Background: Nowadays, it is widely known that decremental responses in low-frequency repetitive nerve stimulation (LF-RNS) are frequently observed in patients with amyotrophic lateral sclerosis (ALS). The pathological mechanism of this phenomenon remains unknown. This study aimed to illuminate the features of RNS in Chinese patients with ALS.
Methods: Clinical and electrophysiological data of 146 probable and definite ALS patients who underwent RNS were retrospectively enrolled and analyzed. LF-RNS (3 Hz) was performed in trapezius, deltoid, abductor digiti minimi (ADM), quadriceps femoris, and tibialis anterior. High-frequency RNS (HF-RNS, 10 Hz) was performed only in ADM. The two-sample t-test and Chi-squared test were used for statistical analysis.
Results: Decremental responses to LF-RNS (≥10%) in at least one muscle were detected in 83 (56.8%) of the cases and were most commonly seen in trapezius and deltoid. The incidence of decremental response was higher in patients with upper limb onset. Incremental responses to HF-RNS (≥60%) in ADM were observed in 6 (5.6%) of the cases. In 106 muscles with decremental response, 62 (57.4%) muscles had a continuous decremental pattern, more than a U-shape pattern (37 cases, 34.3%). Nineteen cases showed definite decrements in LF-RNS tests in trapezius, while no abnormalities were found in the electromyography and neurological examination of the sternocleidomastoid muscle, supplied by the accessory nerve as well.
Conclusions: Decremental responses in the RNS are commonly observed in ALS patients. The findings regarding the trapezius indicated that some ALS onsets could be initiated by a "dying back" process, with destruction of neuromuscular junctions (NMJs) before motor neurons. Incremental responses in the ADM implied damage of the NMJs involved both the post and presynaptic membranes.
肌萎缩侧索硬化患者的重复神经刺激的研究摘要背景：肌萎缩侧索硬化患者中低频神经刺激递减现象较常见。至今这一现象出现的原因仍存在争议。本研究旨在总结中国肌萎缩侧索硬化（ALS）患者重复神经刺激（RNS）的特点。 方法：研究收集了146例拟诊级别以上的ALS患者的临床资料及针极肌电图和重复神经刺激的数据，进行回顾性研究。副神经、腋神经、尺神经、股神经、腓总神经行低频神经刺激（3Hz），尺神经行高频神经刺激（10Hz）。统计学分析采用t检验和卡方检验。 结果：83（56.8%）例患者至少一根神经出现低频刺激递减（≥10%），其中以副神经和腋神经最为常见。在上肢起病的患者中低频递减阳性率更高。6（5.6%）例患者尺神经高频刺激出现递增（≥60%）。在106根低频刺激递减的神经中，62（57.4%）根神经RNS图像呈现持续递减的波型，37（34.3%）根神经呈现U型回升的波型。19例患者副神经低频重复刺激≥10%，副神经支配的胸锁乳突肌针极肌电图及肌力检查正常。 结论：中国ALS患者中RNS异常现象较常见；ALS患者中可能存在逆向死亡的发病过程，在神经元丢失之前神经肌肉接头已经出现功能障碍；ALS患者的神经肌肉接头损害可能同时波及整个突触包括前膜和后膜。.
Keywords: Amyotrophic Lateral Sclerosis; Decremental Response; Dying Back; Repetitive Nerve Stimulation.