint Task Force-Second revision

OBJECTIVE

To revise the 2010 consensus guideline on chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

METHODS

Seventeen disease experts, a patient representative, and two Cochrane methodologists constructed 12 Population/Intervention/Comparison/Outcome (PICO) questions regarding diagnosis and treatment to guide the literature search. Data were extracted and summarized in GRADE summary of findings (for treatment PICOs) or evidence tables (for diagnostic PICOs).

RESULTS

Statements were prepared according to the GRADE Evidence-to-Decision frameworks. Typical CIDP and CIDP variants were distinguished. The previous term "atypical CIDP" was replaced by "CIDP variants" because these are well characterized entities (multifocal, focal, distal, motor, or sensory CIDP). The levels of diagnostic certainty were reduced from three (definite, probable, possible CIDP) to only two (CIDP and possible CIDP), because the diagnostic accuracy of criteria for probable and definite CIDP did not significantly differ. Good Practice Points were formulated for supportive criteria and investigations to be considered to diagnose CIDP. The principal treatment recommendations were: (a) intravenous immunoglobulin (IVIg) or corticosteroids are strongly recommended as initial treatment in typical CIDP and CIDP variants; (b) plasma exchange is strongly recommended if IVIg and corticosteroids are ineffective; (c) IVIg should be considered as first-line treatment in motor CIDP (Good Practice Point); (d) for maintenance treatment, IVIg, subcutaneous immunoglobulin or corticosteroids are recommended; (e) if the maintenance dose of any of these is high, consider either combination treatments or adding an immunosuppressant or immunomodulatory drug (Good Practice Point); and (f) if pain is present, consider drugs against neuropathic pain and multidisciplinary management (Good Practice Point).

European Academy of Neurology/Peripheral Nerve Society guideline on diagnosis and treatment of chronic inflammatory demyelinating polyradiculoneuropathy: Report of a joint Task Force-Second revision

To revise the 2010 consensus guideline on chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Seventeen disease experts, a patient representative, and two Cochrane methodologists constructed 12 Population/Intervention/Comparison/Outcome (PICO) questions regarding diagnosis and treatment to guide the literature search. Data were extracted and summarized in GRADE summary of findings (for treatment PICOs) or evidence tables (for diagnostic PICOs). Statements were prepared according to the GRADE Evidence-to-Decision frameworks. Typical CIDP and CIDP variants were distinguished. The previous term "atypical CIDP" was replaced by "CIDP variants" because these are well characterized entities (multifocal, focal, distal, motor, or sensory CIDP). The levels of diagnostic certainty were reduced from three (definite, probable, possible CIDP) to only two (CIDP and possible CIDP), because the diagnostic accuracy of criteria for probable and definite CIDP did not significantly differ. Good Practice Points were formulated for supportive criteria and investigations to be considered to diagnose CIDP. The principal treatment recommendations were: (a) intravenous immunoglobulin (IVIg) or corticosteroids are strongly recommended as initial treatment in typical CIDP and CIDP variants; (b) plasma exchange is strongly recommended if IVIg and corticosteroids are ineffective; (c) IVIg should be considered as first-line treatment in motor CIDP (Good Practice Point); (d) for maintenance treatment, IVIg, subcutaneous immunoglobulin or corticosteroids are recommended; (e) if the maintenance dose of any of these is high, consider either combination treatments or adding an immunosuppressant or immunomodulatory drug (Good Practice Point); and (f) if pain is present, consider drugs against neuropathic pain and multidisciplinary management (Good Practice Point).

The value of sensory nerve conduction studies in the diagnosis of Guillain-Barré syndrome

Electrophysiology plays a determinant role in Guillain-Barré syndrome (GBS) diagnosis, classification, and prognostication. However, traditional electrodiagnostic (EDX) criteria for GBS rely on motor nerve conduction studies (NCS) and are suboptimal early in the course of the disease or in the setting of GBS variants. Sensory nerve conduction studies, including the sural-sparing pattern and the sensory ratio are not yet included in EDX criteria despite their well-established role in GBS diagnosis. The aim of this review is to discuss the diagnostic value of sensory NCS in GBS, their role in establishing the diagnosis and predicting the outcome according to the various subtypes of the disease.

Acute Axonal Motor Neuropathy With Completely Reversible Conduction Failure-Is It Really Axonal?

ABSTRACT

We present the case of a 24-year-old man with a 3-day history of limb weakness and flaccid tetraparesis, hyporreflexia, and gait difficulties (Hughes grade 3) in the examination. Electromyography at presentation revealed severe amplitude reduction in distal compound muscle action potentials of several nerves without features of demyelination, fulfilling electrodiagnostic criteria for acute axonal motor neuropathy. The patient was treated with immunoglobulin and recovered completely 21 days after symptom onset. Electromyography at this timepoint showed normalization of compound muscle action potentials without increased temporal dispersion. The electroclinical recovery profile in this patient is consistent with reversible conduction failure in distal nerve segments in detriment of axonal degeneration. Thus, it is an "axonal motor neuropathy" where axonopathy is unlikely, giving strength to the concept of "nodopathies/paranodopathies."

