The accuracy of transcranial Doppler to detect vasospasm in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVES. To examine the accuracy of transcranial Doppler to detect cerebral vasospasm in a patient population with aneurysmal subarachnoid hemorrhage. DESIGN. Prospective blind comparison of transcranial Doppler with cerebral angiography. Diagnostic accuracy of transcranial Doppler was assessed using receiver operating characteristic (ROC) analysis and likelihood ratios. Sensitivity and specificity were calculated using directly measured middle cerebral artery diameter as reference standard. SETTING. Intensive Care Unit of a large university teaching hospital. PATIENTS AND PARTICIPANTS. Twenty-two patients with subarachnoid hemorrhage were included. Patients underwent angiography on admission and after 8 days to diagnose vasospasm and were defined as having clinical vasospasm, angiographic vasospasm, or no vasospasm. MEASUREMENTS AND RESULTS. Sensitivity and specificity were 1.00 and 0.75 for angiographic vasospasm and both equal to 1.00 for clinical vasospasm diagnosis. A transcranial Doppler mean velocity threshold value of 100 cm/s for angiographic vasospasm and 160 cm/s for clinical vasospasm detection were chosen by ROC analysis. CONCLUSIONS. A Transcranial Doppler mean velocity threshold of 160 cm/s, calculated by the ROC analysis, accurately detects clinical vasospasm. A daily transcranial Doppler examination performed by a trained operator should be routinely used to provide early identification of patients at high risk and to orient therapeutic decisions.     

Xenon-CT and transcranial Doppler in poor-grade or complicated aneurysmatic subarachnoid hemorrhage patients undergoing aggressive management of intracranial hypertension

Objective To evaluate whether elevated flow velocimetry values are associated with critically reduced cerebral blood flow values in deeply sedated patients with acute aneurysmatic subarachnoid hemorrhage and in whom the detection of clinical vasospasm is not feasible. Design Retrospective analysis of prospectively collected data.Setting Neurosurgical and trauma patients in an intensive care unit in a regional hospital.Patients and participants Twenty-nine patients in the acute phase following subarachnoid hemorrhage who were sedated and ventilated for elevated intracranial pressure, transcranial Doppler vasospasm, or respiratory failure and were studied with at least a coupled xenon-CT/transcranial Doppler study.Measurements and results Combined measurement and comparison of cerebral blood flow by means of xenon-CT and of mean velocity by means of transcranial Doppler in middle cerebral artery territories. The case mix studied was consistent with patients' predominantly poor grade and with a complicated course. The results suggest that in sedated patients flow velocity and measured cortical mixed cerebral blood flow are not correlated, and, more specifically, that flow velocities values above 120 or 160 cm/s and Lindegaard index above 3 are not associated with an ischemic regional cerebral blood flow. Conversely, as many as 55% of the xenon-CT studies were associated with hyperemia.Conclusions In patients with elevated intracranial pressure, mean middle cerebral artery flow velocity or Lindegaard Index does not help to detect critical cerebral blood flow nor elevated cerebral blood flow.     

Accuracy of transcranial Doppler sonography for predicting cerebral infarction in aneurysmal subarachnoid hemorrhage

PURPOSE: To evaluate the accuracy of transcranial Doppler (TCD) sonography using different criteria for predicting cerebral infarction due to symptomatic vasospasm. METHODS: We retrospectively evaluated the clinical and radiologic data of consecutive patients admitted with acute aneurysmal subarachnoid hemorrhage (SAH) in the anterior cerebral circulation between January 2001 and June 2002. TCD sonographic examinations were performed on alternate days up to 20 days after admission. Cerebral infarction was defined on CT as a new hypodensity in the vascular distribution with corresponding clinical symptoms. Vasospasm was diagnosed as mild or severe when TCD sonography revealed a mean blood flow velocity (MBFV) greater than 120 and 180 cm/s in the middle or anterior cerebral artery and in the intracranial part of the internal carotid artery, respectively. RESULTS: A total of 93 patients with aneurysmal SAH in the anterior cerebral circulation were included. Vasospasm was demonstrated by TCD sonography in 60 patients (64.5%) and was shown via multivariable logistic regression analysis to be predictive of cerebral infarction (OR 3.11, 95% CI 1.46-6.59), with an 82.6% and 69.6% sensitivity, a 41.4% and 77.1% specificity, a 31.7% and 50.0% positive predictive value, and an 87.9% and 88.5% negative predictive value when the MBFV was greater than 120 and 180 cm/s, respectively. CONCLUSIONS: Vasospasm on TCD was found to be predictive of symptomatic cerebral infarction on CT, but its positive predictive value remained low despite the adoption of restrictive TCD criteria for vasospasm.     

