术中多普勒微探头超声在复杂动脉瘤血管架桥及重建手术中的应用(附15例分析)

目的研究术中多普勒微探头超声在复杂动脉瘤血管架桥及重建手术中的应用。方法回顾性分析15例动脉瘤病人行动脉瘤血管架桥及重建手术的经验。术中分别在血管架桥及重建手术前后进行吻合血管和移植血管血流的检测,并在孤立动脉瘤后对动脉瘤及载瘤动脉进行血流检测。结果在血管架桥及孤立动脉瘤后,多普勒检测显示本组动脉瘤内血流均消失,移植血管通畅。结论在动脉瘤血管架桥及重建手术中,术中多普勒微探头超声是一种简便、安全有效的监测技术。     

Laser speckle imaging allows real-time intraoperative blood flow assessment during neurosurgical procedures

Currently, there is no adequate technique for intraoperative monitoring of cerebral blood flow (CBF). To evaluate laser speckle imaging (LSI) for assessment of relative CBF, LSI was performed in 30 patients who underwent direct surgical revascularization for treatment of arteriosclerotic cerebrovascular disease (ACVD), Moyamoya disease (MMD), or giant aneurysms, and in 8 control patients who underwent intracranial surgery for reasons other than hemodynamic compromise. The applicability and sensitivity of LSI was investigated through baseline perfusion and CO₂ reactivity testing. The dynamics of LSI were assessed during bypass test occlusion and flow initiation procedures. Laser speckle imaging permitted robust (pseudo-) quantitative assessment of relative microcirculatory flow and standard bypass grafting resulted in significantly higher postoperative baseline perfusion values in ACVD and MMD. The applicability and sensitivity of LSI was shown by a significantly reduced CO₂ reactivity in ACVD (9.6±9%) and MMD (8.5±8%) compared with control (31.2±5% P<0.0001). In high- and intermediate-flow bypass patients, LSI was characterized by a dynamic real-time response to acute perfusion changes and ultimately confirmed a sufficient flow substitution through the bypass graft. Thus, LSI can be used for sensitive and continuous, non-invasive real-time visualization and measurement of relative cortical CBF in excellent spatial–temporal resolution.     

颈髓电刺激增加脑血流的作用机制研究(英文)

目的尽管颈髓电刺激(SCS)在许多动物实验中已被证实能增加脑血流,但其作用机理还不甚明了。本文将从脑血管的交感和副交感通路方面探讨SCS对脑血流的影响机理。方法对SD大鼠给予SCS并用激光多普勒(LDF)实时记录脑血流。动物分成5 组,对照组:不对神经纤维和神经节作任何手术处理;V1 组:切断双侧鼻睫状神经及其副交感节后纤维;SCS组:切断双侧颈上神经节;V1 SCG:切断双侧鼻睫状神经及其副交感节后纤维及双侧颈上神经节;假手术组:手术暴露双侧鼻睫状神经和其副交感节后纤维及双侧颈上神经节,但不切断神经纤维或神经节。结果SCS时的LDF变化在对照组、V1和SCG 组间没有显著性差异。但在V1 SCG组中,SCS的升脑血流效应却被明显抑制了。结论SCS的升脑血流效应可能是通过交感和副交感双重通路实现的。     

颈髓电刺激增加脑血流的作用机制研究

目的 尽管颈髓电刺激（SCS）在许多动物实验中已被证实能增加脑血流,但其作用机理还不甚明了。本文将从脑血管的交感和副交感通路方面探讨SCS对脑血流的影响机理。方法 对SD大鼠给予SCS并用激光多普勒（LDF）实时记录脑血流。动物分成5组,对照组：不对神经纤维和神经节作任何手术处理;V1组：切断双侧鼻睫状神经及其副交感节后纤维;SCS组：切断双侧颈上神经节;V1＋SCG：切断双侧鼻睫状神经及其副交感节后纤维及双侧颈上神经节;假手术组：手术暴露双侧鼻睫状神经和其副交感节后纤维及双侧颈上神经节,但不切断神经纤维或神经节。结果 SCS时的LDF变化在对照组、V1和SCG组间没有显著性差异。但在V1＋SCG组中,SCS的升脑血流效应却被明显抑制了。结论 SCS的升脑血流效应可能是通过交感和副交感双重通路实现的。     

