Effects of dextromethorphan on regional cerebral blood flow in focal cerebral ischemia

Dextromethorphan (DM), a noncompetitive NMDA antagonist, has been demonstrated to reduce ischemic neuronal damage and edema, but DM's influence on cerebral blood flow has not been extensively studied. In this investigation, it is shown that DM has significant effects on regional cerebral blood flow (rCBF) patterns in a rabbit model of focal cerebral ischemia. rCBF was measured using radioactive microspheres following a 1 h permanent occlusion of the left internal carotid, anterior cerebral, and middle cerebral arteries in rabbits. Somatosensory evoked potentials (SEPs) were used to assess the degree of ischemia; only animals where SEPs were completely abolished were used for a frequency distribution analysis of rCBF. It was found that there were significantly more regions with lower flows in animals treated with normal saline (NS) (n = 7) compared to animals treated with DM (n = 7) (p less than 0.05, ipsilateral left side; p less than 0.001, contralateral right side). The frequency distribution medians were 27.5 ml 100 g-1 min-1 (left) and 70.0 ml 100 g-1 min-1 (right) in the NS group vs. 34.5 ml 100 g-1 min-1 (left) and 80.5 ml 100 g-1 min-1 (right) in the DM group. The left and right hemispheric regional means were 29.4 +/- 20 and 74.3 +/- 23 ml 100 g-1 min-1, respectively, in the NS group vs. 34.4 +/- 16 and 91.0 +/- 28 ml 100 g-1 min-1, respectively, in the DM group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regional cerebral blood flow in children--normal value and regional distribution of cerebral blood flow in childhood

The changes in CBF and rCBF through the entire age range include the rapid period in childhood was reported. Sixteen children between the ages of 1 and 15 and 14 adults were studied. These 30 subjects were either volunteers of out-patients without CT and EEG abnormalities. rCBF was measured by the 133Xe intravenous injection method using Varmet rCBF analyzer. Ther relationship between age and CBF, the correlation coefficient was calculated based on the regression equations and the regression curve with the highest correlation was chosen. For the analysis of rCBF, he mean rCBF values (ISI) of 3 channels corresponding to the frontal, temporal, parietal and occipital lobes were expressed as a percentage of the hemispheric CBF. The hemispheric blood flow (ISI and CBF gray) of children less than 5 years of age was approximately twice that found in adults. This value decreased rapidly with age and in the 10-15 years the blood flow was approximately 1.3-fold that of adults. Thereafter, there was a slow decrease and a negative correlation with age was found. The decrease showed the correlation on the following equations; y = 146.5 - 58.5 log x. (r = -0.903) for ISI and log y = 2.26 - 0.29 log x. (r = -0.881) for CBF gray, which was statistically significant. In contrast, the CBF white showed a slightly higher value in the 1-2 years old children, but thereafter the CBF did not show a notable decreases with age. Through the entire age range, a best fit for the Fw values was found with : y = 18.3 + 37.5/x. (r = 0.798), which was also statistically significant.     

Sequential assessment of regional cerebral blood flow, regional cerebral blood volume, and blood-brain barrier in focal cerebral ischemia: a case report

Regional CBF (rCBF) and regional cerebral blood volume (rCBV) were evaluated by N,N,N'-trimethyl-N'-(2)-hydroxy-3-methyl-5-[123I]iodobenzyl-1, 3-propanediamine-2 HCl- and 99mTC-labeled red blood cells, respectively, and single-photon emission computerized tomography (SPECT) in a patient with focal cerebral ischemia. Sequential transmission computerized tomography (TCT) and SPECT functional data were compared with clinical findings to monitor the pathophysiological events occurring in stroke. A lack of correlation between rCBF-rCBV distributions and blood-brain barrier (BBB) breakdown was found in the acute phase. In the face of more prolonged alteration of BBB, as seen by TCT enhancement, a rapid evolution of transient phenomena such as luxury perfusion was shown by SPECT studies. Follow-up of the patient demonstrated a correlation between the neurological recovery and a parallel relative improvement of the cerebral perfusion.     