Continuous measurement of cerebral blood flow velocity using transcranial Doppler reveals significant moment-to-moment variability of data in healthy volunteers and in patients with subarachnoid hemorrhage

OBJECTIVE: The reliability of intermittent transcranial Doppler has not been accepted widely because of problems with interobserver variability and lack of accuracy. The limitations of intermittent transcranial Doppler are thought to be overcome by continuous measurement systems. However, little published data exist on their accuracy, feasibility, and moment-to-moment variability. In this study we aimed to determine the time-related variability of continuous transcranial Doppler signal from volunteers and patients with subarachnoid hemorrhage and to examine the feasibility, ease of use, and quality of data generated from continuous transcranial Doppler for the detection of vasospasm. DESIGN: Prospective observational study. SETTING: Intensive care unit in a tertiary referral center. SUBJECTS: Ten volunteers and eight patients with aneurysmal subarachnoid hemorrhage. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The middle cerebral artery blood flow velocities were recorded continuously from both patients and volunteers. The moment-to-moment variability of continuously recorded data was calculated. There was a wide range of velocity measurements in both volunteers and patients. There was a significant moment-to-moment variability in both volunteers (-31% to 58%) and in patients (-38% to 78%). There was a greater number of observations exceeding 10% moment-to-moment variability in the patient group with regard to systolic and diastolic velocities compared with volunteers (8% vs. 2%, p < .001). There was a trend toward a longer duration of good quality data in volunteers compared with patients (98 +/- 0.5% vs. 96 +/- 9%). CONCLUSIONS: Continuous measurement of cerebral blood flow velocities revealed a significant moment-to-moment variability in both patients and in volunteers, the magnitude of which was greater in the patients. The clinical implications of these findings are discussed.     

Age dependence of the flow velocity in the basal cerebral arteries--a transcranial Doppler ultrasound study

The age dependence of the blood flow velocities of the middle, anterior, and posterior cerebral arteries measured by the transcranial Doppler method is discussed and compared with the velocity values in the internal carotid artery. A number of 535 patients without neurological deficits but with a previous neurological event were examined. Flow velocities decrease in all examined vessels with increasing age. This is in accordance with cerebral blood flow measurements by Xenon inhalation techniques. The reasons of the decrease and its consequences on the vasospasm in patients suffering from subarachnoidal hemorrhage are discussed.     

Transcranial Doppler in stroke.

Transcranial Doppler (TCD) has been extensively used in various clinical situations, and in the last two decades has established its role in the management of patients with cerebrovascular disease and stroke. Based on the Doppler principle, it uses ultrasound waves to insonate the blood vessels supplying the brain to obtain hemodynamic information. Anatomic abnormalities of vascular occlusion, stenosis and spasm can be indirectly derived. Intracranial arterial disease is an important cause of ischemic stroke and TCD can detect these with a fair amount of sensitivity and specificity. In hemodynamically significant extracranial internal carotid artery disease, TCD shows significant abnormalities in flow dynamics of the anterior circulation and abnormalities of cerebral vasomotor reactivity. A distinct advantage of TCD is the ability to monitor blood flow in a blood vessel over prolonged periods of time, which has shown microembolic signals in acute ischemic stroke, carotid artery disease, atrial fibrillation and during angiography. In acute ischemic stroke, TCD can be used to elucidate stroke mechanisms, plan and monitor treatment, and determine prognosis. In an era when stroke is increasingly being recognized as an emergency requiring immediate treatment, TCD may be capable of providing rapid information about the hemodynamic status of the cerebral circulation, within the time frame of the rather small 'therapeutic window'. TCD predicts vasospasm with a high degree of sensitivity and specificity and because of its non-invasive nature repeated assessments can be performed after subarachnoid hemorrhage.     