Cerebral perfusion in the elderly with nocturnal blood pressure fall

Cerebrovascular disease may be linked with vascular autoregulation in aging. The aim of this study was to examine relation between nocturnal blood pressure (BP) fall and cerebral blood flow (CBF) changes in elderly men. The prospective 'Men born in 1914' cohort study has been in progress since 1968 and included 809 subjects. After 14 years from the last follow up, 97 subjects reached the age of 82 and underwent CBF measurement and 24 h ambulatory blood pressure monitoring. Diastolic BP at night decreased in 84 subjects with median 12.7% and increased in 13 subjects with median 3.7%. Relative diastolic BP fall at night was negatively associated to CBF in temporal and infero-parietal areas. Higher proportion of subjects with increasing systolic BP during the 14-year period was observed in the subgroup with extreme nocturnal diastolic BP dip, irrespectively of BP values or prevalence of hypertension. Extreme nocturnal diastolic BP fall in a cohort of elderly men is correlated with focal changes in CBF. Further studies could explain if increasing BP in the elderly is a cause or result of pathological autoregulation, and if antihypertensive treatment increases nocturnal BP dip.     

Lipid-sugar particles for intracranial drug delivery: safety and biocompatibility

Controlled release of drugs to specific locales in the brain has engendered considerable interest. Here we evaluate the safety and biocompatibility of 6-microm diameter particles composed of dipalmitoylphosphatidylcholine and chondroitin sulfate A, when delivered into the cerebral parenchyma and ventricles, and in the case of intravascular injection. Some particles were loaded with fluorescein-labeled albumin to facilitate detection. Particles placed in medium with cultured murine primary cortical neurons did not increase cell death at concentrations as high as 4 mg/ml. When particles (100 microg in 2 microl) were placed stereotactically in the striatum and lateral ventricles, there was no histological evidence on hematoxylin-eosin stained sections of tissue injury outside of the needle track in any animal 3, 7, and 14 days after injection (n=6 each), and no inflammation. Ventricular size was not significantly different between animals given intraventricular injections of particles and albumin solution at those time points (n=4 each). Intracarotid injection of particles at concentrations of 0.2 and 1 mg/ml (n=4 each) did not affect relative cerebral blood flow, and there were no embolic events on histology. In one animal in the group injected with 5 mg/ml (n=3), there was a profound decrease in rCBF, with patchy emboli on histology. These novel biodegradable particles are biocompatible in and around the brain, and may be safe for intracranial sustained drug delivery either in the parenchyma or into the CSF.     

Effect of stimulation of the dorsal aspect of the cervical spinal cord on ’Iocal cerebral blood flow and EEG in the cat

Abstract

Currently there is considerable interest in electrical stimulation of the dorsal aspect of the cervical spinal cord as a potentially effective therapy for persistent vegetative patients. The authors assessed change in the local cerebral blood flow (LCBF) and electroencephalogram (EEe) in the cat following spinal cord stimulation (SCS). In 31 adult cats under isoflurane anesthesia, an electrode for SCS was introduced epidurally to the midline of the C2-C3 segment. Stimulation was performed at 25 Hz and 0.7 msec for30 min. These animals were divided into five groups by the voltage: (1) 2V (n = 7), (2) 4V (n = 7), (3) 6V (n = 7), (4) 4V with intravenous injection of muscarinic cholinergic agents - atropine sulfate (n =5), and (5) sham-operated control (n = 5) without stimulation. LCBF was measured by laser Doppler flowmetry through bilateral small burr holes at the parietal area during and 60 min after stimulation. At 2~ LCBF increased only during SCSI then returned to the pre-stimulated level, while the increase continued until the end of the experiment at 4Vand 6V. The increase in LCBF was not affected by atropine sulfate. EEe showed spike and wave or polyspikes after SCS in two animals of the 6V group, but not in the 2V and 4V groups, and moreover a moderate increase ofthe background activity at only 4V. The present data suggested that SCS at 4Vcan provide the appropriate microcirculatory enhancement with less harmful influence which continues to increase 30 min after SCSI although the exact mechanism should be elucidated continuously. Within the limitation of animal experiments, this study could provide the logical basis for determining the condition of SCS. [Neural Res 2000; 22: 386-392]     

