Continuous monitoring of cerebrovascular pressure reactivity in patients with head injury

Object

Cerebrovascular pressure reactivity is the ability of cerebral vessels to respond to changes in transmural pressure. A cerebrovascular pressure reactivity index (PRx) can be determined as the moving correlation coefficient between mean intracranial pressure (ICP) and mean arterial blood pressure.

Methods

The authors analyzed a database consisting of 398 patients with head injuries who underwent continuous monitoring of cerebrovascular pressure reactivity. In 298 patients, the PRx was compared with a transcranial Doppler ultrasonography assessment of cerebrovascular autoregulation (the mean index [Mx]), in 17 patients with the PET–assessed static rate of autoregulation, and in 22 patients with the cerebral metabolic rate for O2. Patient outcome was assessed 6 months after injury.

Results

There was a positive and significant association between the PRx and Mx (R2 = 0.36, p < 0.001) and with the static rate of autoregulation (R2 = 0.31, p = 0.02). A PRx > 0.35 was associated with a high mortality rate (> 50%). The PRx showed significant deterioration in refractory intracranial hypertension, was correlated with outcome, and was able to differentiate patients with good outcome, moderate disability, severe disability, and death. The graph of PRx compared with cerebral perfusion pressure (CPP) indicated a U–shaped curve, suggesting that too low and too high CPP was associated with a disturbance in pressure reactivity. Such an optimal CPP was confirmed in individual cases and a greater difference between current and optimal CPP was associated with worse outcome (for patients who, on average, were treated below optimal CPP [R2 = 0.53, p < 0.001] and for patients whose mean CPP was above optimal CPP [R2 = −0.40, p < 0.05]). Following decompressive craniectomy, pressure reactivity initially worsened (median −0.03 [interquartile range −0.13 to 0.06] to 0.14 [interquartile range 0.12–0.22]; p < 0.01) and improved in the later postoperative course. After therapeutic hypothermia, in 17 (70.8%) of 24 patients in whom rewarming exceeded the brain temperature threshold of 37°C, ICP remained stable, but the average PRx increased to 0.32 (p < 0.0001), indicating significant derangement in cerebrovascular reactivity.

Conclusions

The PRx is a secondary index derived from changes in ICP and arterial blood pressure and can be used as a surrogate marker of cerebrovascular impairment. In view of an autoregulation–guided CPP therapy, a continuous determination of a PRx is feasible, but its value has to be evaluated in a prospective controlled trial.

Characterisation of carotid atheroma in symptomatic and asymptomatic patients using high resolution MRI

BACKGROUND AND PURPOSE

To prospectively evaluate differences in carotid plaque characteristics in symptomatic and asymptomatic patients using high resolution MRI.

METHODS

20 symptomatic and 20 asymptomatic patients, with at least 50% carotid stenosis as determined by Doppler ultrasound, underwent preoperative in vivo multispectral MRI of the carotid arteries. Studies were analysed both qualitatively and quantitatively in a randomised manner by two experienced readers in consensus, blinded to clinical status, and plaques were classified according to the modified American Heart Association (AHA) criteria.

RESULTS

After exclusion of poor quality images, 109 MRI sections in 18 symptomatic and 19 asymptomatic patients were available for analysis. There were no significant differences in mean luminal stenosis severity (72.9% vs 67.6%; p = 0.09) or plaque burden (median plaque areas 50 mm(2) vs 50 mm(2); p = 0.858) between the symptomatic and asymptomatic groups. However, symptomatic lesions had a higher incidence of ruptured fibrous caps (36.5% vs 8.7%; p = 0.004), haemorrhage or thrombus (46.5% vs 14.0%; p<0.001), large necrotic lipid cores (63.8% vs 28.0%; p = 0.002) and complicated type VI AHA lesions (61.5% vs 28.1%; p = 0.001) compared with asymptomatic lesions. The MRI findings of plaque haemorrhage or thrombus had an odds ratio of 5.25 (95% CI 2.08 to 13.24) while thin or ruptured fibrous cap (as opposed to a thick fibrous cap) had an odds ratio of 7.94 (95% CI 2.93 to 21.51) for prediction of symptomatic clinical status.

CONCLUSIONS

There are significant differences in plaque characteristics between symptomatic and asymptomatic carotid atheroma and these can be detected in vivo by high resolution MRI.

