Unifying theory of carotid plaque disruption based on structural phenotypes and forces expressed at the lumen/wall interface

OBJECTIVES

To integrate morphological, haemodynamic and mechanical analysis of carotid atheroma driving plaque disruption.

MATERIALS AND METHODS

First, we analysed the phenotypes of carotid endarterectomy specimens in a photographic dataset A, and matched them with the likelihood of preoperative stroke. Second, laser angioscopy was used to further define the phenotypes in intact specimens (dataset B) and benchmark with histology. Third, representative vascular geometries for each structural phenotype were analysed with Computational Fluid Dynamics (CFD), and the mechanical strength of the complicated atheroma to resist penetrating forces was quantified (n=14).

RESULTS

In dataset A (n=345), ulceration (fibrous cap disruption) was observed in 82% of all plaques, intraplaque haemorrhage in 68% (93% subjacent to an ulcer) and false luminal formation in 48%. At least one of these 'rupture' phenotypes was found in 97% of symptomatic patients (n=69) compared with 61% in asymptomatic patients. In dataset B (n=30), laser angioscopy redemonstrated the structural phenotypes with near-perfect agreement with histology. In CFD, haemodynamic stress showed a large pulse magnitude, highest upstream to the point of maximal stenosis and on ulceration the inflow stream excavates the necrotic core cranially and then recirculates into the true lumen. Based on mechanical testing (n=14), the necrotic core is mechanically weak and penetrated by the blood on fibrous cap disruption.

CONCLUSIONS

Fibrous cap ulceration, plaque haemorrhage and excavation are sequential phenotypes of plaque disruption resulting from the chiselling effect of haemodynamic forces over unmatched mechanical tissue strength. This chain of events may result in thromboembolic events independently of the degree of stenosis.

Cerebrovascular Reserve (CVR) and Stages of Hemodynamic Compromise

The concept of hemodynamic compromise (HC) is used to detect brain regions under ischemic stress by impaired ability to dilate in response to a vasodilatory challenge for cerebrovascular reserve (CVR). The vasodilatory challenges are either inhaled CO2 or a carbonic anhydrase inhibitor acetazolamide (AZ) with measurements of cerebral blood flow (CBF) before and during the challenge. The rationale for CVR is that the brain under ischemic stress is vasodilated and the increase in CBF is attenuated. However, regional oxygen extraction fraction (OEF) by positron emission tomography (PET) is the gold standard for measurement of HC. We showed a strong correlation between CVR and OEF and the OEF response (OEFR) before and after vasodilation in patients with acute ischemic stroke. These observations suggest that CVR measurements alone identify brain regions under ischemic stress without the need for expensive, time consuming and difficult PET OEF.

Emerging Pharmacologic Targets in Cerebral Cavernous Malformation and Potential Strategies to Alter the Natural History of a Difficult Disease: A Review

Importance

Cerebral cavernous malformations (CCMs) are vascular lesions of the brain that may lead to hemorrhage, seizures, and neurologic deficits. Most are linked to loss-of-function mutations in 1 of 3 genes, namely CCM1 (originally called KRIT1), CCM2 (MGC4607), or CCM3 (PDCD10), that can either occur as sporadic events or are inherited in an autosomal dominant pattern with incomplete penetrance. Familial forms originate from germline mutations, often have multiple intracranial lesions that grow in size and number over time, and cause an earlier and more severe presentation. Despite active preclinical research on a few pharmacologic agents, clinical translation has been slow. Open surgery and, in some cases, stereotactic radiosurgery remain the only effective treatments, but these options are limited by lesion accessibility and are associated with nonnegligible rates of morbidity and mortality.

Observations

We discuss the limits of CCM management and introduce findings from in vitro and in vivo studies that provide insight into CCM pathogenesis and indicate molecular mechanisms as potential therapeutic targets. These studies report dysregulated cellular pathways shared between CCM, cardiovascular diseases, and cancer. They also suggest the potential effectiveness of proper drug repurposing in association with, or as an alternative to, targeted interventions.

Conclusions and Relevance

We propose methods to exploit specific molecular pathways to design patient-tailored therapeutic approaches in CCM, with the aim to alter its natural progression. In this scenario, the lack of effective pharmacologic options remains a critical barrier that poses an unfulfilled and urgent medical need.

Abstract WP171: Hemodynamic Compromise Identified by Oxygen Extraction Fraction Response (OEFR) to Acetazolamide in Stroke Patients With Large Vessel Occlusion

Hemodynamic compromise identified by cerebrovascular reserve (CVR) and oxygen extraction fraction (OEF) in stroke patients with large artery occlusion is an independent predictor of stroke risk ranging from 27 to 57%. However, comparison of both methods indicates that the sensitivity of CVR is substantially greater than OEF in detecting hemodynamic compromise which may be because CVR includes a vasodilator challenge with acetazolamide as opposed to OEF made in the resting state. We hypothesized that the response of OEF (OEFR) to an acetazolamide challenge would better correlate with CVR than OEF. We examined the correlation between CVR and OEFR to acetazolamide in stroke patients with large artery occlusion.

Methods: Stroke patients with large artery occlusion (internal carotid or middle cerebral artery) were studied by positron emission tomography (PET) using H2 15O2 (water) for cerebral blood flow (CBF) and 15O2 (gas) for cerebral metabolic rate for oxygen before and after acetazolamide. CVR was calculated as: CVR (%) = [(CBFa- CBFb)/CBFb] X 100; where: CBFb = CBF before acetazolamide, CBFa = CBF after acetazolamide. OEF response (OEFR) was similarly calculated as: OEFR (%) = [(OEFa-OEFb)/OEFb]X100; for the entire middle cerebral artery territory of each hemisphere.

Results: There was a highly significant (P=0.0001) negative linear correlation between CVR and OEFR indicating increasing ischemic stress (Figure). Hemispheres from three patients showed a positive OEFR.

Discussion: A positive OEFR in response to a cerebrovascular challenge definitively indicates hemodynamic compromise and eliminates the problem of deciding on the absolute threshold for OEF to signify hemodynamic compromise. A negative OEFR reflects sufficient cerebrovascular reserve relative to oxygen demand.

ACCESS to Better Health and Clear Skies: Telemedicine and Greenhouse Gas Reduction

Introduction: This study estimates the reduction in greenhouse gas (GHG) emissions resulting from 2,020 neuro-emergent telemedicine consultations. We then estimate potential GHG reduction if the program was expanded nationwide. Materials and Methods: Travel distances in miles were calculated for each avoided patient transfer using hospital location data and ArcGIS^® tools. Potential GHG reductions from program expansion were calculated based on state and national stroke Diagnosis-Related Groups (DRGs). Along with average flight distance from a rural hospital to closest level one trauma center. Results: Participation in the Access to Critical Cerebral Emergent Support Services (ACCESS) from May 2015 to July 2017 resulted in 2,020 consultations. Of these consultations, there was a 70% (1,414) reduction in patient transfers. Emission reduction totaled 618,772 kg of carbon dioxide equivalents (CO₂e) (618.77 metric tons) or 0.306 metric tons of CO₂e per patient. Expanding the program across New Mexico and similar U.S. areas resulted in potential reductions of 4,307 (IQR 3,386-5,274) and 213,279 (IQR 169,320-263,570) metric tons of CO₂e. Conclusion: Transport accounts for 26% of global CO₂ emissions and is one of the few industrial sectors where emissions are still growing. What makes this study more impactful is that aviation's emissions are not part of the Kyoto Protocol and little is being done in this sector. GHG reduction was not the main intention of the ACCESS program, but it has shown to be a significant by-product.