法舒地尔防治动脉瘤介入栓塞术后脑血管痉挛的疗效观察

【目的】探讨盐酸法舒地尔防治颅内动脉瘤破裂蛛网膜下腔出血（SAH）介入栓塞术后脑血管痉挛（CVS）的效果。【方法】将60例脑动脉瘤破裂SAH介入栓塞术后患者随机分为治疗组和对照组各30例,治疗组术后给予法舒地尔30mg静脉滴注q8h,疗程14d,每次静脉滴注时间为30min;对照组30例,术后采用尼莫地平,1mg／h,静脉泵入,疗程14d,比较两组的Glasgow评分,头部CT及经颅多普勒（TCD）观察大脑中动脉（MCA）血流速度的变化。【结果】法舒地尔与尼莫地平均可迅速促进疾病的好转;对CT检查所见脑内低密度灶,法舒地尔与尼莫地平均可使其改善;法舒地尔与尼莫地平扩张痉挛脑动脉的作用较好,两者无显著性差异（P〉0．05）。【结论】法舒地尔与尼莫地平均是预防和治疗动脉瘤破裂SAH介入栓塞术后CVS安全有效的药物。     

Intravenous magnesium sulfate administration in a patient with refractory vasospasm following subarachnoid hemorrhage

OBJECTIVE: Magnesium sulfate is being investigated for the prevention or treatment of vasospasm following subarachnoid hemorrhage. PATIENT: A 45-year-old woman suffered subarachnoid hemorrhage and developed after 8 days symptomatic vasospasm in the left middle cerebral artery (MCA) while she was receiving nimodipine prophylactically. METHODS AND RESULTS: Transcranial Doppler monitoring was performed. Cerebral autoregulation was abolished in the left MCA. Despite this finding the administration of a bolus dose of MgSO(4), followed by a continuous infusion in order to achieve serum magnesium levels in the range of 4-4.5 mg/dl (1.65-1.85 mmol/l), resulted in a marked decrease (12.2%) of the left MCA mean blood flow velocity, without clinically relevant change in systemic blood pressure (3%). This effect was maintained for at least 4 h. It did not prevent the development of ischemic lesions.     

Hyperemia following aneurysmal subarachnoid hemorrhage: incidence,diagnosis, clinical features,and outcome

OBJECTIVE: Hyperemia is a known phenomenon after aneurysmal subarachnoid hemorrhage, but only a few reports describe and analyze hyperemia in these patients. This could be the result of diagnostic difficulties in order to identify elevated cerebral blood flow; thus, it seems that hyperemia could be an underdiagnosed clinical state. The aim of the study was to evaluate this phenomenon in comparison with clinical outcome and imaging data in order to describe the frequency of hyperemia after subarachnoid hemorrhage and maybe improve clinical diagnosis. DESIGN: Retrospective analysis of our cerebral blood flow and transcranial Doppler sonography data bank. SETTING:. Neurosurgical/Anesthesiological intensive care unit University of Regensburg, Regensburg, Germany. PATIENTS AND PARTICIPANTS: A total of 37 patients were included (24 women and 13 men). All patients suffered from aneurysmal subarachnoid hemorrhage. MEASUREMENTS AND RESULTS: Standard transcranial Doppler ultrasonography, as well as the Xenon(133) clearance technique for cerebral blood flow measurements, was employed. We observed 37 increases of flow velocities in 37 patients according to Doppler ultrasonography. In order to distinguish between ischemia and hyperemia a Xenon(133) regional cerebral blood flow examination was performed. Global hyperemia was detected in 5 patients (14%). Hyperemia correlated only to favorable outcome ( p=0.01) and fewer ischemic lesions in the computed tomography ( p<0.05). CONCLUSION: The results indicate that while global hyperemia is a frequent phenomenon that cannot be detected by standard Doppler ultrasonography or clinical examination, hyperemic cerebral blood flow values following aneurysmatic subarachnoid hemorrhage are correlated to favorable outcome.     