Correlation of carotid atheromatous plaque inflammation using USPIO-enhanced MR imaging with degree of luminal stenosis

BACKGROUND AND PURPOSE

Inflammation is a recognized risk factor for the vulnerable atherosclerotic plaque. The study explores the relationship between the degree of Magnetic Resonance (MR)-defined inflammation using Ultra Small Super-Paramagnetic Iron Oxide (USPIO) particles and the severity of luminal stenosis in asymptomatic carotid plaques.

METHODS

Seventy-one patients with an asymptomatic carotid stenosis of > or = 40% underwent multi-sequence USPIO-enhanced MR imaging. Stenosis severity was measured according to the NASCET and ECST methods.

RESULTS

No demonstrable relationship between inflammation as measured by USPIO-enhanced signal change and the degree of luminal stenosis was found.

CONCLUSIONS

Inflammation and stenosis are likely to be independent risk factors, although this needs to be further validated.

Findings of the International Subarachnoid Aneurysm Trial and the National Study of Subarachnoid Haemorrhage in context

Concern has been expressed about the applicability of the findings of the International Subarachnoid Aneurysm Trial (ISAT) with respect to the relative effects on outcome of coiling and clipping. It has been suggested that the findings of the National Study of Subarachnoid Haemorrhage may have greater relevance for neurosurgical practice. The objective of this paper was to interpret the findings of these two studies in the context of differences in their study populations, design, execution and analysis. Because of differences in design and analysis, the findings of the two studies are not directly comparable. The ISAT analysed all randomized patients by intention-to-treat, including some who did not undergo a repair, and obtained the primary outcome for 99% of participants. The National Study only analysed participants who underwent clipping or coiling, according to the method of repair, and obtained the primary outcome for 91% of participants. Time to repair was also considered differently in the two studies. The comparison between coiling and clipping was susceptible to confounding in the National Study, but not in the ISAT. The two study populations differed to some extent, but inspection of these differences does not support the view that coiling was applied inappropriately in the National Study. Therefore, there are many reasons why the two studies estimated different sizes of effect. The possibility that there were real, systematic differences in practice between the ISAT and the National Study cannot be ruled out, but such explanations must be seen in the context of other explanations relating to chance, differences in design or analysis, or confounding.

Correlation of carotid atheromatous plaque inflammation with biomechanical stress: Utility of USPIO enhanced MR imaging and finite element analysis

OBJECTIVE

The aim of this study was to explore whether there is a relationship between the degree of MR-defined inflammation using ultra small super-paramagnetic iron oxide (USPIO) particles, and biomechanical stress using finite element analysis (FEA) techniques, in carotid atheromatous plaques.

METHODS AND RESULTS

18 patients with angiographically proven carotid stenoses underwent multi-sequence MR imaging before and 36 h after USPIO infusion. T(2)(*) weighted images were manually segmented into quadrants and the signal change in each quadrant normalised to adjacent muscle was calculated after USPIO administration. Plaque geometry was obtained from the rest of the multi-sequence dataset and used within a FEA model to predict maximal stress concentration within each slice. Subsequently, a new statistical model was developed to explicitly investigate the form of the relationship between biomechanical stress and signal change. The Spearman's rank correlation coefficient for USPIO enhanced signal change and maximal biomechanical stress was -0.60 (p=0.009).

CONCLUSIONS

There is an association between biomechanical stress and USPIO enhanced MR-defined inflammation within carotid atheroma, both known risk factors for plaque vulnerability. This underlines the complex interaction between physiological processes and biomechanical mechanisms in the development of carotid atheroma. However, this is preliminary data that will need validation in a larger cohort of patients.

Biological effects of acute pravastatin treatment in patients after aneurysmal subarachnoid hemorrhage: a double-blind, placebo-controlled trial

OBJECT

The authors previously demonstrated that acute pravastatin therapy in patients after aneurysmal subarachnoid hemorrhage (SAH) ameliorates vasospasm-related delayed ischemic neurological deficits. The object of this study was to continue to examine potential mechanisms of these beneficial effects.

METHODS

Eighty patients with aneurysmal SAH (age range 18-84 years; time to onset 1.8 +/- 1.3 days) were enrolled in a double-blind study and randomized to receive 40 mg of oral pravastatin or placebo daily for as long as 14 days. Daily transcranial Doppler ultrasonography and blood tests every 3 days (including full blood cell counts, coagulation profiles, fasting glucose and lipid profiles, and serum biochemistry) were performed during the trial period.

