Statins and cerebral hemodynamics

HMG-CoA reductase inhibitors (statins) are associated with improved stroke outcome. This observation has been attributed in part to the palliative effect of statins on cerebral hemodynamics and cerebral autoregulation (CA), which are mediated mainly through the upregulation of endothelium nitric oxide synthase (eNOS). Several animal studies indicate that statin pretreatment enhances cerebral blood flow after ischemic stroke, although this finding is not further supported in clinical settings. Cerebral vasomotor reactivity, however, is significantly improved after long-term statin administration in most patients with severe small vessel disease, aneurysmal subarachnoid hemorrhage, or impaired baseline CA.     

Music and cerebral hemodynamics.

Previous studies performed by positron emission tomography and Transcranial Doppler (TCD) found a different cerebral activation during musical stimuli in musicians compared to non-musicians. The aim of our study is to evaluate by means of TCD, possible different pattern of cerebral activation during the performance of different musical tasks in musicians, non-musicians and lyrical singers. Our findings show a left hemispheric activation in musicians and a right one in non-musicians. Preliminary data on lyrical singers' activation patterns need further confirmation with a larger population. These data could be related to a different approach to music listening in musicians (analytical) and non-musicians who are supposed to have an emotional approach to music.     

Dolichoectasic anterior cerebral artery and hemodynamics

Dolichoectasia of the intracranial arteries is a rare condition, and the vertebrobasilar system and the internal carotid artery are the most commonly involved structures. We report a rare case of idiopathic dolichoectasia of the anterior cerebral artery in a 22-year-old female. The patient caused an automobile accident and was brought to our hospital in an ambulance. A computed tomography scan and magnetic resonance imaging revealed no fresh lesions, but showed a prominent serpentine structure with calcification and flow void in the region of the interhemispheric fissure, which was suspicious for arteriovenous malformation or arteriovenous fistula. Cerebral angiography demonstrated extensive dilatation of the anterior cerebral artery, but no evidence of arteriovenous malformation or arteriovenous fistula. Single photon emission computed tomography revealed hypoperfusion of the right frontal lobe at rest. Electroencephalography showed no epileptic discharge. The patient's course was uneventful, and she was discharged with no neurologic deficit. There are few reports of hemodynamic changes in cases of dolichoectasia. In the diagnosis of cerebral dolichoectasia, cerebral hemodynamics should be examined carefully in addition to evaluating vascular disease by angiography.     

Sex-related differences in human cerebral hemodynamics

Objectives - Dentatorubral-pallidoluysian atrophy (DRPLA) is a rare autosomal dominant neurodegenerative disorder mostly observed in Japan, rarely reported in American and North European populations. The aim of this study is to characterize the clinical and molecular features of the first identified Italian DRPLA family. Patients and methods - We describe a 33-year-old female presenting with ataxia, intellectual decline, epilepsy, and choreoathetosis with an adult age onset. Genomic DNA was isolated from peripheral blood lymphocytes of the patient and of her healthy family members following standard procedures. Molecular tests were performed including genetic analysis for SCA1, 2, and 3 (spinocerebellar ataxias), Huntington's disease (HD) and DRPLA, due to a possible overlapping in clinical presentation. Results - Molecular analysis revealed in our patient the presence of a pathological CAG expansion within the DRPLA gene. We have also documented the presence of a smaller CAG expansion in her apparently healthy brother, excluding the possibility of a de novo mutation. Conclusion - We conclude that both siblings may have inherited the molecular lesion from their deceased father, the mother being normal at molecular evaluation. Our kindred and a previously reported family from the island of Malta suggest that hereditary DRPLA may also be present in the Mediterranean area.     