Possible overlap between reversible cerebral vasoconstriction syndrome and symptomatic vasospasm after aneurysmal subarachnoid hemorrhage

A 34-year-old woman with a previous history of severe headache (“thunderclap”) was admitted with a diagnosis of aneurysmal subarachnoid hemorrhage (SAH). The patient developed symptomatic vasospasm on day 5 that resolved rapidly after having increased arterial blood pressure. She experienced also short-lasting excruciating headache. On day 12, while velocities had normalised, as revealed by transcranial Doppler (TCD), for more than 48 h, she developed aphasia and right hemiplegia associated with diffuse segmental vasospasm on the left middle cerebral artery. Intra-arterial infusion of vasodilatory agents was required. Recurrence of symptomatic vasospasm was noted on day 25, with a great number of territories involved as shown in the cerebral angiogram. A second intra-arterial treatment was needed. The patient complained of multiple episodes of extremely severe headache (“thunderclap”), with also transient dysarthria and hemiparesia on day 30. She was discharged on day 38 after full recovery. The clinical and TCD/radiological findings were consistent with a reversible cerebral vasoconstriction syndrome overlapping SAH related symptomatic vasospasm.     

Role of transcranial Doppler in optimizing treatment of cerebral vasospasm in subarachnoid hemorrhage

This study was undertaken to evaluate the role of transcranial Doppler ultrasonography in arterial blood pressure management during hypervolemia/hypertension/ hemodilution therapy in patients with vasospasm from subarachnoid hemorrhage and correlate this data with neurologic outcome. The study included 18 adult patients, Hunt and Hess grades III-IV. Complete neurologic assessment was performed. Transcranial Doppler indices were calculated by standard formulas. On the basis of our results, resistance area product can be used to estimate the optimal arterial blood pressure in hypervolemia/hypertension/hemodilution therapy. An increase in the cerebral blood flow index was associated with better performance on neurologic examination. Estimated cerebral perfusion pressure from transcranial Doppler data analysis showed poor correlation with cerebral perfusion pressure derived from direct measurement of intracranial pressure in patients with cerebral vasospasm (rho = 0.15; 95% CI, 0.11-0.39; P = .2590).     

经颅多普勒超声在外伤性颈内动脉海绵窦瘘诊断中的价值

目的 探讨经颅多普勒超声(TCD)检测脑血流对外伤性颈内动脉海绵窦瘘的诊断、治疗和术中监测的价值。方法 使用TCD检测25例有颅内杂音、突眼及其他存在海绵窦瘘的高危原因的颅脑外伤患者，所有病例均经数字减影血管造影(DSA)明确诊断。栓塞术中TCD监测评价脑血流状态的变化和栓塞的效果，并与DSA检查结果对照。用DSA检查未见脑血管异常的18例患者的TCD资料为对照。结果 TCD检测发现颈内动脉颅外段的高流速低阻力频谱，大脑中、前动脉的低流速低阻力频谱以及眼上静脉异常频谱为颈内动脉海绵窦瘘的特征性改变，具有较高的准确性和特异性。术中TCD监测可实时准确地评估栓塞是否成功。结论 TCD检测是诊断颈内动脉海绵窦瘘、指导治疗、术中监测、疗效评估和随访的有效手段，具有无创、准确和可重复的优点。     

Inhalation versus endovenous sedation in subarachnoid hemorrhage patients: Effects on regional cerebral blood flow*

OBJECTIVE:: Isoflurane is a volatile anesthetic that has a vasodilating effect on cerebral vessels producing a cerebral blood flow increase. Furthermore, it has been shown in animal studies that isoflurane, when used as a preconditioning agent, has neuroprotective properties, inducing tolerance to ischemia. However, it is not routinely used in neurointensive care because of the potential increase in intracranial pressure caused by the rise in cerebral blood flow. Nevertheless, subarachnoid hemorrhage patients who are at risk for vasospasm may benefit from an increase in cerebral blood flow. We measured regional cerebral blood flow during intravenous sedation with propofol and during sedation with isoflurane in patients with severe subarachnoid hemorrhage not having intracranial hypertension. DESIGN:: The study is a crossover, open clinical trial (NCT00830843). SETTING:: Neurointensive care unit of an academic hospital. PATIENTS:: Thirteen patients with severe subarachnoid hemorrhage, (median Fisher scale 4), monitored on clinical indication with intracranial pressure device and a thermal diffusion probe for the assessment of regional cerebral blood flow. An intracranial pressure >18 mm Hg was an exclusion criterion. INTERVENTIONS:: Cerebral and hemodynamic variables were assessed at three steps. Step 1: sedation with propofol 3-4 mg/kg/hr; step 2: after 1hr of propofol discontinuation and isoflurane 0.8%; step 3: after 1hr of propofol at the same previous infusion rate. Cerebral perfusion pressure and arterial PCO2 were maintained constant. Mean cerebral artery flow velocity and jugular vein oxygen saturation were measured at the end of each step. MEASUREMENTS AND MAIN RESULTS:: Regional cerebral blood flow increased significantly during step 2 (39.3±29mL/100 hg/min) compared to step 1 (20.8±10.7) and step 3 (24.7±8). There was no difference in regional cerebral blood flow comparing step 1 vs. step 3. No significant difference in intracranial pressure, mean cerebral artery transcranial Doppler velocity, PaCO2, cerebral perfusion pressure between the different steps. CONCLUSIONS:: Isoflurane increases regional cerebral blood flow in comparison to propofol. Intracranial pressure did not change significantly in the population not affected by intracranial hypertension.     