RESULTS

No significant differences were found in baseline laboratory data between the trial groups. Subsequent measurements during the 14-day trial showed reduced low-density lipoprotein (LDL) cholesterol levels and total/high-density lipoprotein cholesterol ratios between Days 3 and 15 (p < 0.05), and increased D-dimer levels (p < 0.05) on Day 6, in the pravastatin group. Patients who received pravastatin but developed vasospasm had significantly lower baseline LDL cholesterol levels or a less extensive reduction in LDL cholesterol levels (p < 0.05), and greater increases in plasma fibrinogen (p = 0.009) and serum C-reactive protein on Day 3 (p = 0.007), compared with those patients without vasospasm. The reduction in LDL cholesterol levels on Day 3 in the placebo group correlated with the duration of normal cerebral autoregulation on the ipsilateral side of the ruptured aneurysm (p = 0.002).

CONCLUSIONS

In addition to functioning through a cholesterol-independent pathway, cerebrovascular protection from acute statin therapy following aneurysmal SAH may also function through cholesterol-dependent mechanisms.

Ventriculostomy for control of raised ICP in acute traumatic brain injury

The aim of this study was to evaluate the effect of ventriculostomy on intracranial pressure (ICP), and related parameters, including cerebrospinal compensation, cerebral oxygenation (PbtO2) and metabolism (microdialysis) in patients with traumatic brain injury (TBI).

MATERIALS AND METHODS

Twenty-four patients with parenchymal ICP sensors were prospectively included in the study. Ventriculostomy was performed after failure to control ICP with initial measures. Monitoring parameters were digitally recorded before and after ventriculostomy and compared using appropriate tests.

RESULTS

In all patients ventriculostomy led to rapid reduction in ICP. Pooled mean daily values of ICP remained < 20mmHg for 72h after ventriculostomy and were lower than before (p < 0.001). In 11 out of 24 patients during the initial 24-h period following ventriculostomy an increase in ICP to values exceeding 20mmHg was observed. In the remaining 13 patients ICP remained stable, allowing reduction in the intensity of treatment. In this group ventriculostomy led to significant improvement in craniospinal compensation (RAP index), cerebral perfusion pressure and PbtO2. Improvement in lactate/pyruvate ratio, a marker of energy metabolism, was correlated with the increase in PbtO2.

CONCLUSION

Ventriculostomy is a useful ICP-lowering manoeuvre, with sustained ICP reduction and related physiological improvements achieved in > 50% of patients.

Comparison of the inflammatory burden of truly asymptomatic carotid atheroma with atherosclerotic plaques contralateral to symptomatic carotid stenosis: an ultra small superparamagnetic iron oxide enhanced magnetic resonance study

BACKGROUND

Inflammation is a recognised risk factor for the vulnerable atherosclerotic plaque. The aim of this study was to explore whether there is a difference in the degree of magnetic resonance (MR) defined inflammation using ultra small superparamagnetic iron oxide (USPIO) particles within carotid atheroma in completely asymptomatic individuals and the asymptomatic carotid stenosis contralateral to the symptomatic side.

METHODS

20 symptomatic patients with contralateral disease and 20 completely asymptomatic patients underwent multi-sequence MR imaging before and 36 h after USPIO infusion. Images were manually segmented into quadrants and signal change in each quadrant was calculated following USPIO administration. Mean signal change was compared across all quadrants in the two groups.

RESULTS

The mean percentage of quadrants showing signal loss was 53% in the contralateral group compared with 31% in completely asymptomatic individuals (p = 0.025). The mean percentages showing enhancement were 44% and 65%, respectively (p = 0.024). The mean signal difference between the two groups was 8.6% (95% CI 1.6% to 15.6%; p = 0.017).

CONCLUSIONS

Truly asymptomatic plaques seem to demonstrate inflammation but not to the extent of the contralateral asymptomatic stenosis to the symptomatic side. Inflammatory activity may be a significant risk factor in asymptomatic disease.

Identifying vulnerable carotid plaques in vivo using high resolution magnetic resonance imaging-based finite element analysis

OBJECT

Individuals with carotid atherosclerosis develop symptoms following rupture of vulnerable plaques. Biomechanical stresses within this plaque may increase vulnerability to rupture. In this report the authors describe the use of in vivo carotid plaque imaging and computational mechanics to document the magnitude and distribution of intrinsic plaque stresses.