MRI-Guided High-Intensity Focused Ultrasound as an Emerging Therapy for Stroke: A Review

Stroke, either ischemic or hemorrhagic, accounts for significantly high morbidity and mortality rates around the globe effecting millions of lives annually. For the past few decades, ultrasound has been extensively investigated to promote clot lysis for the treatment of stroke, myocardial infarction, and acute peripheral arterial occlusions, with or without the use of tPA or contrast agents. In the age of modern minimal invasive techniques, magnetic resonance imaging-guided high-intensity focused ultrasound is a new emerging modality that seems to promise therapeutic utilities for both ischemic and hemorrhagic stroke. High-intensity focused ultrasound causes thermal heating as the tissue absorbs the mechanical energy transmitted by the ultrasonic waves leading to tissue denaturation and coagulation. Several in-vitro and in-vivo studies have demonstrated the viability of this technology for sonothrombolysis in both types of stroke and have warranted clinical trials. Apart from safety and efficacy, initiation of trials would further enable answers regarding its practical application in a clinical setup. Though this technology has been under study for treatment of various brain diseases for some decades now, relatively very few neurologists and even neurosurgeons seem to be acquainted with it. The aim of this review is to provide basic understanding of this powerful technology and discuss its clinical application and potential role as an emerging viable therapeutic option for the future management of stroke.

Middle Cerebral Artery Aneurysm "Neck Overhang": Decreased Postclipping Residual Using the Intersecting Clipping Technique

BACKGROUND

Middle cerebral artery (MCA) aneurysms continue to be viewed by many as primarily surgical entities.

OBJECTIVE

To introduce a new, easily measurable dimension termed "neck overhang," defined as the amount of the aneurysm that extends proximal to the 2 dimensionally defined "neck" and to evaluate the utility of the intersecting clipping technique (use of straight clip and intersecting fenestrated clip) to adapt to this overhanging segment's specific dimensions and achieve better obliteration of the MCA aneurysms.

METHODS

We reviewed retrospectively 100 MCA aneurysms treated surgically over the last 10 yr at our institution. We identified the clipping technique that was performed (intersecting vs "standard" technique) and we evaluated the presence of a postoperative remnant. We then correlated these with the aneurysm's overhanging neck length.

RESULTS

Forty-three aneurysms were treated with the intersecting clipping technique. The overall rate of remnant was 16%. In the standard group, the rate of remnant was 23%, whereas with intersecting clipping that was 7% (P = .029). Within the standard clipping group, we found that the optimum threshold for length of the neck overhang was ≥1.9 mm in order to predict the occurrence of residual. Applying this threshold to the intersecting clipping technique group resulted in a reduction in remnant from 35% in the standard group to 9%.

CONCLUSION

Neck overhang >1.9 mm is associated with a higher chance of postclipping residual aneurysm in MCA aneurysms. The intersecting clipping technique is a versatile technique that can conform to various aneurysms' geometry and can reduce the rate of post clipping residual for aneurysms with high neck overhang.

Cost-effectiveness of Access to Critical Cerebral Emergency Support Services (ACCESS): a neuro-emergent telemedicine consultation program

AIMS

Access to Critical Cerebral Emergency Support Services (ACCESS) was developed as a low-cost solution to providing neuro-emergent consultations to rural hospitals in New Mexico that do not offer comprehensive stroke care. ACCESS is a two-way audio-visual program linking remote emergency department physicians and their patients to stroke specialists. ACCESS also has an education component in which hospitals receive training from stroke specialists on the triage and treatment of patients. This study assessed the clinical and economic outcomes of the ACCESS program in providing services to rural New Mexico from a healthcare payer perspective.

METHODS

A decision tree model was constructed using findings from the ACCESS program and existing literature, the likelihood that a patient will receive a tissue plasminogen activator (tPA), cost of care, and resulting quality adjusted life years (QALYs). Data from the ACCESS program includes emergency room patients in rural New Mexico from May 2015 to August 2016. Outcomes and costs have been estimated for patients who were taken to a hospital providing neurological telecare and patients who were not.

RESULTS

The use of ACCESS decreased neuro-emergent stroke patient transfers from rural hospitals to urban settings from 85% to 5% (no tPA) and 90% to 23% (tPA), while stroke specialist reading of patient CT/MRI imaging within 3 h of onset of stroke symptoms increased from 2% to 22%. Results indicate that use of ACCESS has the potential to save $4,241 ($3,952-$4,438) per patient and increase QALYs by 0.20 (0.14-0.22). This increase in QALYs equates to ∼73 more days of life at full health. The cost savings and QALYs are expected to increase when moving from a 90-day model to a lifetime model.

CONCLUSION

The analysis demonstrates potential savings and improved quality-of-life associated with the use of ACCESS for patients presenting to rural hospitals with acute ischemic stroke (AIS).

Effect of Cerebrospinal Fluid Drainage on Brain Tissue Oxygenation in Traumatic Brain Injury

The effectiveness of cerebrospinal fluid (CSF) drainage in lowering high intracranial pressure (ICP) is well established in severe traumatic brain injury (TBI). Recently, however, the use of external ventricular drains (EVDs) and ICP monitors in TBI has come under question. The aim of this retrospective study was to investigate the effect of CSF drainage on brain tissue oxygenation (PbtO₂). Using a multi-modality monitoring system, we continuously monitored PbtO₂ and parenchymal ICP during CSF drainage events via a ventriculostomy in 40 patients with severe TBI. Measurements were time-locked continuous recordings on a Component Neuromonitoring System in a neuroscience intensive care unit. We further selected for therapeutic CSF drainage events initiated at ICP values above 25 mm Hg and analyzed the 4-min periods before and after drainage for the physiologic variables ICP, cerebral perfusion pressure (CPP), and PbtO₂. We retrospectively identified 204 CSF drainage events for ICP EVD-opening values greater than 25 mm Hg in 23 patients. During the 4 min of opened EVD, ICP decreased by 5.7 ± 0.6 mm Hg, CPP increased by 4.1 ± 1.2 mm Hg, and PbtO₂ increased by 1.15 ± 0.26 mm Hg. ICP, CPP, and PbtO₂ all improved with CSF drainage at ICP EVD-opening values above 25 mm Hg. Although the average PbtO₂ changes were small, a clinically significant change in PbtO₂ of 5 mm Hg or greater occurred in 12% of CSF drainage events, which was correlated with larger decreases in ICP, displaying a complex relationship between ICP and PbtO₂ that warrants further studies.

