Mechanism of hypertonia in cerebral palsy children is dual: a neural component due to spasticity (velocity dependent) and a biomechanical component linked to soft tissue changes. Their differentiation—which might be clinically difficult—is however crucial, as only the first component will respond to anti-spastic treatments, the second to physiotherapy. Furthermore, spasticity is frequently associated with dystonia, which is a sustained hypertonic state induced by attempts at voluntary motion. Spasticity and dystonia have to be carefully distinguished as dorsal rhizotomy will not significantly influence the dystonic component. Spasticity, which by definition opposes to muscle stretching and lengthening, has two important consequences. First, the muscles tend to remain in a shortened position, which in turn results in soft tissue changes and contracture. The second is that movements are restricted. Thus, both hypertonia and lack of mobilization create a vicious circle leading to severe locomotor disability linked to irreducible musculotendinous retraction and joint ankylosis/bone deformities. These evolving consequences should be highly considered during the child’s assessment for decision-making. The hypotonic effects of lumbosacral dorsal rhizotomy, which are not only segmental on the lower limbs but also supra-segmental through the reticular formation, are finally discussed.

脑性瘫痪儿童高渗的机制是双重的：由于痉挛引起的神经成分（依赖于速度）和与软组织变化有关的生物力学成分。然而，它们的区分（可能在临床上可能很困难）至关重要，因为只有第一个成分会对抗痉挛性治疗产生反应，第二个成分对理疗产生响应。此外，痉挛常与肌张力障碍有关，肌张力障碍是由自愿运动的尝试引起的持续的高渗状态。必须仔细地区分痉挛性和肌张力障碍，因为背侧根切断术不会显着影响肌张力障碍成分。痉挛，从定义上讲与肌肉的伸展和伸长相反，具有两个重要的后果。首先，肌肉倾向于保持缩短的姿势，进而导致软组织的变化和挛缩。第二是动作受到限制。因此，高渗症和缺乏动员都造成恶性循环，导致严重的运动障碍，与无法还原的肌肉弹性收缩和关节强直/骨骼畸形有关。这些不断演变的后果应在儿童评估决策时予以高度考虑。最后讨论了腰s背侧根管切开术的低渗作用，该作用不仅在下肢呈节段性，而且在网状结构上呈超节段性。这些不断演变的后果应在儿童评估决策时予以高度考虑。最后讨论了腰s背侧根管切开术的低渗作用，该作用不仅在下肢呈节段性，而且在网状结构上呈超节段性。这些不断演变的后果应在儿童评估决策时予以高度考虑。最后讨论了腰s背侧根管切开术的低渗作用，该作用不仅在下肢呈节段性，而且在网状结构上呈超节段性。