Microembolic signals in subarachnoid hemorrhage

Alpha power decrease in quantitative EEG detects development of cerebral infarction after subarachnoid hemorrhage early

OBJECTIVE

In subarachnoid hemorrhage (SAH), transcranial Doppler/color-coded-duplex sonography (TCD/TCCS) is used to detect delayed cerebral ischemia (DCI). In previous studies, quantitative electroencephalography (qEEG) also predicted imminent DCI. This study aimed to compare and analyse the ability of qEEG and TCD/TCCS to early identify patients who will develop later manifest cerebral infarction.

METHODS

We analysed cohorts of two previous qEEG studies. Continuous six-channel-EEG with artefact rejection and a detrending procedure was applied. Alpha power decline of ≥ 40% for ≥ 5 hours compared to a 6-hour-baseline was defined as significant EEG event. Median reduction and duration of alpha power decrease in each channel was determined. Vasospasm was diagnosed by TCD/TCCS, identifying the maximum frequency and days of vasospasm in each territory.

RESULTS

34 patients were included (17 male, mean age 56 ± 11 years, Hunt and Hess grade: I-V, cerebral infarction: 9). Maximum frequencies in TCD/TCCS and alpha power reduction in qEEG were correlated (r = 0.43; p = 0.015). Patients with and without infarction significantly differed in qEEG parameters (maximum alpha power decrease: 78% vs 64%, p = 0.019; summed hours of alpha power decline: 236 hours vs 39 hours, p = 0.006) but showed no significant differences in TCD/TCCS parameters.

CONCLUSIONS

There was a moderate correlation of TCD/TCCS frequencies and qEEG alpha power reduction but only qEEG differentiated between patients with and without cerebral infarction.

SIGNIFICANCE

qEEG represents a non-invasive, continuous tool to identify patients at risk of cerebral infarction.

Cerebral Microembolism in Intracerebral Hemorrhage: A Prospective Case-Control Study

BACKGROUND

Small and remote acute ischemic lesions may occur in up to one-third of patients with spontaneous intracerebral hemorrhage (ICH). Possible mechanisms include cerebral embolism, small vessel disease, blood pressure variability and others. The embolic mechanism has not been adequately studied. Using transcranial Doppler (TCD), we assessed the incidence of spontaneous microembolic signals (MESs) in patients with acute ICH.

METHODS

Twenty acute ICH patients were prospectively evaluated within 48 h of hospital admission. Clinical and imaging data were collected. Continuous TCD monitoring was performed in both middle cerebral arteries for a one-hour period on days 1, 3 and 7 of hospital admission. Monitoring was performed in the emergency room, ICU or ward, according to patient location. We compared the frequency and risk factors for MES in patients with ICH and in 20 age- and gender-matched controls without history of ischemic or hemorrhagic stroke.

RESULTS

The mean age was 57.5 ± 14.1 years, and 60% were male. MESs were detected in 7 patients with ICH and in one control patient without ICH (35% vs 5%, p = 0.048). The frequency of MES on day 1 was 15% (3 of 20 patients), on day 3, 26% (5 of 19 patients) and on day 7, 37.5% (3 of 8 patients). Among patients with ICH, those with MES had a tendency to higher frequencies of dyslipidemia (83% vs 33%, p = 0.13) and lobar location of hemorrhages (71% vs 30%, p = 0.15). Two out of 6 patients with ICH who also underwent MRI had remote DWI lesions, of whom one showed MES on TCD.

CONCLUSION

Micro-embolic signals occur in over one-third of patients with ICH. Further research is needed to identify the sources of cerebral microembolism and their relationship with small acute infarcts in ICH.

Quantitative EEG After Subarachnoid Hemorrhage Predicts Long-Term Functional Outcome

PURPOSE

Delayed cerebral ischemia is a major complication after subarachnoid hemorrhage. Our previous study showed that alpha power reduction in continuous quantitative EEG predicts delayed cerebral ischemia. In this prospective cohort, we aimed to determine the prognostic value of alpha power in quantitative EEG for the long-term outcome of patients with subarachnoid hemorrhage.

METHODS

Adult patients with nontraumatic subarachnoid hemorrhage were included if admitted early enough for EEG to start within 72 hours after symptom onset. Continuous six-channel EEG was applied. Unselected EEG signals underwent automated artifact rejection, power spectral analysis, and detrending. Alpha power decline of ≥40% for ≥5 hours was defined as critical EEG event based on previous findings. Six-month outcome was obtained using the modified Rankin scale.

