The relation between cerebral blood flow velocities as measured by TCD and the incidence of delayed ischemic deficits. A prospective study after subarachnoid hemorrhage

Magnesium sulfate in combination with nimodipine for the treatment of subarachnoid hemorrhage: a randomized controlled clinical study

Objective Cerebral vasospasm(CVS) after Subarachnoid hemorrhage (SAH) can cause delayed cerebral ischemia,secondary cerebral infarction, and rehemorrhage, which are the leading causes of mutilation and death. Nimodipine has been shown to prevent CVS. Magnesium ion (Mg²⁺) can competitively inhibit the influx of calcium (Ca²⁺) and prevent vasospasm. There is evidence that magnesium sulfate can prevent CVS and reduce infarct volume after SAH. In this study, we evaluated the efficacy and safety of intravenous magnesium sulfate combined with oral nimodipine on CVS, delayed cerebral ischemia, secondary cerebral infarction, and rehemorrhage after SAH. Methods This is a prospective randomized, double-blind trial of 120 patients with SAH who were recruited between January 2003 and January 2009. These patients were assigned to two groups and received the same basic treatment and symptomatic treatment. In group A, patients received 14 days of intravenous administration of 1400 mL 0.9% normal saline + 40 mL 25% magnesium sulfate, 1 mL/min, once per day, followed 7 days of intravenous administration of 500 mL 0.9% normal saline + 15 mL 25% magnesium sulfate, 1 mL/min, once per day and oral nimodipine, 20 mg once, four times a day, for 21 days. Patients in group B received identical treatment to that in group A, except that 25% magnesium sulfate was replaced by placebo. On day 22 of treatment, incidences of intracranial CVS, delayed cerebral ischemia, secondary cerebral infarction, rehemorrhage, neurologic deficits, and death were assessed and adverse events were monitored. Results CVS occurred in 4, 12 patients, lasting for 11.09 ± 5.38, 13.73 ± 6.24 hours, mean velocity (Vm) of 143.2 ± 12.7, 149.6 ± 18.9 cm/s in group A, B; Delayed cerebral ischemia occurred in 3, 10 patients, lasting for 13.16 ± 4.82, 15.57 ± 5.35 hours in group A, B; Secondary cerebral infarction occurred in 2 and 8 patients in groups A and B; Neurologic deficits occurred in3 and 11 patients in groups A and B, All P < 0.05; Rehemorrhage occurred in 4 and 5 patients; Death occurred in 5 and 8 patients in groups A and B, respectively, P >0.05. No obvious adverse events were found in both groups. Conclusion Intravenous magnesium sulfate in combination with oral nimodipine for the treatment of SAH can help reduce the incidences of CVS, delayed cerebral ischemia, secondary cerebral infarction, and neurologic deficits with good safety, but it does not reduce the incidences of rehemorrhage and death.

Identification of specific age groups with a high risk for developing cerebral vasospasm after aneurysmal subarachnoid hemorrhage

The impact of age on the incidence of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH) is a matter of ongoing discussion. The aim of this study was to identify age groups with a higher risk for developing vasospasm, delayed ischemic neurological deficit (DIND), or delayed infarction (DI) and to identify a cut-off age for a better risk stratification. We defined six age groups (<30, 30-39, 40-49, 50-59, 60-69, and >70 years). ROC analysis was performed to determine a cutoff age with the highest positive predictive value (PPV) for developing vasospasm, defined as a blood-flow-velocity-increase >120 cm/s in transcranial-Doppler-sonography (TCD). Multivariate binary-logistic-regression-analysis was then performed to evaluate differences in the incidence of cerebral vasospasm, DIND, and DI among the different age groups. A total of 753 patients were included in the study. The highest incidence (70 %) of TCD-vasospasm was found in patients between 30 and 39 years of age. The cutoff age with the highest PPV (65 %) for developing TCD-vasospasm was 38 years. Multivariate analysis revealed that age <38 years (OR 3.6; CI 95 % 2.1-6.1; p < 0.001) best predicted vasospasm, followed by the need for cerebrospinal fluid drainage (OR 1.5; CI 95 % 1.0-2.3; p = 0.04). However, lower age did not correlate with higher rates of DIND or infarcts. The overall vasospasm-incidence after aSAH is age-dependent and highest in the age group <38 years. Surprisingly, the higher incidence in the younger age group does not translate into a higher rate of DIND/DI. This finding may hint towards age-related biological factors influencing the association between arterial narrowing and cerebral ischemia.

