Pain is the most common and disabling non-motor symptom in cervical dystonia (CD). Up to 88.9% of patients report pain at some point in the course of the disease. It is still a matter of debate whether CD-related pain originates only from prolonged muscle contraction. Recent data suggest that the alterations of transmission and processing of nociceptive stimuli play a crucial role in pain development. Botulinum toxin (BT) is the first-line therapy for CD. Despite fully elucidated muscle relaxant action, the antinociceptive effect of BT remains unclear and probably exceeds a simple decompression of the nerve fibers due to the reduction in muscle tone. The proposed mechanisms of the antinociceptive action of BT include inhibition of pain mediator release, inhibition of membrane sodium channels, retrograde axonal transport and impact on the other pain pathways. This article summarizes the current knowledge about the antinociceptive properties of BT and the clinical analgesic efficacy in the treatment of CD patients.

中文翻译：

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颈肌张力障碍的疼痛和肉毒杆菌毒素的镇痛作用：目前已知的是什么？

疼痛是颈肌张力障碍 (CD) 中最常见和致残的非运动症状。高达 88.9% 的患者在疾病过程中的某个时间点报告疼痛。与 CD 相关的疼痛是否仅源于长时间的肌肉收缩仍然存在争议。最近的数据表明，伤害性刺激的传递和处理的改变在疼痛发展中起着至关重要的作用。肉毒杆菌毒素 (BT) 是 CD 的一线疗法。尽管已经完全阐明了肌肉松弛作用，但 BT 的镇痛作用仍不清楚，并且可能超过由于肌肉张力降低而导致的神经纤维的简单减压。BT 的镇痛作用机制包括抑制疼痛介质释放、抑制膜钠通道、逆行轴突运输和对其他疼痛通路的影响。本文总结了目前关于BT的镇痛特性和治疗CD患者的临床镇痛效果的知识。