Electrodiagnosis of Guillain-Barre syndrome in the International GBS Outcome Study: Differences in methods and reference values.

OBJECTIVE: To describe the heterogeneity of electrodiagnostic (EDx) studies in Guillain-Barré syndrome (GBS) patients collected as part of the International GBS Outcome Study (IGOS). METHODS: Prospectively collected clinical and EDx data were available in 957 IGOS patients from 115 centers. Only the first EDx study was included in the current analysis. RESULTS: Median timing of the EDx study was 7 days (interquartile range 4-11) from symptom onset. Methodology varied between centers, countries and regions. Reference values from the responding 103 centers were derived locally in 49%, from publications in 37% and from a combination of these in the remaining 15%. Amplitude measurement in the EDx studies (baseline-to-peak or peak-to-peak) differed from the way this was done in the reference values, in 22% of motor and 39% of sensory conduction. There was marked variability in both motor and sensory reference values, although only a few outliers accounted for this. CONCLUSIONS: Our study showed extensive variation in the clinical practice of EDx in GBS patients among IGOS centers across the regions. SIGNIFICANCE: Besides EDx variation in GBS patients participating in IGOS, this diversity is likely to be present in other neuromuscular disorders and centers. This underlines the need for standardization of EDx in future multinational GBS studies.

Lenalidomide Treatment for Thalidomide-refractory POEMS Syndrome: A Prospective Single-arm Clinical Trial.

Objective A randomized controlled trial has shown the efficacy of thalidomide against polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome; however, there are still refractory patients. We studied the effects of lenalidomide, a derivative of thalidomide, on patients refractory to thalidomide. Methods This prospective single-arm trial evaluated the safety and efficacy of lenalidomide plus dexamethasone in refractory or recurrent patients with POEMS syndrome. The regimen was administered as six 28-day cycles with lenalidomide on days 1-21 (15 mg in cycle 1, and 25 mg in cycle 2-6) plus dexamethasone once a week (20 mg). The primary endpoints were the rate of reduction in the serum vascular endothelial growth factor (VEGF) level at 24 weeks and the incidence of adverse events. This trial was registered with ClinicalTrial.gov, NCT02193698. Results Between July 2014 and December 2015, five men were enrolled. All patients had been refractory to thalidomide plus dexamethasone for more than 24 weeks. The mean rate of reduction in the serum VEGF level at 24 weeks was 59.6%±8.3% (p=0.0003). The mean serum VEGF level decreased from 2,466±771 pg/mL to 974±340 pg/mL. No serious adverse events were observed, and all patients completed six cycles treatment. Discussion Lenalidomide is a therapeutic option for thalidomide-refractory patients with POEMS syndrome.

Membrane property changes in most distal motor axons in chronic inflammatory demyelinating polyneuropathy.

INTRODUCTION: Distal nerve terminals, where the blood-nerve barrier is anatomically deficient, are preferentially affected in immune-mediated neuropathies. Excitability alterations near the motor nerve terminals may be more prominent than the nerve trunk in typical chronic inflammatory demyelinating polyneuropathy (CIDP). METHODS: In 20 patients with typical CIDP, motor nerve excitability testing was performed at the motor point and wrist of the ulnar nerve, and results were compared with those in 20 healthy persons. RESULTS: Chronic inflammatory demyelinating polyneuropathy patients showed greater threshold changes in hyperpolarizing threshold electrotonus at the motor point (P < .05) but not at the wrist. Strength-duration time constant did not show significant differences between CIDP and controls at both sites. DISCUSSION: Axonal property changes in CIDP are more prominent in distal portions of axons compared with the nerve trunk, presumably due to salient demyelination near the distal nerve terminals. Motor point excitability measurements could elucidate underlying pathophysiology in immune-mediated neuropathies.

Prevalence, clinical profiles, and prognosis of POEMS syndrome in Japanese nationwide survey.

