From Text to Insight: A Natural Language Processing-Based Analysis of Topics and Trends in Neurosurgery

BACKGROUND AND OBJECTIVES

Neurosurgical research is a rapidly evolving field, with new research topics emerging continually. To provide a clearer understanding of the evolving research landscape, our study aimed to identify and analyze the prevalent research topics and trends in Neurosurgery.

METHODS

We used BERTopic, an advanced natural language processing-based topic modeling approach, to analyze papers published in the journal Neurosurgery . Using this method, topics were identified based on unique sets of keywords that encapsulated the core themes of each article. Linear regression models were then trained on the topic probabilities to identify trends over time, allowing us to identify "hot" (growing in prominence) and "cold" (decreasing in prominence) topics. We also performed a focused analysis of the trends in the current decade.

RESULTS

Our analysis led to the categorization of 12 438 documents into 49 distinct topics. The topics covered a wide range of themes, with the most commonly identified topics being "Spinal Neurosurgery" and "Treatment of Cerebral Ischemia." The hottest topics of the current decade were "Peripheral Nerve Surgery," "Unruptured Aneurysms," and "Endovascular Treatments" while the cold topics were "Chiari Malformations," "Thromboembolism Prophylaxis," and "Infections."

CONCLUSION

Our study underscores the dynamic nature of neurosurgical research and the evolving focus of the field. The insights derived from the analysis can guide future research directions, inform policy decisions, and identify emerging areas of interest. The use of natural language processing in synthesizing and analyzing large volumes of academic literature demonstrates the potential of advanced analytical techniques in understanding the research landscape, paving the way for similar analyses across other medical disciplines.

Exploiting Natural Language Processing to Unveil Topics and Trends of Traumatic Brain Injury Research

Traumatic brain injury (TBI) has evolved from a topic of relative obscurity to one of widespread scientific and lay interest. The scope and focus of TBI research have shifted, and research trends have changed in response to public and scientific interest. This study has two primary goals: first, to identify the predominant themes in TBI research; and second, to delineate "hot" and "cold" areas of interest by evaluating the current popularity or decline of these topics. Hot topics may be dwarfed in absolute numbers by other, larger TBI research areas but are rapidly gaining interest. Likewise, cold topics may present opportunities for researchers to revisit unanswered questions. We utilized BERTopic, an advanced natural language processing (NLP)-based technique, to analyze TBI research articles published since 1990. This approach facilitated the identification of key topics by extracting sets of distinctive keywords representative of each article's core themes. Using these topics' probabilities, we trained linear regression models to detect trends over time, recognizing topics that were gaining (hot) or losing (cold) relevance. Additionally, we conducted a specific analysis focusing on the trends observed in TBI research in the current decade (the 2020s). Our topic modeling analysis categorized 42,422 articles into 27 distinct topics. The 10 most frequently occurring topics were: "Rehabilitation," "Molecular Mechanisms of TBI," "Concussion," "Repetitive Head Impacts," "Surgical Interventions," "Biomarkers," "Intracranial Pressure," "Posttraumatic Neurodegeneration," "Chronic Traumatic Encephalopathy," and "Blast Induced TBI," while our trend analysis indicated that the hottest topics of the current decade were "Genomics," "Sex Hormones," and "Diffusion Tensor Imaging," while the cooling topics were "Posttraumatic Sleep," "Sensory Functions," and "Hyperosmolar Therapies." This study highlights the dynamic nature of TBI research and underscores the shifting emphasis within the field. The findings from our analysis can aid in the identification of emerging topics of interest and areas where there is little new research reported. By utilizing NLP to effectively synthesize and analyze an extensive collection of TBI-related scholarly literature, we demonstrate the potential of machine learning techniques in understanding and guiding future research prospects. This approach sets the stage for similar analyses in other medical disciplines, offering profound insights and opportunities for further exploration.

Ultra-Early (<5 Hours) Decompression for Thoracolumbar Spinal Cord Injury: A Case Series

Early surgical decompression within 24 hours for traumatic spinal cord injury (SCI) is associated with improved neurological recovery. However, the ideal timing of decompression is still up for debate. The objective of this study was to utilize our retrospective single-institution series of ultra-early (<5 hours) decompression to determine if ultra-early decompression led to improved neurological outcomes and was a feasible target over previously defined early decompression targets. Retrospective data on patients with SCI who underwent ultra-early (<5 hours) decompression at a level one metropolitan trauma center were extracted and collected from 2015-2018. American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade improvement was the primary outcome, with ASIA Motor score improvement and complication rate as secondary outcomes. Four individuals met the criteria for inclusion in this case series. All four suffered thoracolumbar SCI. All patients improved neurologically by AIS grade, and there were no complications directly related to ultra-early surgery. Given the small sample size, there was no statistically significant difference in outcomes compared to a control group who underwent early (5-24 hour) decompression in the same period. Ultra-early decompression is a feasible and safe target for thoracolumbar SCI and may lead to improved neurological outcomes without increased risk of complications. This case series can help create the foundation for future, larger studies that may definitively show the benefit of ultra-early decompression.