Diagnostic challenges in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) consists of a spectrum of autoimmune diseases of the peripheral nerves, causing weakness and sensory symptoms. Diagnosis often is challenging, because of the heterogeneous presentation and both mis- and underdiagnosis are common. Nerve conduction study (NCS) abnormalities suggestive of demyelination are mandatory to fulfil the diagnostic criteria. On the one hand, performance and interpretation of NCS can be difficult and none of these demyelinating findings are specific for CIDP. On the other hand, not all patients will be detected despite the relatively high sensitivity of NCS abnormalities. The electrodiagnostic criteria can be supplemented with additional diagnostic tests such as CSF examination, MRI, nerve biopsy, and somatosensory evoked potentials. However, the evidence for each of these additional diagnostic tests is limited. Studies are often small without the use of a clinically relevant control group. None of the findings are specific for CIDP, meaning that the results of the diagnostic tests should be carefully interpreted. In this update we will discuss the pitfalls in diagnosing CIDP and the value of newly introduced diagnostic tests such as nerve ultrasound and testing for autoantibodies, which are not yet part of the guidelines.

Association between chronic inflammatory demyelinating polyneuropathy and gastrointestinal malignancies

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an uncommon and under-recognized immune-mediated disorder of the peripheral nervous system. It is associated with both infectious and non-infectious etiologies and presents in several variant forms. In rare instances, CIDP has been reported in association with gastrointestinal (esophageal, hepatic, colorectal, and pancreatic) malignancies. The diagnosis of malignancy is typically preceded by weeks to months by that of CIDP, though the inverse may also be seen. As with other etiologies of CIDP, cases associated with gastrointestinal malignancies are often treated with corticosteroids, intravenous immunoglobulins, and/or plasma exchange, with improvement or resolution of neurological symptoms in the majority of cases. In this review, we provide a practical overview of CIDP, with an emphasis on recognizing the clinical association between CIDP and gastrointestinal malignancies.

Electrodiagnostic accuracy in polyneuropathies: supervised learning algorithms as a tool for practitioners

OBJECTIVE

The interpretation of electrophysiological findings may lead to misdiagnosis in polyneuropathies. We investigated the electrodiagnostic accuracy of three supervised learning algorithms (SLAs): shrinkage discriminant analysis, multinomial logistic regression, and support vector machine (SVM), and three expert and three trainee neurophysiologists.

METHODS

We enrolled 434 subjects with the following diagnoses: chronic inflammatory demyelinating polyneuropathy (99), Charcot-Marie-Tooth disease type 1A (124), hereditary neuropathy with liability to pressure palsy (46), diabetic polyneuropathy (67), and controls (98). In each diagnostic class, 90% of subjects were used as training set for SLAs to establish the best performing SLA by tenfold cross validation procedure and 10% of subjects were employed as test set. Performance indicators were accuracy, precision, sensitivity, and specificity.

RESULTS

SVM showed the highest overall diagnostic accuracy both in training and test sets (90.5 and 93.2%) and ranked first in a multidimensional comparison analysis. Overall accuracy of neurophysiologists ranged from 54.5 to 81.8%.

CONCLUSIONS

This proof of principle study shows that SVM provides a high electrodiagnostic accuracy in polyneuropathies. We suggest that the use of SLAs in electrodiagnosis should be exploited to possibly provide a diagnostic support system especially helpful for the less experienced practitioners.

Electrophysiological findings in immune checkpoint inhibitor-related peripheral neuropathy

OBJECTIVE

To report the electrodiagnostic features of immune checkpoint inhibitor (ICI)-related neuropathy.

METHODS

We retrospectively reviewed clinical presentations and electrodiagnostic features of 23 patients studied after receiving immune checkpoint inhibitors (ICIs). The presentations for electrodiagnostic evaluation included an acute neuropathy or neuromuscular junction disorder. We applied established electrodiagnostic criteria for polyneuropathy and acute demyelinating neuropathy.

RESULTS

We identified acute demyelinating neuropathy (13 cases), axonal sensory motor neuropathy (5), pure sensory neuropathy (4) and mononeuropathy (1). 13 patients had acute demyelinating neuropathy confirmed by demonstrating demyelination in 2 or more nerves; 3 additional patients had demyelination in only one nerve. Analysis of motor nerve conduction parameters revealed demyelination involving median and ulnar nerve distal motor latencies as well as median, ulnar and peroneal nerve conduction velocities. Conduction block was found in median, ulnar and peroneal nerves. The remaining one-third patients without demyelination had acute painful axonal neuropathy. Coexisting myopathic changes (6) and neuromuscular junction dysfunction (4) were also identified.