OBJECTIVE: To elucidate current epidemiological, clinical profiles, and treatment of polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome. METHODS: We conducted a nationwide survey in 2015 using an established epidemiologic method. Data processing sheets were sent to all neurology and hematology specialist departments throughout Japan to identify patients with POEMS who were seen between April 2012 and March 2015. RESULTS: The estimated number of patients with POEMS was 392 (95% confidence interval [CI] 320-464), and the prevalence was 0.3 per 100,000. Detailed clinical profiles were available for 167 patients. Median age at onset was 54 years (range, 21-84 years), and the ratio of male to female was 1.5. All patients showed polyneuropathy; 89% had monoclonal plasma cell proliferation; and 84% had elevated vascular endothelial growth factor level in whom pretreatment serum or plasma was available (n = 87). Other common features were skin changes (84%), edema/effusion (81%), and organomegaly (76%). A total of 160 patients were treated with any of the following: radiation, corticosteroids, melphalan, thalidomide, lenalidomide, bortezomib, or autologous stem cell transplantation. Primary therapeutic options were thalidomide (n = 86) and autologous stem cell transplantation (n = 71). Thirty-nine patients (24%) were initially treated with corticosteroid alone. The 10-year overall survival was 93% (95% CI 86%-96%). DISCUSSION: This study showed current epidemiologic and clinical status of POEMS syndrome in Japan. A quarter of patients were still inadequately treated with corticosteroid alone, whereas either autologous stem cell transplantation or immunomodulatory drugs improved the prognosis.

Hidden Charcot-Marie-Tooth 1A as Revealed by Peripheral Nerve Imaging.

Peripheral nerve imaging techniques have recently increasingly revealed their usefulness. We herein describe a man who had a subacute progression of symptom, diffuse and prominent proximal demyelination and conduction block, suggesting a diagnosis of inflammatory demyelinating polyneuropathy. Additional nerve imaging techniques revealed homogeneous and prominent nerve hypertrophy without proximal accentuation and the findings implied inherited polyneuropathies. Intravenous immunoglobulin was administered, and both the symptoms of weakness and findings of nerve conduction studies (NCS) improved. Subsequent genetic testing unveiled Charcot-Marie-Tooth 1A. To diagnose peripheral nerve disorders, a careful history, physical examination and NCS are essential diagnostic tools, but the findings of this case suggest the importance of nerve imaging techniques in clinical situations.

Proposal of new clinical diagnostic criteria for POEMS syndrome.

OBJECTIVE: To propose the optimal diagnostic criteria for polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes (POEMS) syndrome using appropriate statistical methods and disease controls. METHODS: This retrospective cohort study included 104 consecutive patients with suspected POEMS syndrome, among whom a gold standard group of 60 patients with definitive POEMS syndrome diagnosis were followed for at least 12 months to strictly exclude other disorders mimicking POEMS syndrome and to confirm response to POEMS syndrome-specific treatment. Thirty patients with chronic inflammatory demyelinating polyradiculoneuropathy (demyelinating polyradiculoneuropathy controls) and 30 with multiple myeloma or immunoglobulin light chain amyloidosis (monoclonal plasma cell proliferation controls) were also included. Logistic regression analyses were performed to determine optimal combination of clinical and laboratory abnormalities, characteristic of POEMS syndrome. RESULTS: The diagnostic criteria were statistically defined as the presence of the three major criteria (polyneuropathy (typically demyelinating), monoclonal plasma cell proliferative disorder and elevated vascular endothelial growth factor) and at least two of the four minor criteria (oedema/effusion, skin changes, organomegaly and sclerotic bone lesions), based on best performance by area under the receiver operating characteristic curve analyses. The sensitivity and specificity were 100% and 100%, respectively; the diagnostic accuracy of the proposed criteria was equivalent to somewhat complicated previous criteria. CONCLUSIONS: The statistically defined, simple diagnostic criteria for POEMS syndrome could accelerate early diagnosis and treatment, thereby contribute to better outcome in patients with this serious disease. Prospective larger studies are required to confirm the validity.

Safety and efficacy of eculizumab in Guillain-Barré syndrome: a multicentre, double-blind, randomised phase 2 trial.