Impact of cerebral arteriovenous malformations on systemic and cerebral hemodynamics

Shunt through cerebral arteriovenous malformations (AVMs) causes not only cerebral hemodynamic changes, but also affects the cardiovascular system as a whole. Forty-two patients aged 15 to 62 years were examined. Group 1 included 19 patients with AVM < 20 cm3; Group 2 comprised 23 patients with AVMs > 21 cm3. Cerebral angiography revealed AVMs afferents and stroma. Before and after surgery, total cerebral blood flow was estimated by color duplex scanning of cephalic large arteries; and the heart and systemic hemodynamics were evaluated by ECG, echoECG, and 24-hour blood pressure monitoring. Thus, small AVMs with insignificant arteriovenous shunt do not considerably affect cerebral and systemic hemodynamics (eukinetic hemodynamics). Large AVMs enhance functional load on the cardiovascular system whose hyperfunction as the basic mechanism of cerebral blood flow compensation in arteriovenous shunt through cerebral AVMs is effected by increasing cardiac and stroke, circulating blood volume, blood pressure, and tachycardia. These changes are functional.     

Cerebrovascular hemodynamics in patients with cerebral arteriosclerosis

The present study observed hemodynamic changes in 26 patients with cerebral arteriosclerosis using a cerebral circulation dynamics detector and transcranial Doppler. In patients with cerebral arteriosclerosis the blood supply and flow rate in the bilateral carotid arteries and the blood flow rate in the anterior cerebral and middle cerebral arteries were similar to normal controls, but the cerebral vascular resistance, critical pressure and pulsatility index were increased, and cerebral arterial elasticity and cerebral blood flow autoregulation were decreased. Compared with the le-sioned hemisphere of patients with cerebral infarction, the total blood supply and blood flow rate of patients with cerebral arteriosclerosis were higher. Compared with normal subjects, patients with cerebral arteriosclerosis exhibited cognitive disturbances, mainly in short-term memory, attention, abstract capability, and spatial and executive dysfunction. Results showed that cerebral arteriosclerosis does not directly affect the blood supply of a cerebral hemisphere, but affects cognitive function. The increased cerebral vascular resistance and reduced autoregulation of cerebral blood vessels may be important hemodynamic mechanisms of arteriosclerosis-induced cerebral infarction.     

The abbreviated vigilance task and cerebral hemodynamics

Transcranial Doppler sonography (TCD) and transcranial cerebral oximetry (TCCO) measures of cerebral blood flow velocity and oxygenation levels were collected during an abbreviated 12-min vigilance task. Both the TCD and TCCO measures showed higher levels of cerebral vascular activity in the right than in the left cerebral hemisphere; the cerebral laterality of vigilance occurs in an abbreviated task. Although there was a significant decline in performance over time, there was no significant change in the physiological measures over time during the abbreviated vigil. This latter finding does not match the physiological changes detected in long-duration vigils.     

Regional cerebral hemodynamics in childhood moyamoya disease

Regional cerebral blood flow (rCBF) and its reactivity to acetazolamide were analyzed in a series of 15 cases of childhood moyamoya disease, using the xenon-133 inhalation method and single photon emission CT (SPECT). Most of the patients had normal mean hemispheric cerebral blood flow (mCBF), comparable to that of age-matched healthy children. However, they had abnormal rCBF distribution and disturbed reactivity to acetazolamide in the territory of the internal carotid artery, especially in the frontal lobe. Surgical revascularization for the anterior circulation, which consisted of STA-MCA anastomosis and indirect synangiosis, dramatically improved theses cerebral hemodynamics in the anterior circulation, including the frontal lobe, and reactivity to acetazolamide in the whole brain. These results suggest that surgical revascularization for the anterior circulation should be carried out in order to improve cerebral hemodynamics as widely as possible, especially in the frontal lobe, and may improve cerebral perfusion reserve in the posterior circulation.     

飞行因素对飞行人员脑血流动力学变化的影响

目的 对比分析飞行员和健康志愿者的动态脑血流动力学特征,探讨飞行因素对脑血流动力学特征的影响.方法 采用多普勒超声技术分别观察飞行员（n=99）和健康志愿者（n=99）大脑前、中、后动脉,椎动脉及基底动脉的收缩期峰值（systolic velocity,Vs）,舒张期流速（diastolic velocity,Vd）,平均血流速度（mean velocity,Vm）,血管搏动指数（pulsitility index,PI）.结果 与健康志愿者比较,飞行员的左侧椎动脉（颅内段）Vm （34.77±8.40,32.60±6.20;P=0.038）降低.结论 飞行因素可以导致飞行人员左侧椎动脉流速的降低,可能会进一步诱发眩晕等症状.     

