Hans Berger Clinic for Neurology, Jena University Hospital, Friedrich-Schiller-University Jena, Erlanger Allee 101, Jena, Germany.
Cerebrovasc Dis. 2010;30(4):380-8. doi: 10.1159/000319573. Epub 2010 Aug 5.
The intention of this study was the prospective analysis of Wallerian degeneration of the pyramidal tract after paramedian pons infarction.
Patients with paramedian pons infarct underwent MR imaging including diffusion tensor imaging at admission and got 1-3 MR scans up to 6 months of follow-up. Clinical scores and transcranial magnetic stimulation were acquired in the acute phase and 3-6 months later. The pyramidal tracts were manually segmented in fractional anisotropy (FA) color maps after coregistration of all MR datasets of each patient. FA as well as axial and radial diffusivity were measured in the volume of lesioned and contralateral pyramidal tracts distally to the ischemic lesion.
From 11 patients studied, 7 developed Wallerian degeneration detected as statistically significant decrease in FA over time in the distal pyramidal tract. Wallerian degeneration could be detected at the earliest between the first and the third days after the onset of symptoms. A continuous decrease in FA and an increase in axial and radial diffusivity in degenerating pyramidal tracts over time were demonstrated. A significant correlation between NIHSS score on admission and the slope of relative axial diffusivity and a significant correlation between motor-evoked potential amplitudes of the arm on admission and the outcome relative FA was found.
The initial MR image cannot predict the following Wallerian degeneration. However, the severity of motor disturbance and the motor-evoked potential of the arm on admission could be possible parameters to predict Wallerian degeneration. For estimation of Wallerian degeneration over time, at least 2 diffusion tensor imaging measurements have to be done at different time points.
本研究旨在前瞻性分析脑桥旁正中梗死后锥体束的瓦勒氏变性。
脑桥旁正中梗死患者入院时行磁共振成像(MRI)检查,包括弥散张量成像,在随访的 6 个月内行 1 到 3 次 MRI 扫描。在急性期和 3 到 6 个月后采集临床评分和经颅磁刺激数据。通过对每位患者的所有 MRI 数据集进行配准,在各向异性分数(FA)彩色图谱上手动分割锥体束。在病变对侧锥体束和缺血病变远端的损伤锥体束中测量 FA 以及轴向和径向弥散度。
从 11 名研究的患者中,有 7 名患者出现了瓦勒氏变性,表现为远端锥体束的 FA 随时间的推移呈统计学显著下降。在症状出现后的最早 1 到 3 天内就可以检测到瓦勒氏变性。随时间推移,变性锥体束的 FA 连续下降,轴向和径向弥散度增加。入院时 NIHSS 评分与相对轴向弥散度斜率之间,以及入院时上肢运动诱发电位振幅与相对 FA 结果之间存在显著相关性。
初始 MRI 图像不能预测随后的瓦勒氏变性。然而,入院时运动障碍的严重程度和上肢运动诱发电位可能是预测瓦勒氏变性的参数。为了估计随时间推移的瓦勒氏变性,至少需要在不同时间点进行 2 次弥散张量成像测量。