The prognostic value of diagnostic tools in patients with seropositive myasthenia gravis: a retrospective study of 31 cases
DOI:
https://doi.org/10.26641/2307-0404.2021.3.241941Ключевые слова:
seropositive myasthenia gravis, decrement test, electromyography of a single muscle fiberАннотация
To confirm the diagnosis of myasthenia gravis (MG), in addition to clinical observation of the muscle weakness dynamics, pharmacological and functional tests, Computed tomography/Magnetic resonance imaging (CT/MRI) of the mediastinum, detection of antibodies to acetylcholine receptors (AChR) and to muscle specific tyrosine kinase (MuSK)/; electrophysiological tests are used: rhythmic nerve stimulation (RNS)/decrement test and electromyography of a single muscle fiber (single-fiber EMG (SF-EMG)/jitter). The aim of our study is to determine the possible relationship between the level of antibodies to AChR and the decrement test value, to verify a correlation between SF-EMG and the severity of MG seropositive to AChR. To evaluate the effectiveness of pathogenetic treatment and prediction of the duration of remission according to the results of the study. A total of 31 patients with myasthenia gravis seropositive to AChR were examined, among whom there were 19 (61.3%) women aged 19 to 74 years. The pattern of muscle weakness was evaluated by a score of the International Clinical Classification of Severity of Myasthenia gravis scale (MGFA). The presence of respiratory failure and its degree was assessed by spirography. The number of antibodies to AChR was determined using enzyme-linked immunosorbent assay (ELISA). The criteria for inclusion in the study were the confirmed diagnosis of seropositive myasthenia gravis with an AChR antibody level of more than 0.5 nmol/L. All patients underwent electrophysiological studies. Patients were examined three times: 1) at the time of visiting the doctor (in the hospital or on an outpatient basis); 2) in 16 and 3) in 24 weeks from the start of the study. Depending on the clinical condition of the patients the following treatment was prescribed: pyridostigmine, methylprednisolone, azathioprine. Statistical analyses were performed using the statistical computing environment R (R Core Team). In the dynamics of observation, a decrease in the level of antibodies to AChR and an improvement in the condition of patients according to the MGFA classification were generally observed but no correlation was found between the severity of MG and the level of antibodies to AChR during the first visit (Kruskal-Wallis test: H (4, N=31)=2.23 p=0.69); during the second visit (Kruskal-Wallis test: H (5, N=31)=9.44 p=0.09), as well as during the third visit (Kruskal-Wallis test: H (2, N=30)=2.74 p=0.25). A correlation was found between the concentration of antibodies to AChR and a thymectomy in the clinical history (Kruskal-Wallistest: H (1, N=7)=3.153752 p=0.07): over time, the level of antibodies decreased. Decrement test deviations were detected in 23 (74.2%) of the 31 patients, SF-EMG – in 20 (95%) of 21 patients. Abnormal jitter was recorded in 100% of cases with a generalized form of myasthenia gravis. During all three visits, a correlation was determined between the highest decrement test of symptomatic muscle and MG severity according to MGFA (r=0.39; p=0.042), (r=0.35; p=0.048), (r=0.41; p=0.039); and also between the jitter value and MG severity (r=0.54; p=0.032) (r=0.35; p=0.048), (r=0.61; p=0.034 respectively). Analysis of the contingency tables using the exact Fisher test provided information on the best method of treating patients. We consider that the most effective prognostic test that may affect the choice of further treatment is SF-EMG. However, due to the difficulties of using this method in routine practice, rhythmic nerve stimulation (RNS) test in clinically weak muscles should be recommended. It is not recommended to monitor antibodies to AChR in order to predict the course of the disease, it is better to use this test only for the diagnosis of seropositive myasthenia gravis.
Библиографические ссылки
Yaremchuk-Kachmaryk I, et al. [Internal di¬seases: textbook. based on the principles of evidence-based medicine 2018/19]. Krakow: Practice. med.; 2018. p. 1632. Ukrainian.