血液光量子疗法对局灶性脑缺血大鼠大脑皮层局部血流量和脑水肿的影响

本文动态观测了光量子疗法治疗血栓栓塞性脑缺血大鼠,大脑皮层局部血流量(rCBF)及脑水肿的变化。结果:缺血6小时经光量子血液治疗2小时后,rCBF于注后30min明显增加,达19.78％(P<0.01),以后各点维持在一定水平,2小时增加到19.30(P<0.05)。脑组织比重:缺血中心区未见明显改善(P>0.1)而半暗区组织比重非常明显增加(P<0.001),可见水肿明显减轻。说明光量子疗法增加rCBF,减轻半暗区水肿。     

Drug effects on regional cerebral blood flow in focal cerebrovascular disease

Hemispheric and regional cerebral blood flow (rCBF) were measured using the scintillation camera connected to a 1600-word memory and digital magnetic tape in a total of 211 patients, of whom 175 suffered from cerebrovascular disease and 36 from other neurological deficits. The effects of different drugs (2 sympathomimetics with α-and 2 with β-receptor stimulation, a central nervous system stimulant, a xanthine, 2 papaverine-like drugs, a vasodilator of cerebral vessels, 1 haemodiluting and 1 dehydrating agent) on hemispheric and regional blood flow were investigated and the results were compared to the blood flow changes between 2 measurements in untreated control patients. For the evaluation of effects on rCBF a regression analysis was applied. Homogeneous and heterogeneous responses of the regional cerebral circulation were observed: β-receptor stimulants and an α- and β-receptor stimulant in combination with xanthine caused a statistically-significant diffuse depression of rCBF, while the cerebral vasodilator hexobendine and haemodiluting and dehydrating agents caused a diffuse increase of rCBF in many cases. A significant heterogeneous response in the form of an intracerebral steal syndrome was observed only with the cerebral vasodilator, while the heterogeneous response in the form of an inverse cerebral steal syndrome was seen after the application of xanthines, papaverine-like drugs and haemodiluting and dehydrating agents. The data obtained in experimental studies of drug effects on cerebral blood flow provide the basis for controlled clinical studies, by which the therapeutic value of drugs for the treatment of cerebrovascular disease has to be proven.     

Relationship between regional cerebral metabolism and consciousness disturbance in traumatic diffuse brain injury without large focal lesions: an FDG-PET study with statistical parametric mapping analysis

Background

The cerebral metabolism of patients in the chronic stage of traumatic diffuse brain injury (TDBI) has not been fully investigated.

Aim

To study the relationship between regional cerebral metabolism (rCM) and consciousness disturbance in patients with TDBI.

Methods

52 patients with TDBI in the chronic stage without large focal lesions were enrolled, and rCM was evaluated by fluorine‐18‐fluorodeoxyglucose positron emission tomography (FDG‐PET) with statistical parametric mapping (SPM). All the patients were found to have disturbed consciousness or cognitive function and were divided into the following three groups: group A (n = 22), patients in a state with higher brain dysfunction; group B (n = 13), patients in a minimally conscious state; and group C (n = 17), patients in a vegetative state. rCM patterns on FDG‐PET among these groups were evaluated and compared with those of normal control subjects on statistical parametric maps.

Results

Hypometabolism was consistently indicated bilaterally in the medial prefrontal regions, the medial frontobasal regions, the cingulate gyrus and the thalamus. Hypometabolism in these regions was the most widespread and prominent in group C, and that in group B was more widespread and prominent than that in group A.