Does lower extremity fracture fixation technique influence neurologic outcomes in patients with traumatic brain injury? The EAST Brain vs. Bone multicenter trial

OBJECTIVE

This study aimed to determine whether lower extremity fracture fixation technique and timing (≤24 vs. >24 hours) impact neurologic outcomes in TBI patients.

METHODS

A prospective observational study was conducted across 30 trauma centers. Inclusion criteria were age 18 years and older, head Abbreviated Injury Scale (AIS) score of >2, and a diaphyseal femur or tibia fracture requiring external fixation (Ex-Fix), intramedullary nailing (IMN), or open reduction and internal fixation (ORIF). The analysis was conducted using analysis of variamce, Kruskal-Wallis, and multivariable regression models. Neurologic outcomes were measured by discharge Ranchos Los Amigos Revised Scale (RLAS-R).

RESULTS

Of the 520 patients enrolled, 358 underwent Ex-Fix, IMN, or ORIF as definitive management. Head AIS was similar among cohorts. The Ex-Fix group experienced more severe lower extremity injuries (AIS score, 4-5) compared with the IMN group (16% vs. 3%, p = 0.01) but not the ORIF group (16% vs. 6%, p = 0.1). Time to operative intervention varied between the cohorts with the longest time to intervention for the IMN group (median hours: Ex-Fix, 15 [8-24] vs. ORIF, 26 [12-85] vs. IMN, 31 [12-70]; p < 0.001). The discharge RLAS-R score distribution was similar across the groups. After adjusting for confounders, neither method nor timing of lower extremity fixation influenced the discharge RLAS-R. Instead, increasing age and head AIS score were associated with a lower discharge RLAS-R score (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.002-1.03 and OR, 2.37; 95% CI, 1.75-3.22), and a higher Glasgow Coma Scale motor score on admission (OR, 0.84; 95% CI, 0.73-0.97) was associated with higher RLAS-R score at discharge.

CONCLUSION

Neurologic outcomes in TBI are impacted by severity of the head injury and not the fracture fixation technique or timing. Therefore, the strategy of definitive fixation of lower extremity fractures should be dictated by patient physiology and the anatomy of the injured extremity and not by the concern for worsening neurologic outcomes in TBI patients.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level III.

International Survey of Antiseizure Medication Use in Patients with Complicated Mild Traumatic Brain Injury: A New York Neurotrauma Consortium Study

BACKGROUND

Seizures and epilepsy after traumatic brain injury (TBI) negatively affect quality of life and longevity. Antiseizure medication (ASM) prophylaxis after severe TBI is associated with improved outcomes; these medications are rarely used in mild TBI. However, a paucity of research is available to inform ASM use in complicated mild TBI (cmTBI) and no empirically based clinical care guidelines for ASM use in cmTBI exist. We aim to identify seizure prevention and management strategies used by clinicians experienced in treating patients with cmTBI to characterize standard care and inform a systematic approach to clinical decision making regarding ASM prophylaxis.

METHODS

We recruited a multidisciplinary international cohort through professional organizational listservs and social media platforms. Our questionnaire assessed factors influencing ASM prophylaxis after cmTBI at the individual, institutional, and health system-wide levels.

RESULTS

Ninety-two providers with experience managing cmTBI completed the survey. We found a striking diversity of ASM use in cmTBI, with 30% of respondents reporting no/infrequent use and 42% reporting frequent use; these tendencies did not differ by provider or institutional characteristics. Certain conditions universally increased or decreased the likelihood of ASM use and represent consensus. Based on survey results, ASMs are commonly used in patients with cmTBI who experience acute secondary seizure or select positive neuroimaging findings; we advise caution in elderly patients and those with concomitant neuropsychiatric illness.

CONCLUSIONS

This study is the first to characterize factors influencing clinical decision making in ASM prophylaxis after cmTBI based on multidisciplinary multicenter provider practices. Prospective controlled studies are necessary to inform standardized guideline development.

Intracranial extramedullary hematopoiesis in a patient with beta-thalassemia presenting with head trauma

Background:

Beta-thalassemia is an inherited hemoglobinopathy, whereby reduced or absent expression of beta-globin genes causes impaired erythropoiesis. Extramedullary hematopoiesis (EMH) occurs in 1% of all patients with beta-thalassemia major receiving regular transfusions and is exceedingly rare intracranially.

Case Description:

We report a case of a male in his 20s with beta thalassemia who presented with head trauma found to have intracranial EMH mimicking multiple extra-axial hematomas. Making the correct diagnosis was critical in avoiding prolonged neuromonitoring and unnecessary interventions.

Conclusion:

Intracranial extramedullary hematopoietic pseudotumor is an exceedingly rare entity and seldom appears in a neurosurgeon’s differential diagnosis. This case illustrates how this condition can easily mimic an acute intracranial hemorrhage in a patient with beta-thalassemia who presents with head trauma. We review the topic to further inform clinicians who may encounter this condition in their practice.

