Free light chains kappa can differentiate between myelitis and noninflammatory myelopathy. Issue 6 (November 2020)

• Record Type: Journal Article
• Authors: Süße, Marie; Feistner, Fritz; Grothe, Matthias; Nauck, Matthias; Dressel, Alexander; Hannich, Malte Johannes
• Is Part Of: Neurology. Volume 7:Issue 6(2020)
• Publication Date: 2020-11
• Subjects: Neuroimmunology -- Periodicals; Neurology -- Periodicals; 616.8
• DOI: 10.1212/NXI.0000000000000892
• Languages: English
• ISSNs: 2332-7812

Abstract

Abstract : Objective: To test the hypothesis that the intrathecal synthesis of free light chain kappa (FLC-k) can be used as a CSF biomarker to differentiate patients with myelitis due to multiple sclerosis (MS), myelitis due to neuromyelitis optica spectrum disease (NMOSD), and noninflammatory myelopathy, we analyzed FLC-k in 26 patients with MS myelitis, 9 patients with NMOSD myelitis, and 14 patients with myelopathy. Methods: This is a retrospective monocentric cohort study. FLC-k were analyzed using the nephelometric Siemens FLC-k kit in paired samples of CSF and sera. Intrathecal fraction (IF) of FLC-k was plotted in a FLC-k quotient diagram. Results: Ninety-six percent of patients with MS myelitis had an intrathecal synthesis of FLC-k in comparison with 55.6% for NMOSD and 14.3% of patients with noninflammatory myelopathy. The locally synthesized absolute amount of FLC-k was significantly higher in patients with myelitis due to MS than in patients with NMOSD ( p = 0.038) or noninflammatory myelopathy ( p < 0.0001). The sensitivity of FLC-k synthesis to detect inflammation in patients with myelitis is 85.7%. Using a receiver operating characteristic analysis, FLC-k IF >78% can discriminate patients with myelitis due to MS and NMOSD with a sensitivity of 88.5% and a specificity of 88.9% Conclusions: With the hyperbolic reference range in quotient diagrams for FLC-k, it is possible to distinguish inflammatory myelitis from noninflammatory myelopathies. An FLC-k IF >78% can be a hint to suspect myelitis due to MS rather than NMOSD.