BACKGROUND: Despite the introduction of plasmapheresis and immunoglobulin therapy, many patients with Guillain-Barré syndrome still have an incomplete recovery. Evidence from pathogenesis studies suggests the involvement of complement-mediated peripheral nerve damage. We aimed to investigate the safety and efficacy of eculizumab, a humanised monoclonal antibody against the complement protein C5, in patients with severe Guillain-Barré syndrome. METHODS: This study was a 24 week, multicentre, double-blind, placebo-controlled, randomised phase 2 trial done at 13 hospitals in Japan. Eligible patients with Guillain-Barré syndrome were aged 18 years or older and could not walk independently (Guillain-Barré syndrome functional grade 3-5). Patients were randomly assigned (2:1) to receive 4 weeks of intravenous immunoglobulin plus either eculizumab (900 mg) or placebo; randomisation was done via a computer-generated process and web response system with minimisation for functional grade and age. The study had a parallel non-comparative single-arm outcome measure. The primary outcomes were efficacy (the proportion of patients with restored ability to walk independently [functional grade ≤2] at week 4) in the eculizumab group and safety in the full analysis set. For the efficacy endpoint, we predefined a response rate threshold of the lower 90% CI boundary exceeding 50%. This trial is registered with ClinicalTrials.gov, number, NCT02493725. FINDINGS: Between Aug 10, 2015, and April 21, 2016, 34 patients were assigned to receive either eculizumab (n=23) or placebo (n=11). At week 4, the proportion of the patients able to walk independently (functional grade ≤2) was 61% (90% CI 42-78; n=14) in the eculizumab group, and 45% (20-73; n=5) in the placebo group. Adverse events occurred in all 34 patients. Three patients had serious adverse events: two in the eculizumab group (anaphylaxis in one patient and intracranial haemorrhage and abscess in another patient) and one in the placebo group (depression). The possibility that anaphylaxis and intracranial abscess were related to eculizumab could not be excluded. No deaths or meningococcal infections occurred. INTERPRETATION: The primary outcome measure did not reach the predefined response rate. However, because this is a small study without statistical comparison with the placebo group, the efficacy and safety of eculizumab could be investigated in larger, randomised controlled trials. FUNDING: The Japan Agency for Medical Research and Development, Ministry of Health, Labor and Welfare, and Alexion Pharmaceuticals.

Altered cerebral blood flow in the anterior cingulate cortex is associated with neuropathic pain.

OBJECTIVE: To assess the cerebral blood flow (CBF) in patients with diabetic neuropathic pain, and its changes after duloxetine therapy. METHODS: Using iodine-123-N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (IMP-SPECT), we performed a cross-sectional study of 44 patients with diabetes, and compared CBF in those with (n = 24) and without neuropathic pain (n = 20). In patients with neuropathic pain, we also longitudinally assessed changes in CBF 3 months after treatment with duloxetine. RESULTS: IMP-SPECT with voxel-based analyses showed a significant increase in cerebral blood flow in the right anterior cingulate cortex and a decrease in the left ventral striatum in patients with neuropathic pain, compared with those without pain. After duloxetine treatment, volume of interest analyses revealed a decrease in cerebral blood flow in the anterior cingulate cortex in patients with significant pain relief but not in non-responders. Furthermore, voxel-based whole brain correlation analyses demonstrated that greater baseline CBF in the anterior cingulate cortex was associated with better pain relief on the numerical rating scale. CONCLUSIONS: Our results suggest that the development of neuropathic pain is associated with increased activity in the anterior cingulate cortex, and greater baseline activation of this region may predict treatment responsiveness to pharmacological intervention. TRIAL REGISTRATION NUMBER: UMIN000017130;Results.

Pain-related evoked potentials after intraepidermal electrical stimulation to Aδ and C fibers in patients with neuropathic pain.

Neuropathic pain can result from neuronal hyperexcitability and complex interactions of the nociceptive pathways. Intraepidermal electrical stimulation (IES) is a novel technique that can selectively activate Aδ and C fibers. To investigate patterns of changes in Aδ- and C-mediated brain responses in patients with neuropathic pain using IES, we recorded pain-related evoked potential (PREP) after IES of Aδ and C fibers in 20 patients with neuropathic pain and 15 age-matched healthy volunteers. We evaluated PREP latencies, amplitudes, and amplitude ratios of PREPs after C/Aδ-fiber stimulation. PREP amplitudes after Aδ-fiber stimulation tended to be smaller in the patient group, whereas there were no significant differences in amplitudes after C-fiber stimulation between the patient and normal control groups. PREP amplitude ratios after C/Aδ-fiber stimulation were significantly greater in the patient group than in the control group, and the higher ratio tended to be associated with a greater visual analog scale score. Patients with neuropathic pain had a tendency towards decreased Aδ amplitudes and significantly increased C/Aδ PREP amplitude ratios and this ratio appeared to be associated with the intensity of pain. Our findings suggest that decreased inhibition of the Aδ to C nociceptive systems is associated with generation of neuropathic pain.