Cerebral blood flow and cerebral hematocrit in patients with cerebral ischemia measured by single-photon emission computed tomography

Abstract– Single-photon emission computed tomography (SPECT) was used for the measurement of regional cerebral blood flow (CBF), cerebral blood volume (CBV) and cerebral hematocrit (Hct). CBF was measured using N-isopropyl-p-I-123-Iodoamphetamine. CBV was measured by both RBC tracer (Tc-99m RBC) and plasma tracer (Tc-99m human serum albumin) and cerebral hematocrit (Hct) was calculated. In normals, the cerebral-to-large vessel Hct ratio was 75.9%. Isovolemic hemodilution in patients with high Hct tended to increase the cerebral-to-large vessel Hct ratio. Low CBF, high CBV and slow cerebral blood mean transit time (MTT by dynamic CT scanning) was seen during the acute stage of completed infarction and during the symptom-free interval of TIA. Cerebral Hct was increased in the ischemic region of poor prognosis.     

Cerebral pressure–flow relationship in lowlanders and natives at high altitude

We investigated if dynamic cerebral pressure–flow relationships in lowlanders are altered at high altitude (HA), differ in HA natives and after return to sea level (SL). Lowlanders were tested at SL (n=16), arrival to 5,050 m, after 2-week acclimatization (with and without end-tidal PO₂ normalization), and upon SL return. High-altitude natives (n=16) were tested at 5,050 m. Testing sessions involved resting spontaneous and driven (squat–stand maneuvers at very low (VLF, 0.05 Hz) and low (LF, 0.10 Hz) frequencies) measures to maximize blood pressure (BP) variability and improve assessment of the pressure–flow relationship using transfer function analysis (TFA). Blood flow velocity was assessed in the middle (MCAv) and posterior (PCAv) cerebral arteries. Spontaneous VLF and LF phases were reduced and coherence was elevated with acclimatization to HA (P<0.05), indicating impaired pressure–flow coupling. However, when BP was driven, both the frequency- and time-domain metrics were unaltered and comparable with HA natives. Acute mountain sickness was unrelated to TFA metrics. In conclusion, the driven cerebral pressure–flow relationship (in both frequency and time domains) is unaltered at 5,050 m in lowlanders and HA natives. Our findings indicate that spontaneous changes in TFA metrics do not necessarily reflect physiologically important alterations in the capacity of the brain to regulate BP.     

Cerebral extracellular lactate concentration and blood flow during chemical stimulation of the nucleus tractus solitarii in anesthetized rats

The extracellular lactate concentration and blood flow in the cerebral cortex of urethane-anesthetized, paralyzed and artificially ventilated rats were monitored continuously and simultaneously using an enzyme electrode and a laser Doppler flowmeter (LDF), respectively, during chemical stimulation of the nucleus tractus solitarii (NTS) by microinjection of -glutamate (1.7 nmol 50 nl). Chemical stimulation of the NTS significantly decreased the arterial blood pressure (ABP) from 85 ± 17 to 68 ± 14 mmHg, heart rate from 418 ± 13 to 402 ± 19 beats · min⁻¹ and cerebral blood flow (CBF) by 17.9 ± 6.2% (P < 0.001). However, chemical stimulation of the NTS significantly increased the lactate concentration by 58.9 ± 17.3 μM (P < 0.001). Barostat maneuver, which held systemic ABP constant during chemical stimulation of the NTS attenuated the responses in CBF and lactate concentration by 30 and 27%, respectively. The onset of the increase in lactate concentration was delayed about 19 s after that of the CBF decrease. Circulatory lactate produced no significant change in the cerebral extracellular lactate concentration. These results indicate that chemical stimulation of the NTS induces an increase in extracellular lactate concentration in the cerebral cortex through a decrease in CBF via cerebral vasoconstriction.     

