体感诱发电位对脑功能损伤的评估

目的运用体感诱发电位(SEP)评价脑功能损伤程度和预测预后,比较SEP与临床格拉斯哥昏迷评分(GCS)对脑功能损伤评估的准确性。方法对66例首次发病的急性脑血管疾病患者进行SEP动态监测,根据Judson分级标准进行SEP评价。分为重症组和非重症组各33例。结果SEP分级和GCS均与预后有显著相关性,SEP级别越高,GCS评分越低,预后越差。经logistic回归分析,SEP分级预测准确率高于GCS。结论分级量化的SEP较临床观察指标敏感、特异,能客观、准确地反映脑功能损伤程度和预后。     

Effects of blockade of cerebral lymphatic drainage on regional cerebral blood flow and brain edema after subarachnoid hemorrhage

The study was designed to observe the influence of blockade of cerebral lymphatic drainage on the regional cerebral blood flow (rCBF) and brain edema after experimental subarachnoid hemorrhage (SAH). Wistar rats were divided into non-SAH, SAH, and SAH plus cervical lymphatic blockade (SAH + CLB) groups. Autologous arterial hemolysate was injected into rat's cisterna magna to induce SAH. The rCBF was recorded continuously by a laser Doppler flowmeter. Intracranial pressure (ICP) was also monitored. After 24 hours and 72 hours of SAH, the rats were sacrificed and the brain was harvested for water content detection. It was found that there was no obvious change of rCBF and brain water content during the experiment in non-SAH group. An immediate and persistent drop in rCBF was found in SAH group. The drop in rCBF was more obvious in SAH + CLB group. CLB also worsened the SAH-induced increase in ICP. The brain water content 24 hours and 72 hours after induction of SAH in SAH group increased significantly. CLB led to a further increase of brain water content. In conclusion, blockade of cerebral lymphatic drainage pathway deteriorates the secondary cerebral ischemia and brain edema after SAH.     

The effect of high-dose phenylephrine versus epinephrine on regional cerebral blood flow during CPR

Prior studies have not found the alpha agonist phenylephrine, in a dose of 0.1 mg/kg, to be as effective as 0.20 mg/kg of epinephrine in improving regional cerebral blood flow (CBF) during CPR in swine. We undertook this study to assess whether higher doses of phenylephrine might improve regional CBF. Fifteen swine were allocated to receive either epinephrine 0.2 mg/kg, phenylephrine 1.0 mg/kg, or phenylephrine 10 mg/kg. Regional CBF measurements were made during normal sinus rhythm, during CPR, and during CPR following drug administration. Epinephrine 0.2 mg/kg was significantly better in improving regional CBF to the left and right cerebral cortices, cerebellum, midbrain, and cervical cord than was phenylephrine 1.0 mg/kg. There was no significant difference in regional CBF between the animals receiving epinephrine 0.2 mg/kg and phenylephrine 10 mg/kg. The study shows that large doses of epinephrine and phenylephrine may be required during CPR to improve regional cerebral blood flow following a prolonged arrest.     

Effects of phenytoin on regional cerebral blood flow, electroencephalogram, and electrolyte contents in cerebral blood and cerebral cortex following total cerebral ischemia in dogs

To study the protective effect of phenytoin on postischemic brain damage, total cerebral ischemia was produced for 8-12 min (aortic occlusion balloon catheter method) in 36 adult mongrel dogs. The regional cerebral blood flow (rCBF), sodium:potassium ratio in the cerebral cortex, electroencephalogram (EEG), and plasma electrolytes in the superior sagittal sinus blood were examined before ischemia and during the acute stage up to 120 min after recirculation in the control and phenytoin-treated groups. Measurement of rCBF (microsphere method) indicated easing of postischemic hypoperfusion of the cerebral cortex. The time from total cerebral ischemia to EEG electrical silence was significantly prolonged, and recovery of the electrical activity after recirculation was hastened. The increase in plasma potassium concentration in the superior sagittal sinus tended to be suppressed immediately after recirculation, and the sodium:potassium ratio in the cerebral cortex was lowered. Phenytoin increased the rCBF in the cerebral cortex, hastened the recovery of electrical activity, and stabilized the water and electrolyte balance in the cerebral cortex, suggesting some protecting effect on total cerebral ischemia.     