RESULTS

Twenty-two patients were included (14 male; mean age, 59 years; Hunt and Hess grade I-IV; duration of EEG monitoring, median 14 days). Poor outcome (modified Rankin scale, 2-5) was noted in 11 of 16 patients (69%) with critical EEG events. All six patients (100%) without EEG events achieved an excellent outcome (modified Rankin scale 0, 1) (P = 0.0062; sensitivity 100%, specificity 54.5%). Vasospasm detected with transcranial Doppler/Duplex sonography appeared 1.5 days after EEG events and showed weaker association with outcome (P = 0.035; sensitivity 100%, specificity 45.5%). There was no significant association between EEG events and ischemic lesions on imaging (P = 0.1). Also, no association between ischemic lesions and outcome was seen (P = 0.64).

CONCLUSIONS

Stable alpha power in quantitative EEG reflects successful therapy and predicts good functional outcome after subarachnoid hemorrhage. Critical alpha power reduction indicates an increased risk of poor functional outcome.

Unique Contribution of Haptoglobin and Haptoglobin Genotype in Aneurysmal Subarachnoid Hemorrhage

Survivors of cerebral aneurysm rupture are at risk for significant morbidity and neurological deficits. Much of this is related to the effects of blood in the subarachnoid space which induces an inflammatory cascade with numerous downstream consequences. Recent clinical trials have not been able to reduce the toxic effects of free hemoglobin or improve clinical outcome. One reason for this may be the inability to identify patients at high risk for neurologic decline. Recently, haptoglobin genotype has been identified as a pertinent factor in diabetes, sickle cell, and cardiovascular disease, with the Hp 2-2 genotype contributing to increased complications. Haptoglobin is a protein synthesized by the liver that binds free hemoglobin following red blood cell lysis, and in doing so, prevents hemoglobin induced toxicity and facilitates clearance. Clinical studies in patients with subarachnoid hemorrhage indicate that Hp 2-2 patients may be a high-risk group for hemorrhage related complications and poor outcome. We review the relevance of haptoglobin in subarachnoid hemorrhage and discuss the effects of genotype and expression levels on the known mechanisms of early brain injury (EBI) and cerebral ischemia after aneurysm rupture. A better understanding of haptoglobin and its role in preventing hemoglobin related toxicity should lead to novel therapeutic avenues.

An introduction to the pathophysiology of aneurysmal subarachnoid hemorrhage

Pathophysiological processes following subarachnoid hemorrhage (SAH) present survivors of the initial bleeding with a high risk of morbidity and mortality during the course of the disease. As angiographic vasospasm is strongly associated with delayed cerebral ischemia (DCI) and clinical outcome, clinical trials in the last few decades focused on prevention of these angiographic spasms. Despite all efforts, no new pharmacological agents have shown to improve patient outcome. As such, it has become clear that our understanding of the pathophysiology of SAH is incomplete and we need to reevaluate our concepts on the complex pathophysiological process following SAH. Angiographic vasospasm is probably important. However, a unifying theory for the pathophysiological changes following SAH has yet not been described. Some of these changes may be causally connected or present themselves as an epiphenomenon of an associated process. A causal connection between DCI and early brain injury (EBI) would mean that future therapies should address EBI more specifically. If the mechanisms following SAH display no causal pathophysiological connection but are rather evoked by the subarachnoid blood and its degradation production, multiple treatment strategies addressing the different pathophysiological mechanisms are required. The discrepancy between experimental and clinical SAH could be one reason for unsuccessful translational results.

Embolic signals during routine transcranial Doppler ultrasonography in aneurysmal subarachnoid hemorrhage

INTRODUCTION

Cerebral emboli may occur in subarachnoid hemorrhage (SAH) and intracranial aneurysm surgery. Although embolic signs (ES) have been reported in SAH, their origin remains unclear. The aim of this study was to report the detection of ES during routine TCD monitoring in patients with aneurysmal SAH.

METHODS

A total of 105 patients with aneurysmal SAH were submitted to TCD evaluation. Patients were monitored almost daily (5 times per week). In each monitoring session, one experienced operator performed TCD to detect or assess vasospasm and ES in arteries of the Willis polygon.