Normal human sleep: Regional cerebral hemodynamics

Measurements of regional cerebral blood flow (rCBF) by the xenon 133 inhalation method along with polygraph recordings were made serially during relaxed wakefulness and different stages of nocturnal sleep in 18 righthanded normal volunteers. During stage I-II sleep the fast flow (Fg) values declined significantly, more in the brainstem-cerebellar (BSC) regions than in hemispheric regions. During stage III-IV sleep, Fg further declined diffusely in both hemispheric (-28%) and BSC (-29%) regions. Duringg awakening from stage IV sleep to alpha-frequency wakefulness, BSC flow values increased more than hemispheric flow values. During REM sleep, regional Fg values increased diffusely in both hemispheric (+41%) and BSC (+47%) regions compared with wakefulness. There was a significant inverse correlation between the increase in end-tidal partial pressure for carbon dioxide and the reduction in bihemispheric Fg during sleep. Cerebral vasomotor responsiveness to carbon dioxide is decreased during both REM and non-REM sleep.     

Systemic and cerebral hemodynamics during cognitive testing

Objective  

Cognitive deficits are reported in 10–60% of individuals with SCI, the primary etiology of these deficits is believed to be concomitant traumatic brain injury (TBI). We recently documented diminished memory and marginally deficient attention and processing speed in individuals with SCI discordant for hypotension but matched for TBI.     

Effect of chronic middle cerebral artery stenosis on the local cerebral hemodynamics

In 36 patients with angiographically proven middle cerebral artery (MCA) stenosis, local cerebral hemodynamics were studied employing angiography, 133Xe inhalation regional cerebral blood flow (rCBF) measurements and CT scans. They had transient ischemic attacks in 8 and completed stroke in 28. The patients with less than 50% stenosis (n = 16) had no hemodynamic abnormality in angiographical and rCBF examinations. The infarction in this group was small and located in the basal ganglia area. The patients with 50 to 74% stenosis (n = 9) often revealed a delayed filling of MCA branches in the angiography, however, they showed no significant rCBF reduction. The infarction in this group was also small and located in the basal ganglia area. The patients with 75 to 99% stenosis (n = 11) exhibited a significant flow depression both in angiographical and rCBF examinations. Three of them had large cerebral infarction in the watershed zone or the cerebral cortex. The results of the present study suggest that the hemodynamic effect of MCA stenosis begins to manifest at 50% in grade and becomes apparent at 75%. The danger of hemodynamic crisis as well as the risk of large cerebral infarction may increase when MCA stenosis exceeds 75% in grade.     

Evaluation of cerebral hemodynamics with perfusion CT]

We report on the evaluation of cerebral ischemic lesions with perfusion CT. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) of 52 patients mostly with ischemic cerebrovascular disease were analysed using the box-modulation transfer function method with 30 ml of contrast medium intravenously injected at 5 ml/sec. CBF, CBV and MTT of the middle cerebral artery (MCA) territory were 43.5 +/- 4.6 ml/100 g/min, 1.9 +/- 0.2 ml/100 g and 2.9 +/- 0.6 seconds at the unaffected side, and 37.7 +/- 7.3 ml/100 g/min, 2.1 +/- 0.3 ml/100 g, 3.7 +/- 0.9 seconds at the lesion side with stenosis or occlusion in the main MCA trunks or internal carotid artery, respectively. A statistically significant difference was shown in CBF and MTT values. Furthermore, there was a close correlation in CBF values of MCA territories between Xe-CT and perfusion CT (r = 0.645, n = 76, p < 0.0001). MTT showed a positive correlation with CBV in those subjects when MTT was below 4.1 seconds (r = 0.526, p < 0.0001, n = 83). MTT also showed a negative correlation with CBF in those patients when MTT indicated more than 4.1 seconds (r = 0.818, p < 0.001, n = 21). These results suggest that the progression of cerebral ischemia may be classified in 4 stages using perfusion CT. The stages are as follows: stage 0; normal CBF without prolonged MTT and increased CBV, stage 1; relatively increased CBV, stage 2; significantly prolonged MTT, and stage 3; significantly decreased CBF with prolonged MTT.     

