对斜角肌阻滞(SMB)的阳性反应是诊断胸廓出口综合征的重要指标。利多卡因注射液是临床上常用的SMB,尽管有一些误诊的病例。肉毒杆菌毒素A(BTX-A)是SMB治疗药物之一,但是否也适用于SMB诊断是有争议的。为了评估这两种药物的肌肉阻滞效率,反复记录大鼠胫骨前肌的收缩强度。发现在安全剂量下,2%利多卡因在40μL时表现最好,但它仍然表现出不能令人满意的部分阻塞效率。此外,利多卡因注射联合肾上腺素或地塞米松或多个部位注射均不能提高阻断效率。另一方面,注射3、6和12U/kgBTX-A均显示几乎完全的肌肉阻滞。步态分析显示拮抗腓肠肌,负责鞋跟上升,在12U/kgBTX-A组中因非特异性阻塞而瘫痪,但不在3U/kg或6U/kgBTX-A组中。裂解的突触体相关蛋白25(c-SNAP25)染色以测试BTX-A的运输,并且在6和12U/kg组的外周肌肉中也观察到。C-SNAP25,然而,在BTX-A给药后在脊髓中几乎检测不到。因此,我们的结果表明,低剂量BTX-A可能是诊断胸廓出口综合征的SMB的一个有前景的选择.意义声明:肌肉阻滞对于诊断和治疗胸腔出口综合征很重要,通常使用利多卡因进行。然而,有时出现误诊。这里,我们发现肌内注射最佳剂量的利多卡因只能部分阻断大鼠的肌肉收缩,而低剂量的肉毒杆菌毒素,几乎不用于诊断模块,显示几乎完全阻滞而不影响中枢神经系统。这项研究表明,在临床实践中,肉毒杆菌毒素可能比利多卡因更适合用于肌肉阻滞。
A positive response to scalene muscle block (SMB) is an important indication for the diagnosis of thoracic outlet syndrome. Lidocaine injection is commonly used in clinical practice in SMB, although there have been some cases of misdiagnosis. Botulinum toxin A (BTX-A) is one of the therapeutic agents in SMB, but whether it is also indicated for SMB diagnosis is controversial. To evaluate the muscle block efficiency of these two drugs, the contraction strength was repeatedly recorded on tibialis anterior muscle in rats. It was found that at a safe dosage, 2% lidocaine performed best at 40 μL, but it still exhibits an unsatisfactory partial blocking efficiency. Moreover, neither lidocaine injection in combination with epinephrine or dexamethasone nor multiple locations injection could improve the blocking efficiency. On the other hand, injections of 3, 6, and 12 U/kg BTX-A all showed almost complete muscle block. Gait analysis showed that antagonistic gastrocnemius muscle, responsible for heel rising, was paralyzed for nonspecific blockage in the 12 U/kg BTX-A group, but not in the 3 U/kg or 6 U/kg BTX-A group. Cleaved synaptosomal associated protein 25 (c-SNAP 25) was stained to test the transportation of BTX-A, and was additionally observed in the peripheral muscles in 6 and 12 U/kg groups. c-SNAP 25, however, was barely detectable in the spinal cord after BTX-A administration. Therefore, our results suggest that low dosage of BTX-A may be a promising option for the diagnostic SMB of thoracic outlet syndrome. SIGNIFICANCE STATEMENT: Muscle block is important for the diagnosis and treatment of thoracic outlet syndrome and commonly performed with lidocaine. However, misdiagnosis was observed sometimes. Here, we found that intramuscular injection of optimal dosage lidocaine only partially blocked the muscle contraction in rats, whereas low-dosage botulinum toxin, barely used in diagnostic block, showed almost complete block without affecting the central nervous system. This study suggests that botulinum toxin might be more suitable for muscle block than lidocaine in clinical practice.