Quantitative measurement of cerebral blood flow and cerebral blood volume after cerebral ischaemia

CBF obtained by the hydrogen clearance technique and cerebral blood volume (CBV) calculated from the [14C]dextran space were measured in three groups of rats subjected to temporary four-vessel occlusion to produce 15 min of ischaemia, followed by 60 min of reperfusion. In the control animals, mean CBF was 93 +/- 6 ml 100 g-1 min-1, which fell to 5.5 +/- 0.5 ml 100 g-1 min-1 during ischaemia. There was a marked early postischaemic hyperaemia (262 +/- 18 ml 100 g-1 min-1), but 1 h after the onset of ischaemia, there was a significant hypoperfusion (51 +/- 3 ml 100 g-1 min-1). Mean cortical dextran space was 1.58 +/- 0.09 ml 100 g-1 prior to ischaemia. Early in reperfusion there was a significant increase in CBV (1.85 +/- 0.24 ml 100 g-1) with a decrease during the period of hypoperfusion (1.33 +/- 0.03 ml 100 g-1). Therefore, following a period of temporary ischaemia, there are commensurate changes in CBF and CBV, and alterations in the permeability-surface area product at this time may be due to variations in surface area and not necessarily permeability.     

颅脑损伤后炎症反应与脑水肿

创伤性脑水肿是创伤性脑损伤（traumatic brain iniury，TBI）后的主要继发性病理生理过程之一，也是导致颅内压增高的主要原因。目前国内外多数学者主张将脑水肿分为血管源性、细胞毒性、渗透压性和脑积水性（间质性）四类。过去几十年，根据冷冻性脑损伤模型的研究结果，普遍认为创伤性脑水肿以血脑屏障（BBB）破坏后的血管源性脑水肿为主。但新近研究发现，创伤性脑水肿是血管源性和细胞毒性的混合性水肿，并且以细胞毒性脑水肿为主。[第一段]     

Regional cerebral blood flow correlates of aphasia outcome in cerebral hemorrhage and cerebral infarction

The relationship between recovery from aphasia and regional cerebral blood flow (CBF) was compared in 87 patients, 44 with cerebral hemorrhage and 43 with non-embolic cerebral infarction. CBF values correlated poorly with aphasia outcome in patients with cerebral hemorrhage whereas a tight correlation was demonstrated in patients with non-embolic cerebral infarction. A marked variability of CBF values in the acute and subacute stage might account for the poor correlation between CBF and aphasia outcome in patients with cerebral hemorrhage. On the other hand, a sharp discrimination was achieved between those with a good recovery from aphasia and those with a poor recovery by the dimensions of the hematoma on CT. In non-embolic cerebral infarction, a relative frontal ischemia was associated with motor aphasia while a relative temporal ischemia was associated with sensory aphasia. This dichotomy was not demonstrated in the regional CBF values in patients with cerebral hemorrhage.     

Effects of ATP on cerebral circulation--morphological observation of cerebral circulation and cerebral vasculature]

Review was made on the effect of adenosine triphosphate, 1.0-3.0 mg/kg intravenously, on the cerebral circulation and the presence of the dilating action on the cerebral blood-vessels in cats. 1. The group of the normal intra-cranial pressure showed, as reported previously, the transient hypotension and its complicated decrease of cerebral blood-circulation at the initial period for 30-100 check, then demonstrating the increase of cerebral blood-flow for 200-1000 check. Its increased volume and duration were dose-dependent. 2. The group of the loaded intracranial pressure of 20-30 mmHg (slightly elevated group) showed the increase of cerebral blood-flow, like the group of the normal intracranial pressure. However, the effect of ATP showed the decrease or disappearance in accordance with the elevation of the loaded pressure. 3. Cerebral vasodilating effect of ATP was promptly observed after the administration, and its degree was 30-50% in photographical observation. 4. Increasing effect on cerebral blood-flow and cerebral vasodilating action of ATP were similar in the pattern to that of vasodilators such as papaverine hydrochloride.     

貌似脑瘤的脑型血吸虫病15例临床分析

目的 探讨脑瘤型脑血吸虫病的临床及MRI的特点.方法 对收治的15例脑瘤型脑血吸虫病的临床资料、实验室检查及MRI资料进行回顾性分析.结果 均为慢性脑型血吸虫病肉芽肿型,表现为脑瘤型.脑瘤型脑血吸虫病的MRI表现具有特征性.结论 脑瘤型脑血吸虫病的MRI易误诊为肿瘤,应结合实验室及影像学检查综合分析.     