Therapeutic hypothermia reduces middle cerebral artery flow velocity in patients with severe aneurysmal subarachnoid hemorrhage

BACKGROUND

Transcranial Doppler (TCD) is widely used to detect and follow up cerebral vasospasm after subarachnoid hemorrhage (SAH). Therapeutic hypothermia might influence blood flow velocities assessed by TCD. The aim of the study was to evaluate the effect of hypothermia on Doppler blood flow velocity after SAH.

METHODS

In 20 patients treated with hypothermia (33°) due to refractory intracranial hypertension or delayed cerebral ischemia (DCI), mean flow velocity of the middle cerebral artery (MFV(MCA)) was assessed by TCD. Thirteen patients were treated with combined hypothermia and barbiturate coma and seven with hypothermia alone. MFV(MCA) was obtained within 24 h before and after induction of hypothermia as well as before and after rewarming.

RESULTS

Hypothermia was induced on average 5 days after SAH (range 1-12) and maintained for 144 h (range 29-270). After hypothermia induction, MFV(MCA) decreased from 113.7 ± 49.0 to 93.8 ± 44.7 cm/s (p = 0.001). The decrease was independent of SAH-related complications and barbiturate coma. MFV(MCA) further decreased by 28.2 cm/s between early and late hypothermia (p < 0.001). This second decrease was observed in patients with DCI (p < 0.001), but not in patients with intracranial hypertension (p = 0.715). Compared to late hypothermia, MFV(MCA) remained unchanged after rewarming (65.6 ± 32.1 vs 70.3 ± 36.8 cm/s; p = 0.219). However, patients treated with hypothermia alone showed an increase in MFV(MCA) after rewarming (p = 0.016).

CONCLUSION

Therapeutic hypothermia after SAH decreases Doppler blood flow velocity in both intracranial hypertension and DCI cases. The results can be the effect of hypothermia-related mechanisms or resolving cerebral vasospasm during prolonged hypothermia.

Time course of cerebral hemodynamics in aneurysmal subarachnoid hemorrhage

BACKGROUND

Vascular complications are important causes of neurologic sequelae among survivors of aneurysmal subarachnoid hemorrhage (SAH). However, little is known about the time course of cerebral hemodynamics and outcome in patients with and without angiographically confirmed cerebral vasospasm.

METHODS

Serial transcranial color-coded sonography (TCCS), angiography, and MRI studies were performed to measure cerebrovascular hemodynamics and assess complications following aneurysmal SAH.

RESULTS

Eighteen aneurysmal SAH patients were enrolled. Angiographically confirmed cerebral vasospasm occurred in 14 patients (77.8%), 5 of whom (35.7%) were asymptomatic. The mean blood flow velocity (V(mean) ) of the middle cerebral artery increased significantly as compared with healthy volunteers from day 1 to day 15, and substantially decreased thereafter. The V(mean) of middle cerebral artery was significantly higher in patients with than in patients without angiographically confirmed cerebral vasospasm from day 3 to day 12. Compared to angiography, TCCS detected cerebral vasospasm with 85.7% sensitivity, 100% specificity, 100% positive predictive value, and 66.7% negative predictive value. MRI-evidenced cerebral infarctions occurred in nine patients (50%), three of whom (33.3%) were asymptomatic.

CONCLUSIONS

This study demonstrated that approximately one-third of acute phase aneurysmal SAH patients have asymptomatic delayed cerebral infarction, which was undetected by TCCS in one-third of them. This may explain why the accuracy of TCCS to predict clinical symptomatic cerebral vasospasm is suboptimal.