CONCLUSIONS

Our findings suggest that, while immune-mediated motor nerve demyelination is the primary underlying mechanism of ICI-related neuropathy, axonal painful neuropathy can also be an important presentation. Early recognition and effective intervention may reduce morbidity and permanent disability.

SIGNIFICANCE

Electrophysiological studies might be useful in the evaluation of ICI-related neuropathy.

Alleviating Sepsis-Induced Neuromuscular Dysfunction Linked With Acetylcholine Receptors by Agrin

BACKGROUND

Abnormal expression and distribution of nicotinic acetylcholine receptors (nAChRs) in skeletal muscle caused by sepsis can lead to neuromuscular dysfunction. Here, we asked whether neural agrin regulates nAChRs to ameliorate muscle function, which could be associated with the agrin/muscle-specific kinase pathway.

METHODS

Rats were subjected to cecal ligation and puncture (CLP) group, sham group, or control group to observe the alteration caused by sepsis. To verify the effect of improving function, rats were injected with agrin or normal saline intramuscularly after CLP. Electromyogram was used to measure neuromuscular function. Cytokines levels of serum and the expression of related proteins and mRNA were tested after treatment.

RESULTS

Compared with the rats in control or sham group, CLP-treated rats showed an acute inflammatory status and a reduction of neuromuscular dysfunction in tibialis anterior muscle, which was associated with abnormal expression in agrin/muscle-specific kinase pathway and increased expression of γ- and α7-nAChR. Exogenous agrin alleviated neuromuscular dysfunction and decreased the expression of γ- and α7-nAChR through agrin-related signaling pathway.

CONCLUSIONS

The decreased expression of agrin may lead to skeletal muscle dysfunction. Early enhancement of intramuscular agrin levels after sepsis may be a potential strategy for the treatment of sepsis-induced muscle dysfunction.

Clinical spectrum of the anti-GQ1b antibody syndrome: a case series of eight patients

Anti-GQ1b antibodies can be detected in the serum of patients with Miller Fisher syndrome (MFS) and its incomplete forms such as acute ophthalmoparesis (AO), acute ptosis, acute mydriasis, acute oropharyngeal palsy and acute ataxic neuropathy (AAN), as well as in pharyngeal-cervical-brachial weakness, Bickerstaff brainstem encephalitis (BBE) and in overlap syndromes with Guillain-Barré syndrome (MFS-GBS, BBE-GBS). We searched the laboratory medicine database at University Hospitals Leuven between 2002 and 2017 for serum samples with anti-GQ1b IgG antibodies. We identified eight patients with anti-GQ1b antibodies: 4 MFS, 2 AO, 1 MFS-GBS and 1 AAN. Mean age was 57 years and five patients were males. Preceding illness was present in all patients. At nadir, we observed most frequently gait disturbance, external ophthalmoplegia and absent/decreased reflexes. Albumino-cytological dissociation was present in four patients. Mean time between onset and nadir was 4 days, between onset and recovery 2.5 months. Five patients recovered completely and three had minor residual symptoms. Interestingly, one patient with AO experienced a second identical episode, approximately 1 year after the first one. Our data confirm the broad clinical spectrum associated with the presence of anti-GQ1b IgG antibodies. Incomplete MFS subtypes such as AO are a challenge for diagnosis, because of the limited (though invalidating) clinical presentation and the lack of confirming ancillary tests. Subacute onset of ophthalmoplegia and/or ataxia should urge the clinician to include the anti-GQ1b antibody syndrome in the differential diagnosis.

Chronic idiopathic axonal polyneuropathy: Prevalence of pain and impact on quality of life

BACKGROUND AND AIM

Chronic idiopathic axonal polyneuropathy (CIAP) is a term describing axonal neuropathies of insidious onset, with slow or no progression of the disease over at least 6 months and with no etiology being identified despite appropriate investigations. We aimed to establish the prevalence of pain in patients with CIAP and investigate the impact of pain on quality of life (QoL).

METHODS

All consecutive patients with CIAP attending a specialist neuropathy clinic were invited to participate. Pain was assessed via the DN4 questionnaire and the visual analogue scale (VAS). Overall Neuropathy Limitations Scale (ONLS) was used to assess the severity of neuropathy. The SF-36 questionnaire was used to measure participants' quality of life.

RESULTS

Fifty-five patients with CIAP were recruited (63.6% male, mean age 73.4 ± 8.7 years). Based on the DN4 questionnaire, peripheral neuropathic pain was present in 33 patients (60.0%). After having adjusted for age, gender and disease severity pain showed significant negative correlations with the energy/fatigue domain of QoL (β = -0.259, p = 0.049), with the emotional well-being domain (β = -0.368, p = 0.007) and the general health perception domain (β = -0.356, p = 0.007).