经颅彩色多普勒超声评价外伤性蛛网膜下腔出血患者大脑中动脉血管痉挛

目的探讨经颅彩色多普勒超声(TCCS)在评价外伤性蛛网膜下腔出血患者大脑中动脉痉挛程度中的作用。方法对经CT确诊的外伤性蛛网膜下腔出血患者100例,采用TCCS观察大脑中动脉彩色血流束的走行、方向、有无局部充盈缺损和色彩混叠,频谱多普勒检测大脑中动脉收缩期峰值血流速度(VMCA)及同侧颈内动脉入颅段的血流速度(VICA),计算Lindegaard指数=VMCA/VICA。检查时间分别在脑外伤后1~3d、10d、14d,每次均测量3次取平均值。根据有无脑血管痉挛症状,分为有症状和无症状组,并对两组血流参数进行比较分析。结果外伤后3~7d蛛网膜下腔出血患者开始出现不同程度的脑血管痉挛症状,以6~10d最显著,2周以后逐渐减轻,其中外伤后10d35例符合大脑中动脉痉挛的诊断标准;有症状组VMCA和Lindgaard指数明显大于无症状组(P<0.01或P<0.05)。结论TCCS检测外伤性蛛网膜下腔出血患者的大脑中动脉VMCA和Lindgaard指数可以很好地了解大脑中动脉痉挛程度。     

Cerebral autoregulation testing after aneurysmal subarachnoid hemorrhage: the phase relationship between arterial blood pressure and cerebral blood flow velocity