RESULTS

Four patients out of a total of 105 patients with aneurysmal SAH were found to present spontaneous cerebral embolization during routine TCD monitoring. The average age of the 4 patients (mean ± standard deviation) was 59.5 ± 8.34 years (range 49-68 ys); female patients predominated representing 75% (3/4) of subjects.

CONCLUSION

Although detection of ES was relatively rare in this study, rates of emboli occurrence may be higher under systematic monitoring. The detection of ES after SAH surgery reinforces the need to study the role of embolus in this condition and may be an indicator for prophylactic antithrombotic treatment.

Microembolic Signals in Patients with Systemic Lupus Erythematosus

Introduction:

Central nervous system (CNS) involvement is a common and less understood aspect of systemic lupus erythematosus (SLE). Microembolic signals (MES) have been reported in SLE. We conducted a prospective study to evaluate the frequency of MES among patients with CNS involvement and those without. The main aim of the study is to clarify the pathophysiology of the CNS involvement in SLE.

Methods and Materials:

Sixty eight patients with a diagnosis of SLE (60 females, 8 males) participated in the study. Both middle cerebral arteries were monitored using transcranial Doppler for 60 min to detect MES. All cases underwent neurology and psychiatry assessments.

Results:

MES were detected in 7/68 patients (10.3%) with the mean number of 3.5 per hour. MES were significantly higher in patients with CNS involvement (6/24, 25%) than those without (1/44, 2.2%) (P=0.006). SLE disease activity index, duration of disease, plaque formation, intima-media thickness, and antiphospholipid antibodies were not associated with MES. MES were more frequent in patients receiving Aspirin and/or Warfarin (p=0.02).

Conclusions:

MES may be a predictor for CNS involvement in SLE patients at risk for neuropsychiatric syndromes. Cerebral embolism may be implicated in the pathophysiology of neuropsychiatric SLE.

The relationship between delayed infarcts and angiographic vasospasm after aneurysmal subarachnoid hemorrhage

BACKGROUND

Delayed cerebral ischemia is common after aneurysmal subarachnoid hemorrhage (aSAH) and is a major contributor to poor outcome. Yet, although generally attributed to arterial vasospasm, neurological deterioration may also occur in the absence of vasospasm.

OBJECTIVE

To determine the relationship between delayed infarction and angiographic vasospasm and compare the characteristics of infarcts related to vasospasm vs those unrelated.

METHODS

A retrospective review of patients with aSAH admitted from July 2007 through June 2011. Patients were included if they were admitted within 48 hours of SAH, had a computed tomography scan both 24 to 48 hours following aneurysm treatment and ≥7 days after SAH, and had a catheter angiogram to evaluate for vasospasm. Delayed infarcts seen on late computed tomography but not postprocedurally were attributed to vasospasm if there was moderate or severe vasospasm in the corresponding vascular territory on angiography. Infarct volume was measured by perimeter tracing.

RESULTS

Of 276 aSAH survivors, 134 had all imaging requisite for inclusion. Fifty-four (34%) had moderate or severe vasospasm, of whom 17 (31%) had delayed infarcts, compared with only 3 (4%) of 80 patients without vasospasm (P < .001). There were a total of 29 delayed infarcts in these 20 patients; 21 were in a territory with angiographic vasospasm, but 8 (28%) were not. Infarct volume did not differ between vasospasm-related (18 ± 25 mL) and vasospasm-unrelated (11 ± 12 mL) infarcts (P = .54), but infarcts in the absence of vasospasm were more likely watershed (50% vs. 10%, P = .03).

CONCLUSION

Delayed infarcts following aSAH can occur in territories without angiographic vasospasm and are more likely watershed in distribution.

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.

Coexistence of vasospasm and microembolism detected by transcranial Doppler ultrasonography in a patient with subarachnoid haemorrhage

Delayed cerebral ischaemia as a clinical expression of vasospasm is one of the main complications of subarachnoid haemorrhage. In some cases, ischaemic manifestations can be related to cerebral emboli, but the relationship between vasospasm, damaged endothelial lining, and embolism, remains to be proven. The case is presented of a 56-year-old female patient who, 5 days after the clipping of an aneurysm in the left middle cerebral artery (MCA), suffered transient ischaemic attacks (TIAs) of this arterial territory. Transcranial Doppler ultrasonography showed an increment of the left MCA mean flow velocity, and 12 microembolic signals were detected in 30 mins. The coexistence of microemboli signals with severe vasospasm in the same arterial segment might suggest a causal relationship between cerebral embolism, severity of vasospasm, and TIAs.