METHODS

Ten (five symptomatic and five asymptomatic) individuals underwent plaque characterization magnetic resonance (MR) imaging. Plaque geometry and composition were determined by multisequence review. Intrinsic plaque stress profiles were generated from 3D meshes by using finite element computational analysis. Differences in principal (shear) stress between normal and diseased sections of the carotid artery and between symptomatic and asymptomatic plaques were noted.

RESULTS

There was a significant difference in peak principal stress between diseased and nondiseased segments of the artery (mean difference 537.65 kPa, p < 0.05). Symptomatic plaques had higher mean stresses than asymptomatic plaques (627.6 kPa compared with 370.2 kPa, p = 0.05), which were independent of luminal stenosis and plaque composition.

CONCLUSION

Significant differences in plaque stress exist between plaques from symptomatic individuals and those from asymptomatic individuals. The MR imaging-based computational analysis may therefore be a useful aid to identification of vulnerable plaques in vivo.

Enhancement of cerebral blood flow using systemic hypertonic saline therapy improves outcome in patients with poor-grade spontaneous subarachnoid hemorrhage

OBJECT

Systemic administration of 23.5% hypertonic saline enhances cerebral blood flow (CBF) in patients with poor-grade spontaneous subarachnoid hemorrhage (SAH). Whether the increment of change in CBF correlates with changes in autoregulation of CBF or outcome at discharge remains unknown.

METHODS

Thirty-five patients with poor-grade spontaneous SAH received 2 ml/kg 23.5% hypertonic saline intravenously, and they underwent bedside transcranial Doppler (TCD) ultrasonography and intracranial pressure (ICP) monitoring. Seventeen of them underwent Xe-enhanced computed tomography (CT) scanning for measuring CBF. Outcome was assessed using the modified Rankin Scale (mRS) at discharge from the hospital. The data were analyzed using repeated-measurement analysis of variance and Dunnett correction. A comparison was made between patients with favorable and unfavorable outcomes using multivariate logistic regression.

RESULTS

The authors observed a maximum increase in blood pressure by 10.3% (p < 0.05) and cerebral perfusion pressure (CPP) by 21.2% (p < 0.01) at 30 minutes, followed by a maximum decrease in ICP by 93.1% (p < 0.01) at 60 minutes. Changes in ICP and CPP persisted for longer than 180 and 90 minutes, respectively. The results of TCD ultrasonography showed that the baseline autoregulation was impaired on the ipsilateral side of ruptured aneurysm, and increments in flow velocities were higher and lasted longer on the contralateral side (48.75% compared with 31.96% [p = 0.045] and 180 minutes compared with 90 minutes [p < 0.05], respectively). The autoregulation was briefly impaired on the contralateral side during the infusion. A dose-dependent effect of CBF increments on favorable outcome was seen on Xe-CT scans (mRS Score 1-3, odds ratio 1.27 per 1 ml/100 g tissue x min, p = 0.045).

CONCLUSIONS

Bolus systemic hypertonic saline therapy may be used for reversal of cerebral ischemia to normal perfusion in patients with poor-grade SAH.

Internal Carotid Artery Stenosis: Accuracy of Subjective Visual Impression for Evaluation with Digital Subtraction Angiography and Contrast-enhanced MR Angiography

PURPOSE

To prospectively determine, for both digital subtraction angiography (DSA) and contrast material-enhanced magnetic resonance (MR) angiography, the accuracy of subjective visual impression (SVI) in the evaluation of internal carotid artery (ICA) stenosis, with objective caliper measurements serving as the reference standard.

MATERIALS AND METHODS

Local ethics committee approval and written informed patient consent were obtained. A total of 142 symptomatic patients (41 women, 101 men; mean age, 70 years; age range, 44-89 years) suspected of having ICA stenosis on the basis of Doppler ultrasonographic findings underwent both DSA and contrast-enhanced MR angiography. With each modality, three independent neuroradiologists who were blinded to other test results first visually estimated and subsequently objectively measured stenoses. Diagnostic accuracy and percentage misclassification for correct categorization of 70%-99% stenosis were calculated for SVI, with objective measurements serving as the reference standard. Interobserver variability was determined with kappa statistics.

