Citations

ABSTRACTBackground and AimsNerve conduction studies (NCS) are integral to diagnosing chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), but their role in predicting treatment outcomes remains underexplored. This study evaluates NCS changes at first follow‐up (first NCS changes) as predictors of treatment success in CIDP, focusing on their correlation with clinical outcomes over time.MethodsNewly diagnosed CIDP patients meeting the 2021 EAN/PNS criteria were retrospectively evaluated. Baseline and first follow‐up NCS parameters were compared with clinical outcomes, assessed by the Neuropathy Impairment Score (NIS) and Inflammatory Neuropathy Cause and Treatment (INCAT) disability score. All patients received first‐line immunotherapy (intravenous immunoglobulin, corticosteroids, or plasma exchange).ResultsOf 39 treated patients, 26 (66.7%) were responders based on improving NIS trends, while 13 (33.3%) were nonresponders. Responders showed significant improvements at the first follow‐up in fibular compound muscle action potential (CMAP) amplitude, ulnar CMAP amplitude, summated CMAP amplitudes, and fibular motor conduction velocity. Changes in fibular CMAP amplitude consistently correlated with NIS (R = −0.8 to −0.6, p ≤ 0.004) and INCAT disability score improvements (R = −0.6 to −0.3, p ≤ 0.032) across all follow‐up intervals up to 60 months. Ulnar and summated CMAP amplitude changes also correlated with clinical outcomes, though their associations were less sustained than those of fibular CMAP amplitude.InterpretationThe first change in fibular CMAP amplitude is a reliable biomarker for predicting CIDP treatment response, with ulnar and summated CMAP amplitudes as alternatives when the fibular response is absent. Our findings highlight the utility of first NCS changes in monitoring and predicting treatment outcomes in CIDP.

ABSTRACTBackground and AimsLeucine Zipper 4 (LUZP4)‐immunoglobulin G (IgG) is a novel antibody implicated in germ cell tumor‐related paraneoplastic neurologic syndrome. We report a case of painful, progressive tetraparesis associated with testicular seminoma and LUZP4‐IgG seropositivity.Case ReportA 51‐year‐old male presented with a 5‐week history of lower limb predominant progressive weakness. Nerve conduction studies (NCS) and electromyography (EMG) revealed a subacute axonal polyradiculoneuropathy. MRI lumbar spine showed thickening of the cauda equina and enhancement of the lower thoracic spinal cord/conus. Cerebrospinal fluid (CSF) showed a lymphocytic pleocytosis, three oligoclonal bands, and mildly elevated protein. Initial treatment with intravenous immunoglobulin (IVIG) and prednisone produced temporary improvement. CT targeted retroperitoneal lymph node biopsy revealed a seminoma, which was treated with orchiectomy and chemotherapy. The testicular tissue was consistent with a regressed germ cell tumor. His course was subsequently refractory to IVIG, prednisone, and plasma exchange. LUZP4 antibodies were detected in serum, prompting treatment with cyclophosphamide and prednisone. At the 4‐month follow‐up, the patient had significant improvement in hand strength and had transitioned from walker to cane.InterpretationLUZP4‐IgG seropositivity and identification of retroperitoneal seminoma confirmed a paraneoplastic neurologic syndrome, which is a CD8+ T‐cell‐mediated disorder. Aggressive immunotherapy was initiated, resulting in clinical improvement. This case underscores the importance of identifying specific serologic biomarkers that can inform therapeutic decisions and improve outcomes.