Yan M, et al. Agrin and LRP4 antibodies as new biomarkers of myasthenia gravis. Annals of the New York Academy of Sciences. 2018;1413(1):126-35. doi: https://doi.org/10.1111/nyas.13573
Bentar M, Hammad M, Doss-Riney H. Concen¬tric-needle single-fiber electromyography for the diagno¬sis of myasthenia gravis. Muscule Nerve. 2006;34(2):163-8. doi: https://doi.org/10.1002/mus.20568
Chen YP, Wang W, Wei DN. Clinical value of low-freguency repetitive nerve stimulation in myasthenia gravis. Zhonghua Yi Xue Za Zhi. 2011;91:1178-80. doi: https://doi.org/10.3760/cma.j.issn.0376-2491.2011.17.007
Farrugio ME, et al. Correlating extent of neuro¬muscular instability with acetylcholine receptor antibodies. Muscle Nerve. 2009;39:489-93. doi: https://doi.org/10.1002/mus.21156
Engel AG. Myasthenia gravis and myasthenia discorders. Second ed. New York: Oxford University Press; 2014. p. 304.
Koneczny I, Herbst R. Myasthenia gravis: patho¬genic effects of autoantibody on neuromuscular archi¬tecture. Cells. 2019;8(7):671. doi: https://doi.org/10.3390/cells8070671
Sussman J, et al. Measthenia gravis: association of British neurologists management guidelines. Pract neurol. 2015;15(3):199-206. doi: https://doi.org/10.1136/practneurol-2015-001126
Gilhus NE, et al. Myasthenia gravis-autoantibody characteristics and their implication for therapy. Nat Rev Neurology. 2016;12:259-68. doi: https://doi.org/10.1038/nrneurol.2016.44
Jaretzki AIII, et al. Myasthenia gravis: recom¬mendation for clinical research standarts. The annals of thoracic Surgery. 2000;70(1):327-34. doi: https://doi.org/10.1212/WNL.55.1.16
Padula L. Reliability of SFEM6 in diagnosing myasthenia gravis: sensitivity and specificity calculated on 100 prospective cases. Clinical neurophysiology. 2014;125(6):1270-3. doi: https://doi.org/10.1016/j.clinph.2013.11.005
R Core Team RR. A language and environment for statistical computing. R Foundation for statistical computing. [Internet]. 2018. Available from: https://www.r-project.org/
Sanders DB. Does change in acetylcholine recep¬tor antibody level correlate with clinical change in myasthenia gravis? Muscle Nerve. 2014;49(14):483-6. doi: https://doi.org/10.1002/mus.23944
Sanders D. Guidelines for single fiber EMG. Clinical Neurophysiology. 2019;130(8):1417-39. doi: https://doi.org/10.1016/j.clinph.2019.04.005
Sanders DB, Wolfe GI, Benatar M. International consensus guidance for management of my¬asthenia gravis: executive summery. Neurology. 2016;87(4):419-25. doi: https://doi.org/10.1212/WNL.0000000000002790
Baruca M, et al. Single fiber EMG as prognostic tool in myastnenia gravis. Muscle Nerve. 2016;54:1034-40. doi: https://doi.org/10.1002/mus.25174
Wang WW, Hao HJ, Gao F. Detection of multiple antibodies in myasthenia gravis and its clinical significance. Chinese Medical Journal. 2010;123(18):2555-158. doi: https://doi.org/10.3760/cma.j.issn.0366-6999.2010.18.011
Загрузки
Опубликован
Как цитировать
Выпуск
Раздел
Лицензия
Copyright (c) 2021 Medicni perspektivi (Medical perspectives)
![Лицензия Creative Commons](http://i.creativecommons.org/l/by/4.0/88x31.png)
Это произведение доступно по лицензии Creative Commons «Attribution» («Атрибуция») 4.0 Всемирная.
Submitting manuscript to the journal "Medicni perspektivi" the author(s) agree with transferring copyright from the author(s) to publisher (including photos, figures, tables, etc.) editor, reproducing materials of the manuscript in the journal, Internet, translation into other languages, export and import of the issue with the author’s article, spreading without limitation of their period of validity both on the territory of Ukraine and other countries. This and other mutual duties of the author and all co-authors separately and editorial board are secured by written agreement by special form to use the article, the sample of which is presented on the site.
Author signs a written agreement and sends it to Editorial Board simultaneously with submission of the manuscript.