Background

Many children with cerebral palsy develop muscle contractures. The mechanisms of contracture are not well understood. We investigated the possibility that, because fat is stiffer than passive muscle, elevated intramuscular fat contributes to contracture. In this cross-sectional study, we compared the quantity and distribution of intramuscular fat in muscles from typically developing children and children with cerebral palsy who have contractures.

Methods

mDixon magnetic resonance images were obtained from the legs of 20 ambulant children with unilateral spastic cerebral palsy who had ankle contractures (mean age 11 SD 3 years, 13 male, mean moderate level contracture) and 20 typically developing children (mean age 11 SD 4 years, 13 male). The images were analyzed to quantify the intramuscular fat fraction of the medial gastrocnemius muscles. The amount and distribution of intramuscular fat were compared between muscles of children with cerebral palsy and typically developing children.

Findings

In typically developing children, the medial gastrocnemius muscles had a mean intramuscular fat fraction of 4.7% (SD 1.6%). In children with cerebral palsy, the mean intramuscular fat fractions in the more- and less-affected medial gastrocnemius muscle were 11.4% (8.1%) and 6.9% (3.4%) respectively. There were small but statistically significant regional differences in the distribution of intramuscular fat. There was no evidence of a relationship between intramuscular fat fraction and severity of contracture.

Interpretation

Children with cerebral palsy have higher proportions of intramuscular fat than typically developing children. There is no clear relationship between intramuscular fat fraction and dorsiflexion range of motion in children with cerebral palsy.

中文翻译：

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小儿单侧脑瘫患儿的肌内脂肪

背景

许多患有脑瘫的儿童会出现肌肉挛缩。挛缩的机制尚不清楚。我们调查了由于脂肪比被动肌肉更硬而导致的肌肉内脂肪增加导致挛缩的可能性。在这项横断面研究中，我们比较了典型发育中的儿童和患有挛缩症的脑瘫儿童的肌肉中肌肉内脂肪的数量和分布。

方法

mDixon磁共振图像是从20名患有单侧痉挛性脑瘫的踝关节挛缩（平均年龄11 SD 3岁，男性13位，平均中等水平挛缩）的20名典型发育中儿童（平均年龄11 SD 4岁）的腿部获得的，13位男性）。分析图像以量化腓肠内侧肌的肌内脂肪分数。比较了脑瘫儿童和发育中儿童的肌肉内肌内脂肪的数量和分布。

发现

在典型的发育中儿童中，腓肠肌内侧的平均肌内脂肪分数为4.7％（标准差为1.6％）。在患有脑瘫的儿童中，患内侧和外侧腓肠肌的平均肌内脂肪分数分别为11.4％（8.1％）和6.9％（3.4％）。肌内脂肪分布存在微小但具有统计学意义的区域差异。没有证据表明肌内脂肪含量与挛缩严重程度之间存在关系。

解释

脑瘫患儿的肌内脂肪比例高于正常发育的患儿。脑瘫患儿的肌内脂肪含量与背屈运动范围之间没有明确的关系。