老年高血压患者局部脑血流改变对预后的影响

目的探讨无并发症的老年原发性高血压患者的局部脑血流（ｒＣＢＦ）改变及其对预后的影响。方法对经治疗将血压控制正常的３４例住院老年高血压患者（高血压组）和３０例血压正常的老年人（对照组）应用单光子发射计算机断层扫描行ｒＣＢＦ检查,并进行随访。结果高血压组有２９例（８５．３％）ｒＣＢＦ减少,而对照组有１３例（４３．３％,Ｐ＜０．００１）。高血压病程１０～３５年者,平均每例ｒＣＢＦ减少２．７处;病程２～９年者,平均减少１．５处（Ｐ＜０．０５）。高血压组３１例、对照组２９例平均随访（３６±２２）个月,原ｒＣＢＦ减少的高血压组患者中有１２例（４１．４％）发生脑梗死,１例脑出血死亡;对照组只有１例发生脑梗死（７．７％,Ｐ＜０．０５）。结论老年高血压患者尽管经治疗将血压控制正常,但ｒＣＢＦ减少仍十分常见,是发生缺血性脑卒中的主要原因。ｒＣＢＦ减少区域的数量与病程呈正相关。及早治疗高血压和改善脑血液循环,对预防缺血性脑卒中有重要意义     

The effect of PEEP ventilation on hemodynamics and regional blood flow with special regard to coronary blood flow

An experimental study was performed to evaluate the effects of positive end-expiratory pressure (PEEP) on central hemodynamics and on regional blood flow (RBF) using the radioactive microsphere (MS) method. Ten dogs with intact lungs and 10 dogs with oleic acid-induced pulmonary edema were ventilated with PEEP 10 and PEEP 20 (cmH2O). PEEP significantly reduced cardiac output (CO) by 25% at PEEP 10 and 40--50% at PEEP 20 despite volume expansion with dextran 60. RV afterload rose markedly due to a significant increase of pulmonary vascular resistance. PEEP tended to redistribute CO in favor of brain, heart and adrenals, at the expense of stomach, pancreas and thyroid glands. Hepatic artery flow was moderately reduced; renal RBF was seriously affected only when PEEP caused an extreme low-output state. RBF to the RV remained essentially unchanged, whereas RBF to the LV decreased, roughly paralleling the respective ventricular work. Nevertheless, the RV may suffer from underperfusion during PEEP, since its tension-time-index rises; this may indicate increased oxygen needs exceeding actual oxygen delivery.     

Decrease of regional cerebral blood flow in liver cirrhosis

OBJECTIVE: Alterations of regional cerebral blood flow (rCBF) in subjects with liver cirrhosis have not been fully evaluated. We evaluated quantitative changes in rCBF using single photon emission computed tomography (SPECT). METHODS: Twenty-eight Japanese patients with liver cirrhosis were enrolled in this study. None of them exhibited advanced hepatic encephalopathy at the time of examination. The cause of liver cirrhosis was viral infection in 26 patients; the cause was unknown in two patients. Child-Pugh classification of the patients was as follows: Group A, 12 patients; Group B, 12 patients; and Group C, four patients. The control group consisted of 25 age-matched healthy subjects. Radionuclide angiography was performed by rapid injection of Tc-99m ethyl cysteinate dimer (ECD) (740 MBq) via the right cubital vein, and then SPECT brain images were taken. Using the Patlak graphical method, rCBF values (ml/100 g per min) were calculated in the frontal, parietal, temporal and occipital lobes and cerebellum on SPECT images. RESULTS: The rCBF values were lower in cirrhotic patients than in controls, i.e. by 15% in the frontal lobe, by 12% in the parietal lobe, by 10% in the temporal and occipital lobes, and by 7% in the cerebellum. They decreased concomitantly with the severity of liver disease. A significant negative correlation was noted between rCBF values and Child-Pugh score in the frontal (P<0.01), parietal (P<0.05) and occipital lobes (P<0.01). rCBF values of each region were not correlated with age or with results of neuropsychological test. The degree of association between rCBF values and results of laboratory examination was generally poor. CONCLUSION: Patients with liver cirrhosis without advanced encephalopathy showed widespread reduction in rCBF; this reduction was particularly evident in the frontal lobe. Tc-99m ECD SPECT may be useful for evaluating cerebral functional changes in patients with liver cirrhosis.     

The cervical somatosensory evoked potential and its relation to F-wave activity

In 6 healthy volunteers aged 18-25 years cervical somatosensory evoked potentials (CEPs) were recorded following stimulation of the right median nerve at the wrist. At the same time the antidromically elicited individual F-waves evoked by any single impulse were recorded from the abductor pollicis brevis muscle. By means of selective averaging of the neck responses it could be shown that there was a close relationship between an F-wave-activity of 120-150 microV/stimulus or more during the trial and the appearance or the enhancement of a negative peak occurring 0.5-1.4 ms after the main CEP component N13. An F-wave-activity of more than 224 microV/stimulus regularly resulted in a total change of the CEP configuration.     