RESULTS

After exclusion of arteries that were unsuitable for measurement, 180 vessels remained for analysis with DSA and 159 vessels remained for analysis with contrast-enhanced MR angiography. With respect to 70%-99% stenosis, SVI was associated with average misclassification of 8.9% for DSA (8.9%, 7.8%, and 10.0% for readers A, B, and C, respectively) and of 11.7% for contrast-enhanced MR angiography (11.3%, 8.8%, and 15.1% for readers A, B, and C, respectively). Negative predictive values were excellent (92.3%-100%). Interobserver variability was higher for SVI (DSA, kappa = 0.62-0.71; contrast-enhanced MR angiography, kappa = 0.57-0.69) than for objective measurements (DSA, kappa = 0.75-0.80; contrast-enhanced MR angiography, kappa = 0.66-0.72).

CONCLUSION

SVI alone is not recommended for evaluation of ICA stenosis with both DSA and contrast-enhanced MR angiography. SVI may be acceptable as an initial screening tool to exclude the presence of 70%-99% stenosis, but caliper measurements are warranted to confirm the presence of such stenosis.

Predictive value of initial clinical status, intracranial pressure and transcranial Doppler pulsatility after subarachnoid haemorrhage

BACKGROUND

We examined the predictive value of initial clinical status, mean arterial blood pressure (MABP), intracranial pressure (ICP) and transcranial Doppler (TCD)-derived pulsatility and resistance indices for outcome and quality of life one year following aneurysmal subarachnoid haemorrhage (SAH).

METHOD

Neuromonitoring was performed in 29 patients following clipping or coiling of an aneurysm. Mean arterial blood pressure was measured in the radial artery and intracranial pressure was assessed via a closed external ventricular drainage. Based on transcranial Doppler-recordings of the middle cerebral artery, Gosling's pulsatility (PI) and Pourcelot's resistance (RI) index were calculated. Glasgow outcome score (GOS) and short form-36 (SF-36) scores were determined one year after SAH.

FINDINGS

An unfavourable outcome (GOS 1-3) was observed in 34% of patients and correlated significantly (p < 0.05) with a poor initial clinical status, as determined by Glasgow Coma Scale (r = 0.55), Hunt and Hess (r = -0.62), World Federation of Neurosurgical Societies (WFNS) (r = -0.48) and Fisher (r = -0.58) score. Poor outcome was significantly associated with high mean arterial blood pressure (r = -0.44) and intracranial pressure (r = -0.48) as well as increased pulsatility (r = -0.46) and resistance (r = -0.43) indices. Hunt and Hess grade > or = 4 (OR 12.4, 5-95% CI: 1.9-82.3), mean arterial blood pressure > 95 mmHg (19.5, 2.9-132.3), Gosling's pulsatility >0.8 (6.5, 1.6-27.1) and Pourcelot's resistance >0.57 (15.4, 2.3-103.4) were predictive for unfavourable outcome in logistic regression, however TCD-diagnosed vasospasm was not. Except for mental health, significantly reduced scores were observed in all short form-36 domains. Initial clinical status correlated significantly with the physical functioning, role physical, bodily pain, social functioning and physical component summary of short form-36.

CONCLUSIONS

Mortality and morbidity following SAH remains high, especially in poor-grade patients. Outcome is mainly correlated with initial clinical status, mean arterial blood pressure, intracranial pressure, pulsatility and resistance indices. Those factors seem to be stronger than the influence of vasospasm.

Effects of Acute Pravastatin Treatment on Intensity of Rescue Therapy, Length of Inpatient Stay, and 6-Month Outcome in Patients After Aneurysmal Subarachnoid Hemorrhage

Background and Purpose— We have previously demonstrated that acute pravastatin therapy after aneurysmal subarachnoid hemorrhage ameliorates vasospasm-related delayed ischemic deficits. This study assesses the effects of pravastatin on the frequency and intensity for rescue therapy, length of inpatient stay, and long-term outcome at 6 months.

Methods— Eighty aneurysmal subarachnoid hemorrhage patients (age 18 to 84 years, onset 1.8±1.3 days) were randomized to receive daily oral pravastatin (40 mg) or placebo for up to 14 days. Clinical events were recorded during the trial. Six-month outcome was assessed using the Short Form 36 and the modified Rankin Scale.

Results— Although no significant difference in the outcome at discharge was found between the trial groups, multivariate analysis showed pravastatin therapy reduced unfavorable outcome by 73% ( P =0.041). The benefit persisted at 6 months ( P =0.063) and was notable in the physical ( P <0.001) and psychosocial ( P <0.001) aspects measured using Short Form 36. Furthermore, the acute pravastatin therapy reduced the requirement for triple-H therapy (hypertensive, hypervolemic, hemodilution; P =0.045) and mortality related to vasospasm ( P =0.02) and sepsis ( P =0.001); no significant difference was found in the length of inpatient stay between the trial groups.