CONCLUSION

Pain is very prevalent in CIAP and is associated with poorer emotional well-being, worse general health perception, and increased fatigue.

The ulnar ratio as a sensitive and specific marker of acute inflammatory demyelinating polyneuropathy

OBJECTIVES

To explore the value of a novel sensory criterion, the ulnar ratio - defined as the SNAP amplitude of the palmar cutaneous (pUN) over that of the dorsal branch (dUN) of the ulnar nerve - as a predictor of Acute Inflammatory Demyelinating Polyneuropathy (AIDP).

METHODS

We prospectively included 22 patients with AIDP, 20 patients with diabetic peripheral neuropathy (DPN), and 18 controls. Eligible subjects underwent nerve conduction studies including, among others, the dUN, pUN, and sural nerve.

RESULTS

A sural sparing pattern was found in 72% of AIDP cases. The ulnar ratio was significantly lower in patients with AIDP compared to those with DPN or controls. The ROC curve area to discriminate AIDP (versus controls and diabetics together) was higher with the ulnar ratio and pUN compared to dUN. An ulnar ratio ≥ 0.78 seems to be the best threshold to rule out the diagnosis of AIDP, with a specificity of 100% and a sensitivity of 87%. The ulnar ratio was equally reliable in the subgroup of patients presenting within a week of symptoms onset.

CONCLUSION

The ulnar ratio is a highly sensitive and specific marker of AIDP and can help confirm the diagnosis when direct signs of demyelination are lacking.

SIGNIFICANCE

Incorporating specific sensory abnormalities, such as the ulnar ratio, in the electrodiagnostic criteria of AIDP could enhance their reliability.

Differences between acute-onset chronic inflammatory demyelinating polyneuropathy and acute inflammatory demyelinating polyneuropathy in adult patients

Acute inflammatory demyelinating polyneuropathy (AIDP) and acute-onset chronic inflammatory demyelinating polyneuropathy (A-CIDP) are conditions presenting overlapping clinical features during early stages (first 4 weeks), although the latter may progress after 8 weeks. The aim of this study was to identify predictive factors contributing to their differential diagnosis. Clinical records of adult patients with AIDP or A-CIDP diagnosed at our institution between January 2006 and July 2017 were retrospectively reviewed. Demographic characteristics, clinical manifestations, cerebrospinal-fluid (CSF) findings, treatment and clinical evolution were analyzed. Nerve conduction studies were performed in all patients with at least 12 months follow-up. A total of 91 patients were included (AIDP, n = 77; A-CIDP, n = 14). The median age was 55.5 years in patients with A-CIDP vs 43 years in AIDP (P = .07). The history of diabetes mellitus was more frequent in A-CIDP (29% vs 8%, P = .04). No significant differences between groups were observed with respect to: human immunodeficiency virus (HIV) status, presence of auto-immune disorder or oncologic disease. Cranial, motor and autonomic nerve involvement rates were similar in both groups. Patients in the A-CIDP group showed higher frequency of proprioceptive disturbances (83% vs 28%; P < .001), sensory ataxia (46% vs 16%; P = .01), and the use of combined immunotherapy with corticoids (29% vs 3%; P = .005). There were no significant differences in CSF findings, intensive care unit (ICU) admission, or mortality rates. During the first 8 weeks both entities are practically indistinguishable. Alterations in proprioception could suggest A-CIDP. Searching for markers that allow early differentiation could favor the onset of corticotherapy without delay.

Severe Acute Axonal Neuropathy Induced by Ciprofloxacin: A Case Report

Fluoroquinolones increase the risk of peripheral neuropathy. The present work aims to report a case of fluoroquinolone-related severe axonal neuropathy. The subject of this study was a 62-year-old man who exhibited generalized sensory disturbances 4 days after treatment by ciprofloxacin prescribed for urinary infection. Electrodiagnostic studies revealed severe motor-sensory axonal neuropathy with widespread fibrillation potentials in support of generalized motor polyradiculopathy. There was no evidence of conduction blocks or albuminocytologic dissociation in favor of an autoimmune inflammatory reaction. The only pathological biomarker was the reduction of serum folate. According to this case, we suggest that folate level could be routinely measured and supplementation should be performed in patients with fluoroquinolone-induced neuropathy.

Glial cell line-derived neurotrophic factor (GDNF) attenuates the peripheral neuromuscular dysfunction without inhibiting the activation of spinal microglia/monocyte

Background

Peripheral neuromuscular dysfunctions were found in elderly individuals, and spinal microglia/monocyte plays an important role on this process. This study aims to test whether the glial cell line-derived neurotrophic factor (GDNF) could attenuate age-related neuromuscular dysfunction by inhibiting the activation of spinal microglia/monocyte.