Changes in regional cerebral blood flow under hypothermic selective cerebral perfusion

OBJECTIVE: Currently the most frequently used perfusion technique during aortic arch surgery to prevent cerebral damage is hypothermic selective cerebral perfusion (SCP). Changes in cerebral blood flow (CBF) are known to occur during these procedures. We investigated regional changes of CBF under conditions of SCP in a porcine model. METHODS: In this blinded study, twenty-three juvenile pigs (20 - 22 kg) were randomized after cooling to 20 degrees C on CPB. Group I (n = 12) underwent SCP for 90 minutes, while group II (n = 11) underwent total body perfusion. Fluorescent microspheres were injected at seven time-points to calculate total and regional CBF. Hemodynamics, intracranial pressure (ICP), cerebrovascular resistance (CVR) and oxygen consumption were assessed. Tissue samples from the neocortex, cerebellum, hippocampus and brain stem were taken for a microsphere count. RESULTS: CBF decreased significantly (p = 0.0001) during cooling, but remained at significantly higher levels with SCP than with CPB throughout perfusion (p < 0.0001) and recovery (p < 0.0001). These findings were similar among all regions of the brain, certainly at different levels. Neocortex CBF decreased 50%, whereas brain stem and hippocampus CBF decreased by only 25 % during total body perfusion. All four regions showed 10 - 20% less CBF in the post-CPB period. CBF during SCP did not fall by more than 20% in any analysed region. The hippocampus turned out to have the lowest CBF, while the neocortex showed the highest CBF. CONCLUSION: SCP improves CBF in all regions of the brain. Our study characterizes the brain specific hierarchy of blood flow during SCP and total body perfusion. These dynamics are highly relevant for clinical strategies of perfusion.     

Aging, regional cerebral blood flow, and neuropsychological functioning

Previous studies found changes in regional cerebral blood flow (rCBF) patterns related to both age and various cognitive tasks. However, no study has yet demonstrated a relationship between rCBF and performance on the Luria-Nebraska Neuropsychological Battery (LNNB) in an elderly group. Seventy-nine elderly volunteers (56-88 years old), both healthy and demented, underwent the 133xenon inhalation rCBF procedure and were given the LNNB. The decrements in the gray-matter blood flow paralleled decrements in performance on the LNNB. Using partial correlations, a significant proportion of shared variance was observed between gray-matter blood flow and the LNNB scales. However, there was much less of a relationship between white-matter blood flow and performance on the LNNB. This study suggests that even within a restricted age sample rCBF is related in a global way to neuropsychological functioning.     

The effect of enalapril maleate on cerebral blood flow in chronic cerebral infarction.

The influence of long-term oral administration of enalapril maleate (an angiotensin II-converting enzyme inhibitor) on regional cerebral blood flow (rCBF) was studied in 10 patients with chronic cerebral infarction. The rCBF was measured by a 133Xe inhalation method before and after a mean of sixty-five days' administration of 5 mg of enalapril. Results: Mean arterial blood pressure (MABP) was mildly decreased in 6 patients, but the average change in MABP was not significant (Endtidal partial pressure of carbon dioxide (PeC02) was not changed significantly. The mean rCBF was increased by 8% after administration of enalapril (0.05 less than p less than 0.1) There was no significant correlation between percent change in MABP and the percent change in rCBF. These results indicate that enalapril has not only antihypertensive action but also a beneficial effect on the cerebral circulation in patients with chronic cerebral infarction.     

The cervical somatosensory evoked potential in lesions of the cortical efferents

Cervical and cortical somatosensory evoked potentials to median nerve stimulation were analysed in 20 patients with unilateral central paresis of the arm. Neither the configuration nor the latency and amplitude measures of the neck potential did reveal any association with pathological alterations of cortical efferents or with abnormal cortically evoked responses. Thus, also in this population the evaluation of cervical potentials can be done according to the known criteria.     

Effect of long-term administration of buflomedil on regional cerebral blood flow in chronic cerebral infarction

The influence of long-term oral administration of buflomedil on regional cerebral blood flow was investigated in 10 patients with chronic cerebral infarction and mild to moderate mental deterioration. Patients were given 150 mg buflomedil three times daily for a period of eight weeks. Regional cerebral blood flow (rCBF) was measured in patients before they began buflomedil treatment and during the last week of treatment. The interval of the rCBF measurements in the control subjects (n = 12) ranged from seven to forty-eight days. Mental function in the patients studied was evaluated by use of Hasegawa's simple intelligence scale for the aged and Zung's self-rating depression scale, before and during the last week of buflomedil treatment. The results showed a mean increase in rCBF of 10.5% +/- 12.1% in the patient group. The control group demonstrated virtually no change in rCBF measurements. Improvements in the mental function scores of the buflomedil-treated group were noted, and 5 of the 10 patients reported improvement in subjective symptoms.     