Brainstem Hemorrhage Following Lumbar Drain for Post-traumatic Hydrocephalus

Post-traumatic hydrocephalus is common after traumatic brain injury (TBI), particularly following decompressive craniectomy. Cerebrospinal fluid (CSF) removal by lumbar drain (LD) aids in the workup of post-traumatic hydrocephalus and serves as a bridge to definitive CSF diversion. Hemorrhagic complications following LD are rare but can include intracranial hemorrhage. We present a case of fatal brainstem hemorrhage following LD in a patient three months after craniectomy.

A 32-year-old male presented with severe TBI and an acute subdural hematoma. He underwent emergent decompressive craniectomy and hematoma evacuation. The next day, he required ventriculostomy for elevated intracranial pressure (ICP), which was able to be successfully removed. Three months after the injury, the patient’s neurological exam declined, and computed tomography (CT) findings were consistent with communicating hydrocephalus. An LD was placed with 15 mL of CSF and drained every two hours. Five days after LD placement, the CSF became blood-tinged, and a repeat head CT demonstrated an acute brainstem hemorrhage. The patient ultimately expired.

Given the prevalence of post-traumatic hydrocephalus and the frequent use of CSF diversion in the management of this condition, it is important for neurosurgeons to remain cognizant of the potential risk for catastrophic brainstem hemorrhage following LD in decompressive craniectomy patients.

Racial and Socioeconomic Disparities in Neurotrauma: Research Priorities in the New York Metropolitan Area through a Global Neurosurgery Paradigm

The New York Neurotrauma Consortium (NYNC) is a nascent multidisciplinary research and advocacy organization based in the New York Metropolitan Area (NYMA). It aims to advance health equity and optimize outcomes for traumatic brain and spine injury patients. Given the extensive racial, ethnic, and socioeconomic diversity of the NYMA, global health frameworks aimed at eliminating disparities in neurotrauma may provide a relevant and useful model for the informing research agendas of consortia like the NYNC. In this review, we present a comparative analysis of key health disparities in traumatic brain injury (TBI) that persist in the NYMA as well as in low- and middle-income countries (LMIC). Examples include: (a) inequitable access to quality care due to fragmentation of healthcare systems, (b) barriers to effective prehospital care for TBI, and (c) socioeconomic challenges faced by patients and their families during the subacute and chronic post-injury phases of TBI care. This review presents strategies to address each area of health disparity based on previous studies conducted in both LMIC and high-income country (HIC) settings. Increased awareness of healthcare disparities, education of healthcare professionals, effective policy advocacy for systemic changes, and fostering racial diversity of the trauma care workforce can guide the development of trauma care systems in the NYMA that are free of racial and related healthcare disparities.

The Effect of Direct Oral Anti-Coagulants on Delayed Traumatic Intracranial Hemorrhage After Mild Traumatic Brain Injury: A Systematic Review

BACKGROUND

The use of anticoagulant medications leads to a higher risk of developing traumatic intracranial hemorrhage (tICH) after a mild traumatic brain injury (mTBI). The management of anticoagulated patients can be difficult to determine when the initial head computed tomography is negative for tICH. There has been limited research on the risk of delayed tICH in patients taking direct oral anticoagulant (DOAC) medications.

OBJECTIVE

Our aim was to determine the risk of delayed tICH for patients anticoagulated with DOACs after mTBI.

METHODS

We conducted a systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and searched several medical databases to examine the risk of delayed tICH in patients on DOACs.

RESULTS

There were 1252 nonduplicate studies that were identified through an initial database search, 15 of which met our inclusion and exclusion criteria and were included in our analysis after full-text review. A total of 1375 subjects were combined among the 15 studies, with 20 instances of delayed tICH after mTBI. Nineteen of the 20 patients with a delayed tICH were discharged without any neurosurgical intervention, and 1 patient on apixaban died due to a delayed tICH.

CONCLUSIONS

This systematic review confirms that delayed tICH after mTBI in patients on DOACs is uncommon. However, large, multicenter, prospective studies are needed to confirm the true incidence of clinically significant delayed tICH after DOAC use. Due to the limited data, we recommend using shared decision-making for patients who are candidates for discharge.

Antiepileptics for Post-Traumatic Seizure Prophylaxis after Traumatic Brain Injury

Traumatic brain injury (TBI) is an important public health concern plagued by high rates of mortality and significant long-term disability in many survivors. Post-traumatic seizures (PTS) are not uncommon following TBI, both in the early (within 7 days post-injury) and late (after 7 days post-injury) period. Due to the potential of PTS to exacerbate secondary injury following TBI and the possibility of developing post-traumatic epilepsy (PTE), the medical community has explored preventative treatment strategies. Prophylactic antiepileptic drug (AED) administration has been proposed as a measure to reduce the incidence of PTS and the ultimate development of PTE in TBI patients. In this topical review, we discuss the pathophysiologic mechanisms of early and late PTS and the development of PTE following TBI, the pharmacodynamic and pharmacokinetic properties of AEDs commonly used to prevent post-traumatic seizures, and summarize the available clinical evidence for employing AEDs for seizure prophylaxis after TBI.