Methods

Male Sprague-Dawley rats were divided into an adult group and an aged group. The aged rats were intrathecally injected with normal saline (NS) and GDNF. All the rats were harvested 5 days after each injection. The muscular function was tested by compound muscle action potential, and the activation of microglia/monocyte was detected by immunofluorescence staining; cytokines were assayed by enzyme-linked immunosorbent assay; the expression level of GDNF and its known receptor GFR-α in the spinal cord, the expression level of neuregulin-1 (NRG-1) in the sciatic nerve, and the expression level of γ- and α7- ε-nicotinic acetylcholine receptors in the tibialis anterior muscle were measured by western blotting.

Results

The activated microglia/monocyte was found in the aged rats compared to the adult rats. The aged rats showed a significant neuromuscular dysfunction and cytokine release as well as increased expression of γ- and α7-nAChR. The protein expression of GDNF, GFR-α, and NRG-1 in the aged rats were significantly lower than that in the adult rats. However, the exogenous injection of GDNF could alleviate the neuromuscular dysfunction but not inhibit the activation of spinal microglia/monocyte. Furthermore, the levels of GFR-α and NRG-1 also increased after GDNF treatment.

Conclusion

The GDNF could attenuate the age-related peripheral neuromuscular dysfunction without inhibiting the activation of microglia/monocyte in the spinal cord.

Zika virus outbreak in New Caledonia and Guillain-Barré syndrome: a case-control study

Zika virus (ZIKV) infection has been associated with neurologic disorders including Guillain-Barré syndrome (GBS). In New Caledonia during the ZIKV outbreak (2014-2015), case-control and retrospective studies have been performed to assess the link between ZIKV and GBS. Among the 15 cases included, 33% had evidence of a recent ZIKV infection compared to only 3.3% in the 30 controls involved. All patients were Melanesian, had facial diplegia and similar neurophysiological pattern consistent with acute inflammatory demyelinating polyneuropathy, and recovered well. Furthermore, during the peak of ZIKV transmission, we observed a number of GBS cases higher than the calculated upper limit, emphasizing the fact that ZIKV is now a major trigger of GBS.

Serial electrophysiology in Guillain-Barré syndrome: A retrospective cohort and case-by-case multicentre analysis

OBJECTIVES

To assess the usefulness of serial electrophysiology in Guillain-Barré syndrome (GBS) in a multicenter setting and the reasons for change in electrodiagnostic subtypes with serial studies.

METHODS

We retrospectively analysed serial electrophysiology of 51 patients with GBS from 4 European centres. Proportions of subtypes were determined at each timing. Individual case analyses were also performed where diagnostic changes occurred with either criteria, to ascertain if changes were due to disease progression or criteria inadequacy.

RESULTS

At first study, comparing old vs new criteria, acute inflammatory demyelinating polyneuropathy (AIDP) was diagnosed in 70.6% vs 51%, axonal GBS in 15.7% vs 39.2%, equivocal forms in 11.8% vs 7.8%. At second study, AIDP was diagnosed in 72.5% vs 52.9%, axonal GBS in 9.8% vs 33.3%, equivocal forms in 15.7% vs 11.7%. Subtype proportions were unchanged, indicating serial studies did not, in the cohort, alter diagnostic rates for each subtype irrespective of criteria used. Individual review of cases where subtype electrodiagnosis changed indicated suboptimal specificity for AIDP/sensitivity for axonal GBS as main cause of diagnostic shifts with old criteria, whereas disease progression explained most changes with new criteria (55.6% vs 81.8%; P = .039).

CONCLUSIONS

Serial electrophysiology is unhelpful in GBS. Repeat studies cannot represent the gold standard as electrodiagnosis may alter due to disease progression. Changes in electrodiagnosis relate more often to disease progression with new criteria but are more frequently due to suboptimal sensitivity/specificity with old criteria. A single electrophysiological study using the most accurate available criteria appears sufficient in GBS.

Acute flaccid paralysis in South African children: Causes, respiratory complications and neurological outcome

AIM

To describe the causes, clinical presentation and neurological outcome of acute flaccid paralysis in children.

METHODS

A retrospective study in a tertiary paediatric hospital in South Africa. Data on clinical presentation, respiratory complications and long-term neurological outcomes of children presenting with acute flaccid paralysis were collected. Logistic regression analysis was applied to determine predictors for the need of mechanical ventilation.

RESULTS

The study included 119 patients, 99 of whom had Guillain-Barré syndrome (GBS); 47 patients (39.5%) required mechanical ventilation. Backward logistic regression analysis revealed that bulbar dysfunction (P < 0.001), autonomic dysfunction (P = 0.003) and upper limb paralysis (P = 0.038) significantly predicted the need for mechanical ventilation. EuroQol-5D scores of self-care problems and usual activities after discharge significantly declined over time.