Mapping regional cerebral vascular transit time by simultaneous determination of local cerebral blood flow and local cerebral blood volume

We developed a method for autoradiographic mapping of regional cerebral transit time (CTT) by simultaneously measuring local cerebral blood flow (LCBF) and local cerebral blood volume (LCBV). Previously described single-tracer techniques for determination of LCBF and LCBV were modified for dual-tracer,^99mTc and¹⁴C, autoradiography and used to create digital images of LCBF and LCBV from the same brain sections in a series of normal rats. The images were aligned and ratio images (LCBV/LCBF) were then generated which reflected CTT. Regional cerebral transit time was found to vary significantly throughout the brain in a pattern only partially related to that of blood flow. Such CTT heterogeneity could cause errors in implementation of kinetic models which assume uniform or monovariant distributions of vascular transit time.     

Effects of thyrotropin-releasing hormone on regional cerebral blood flow in man.

To assess the regional changes in cerebral blood flow, 10 healthy volunteers were given 400 micrograms thyrotropin-releasing hormone iv in a double-blind, randomized, cross-over study. Regional cerebral blood flow was determined simultaneously in two slices of the brain, using a single photon emission computerized tomograph and inhalation of 133Xe. Thyrotropin-releasing hormone caused a significant mean increase of 3.7% (range -8.8-22.7) in blood flow in a region consistent with the left thalamus compared to placebo (3.2% decrease). In 25 other regions no significant change was detected. The thalamic region has previously been shown to be a region especially affected by thyrotropin-releasing hormone in animal studies. The thyrotropin-releasing hormone injection was followed by a minor rise in systemic blood pressure, but not a rise that could affect the cerebral blood flow. The effect of thyrotropin-releasing hormone on the regional cerebral blood flow in the thalamic region was much lower compared to changes found in sedated animals given a hundredfold higher dose of thyrotropin-releasing hormone.     

巨大脑动静脉畸形手术前后脑局部皮层血流变化的研究

目的研究巨大脑动静脉畸形（AVM）手术切除后的脑皮质血流变化,指导临床降压治疗及血压监测等。方法AVM直径〉6cm的患者26例,用激光多普勒血流仪（LDF）分别记录切除AVM前、术后即刻、术后1d、术后2d、术后3d的脑血流值,比较血流变化情况,观察术后脑血流稳定和再灌注水平下降所需时间。结果巨大脑AVM切除后脑局部的皮层血流较术前立即增高（P〈0．05）,术后2d与术后1d、术后即刻比较均无明显改变（P〉0．05）;术后3d较术后2d有所降低（P〈0．05）。讨论巨大AVM切除后局部脑组织的血流明显增加,术后2d达最高,术后3d开始有明显的下降,但尚未达到术前的水平。     

The effect of temperature, mean arterial pressure, and cardiopulmonary bypass flows on somatosensory evoked potential latency in man

Median nerve somatosensory evoked potentials were recorded in 21 patients undergoing cardiac surgical procedures utilizing cardiopulmonary bypass, in order to establish the effects of hypothermia, reductions in mean arterial pressure, and alterations in cardiopulmonary bypass flows on evoked potential latency. Induction and maintenance of anesthesia with fentanyl caused a significant prolongation of latency of the first cortical peak. Temperature changes were linearly correlated with changes in latency for peaks recorded from Erb's point (r = -0.843, p less than 0.01) and the contralateral cortex (r = 0.843, p less than 0.01). There was no significant effect of mean arterial pressure or cardiopulmonary bypass flow reductions on latencies under the conditions of this study. Our results emphasize the importance of monitoring peripheral and first cortical peak latencies in evaluating somatosensory evoked potentials. It is suggested that peak latency prolongations beyond those predicted by temperature alterations may be indicative of hypoperfusion.     

尼莫地平对脑血管痉挛鼠体感诱发电位和脑组织内皮素—1含量的影响

目的：探讨蛛网膜下腔出血（SAH）后脑血管痉挛（CVS）对体感诱发电位（SEP）和脑组织内皮素－1（ET－1）的影响,及尼莫地平（ND）的保护作用。方法：对单纯SAH组和ND处理组大鼠观察手术前后基底动脉管径,并检验24h内局部脑血流量（rCBF)、SEP极脑组织ET－1含量的动脉变化。结果：SAH组大鼠在诱导SAH后rCBF立即降低,并持续24h,同时有基底动脉痉挛;SAH后1h开始至24hSEP潜伏期逐渐延长,脑组织ET－1含量显著增加。ND使上述变化均明显减轻。结论：SAH后CVS可通过脑血流的降低、脑组织ET－1增加而导致SEP潜伏期延长,ND对之具有保护作用。