Complicated Mild Traumatic Brain Injury and the Need for Imaging Surveillance

OBJECTIVE

To evaluate the need for repeat head computed tomography (CT) in patients with complicated mild traumatic brain injury (TBI) determined nonoperative after the first head CT.

METHODS

A total of 380 patients with mild TBI and a positive head CT not needing surgery were included. Changes between first and second head CT were categorized as decreased, increased, or stable.

RESULTS

Three patients required neurosurgical intervention (0.8%) after the second CT. There were no significant differences in demographics including age, gender, alcohol consumption, anticoagulation status, time between first and second CT, Glasgow Coma Scale score at admission and discharge, and incidence of subarachnoid hemorrhage, epidural hematoma, contusion, or skull fractures between the operated and nonoperated groups. All patients in the operated group had subdural hematoma compared with 40.8% in the nonoperated group (P = 0.07). All operated patients showed symptoms of neurologic worsening after initial head CT, compared with 2.7% in the nonoperated group (P < 0.001). Moreover, patients who showed neurologic worsening were more likely to show increased intracranial bleeding on repeat head CT, whereas patients who did not show neurologic worsening were more likely to show decreased or stable intracranial bleeding (P = 0.04).

CONCLUSIONS

Routine repeat head CT in patients with complicated mild TBI is very low yield to predict need for delayed surgical intervention. Instead, serial neurologic examination and observation over the first 8 hours after the injury is recommended. A second CT scan should be obtained only in patients who have neurologic worsening.

Cortical spreading depression occurs during elective neurosurgical procedures

OBJECTIVE

Cortical spreading depression (CSD) has been observed with relatively high frequency in the period following human brain injury, including traumatic brain injury and ischemic/hemorrhagic stroke. These events are characterized by loss of ionic gradients through massive cellular depolarization, neuronal dysfunction (depression of electrocorticographic [ECoG] activity) and slow spread (2–5 mm/min) across the cortical surface. Previous data obtained in animals have suggested that even in the absence of underlying injury, neurosurgical manipulation can induce CSD and could potentially be a modifiable factor in neurosurgical injury. The authors report their initial experience with direct intraoperative ECoG monitoring for CSD.

METHODS

The authors prospectively enrolled patients undergoing elective craniotomy for supratentorial lesions in cases in which the surgical procedure was expected to last > 2 hours. These patients were monitored for CSD from the time of dural opening through the time of dural closure, using a standard 1 × 6 platinum electrode coupled with an AC or full-spectrum DC amplifier. The data were processed using standard techniques to evaluate for slow potential changes coupled with suppression of high-frequency ECoG propagating across the electrodes. Data were compared with CSD validated in previous intensive care unit (ICU) studies, to evaluate recording conditions most likely to permit CSD detection, and identify likely events during the course of neurosurgical procedures using standard criteria.

RESULTS

Eleven patients underwent ECoG monitoring during elective neurosurgical procedures. During the periods of monitoring, 2 definite CSDs were observed to occur in 1 patient and 8 suspicious events were detected in 4 patients. In other patients, either no events were observed or artifact limited interpretation of the data. The DC-coupled amplifier system represented an improvement in stability of data compared with AC-coupled systems. Compared with more widely used postoperative ICU monitoring, there were additional challenges with artifact from saturation during bipolar cautery as well as additional noise peaks detected.

CONCLUSIONS

CSD can occur during elective neurosurgical procedures even in brain regions distant from the immediate operative site. ECoG monitoring with a DC-coupled full-spectrum amplifier seemed to provide the most stable signal despite significant challenges to the operating room environment. CSD may be responsible for some cases of secondary surgical injury. Though further studies on outcome related to the occurrence of these events is needed, efforts to decrease the occurrence of CSD by modification of anesthetic regimen may represent a novel target for study to increase the safety of neurosurgical procedures.

Co-prescription of naloxone as a Universal Precautions model for patients on chronic opioid therapy-Observational study

BACKGROUND

The epidemic of lethal prescription opioid overdose is one of the most pressing public health problems in the United States. In an ambulatory clinic setting, current practice guidelines suggest that health care providers should screen patient's aberrant drug-related behaviors. Given the difficulty of predicting which patients on chronic opioid therapy (COT) will experience opioid overdose, a new paradigm of harm reduction is called for. In previous studies, naloxone, an opioid antagonist, was given only to high-risk patients. However, if naloxone is co-prescribed in a Universal Precautions manner for all patients receiving COT, this may have a significant impact on intentional and unintentional opioid overdose deaths.

METHODS

Adult patients treated with COT for chronic noncancer pain are eligible study participants at the University of New Mexico Pain Center. The primary goal of this 1-year study was to develop an efficient Universal Precautions model for co-prescribing of naloxone with COT in the ambulatory clinic setting. Outcome measures included demographic data, detailed medical and substance use history, current morphine equivalent dose (MED), other "high-risk" medications used, and opioid misuse risk.

RESULTS

One hundred and sixty-four patients were enrolled in this study. All subjects were educated about the risks of opioid overdose and provided naloxone rescue kits. No overdoses occurred in the study population. Follow-up data illustrated that approximately 57% of the cohort had depressive disorder, the median MED was 90 mg/day, and the median Current Opioid Misuse Measure score (COMM) was 5.0.

CONCLUSIONS

The ambulatory co-prescribing of naloxone in a Universal Precautions model for all patients prescribed COT can be adopted as a useful public health intervention. This study illustrates a model that can be used to educate patients, caregivers, and an interdisciplinary team of health care professionals in an academic medical center.

A novel single twist-drill access device for multimodal intracranial monitoring: a 5-year single-institution experience

BACKGROUND

Multimodal intracranial monitoring in the neurosurgical patient requires insertion of probes through multiple craniostomies.

OBJECTIVE

To report our 5-year experience with a novel device allowing multimodal monitoring though a single twist-drill hole.

METHODS

All devices (Hummingbird Synergy, Innerspace) were placed at the Kocher point between 2008 and 2013 at our institution. An independent clinical research nurse prospectively collected data on all bedside placements. Placement accuracy was graded on computed tomography scan as grade 1 (ipsilateral frontal horn or third ventricle), grade 2 (contralateral lateral ventricle), and grade 3 (anywhere else). Infection was monitored with serial cerebrospinal fluid samples.

RESULTS

Two hundred seventy-five devices (198 at bedside, 77 in operating room) were placed in patients with spontaneous subarachnoid hemorrhage (49%), traumatic brain injury (47%), and others (4%) for a median duration of 6 days. A junior (postgraduate year 1-2), midlevel (postgraduate year 3-4), or senior resident (postgraduate year 5-6) placed 39%, 32%, and 29% of the devices, respectively. Ninety-two percent of all devices placed were draining cerebrospinal fluid, ie, were grade 1 (75%) or 2 (17%). Placement accuracy did not vary with level of training. Complications included hemorrhage (10%) and infection (4%), with 1 patient requiring intraparenchymal hematoma evacuation and a second requiring abscess drainage. These rates were lower than reported in the literature for standard external ventricular drains.