CONCLUSIONS

In this large series from Africa, GBS was the main cause of acute flaccid paralysis in children and was associated with significant morbidity. Other causes of acute flaccid paralysis mimicking GBS were not uncommon and should be excluded in this setting.

Glial cell-derived neurotrophic factor alleviates sepsis-induced neuromuscular dysfunction by decreasing the expression of γ- and α7-nicotinic acetylcholine receptors in an experimental rat model of neuromyopathy

Sepsis-induced neuromuscular dysfunction results from up-regulation of the expression of γ- and α7-nicotinic acetylcholine receptors (nAChR). Although glial cell derived neurotrophic factor (GDNF) has been implicated in repairing and supporting neurons, little is known about the effects of GDNF on demyelination of nerves in sepsis. In this study, we tested the hypothesis that GDNF could alleviate sepsis-induced neuromuscular dysfunction by decreasing the expression of γ- and α7-nAChR in an experimental rat model of neuromyopathy. Rats were randomly divided into a sham group and a sepsis group. Levels of inflammatory factors, muscle function, and nicotinic acetylcholine receptors were tested in rats after cecal ligation and puncture (CLP). At 24 h after CLP, GDNF was injected around the sciatic nerve of sepsis rats, cytokines were detected by enzyme-linked immunosorbent assay (ELISA), and immunofluorescence staining was used to detect the expression of nAChRs. GDNF and its downstream effector (Erk1/2 and GFR-α), neuregulin-1 (NRG-1) and γ- and α7-nAChR were measured using Western blot analysis. The expression of GDNF reached a minimum at 24 h after CLP. Compared with the sham group, the release of cytokines and the expression of γ- and α7-nAChR were significantly increased in the sepsis group. The administration of GDNF significantly alleviated sepsis-induced neuromuscular dysfunction, as well as reducing the expression of γ- and α7-nAChR. In addition, the expression of Erk1/2, GFR-α, NRG-1 were significantly increased after GDNF treatment. GDNF administration may improve patient outcomes by reducing the demyelination of nerves and the expression of γ- and α7-nAChR.

Guillain-BarrÉ syndrome subtype diagnosis: A prospective multicentric European study

INTRODUCTION

There is uncertainty as to whether the Guillain-Barré syndrome (GBS) subtypes, acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and acute motor axonal neuropathy (AMAN), can be diagnosed electrophysiologically.

METHODS

We prospectively included 58 GBS patients. Electrodiagnostic testing (EDX) was performed at means of 5 and 33 days after disease onset. Two traditional and one recent criteria sets were used to classify studies as demyelinating or axonal. Results were correlated with anti-ganglioside antibodies and reversible conduction failure (RCF).

RESULTS

No classification shifts were observed, but more patients were classified as axonal with recent criteria. RCF and anti-ganglioside antibodies were present in both subtypes, more frequently in the axonal subtype.

DISCUSSION

Serial EDX has no effect on GBS subtype proportions. The absence of exclusive correlation with RCF and anti-ganglioside antibodies may challenge the concept of demyelinating and axonal GBS subtypes based upon electrophysiological criteria. Frequent RCF indicates that nodal/paranodal alterations may represent the main pathophysiology. Muscle Nerve, 2018.

Neurofascin antibodies in autoimmune, genetic, and idiopathic neuropathies

OBJECTIVE

To measure the frequency, persistence, isoform specificity, and clinical correlates of neurofascin antibodies in patients with peripheral neuropathies.

METHODS

We studied cohorts of patients with Guillain-Barre syndrome (GBS) or chronic inflammatory demyelinating polyneuropathy (CIDP) (n = 59), genetic neuropathy (n = 111), and idiopathic neuropathy (n = 43) for immunoglobulin (Ig) G and IgM responses to 3 neurofascin (NF) isoforms (NF140, NF155, and NF186) using cell-based assays.

RESULTS

Neurofascin antibodies were more common in patients with GBS/CIDP (14%, 8 of 59) compared to genetic neuropathy controls (3%, 3 of 111, p = 0.01). Seven percent (3 of 43) of patients with idiopathic neuropathy also had neurofascin antibodies. NF155 IgG4 antibodies were associated with CIDP refractory to IV immunoglobulin but responsive to rituximab, and some of these patients had an acute onset resembling GBS. NF186 IgG and IgM to either isoform were less specific. A severe form of CIDP, approaching a locked-in state, was seen in a patient with antibodies recognizing all 3 neurofascin isoforms.