Variability in Outcome After Elective Cerebral Aneurysm Repair in High-Volume Academic Medical Centers

Background and Purpose—

Unruptured intracranial aneurysm repair is the most commonly performed procedure for the prevention of hemorrhagic stroke. Despite efforts to regionalize care in high-volume centers, overall results have improved little. This study aims to determine the effectiveness in improving outcomes of previous efforts to regionalize unruptured intracranial aneurysm repair to high-volume centers and to recommend future steps toward that goal.

Methods—

Using data obtained via the New York Statewide Planning and Research Cooperative System, this study included all patients admitted to any of the 10 highest volume centers in New York state between 2005 and 2010 with a principal diagnosis of unruptured intracranial aneurysm who were treated either by microsurgical or endovascular repair. Mixed-effects logistic regression was used to determine the degree to which hospital-level and patient-level variables contributed to observed variation in good outcome, defined as discharge to home, between hospitals.

Results—

Of 3499 patients treated during the study period, 2692 (76.9%) were treated at the 10 highest volume centers, with 2198 (81.6%) experiencing a good outcome. Good outcomes varied widely between centers, with 44.6% to 91.1% of clipped patients and 75.4% to 92.1% of coiled patients discharged home. Mixed-effects logistic regression revealed that procedural volume accounts for 85.8% of the between-hospital variation in outcome.

Conclusions—

There is notable interhospital heterogeneity in outcomes among even the largest volume unruptured intracranial aneurysm referral centers. Although further regionalization may be needed, mandatory participation in prospective, adjudicated registries will be necessary to reliably identify factors associated with superior outcomes.

Transnasal endoscopic approach to the pediatric craniovertebral junction and rostral cervical spine: case series and literature review

The endoscopic transnasal approach to the rostral pediatric spine and craniovertebral junction is a relatively new technique that provides an alternative to the traditional transoral approach to the anterior pediatric spine. In this case series, the authors provide 2 additional examples of patients undergoing endoscopic transnasal odontoidectomies for ventral decompression of the spinal cord. Both patients would have required transection of the palate to undergo an effective transoral operation, which can be a cause of significant morbidity. In one case, transnasal decompression was initially incomplete, and decompression was successfully achieved via a second endoscopic transnasal operation. Both cases resulted in significant neurological recovery and stable long-term spinal alignment. The transnasal approach benefits from entering into the posterior pharynx at an angle that often reduces the length of postoperative intubation and may speed a patient's return to oral intake. Higher reoperation rates are a concern for many endoscopic approaches, but there are insufficient data to conclude if this is the case for this procedure. Further experience with this technique will provide a better understanding of the indications for which it is most effective. Transcervical and transoral endoscopic approaches have also been reported and provide additional options for pediatric anterior cervical spine surgery.

A phase I clinical trial of tiopronin, a putative neuroprotective agent, in aneurysmal subarachnoid hemorrhage

BACKGROUND

The neurotoxic aldehyde 3-aminopropanal (3-AP) contributes to brain injury following cerebral ischemia. Tiopronin (N-2-mercaptopropionyl-glycine[N-2-MPG]) is a US Food and Drug Administration (FDA)-approved drug for the treatment of cystinuria and a putative neuroprotective agent that has been shown to bind and neutralize 3-AP and reduce infarct volumes.

OBJECTIVE

The objective of this trial was to establish the safety of tiopronin administration in patients with aneurysmal subarachnoid hemorrhage (aSAH) in preparation for further trials of its efficacy as a neuroprotective agent in this disease process.

METHODS

This Phase I dose-escalation trial enrolled three-patient cohorts using a conventional "3+3" study design. Tiopronin dose began at 1 g/d until aSAH Day 14. Each subsequent cohort received a dose of tiopronin based on predetermined guidelines. A maximum dose of 3 g/d was selected, because this is the maximum FDA-approved dose for long-term cystinuria treatment. Subjects were monitored for known side effects of tiopronin.

RESULTS

Nine patients were enrolled, the minimum number required based on the study design. None of these patients experienced serious side effects attributable to tiopronin, and no adverse events were noted that could not be attributed to the pathophysiology of aSAH.

CONCLUSION

The administration of 3 g/d of tiopronin following aSAH for up to 14 days appears to be safe and without the side effects associated with long-term use. Plans for a randomized, placebo-controlled Phase II trial of tiopronin for neuroprotection following aSAH are underway.

Volume-dependent effect of perihaematomal oedema on outcome for spontaneous intracerebral haemorrhages

INTRODUCTION

It is still unknown whether subsequent perihaematomal oedema (PHE) formation further increases the odds of an unfavourable outcome.

METHODS

Demographic, clinical, radiographic and outcome data were prospectively collected in a single large academic centre. A multiple logistic regression model was then developed to determine the effect of admission oedema volume on outcome.

RESULTS

133 patients were analysed in this study. While there was no significant association between relative PHE volume and discharge outcome (p=0.713), a strong relationship was observed between absolute PHE volume and discharge outcome (p=0.009). In a multivariate model incorporating known predictors of outcome, as well as other factors found to be significant in our univariate analysis, absolute PHE volume remained a significant predictor of poor outcome only in patients with intracerebral haemorrhage (ICH) volumes ≤30 cm(3) (OR 1.123, 95% CI 1.021 to 1.273, p=0.034). An increase in absolute PHE volume of 10 cm(3) in these patients was found to increase the odds of poor outcome on discharge by a factor of 3.19.