Conclusions— This trial demonstrates that acute statin treatment reduces traditional rescue therapy for vasospasm after aneurysmal subarachnoid hemorrhage. Improvement in early outcome has proved robust at 6 months, particularly in relation to physical and psychosocial (Short Form 36) outcome.

A randomized trial of synthetic patch versus direct primary closure in carotid endarterectomy

OBJECTIVE

To define whether or not direct microscopic closure with or without the use of a vascular patch is advantageous in terms of clinical outcome and late vessel occlusion rates after microsurgical carotid endarterectomy.

METHODS

Three hundred thirty-eight elective carotid endarterectomies in 315 patients were randomized to direct arteriotomy or closure with a polyester collagen-coated vascular patch. Ten procedures did not follow the randomization process because of technical difficulties and were excluded. Vessel patency (duplex ultrasound) and outcome were assessed during and immediately after surgery and at 4 and 12 months after surgery.

RESULTS

Four-month ultrasound assessment (n = 321) identified five occluded vessels: two in the patch group (n = 149) and three in the direct closure group (n = 172). Six patients in the patch group had died or were significantly disabled at 4 months, compared with five in the direct closure group. At the 12-month assessment (n = 313), eight vessels had occluded: five from the patched group (n = 146) and three from the direct closure group (n = 167). Eight patients in the patch group had died or were significantly disabled, compared with four in the direct closure group. No statistically significant difference between the two groups in terms of vessel occlusion, morbidity, or mortality was seen (P > 0.1).

CONCLUSION

No difference in vessel patency and clinical outcome has been identified after microscopic patch angioplasty and direct arteriotomy repair. The authors conclude that there is no benefit from the routine use of patch angioplasty in microscopic carotid endarterectomy.

Tissue oxygen index: thresholds for cerebral ischemia using near-infrared spectroscopy

BACKGROUND AND PURPOSE

To date, the clinical application of near infrared spectroscopy in the adult brain has been limited. The NIRO 300 (Hamamatsu Photonics) provides a continuous measurement of tissue oxygen index (TOI) using spatially resolved spectroscopy. Although TOI reflects cerebral oxygenation to a high degree of sensitivity and specificity, to become a useful clinical tool, thresholds for cerebral ischemia need to be defined. This study has attempted to identify a quantifiable TOI threshold for ischemia in the adult brain.

METHODS

One hundred sixty-seven patients undergoing carotid endarterectomy were studied. The NIRO 300 was incorporated into an established multimodal monitoring system enabling observations of cerebral hemodynamic changes under highly controlled conditions. Changes in TOI (%DeltaTOI) on clamping the internal carotid artery were compared with intracranial blood flow (middle cerebral artery flow velocity) and cerebral function monitoring to identify and quantify periods of cerebral ischemia.

RESULTS

Significant correlation was seen between changes in middle cerebral artery flow velocity and DeltaTOI on clamping (r=0.74, P=0.0001). Thirty-one patients showed cerebral ischemia on internal carotid artery clamping as defined by a sustained fall in cerebral function monitoring. A threshold for %DeltaTOI of -13 was identified, above which no patients showed any evidence of ischemia on clamping. This threshold provided 100% sensitivity and 93.2% specificity for patients satisfying the preset criteria for cerebral ischemia.

CONCLUSIONS

These data demonstrate the potential to identify TOI-quantified thresholds for cerebral ischemia in the adult brain and thus improve the clinical use of near infrared spectroscopy. Our observations have defined a drop in TOI (13%) that can be adopted as a threshold for severe cerebral ischemia with high sensitivity and specificity.

Effects of acute treatment with statins on cerebral autoregulation in patients after aneurysmal subarachnoid hemorrhage

OBJECT

The authors previously have demonstrated that acute treatment with pravastatin after aneurysmal subarachnoid hemorrhage (SAH) can ameliorate vasospasm-related delayed ischemic neurological deficits (DINDs). In the current study, they test the hypothesis that these effects are associated with improvement in indices describing autoregulation of cerebral blood flow.

