Clinical characterization and repetitive nerve stimulation test in patients with myasthenia gravis

Pham Kieu Anh Tho, Le Dinh Tung, Nguyen Thanh Binh

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Abstract

The purpose of this study is to describe the clinical characterization and repetitive nerve stimulation test performed in 30 myasthenic patients by a descriptive research method. The research results noted: the average age was 48.57 years old, the female/male ratio was 2:1; there were 7 patients in group I (23.3%), 7 patients in group IIa (23.3%), 7 patients in group IIb (23.3%), 6 patients in group IIIa (20%), 2 patients in group IIIb (6.7%) and 1 patient in group IVa (3.3%); 73.3% of patients had positive AchRs antibodies, 20% of them have thymoma. Repetitive nerve stimulation test (RNS) was positive in 21 patients (70%), patients with affected ocular muscles only (group I) had a positive RNS test rate of 42.9%, and patients with affected limbs and truncal muscles (groups a: IIa, IIIa, IVa) had a positive RNS test rate of 64.2%, The myasthenic patients with affected respiratory and pharyngeal muscle (groups b: IIb, IIIb) had a 100% positive RNS test rate. In conclusion, there is a statistically significant association between the abnormal result on repetitive nerve stimulation test and the myasthenia gravis classification in clinical settings according to MGFA (p = 0.01) and the AchRs antibody quantitative assay (p = 0.001).

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References

1. Jaretzki AR BR, Ernstoff RM, et al. Myasthenia gravis: recommendations for clinical resreach standards, Task Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of America. Neurology. 2000; 55: 16 – 23.
2. Nils Erik Gilhus JJV. Myasthenia gravis: subgroup classifi cation and therapeutic strategies. Lancet Neurol. 2015; 14: 1023 – 1036.
3. Pasnoor M, Dimachkie MM, Farmakidis C, Barohn RJ. Diagnosis of Myasthenia Gravis. Neurologic Clinics. 2018; 36(2): 261 - 274.
4. Nils Erik Gilhus, Socrates Tzartos. Myasthenia gravis. Disease Primer. 2019; 5: 30.
5. Matthew N Meriggioli DBS. Autoimmune myasthenia gravis: emerging clinical and biological heterogeneity. Lancet Neurol. 2009; 8: 475 – 490.
6. Howard JF. Electrodiagnosis of Disorders of Neuromuscular Transmission. Physical Medicine and Rehabilitation Clinics of North America. 2013; 24(1): 169 - 192.
7. Preston DC, Shapiro BE. Neuromuscular Junction Disorders. In: Preston DC, Shapiro BE, eds. Electromyography and Neuromuscular Disorders (Third Edition). London: W.B. Saunders; 2013: 529 - 548.
8. Padua L, Caliandro P, Di Iasi G, Pazzaglia C, Ciaraffa F, Evoli A. Reliability of SFEMG in diagnosing myasthenia gravis: Sensitivity and specificity calculated on 100 prospective cases. Clinical Neurophysiology.2014; 125(6): 1270 - 1273.
9. Costa J, Evangelista T, Conceição I, Carvalho Md. Repetitive nerve stimulation in myasthenia gravis—relative sensitivity of different muscles. Clinical Neurophysiology. 2004; 115(12): 2776 - 2782.
10. Committee Aqa. Practice parameter for repetitive nerve stimulation and single fiber emg evaluation of adults with suspected myasthenia gravis or lambert–eaton myasthenic syndrome: Summary statement. Muscle Nerve. 2001; 24: 1236 – 1238.
11. Abraham A, Alabdali M, Alsulaiman A, et al. Repetitive facial nerve stimulation in myasthenia gravis 1min after muscle activation is inferior to testing a second muscle at rest. Clinical Neurophysiology. 2016; 127(10): 3294 - 3297.
12. Maarika Liik a ARP. Repetitive nerve stimulation often fails to detect abnormal decrement in acute severe generalized Myasthenia Gravis. Clinical Neurophysiology. 2016; 127: 3480 – 3484.
13. Philippe Gajdos MCT, MD. Treatment of Myasthenia Gravis Exacerbation with Intravenous Immunoglobulin. Arch Neurol. 2005; 62: 1689 - 1693.
14. Lingling Fan SM, Yongxiang Yang, Zhongjun Yan, Junchao Li & Zhuyi Li. Clinical differences of early and late-onset myasthenia gravis in 985 patients. Neurological Research. 2018; ISSN: 0161 - 6412: 1743 - 1328.
15.Erik H. Niks m, umesh a. Badrising, md,. Decremental response of the nasalis and hypothenar muscles in myasthenia gravis. Muscle Nerve.2003; 28: 236 – 238.
16. Committee Aqa. Literature review of the usefulness of repetitive nerve stimulation and single fiber emg in the electrodiagnostic evaluation of patients with suspected myasthenia gravis or lambert-eaton myasthenic syndrome. Muscle Nerve. 2001; 24: 1239 – 1247.
17. Popperud MIB, Rasmussen, Kerty. Juvenile myasthenia gravis in Norway: Clinical characteristics, treatment, and long-term outcome in a nationwide population-based cohort. Official Journal of the European Paediatric Neurology Society. 2017; 21; 707–714.