CONCLUSIONS

Our findings suggest that the effect of absolute PHE volume on functional outcome following ICH is dependent on haematoma size, with only patients with smaller haemorrhages exhibiting poorer outcome with worse PHE. Further studies are needed to define the precise role of PHE in driving outcome following ICH.

Decompressive hemicraniectomy without clot evacuation in dominant-sided intracerebral hemorrhage with ICP crisis

Object

Large intracerebral hemorrhage (ICH), compounded by perihematomal edema, can produce severe elevations of intracranial pressure (ICP). Decompressive hemicraniectomy (DHC) with or without clot evacuation has been considered a part of the armamentarium of treatment options for these patients. The authors sought to assess the preliminary utility of DHC without evacuation for ICH in patients with supratentorial, dominant-sided lesions.

Methods

From September 2009 to May 2012, patients with ICH who were admitted to the neurological ICU at Columbia University Medical Center were prospectively enrolled in that institution's ICH Outcomes Project (ICHOP). Five patients with spontaneous supratentorial dominant-sided ICH underwent DHC without clot evacuation for recalcitrant elevated ICP. Data pertaining to the patients' characteristics and outcomes of treatment were prospectively collected.

Results

The patients' median age was 43 years (range 30–55 years) and the ICH etiology was hypertension in 4 of 5 patients, and systemic lupus erythematosus vasculitis in 1 patient. On admission, the median Glasgow Coma Scale (GCS) score was 7 (range 5–9). The median ICH volume was 53 cm3 (range 28–79 cm3), and the median midline shift was 7.6 mm (range 3.0–11.3 mm). One day after surgery, the median decrease in midline shift was 2.7 mm (range 1.5–4.6 mm), and the median change in GCS score was +1 (range −3 to +5). At discharge, all patients were still alive, and the median GCS score was 10 (range 9–11), the median modified Rankin Scale (mRS) score was 5 (range 5–5), and the median NIHSS (National Institutes of Health Stroke Scale) score was 22 (range 17–27). Six months after hemorrhage, 1 patient had died, 2 were functionally dependent (mRS Score 4–5), and 2 were functionally independent (mRS Score 0–3). Outcomes for the patients treated with DHC were good compared with 1) outcomes for all patients with spontaneous supratentorial ICH admitted during the same period (n = 144) and 2) outcomes for matched patients (dominant ICH, GCS Score 5–9, ICH volume 28–79 cm3, age < 60 years) whose cases were managed nonoperatively (n = 5).

Conclusions

Decompressive hemicraniectomy without clot evacuation appears feasible in patients with large ICH and deserves further investigation, preferably in a randomized controlled setting.

Epidemiological trends in the neurological intensive care unit from 2000 to 2008

Intensive care units (ICU) specializing in the treatment of patients with neurological diseases (Neuro-ICU) have become increasingly common. However, there are few data on the longitudinal demographics of this patient population. Identifying admission trends may provide targets for improving resource utilization. We performed a retrospective analysis of admission logs for primary diagnosis, age, sex, and length of stay, for all patients admitted to the Neuro-ICU at Columbia University Medical Center (CUMC) between 2000 and 2008. From 2000 to 2008, inclusive, the total number of Neuro-ICU admissions increased by 49.9%. Overall mean patient age (54.6 ± 17.4 to 56.2 ± 18.0 years, p=0.041) and gender (55.9-50.3% female, p=0.005) changed significantly, while median length of stay (2 days) did not. When comparing the time period prior to construction of a larger Neuro-ICU (2000-2004) to that after completion (2005-2008), patient age (56.0 ± 17.6 compared to 56.9 ± 17.5 years, p=0.012) and median length of stay (1 compared to 2 days, p<0.001) both significantly increased. Construction of a newer, larger Neuro-ICU at CUMC led to a substantial increase in admissions and changes in diagnoses from 2000 to 2008. Advances in neurocritical care, neurosurgical practices, and the local and global expansion and utilization of ICU resources likely led to differences in lengths of stay.

Complement inhibition promotes endogenous neurogenesis and sustained anti-inflammatory neuroprotection following reperfused stroke

Background and Purpose

The restoration of blood-flow following cerebral ischemia incites a series of deleterious cascades that exacerbate neuronal injury. Pharmacologic inhibition of the C3a-receptor ameliorates cerebral injury by attenuating post-ischemic inflammation. Recent reports also implicate C3a in the modulation of tissue repair, suggesting that complement may influence both injury and recovery at later post-ischemic time-points.

Methods

To evaluate the effect of C3a-receptor antagonism on post-ischemic neurogenesis and neurological outcome in the subacute period of stroke, transient focal cerebral ischemia was induced in adult male C57BL/6 mice treated with multiple regimens of a C3a receptor antagonist (C3aRA).