Prediction of symptomatic cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage: relationship to cerebral salt wasting syndrome

OBJECTIVES

Symptomatic cerebral vasospasm is a major complication in patients with subarachnoid hemorrhage (SAH). Symptomatic cerebral vasospasm has been reported to be related to the patient's blood volume which is influenced by cerebral salt wasting syndrome (CSWS). We undertook a prospective study to assess whether the onset of symptomatic cerebral vasospasm was predictable or not, by observing the phenomena of CSWS (natriuresis and osmotic diuresis).

METHODS

Sixty-seven consecutive aneurysmal SAH patients were analysed. After surgery, all patients underwent hypervolemic therapy in order to keep central venous pressure (CVP) within 8-12 cmH(2)O, serum sodium level above 140 mEq/l and a positive water balance. Patients were classified into two groups: those without symptomatic cerebral vasospasm (n=55) and those with symptomatic cerebral vasospasm (n=12). To estimate natriuresis and osmotic diuresis, sodium in/out, water in/out, CVP and other parameters were measured and compared between the two groups.

RESULTS

One day before symptomatic cerebral vasospasm, three factors reached statistical difference in the group that experienced symptomatic cerebral vasospasm: sodium balance, urine volume and water balance. On the day of symptomatic cerebral vasospasm, two factors reached statistical difference: sodium excretion and urine volume. No factor was significantly different 2 days before symptomatic cerebral vasospasm.

DISCUSSION

Symptomatic cerebral vasospasm has a strong relationship with CSWS. Negative sodium and water balance and increased urine volume indicate a predictor of symptomatic cerebral vasospasm. To predict symptomatic cerebral vasospasm, strict observations are required, because CSWS and symptomatic cerebral vasospasm which follows, develop rapidly.

Multimodality monitoring in neurocritical care

Multimodality monitoring of cerebral physiology encompasses the application of different monitoring techniques and integration of several measured physiologic and biochemical variables into assessment of brain metabolism, structure, perfusion, and oxygenation status. Novel monitoring techniques include transcranial Doppler ultrasonography, neuroimaging, intracranial pressure, cerebral perfusion, and cerebral blood flow monitors, brain tissue oxygen tension monitoring, microdialysis, evoked potentials, and continuous electroencephalogram. Multimodality monitoring enables immediate detection and prevention of acute neurologic injury as well as appropriate intervention based on patients' individual disease states in the neurocritical care unit. Real-time analysis of cerebral physiologic, metabolic, and cardiovascular parameters simultaneously has broadened knowledge about complex brain pathophysiology and cerebral hemodynamics. Integration of this information allows for more precise diagnosis and optimization of management of patients with brain injury.

Early cerebral hemodynamic alternations in patients operated on the first, second and third day after aneurysmal subarachnoid hemorrhage

Surgery timing after aneurysmal subarachnoid hemorrhage (SAH) may influence the risk of vasospasm after early surgical procedure and is correlated with SAH extensiveness. A group consisting of 127 patients with aneurysmal SAH was studied. The changes of mean flow velocity (MFV) were measured in middle cerebral artery (MCA) and in anterior cerebral artery (ACA) by transcranial Doppler sonography (TCD) in three groups of patients divided according to the surgery timing (on the first, second and third day after SAH). Changes of MFV values in MCA and in ACA were similar in all groups. MFV values in the group of patients operated on the third day were the lowest and the pathologic values lasted for the shortest time. In patients with massive SAH (Fisher IV group) and mild SAH (Fisher II group), the lowest MFV values were observed, if patients were operated within 24 hours after SAH. In patients without SAH (Fisher I group), the MFV values were the lowest, if they were operated on the third day after SAH. In patients with severe SAH (Fisher III group), the lowest risk of vasospasm was observed, if they were operated on the second day after SAH; however, the highest risk was found in patients operated on the first day after SAH. Our study suggests: (1) in patients with severe SAH operated on the second day, the lowest risk of vasospasm was observed, and the highest risk of vasospasm was observed if those were operated on the first day; (2) the highest risk of vasospasm was observed in patients operated within 24 hours with mild and massive SAH and in patients without SAH operated on the third day after SAH.