Conclusions

Bilateral hypometabolism in the medial prefrontal regions, the medial frontobasal regions, the cingulate gyrus and the thalamus may reflect the clinical deterioration of TDBI, which is due to functional and structural disconnections of neural networks rather than due to direct cerebral focal contusion.Diffuse axonal injury (DAI) results in a wide range of neuropsychological and neurological deficits. Patients with DAI show complex combinations of disorders of memory, attention and executive functions, slowed information processing, modifications of behaviour and personality, and disturbed communication and consciousness.¹ These disorders may impose a great burden on the family of the patient with a head injury and compromise psychosocial and vocational reintegration.² Indeed, cognitive, behavioural and personality changes are major causes of the failure of patients with DAI to return to work.In patients with DAI, MRI shows lesions in the corpus callosum, brain stem, internal capsule and the grey matter–white matter junction or the deep matter.^3,4,5 Global MRI indices of patients with DAI, such as ventricular enlargement or atrophy of the white matter tracts (corpus callosum, fornix, internal capsule), correlate well with cognitive outcomes.^6,7 In contrast, neurobehavioural disorders after DAI are reportedly poorly correlated with focal lesions that are detected by morphological neuroimaging techniques, such as CT or MRI.^7,8Cerebral metabolic imaging with positron emission tomography (PET) is useful in assessing the regional cerebral metabolism (rCM). PET studies on cerebral metabolism in patients with traumatic brain injury have been conducted at the acute⁹ or subacute–chronic stages,^2,10,11 and those with region‐of‐interest (ROI) techniques have disclosed a close link between cognitive and behavioural disorders and decreased cortical metabolism in the prefrontal and cingulate cortices in patients with severe DAI.²Patients with DAI have neurological, cognitive and behavioural dysfunctions, which become stable in the chronic stage. The relationship between these dysfunctions and rCM deviations has never been studied in detail. Limitations do exist in the assessment of rCM with ROI techniques. ROI techniques depend either on subjective assessment to establish differences from normal tracer distribution on functional activity maps or on the relatively arbitrary size, shape and placement of the ROIs. As a result, some areas of the brain may not be explored. Statistical parametric mapping (SPM) analysis is an alternative voxel‐by‐voxel analysis method that can avoid subjectivities. To investigate the relationship between cognitive and behavioural disorders, consciousness disturbance and rCM, we conducted a fluorine‐18‐fluorodeoxyglucose‐PET (FDG‐PET) study with SPM analysis in patients with traumatic diffuse brain injury (TDBI) at the chronic stage, which histopathologically is assumed to be mostly DAI.     

尤瑞克林对大鼠局灶性脑缺血半暗带脑血流量影响的研究

目的 研究尤瑞克林对大鼠局灶性脑缺血后半暗带血流量的影响.方法 线栓法制备大鼠局灶性脑缺血模型,应用激光多普勒血流监测仪经颅测量脑缺血中心区及半暗带脑血流量,1%2,3,5-三苯基氯化四氮唑染色法测定脑梗死体积.结果 脑缺血半暗带局部脑血流(regional cerebral blood flow,rCBF)在大、中剂量尤瑞克林给药后5 min开始上升,在20 min达峰值,小剂量尤瑞克林对缺血半暗带rCBF变化则无明显影响.脑缺血24 h后生理盐水组、大中小剂量尤瑞克林治疗组梗塞面积分别为30.38%±2.76%,16.44%±3.17%,16.61%±2.76%,28.58%±2.38%,大中剂量尤瑞克林组与生理盐水组比较有统计学差异(P<0.05),小剂量尤瑞克林组与生理盐水组比较无统计学差异(P>0.05).结论 尤瑞克林可以减少大鼠局灶性脑缺血后梗塞面积,其治疗作用可能与增加缺血半暗带局部脑血流量有关.     

Effect of Fluosol on oxygen availability, regional cerebral blood flow, and infarct size in a model of temporary focal cerebral ischemia

Twenty-four cats had an intravenous infusion of either Fluosol or saline and then were subjected to 2 hours of middle cerebral artery occlusion. All the animals infused with Fluosol and one-half the animals infused with saline were ventilated with 100% O2. Tissue oxygen availability and regional cerebral blood flow were measured by platinum electrodes using direct voltage recordings for oxygen measurements and hydrogen clearance curves for measurements of cerebral blood flow. With 100% oxygenation tissue oxygen availability increased significantly in the Fluosol treated animals, however, during the time of ischemia oxygen availability decreased below baseline values to about an equal level whether the animals were treated with Fluosol or saline. Regional cerebral blood flow fell to a similar value in all groups during the time of occlusion. One hour after reperfusion blood flow increased considerably above baseline values in all groups and oxygen availability also increased in all groups but particularly in the Fluosol treated animals. Overall mortality and the size of infarction 1 week after the ischemic insult were not significantly different in the three groups. Mortality was directly related to the size of the infarct which, in turn, was related to the degree of ischemia during the time of occlusion.     

