Lambert-Eaton myasthenia syndrome: specified description of a response pattern to low-frequency repetitive nerve stimulation. (August 2020)

• Record Type: Journal Article
• Authors: Zhou, Xiajun; Wang, Ze; Zhu, Ying; Zhu, Desheng; Xie, Chong; Guan, Yangtai
• Is Part Of: Journal of electromyography and kinesiology. Volume 53(2020)
• Publication Date: 2020-08
• Subjects: Lambert-Eaton myasthenia syndrome -- Repetitive nerve stimulation -- Myasthenia gravis -- Low-frequency decrement -- Neuromuscular disorder -- Electrophysiology; Electromyography -- Periodicals; Kinesiology -- Periodicals; Electromyography -- Periodicals; Movement -- physiology -- Periodicals; Muscles -- physiology -- Periodicals; Électromyographie -- Périodiques; Cinésiologie -- Périodiques; Electromyography; Kinesiology; Electronic journals; Periodicals; 616.740757
• DOI: 10.1016/j.jelekin.2020.102437
• Languages: English
• ISSNs: 1050-6411

Abstract

Highlights: We suggest a more precise response pattern to low-frequency stimulation in LEMS. A delayed nadir with a mild recovery was observed in low-frequency stimulation. The nadir position was highly efficient in differentiation. Abstract: Objective: We aimed to specify and quantify the characteristics of the decrement in low-frequency repetitive nerve stimulation response in Lambert-Eaton myasthenia syndrome (LEMS) and compare it to those of myasthenia gravis (MG). Patients and Methods: We retrospectively reviewed 18 patients with LEMS and 24 patients with MG. Ten consecutive stimulations were applied at 3 Hz to the abductor pollicis brevis. We determined the position of the smallest wave in the stimulation sequence, and we calculated the decrement and recovery. Results: The median sequential order of the minimum wave was 8 in the LEMS group and 5 in the MG group (p < 0.001). The median decrement in the LEMS group was 36.7%, while that in the MG group was 21.0% (p = 0.047). The recovery percentage was 1.4% in the LEMS group and 3.5% in the MG group (p = 0.001). The area under the curve for the sequential order of the minimum wave was 0.90, and the reciprocal optimum cut-off point was 6.5. Conclusions: We elucidated a pattern with a delayed nadir and subsequent poor recovery, featuring a low-frequency decrement; furthermore, we determined the most likely sequential order of the minimum wave in patients with LEMS, and the indicator was useful for differentiation.