Results

Low-dose C3aRA administration during the acute phase of stroke promotes neuroblast proliferation in the subventricular zone at 7 days. Additionally, the C3a receptor is expressed on T-lymphocytes within the ischemic territory at 7 days, and this cellular infiltrate is abrogated by C3aRA administration. Finally, C3aRA treatment confers robust histologic and functional neuroprotection at this delayed time-point.

Conclusions

Targeted complement inhibition through low-dose antagonism of the C3a receptor promotes post-ischemic neuroblast proliferation in the SVZ. Furthermore, C3aRA administration suppresses T-lymphocyte infiltration and improves delayed functional and histologic outcome following reperfused stroke. Post-ischemic complement activation may be pharmacologically manipulated to yield an effective therapy for stroke.

The Molecular Mechanisms that Promote Edema After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a devastating type of stroke with no effective therapies. Clinical advances in ICH treatment are limited by an incomplete understanding of the molecular mechanisms responsible for secondary injury and poor outcome. Increasing evidence suggests that cerebral edema is a major contributor to secondary injury and poor outcome in ICH. ICH activates specific signaling pathways that promote edema and damage neuronal tissue. By increasing our understanding of these pathways, we may be able to target them pharmaceutically to reduce edema in ICH patients. In this review, we focus on three major signaling pathways that promote edema after ICH: (1) the coagulation cascade and thrombin, (2) the inflammatory response and matrix metalloproteinases, and (3) the complement cascade and hemoglobin toxicity. We will describe the experimental evidence that confirms these pathways promote edema in ICH, discuss potential targets for new therapies, and comment on important directions for future research.

Predictors of long-term shunt-dependent hydrocephalus in patients with intracerebral hemorrhage requiring emergency cerebrospinal fluid diversion

Object

Intracerebral hemorrhage (ICH) is frequently complicated by acute hydrocephalus, necessitating emergency CSF diversion with a subset of patients, ultimately requiring long-term treatment via placement of permanent ventricular shunts. It is unclear what factors may predict the need for ventricular shunt placement in this patient population.

Methods

The authors performed a retrospective analysis of a prospective database (ICH Outcomes Project) containing patients with nontraumatic ICH admitted to the neurological ICU at Columbia University Medical Center between January 2009 and September 2011. A multiple logistic regression model was developed to identify independent predictors of shunt-dependent hydrocephalus after ICH. The following variables were included: patient age, admission Glasgow Coma Scale score, temporal horn diameter on admission CT imaging, bicaudate index, admission ICH volume and location, intraventricular hemorrhage volume, Graeb score, LeRoux score, third or fourth ventricle hemorrhage, and intracranial pressure (ICP) and ventriculitis during hospital stay.

Results

Of 210 patients prospectively enrolled in the ICH Outcomes Project, 64 required emergency CSF diversion via placement of an external ventricular drain and were included in the final cohort. Thirteen of these patients underwent permanent ventricular CSF shunting prior to discharge. In univariate analysis, only thalamic hemorrhage and elevated ICP were significantly associated with the requirement for permanent CSF diversion, with p values of 0.008 and 0.033, respectively. Each remained significant in a multiple logistic regression model in which both variables were present.

Conclusions

Of patients with ICH requiring emergency CSF diversion, those with persistently elevated ICP and thalamic location of their hemorrhage are at increased odds of developing persistent hydrocephalus, necessitating permanent ventricular shunt placement. These factors may assist in predicting which patients will require permanent CSF diversion and could ultimately lead to improvements in the management of this disorder and the outcome in patients with ICH.

Gain-of-function polymorphisms of cystathionine β-synthase and delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

Object

Cystathionine β-synthase (CBS) is an enzyme that metabolizes homocysteine to form H2S in the brain. Hydrogen sulfide functions as a vasodilator as well as a regulator of neuronal ion channels and multiple intracellular signaling pathways. Given the myriad effects of H2S, the authors hypothesized that patients possessing gain-of-function polymorphisms of the CBS gene will experience a decreased incidence of delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH).

Methods

Patients were enrolled in a prospective observational database of aSAH outcomes. DNA was extracted from buccal swabs and sequenced for 3 functional polymorphisms of the CBS gene (699C→T, 844ins68, and 1080C→T) by polymerase chain reaction. Serum homocysteine levels (μmol/L) were assayed. Multivariate analysis was used to determine the relationship between CBS genotype and occurrence of both angiographic vasospasm and DCI.

Results

There were 87 patients included in the study. None of the polymorphisms investigated were significantly associated with the incidence of angiographic vasospasm. However, after controlling for admission hypertension, patients with the gain-of-function 844 WT/ins genotypes were less likely to experience DCI relative to those with the 844 WT/WT genotype (86 patients, p = 0.050), while the decrease-in-function genotype 1080 TT was more likely to experience DCI relative to those with 1080 CC and CT genotypes (84 patients, p = 0.042). Serum homocysteine levels did not correlate with the extent of either angiographic vasospasm or DCI in this analysis.

Conclusions

Polymorphisms of the CBS gene that impart gain-of-function may be associated with a reduced risk of DCI after aSAH, independent of serum homocysteine. Signaling through H2S may mediate protection from DCI following aSAH through a mechanism that does not involve macrovascular vasodilation.