OBJECTIVE: Impairment of cerebral autoregulation (CA) appears to be an important cause for secondary ischemia after subarachnoid hemorrhage (SAH). It has been shown that graded CA impairment is predictive of outcome. Little is known about whether such impairment is present, what causes CA impairment, whether it precedes vasospasm, and whether it is predictive of outcome in patients with severe aneurysmal SAH. DESIGN: Prospective, controlled study. SETTING: Neurosurgical intensive care unit. PATIENTS: Twelve patients after aneurysmal subarachnoid hemorrhage, 40 controls. INTERVENTIONS: Recording of cerebral blood flow velocities and continuous measurement of arterial blood pressure at a controlled ventilatory frequency of six per minute to standardize the influence of intrathoracic pressure changes on blood pressure. MEASUREMENTS AND MAIN RESULTS: We calculated the phase shift angles (deltaphidegrees) between slow (0.1 Hz) arterial blood pressure and cerebral blood flow velocity waves measured by transcranial Doppler ultrasound in the middle cerebral artery during a) posthemorrhage days (PHD) 1-6 (early or prevasospasm phase), and b) during PHD 7-13 (late or vasospasm phase) using a 6/min ventilation protocol, and in 40 controls spontaneously ventilating at the same rate. deltaphi <30 degrees indicated lost CA. Mean flow velocities >100 cm/sec were considered vasospasm. We combined early and late measurements to assess the CA relationship with low cerebral perfusion pressure (CPP) and/or vasospasm. We assessed the Glasgow Outcome Scale (GOS) score at discharge (1 = worst, 5 = best). The admission Hunt and Hess score was 3.6 +/- 0.7. GOS scores were n = 3 (GOS 1), n = 2 (GOS 2), n = 5 (GOS 3), n = 1 (GOS 4), and n = 1 (GOS 5). In the early phase, deltaphi was 40.4 +/- 19.8 degrees (left), and 40.4 +/- 19.2 degrees (right). CPP was 69.4 +/- 10.9, intracranial pressure (ICP) was 6.7 +/- 2.8 mm Hg. In the late phase, deltaphi worsened in six patients and none improved: 32.1 +/- 21 degrees (left), and 26.9 +/- 17.2 degrees (right); CPP was 68.1 +/- 12.1, ICP was 7.5 +/- 3.7 mm Hg. CA was significantly impaired in both phases when compared with normal subjects (deltaphi: 65.7 +/- 24.5 degrees; p < .01 for early, p < .001 for late phase). In the early phase, seven of eight patients in whom autoregulation was intact had a GOS >2 at discharge and disturbed CA on at least one side was predictive of either vegetative condition at discharge or death (p < .01). In the late phase, deltaphi was no longer predictive of outcome. Spasm was present in 8 of 17 vessels (47%) in which CA was lost; no spasm was found in 25 of 28 vessels (89%) in which CA was intact (p < .01). A low CPP was present in 6 of 17 vessels (35%) in which CA was lost; a normal CPP was found in 21 of 27 vessels (78%) in which CA was intact (p > .05, NS). However, 14 of 17 vessels (82%) with lost CA showed spasm and/or low CPP while only 8 of 27 cases (30%) with intact CA had either spasm or low CPP (p < .001). CONCLUSIONS: CA can be assessed in a graded fashion in SAH patients. CA impairment precedes vasospasm; ongoing vasospasm worsens CA. CA assessment early after subarachnoid hemorrhage, within PHD 1-6, is predictive of outcome whereas late assessment is not. CA impairment is associated with cerebral vasospasm and low CPP.     

Early identification of patients at risk for symptomatic vasospasm after aneurysmal subarachnoid hemorrhage

OBJECTIVE: To develop a scheme for early identification of individuals at risk for symptomatic vasospasm after subarachnoid hemorrhage (SAH). DESIGN: Analysis of prospectively collected data from the placebo-treated group in a multicenter clinical trial. SETTINGS: Fifty-four neurosurgical centers in North America. MEASUREMENTS AND MAIN RESULTS: We identified independent predictors of symptomatic vasospasm using stepwise logistic regression analysis from demographic, clinical, laboratory, and neuroimaging characteristics of the participants. We developed a scoring system (symptomatic vasospasm risk index) based on a combination of these predictors. Out of 283 patients in the analysis (all treated with oral nimodipine), 93 (33%) developed symptomatic vasospasm within 14 days after SAH. There were four independent predictors of symptomatic vasospasm: thickness of subarachnoid clot on computed tomographic scan (odds ratio [OR], 4.1; 95% confidence interval [CI], 1.8-10.0); early rise in middle cerebral artery mean flow velocity (MCA-MFV), defined as a value > or =110 cm/sec recorded on or before post-SAH day 5 (OR, 1.9; 95% CI, 1.1-3.3), Glasgow Coma Scale score <14 (OR, 1.8; 95% CI, 1.1-3.1); and rupture of anterior cerebral or internal carotid artery aneurysm (OR, 1.9; 95% CI, 1.0-3.4). The probability of identifying patients who would develop symptomatic vasospasm (percentage of area under receiver operating characteristics curve +/- SEM) was higher with symptomatic vasospasm risk index (68%+/-8%) compared with thickness of clot (62%+/-8%; p = .08) or MCA-MFV (45%+/-7%, p < .05) criteria alone. CONCLUSIONS: Patients at high risk for symptomatic vasospasm can be identified early in the course of SAH using a risk index. A risk index based on a combination of variables may represent a predictive paradigm superior to conventionally used criteria based on clot thickness or MCA-MFV criteria.     

Cerebrovascular dynamics with head-of-bed elevation in patients with mild or moderate vasospasm after aneurysmal subarachnoid hemorrhage.