CONCLUSIONS

Neurofascin antibodies were 4 times more frequent in autoimmune neuropathy samples compared to genetic neuropathy controls. Persistent IgG4 responses to NF155 correlated with severe CIDP resistant to usual treatments but responsive to rituximab. IgG4 antibodies against the common domains shared by glial and axonal isoforms may portend a particularly severe but treatable neuropathy. The prognostic implications of neurofascin antibodies in a subset of idiopathic neuropathy patients and transient IgM responses in GBS require further investigation.

Detection of proximal conduction blocks using a triple stimulation technique improves the early diagnosis of Guillain-Barré syndrome

OBJECTIVE

Current diagnostic electrophysiological criteria can miss the early stages of Guillain-Barré syndrome (GBS). We evaluated the diagnostic efficiency of the triple stimulation technique (TST) in highlighting proximal conduction blocks (CBs) in patients who do not meet the electrophysiological criteria for GBS.

METHODS

All patients with a diagnosis of clinical GBS referred to our center between September 2014 and January 2016 were included in the study. For patients who did not fulfill the electrophysiological criteria of GBS, we performed the TST examination.

RESULTS

Among the 44 included patients, 86% fulfilled the electrophysiological criteria of GBS during the initial nerve conduction study (NCS). The six remaining patients had proximal CBs revealed by TST examination. Therefore, a combination of a conventional NCS and the TST allowed 100% of the patients to be electrophysiologically diagnosed.

CONCLUSIONS

TST is useful for the diagnosis of GBS in association with NCS, particularly in the early stages of the disease.

SIGNIFICANCE

TST is a useful tool for GBS diagnosis at the early stages of the disease.

Role of "Sural Sparing" Pattern (Absent/Abnormal Median and Ulnar with Present Sural SNAP) Compared to Absent/Abnormal Median or Ulnar with Normal Sural SNAP in Acute Inflammatory Demyelinating Polyneuropathy

BACKGROUND

Sural sparing defined as absent/abnormal median sensory nerve action potential (SNAP) amplitude or absent/abnormal ulnar SNAP amplitude with a normal sural SNAP amplitude is thought to be a marker for inflammatory demyelinating polyneuropathies.

OBJECTIVE

If sural sparing pattern specifically defined as absent/abnormal median and ulnar SNAP amplitude with normal sural SNAP amplitude (AMUNS) is sensitive and specific when compared with either absent/abnormal median and normal sural (AMNS) or absent/abnormal ulnar and normal sural (AUNS) for acute inflammatory demyelinating polyneuropathy (AIDP), chronic inflammatory demyelinating polyneuropathy (CIDP), select non-diabetic axonopathies (AXPs), and diabetic neuropathies (DNs).

METHOD

Retrospective analysis from 2001 to 2010 on all newly diagnosed AIDP, CIDP, select non-diabetic AXP, and DN.

RESULTS

There were 20 AIDP and 23 CIDP. Twenty AXP and 50 DN patients between 2009 and 2010 were included as controls. AMUNS was seen in 65% of AIDP, 39% CIDP compared with 10% of AXP and 6% for DN with sensitivity of 51%, specificity of 92%, whereas the specificity of AMNS/AUNS was 73% and its sensitivity was 58%. If a patient has AMUNS they are >12 times more likely to have AIDP (p < 0.001).

CONCLUSION

Sural sparing is highly specific but not sensitive when compared with either AMNS or AUNS in AIDP but does not add to sensitivity or specificity in CIDP.

Ulinastatin inhibited sepsis-induced spinal inflammation to alleviate peripheral neuromuscular dysfunction in an experimental rat model of neuromyopathy

Sepsis initiates a neuroinflammatory cascade that contributes to spinal cord inflammation and behavioral impairment, and Toll-like receptor 4 (TLR4) is an important mediator of this cascade. In this study, we tested the hypothesis that ulinastatin (ULI) inhibits sepsis-induced spinal inflammation to alleviate peripheral neuromuscular dysfunction through the TLR4/myeloid differentiation factor 88 (MyD88)/NF-κB signaling pathway. Muscular function, spinal cord water content, and cytokine levels of spinal cord were tested in TLR4-inhibited rats subjected to cecal ligation and puncture (CLP). The normal rats were intrathecally injected with different concentrations of ULI or normal saline 60 min before CLP. At 24 h after CLP, the activation of microglia/macrophage was detected by immunofluorescence staining; and the cytokines were assayed by ELISA. The protein expression level of the TLR4 and its downstream effectors (MyD88 and NF-κB), the neuregulin-1, and the γ- and α7-nicotinic acetylcholine receptor was measured using western blotting. The protein expression of TLR4 in the spinal cord reached a maximum at 24 h post-CLP. Compared to the sham rats, the TLR4-inhibited rats showed attenuated functional impairment and cytokine release. ULI (5000 U/kg ) treatment pre-CLP significantly reduced the number of TLR4-positive microglia/macrophages as well as inflammatory mediator release in septic rats. Furthermore, the levels of TLR4, MyD88, and NF-κB and the expression level of γ-/α7-nicotinic acetylcholine receptors also decreased after ULI treatment. ULI administration may improve patient outcome by reducing the spinal inflammation through a mechanism involving the TLR4/MyD88/NF-κB signaling in sepsis.