Impact of platelet transfusion on hematoma expansion in patients receiving antiplatelet agents before intracerebral hemorrhage

OBJECTIVES

Patients receiving antiplatelet medications are reported to be at increased risk for hematoma enlargement and worse clinical outcomes following intracerebral hemorrhage (ICH). While platelet transfusions are frequently administered to counteract qualitative platelet defects in the setting of ICH, conclusive evidence in support of this therapeutic strategy is lacking. In fact, platelet transfusions may be associated with adverse effects, and represent a finite resource. We sought to determine the clinical efficacy of platelet transfusion and its impact on systemic complications following ICH in a cohort of patients receiving antiplatelet medications.

METHODS

We retrospectively analysed the medical records of 66 patients admitted to our institution from June 2003 to July 2008 who suffered a primary ICH while receiving antiplatelet (acetylsalicylic acid and/or clopidogrel) therapy. The primary outcome was the rate of significant (>25% increase from admission) hematoma expansion in transfused (n=35) versus non-transfused (n=31) patients. Discharge modified-Rankin score (mRS) and the rates of systemic complications were also assessed.

RESULTS

There were no statistically significant differences in rates of hematoma expansion between cohorts, nor were there differences in demographic variables, systemic complications or discharge mRS. Subgroup analysis revealed that there was a higher rate of hematoma expansion in the clopidogrel cohort (p=0.034) than in the cohort of patients receiving aspirin alone.

DISCUSSION

This study suggests that platelet administration does not reduce the frequency of hematoma expansion in ICH patients receiving antiplatelet medications. This lack of efficacy may relate to transfusion timing, as a significant proportion of hematoma expansion occurs within 6 hours post-ictus. Additionally, the increased rates of hematoma expansion in the clopidogrel cohort may relate to its prolonged half-life. A larger, prospective study is warranted.

Epidemiology of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a form of hemorrhagic stroke that affects up to 30,000 individuals per year in the United States. The incidence of aSAH has been shown to be associated with numerous nonmodifiable (age, gender, ethnicity, family history, aneurysm location, size) and modifiable (hypertension, body mass index, tobacco and illicit drug use) risk factors. Although early repair of ruptured aneurysms and aggressive postoperative management has improved overall outcomes, it remains a devastating disease, with mortality approaching 50% and less than 60% of survivors returning to functional independence. As treatment modalities change and the percentage of minority and elderly populations increase, it is critical to maintain an up-to-date understanding of the epidemiology of SAH.

Exacerbation of perihematomal edema and sterile meningitis with intraventricular administration of tissue plasminogen activator in patients with intracerebral hemorrhage

OBJECTIVE

Intraventricular hemorrhage (IVH) is associated with a poor outcome. External ventricular drainage together with clot lysis through intrathecal tissue plasminogen activator (IT-tPA) has been proposed as a promising therapy. However, recent experimental work has implicated tissue plasminogen activator (tPA) in the pathogenesis of cerebral edema.

METHODS

We reviewed the records of all patients with IVH caused by primary supratentorial intracerebral hemorrhage who underwent external ventricular drainage without surgical evacuation between January 2001 and June 2008. Of these 30 patients, we identified 13 who received IT-tPA. The remaining 17 patients served as controls. Hemorrhage, edema volume, and IVH score were determined on admission and by follow-up computed tomographic scans for 96 hours after admission. Discharge outcome was evaluated using the modified Rankin Scale.

RESULTS

There were no significant differences between the treatment and controls in terms of age, Glasgow Coma Scale score, Graeb and LeRoux IVH scores, or intracerebral hemorrhage volume on admission. IT-tPA resulted in more rapid clearance of IVH as determined by the 96-hour decrease in both the Graeb IVH score (tPA, 3.00 +/- .55; control, 1.00 +/- 0.57; P = .05) and the LeRoux IVH score (tPA, 6.2 +/- 0.80; control, 2.25 +/- 1.32; P = .05). Patients treated with IT-tPA demonstrated significantly larger peak ratios of edema to intracerebral hemorrhage volume (1.24 +/- 0.14 vs 0.70 +/- 0.08 in controls; P = .002). Additionally, increased rates of sterile meningitis (46% vs 12%; P = .049) and a trend toward shunt dependence (38% vs 6%; P = .06) were observed in the tPA cohort. Nevertheless, no significant differences in outcome at discharge or length of hospital stay were observed between cohorts.

CONCLUSION

Although IT-tPA hastens the resolution of IVH, it may worsen perihematomal edema formation. Larger prospective studies are required to confirm these findings and to determine whether outcome is adversely affected by IT-tPA administration.