BACKGROUND: In patients with aneurysmal subarachnoid hemorrhage, elevation of the head of the bed during vasospasm has been limited in an attempt to minimize vasospasm or its sequelae or both. Consequently, some patients have remained on bed rest for weeks. OBJECTIVES: To determine how elevations of the head of the bed of 20 degrees and 45 degrees affect cerebrovascular dynamics in adult patients with mild or moderate vasospasm after aneurysmal subarachnoid hemorrhage and to describe the response of mild or moderate vasospasm to head-of-bed elevations of 20 degrees and 45 degrees with respect to variables such as grade of subarachnoid hemorrhage and degree of vasospasm. METHODS: A within-patient repeated-measures design was used. The head of the bed was positioned in the sequence of 0 degrees -20 degrees -45 degrees -0 degrees in 20 patients with mild or moderate vasospasm between days 3 and 14 after aneurysmal subarachnoid hemorrhage. Continuous transcranial Doppler recordings were obtained for 2 to 5 minutes after allowing approximately 2 minutes for stabilization in each position. RESULTS: No patterns or trends indicated that having the head of the bed elevated increases vasospasm. As a group, there were no significant differences within patients at the different positions of the head of the bed. Utilizing repeated-measures analysis of variance, P values ranged from .34 to .97, well beyond .05. No neurological deterioration occurred. CONCLUSIONS: In general, elevation of the head of the bed did not cause harmful changes in cerebral blood flow related to vasospasm.     

自发性蛛网膜下腔出血后低钠血症的临床研究

目的 研究自发性蛛网膜下腔出血(SAH)患者低钠血症的发生情况.方法 对36例蛛网膜下腔出血患者按出血量、病情轻重、脑血管痉挛的情况及血钠水平进行动态观察.用TCD检测大脑中动脉血流速度(VMCA).结果 脑血管痉挛的患者其血钠水平明显降低,有明显的临床意义.结论 低钠血症是蛛网膜下腔出血常见的并发症,且是反映蛛网膜下腔出血病情程度的一个重要指标.应严密监测并及时明确病因、尽早治疗,以改善病情及预后.     

Cerebral blood flow and CO2 reactivity in interictal migraineurs: a transcranial Doppler study

There is still some controversy about alterations in velocity of blood flow and in cerebral vasomotor reactivity of intracranial arteries in migraineurs during the interictal phase. By means of simultaneous bilateral transcranial Doppler ultrasonography we, therefore, assessed intracranial blood flow velocities and cerebrovascular reactivity to carbon dioxide of all three basal brain arteries in 20 migraineurs during the interictal phase and 30 nonheadache-prone control subjects. Mean blood flow velocities were higher in migraineurs than in controls in all three arteries on both sides, with a significant difference (P < 0.05) for the right anterior cerebral artery and middle cerebral artery under basal conditions and for the right posterior cerebral artery during hypercapnia. Similarly, the cerebrovascular reactivity to carbon dioxide was always higher in patients than in controls, with a significant difference for the left anterior and the right middle cerebral arteries (P < 0.05) and the right posterior cerebral artery (P < 0.01). The broad overlap of cerebrovascular blood flow velocities and CO2 reactivities in patients and controls precluded identification of values diagnostic of migraine. Nevertheless, transcranial Doppler ultrasonography offers the opportunity to noninvasively monitor cerebral blood flow parameters and, therefore, represents a valuable tool for vascular research in migraine.     

Using transcranial Doppler sonography to augment the neurological examination after aneurysmal subarachnoid hemorrhage.

Vasospasm is the leading cause of death in patients who survive initial subarachnoid hemorrhage (SAH). Evidence of blood in the subarachnoid space on computed tomography (CT) scan can often predict the occurrence of vasospasm. Clinically, the onset of new or worsening neurological symptoms is the most reliable indicator of vasospasm. Transcranial Doppler (TCD) sonography studies can further aid the neuroscience nurse's assessment for vasospasm by measuring cerebral blood flow velocities. Physiological changes that occur during vasospasm cause the lumen of the blood vessel to decrease, increasing blood flow velocity through the affected area. Although vasospasm can only be definitively diagnosed by cerebral angiogram, TCD sonography provides a noninvasive, low-risk assessment tool that can be done at the beside. By coupling a patient's vital neurological data with blood flow velocity trends, the neuroscience nurse can anticipate the onset or worsening of vasospasm. This advanced nursing assessment allows for collaboration with the medical team to initiate and adjust appropriate therapies to improve patient outcomes.