Alteration of brain viscoelasticity after shunt treatment in normal pressure hydrocephalus
Alteration of brain viscoelasticity after shunt treatment in normal pressure hydrocephalus
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DOI：
10.1007/s00234-011-0871-1
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发表时间：
2012-03-01
期刊：
影响因子：
2.8
通讯作者：
Sack, Ingolf
中科院分区：
文献类型：
--
作者：
Freimann, Florian Baptist;Streitberger, Kaspar-Josche;Sack, Ingolf
正常压力脑积水（NPH）是一种慢性神经系统疾病，发病率不断增加。NPH的症状可以通过手术植入脑室腹膜分流管引流多余的脑脊液来缓解。然而，NPH的发病机制尚未完全阐明，分流治疗的临床反应难以预测。根据目前的NPH理论，脑组织的机械特性改变似乎起着重要作用。磁共振弹性成像（MRE）是一种测量活体脑力学的独特方法，在这项研究中，应用脑MRE测试20例原发性（N = 14）和继发性（N = 6）NPH患者在分流术前后（91 +/- 16天）的脑粘弹性。根据流变弹簧模型，由复模量导出粘弹性参数。该模型提供了两个独立的参数μ和α，与脑组织的固有刚度和力学网络拓扑结构有关，与年龄匹配的对照组相比，粘弹参数μ和α分别降低了-25%和-10%（P < 0.001）。有趣的是，分流术后α增加（P < 0.001），几乎达到正常值，而μ则保持低水平。NPH的临床改善与机械网络的复杂性增加有关，然而，其固有强度仍然降低。
Normal pressure hydrocephalus (NPH) represents a chronic neurological disorder with increasing incidence. The symptoms of NPH may be relieved by surgically implanting a ventriculoperitoneal shunt to drain excess cerebrospinal fluid. However, the pathogenesis of NPH is not yet fully elucidated, and the clinical response of shunt treatment is hard to predict. According to current theories of NPH, altered mechanical properties of brain tissue seem to play an important role. Magnetic resonance elastography (MRE) is a unique method for measuring in vivo brain mechanics.In this study cerebral MRE was applied to test the viscoelastic properties of the brain in 20 patients with primary (N = 14) and secondary (N = 6) NPH prior and after (91 +/- 16 days) shunt placement. Viscoelastic parameters were derived from the complex modulus according to the rheological springpot model. This model provided two independent parameters mu and alpha, related to the inherent rigidity and topology of the mechanical network of brain tissue.The viscoelastic parameters mu and alpha were found to be decreased with -25% and -10%, respectively, compared to age-matched controls (P < 0.001). Interestingly, alpha increased after shunt placement (P < 0.001) to almost normal values whereas mu remained symptomatically low.The results indicate the fundamental role of altered viscoelastic properties of brain tissue during disease progression and tissue repair in NPH. Clinical improvement in NPH is associated with an increasing complexity of the mechanical network whose inherent strength, however, remains degraded.