Pinto, Marcus Vinícius

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.