CONCLUSION

Hummingbird Synergy is a novel single-port access device for multimodal intracranial monitoring that can be placed safely at the bedside or in the operating room with placement accuracy and has a complication profile similar to or better than that for standard external ventricular drains.

Enhancement of neurogenesis and memory by a neurotrophic peptide in mild to moderate traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a risk factor for Alzheimer disease (AD), a neurocognitive disorder with similar cellular abnormalities. We recently discovered a small molecule (Peptide 6) corresponding to an active region of human ciliary neurotrophic factor, with neurogenic and neurotrophic properties in mouse models of AD and Down syndrome.

OBJECTIVE

To describe hippocampal abnormalities in a mouse model of mild to moderate TBI and their reversal by Peptide 6.

METHODS

TBI was induced in adult C57Bl6 mice using controlled cortical impact with 1.5 mm of cortical penetration. The animals were treated with 50 nmol/d of Peptide 6 or saline solution for 30 days. Dentate gyrus neurogenesis, dendritic and synaptic density, and AD biomarkers were quantitatively analyzed, and behavioral tests were performed.

RESULTS

Ipsilateral neuronal loss in CA1 and the parietal cortex and increase in Alzheimer-type hyperphosphorylated tau and A-β were seen in TBI mice. Compared with saline solution, Peptide 6 treatment increased the number of newborn neurons, but not uncommitted progenitor cells, in dentate gyrus by 80%. Peptide 6 treatment also reversed TBI-induced dendritic and synaptic density loss while increasing activity in tri-synaptic hippocampal circuitry, ultimately leading to improvement in memory recall on behavioral testing.

CONCLUSION

Long-term treatment with Peptide 6 enhances the pool of newborn neurons in the dentate gyrus, prevents neuronal loss in CA1 and parietal cortex, preserves the dendritic and synaptic architecture in the hippocampus, and improves performance on a hippocampus-dependent memory task in TBI mice. These findings necessitate further inquiry into the therapeutic potential of small molecules based on neurotrophic factors.

Comparison of parenchymal and ventricular intracranial pressure readings utilizing a novel multi-parameter intracranial access system

Introduction

Both ventricular and parenchymal devices are available for measurement of intracranial pressure (ICP). The Hummingbird^® Synergy Ventricular System is a novel device allowing multi-parametric neurological monitoring, including both ventricular and parenchymal ICP. The purpose of this study is to compare the congruence of the device’s ventricular and parenchymal ICP readings.

Methods

This single-center, quantitative, interventional study compared parenchymal and ventricular ICP readings from 35 patients with the Hummingbird^® System. If a difference of > ± 3 mmHg existed between an individual patient’s parenchymal and ventricular values, progressive intervention strategies were applied to correct identified issues.

Results

From a total of 2,259 observations, statistical analysis revealed congruence (within ±0-3 mmHg) of 93% of readings comparing parenchymal and ventricular ICP. Of the observations requiring intervention, 58% involved the parenchymal component, 30% involved the ventricular component, and 12% involved both components. Following prescribed interventions, 98% of readings became congruent (within ±0-3 mmHg). The adjusted mean difference between the two methods was -0.95 (95% CI: -0.97,-0.93) mmHg and all mean ICP readings fell between -2 and 2 mmHg.

Conclusion

The Hummingbird^® Synergy Ventricular System demonstrates congruence between ventricular and parenchymal ICP measurements within accepted parameters. Interventions required to realign parenchymal and ventricular readings serve as reminders to clinicians to be vigilant with catheter/cable connections and to maintain appropriate positioning of the ventricular drainage system. The results of this study support the recommendation to use the parenchymal ICP component for routine ICP monitoring, allowing dedication of the ventricular catheter to drainage of cerebrospinal fluid (CSF).

Primary melanocytic tumors of the central nervous system: Report of two cases and review of literature

Background:

Primary melanocytic tumors of the central nervous system (CNS) represent only 1% of all melanomas. We report two rare cases of primary diffuse leptomeningeal melanomatosis (PDLM; case 1) and primary melanoma of the thoraco-lumbar spine (case 2).

Case Description:

In case 1, multiple cerebrospinal fluid (CSF) studies and a brain biopsy were non-diagnostic, with a biopsy of the cauda equina eventually demonstrating malignant melanomatosis. Diagnosis of primary spinal cord melanoma was more straightforward in case 2 with imaging and biopsy.

Conclusion:

PDLM and primary intramedullary spinal melanoma are rare variants of primary CNS melanoma. This report contrasts the diagnostic challenges between the two entities and alerts the neurosurgeon into considering the diagnosis with appropriate clinical presentation.

A novel use of transfer function estimation for early assessment of brain injury outcome

Normal blood flow in the brain as a response to pressure fluctuations is commonly referred to as cerebral autoregulation. Linear, nonparametric models of cerebral autoregulation were estimated for 77 human subjects afflicted with brain injury, with mean arterial pressure used as input, and invasively measured regional cerebral blood flow used as output. The data were continuously monitored from the beginning of subject hospital stay. Mean transfer function gain as a function of frequency was calculated for each subject over a limited time window spanning 48 h, starting postsurgery. The mean transfer function gain of the cerebral autoregulation model provided a highly accurate, statistically significant, assessment of patient outcome. Subjects were accurately grouped by outcome, with a high significance ( ) across the entire measurement spectrum (0.005-0.25 Hz). In addition, the frequency band from 0.1 to 0.25 Hz contains particularly low variance in transfer function gain. This spectral region provides a highly statistically significant ( ) assessment of brain injury patient health that is useful for outcome prediction.

Increased cerebral oxygen metabolism and ischemic stress in subjects with metabolic syndrome-associated risk factors: preliminary observations

Hypertension, diabetes, obesity, and dyslipidemia are risk factors that characterize metabolic syndrome (MetS), which increases the risk for stroke by 40%. In a preliminary study, our aim was to evaluate cerebrovascular reactivity and oxygen metabolism in subjects free of vascular disease but with one or more of these risk factors. Volunteers (n=15) 59±15 (mean±SD)years of age clear of cerebrovascular disease by magnetic resonance angiography but with one or more risk factors were studied by quantitative positron emission tomography for measure ment of cerebral blood flow, oxygen consumption, oxygen extraction fraction (OEF), and acetazolamide cerebrovascular reactivity. Eight of ten subjects with MetS risk factors had OEF >50%. None of the five without risk factors had OEF >50%. The presence of MetS risk factors was highly correlated with OEF >50% by Fisher's exact test (p<0.007). The increase in OEF was significantly (P<0.001) correlated with cerebral metabolic rate for oxygen. Increased OEF was not associated with compromised acetazolamide cerebrovascular reactivity. Subjects with one or more MetS risk factors are characterized by increased cerebral oxygen consumption and ischemic stress, which may be related to increased risk of cerebrovascular disease and stroke.

