Kurtkaya Koçak Özlem, Bora Tokçaer Ayşe
Department of Neurology, Section of Clinical Neurophysiology, Faculty of Medicine, Gazi University, Ankara, Turkey.
Department of Neurology, Section of Clinical Neurophysiology, Ankara Bilkent City Hospital, Ankara, Turkey.
Neurol Sci. 2025 May;46(5):2159-2165. doi: 10.1007/s10072-024-07947-1. Epub 2024 Dec 19.
There is growing evidence that botulinum neurotoxin (BoNT) can mediate changes at the central level through peripheral mechanisms, leading to alterations in central sensorimotor integration. However, the effect of BoNT on brainstem excitability in patients with hemifacial spasm(HFS) is not yet fully understood, and its long-term effects remain unknown.
This study aims to investigate the impact of BoNT on the excitability of the facial nucleus in patients with idiopathic HFS.
In order to evaluate the peripheral effect of the toxin, the amplitude of compound muscle action potential (CMAP) of orbicularis oculi (OOc) muscles was evaluated. To investigate the effects of locally injected BoNT on the brainstem, particularly the facial motor nucleus, we evaluated the amplitude and latency of the blink reflex (BR), the synkinetic responses (SR) and the ratio of contralateral R2 (cR2) amplitude of BR/CMAP amplitude in 16 patients with HFS. These measurements were performed before and after the 1 and 4 month BoNT injection.
Following BoNT therapy there was a significant amplitude reduction and latency prolongation of R1, iR2, cR2 and SR elicited by the stimulation of the side of BoNT injection. The mean CMAP amplitude of OOc muscle was significantly lower after BoNT injection. The ratio of cR2 amplitude/CMAP amplitude of OOc showed a significant decline after BoNT therapy.
Our study demonstrated that BoNT suppresses the excitability of facial motor neurons in idiopathic HFS via the trigeminal afferent mechanism. These effects persisted during the fourth month, despite BoNT's diminished activity.
越来越多的证据表明，肉毒杆菌神经毒素（BoNT）可通过外周机制介导中枢水平的变化，导致中枢感觉运动整合的改变。然而，BoNT对偏侧面肌痉挛（HFS）患者脑干兴奋性的影响尚未完全明确，其长期影响仍不清楚。
本研究旨在探讨BoNT对特发性HFS患者面神经核兴奋性的影响。
为了评估毒素的外周效应，评估眼轮匝肌（OOc）复合肌肉动作电位（CMAP）的幅度。为了研究局部注射BoNT对脑干，特别是面神经运动核的影响，我们评估了16例HFS患者的眨眼反射（BR）幅度和潜伏期以及联带运动反应（SR），并计算BR/CMAP幅度的对侧R2（cR2）幅度比值。这些测量在BoNT注射前以及注射后1个月和4个月进行。
BoNT治疗后，注射BoNT一侧刺激诱发的R1、iR2、cR2和SR的幅度显著降低，潜伏期延长。BoNT注射后，OOc肌的平均CMAP幅度显著降低。BoNT治疗后，OOc肌的cR2幅度/CMAP幅度比值显著下降。
我们的研究表明，BoNT通过三叉神经传入机制抑制特发性HFS患者面神经运动神经元的兴奋性。尽管BoNT活性降低，但这些效应在第四个月仍持续存在。