Clinical review: Prevention and therapy of vasospasm in subarachnoid hemorrhage

Vasospasm is one of the leading causes of morbidity and mortality following aneurysmal subarachnoid hemorrhage (SAH). Radiographic vasospasm usually develops between 5 and 15 days after the initial hemorrhage, and is associated with clinically apparent delayed ischemic neurological deficits (DID) in one-third of patients. The pathophysiology of this reversible vasculopathy is not fully understood but appears to involve structural changes and biochemical alterations at the levels of the vascular endothelium and smooth muscle cells. Blood in the subarachnoid space is believed to trigger these changes. In addition, cerebral perfusion may be concurrently impaired by hypovolemia and impaired cerebral autoregulatory function. The combined effects of these processes can lead to reduction in cerebral blood flow so severe as to cause ischemia leading to infarction. Diagnosis is made by some combination of clinical, cerebral angiographic, and transcranial doppler ultrasonographic factors. Nimodipine, a calcium channel antagonist, is so far the only available therapy with proven benefit for reducing the impact of DID. Aggressive therapy combining hemodynamic augmentation, transluminal balloon angioplasty, and intra-arterial infusion of vasodilator drugs is, to varying degrees, usually implemented. A panoply of drugs, with different mechanisms of action, has been studied in SAH related vasospasm. Currently, the most promising are magnesium sulfate, 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors, nitric oxide donors and endothelin-1 antagonists. This paper reviews established and emerging therapies for vasospasm.

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.

Racial differences in cerebral vasospasm: a systematic review of the literature

OBJECTIVE

Despite a significant body of clinical research and the widespread use of early intervention with aggressive postoperative management, cerebral vasospasm (CV) continues to contribute significantly to the morbidity and mortality of aneurysmal subarachnoid hemorrhage (aSAH). Many studies have evaluated predictive factors, although none to date has investigated a possible difference in the incidence of CV between Asian and white patients. We present a review of the modern aSAH literature to examine the incidence of CV in Japan and Europe, two highly researched populations.

METHODS

A literature search was performed using the Medline and PubMed databases. Studies conducted in Japan or Europe published between 1990 and 2004 that reported an incidence of CV after aSAH were subjected to a thorough review. Data from included studies were categorized by origin (Japan or Europe) and method of CV diagnosis (angiography, delayed ischemic neurological deficit, or new infarct attributable to CV), and then were combined. Recorded incidences then were compared using a chi test, and estimates of the relative risk of vasospasm were computed.

RESULTS

The initial literature search identified 102 studies, and 32 studies met all inclusion criteria. The incidence of vasospasm diagnosed by angiography, delayed ischemic neurological deficit, and computed tomography was significantly greater in Japanese studies (all P < 0.001). The relative risks for Japanese patients as compared with European patients were 2.04, 2.07, and 1.53 for angiographic CV, delayed ischemic neurological deficit, and new infarct, respectively.

CONCLUSION

Patients in Japanese studies were more likely to experience CV after aSAH across diagnostic methods. This may be a manifestation of genetic differences between Japanese and European populations. Clinicians should consider possible patient differences when interpreting CV research conducted in these populations.

Future of brain support: multimodality monitoring

Multimodality monitoring of cerebral physiology encompasses the application of different monitoring techniques and integration of several measured physiological and biochemical variables into the assessment of brain metabolism, structure, perfusion and oxygenation status, in addition to clinical evaluation. Novel monitoring techniques include transcranial Doppler ultrasonography, neuroimaging, intracranial pressure, cerebral perfusion and cerebral blood flow monitors, brain tissue oxygen tension monitoring, microdialysis, evoked potentials and continuous electroencephalography. Multimodality monitoring enables the immediate detection and prevention of acute neurological events, as well as appropriate intervention based on a patient’s individual disease state in the neurocritical care unit. Simultaneous real-time analysis of cerebral physiological, metabolic and cardiovascular parameters has broadened knowledge regarding complex brain pathophysiology and cerebral hemodynamics. Integration of this information allows for a more precise diagnosis and optimization of management of patients with brain injury.

Applications of transcranial Doppler in the ICU: a review

OBJECTIVE

Transcranial Doppler (TCD) ultrasonography is a technique that uses a hand-held Doppler transducer (placed on the surface of the cranial skin) to measure the velocity and pulsatility of blood flow within the intracranial and the extracranial arteries. This review critically evaluates the evidence for the use of TCD in the critical care population.

