Diagnostic Yield and Sensitivity of Repetitive Nerve Stimulation at Different Frequencies in the Evaluation of Myasthenia Gravis
Gaber, M., Korany, S., Hosny, H., Masoud, M., Sabry, R. (2025). Diagnostic Yield and Sensitivity of Repetitive Nerve Stimulation at Different Frequencies in the Evaluation of Myasthenia Gravis. EKB Journal Management System, 6(4), 24-41. doi: 10.21608/ejmr.2025.396295.1847
Manal M Gaber; Safaa Gamal Korany; Hanan Hosny; Mohammed Mabrouk Masoud; Reem M Sabry. "Diagnostic Yield and Sensitivity of Repetitive Nerve Stimulation at Different Frequencies in the Evaluation of Myasthenia Gravis". EKB Journal Management System, 6, 4, 2025, 24-41. doi: 10.21608/ejmr.2025.396295.1847
Gaber, M., Korany, S., Hosny, H., Masoud, M., Sabry, R. (2025). 'Diagnostic Yield and Sensitivity of Repetitive Nerve Stimulation at Different Frequencies in the Evaluation of Myasthenia Gravis', EKB Journal Management System, 6(4), pp. 24-41. doi: 10.21608/ejmr.2025.396295.1847
Gaber, M., Korany, S., Hosny, H., Masoud, M., Sabry, R. Diagnostic Yield and Sensitivity of Repetitive Nerve Stimulation at Different Frequencies in the Evaluation of Myasthenia Gravis. EKB Journal Management System, 2025; 6(4): 24-41. doi: 10.21608/ejmr.2025.396295.1847

Diagnostic Yield and Sensitivity of Repetitive Nerve Stimulation at Different Frequencies in the Evaluation of Myasthenia Gravis

Egyptian Journal of Medical Research
Volume 6, Issue 4, October 2025, Pages 24-41    PDF (374.13 K)
Document Type: Original Article
DOI: 10.21608/ejmr.2025.396295.1847
Authors
Manal M Gaber1; Safaa Gamal Korany* 1; Hanan Hosny1; Mohammed Mabrouk Masoud2; Reem M Sabry1
1Department of clinical Neurophysiology, Neuro-Diagnostic and Research Center, Faculty of Medicine, Beni-Suef University, Egypt
2Department of Neurology, Faculty of Medicine, Beni-Suef University, Egypt
Abstract
Background: Myasthenia gravis (MG) is an autoimmune disorder known by fluctuating muscle weakness due to impaired neuromuscular transmission. A decremental response on repetitive nerve stimulation (RNS) represents the electrical correlate of clinical muscle fatigue and weakness in myasthenic patients. While single-fiber electromyography (SFEMG) remains the most sensitive diagnostic test, it is technically demanding and not always available. RNS is a more accessible tool, though its sensitivity can vary depending on stimulation parameters. Aim: This study aimed to assess the diagnostic sensitivity of high-frequency (10 Hz) RNS compared to the conventional 3 Hz protocol in patients with myasthenia gravis. Methods: A case-control study was conducted on 45 patients with clinically confirmed MG and 45 age and sex-matched healthy controls. Both groups underwent low-frequency (3 Hz) and high-frequency (10 Hz) RNS after withholding anticholinesterase medication for (10-12) hours. Recordings from the abductor digiti minimi, trapezius, and nasalis muscles were analyzed for decremental responses in both amplitude and area. Results: MG patients showed significant decremental responses at both frequencies (p < 0.005). High-frequency RNS demonstrated higher sensitivity in detecting neuromuscular transmission defects, particularly in amplitude and area decrements. Conclusion: High-frequency RNS enhances the detection of neuromuscular transmission abnormalities in myasthenia gravis. Its improved sensitivity and ease of application make it a valuable addition to the diagnostic workup, especially when SFEMG is unavailable or not feasible.
Keywords
Myasthenia Gravis; Slow Repetitive Nerve Stimulation, Fast Repetitive Nerve Stimulation
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