Psychopathological and SPECT findings in never-treated schizophrenia

A total of 24 never-treated (i.e. drug-naive) actively psychotic schizophrenic patients, operationalized according to DSM-III-R, were examined in a pre-post-treatment design using the Positive and Negative Syndrome Scale for Schizophrenia (PANSS) and ^99mTc-HMPAO-single photon emission computed tomography (SPECT) to assess regional cerebral blood flow (rCBF). The control subjects were 20 patients free of neurological and psychiatric symptoms. Before treatment there was only a slight hypofrontality, and hypoperfusion was observed in the left temporal superior region. After treatment, hypofrontality was reduced to one region and temporal hypoperfusion disappeared. Formal thought disorders were accompanied by increased rCBF in the bilateral frontal interior and left temporal superior regions. Delusions were associated with hypoperfusion in the anterior cingulate cortex. Negative symptoms showed no linkage to hypofrontality, either before or after treatment. Factor analysis showed delusions and hallucinations loading on different dimensions. The disorganized dimension correlated positively with all regions of interest, whereas these were negatively correlated with reality distortion.     

The effect of ACTH on cerebral blood flow in children with intractable epilepsy

Cerebral blood flow was assessed by ultrasound in 12 children with intractable epilepsy who were treated with ACTH. The average maximal blood velocity (A/L) and end-diastolic blood velocity (d) of the internal carotid artery were measured, before, during and after ACTH therapy in each subject. The right and left mean A/L and d values were significantly decreased during ACTH therapy, and these values returned to the previous levels after the treatment. Cerebral function in children treated with ACTH may be affected by a decrease in cerebral blood flow.     

床突旁动脉瘤术中吲哚菁绿脑血管造影的应用(附5例报告)

目的探讨吲哚菁绿（indocyanine green，ICG）脑血管造影在床突旁动脉瘤手术中的作用。方法回顾性分析2007年6月，8月手术治疗的5例床突旁动脉瘤，4例采用同侧翼点人路夹闭动脉瘤，另1例左侧颈内动脉一垂体上动脉瘤伴对侧后交通动脉瘤病人行右侧翼点人路夹闭双侧动脉瘤。术中动脉瘤夹闭后行ICG脑血管造影4例，夹闭前后均行ICG造影1例。结果ICG造影显示动脉瘤均完全夹闭，载瘤动脉通畅。3例病人术后复查DSA，均证实术中ICG造影结果。结论ICG血管造影能在术中即时发现动脉瘤是否残留，载瘤动脉是否狭窄，从而指导手术医师术中进行调整。     

Acute increases in forebrain blood flow during alerting responses in conscious rabbits

We have previously shown that alerting responses (documented by appearance of theta rhythm in the hippocampal EEG) are associated with a characteristically timed acute vasoconstriction in the ear artery bed of the conscious rabbit. We have now determined what happens to forebrain blood flow (Doppler probe chronically implanted around the internal carotid artery) during similar alerting responses in conscious rabbits, comparing forebrain flow to simultaneously measured ear flow. During an alerting response, forebrain flow increased by 31±8% of baseline (n=6, P<0.01), with the increase commencing within 1 s of the stimulus, at approximately the same time as the decrease in ear flow. Arterial pressure increased from 77±3 to 81±3 mmHg (P<0.01), so that internal carotid conductance increased from 0.17±0.02 to 0.20±0.02 kHz/mmHg (P<0.01). During a 1 h continuous recording period in the laboratory there was a negative correlation between forebrain and skin flow, with the Pearson coefficient in individual rabbits ranging from −0.18 to −0.62 (n=6, all correlations P<0.01). During this period, forebrain blood flow was just as variable, from second to second, as distal aortic flow, but not as variable as ear blood flow. Our study thus demonstrates that alerting responses in rabbits are associated with rapid increases in cerebral vascular conductance. We believe that this is the first demonstration of this phenomenon in the conscious experimental animal.     

Functional assessment of the sympathetic innervation of the microcirculation of the lower urinary tract: A preliminary report

This paper presents preliminary data on a new method for testing the sympathetic innervation of the urothelium. A flexible laser Doppler probe was introduced into the urethra of two females and two male subjects. The percentage fall in laser Doppler flux following generalized sympathetic stimulation by taking an inspiratory gasp was measured. This resulted in 36%, 32%, 68% and 34% mean drop in urothelial blood flux. In the female subjects, the probe was advanced into the bladder and the procedure repeated, and the gasp resulted in 60% and 83% drop in flux. With laser Doppler fluxmetry, fall in microcirculatory blood flow associated with a generalized increase in sympathetic tone, therefore can be demonstrated. This method may be useful in the assessment of the integrity of the sympathetic innervation of the urothelium in patients with suspected autonomic dysfunction of the genitourinary tract.