Abstract Background Tafamidis is a kinetic stabilizer that binds to the transthyretin (TTR) gene, inhibiting its dissociation. It is the only disease-modifying treatment for hereditary TTR amyloidosis with peripheral neuropathy (ATTRv-PN) available in the National Therapeutic Form (Formulário Terapêutico Nacional, FTN, in Portuguese) of the Brazilian Unified Health System (Sistema Único de Saúde, SUS, in Portuguese). Objective To assess if the efficacy and safety of tafamidis in the Brazilian real-world experience are comparable to the results of clinical trials. Methods We retrospectively studied all patients with ATTRv-PN evaluated at our center from September 2011 to March 2022 (data cut-off) who were initiated on tafamidis and had at least 1 follow up visit 6 months after the initiation of the drug treatment. Neurologic and functional outcomes were compared from day 1 (D1) of the tafamidis treatment (baseline) to the last follow-up. Results In total, 33 patients were included, 18 (55%) of whom were female. All patients were carriers of the V30M mutation of ATTRv-PN, and 20 (61%) presented early onset (EO) ATTRv-PN. At baseline, the median age of the sample was of 40 (interquartile range [IQR]: 36–68) years, the median Neuropathy Impairment Score (NIS) was of 10 (6–24) points, and the median body mass index (BMI) was of 26 (23–28) kg/m2. The mean follow-up time was of 3.4 years. At the last follow-up, the BMI, the neurological impairment, and the level of disability slightly worsened compared with baseline, while the findings of the nerve conduction studies remained stable. These same results were observed across EO and late-onset (LO) ATTRv-PN patients. A total of 25 (75.8%) patients were considered responders, and 8 (24.2%), non-responders. Conclusion The efficacy and safety of tafamidis reported in clinical trials is expandable to the Brazilian real-world scenario in EO and late-onset (LO) ATTRv-PN.

Importance There is a lack of long-term efficacy and safety data on hereditary transthyretin amyloidosis with polyneuropathy (hATTR-PN) and on RNA interference (RNAi) therapeutics in general. This study presents the longest-term data to date on patisiran for hATTR-PN. Objective To present the long-term efficacy and safety of patisiran in adults with hATTR-PN. Design, Setting, and Participants This global open-label extension (OLE) of the APOLLO randomized clinical trial and phase 2 OLE study enrolled patients from 43 hospitals or clinical centers across 19 countries between July 2015 and August 2017, with follow-up until November 2022. Of 212 eligible patients with hATTR who completed the phase 3 APOLLO or phase 2 OLE parent studies, 211 enrolled in and 138 completed the global OLE. Intervention Patisiran, 0.3 mg/kg, intravenously once every 3 weeks for up to 5 years. Main Outcomes and Measures Outcomes evaluated at year 5 of the global OLE included disability (polyneuropathy disability [PND] score); polyneuropathy severity (Neuropathy Impairment Score [NIS]), nutritional status (modified body mass index [mBMI]), quality of life (Norfolk Quality of Life–Diabetic Neuropathy [Norfolk QOL-DN]), and Rasch-Built Overall Disability Scale (R-ODS), with no statistical hierarchy. Safety, survival probability, and mortality were also assessed. Results At the global OLE baseline, the mean (SD) age was 61.3 (12.3) years, and 156 patients (73.9%) were male. In 138 patients completing the study, PND scores remained stable or improved in 89 patients (65.0%), NISs showed a mean (SD) change of 10.9 (14.7), and mean (SD) mBMI (calculated as weight in kilograms divided by height in meters squared times serum albumin in grams per liter) increased by 46.4 (120.7) over 5 years from baseline. Norfolk QOL-DN and R-ODS scores showed mean (SD) changes of 4.1 (16.7) and –3.7 (6.2), respectively. Adverse events (AEs) leading to study withdrawal occurred in 47 patients (22.3%). Infusion-related reactions were the most common treatment-related AE (n = 34 [16.1%]). Overall, 41 patients (19.4%) died during the study. Patisiran treatment in the parent study and low familial amyloid polyneuropathy score at parent study baseline were associated with significantly improved survival. Conclusions and Relevance In the longest study of an RNAi therapeutic for any disease, patisiran treatment resulted in modest changes for patients with hATTR-PN with an acceptable safety profile. These results highlight the importance of initiating early treatment for hATTR and the potential of RNAi therapeutics in medicine. Trial Registration ClinicalTrials.gov Identifier: NCT02510261

