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Nagaoka A, Tsujino A, Shiraishi H, Kanamoto T, Shima T, Yoshimura S, Miyazaki T, Tateishi Y, Tsujihata M, Motomura M, Maxwell S, Higuchi O, Beeson D, Vincent A. Motor end-plate analysis to diagnose immune-mediated myasthenia gravis in seronegative patients. J Neurol Sci 2022; 443:120494. [PMID: 36403297 DOI: 10.1016/j.jns.2022.120494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 11/08/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022]
Abstract
This study aimed to evaluate the diagnostic usefulness of motor end-plate (MEP) analysis along with clustered acetylcholine receptor (AChR) antibody (Ab) assays in patients with myasthenia-like symptoms but negative routine AChR and muscle-specific kinase (MuSK) Ab tests. MEP analysis of muscle biopsies of the biceps brachii was performed in 20 patients to try to differentiate between those with or without immune-mediated myasthenia gravis (MG). Using a quantitative method, complement C3 deposition and AChR densities in MEPs were examined. Independently, cell-based assays were used to detect serum clustered-AChR Abs. Only five of 20 patients had complement deposition at MEPs; four of these patients had reduced AChR densities similar to those in patients with typical AChR Ab positive MG, and distinct from those in the remaining 15 patients. Two of the four serum samples from these patients had clustered-AChR Abs. All complement-positive patients were considered as having immune-mediated MG and improved with appropriate treatments; although one patient presented with MG 3 years later, the remaining patients had other diagnoses during over 10 years of follow-up. These results suggest the usefulness of MEP analysis of muscle biopsies in diagnosing immune-mediated MG in seronegative patients with myasthenia-like symptoms but, due to the invasiveness of the muscle biopsy procedure, clustered AChR Abs should, if possible, be tested first.
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Affiliation(s)
- Atsushi Nagaoka
- Department of Clinical Neuroscience, Unit of Clinical Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki City, Japan.
| | - Akira Tsujino
- Department of Clinical Neuroscience, Unit of Clinical Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki City, Japan.
| | - Hirokazu Shiraishi
- Department of Neurology and Strokology, Nagasaki University Hospital, Nagasaki City, Japan
| | - Tadashi Kanamoto
- Department of Neurology and Strokology, Nagasaki University Hospital, Nagasaki City, Japan
| | - Tomoaki Shima
- Department of Neurology and Strokology, Nagasaki University Hospital, Nagasaki City, Japan.
| | - Shunsuke Yoshimura
- Department of Neurology and Strokology, Nagasaki University Hospital, Nagasaki City, Japan.
| | - Teiichiro Miyazaki
- Department of Neurology and Strokology, Nagasaki University Hospital, Nagasaki City, Japan.
| | - Yohei Tateishi
- Department of Neurology and Strokology, Nagasaki University Hospital, Nagasaki City, Japan.
| | | | - Masakatsu Motomura
- Medical Electronic Course, Nagasaki Institute of Applied Science, Nagasaki City, Japan.
| | - Susan Maxwell
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK.
| | - Osamu Higuchi
- Department of Neurology, Nagasaki Kawatana Medical Center, Nagasaki, Japan.
| | - David Beeson
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK.
| | - Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK.
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