Continuous regional cerebral blood flow monitoring in the neurosurgical intensive care unit.

The aim of this study was to examine the intracranial pressure (ICP) and regional cerebral blood flow (rCoBF) changes during the acute stage of severe head injury and to improve outcome by modifying treatment modalities using real-time ICP and rCoBF data. Twenty patients with moderate or severe head injury that were monitored in our neurosurgical intensive care unit were included in this study. The changes in ICP, rCoBF and the relationship of ICP/rCoBF were observed. In patients with high ICP and low rCoBF, mannitol improves the rCoBF and decreases the ICP of these patients. When low rCoBF exists, hyperventilation may lead to a rapid further decline of rCoBF, however, some hyperemic brains respond well to hyperventilation treatment. Triple-H therapy is suitable for those with low rCoBF without significantly high ICP, which is an abnormal condition considered to be caused by vasospasm.     

Gender differences in regional cerebral blood flow

Gender differences have been noted in neurobehavioral studies. The 133xenon inhalation method for measuring regional cerebral blood flow (rCBF) can contribute to the understanding of the neural basis of gender differences in brain function. Few studies have examined gender differences in rCBF. In studies of normal subjects, women have higher rates of CBF than men, and this is related to age. Usually by the sixth decade men and women have similar flow rates. Fewer studies on rCBF in schizophrenia have examined sex differences. The pattern of higher flows for females maintains, but its correlates with gender differences in clinical as well as other parameters of brain function remain to be examined.     

Sex differences in regional cerebral blood flow

Regional cerebral blood flow was measured by the 133-xenon inhalation method during resting in 38 healthy men and 38 healthy women matched pairwise for age in the range 18-72 years. The results showed 11% higher global flow level in the women in all ages. A similar and significant regression of flow by age was seen for both sexes. The regional flow distribution also showed some sex-related differences. Frontal regions showed an asymmetry in the men with higher values on the right side. The female flows were more symmetric. As a hypothesis, it is suggested that the higher flow level in women may be a systemic phenomenon. In fact, other authors have found a higher cardiac index in females. The sex differences in regional flow pattern might be due to differences in the functional organization of the cortex and/or to differences in the mental processes of the "resting" state.     

Sex roles and regional cerebral blood flow

Several investigators have reported higher resting cerebral blood flow (CBF) in females as compared to males. The relationship between sex roles as quantified by Bem's Sex Role Inventory and CBF was evaluated in 106 right-handed, physically and mentally healthy, drug-free volunteers. CBF was measured noninvasively with the 133xenon inhalation technique. The CBF values correlated inversely with age and positively with carbon dioxide levels, confirming previous reports. Females obtained significantly higher CBF values than males; the differences tended to be most obvious in frontal regions. Males and females who scored high on femininity showed higher CBF as compared to low-femininity subjects even after the effect of sex was covaried out. High masculine sex role tended to be associated with lower CBF, but the effect was less clear.     

Diagnostic value of regional cerebral blood flow in SPECT pattern in Alzheimer's disease]

Regional cerebral blood flow in SPECT pattern was estimated in 20 cases of Alzheimer disease. In all patients diffuse hypoperfusion was found evidencing a great diagnostic value of SPECT. A special significance has the study of regional cerebral blood flow in the differential diagnosis of Alzheimer disease, frontal lobe dementia and pseudodementia in major depression.     

Correlation between diffuse alpha wave pattern of EEG and hyperfrontal pattern of regional cerebral blood flow