High-speed real-time resting-state FMRI using multi-slab echo-volumar imaging

We recently demonstrated that ultra-high-speed real-time fMRI using multi-slab echo-volumar imaging (MEVI) significantly increases sensitivity for mapping task-related activation and resting-state networks (RSNs) compared to echo-planar imaging (Posse et al., 2012). In the present study we characterize the sensitivity of MEVI for mapping RSN connectivity dynamics, comparing independent component analysis (ICA) and a novel seed-based connectivity analysis (SBCA) that combines sliding-window correlation analysis with meta-statistics. This SBCA approach is shown to minimize the effects of confounds, such as movement, and CSF and white matter signal changes, and enables real-time monitoring of RSN dynamics at time scales of tens of seconds. We demonstrate highly sensitive mapping of eloquent cortex in the vicinity of brain tumors and arterio-venous malformations, and detection of abnormal resting-state connectivity in epilepsy. In patients with motor impairment, resting-state fMRI provided focal localization of sensorimotor cortex compared with more diffuse activation in task-based fMRI. The fast acquisition speed of MEVI enabled segregation of cardiac-related signal pulsation using ICA, which revealed distinct regional differences in pulsation amplitude and waveform, elevated signal pulsation in patients with arterio-venous malformations and a trend toward reduced pulsatility in gray matter of patients compared with healthy controls. Mapping cardiac pulsation in cortical gray matter may carry important functional information that distinguishes healthy from diseased tissue vasculature. This novel fMRI methodology is particularly promising for mapping eloquent cortex in patients with neurological disease, having variable degree of cooperation in task-based fMRI. In conclusion, ultra-high-real-time speed fMRI enhances the sensitivity of mapping the dynamics of resting-state connectivity and cerebro-vascular pulsatility for clinical and neuroscience research applications.

Lack of functional patency of the lamina terminalis after fenestration following clipping of anterior circulation aneurysms

OBJECT

Fenestration of the lamina terminalis (FLT) during aneurysm surgery for subarachnoid hemorrhage can, in theory, improve CSF circulation from the lateral and third ventricles to the cortical subarachnoid space, which may, in turn, decrease the incidence of hydrocephalus and vasospasm. However, the actual effects of FLT on CSF circulation have been difficult to determine, due to confounding factors. In addition, it is unclear whether the lamina terminalis remains functionally patent when the brain resumes its normal position. The goal of this study was to assess the functional patency of the fenestrated lamina terminalis in patients who underwent surgery for ruptured aneurysms.

METHODS

This prospective study included 15 patients who underwent surgical clipping of ruptured anterior circulation aneurysms, with FLT performed during surgery. On postoperative Day 1, the external ventricular drain of each patient was closed, and 1 ml of Omnipaque 300, an iodine based contrast agent, was injected intraventricularly, accompanied by cranial maneuvering designed to position the contrast agent adjacent to the lamina terminalis. Three to 5 minutes after cranial maneuvering, the flow of contrast agent into the basal cisterns was assessed with CT imaging. Flow was verified by an increase in Hounsfield units in a prespecified "region of interest" within the basal cisterns on the CT scan. This procedure was performed using a standardized protocol designed in consultation with the Department of Radiology and approved by the institutional review board. One patient who underwent endoscopic third ventriculostomy was recruited as a positive control to validate the technique, and 1 patient who underwent aneurysm clipping but not FLT was recruited as a negative control.

RESULTS

Seventeen patients consented to study participation. In the 15 patients who underwent aneurysm clipping and FLT, and the negative control patient who underwent aneurysm clipping but not FLT, the contrast agent followed the normal ventricular pathway from the lateral ventricles into the fourth ventricle, and did not appear in the basal cisterns. In the positive control patient, the contrast agent robustly and immediately filled the basal cisterns.

CONCLUSIONS

Fenestration of the lamina terminalis did not result in functional patency of the lamina terminalis when performed as part of surgical clipping for ruptured aneurysms.

Guidelines for the early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

The authors present an overview of the current evidence and management recommendations for evaluation and treatment of adults with acute ischemic stroke. The intended audiences are prehospital care providers, physicians, allied health professionals, and hospital administrators responsible for the care of acute ischemic stroke patients within the first 48 hours from stroke onset. These guidelines supersede the prior 2007 guidelines and 2009 updates.

METHODS

Members of the writing committee were appointed by the American Stroke Association Stroke Council's Scientific Statement Oversight Committee, representing various areas of medical expertise. Strict adherence to the American Heart Association conflict of interest policy was maintained throughout the consensus process. Panel members were assigned topics relevant to their areas of expertise, reviewed the stroke literature with emphasis on publications since the prior guidelines, and drafted recommendations in accordance with the American Heart Association Stroke Council's Level of Evidence grading algorithm.

RESULTS

The goal of these guidelines is to limit the morbidity and mortality associated with stroke. The guidelines support the overarching concept of stroke systems of care and detail aspects of stroke care from patient recognition; emergency medical services activation, transport, and triage; through the initial hours in the emergency department and stroke unit. The guideline discusses early stroke evaluation and general medical care, as well as ischemic stroke, specific interventions such as reperfusion strategies, and general physiological optimization for cerebral resuscitation.

CONCLUSIONS

Because many of the recommendations are based on limited data, additional research on treatment of acute ischemic stroke remains urgently needed.

Xenon-enhanced computed tomography cerebral blood flow measurements in acute cerebral ischemia: Review of 56 cases

OBJECTIVE

Ischemic stroke must be diagnosed promptly if patients are to be treated with thrombolytic therapy. The diagnosis of acute cerebral ischemia, however, is usually based on clinical and computed tomography (CT) scan findings. CT scans are often normal in the first few hours after stroke. The purpose of this study was to determine whether Xenon-enhanced CT (XeCT) cerebral blood flow (CBF) studies could increase the sensitivity of stroke detection in the acute stage.

METHODS

CBF studies performed within 8 hours of symptom onset were evaluated in 56 patients who presented with hemispheric stroke symptoms. Mean CBF in the symptomatic vascular territory was calculated and compared with the corresponding contralateral area. CBF values below 18 mL/100g/min on 2 adjacent regions of interest were considered ischemic lesions. CT scans and angiograms were compared with the XeCt findings. Neurological condition on admission and discharge was evaluated by using National Institutes of Health Stroke Scale (NIHSS) scores.

RESULTS

The mean NIHSS score on admission was 12+/-5. Early CT scans were abnormal in 28 (50%) patients. There were 9 (16%) patients who had normal XeCT scans because of spontaneous reperfusion of the ischemic area. XeCT studies showed an ischemic lesion in 47 (84%) patients. In these patients, the mean CBF in the affected vascular territory was 16+/-8 mL/100g/min compared with 35+/-13 mL/100g/min in the contralateral specular territory (P<0.001). There were no false positive or negative XeCT studies, and the location of the perfusion defect corresponded with the CT and/or angiographic findings in all cases. Eight patients died (14%), and the 48 survivors (86%) had a mean NIHSS score of 9+/-6 on discharge.

