中文摘要：

目的动态观察脑梗死后，远离梗死灶的锥体束纤维继发性损害的过程，并探讨其对神经功能恢复的影响。方法选择具单侧大脑中动脉（middle cerebral artery，MCA）供血区、累及内囊的单一病灶的脑梗死患者18例，选择年龄性别相匹配的健康志愿者18人作对照组。分别在发病的第1周、4周和第12周进行磁共振弥散张量成像（diffusion tensor imanging，DTI）检测，并行美国国立卫生研究院卒中评分（National Institutes of Health Stroke Scale，NIHSS）、简式Fugl-Meyer运动功能评分（FM）和Barthel生活指数（Barthel index，BI）评定。结果患者远离梗死灶的脑干（大脑脚、脑桥和延髓等部位的均数）部分弥散各向异性（fractional anisotropy，FA）值在第1周、4周和第12周各时间点逐渐减少（P〈0．01），而平均弥散量（mean diffusivity，MD）却无明显变化（P〉0．05）。脑干FA值减少的百分数与NIHSS减少的百分数（r=-0．46，P〈0．05）及FM增加的百分数（r=-0．61，P〈0．05）相关，与BI变化的百分数无明显相关（P〉0．05）。结论局灶性脑梗死后，锥体束纤维继发性损害会随时间延长而逐渐加重，并可能会阻碍患者神经功能的恢复。

英文摘要：

Objective To investigate the secondary degeneration after cerebral infarct as well as its potential significance for clinical practice. Methods Eighteen patients with a recently isolated MCA infarct underwent Diffusion Tensor Imaging （DTI） examinations and evaluations with the NIH Stroke Scale （ NIHSS）, the Fugl-Meyer motor scale （ FM ） and the barthel index （ BI ） at the first week （ W1 ）, the end of the fourth week （W4） and the twelfth week （W12） respectively. Eighteen age and gender matched health volunteers underwent DTI as controls. Mean diffusivity （MD） and fractional anisotropy （FA） measured on bilateral sides at internal capsule, cerebral peduncle, pons and medulla were analyzed. Results The FA values of pyramidal tract in brain stem （ derived from the mean value of cerebral peduncle, pons and medulla） in patients significantly decreased from W1 to W12 （P 〈0. 01 respectively）, but its MD showed no significant change （ P 〉 0. 05, respectively）. The percent reduction of brain stem FA value in patient group correlated to the percent reduction of NIHSS （ r =- 0. 46, P 〈 0. 05 ） and to the percent increase of FM （ r =- 0. 61, P 〈 0. 05 ）, but not to the percent change of BI （ P 〉 0. 05 ）. Conclusions After a focal cerebral infarct, the secondary degeneration in pyramidal tract distal to the primary lesion will persist at least 3 months, and may hamper the neurological recovery.