ABSTRACTBackground and AimsChronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is difficult to distinguish from mimicking disorders, with misdiagnosis resulting in IVIG overutilization. We evaluate a clinical‐electrophysiological model to facilitate CIDP versus mimic neuropathy prediction.MethodsUsing the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) 2021 CIDP guidelines we derived 26 clinical and 144 nerve conduction variables. The model was generated and validated utilizing total CIDP (n = 129) and mimics (n = 309); including (1) IgG4‐nodopathies; (2) POEMS (polyneuropathy–organomegaly–endocrinopathy–monoclonal protein‐skin changes); (3) anti‐myelin‐associated‐glycoprotein; (4) paraneoplastic; (5) Waldenström B‐cell lymphoma; (6) diabetic neuropathies; (7) amyloidosis; (8) Charcot–Marie–Tooth; (9) motor neuropathies/neuronopathies; and (10) idiopathic‐inflammatory‐myopathies.ResultsWe analyzed 9282 clinical and 51 408 electrophysiological data points. Univariate analysis identified 11 of 26 clinical variables with significant odds ratios. A multivariate regression model using four clinical and two electrophysiologic variables achieved 93% area‐under‐curve (95% CI 91–95): progression over 8 weeks (OR 40.66, 95% CI 5.31–311.36), absent autonomic involvement (OR 17.82, 95% CI 2.93–108.24), absent muscle atrophy (OR 16.65, 95% CI 3.27–84.73), proximal weakness (OR 3.63, 95% CI 1.58–8.33), ulnar motor conduction velocity slowing < 35.7 m/s (OR 5.21, 95% CI 2.13–12.76), and ulnar motor conduction block (OR 13.37, 95% CI 2.47–72.40). A web‐based probability calculator (https://news.mayocliniclabs.com/cidp‐calculator/) was developed, with 100% sensitivity and 68% specificity at a 92% probability threshold. Specificity improved to 93% when considering “red flags,” electrophysiologic criteria, and laboratory testing.InterpretationA probability calculator using clinical electrophysiological variables assists CIDP differentiation from mimics, with scores below 92% unlikely to have CIDP. The highest specificity is achieved by considering clinical “red flags,” electrophysiologic demyelination, and laboratory testing.

Subacute, painful weakness is a common problem encountered by neurologists and can be associated with systemic symptoms. The patient presented with 6 weeks of progressive neuropathic pain followed by sensory changes and distal-predominant weakness. This case reviews the broad differential for such a presentation and a comprehensive, stepwise approach to diagnosis. Particular attention is paid to the potentially treatable polyradiculoneuropathies, including more recently recognized immune-mediated etiologies. Through this stepwise approach, we review how a definitive diagnosis was made.

Abstract Vasculitic neuropathy is caused by inflammatory destruction of nerve blood vessels resulting in nerve ischaemia. Nerve vasculitis can be divided into two categories based on vessel size: large-arteriole vasculitis (≥75 µm) and microvasculitis (&lt;75 µm). Herein, we characterize the clinical features of nerve large-arteriole vasculitis in comparison to nerve microvasculitis. This is a retrospective cohort study of patients evaluated and biopsied at Mayo sites between 2001 and 2020. We collected clinical and histopathological data from patients whose nerve biopsies were either diagnostic or highly suggestive of nerve vasculitis. Two hundred and seventy-eight cases were identified: 125 cases of large-arteriole vasculitis and 153 cases of microvasculitis. Nerve large-arteriole vasculitis presented with a more acute (50.4% versus 26.8%) versus chronic onset (33.6% versus 57.5%) than nerve microvasculitis (P = 0.0001). Nerve microvasculitis had longer mean time to diagnosis (10.5 versus 4.3 months; P &lt; 0.0001) and longer time to plateau (8.9 versus 3.5 months; P &lt; 0.0001). Nerve large-arteriole vasculitis typically presented as distal asymmetric polyneuropathy (48.0%), whereas nerve microvasculitis typically presented as radiculoplexus neuropathy/polyradiculoneuropathy (more proximal involvement of shoulder and thigh) (43.8%) (P &lt; 0.0001). Systemic autoimmune disease was more common in nerve large-arteriole vasculitis (70.4% versus 22.9%, odds ratio, 8.0; 95% confidence interval, 4.7–13.7; P &lt; 0.0001). Nerve microvasculitis was significantly related to non-systemic vasculitis (71% versus 23%, odds ratio, 7.9; 95% confidence interval, 4.6–13.6; P &lt; 0.0001). Nerve microvasculitis had more autonomic involvement (24.2% versus 7.2%, odds ratio, 4.1; 95% confidence interval, 1.9–8.9; P = 0.0002). Nerve large-arteriole vasculitis and nerve microvasculitis have different but overlapping clinical features. Nerve large-arteriole vasculitis usually presents with acute onset, distal asymmetric polyneuropathy, associated with other autoimmune diseases and systemic involvement. In contrast, nerve microvasculitis usually presents with a subacute/chronic onset, as radiculoplexus neuropathy/polyradiculopathy (distal and proximal pattern) with autonomic involvement, and is more often a form of non-systemic vasculitis.