DISCUSSION

TCD has been frequently employed for the clinical evaluation of cerebral vasospasm following subarachnoid haemorrhage (SAH). To a lesser degree, TCD has also been used to evaluate cerebral autoregulatory capacity, monitor cerebral circulation during cardiopulmonary bypass and carotid endarterectomies and to diagnose brain death. Technological advances such as M mode, colour Doppler and three-dimensional power Doppler ultrasonography have extended the scope of TCD to include other non-critical care applications including assessment of cerebral emboli, functional TCD and the management of sickle cell disease.

CONCLUSIONS

Despite publications suggesting concordance between TCD velocity measurements and cerebral blood flow there are few randomized controlled studies demonstrating an improved outcome with the use of TCD monitoring in neurocritical care. Newer developments in this technology include venous Doppler, functional Doppler and use of ultrasound contrast agents.

Biphasic cerebral blood flow velocity profile in patients with aneurysmal subarachnoid hemorrhage

INTRODUCTION

Increases in cerebral blood flow velocity (CBFV) as measured by transcranial Doppler (TCD) sonography are reflective of cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage (SAH). In serial TCD measurements, some patients exhibit CBFV temporal profiles with two peaks (biphasic). The significance of this finding remains unclear. This retrospective case-control study was conducted to investigate the characteristics and possible predictors of biphasic CBFV profiles.

METHODS

Biphasic CBFV profiles were identified in serial TCD examinations (every 1-2 days) of 182 consecutive patients admitted for aneurysmal SAH based on CBFV profiles of the middle cerebral artery on the side of higher maximum velocity. Patients undergoing angioplasty were excluded. Patients meeting these criteria (study patients) were compared to control patients matched for age and Hunt and Hess grade.

RESULTS

Eighteen patients (9.9%) demonstrated biphasic CBFV profiles. The first CBFV (134 +/- 11 cm/second) peak occurred on post-SAH day 6 +/- 1, and the second peak (148 +/- 12 cm/second) on day 13 +/- 1. Study patients more often exhibited focal (p < 0.05) symptoms at the time of the first peak. No patient deteriorated neurologically at the time of the second peak. No correlation was observed between CBVF and mean arterial pressure or central venous pressure trends.

CONCLUSION

Serial TCD assessment identifies patients with SAH and a biphasic CBFV temporal profile. Although the second peak usually is not associated with a worsening of symptoms, these patients were more likely to exhibit clinical symptoms during the first CBFV peak.

Transcranial Doppler sonography evaluation of anterior cerebral artery hypoplasia or aplasia

BACKGROUND AND PURPOSE

Transcranial Doppler (TCD) sonography is useful to evaluate intracranial arteries, however, interpretation of the TCD results in anterior cerebral artery (ACA) is difficult because of hypoplasia or aplasia. We try to define useful TCD indices and cut-off values to determine the variations of ACA.

METHODS

Consecutive patients who underwent TCD and magnetic resonance angiography (MRA) were included. Patients with cerebrovascular abnormality or inadequate temporal windows were excluded. ACA status was classified as normal (NL), hypoplasia (HP), and aplasia (AP) according to MRA. TCD indices of mean flow velocity (MFV), pulsatility index (PI), ACA/middle cerebral artery (MCA) flow velocity ratio (ACA/MCA FVR), and asymmetry index (AI) of ACA were blindly compared with MRA between three groups.

RESULTS

Two hundred and forty-one patients were included, and 193 patients (80%) were classified as NL, 34 (14%) as HP and 14 (6%) as AP. MFV was significantly lower in HP and AP (p<0.001), however, PI and ACA/MCA FVR were not different. AI was significantly different between NL and HP (21.5% vs. 50.4%), NL and AP (21.5% vs. 105.2%) (p<0.001).

CONCLUSIONS

MFV of ACA should be interpreted with caution for its frequent anatomical variations. AI is useful to differentiate hypoplasia and aplasia from normal ACA with optimal criteria.