{"title":"Kappa index in the diagnostic work-up of autoimmune encephalitis","authors":"","doi":"10.1016/j.jns.2024.123146","DOIUrl":null,"url":null,"abstract":"<div><h3>Background</h3><p>The presence of inflammatory changes in the cerebrospinal fluid (CSF), including immunoglobulin intrathecal synthesis (IS), can support the diagnosis of autoimmune encephalitis (AE) and allow prompt treatment. The main aim of our study was to calculate the Kappa index as a marker of IS, in patients with AE.</p></div><div><h3>Methods</h3><p>Charts of patients undergoing a diagnostic work-up for suspected AE between 2009 and 2023 were reviewed and the Graus criteria applied. CSF and serum kappa free light chains were determined using the Freelite assay (The Binding Site Group) and the turbidimetric Optilite analyzer.</p></div><div><h3>Results</h3><p>We identified 34 patients with “definite” AE (9 anti-NMDAR AE and 25 limbic AE) and nine patients with “possible” AE. Five patients (15%) with definite AE had pleocytosis and twelve (34%) showed CSF-restricted oligoclonal bands (OCB) at isoelectric focusing. The Kappa index was >6 in 29.4% and > 3 in 50% of the definite AE patients. It was elevated (>3) in 36.4% of patients with definite AE who resulted negative to OCB testing and was the only altered parameter suggestive of an ongoing inflammatory process in the CNS in three definite AE patients with otherwise normal CSF findings (i.e. normal cell count and protein levels, no OCBs). In the possible AE group, one patient had a Kappa index >3 in the absence of OCB.</p></div><div><h3>Conclusions</h3><p>The Kappa index could be useful, as a more sensitive marker of IS and as a supportive marker of neuroinflammation, in the diagnostic work-up of suspected AE.</p></div>","PeriodicalId":17417,"journal":{"name":"Journal of the Neurological Sciences","volume":null,"pages":null},"PeriodicalIF":3.6000,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the Neurological Sciences","FirstCategoryId":"3","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0022510X24002818","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CLINICAL NEUROLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background
The presence of inflammatory changes in the cerebrospinal fluid (CSF), including immunoglobulin intrathecal synthesis (IS), can support the diagnosis of autoimmune encephalitis (AE) and allow prompt treatment. The main aim of our study was to calculate the Kappa index as a marker of IS, in patients with AE.
Methods
Charts of patients undergoing a diagnostic work-up for suspected AE between 2009 and 2023 were reviewed and the Graus criteria applied. CSF and serum kappa free light chains were determined using the Freelite assay (The Binding Site Group) and the turbidimetric Optilite analyzer.
Results
We identified 34 patients with “definite” AE (9 anti-NMDAR AE and 25 limbic AE) and nine patients with “possible” AE. Five patients (15%) with definite AE had pleocytosis and twelve (34%) showed CSF-restricted oligoclonal bands (OCB) at isoelectric focusing. The Kappa index was >6 in 29.4% and > 3 in 50% of the definite AE patients. It was elevated (>3) in 36.4% of patients with definite AE who resulted negative to OCB testing and was the only altered parameter suggestive of an ongoing inflammatory process in the CNS in three definite AE patients with otherwise normal CSF findings (i.e. normal cell count and protein levels, no OCBs). In the possible AE group, one patient had a Kappa index >3 in the absence of OCB.
Conclusions
The Kappa index could be useful, as a more sensitive marker of IS and as a supportive marker of neuroinflammation, in the diagnostic work-up of suspected AE.
期刊介绍:
The Journal of the Neurological Sciences provides a medium for the prompt publication of original articles in neurology and neuroscience from around the world. JNS places special emphasis on articles that: 1) provide guidance to clinicians around the world (Best Practices, Global Neurology); 2) report cutting-edge science related to neurology (Basic and Translational Sciences); 3) educate readers about relevant and practical clinical outcomes in neurology (Outcomes Research); and 4) summarize or editorialize the current state of the literature (Reviews, Commentaries, and Editorials).
JNS accepts most types of manuscripts for consideration including original research papers, short communications, reviews, book reviews, letters to the Editor, opinions and editorials. Topics considered will be from neurology-related fields that are of interest to practicing physicians around the world. Examples include neuromuscular diseases, demyelination, atrophies, dementia, neoplasms, infections, epilepsies, disturbances of consciousness, stroke and cerebral circulation, growth and development, plasticity and intermediary metabolism.