CONCLUSIONS

CBF measurements were correlated with the CT and angiographic results and greatly assisted in the diagnosis of acute ischemic stroke. XeCT studies used for estimating the location and extent of cerebral ischemia may be important in the triage of patients for acute stroke therapy.

Outcome prediction within twelve hours after severe traumatic brain injury by quantitative cerebral blood flow

We measured quantitative cortical mantle cerebral blood flow (CBF) by stable xenon computed tomography (CT) within the first 12 h after severe traumatic brain injury (TBI) to determine whether neurologic outcome can be predicted by CBF stratification early after injury. Stable xenon CT was used for quantitative measurement of CBF (mL/100 g/min) in 22 cortical mantle regions stratified as follows: low (0-8), intermediate (9-30), normal (31-70), and hyperemic (>70) in 120 patients suffering severe (Glasgow Coma Scale [GCS] score ≤8) TBI. For each of these CBF strata, percentages of total cortical mantle volume were calculated. Outcomes were assessed by Glasgow Outcome Scale (GOS) score at discharge (DC), and 1, 3, and 6 months after discharge. Quantitative cortical mantle CBF differentiated GOS 1 and GOS 2 (dead or vegetative state) from GOS 3-5 (severely disabled to good recovery; p<0.001). Receiver operating characteristic (ROC) curve analysis for percent total normal plus hyperemic flow volume (TNHV) predicting GOS 3-5 outcome at 6 months for CBF measured <6 and <12 h after injury showed ROC area under the curve (AUC) cut-scores of 0.92 and 0.77, respectively. In multivariate analysis, percent TNHV is an independent predictor of GOS 3-5, with an odds ratio of 1.460 per 10 percentage point increase, as is initial GCS score (OR=1.090). The binary version of the Marshall CT score was an independent predictor of 6-month outcome, whereas age was not. These results suggest that quantitative cerebral cortical CBF measured within the first 6 and 12 h after TBI predicts 6-month outcome, which may be useful in guiding patient care and identifying patients for randomized clinical trials. A larger multicenter randomized clinical trial is indicated.

CT Density Changes with Rapid Onset Acute, Severe, Focal Cerebral Ischemia in Monkeys

Computerized tomography (CT) is the most often used imaging modality in the evaluation of acute clinical stroke. However, the rapidity with which CT density changes occur after acute, severe, focal ischemia cannot be determined clinically. Even if the time of symptom onset is known, clinical stroke severity is highly variable. We studied the time course of CT density change after severe, rapid onset, acute, focal ischemia as documented by stable xenon CT cerebral blood flow (CBF) in monkeys. Eight monkeys (Macaca mulatta) were subjected to transorbital occlusion of the left posterior cerebral, anterior, middle, and internal carotid arteries to induce focal ischemia. CT density Hounsfield units (HU), CBF by stable xenon CT, arterial blood pressure, and blood gases were measured before occlusion, immediately after occlusion, at 30 min, and hourly for up to 6 h. Occlusion of the cerebral arteries decreased CBF to 8 ± 5 ml/100 g/ min within 15 min postocclusion. At 6 h, CBF was unchanged at 9 ± 4 ml/100 g/ min. CT density within the ischemic core fell from 42 to 38 HU immediately after occlusion (P < 0.05), rose transiently, then fell at 2 h (P < 0.01) and plateaued at 36 ± 5 HU for a total decrease of 4-5 HU between 4 and 6 h poststroke. Changes in CT density lag severe focal ischemia by 2 h. Thus, when CT hypodensity is seen in acute stroke, it is likely 2 h old. It also provides an explanation for the phenomenon of clinical CT mismatch with clinical deficits and normal CT.

Failure of cerebral hemodynamic selection in general or of specific positron emission tomography methodology?: Carotid Occlusion Surgery Study (COSS)

BACKGROUND AND PURPOSE

The Carotid Occlusion Surgery Study (COSS) was an improvement over the Extracranial-Intracranial Bypass Study, which did not utilize physiological selection. To assess possible reasons for early closure of the COSS trial, we reviewed COSS methods used to identify high-risk patients and compared results with separate quantitative data.

METHODS

Increased oxygen extraction fraction (OEF) by positron emission tomography is a gold standard for ischemia, but the specific thresholds and equivalency of the semiquantitative OEF ratio utilized in COSS and quantitative OEF are at issue.

RESULTS

The semiquantitative hemispheric OEF ratio used in COSS did not identify the same group of patients as did quantitative OEF using a threshold of 50%.

CONCLUSIONS

The failure of COSS is likely caused by a failure of the semiquantitative, hemispheric OEF ratio method rather than by the selection for bypass based on hemodynamic compromise.

Timing treatment of a giant intracranial aneurysm by the use of magnetic resonance imaging for the determination of intraluminal clot stability

A 44-year-old man presented with a giant intracranial carotid artery aneurysm. Magnetic resonance (MR) images demonstrated a large amount of fresh intraluminal thrombus in the aneurysm. During test occlusion of the internal carotid artery using an endovascular balloon positioned in the cervical portion of the internal carotid, the patient sustained an apparent embolic episode. The patient was followed for several weeks with serial MR imaging until the thrombus had lysed. Repeat test occlusion followed by permanent carotid occlusion was uneventful. Serial MR evaluations of intraluminal thrombus in large aneurysms might help to determine an optimal time for institution of intervention.

Complications of preoperative balloon test occlusion of the internal carotid arteries: experience in 300 cases

Treatment of some tumors and aneurysms of the skull base may require internal carotid artery (ICA) sacrifice. Preoperatively to determine the dependence of the cerebral blood flow on a particular vessel, we perform a balloon test occlusion (BTO) by temporarily occluding the vessel in an awake patient. During occlusion, clinical evaluations and cerebral blood flow measurements are assessed. We have performed 300 BTOs. Eleven patients (3.7%) have had complications. Six (2%) were asymptomatic dissections. Five (1.7%) had neurologic deficits that persisted beyond the test period. Of these five, one was back to baseline in less than 24 hours, one recovered completely in a week, and one (0.33%) had a minimal but persistent dysphasia. These latter three cases are unexplained but might have resulted from unrecognized dissections or embolic events. Finally, one patient with a persistent deficit required energency surgery for reasons unrelated to the BTO and was therefore difficult to assess, and one required emergency middle cerebral artery embolectomy and repair of the dissection. The preoperative knowledge of carotid dependence in cases in which the ICA is at risk is essential, since vascular grafts or alternative surgical approaches are necessary in patients unable to tolerate carotid sacrifice. Since approximately 15 to 20% of the population falls into this category, a preoperative BTO appears justified.

