VALUATION OF THE RESPONSE TO REPEATED NERVE STIMULATION TEST IN PATIENTS WITH OCULAR MYASTHENIA GRAVIS

Triệu Thị Tạo1, Nguyễn Văn Tuận2,
1 Hanoi Medical University
2 National Mental Health Institute, Bach Mai Hospital

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Abstract

Aim: To evaluate the response of consecutively repeated nerve stimulation tests in patients with ocular myasthenia gravis. Objects and methods:  43 patients with ocular myasthenia gravis had positive anti-acetylcholine antibody or positive neostigmine test. Results: The average age of onset of patients was 39.2 ± 17.7 (ocular myasthenia gravis), 43.1 ± 13 (generalized myasthenia gravis), the time since the onset of ocular myasthenia gravis the conversion to the whole body was 18.9 ± 59.7 months. The repetitive nerve stimulation test was positive in 28 patients (65.1%), the positive rate in ocular myasthenia gravis 30.2%, sensitivity 30.8%, sensitivity 80% for the generalized myasthenia gravis group. The sensitivity of each muscle also varies according to muscle group: trapezius muscle (61.5%), ocular muscle (53.8%), abductor pollicis brevis (30.8%), abductor digiti minimi muscle (38.5%), and sensitivities of repetitive nerve stimulation were significantly higher in the generalized myasthenia gravis according to subgroup: 90%, 86.7%, 80%, 66.7%. Repetitive nerve stimulation is associated with clinical severity according to Osserman's classification (P = 0.001). Conclusions: Repetitive nerve stimulation test is a simple and convenient test that can help diagnose myasthenia gravis faster and can detect subclinical muscle weakness.

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References

1. Smith S V, & Lee A G. (2017). Update on Ocular Myasthenia Gravis. Neurol Clin, 35(1), 115-123. doi:10.1016/j.ncl.2016.08.008
2. Osserman KE. (1967). Ocular Myasthenia Gravis. Invest Ophthalmol Vis Sci, 6(3), 277-287.
3. Gilhus N E, & Verschuuren J J. (2015). Myasthenia gravis: subgroup classification and therapeutic strategies. Lancet Neurol, 14(10), 1023-1036. doi:10.1016/S1474-4422(15)00145-3
4. Vincent A, & Newsom Davis J. (1980). Anti-acetylcholine receptor antibodies. J Neurol Neurosurg Psychiatry, 43(7), 590-600. doi:10.1136/jnnp.43.7.590
5. Thanvi B R, & Lo T C. (2004). Update on myasthenia gravis. Postgrad Med J, 80(950), 690-700. doi:10.1136/pgmj.2004.018903
6. Nguyễn Hữu Công. (2013). Chẩn đoán điện và ứng dụng lâm sàng: Nhà xuất bản Đại học quốc gia thành phố Hồ Chí Minh.
7. Kim K H, Kim S W, & Shin H Y. (2021). Initial Repetitive Nerve Stimulation Test Predicts Conversion of Ocular Myasthenia Gravis to Generalized Myasthenia Gravis. J Clin Neurol, 17(2), 265-272. doi:10.3988/jcn.2021.17.2.265
8. Oh S J, Jeong D, Lee I, et al. (2019). Repetitive nerve stimulation test in myasthenic crisis. Muscle Nerve, 59(5), 544-548. doi:10.1002/mus.26390
9. Witoonpanich R, Barakul S, & Dejthevaporn C. (2006). Relative fatigability of muscles in response to repetitive nerve stimulation in myasthenia gravis. J Med Assoc Thai, 89(12), 2047-2049.
10. Jing F, Cui F, Chen Z, et al. (2015). Clinical and Electrophysiological Markers in Myasthenia Gravis Patients. Eur Neurol, 74(1-2), 22-27. doi:10.1159/000431284