Changes in cerebral hemodynamics during laparoscopic cholecystectomy.

Laparoscopic surgery requires a series of procedures, including intraperitoneal CO2 insufflation, which can cause cardiovascular and hemogasanalytic modifications, potentially able to impair cerebral perfusion. The aim of this study was to evaluate changes in cerebral blood flow velocity during laparoscopic cholecystectomy. Eighteen patients undergoing laparoscopic cholecystectomy were studied. Middle cerebral artery blood flow velocity was monitored using transcranial Doppler ultrasonography. Electrical bioimpedance was employed to measure cardiac output, stroke volume and to calculate derived parameters. End-tidal CO2, mean arterial blood pressure, end expiratory anesthetic concentration and O2 saturation were monitored non-invasively. Cerebral artery blood flow velocity increased significantly after CO2 insufflation (p < 0.05) and remained stable. The highest values were reached after CO2 desufflation. A significant reduction in stroke volume and cardiac output (p < 0.05) associated with increased vascular systemic resistances (p < 0.001) was observed soon after CO2 insufflation. The decrease in cardiac output and the increase in vascular systemic resistances remained significant throughout abdominal insufflation. Heart rate and mean arterial pressure remained substantially unchanged with the exception of a significant decrease (p < 0.001) before CO2 insufflation. There was no significant change in end-tidal CO2 during abdominal insufflation. These findings suggest that the cerebrovascular system can undergo adaptive changes during all phases of laparoscopic surgery. However, the extent of cardio- and cerebrovascular variation indicates the need for careful preliminary evaluation of cerebral hemodynamics in patients with vascular disorders before laparoscopic surgery.     

轻度认知障碍患者的脑血流动力学临床研究

目的通过经颅多普勒(Transcranial Doppler,TCD)结合事件相关电位(Event-related potentials,ERP)对轻度认知障碍(Mild cognitive impairment,MCI)患者的脑血流动力学特点进行综合评价。方法180例受试者根据ERP和TCD检测结果,编入正常对照组、MCI组及痴呆组,统计分析不同认知功能状态下脑血流动力学的特点。结果各组别受试者脑动脉硬化及血管狭窄检出率有差异,正常组与MCI组及痴呆组比较,Vp、Vm、S/D及PI有统计学意义(P<0.01);MCI组与痴呆组比较,Vp和S/D均有统计学意义(P<0.05);TCD的Vp及S/D对ERP中P3潜伏期影响较大(P<0.01)。结论脑血流动力学的改变对MCI患者的认知功能有明显影响,脑血流动力学TCD检测结果可以作为评判MCI患者认知状态的客观指标。     

Abnormal cerebral hemodynamics during attacks of alternating hemiplegia

Frequent episodes of bilateral weakness and apathy, followed later by hemiplegia of alternating sides were observed in a now 32-month-old girl. Transcranial Doppler ultrasonography showed reduced flow velocities in the middle cerebral artery of the affected side during a hemiplegic attack and increased flow velocities at different sites of the basilar artery during a bilateral episode. These abnormal cerebral hemodynamics appear to indicate that alternating hemiplegia and some forms of migraine have a similar pathophysiology.     