Electroacupuncture alleviates neuromuscular dysfunction in an experimental rat model of immobilization

Immobilization-related skeletal muscle atrophy is a major concern to patients in Intensive Care Units and it has a profound effect on the quality of life. However, the underlying molecular events for the therapeutic effect of electroacupuncture to treat muscle atrophy have not been fully elucidated. Here we developed an immobilization mouse model and tested the hypothesis that skeletal muscle weakness may be caused by the increased expression of γ and α7 nicotinic acetylcholine receptors (nAChRs) on muscle cell membranes, while electroacupuncture could decrease the expression of γ and α7 nicotinic acetylcholine receptors. Compared with the rats in control, those treated with immobilization for 14 days showed a significant reduction of tibialis anterior muscle weight, muscle atrophy and dysfunction, which was associated with a significant decrease expression of neuregulin-1 and increased expression of γ- and α7-nAChR in tibialis anterior muscle. Electroacupuncture significantly enhanced the expression of neuregulin-1 and alleviated the muscle loss, while diminished the expression of γ- and α7-nAChR. Taken together, the beneficial effect of electroacupuncture may be attributed to suppressing γ- and α7-nAChR production, enhancing neuromuscular function and neuregulin-1 protein synthesis. These results suggest that electroacupuncture is a potential therapy for preventing muscle atrophy during immobilization.

Zika virus infection and Guillain-Barré syndrome: a review focused on clinical and electrophysiological subtypes

In 2016, we have seen a rapid emergence of Zika virus-associated Guillain-Barré syndrome (GBS) since its first description in a French-Polynesian patient in 2014. Current evidence estimates the incidence of GBS at 24 cases per 100 000 persons infected by Zika virus. This will result in a sharp rise in the number of GBS cases worldwide with the anticipated global spread of Zika virus. A better understanding of the pathogenesis of Zika-associated GBS is crucial to prepare us for the current epidemic. In this review, we evaluate the existing literature on GBS in association with Zika and other flavivirus to better define its clinical subtypes and electrophysiological characteristics, demonstrating a demyelinating subtype of GBS in most cases. We also recommend measures that will help reduce the gaps in knowledge that currently exist.

Differentiating Familial Neuropathies from Guillain-Barré Syndrome

Differentiating Guillain-Barré syndrome (GBS) from inherited neuropathies and other acquired peripheral neuropathies requires understanding the atypical presentations of GBS and its variant forms, as well as historical and physical features suggestive of inherited neuropathies. GBS is typically characterized by the acute onset of ascending flaccid paralysis, areflexia, and dysesthesia secondary to peripheral nerve fiber demyelination. The disorder usually arises following a benign gastrointestinal or respiratory illness, is monophasic, reaches a nadir with several weeks, and responds to immunomodulatory therapy. Inherited neuropathies with onset before adulthood, whose presentation may mimic Guillain-Barré syndrome, are reviewed.

Three novel mutations and genetic epidemiology analysis of the Gap Junction Beta 1 (GJB1) gene among Hungarian Charcot-Marie-Tooth disease patients

Pathogenic variants of the gap junction beta 1 (GJB1) gene are responsible for the Charcot-Marie-Tooth neuropathy X type 1 (CMTX1). In this study, we report the mutation frequency of GJB1 in 210 Hungarian CMT patients and the phenotype comparison between male and female CMTX1 patients. Altogether, 13 missense substitutions were found in the GJB1 gene. Among them, 10 have been previously described as pathogenic variants (p.Arg15Trp, p.Val63Ile, p.Leu89Val, p.Ala96Gly, p.Arg107Trp, p.Arg142Gln, p.Arg164Trp, p.Arg164Gln, p.Pro172Ala and p.Asn205Ser), while 3 were novel, likely pathogenic alterations (p.Val13Glu, p.Glu186Gly, p.Met194Ile). These variants were not present in controls and were predicted as disease causing by in silico analysis. The frequency of the variants was 6.7% in our cohort which refers to a common cause of hereditary neuropathy among Hungarian patients. In addition to the classical phenotype, CNS involvement was proved in 26.1% of the CMTX1 patients. GJB1 pathogenic alterations were found mainly in males but we also detected them in female probands. The statistical analysis of CMTX1 patients revealed a significant difference between the two genders regarding the age of onset, Charcot-Marie-Tooth neuropathy and examination scores.