The effects of naloxone on cerebral blood flow and cerebral function during relative cerebral ischemia

CBF and somatosensory evoked potentials (SEPs) were measured in a model of moderate cerebral ischemia in anesthetized spontaneously hypertensive rats. The rats were bled to reduce SEP amplitudes to about 50% of prebleeding control. The consequent blood pressure fall reduced CBF to 77% of control as measured by the laser-Doppler technique. Naloxone (5 mg kg-1 i.v. plus 25 mg kg-1 h-1 i.v. for 30 min) caused a significant increase in SEP amplitudes, while CBF did not change significantly. In addition, the latency of the first SEP component decreased toward prebleeding values. Heart rate (HR) decreased, but MABP was held constant by a pressure-regulating reservoir. In unbled rats, naloxone (5 mg kg-1 i.v.) caused a transient small increase in MABP and SEP amplitudes and decrease in HR. These results indicate that sensory input is regulated by opioid systems. Increased opioid activity may inhibit ascending sensory pathways during relative cerebral ischemia and thereby depress SEP responses. Thus, naloxone can release this inhibition and enhances SEP independently of CBF during relative cerebral ischemia. Similar mechanisms might explain the apparently beneficial effects of naloxone in some stroke models.     

Posterior cerebral artery infarction from middle cerebral artery infarction

BACKGROUND: While it is known that posterior cerebral artery (PCA) infarction may simulate middle cerebral artery (MCA) infarction, the frequency and localization of this occurrence are unknown. OBJECTIVE: To determine the frequency of PCA infarction mimicking MCA infarction and the territory of the PCA most commonly involved in this simulation. DESIGN: We studied 202 patients with isolated infarction in the PCA admitted to our stroke center to determine the frequency of PCA infarction simulating MCA infarction, the involved PCA territory, and the patterns of clinical presentation. RESULTS: We found 36 patients (17.8%) with PCA ischemic stroke who had clinical features suggesting MCA stroke. The PCA territory most commonly involved was the superficial PCA territory (66.7%), followed by the proximal PCA territory (16.7%) and both the proximal and the superficial PCA territories (16.7%). The principal stroke mechanism was cardioembolic (54.1%) in the superficial PCA territory, lacunar (46.2%) in the proximal PCA territory, and undetermined (40.2%) in both the proximal and the superficial territories. Among the 36 patients, the most common clinical associations were aphasia (13 patients), visuospatial neglect (13 patients), and severe hemiparesis (7 patients). CONCLUSIONS: Posterior cerebral artery infarction simulating MCA infarction is more common than previously thought. Early recognition of the different stroke subtypes in these 2 arteries may allow specific management.     

重症脑梗死脑血流动力学的动态观察

目的:动态观察重症脑梗死脑血流动力学变化的特征和规律。方法:对42例急性重症脑梗死患者进行连续7天的TCD检测,20例正常人TCD检测数据作为正常组。结果:急性重症脑梗死患者脑血流速度减慢。血管阻力参数值(Pl、Rl)增大,病程的3～5天各指标变化达高峰。结论:根据脑血流动力学的特征性改变,表明重症脑梗死在病程早期就有不同程度的缺血性脑水肿发生,进展迅速,多在病程的3—5天达高峰:TCD用于床旁连续监测,可通过动态观察TCD参数变化,评价颅内压变化、判断预后。     

Familial cerebral amyloid angiopathy presenting as recurrent cerebral haemorrhage

Eleven patients belonging to two generations of a Dutch family with cerebral and cerebellar haemorrhage, haemorrhagic infarction and infarction are described. Their ages varied from 44 to 58 years. The principal clinical characteristic was recurring cerebral haemorrhages, sometimes preceded by a history of migrainous headaches or mental changes.In 4 of the 6 autopsied cases, old and new multiple cerebral haemorrhagic infarcts and infarcts were found, in one case a single cerebral haemorrhage and in another a cerebellar haemorrhage. In 5 cases this resulted in secondary subarachnoid haemorrhage. In one case the infarcts were only slightly haemorrhagic and did not result in subarachnoid haemorrhage. This patient presented as dementia.Microscopically, in these 6 cases and in one biopsy specimen hyaline thickening of the walls of cortical arterioles was found. The arteries of the arachnoid showed marked tortuosity, concentric proliferation, and focal hyalinization of the walls. Amyloid was found in the hyalinized vessels in 5 cases, but not outside the central nervous system.We believe that we are dealing with an inherited disorder with an autosomal dominant mode of inheritance, in which microangiopathy leads to cerebral haemorrhage and (haemorrhagic) infarction. It seems likely that amyloidosis underlies the angiopathy, and that this family suffers from a condition similar to the one described by Gudmundsson in 1972.     