METHODS

In this double-blind study, 80 patients between the ages of 18 and 84 years who had aneurysmal SAH were randomized equally to receive either 40 mg of oral pravastatin or placebo once daily for up to 14 days (medication was started 1.8 x 1.3 days after ictus). Autoregulation was measured using a daily transient hyperemic response test (THRT) on transcranial Doppler ultrasonography (800 measurements in 80 patients), and data were compared between the pravastatin and placebo groups and between patients with or without vasospasm, DINDs, or unfavorable outcome. Measurement of autoregulation also was performed using the pressure-reactivity index, a moving correlation coefficient between mean arterial and intracranial pressures (Days 0-5, 132 measurements in 32 patients). There was no difference in baseline autoregulation indices between the trial groups. The members of the pravastatin group not only had a shorter duration of impaired autoregulation but also had stronger transient hyperemic response ratios (THRRs) bilaterally. A negative correlation existed between the mean flow velocity in the middle cerebral artery and THRRs. Onset of DINDs occurred when bilateral autoregulation failed. On Days 3, 4, and 5, the pressure-reactivity index correlated significantly with ipsilateral impaired autoregulation.

CONCLUSIONS

The neuroprotective effects of acute treatment with pravastatin following aneurysmal SAH are associated with enhancement of autoregulation. A routine and daily assessment of cerebral autoregulation by using the THRT may help identify patients at high risk of DINDs.

Impulsivity, reward sensitivity, and decision-making in subarachnoid hemorrhage survivors

Subarachnoid hemorrhage (SAH) survivors often report psychosocial and emotional changes, including a diminished capacity for decision making. However, systematic investigations into the nature of the changes have been limited to those patients surviving SAH secondary to aneurysms of the anterior communicating artery. This study aimed to explore the nature of decision making in survivors of SAH secondary to aneurysms of the middle cerebral or posterior communicating artery using a series of computerized tasks. Twenty SAH survivors and 20 matched controls completed a battery of computerized decision-making tasks. These included tasks examining an individual's ability to make probabilistic choices and risk-taking behavior, as well as tasks examining aspects of impulsivity. The results revealed two key patterns of abnormal decision-making behavior in the SAH survivors: altered sensitivity to both reward and punishment, and impulsive responding. These complex deficits may contribute to difficulties in daily living resulting from apathy, poor judgment, or inhibition in SAH survivors.

Assessment of inflammatory burden contralateral to the symptomatic carotid stenosis using high-resolution ultrasmall, superparamagnetic iron oxide-enhanced MRI

BACKGROUND AND PURPOSE

It is well known that the vulnerable atheromatous plaque has a thin, fibrous cap and large lipid core with associated inflammation. This inflammation can be detected on MRI with use of a contrast medium, Sinerem, an ultrasmall superparamagnetic iron oxide (USPIO). Although the incidence of macrophage activity in asymptomatic disease appears low, we aimed to explore the incidence of MRI-defined inflammation in asymptomatic plaques in patients with known contralateral symptomatic disease.

METHODS

Twenty symptomatic patients underwent multisequence MRI before and 36 hours after USPIO infusion. Images were manually segmented into quadrants, and the signal change in each quadrant was calculated after USPIO administration. A mixed mathematical model was developed to compare the mean signal change across all quadrants in the 2 groups. Patients had a mean symptomatic stenosis of 77% compared with 46% on their asymptomatic side, as measured by conventional angiography.

RESULTS

There were 11 (55%) men, and the median age was 72 years (range, 53 to 84 years). All patients had risk factors consistent with severe atherosclerotic disease. All symptomatic carotid stenoses had inflammation, as evaluated by USPIO-enhanced imaging. On the contralateral sides, inflammatory activity was found in 19 (95%) patients. Contralaterally, there were 163 quadrants (57%) with a signal loss after USPIO when compared with 217 quadrants (71%) on the symptomatic side (P=0.007).

CONCLUSIONS

This study adds weight to the argument that atherosclerosis is a truly systemic disease. It suggests that investigation of the contralateral side in patients with symptomatic carotid stenosis can demonstrate inflammation in 95% of plaques, despite a mean stenosis of only 46%. Thus, inflammatory activity may be a significant risk factor in asymptomatic disease in patients who have known contralateral symptomatic disease. Patients with symptomatic carotid disease should have their contralateral carotid artery followed up.