Xenon-enhanced cerebral blood flow at 28% xenon provides uniquely safe access to quantitative, clinically useful cerebral blood flow information: a multicenter study

BACKGROUND AND PURPOSE

Xe-CT measures CBF and can be used to make clinical treatment decisions. Availability has been limited, in part due to safety concerns. Due to improvements in CT technology, the concentration of inhaled xenon gas has been decreased from 32% to 28%. To our knowledge, no data exist regarding the safety profile of this concentration. We sought to better determine the safety profile of this lower concentration through a multicenter evaluation of adverse events reported by all centers currently performing xenon/CT studies in the US.

MATERIALS AND METHODS

Patients were prospectively recruited at 7 centers to obtain safety and efficacy information. All studies were performed to answer a clinical question. All centers used the same xenon delivery system. CT imaging was used during a 4.3-minute inhalation of 28% xenon gas. Vital signs were monitored on all patients throughout each procedure. Occurrence and severity of adverse events were recorded by the principal investigator at each site.

RESULTS

At 7 centers, 2003 studies were performed, 1486 (74.2%) in nonventilated patients. The most common indications were occlusive vascular disease and ischemic stroke; 93% of studies were considered clinically useful. Thirty-nine studies (1.9%) caused respiratory suppression of >20 seconds, all of which resolved spontaneously. Shorter respiratory pauses occurred in 119 (5.9%), and hyperventilation, in 34 (1.7%). There were 53 additional adverse events (2.9%), 7 of which were classified as severe. No adverse event resulted in any persistent neurologic change or other sequelae.

CONCLUSIONS

Xe-CT CBF can be performed safely, with a very low risk of adverse events and, to date, no risk of permanent morbidity or sequelae. On the basis of the importance of the clinical information gained, Xe-CT should be made widely available.

Portable head computed tomography scanner--technology and applications: experience with 3421 scans

OBJECTIVE

The use of head computed tomography (CT) is standard in the management of acute brain injury; however, there are inherent risks of transport of critically ill patients. Portable CT can be brought to the patient at any location.

METHODS

We describe the clinical use of a portable head CT scanner (CereTom: NeuroLogica: Danvers, MA) that can be brought to the patient's bedside or to other locations such as the operating room or angiography suite.

RESULTS

Between June of 2006 and December of 2009, a total of 3421 portable CTs were performed. A total of 3278 (95.8%) were performed in the neuroscience intensive care unit (ICU) for an average of 2.6 neuroscience ICU CT scans per day. Other locations where CTs were performed included other ICUs (n = 97), the operating room (n = 53), the emergency department (n = 1), and the angiography suite (n = 2). Most studies were non-contrasted head CT, though other modalities including xenon/CT, contrasted CT, and CT angiography were performed.

CONCLUSION

Portable head CT can reliably and consistently be performed at the patient's bedside. This should lead to decreased transportation-related morbidity and improved rapid decision making in the ICU, OR, and other locations. Further studies to confirm this clinical advantage are needed.

Diagnosis of ventriculoperitoneal shunt infection using [F-18]-FDG PET: a case report

Infection of cerebrospinal fluid (CSF) shunts is a common occurrence and can often be difficult to diagnose using standard analysis of shunt fluid. This article presents the first case report on the diagnosis of a CSF shunt infection on FDG PET scan. A 26-year-old female underwent ventriculoperitoneal shunt placement after developing a pseudomeningocele subsequent to a suboccipital craniectomy for Chiari malformation. Two months later, the patient presented with abdominal pain and non-specific symptoms and was found to have a perisplenic abscess for which she was adequately treated. Failure of her symptoms to solve and an initial negative shunt CSF analysis prompted the search for other sources of infection. An FDG PET scan performed a week later found evidence of increase tracer uptake around the distal tip of the catheter and a repeat shunt CSF analysis showed evidence of CSF infection. FDG PET may be useful in diagnosing shunt related infections in case of high clinical suspicion when standard diagnostic modalities fail to diagnose hardware infection.

Temporal Chondroblastoma with a Novel Chromosomal Translocation (2;5) (q33;q13)

The case of a 51-year-old man with a large temporal mass is presented. The mass eroded the floor of the middle fossa medially to the sphenoid sinus. A combined approach with neurosurgery and otolaryngology was performed to achieve maximal resection of the mass. Pathology was typical for chondroblastoma: a rare, benign but locally invasive chondroid tumor. Genetic testing revealed a translocation of (2;5) (q33;q13). This is a unique genetic mutation in all chondroid tumors to our knowledge. The diagnostic utility or role of this mutation in the pathobiology of this tumor remains to be determined.

Very early hypothermia induction in patients with severe brain injury (the National Acute Brain Injury Study: Hypothermia II): a randomised trial

BACKGROUND

The inconsistent effect of hypothermia treatment on severe brain injury in previous trials might be because hypothermia was induced too late after injury. We aimed to assess whether very early induction of hypothermia improves outcome in patients with severe brain injury.

METHODS

The National Acute Brain Injury Study: Hypothermia II (NABIS: H II) was a randomised, multicentre clinical trial of patients with severe brain injury who were enrolled within 2·5 h of injury at six sites in the USA and Canada. Patients with non-penetrating brain injury who were 16-45 years old and were not responsive to instructions were randomly assigned (1:1) by a random number generator to hypothermia or normothermia. Patients randomly assigned to hypothermia were cooled to 35°C until their trauma assessment was completed. Patients who had none of a second set of exclusion criteria were either cooled to 33°C for 48 h and then gradually rewarmed or treated at normothermia, depending upon their initial treatment assignment. Investigators who assessed the outcome measures were masked to treatment allocation. The primary outcome was the Glasgow outcome scale score at 6 months. Analysis was by modified intention to treat. This trial is registered with ClinicalTrials.gov, NCT00178711.

FINDINGS

Enrolment occurred from December, 2005, to June, 2009, when the trial was terminated for futility. Follow-up was from June, 2006, to December, 2009. 232 patients were initially randomised a mean of 1·6 h (SD 0·5) after injury: 119 to hypothermia and 113 to normothermia. 97 patients (52 in the hypothermia group and 45 in the normothermia group) did not meet any of the second set of exclusion criteria. The mean time to 35°C for the 52 patients in the hypothermia group was 2·6 h (SD 1·2) and to 33°C was 4·4 h (1·5). Outcome was poor (severe disability, vegetative state, or death) in 31 of 52 patients in the hypothermia group and 25 of 56 in the normothermia group (relative risk [RR] 1·08, 95% CI 0·76-1·53; p=0·67). 12 patients in the hypothermia group died compared with eight in the normothermia group (RR 1·30, 95% CI 0·58-2·52; p=0·52).

INTERPRETATION

This trial did not confirm the utility of hypothermia as a primary neuroprotective strategy in patients with severe traumatic brain injury.

The impact of a telehealth web-based solution on neurosurgery triage and consultation

INTRODUCTION

To enhance the quality of neurosurgery consultations, triage, and transport decisions between a Level I trauma service neurosurgery program at the University of New Mexico Hospital and referring hospitals, a secure Health Insurance Portability and Accountability Act (HIPAA)-compliant Web-based system was developed, to which digital neurological images could be sent for review by a neurosurgeon for consultation or patient transfer. Based upon prior experience of neurosurgery, it was predicted that 25% of transfer requests would be avoided if the neurosurgeons reviewed the computerized tomography scans at the time of a transfer request. In addition, it was predicted in 25% of the case that changes in management recommendations would take place independent of the transfer decision.

