Weidensteiner Claudia, Madoerin Philipp, Deligianni Xeni, Haas Tanja, Bieri Oliver, Akinci D'Antonoli Tugba, Bracht-Schweizer Katrin, Romkes Jacqueline, De Pieri Enrico, Santini Francesco, Rutz Erich, Brunner Reinald, Garcia Meritxell
Division of Radiological Physics, Department of Radiology, University Hospital of Basel, Basel, Switzerland.
Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland.
Front Neurol. 2021 Apr 16;12:630435. doi: 10.3389/fneur.2021.630435. eCollection 2021.
Muscles from patients with cerebral palsy (CP) are often spastic and form contractures that limit the range of motion. Injections of botulinum toxin A (BTX) into the calf muscles are an important treatment for functional equinus; however, improvement in gait function is not always achieved. BTX is also used to test muscle weakening for risk evaluation of muscle lengthening surgery. Our aim was to assess the effect of BTX over time on calf muscle properties in pediatric CP patients with MRI. Six toe-walking CP patients (mean age 11.6 years) with indication for lengthening surgery were prospectively enrolled and received BTX injections into the gastrocnemius and soleus muscles. MRI scans at 3T of the lower legs and clinical examinations were performed pre-BTX, 6 weeks (6w), and 12 weeks (12w) post-BTX. A fat-suppressed 2D multi-spin-echo sequence was used to acquire T maps and for segmentation. Fat fraction maps were calculated from 3D multi-echo Dixon images. Diffusion tensor imaging (DTI) with a 2D echo-planar imaging (EPI) sequence yielded maps of the mean apparent diffusion coefficient (ADC) and of the fractional anisotropy (FA). Hyperintense regions of interest (ROIs) on the T-weighted (Tw) images at 6w were segmented in treated muscles. Mean values of T, fat fraction, ADC, and FA were calculated in hyperintense ROIs and in reference ROIs in non-treated muscles. Hyperintensity on Tw scans and increased T (group mean ± standard deviation: 35 ± 1 ms pre-BTX, 45 ± 2 ms at 6w, and 44 ± 2 ms at 12w) were observed in all patients at the injection sites. The T increase was spatially limited to parts of the injected muscles. FA increased (0.30 ± 0.03 pre-BTX, 0.34 ± 0.02 at 6w, and 0.36 ± 0.03 at 12w) while ADC did not change in hyperintense ROIs, indicating a BTX-induced increase in extracellular space and a simultaneous decrease of muscle fiber diameter. Fat fraction showed a trend for increase at 12w. Mean values in reference ROIs remained unchanged. MRI showed limited spatial distribution of the BTX-induced effects in pediatric CP patients. It could be a promising non-invasive tool for future studies to test BTX treatment protocols.
脑瘫（CP）患者的肌肉通常会出现痉挛并形成挛缩，从而限制运动范围。向小腿肌肉注射A型肉毒杆菌毒素（BTX）是治疗功能性马蹄足的重要方法；然而，步态功能并不总能得到改善。BTX还用于测试肌肉弱化情况，以评估肌肉延长手术的风险。我们的目的是通过MRI评估BTX随时间对小儿CP患者小腿肌肉特性的影响。前瞻性纳入了6名有延长手术指征的踮足行走CP患者（平均年龄11.6岁），并向其腓肠肌和比目鱼肌注射BTX。在注射BTX前、注射后6周（6w）和12周（12w）对小腿进行3T MRI扫描并进行临床检查。使用脂肪抑制二维多自旋回波序列获取T图并进行分割。根据三维多回波狄克逊图像计算脂肪分数图。采用二维回波平面成像（EPI）序列的扩散张量成像（DTI）生成平均表观扩散系数（ADC）图和分数各向异性（FA）图。在6w时，对T加权（Tw）图像上治疗肌肉中的高信号感兴趣区域（ROI）进行分割。计算高信号ROI和未治疗肌肉中参考ROI的T、脂肪分数、ADC和FA的平均值。所有患者注射部位的Tw扫描均显示高信号，且T值升高（组均值±标准差：注射BTX前为35±1ms，6w时为45±2ms，12w时为44±2ms）。T值升高在空间上局限于注射肌肉的部分区域。在高信号ROI中，FA升高（注射BTX前为0.30±0.03，6w时为0.34±0.02，12w时为0.36±0.03），而ADC未改变，这表明BTX诱导细胞外间隙增加，同时肌纤维直径减小。脂肪分数在12w时有增加趋势。参考ROI中的平均值保持不变。MRI显示BTX诱导的效应在小儿CP患者中的空间分布有限。它可能是未来研究测试BTX治疗方案的一种有前景的非侵入性工具。