Regional cerebral blood flow (rCBF) was measured in three groups; (1) 20 healthy subjects, (2) 14 patients with diffuse alpha wave pattern of EEG, (3) 14 patients without diffuse alpha wave pattern matching with ages of group 2. In the group 2, one patient with transient ischemic attack, 7 with reversible ischemic neurological deficit, 3 with vertebro-basilar insufficiency, 2 with minor stroke and one with posttraumatic sequelae were selected for rCBF measurements. In the group 3, 3 patients with transient ischemic attack, 7 with reversible ischemic neurological deficit, 2 with vertebro-basilar insufficiency and 2 with minor stroke were selected for rCBF measurements. Electroencephalographic analyses were performed by using a BERG-Fourier Analyzer, simultaneously with rCBF measurements. All patients in the group 2 had diffuse alpha wave (generalized continuous simple rhythmic alpha wave--Hori et al) pattern of EEG. Regional cerebral blood flow measurement was performed with intracarotid injection method of 133Xe (10 mCi) by using the scintillation camera and on-line computer system. 133Xe clearance curve from the whole hemisphere were computed by height over area method. Regional value were obtained from brain areas of 6 mm X 6 mm. Mean hemispheric values were 59.2 +/- 7.9 ml/100 g/min in the group 1, 47.8 +/- 4.9 ml/100 g/min in the group 2 and 49.0 +/- 3.7 ml/100 g/min in the group 3. Although difference between group 2 and 3 was not significant, difference between group 1 and 2 was significant (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognostic value of cerebral blood flow autoregulation in the long-term prognosis of ischemic cerebrovascular disease

The correlation between long-term prognosis, cerebral blood flow (CBF) and CBF autoregulation was studied in 34 patients with cerebral infarction (mean age, 64 years). CBF was measured by the nitrous oxide method 1–6 months (mean 87 days) after disease onset. CBF autoregulation was evaluated quantitatively from the Dysautoregulation Index (DI) (ΔCBF/Δeffective MABP). Reductions in effective MABP were induced with a tilt table. No significant correlation was noted among CBF, DI and activities of daily living at the time of measurement. The patients' physical condition was reevaluated by questionnaire 2 years or more (mean 32 months) later. Better functional state at follow-up was related to higher CBF and lower DI values although the differences were not significant. The relationships among CBF, DI and changes in physical condition during the period were evaluated. The mean CBF values in patients with a better prognosis exceeded those of poor prognosis patients. The CBF values in the group who became independent significantly exceeded those in the group that deteriorated (P < 0.05). The CBF values in the latter showed small but significant decreases during head-up tilting (P < 0.05). The DI in this group was significantly higher than in the groups with a less severe outcome (P < 0.01, P < 0.05, respectively).In conclusion, determinations of CBF autoregulation, together with flow values, in the chronic state may have some value in predicting the long-term prognosis in cerebral infarction.     

急性双侧大脑半球弥漫性脑肿胀患者颅内压监测及意义

目的 探讨有创颅内压(ICP)监测对治疗创伤性急性双侧半球弥漫性脑肿胀的指导作用以及判断预后的意义.方法 2010年2月至2011年10月湖州市解放军第98医院神经外科在有创ICP监测下治疗创伤性急性双侧半球弥漫性脑肿胀59例,前瞻性研究患者入院时ICP、去骨瓣减压患者术前ICP和术后ICP等临床资料,按伤后6个月的GOS评分分为恢复良好组(GOS4 ～5分)和恢复不良组(GOS 1 ～3分).探讨入院时ICP、去骨瓣减压患者术前ICP、术后ICP与预后的关系.结果 本组病例恢复良好率69％ (41/59),恢复不良率31％ (18/59),病死率15％ (9/59).入院时GCS≥9分的患者预后无死亡及植物生存,入院时GCS 13～14分的患者均恢复工作或学习(GOS5分).在持续有创ICP监测下29例施行了去骨瓣减压术.入院时ICP、去骨瓣减压患者术前ICP和术后ICP恢复良好组分别是(22.2 ±7.9)mm Hg、(31.9±9.5)mm Hg和(12.3 ±2.9)mm Hg;恢复不良组分别是(33.4±18.9) mm Hg、(43.7±14.6)mm Hg和(13.0±5.6) mm Hg.两组指标相对应比较,患者入院时ICP、去骨瓣减压患者术前ICP差异有统计学意义(P＜0.05),去骨瓣减压患者术后ICP差异无统计学意义(P＞0.05).结论 持续有创ICP监测对创伤性急性双侧半球弥漫性脑肿胀的治疗有重要的指导作用,此类患者的预后与入院时ICP、去骨瓣减压患者术前ICP有关.