The cerebral hemodynamics of repetitive transcranial magnetic stimulation

Repetitive transcranial magnetic stimulation (rTMS) has been shown to be effective in the treatment of affective disorders. However, only little is known about hemodynamic physiological and safety aspects of this method. We studied the cerebral hemodynamics as measured by transcranial Doppler sonography in 20 healthy subjects during different rTMS procedures. Mean cerebral blood flow velocity (CBFBV), pulsatility index (PI), and oxygen consumption were recorded continuously and averaged directly after the rTMS procedure. RTMS did not influence blood pressure, pulse rate, or blood oxygenation. There was a maximal increase of CBFV in the middle cerebal artery (MCA) of 3.6% and 5.6% during 10 Hz and 20 Hz stimulation, respectively. This increase was only seen on the stimulated left hemisphere. The PI remained unchanged during the whole procedure. It is likely that the increase of CBFV is due to dilatation of the small resistance vessels rather than due to vasoconstriction of the MCA. In terms of cerebral hemodynamics, rTMS is a safe and well-tolerated technique with a lower increase of CBFV than that seen in electroconvulsive therapy. Received: 22 March 2000 / Accepted: 4 July 2000     

Effects of midazolam on cerebral hemodynamics and cerebral vasomotor responsiveness to carbon dioxide

Although it is known that hypercarbia increases and benzodiazepines decrease cerebral blood flow (CBF), the effects of benzodiazepines on CBF responsiveness to CO2 are not well documented. The influence on CBF and CBF-CO2 sensitivity of placebo or midazolam, which is a new water-soluble benzodiazepine, was measured in eight healthy volunteers using the noninvasive 133Xe inhalation method for CBF determination. Under normocarbia, midazolam decreased CBF from 40.6 +/- 3.2 to 27.0 +/- 5.0 ml 100 g-1 min-1 (means +/- SD). At a later session under hypercarbia, CBF was 58.8 +/- 4.4 ml 100 g-1 min-1 after administration of placebo, and 49.1 +/- 10.2 ml 100 g-1 min-1 after midazolam. The mean of the slopes correlating PaCO2 and CBF was significantly steeper with midazolam (2.5 +/- 1.2 ml 100 g-1 min-1 mm Hg-1) than with placebo (1.5 +/- 0.4 ml 100 g-1 min-1 mm Hg-1). Our results suggest that midazolam may be a safe agent to use in patients with intracranial hypertension, since it decreases CBF and thus cerebral blood volume; however, it should be administered with caution in nonventilated patients with increased intracranial pressure, since its beneficial effects on cerebrovascular tone can be readily counteracted by the increase in arterial CO2 tension induced by this drug.     

Emotion-related cerebral asymmetry: hemodynamics measured by functional ultrasound

This study assessed the use of transcranial Doppler ultrasound in detecting selective changes in cerebral blood flow velocity during emotional processes. The role of the respective hemispheres in emotional processing is controversial. Cerebral control of emotional processing has previously been investigated by analysis of patients with unilateral brain damage, experiments with selective stimulation of only one hemisphere, and more recently by imaging techniques measuring local cerebral blood flow. We investigated mean flow velocity continuously and simultaneously in both the right and left middle cerebral arteries (MCAs) in 16 healthy right-handed young subjects at rest and during the performance of three tasks: task 1: 15 slides with nonemotional content; task 2: 15 slides with negative emotional content; task 3: 15 slides with nonemotional content with different content from that in task 1. The three tasks produced significantly different effects on the right and left hemispheres. During the two nonemotional tasks the increase in mean flow velocity over basal values was similar in the two MCAs (task 1: left MCA = 3.27 ± 1.9%; right MCA = 3.63 ± 2.1%; task 3: left MCA = 2.42 ± 0.7%; right MCA = 2.56 ± 1.3%); the negative emotional task was accompanied by a significantly higher increase in the right (11.31 ± 1.6%) than in the left MCA (4.72 ± 3.7%; analysis of variance two-way interaction: side of recording x task, F = 43.6, P < 0.001). These results show the possibility of obtaining specific functional information from bilateral transcranial Doppler ultrasound and suggest the involvement of the right hemisphere in emotional processing. Received: 4 March 1999 Received in revised form: 29 June 1999 Accepted: 5 August 1999