METHODS

The program was designed to allow referring hospitals to transmit digital images to the Web site, providing consulting doctors with additional patient information. This project analyzed the neurosurgeons' responses to questions designed to determine if transport or management decisions were altered when using this telehealth program in response to a request for consultation or transfer from a rural facility.

RESULTS

Analysis of the responses of the consulting neurosurgeons revealed that, after viewing the images, 44% of the potential transfers were avoided and 44% of consulted cases resulted in management recommendation changes independent of the transfer decision.

CONCLUSIONS

Use of the system resulted in improved triage and changes in transfer or management recommendations. A significant number of potential transfers were avoided, resulting in transport cost avoidance, more effective use of resources, and more appropriate use of the neurosurgery service as well as improved patient preparation.

Definition of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage as an outcome event in clinical trials and observational studies: proposal of a multidisciplinary research group

BACKGROUND AND PURPOSE

In clinical trials and observational studies there is considerable inconsistency in the use of definitions to describe delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage. A major cause for this inconsistency is the combining of radiographic evidence of vasospasm with clinical features of cerebral ischemia, although multiple factors may contribute to DCI. The second issue is the variability and overlap of terms used to describe each phenomenon. This makes comparisons among studies difficult.

METHODS

An international ad hoc panel of experts involved in subarachnoid hemorrhage research developed and proposed a definition of DCI to be used as an outcome measure in clinical trials and observational studies. We used a consensus-building approach.

RESULTS

It is proposed that in observational studies and clinical trials aiming to investigate strategies to prevent DCI, the 2 main outcome measures should be: (1) cerebral infarction identified on CT or MRI or proven at autopsy, after exclusion of procedure-related infarctions; and (2) functional outcome. Secondary outcome measure should be clinical deterioration caused by DCI, after exclusion of other potential causes of clinical deterioration. Vasospasm on angiography or transcranial Doppler can also be used as an outcome measure to investigate proof of concept but should be interpreted in conjunction with DCI or functional outcome.

CONCLUSIONS

The proposed measures reflect the most relevant morphological and clinical features of DCI without regard to pathogenesis to be used as an outcome measure in clinical trials and observational studies.

Elevation of matrix metalloproteinases 3 and 9 in cerebrospinal fluid and blood in patients with severe traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) causes an increase in matrix metalloproteinases (MMPs), which are associated with neuroinflammation, blood-brain barrier disruption, hemorrhage, and cell death. We hypothesized that patients with TBI have an increase in MMPs in ventricular cerebrospinal fluid (CSF) and plasma.

METHODS

Patients with TBI and a ventricular catheter were entered into the study. Samples of CSF and plasma were collected at the time of catheter placement and at 24 and 72 hours after admission. Seven TBI patients were entered into the study, with 6 having complete data for analysis. Only patients who had a known time of insult that fell within a 6-hour window from initial insult to ventriculostomy were accepted into the study. Control CSF came from ventricular fluid in patients undergoing shunt placement for normal pressure hydrocephalus. Both MMP-2 and MMP-9 were measured with gelatin zymography and MMP-3 with Western immunoblot.

RESULTS

We found a significant elevation in the levels of the latent form of MMP-9 (92-kD) in the CSF obtained at the time of arrival (P < 0.05). Elevated levels of MMP-2 were detected in plasma at 72 hours, but not in the CSF. Using albumin from both CSF and blood, we calculated the MMP-9 index, which was significantly increased in the CSF, indicating endogenous MMP production. Western immunoblot showed elevated levels of MMP-3 in CSF at all times measured, whereas MMP-3 was not detected in the CSF of normal pressure hydrocephalus.

CONCLUSION

We show that MMPs are increased in the CSF of TBI patients. Although the number of patients was small, the results were robust and clearly demonstrated increases in MMP-3 and MMP-9 in ventricular CSF in TBI patients compared with controls. Although these preliminary results will need to be replicated, we propose that MMPs may be important in blood-brain barrier opening and hemorrhage secondary to brain injury in patients.

Reduced stroke risk in patients with compromised cerebral blood flow reactivity treated with superficial temporal artery to distal middle cerebral artery bypass surgery

Extracranial-to-intracranial (EC-IC) bypass surgery for the prevention of stroke in patients with symptomatic carotid artery occlusion has nearly ended after a randomized trial showed no benefit of the procedure. Although an EC-IC bypass might benefit patients with compromised cerebrovascular hemodynamics, the randomized trial did not differentiate patients with hemodynamic from embolic etiologies. However, subsequent investigators have identified a subgroup of patients at increased stroke risk from hemodynamic compromise.

METHODS

We examined the subsequent stroke rate of 42 patients with symptomatic carotid occlusion at high risk for stroke identified as having a baseline cerebral blood flow (CBF)<45 mL/100 g/min and a >5% CBF reduction in one vascular territory after a vasodilatory challenge from 1 g of intravenous acetazolamide on stable xenon-computed tomography (CT) CBF imaging.

RESULTS

Thirty patients (group 1) treated medically were a subgroup with carotid occlusion from our long-term natural history study. During a median follow-up of 12 months, 9 patients (30%) had a new stroke within a median of 5 months. Twelve patients (group 2) had recurrent, disabling cerebral ischemic symptoms, with 8 progressing to mild fixed neurological deficits from deep white matter infarction identified on CT. All were treated with superficial temporal artery to distal middle cerebral artery (STA-MCA) bypass with restoration of cerebrovascular reserve postoperatively; none had a stroke during the 18-month minimum follow-up (P=.041). Perioperative morbidity included subendocardial infarction in one and a small, asymptomatic left frontal hemorrhage in another patient. Early postoperative and delayed xenon/CT CBF studies obtained a median of 5 months postoperatively showed maintenance of cerebrovascular reserve.

CONCLUSION

STA-MCA bypass surgery can restore cerebrovascular reserve in high-risk patients with symptomatic internal carotid artery occlusion. This was achieved with minimal perioperative complications, resulting in a subsequent reduction of stroke frequency. We suggest that the efficacy of STA-MCA bypass surgery for symptomatic carotid occlusion be re-examined prospectively using hemodynamic selection criteria.

Cerebellar haemangioblastoma: temporising treatment in a high risk pregnancy

We describe the case of a young woman who was 29 weeks pregnant and presented with preterm labour along with hydrocephalus and brain stem symptoms from a large cytic lesion associated with a precariously sited haemangioblastoma. Cyst drainage was initially employed, with an Ommaya reservoir and periodic percutaneous drainage until the patient could undergo a full-term delivery. Following delivery, the tumour was embolised and resected surgically in the following week. The patient had no new deficits following surgery. We believe this temporising approach for symptomatic haemangioblastomas discovered in high risk pregnancies can lead to a better outcome for the mother and child.