A Prospective, Multicenter, Randomized Phase II Study to Evaluate the Efficacy and Safety of Eculizumab in Patients with Guillain-Barré Syndrome (GBS): Protocol of Japanese Eculizumab Trial for GBS (JET-GBS).

BACKGROUND: Guillain-Barré syndrome (GBS) is an immune-mediated neuropathy that causes acute flaccid paralysis. Immunoglobulin and plasma exchange are established treatments for GBS; however, a substantial number of patients, particularly those with severe disease, have poor recovery and residual deficits. Recent studies suggest that complement activation plays a pivotal role in GBS-associated axonal degeneration, and eculizumab is a humanized monoclonal antibody that specifically binds to complement component 5 and potently inhibits complement activation. OBJECTIVE: This clinical trial aims to evaluate the efficacy and safety of eculizumab, a humanized monoclonal antibody directed against complement component 5, for treatment of GBS. METHODS: The Japanese Eculizumab Trial for GBS (JET-GBS) is a prospective, multicenter, placebo-controlled, double-blind, randomized phase II study conducted at 13 tertiary neurology centers and is funded by the Japan Agency for Medical Research and Development. A total of 33 GBS patients unable to walk independently within 2 weeks from symptom onset (Hughes functional grade 3-5) were randomized at a 2:1 ratio to receive either intravenous eculizumab (900 mg/day) or placebo once weekly for 4 weeks, followed by 20 weeks of follow-up. The primary endpoint for efficacy is the proportion of patients who regain their ability to walk without aid at 4 weeks after the first dose of the study treatment, while primary safety outcomes are the incidence of adverse events and serious adverse events during the trial. RESULTS: Enrollment for the trial began in August 2015. This trial is still ongoing. All participants have been enrolled, and follow-up will be completed in October 2016. CONCLUSIONS: This study is the first to investigate the efficacy and safety of eculizumab for GBS. In case of a positive result, we will plan a phase III trial to investigate this issue in a larger number of patients. CLINICALTRIAL: UMIN Clinical Trials Registry UMIN 000018171; https:/upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function= brows&action=brows&type=summary&language=J&recptno=R000020978 (Archived by WebCite at http://www.webcitation.org/ 6lTiG8ltG). Clinical Trials.gov NCT02493725; https://clinicaltrials.gov/ct2/show/NCT02493725 (Archived by WebCite at http://www.webcitation.org/6lVJZXKSL).

Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis.

Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS.

Altered axonal excitability properties and nerve edema in POEMS syndrome.

OBJECTIVE: POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes) syndrome is a rare cause of demyelinating neuropathy with upregulation of vascular endothelial growth factor (VEGF). This study aimed to elucidate axonal excitability properties and their relation to VEGF levels and nerve edema in POEMS neuropathy. METHODS: Axonal excitability measurement and nerve ultrasound were performed in the median nerve of 33 patients with POEMS syndrome. Serum VEGF levels were measured by ELISA. RESULTS: Compared with normal subjects (n=87), POEMS patients showed longer strength-duration time constant, fanning-out of threshold electrotonus curves, and greater threshold changes in a hyperpolarizing current-threshold relationship. Nerve ultrasound showed significant enlargement in POEMS patients. Serum VEGF levels and the extent of nerve edema partly correlated with nerve conduction slowing, as well as persistent sodium currents and inward rectification. CONCLUSIONS: In POEMS syndrome, patterns of changes in excitability properties could suggest increased persistent sodium currents, and impaired potassium and inward rectifying channels. The findings were not consistent with depolarization due to nerve edema and compression ischemia. SIGNIFICANCE: In addition to demyelination, nerve edema induced by upregulated VEGF, and upregulated inflammatory cytokines could modulate profiles of POEMS neuropathy.