Decompressive craniectomy in traumatic brain injury: the randomized multicenter RESCUEicp study (www.RESCUEicp.com)

The RESCUEicp (Randomized Evaluation of Surgery with Craniectomy for Uncontrollable Elevation of intracranial pressure) study has been established to determine whether decompressive craniectomy has a role in the management of patients with traumatic brain injury and raised intracranial pressure that does not respond to initial treatment measures. We describe the concept of decompressive craniectomy in traumatic brain injury and the rationale and protocol of the RESCUEicp study.

Treatment of a direct carotid-cavernous fistula in a patient with type IV Ehlers-Danlos syndrome: a novel approach

We report a case of a 34-year-old female with type IV Ehlers-Danlos syndrome diagnosed with a carotid cavernous fistula presenting with progressive proptosis. Endovascular embolization using balloons or coils carries a high risk of complications in this group of patients, owing to the extreme fragility of the blood vessels. Initial treatment was conservative until an intracerebral haemorrhage occurred. To avoid transfemoral angiography, the ipsilateral carotid arteries and the internal jugular vein were surgically exposed for insertion of two endovascular sheaths. The patient was transferred from theatre to the angiography suite and the sheaths were used for embolization access. The fistula was closed, with preservation of the carotid artery, using Guglielmi detachable coils deployed in the cavernous sinus from the arterial and venous sides. Rapid resolution of symptoms and signs followed, which was sustained at 6-month follow-up. This technique offers alternative access for endovascular treatment, which may reduce the high incidence of mortality associated with catheter angiography in this condition.

Identifying inflamed carotid plaques using in vivo USPIO-enhanced MR imaging to label plaque macrophages

BACKGROUND

Inflammation within atherosclerotic lesions contributes to plaque instability and vulnerability to rupture. We set out to evaluate the use of a macrophage labeling agent to identify carotid plaque inflammation by in vivo magnetic resonance imaging (MRI).

METHODS AND RESULTS

Thirty patients with symptomatic severe carotid stenosis scheduled for carotid endarterectomy underwent multi-sequence MRI of the carotid bifurcation before and after injection of ultrasmall superparamagnetic particles of iron oxide (USPIOs). USPIO particles accumulated in macrophages in 24 of 30 plaques (80%). Areas of signal intensity reduction, corresponding to USPIO/macrophage-positive histological sections, were visualized in 24 of 27 (89%) patients, with an average reduction in signal intensity induced by the USPIO particles of 24% (range, 3.1% to 60.8%).

CONCLUSIONS

USPIO-enhanced MRI can identify plaque inflammation in vivo by accumulation of USPIO within macrophages in carotid plaques.

Use of antihypertension agents for the suppression of arterial pulse pressure waveforms in patients with intracranial aneurysms

Object

Patients with intracranial aneurysms tend toward raised blood pressure and abnormal pulse pressure profiles. The authors have investigated the influence of three antihypertension agents on blood pressure and pulse pressure waveforms in patients with known intracranial aneurysms, with a view to assessing the potential benefits of longterm antihypertension therapy on the progression of unruptured intracranial aneurysms.

Methods

Nineteen patients with a mean age of 56 years (range 38–76 years) were recruited for this study. All patients had confirmed intracranial aneurysms. A double-blind, randomized, crossover study was performed using perindopril, irbesartan, isosorbide mononitrate, and a placebo. Blood pressure and pulse pressure waveforms were assessed at the end of each 4-week treatment period.

Perindopril and irbesartan were well tolerated. For all measured parameters except heart rate (p = 0.03), no significant difference between baseline and placebo was identified. Each drug when compared with placebo reduced peripheral arterial blood pressure. Perindopril significantly decreased mean blood pressure by 10 mm Hg (p = 0.004), irbesartan by 9 mm Hg (p = 0.004), and isosorbide mononitrate by 13 mm Hg (p = 0.005).

The administration of each drug effected a significant reduction in the carotid artery augmentation index (AIX) compared with baseline values (perindopril p = 0.01, irbesartan p = 0.0002, and isosorbide mononitrate p = 0.03). There was also a significant difference in the AIX between irbesartan and the placebo (p = 0.05). Compared with the placebo, there was a significant difference in AIX (adjusted for heart rate) following the administration of irbesartan (p = 0.003) and isosorbide mononitrate (p = 0.01), but not with perindopril (p = 0.17).

Conclusions

Irbesartan appears to be the most effective treatment for the combined suppression of blood pressure and AIX in patients with intracranial aneurysms and has a high degree of patient tolerance.