Sakatani K, Xie Y, Lichty W, Li S, Zuo H
Department of Neurosurgery, China-Japan Friendship Hospital, Tsinghua University China-Japan Friendship Institute of Medical Sciences, Beijing, China.
Stroke. 1998 Jul;29(7):1299-304. doi: 10.1161/01.str.29.7.1299.
In normal subjects, regional cerebral blood flow (rCBF) is greatly increased by neuronal activity, whereas the cerebral metabolic rate for O2 is increased only slightly. However, it is not clear what kinds of cerebral blood oxygenation and hemodynamic changes can be induced by language activities in language-relevant areas of poststroke aphasics. In the present study, we investigated the difference in the changes of cerebral blood oxygenation and hemodynamics in the left prefrontal cortex induced by language activities between normal subjects, poststroke nonaphasic patients, and nonfluent aphasic patients using near-infrared spectroscopy (NIRS).
Twenty-nine participants performed speech tasks, such as confrontational naming, to evaluate changes among poststroke nonfluent (Broca's) aphasia patients (10 cases; mean+/-SEM, 56.9+/-2.2 years), age-matched normal subjects (13 cases; 50.7+/-2.2 years) and poststroke nonaphasic patients (6 cases; 52.5+/-3.9 years). The optodes of NIRS were placed over the left prefrontal cortex. We analyzed the NIRS parameter (oxyhemoglobin [oxy-Hb], deoxyhemoglobin [deoxy-Hb], and total hemoglobin [total-Hb]) changes by qualitative pattern analysis of the parameter changes and quantitative analysis of the parameter values among the groups.
The most common NIRS parameter change was an increase in oxy-Hb and total-Hb, with a slight decrease or no change in deoxy-Hb in the normal subjects (5 of 13 cases, 38.5%) and the nonaphasic cerebrovascular disease (CVD) patients (3 of 6 cases, 50.0%). In contrast, the most common pattern in the aphasic patients was an increase of deoxy-Hb, with an increase of oxy-Hb and total-Hb (5 of 10 cases, 50%). However, this pattern was observed in only 3 of 13 cases (23.1%) in the normal subjects and 1 of 6 cases (16.7%) in the nonaphasic CVD patients. The mean (+/-SEM) changes of deoxy-Hb of the aphasic patients, the normal subjects, and the nonaphasic CVD patients were 0.78+/-0.29, 0.06+/-0.16, and -0.18 +/- 0.22, respectively. The statistical analysis demonstrated a significant effect for deoxy-Hb (P<0.05), with the aphasic patients differing significantly from the normal subjects and the nonaphasic CVD patients, while the 2 nonaphasic groups did not differ from each other.
The present results demonstrate a multiplicity of language-activated cerebral blood oxygenation and hemodynamic changes in the left prefrontal cortex in the nonaphasic and aphasic groups. The increase of deoxy-Hb with increases of oxy-Hb and total-Hb in the aphasics during language tasks suggests that the left prefrontal cortex of the aphasics utilizes more oxygen than the nonaphasics during language tasks. Finally, functional MRI, which images the activation area in the brain by detecting the reduced concentration of deoxy-Hb during neuronal activation, should be performed on the patients with cerebral dysfunction, giving special consideration to the possible multiplicity of the rCBF and cerebral oxygen metabolism responses to functional tasks.
在正常受试者中，神经元活动可使局部脑血流量（rCBF）大幅增加，而脑氧代谢率仅略有增加。然而，尚不清楚中风后失语症患者语言相关区域的语言活动能引起何种脑血氧和血流动力学变化。在本研究中，我们使用近红外光谱（NIRS）研究了正常受试者、中风后非失语患者和非流利性失语患者语言活动引起的左前额叶皮质脑血氧和血流动力学变化的差异。
29名参与者进行了诸如对物品命名等言语任务，以评估中风后非流利性（布罗卡氏）失语症患者（10例；平均±标准误，56.9±2.2岁）、年龄匹配的正常受试者（13例；50.7±2.2岁）和中风后非失语患者（6例；52.5±3.9岁）之间的变化。NIRS的光极置于左前额叶皮质上方。我们通过参数变化的定性模式分析和组间参数值的定量分析，分析了NIRS参数（氧合血红蛋白[oxy-Hb]、脱氧血红蛋白[deoxy-Hb]和总血红蛋白[total-Hb]）的变化。
最常见的NIRS参数变化是正常受试者（13例中的5例，38.5%）和非失语性脑血管疾病（CVD）患者（6例中的3例，50.0%）的氧合血红蛋白和总血红蛋白增加，脱氧血红蛋白略有下降或无变化。相比之下,失语症患者最常见的模式是脱氧血红蛋白增加，同时氧合血红蛋白和总血红蛋白增加（10例中的5例，50%）。然而，这种模式在正常受试者的13例中仅3例（23.1%）以及非失语性CVD患者的6例中仅1例（16.7%）中观察到。失语症患者、正常受试者和非失语性CVD患者的脱氧血红蛋白平均（±标准误）变化分别为0.78±0.29、0.06±0.16和-0.18±0.22。统计分析显示脱氧血红蛋白有显著影响（P<0.05），失语症患者与正常受试者和非失语性CVD患者有显著差异，而两个非失语组之间无差异。
目前的结果表明，在非失语组和失语组中，左前额叶皮质存在多种语言激活的脑血氧和血流动力学变化。失语症患者在语言任务期间脱氧血红蛋白随氧合血红蛋白和总血红蛋白增加，这表明失语症患者的左前额叶皮质在语言任务期间比非失语症患者消耗更多的氧气。最后，对于脑功能障碍患者，应进行功能磁共振成像（通过检测神经元激活期间脱氧血红蛋白浓度降低来成像脑内激活区域），尤其要考虑到rCBF和脑氧代谢对功能任务反应可能的多样性。