Gene therapy for cerebral infarction (cerebral ischemia)]

The treatment strategies of cerebral infarction have been studied in order to prevent neuronal cell death. Gene therapy is one of the most promising therapy and has several advantage over classical drug therapies. There has been a problem that drug proteins are unable or difficult to pass through blood brain barrier. In gene therapy, however, drug proteins are expressed in the brain with transgene transfer technique. Ischemic neural death proceeds with a complex series of pathophysiological events in the neurons. But molecular mechanism of ischemic neuronal cell death gradually understood. It has been known that a number of genes can be potent candidates for treatment factors of cerebral infarction. Actually, many investigators have been studied treatment strategies of cerebral infarction using a variety of neurotrophic factors such as bcl-2, heat shock protein 72, glial cell line-derived neurotrophic factor (GDNF), and hepatocyte growth factor (HGF). Moreover, the development of new vectors and gene delivery systems have been studied. Gene therapy would be a strong strategy for treatment of cerebral infarction in the future.     

脑梗塞后出血的临床病理研究

观察脑梗塞后出血脑组织的病理变化。方法在４４例脑梗塞尸检病例中，选出１７例肉眼可见的梗塞后出血，对其进行临床分析和病理观察。结果毛细血管型出血１１例，发生在皮层附近，出血灶散在呈片状，为漏出性或破裂性出血，发病晚，支持血液再灌注论点。小动脉型出血６例，发生在基底节附近，出血量大，为破裂性出血。结论梗塞后出血多发生于靠近大脑皮层的大、中等面积脑梗塞之后。发病时间的早晚、临床症状的轻重和预后与再出血的血管有关，与再出血的量呈正相关。     

Impaired dynamic cerebral autoregulation in middle cerebral artery stenosis

Abstract

Background and purpose: Analysis of dynamic cerebral autoregulation during transient falls in blood pressure is considered a sensitive and convenient method for evaluating patients with carotid artery stenosis. To this point, there have been few reports on the efficacy of using the thigh cuffs technique to analyse middle cerebral artery (MCA) stenosis. If it could be determined whether cerebral blood flow can be maintained (autoregulated) during sudden falls in arterial blood pressure (ABP), then it might be possible to identify patients with MCA stenosis who are at risk of stroke.

Methods: We used the thigh cuff technique to estimate dynamic cerebral autoregulation in 57 patients with MCA stenosis and 72 normal controls. After a stepwise fall in arterial blood pressure, we determined the rate of the rise of MCA blood velocity and compared it with the rate of the rise of arterial blood pressure. In this manner, the dynamic cerbral autoregulation of 11 patients undergoing MCA M1 stent angioplasty was estimated both pre- and post-operation.

Results: The autoregulatory index (ARI) was significantly reduced in patients with stenosed/occluded MCA (3.24 ± 1.52), as compared with normal controls (5.25 ± 1.39; p<0.001) (results reported as mean ± SD). Poor ARI values are usually observed in patients with a higher degree of stenosis and particularly in patients with insufficient collateral compensation. ARI was significantly reduced in severe stroke patients (modified ranking scale≥1), as compared with asymptomatic or TIA patients (p<0.05). After MCA stent angioplasty was performed, there was a significant improvement in ARI in 11 subjects, which caused a mean increase in ARI from 2.08 ± 1.10 to 3.80 ± 1.36 (p=0.008).

Conclusions: Dynamic cerebral autoregulation is impaired in patients with middle cerebral artery stenosis. Assessing dynamic cerebral autoregulation may allow a subgroup of patients with MCA stenosis who are at risk of hemodynamic stroke to be identified. Dynamic cerebral disautoregulation in patients with severe MCA stenosis is mostly remedied by stent angioplasty.