Children with spastic cerebral palsy (CP) are characterized by altered muscle growth, secondary to the pathological neural input to the muscular system, caused by the primary brain lesion. As a result, their medial gastrocnemius is commonly affected and is characterized by altered macro and microscopic muscular alterations. At the macroscopic level, the muscle volume (MV), anatomical cross-sectional area of the muscle belly (Belly-CSA), muscle belly length (ML), and the intrinsic muscle quality are reduced. At the microscopic level, the cross-sectional area of the fiber (Fiber-CSA) is characterized by an increased within-patient variability (coefficient of variation (CV)), the fiber type proportion is altered and capillarization is reduced. However, the relations between the muscular alterations at the macro- and microscopic level are not yet known. Therefore, this cross-sectional study integrated macro- and microscopic parameters of the medial gastrocnemius in one cohort of young ambulant children with CP and age-matched TD children, and explored how deficits in macroscopic muscle size are associated with alterations at the microscopic level. A group of 46 children with CP (median age 5.4 (3.3) years) and a control group of 34 TD children (median age 6.3 (3.4) years), who had data on microscopic muscular properties (defined through the histological analyses of muscle biopsies), as well as macroscopic muscle properties (defined by 3D freehand ultrasound) were included. We defined Pearson or Spearman correlations, depending on the data distribution. The macroscopic muscle size parameters (MV, Belly-CSA, ML) showed significant moderate correlations (0.504-0.592) with the microscopic average Fiber-CSA in TD and CP. To eliminate the common effect of anthropometric growth at the macro- as well as microscopic level, the data were expressed as deficits (i.e. z-scores from normative centile curves or means) or were normalized to body size parameters. A significant but low correlation was found between the z-scores of MV with the z-scores of the Fiber-CSA (r=0.420, p=0.006). The normalized muscle parameters also showed only low correlations between the macro- and microscopic muscle size parameters, namely between Belly-CSA and Fiber-CSA, both in the TD (r=0.408, p=0.023) and the CP (ρ=0.329, p=0.041) group. Explorations between macroscopic muscle parameters and other microscopic muscle parameters (capillary density, capillary to fiber ratio, and fiber type proportion) revealed no or only low correlations. These results highlighted the complexity of the interacting network of intrinsic muscle structures, with mainly low associations between the macro- and microstructural level, and it remains unclear how alterations in microscopic muscle structures contribute to the macroscopic muscle size deficits in children with CP.

中文翻译：

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痉挛性脑瘫患儿腓肠肌内侧宏观与微观内在肌改变的关系

痉挛性脑瘫 (CP) 儿童的特点是肌肉生长改变，继发于原发性脑损伤引起的肌肉系统病理性神经输入。因此，他们的腓肠肌内侧通常受到影响，并以宏观和微观肌肉改变为特征。在宏观层面上，肌肉体积（MV）、肌腹解剖横截面积（Belly-CSA）、肌腹长度（ML）和内在肌肉质量减少。在微观层面上，纤维（Fiber-CSA）横截面积的特点是患者体内变异性（变异系数（CV））增加，纤维类型比例发生改变，毛细血管化减少。然而，宏观和微观层面的肌肉变化之间的关系尚不清楚。因此，这项横断面研究整合了一组患有 CP 的年轻行走儿童和年龄匹配的 TD 儿童的腓肠肌内侧的宏观和微观参数，并探讨了宏观肌肉大小的缺陷如何与微观水平的变化相关。一组 46 名 CP 儿童（中位年龄 5.4 (3.3) 岁）和一组 34 名 TD 儿童（中位年龄 6.3 (3.4) 岁），他们拥有微观肌肉特性的数据（通过肌肉活检的组织学分析定义） ）以及宏观肌肉特性（由 3D 徒手超声定义）也包括在内。我们根据数据分布定义了 Pearson 或 Spearman 相关性。宏观肌肉尺寸参数（MV、Belly-CSA、ML）与 TD 和 CP 中的微观平均 Fiber-CSA 显示出显着的中度相关性（0.504-0.592）。为了消除宏观和微观层面上人体测量生长的共同影响，数据被表示为缺陷（即来自标准百分位曲线或平均值的z分数）或被标准化为身体尺寸参数。 MV 的 z 分数与 Fiber-CSA 的 z 分数之间存在显着但较低的相关性（r=0.420，p=0.006）。归一化的肌肉参数还显示，宏观和微观肌肉尺寸参数之间的相关性较低，即 Belly-CSA 和 Fiber-CSA 之间的相关性较低，两者在 TD（r=0.408，p=0.023）和 CP（ρ=0.329， p=0.041）组。宏观肌肉参数和其他微观肌肉参数（毛细血管密度、毛细血管与纤维比率和纤维类型比例）之间的探索显示没有或只有很低的相关性。这些结果凸显了内在肌肉结构相互作用网络的复杂性，宏观和微观结构水平之间的关联性较低，目前尚不清楚微观肌肉结构的改变如何导致脑瘫儿童的宏观肌肉尺寸缺陷。