Genetic determinants of cerebral vasospasm, delayed cerebral ischemia, and outcome after aneurysmal subarachnoid hemorrhage

Despite extensive effort to elucidate the cellular and molecular bases for delayed cerebral injury after aneurysmal subarachnoid hemorrhage (aSAH), the pathophysiology of these events remains poorly understood. Recently, much work has focused on evaluating the genetic underpinnings of various diseases in an effort to delineate the contribution of specific molecular pathways as well as to uncover novel mechanisms. The majority of subarachnoid hemorrhage genetic research has focused on gene expression and linkage studies of these markers as they relate to the development of intracranial aneurysms and their subsequent rupture. Far less work has centered on the genetic determinants of cerebral vasospasm, the predisposition to delayed cerebral injury, and the determinants of ensuing functional outcome after aSAH. The suspected genes are diverse and encompass multiple functional systems including fibrinolysis, inflammation, vascular reactivity, and neuronal repair. To this end, we present a systematic review of 21 studies suggesting a genetic basis for clinical outcome after aSAH, with a special emphasis on the pathogenesis of cerebral vasospasm and delayed cerebral ischemia. In addition, we highlight potential pitfalls in the interpretation of genetic association studies, and call for uniformity of design of larger multicenter studies in the future.

Systemic Expression of Matrix Metalloproteinase-9 in Patients With Cerebral Arteriovenous Malformations

OBJECTIVE

Increased expression angiogenic factors, such as matrix metalloproteinases (MMPs), are associated with the formation of cerebral arteriovenous malformations (AVMs). The objective of this study was to determine plasma levels of MMP-9 of patients with AVMs.

METHODS

Blood samples were drawn from 15 patients with AVMs before treatment, 24 hours postembolization, 24 hours postresection, and 30 days postresection. Blood samples were also obtained from 30 healthy controls. Plasma MMP-9 concentrations were measured via enzyme-linked immunosorbent assay.

RESULTS

The mean plasma MMP-9 level in AVM patients at baseline was significantly higher than in control patients: 108.04 ± 16.11 versus 41.44 ± 2.44 ng/mL, respectively. The mean plasma MMP-9 level 1 day after embolization increased to 172.35 ± 53.76 ng/mL, which was not significantly elevated over pretreatment levels. One day after resection, plasma MMP-9 levels increased significantly over pretreatment levels to 230.97 ± 51.00 ng/mL. Mean plasma MMP-9 concentrations 30 days after resection decreased to 92.8 ± 18.7 ng/mL, which was not different from pretreatment levels but was still significantly elevated over control levels. MMP-9 levels did not correlate with patient sex, age, presentation, or AVM size.

CONCLUSION

Plasma MMP-9 levels are significantly elevated over controls at baseline, increase significantly immediately after surgery, and decrease to pretreatment levels during follow-up.

Preoperative antiepileptic drug administration and the incidence of postoperative seizures following bur hole-treated chronic subdural hematoma

OBJECT

Despite the prevalence of chronic subdural hematoma (CSDHs) in the rapidly growing elderly population, several aspects of disease management remain unclear. In particular, there is still conflicting evidence regarding the efficacy of antiepileptic drug (AED) prophylaxis in patients with CSDH who undergo bur hole drainage. The authors endeavored to evaluate the efficacy of AED prophylaxis in reducing the incidence of seizures and improving outcome in this patient population.

METHODS

A single surgeon's clinical database (E.S.C.) was analyzed for cases involving bur hole drainage for CSDH. Cases involving nonhemorrhagic subdural effusions as well as acute subdural hemorrhages evacuated by craniotomy were excluded from this study. Patient medical records were evaluated for relevant demographic data, medical history, imaging characteristics, clinical details of the treatment, hospital stay, and discharge summaries.

RESULTS

The authors included 88 patients with bur hole-treated CSDH. Eleven patients (12.5%) suffered at least 1 seizure between hemorrhage onset and discharge from their treatment hospital admission. Seizures were more frequent in women than men (p = 0.030) and least frequent in patients with right-sided lesions (p = 0.030). In a multiple logistic regression model, preoperative initiation of AED prophylaxis was the only significant predictor of the lower incidence of postoperative seizures (OR 0.10, p = 0.013). However, preoperative initiation of AED prophylaxis did not significantly affect outcome at discharge.

CONCLUSIONS

The finding in this study demonstrates that preoperative AED prophylaxis likely reduces the incidence of postoperative seizures in patients with CSDH treated with bur hole drainage. A future prospective randomized study is necessary to evaluate the effect of seizure reduction on clinical outcome.

Clinical features, surgical treatment, and long-term outcome in adult patients with moyamoya disease. Clinical article

OBJECT

The object of this study was to report the clinical features, surgical treatment, and long-term outcomes in adults with moyamoya phenomenon treated at a single institution in the US.

METHODS

Forty-three adult patients with moyamoya disease (mean age 40 +/- 11 years [SD], range 18-69 years) were treated with encephaloduroarteriosynangiosis (EDAS). Neurologists examined patients pre- and postoperatively. Follow-up was obtained in person or by structured telephone interview (median 41 months, range 4-126 months). The following outcomes were collected: transient ischemic attack (TIA), infarction, graft collateralization, change in cerebral perfusion, and functional level according to the modified Rankin scale (mRS). Kaplan-Meier estimates of infarction risk were calculated for comparison of surgically treated and contralateral hemispheres.

RESULTS

The majority of patients were women (65%), were Caucasian (65%), presented with ischemic symptoms (98%), and had bilateral disease (86%). Nineteen patients underwent unilateral and 24 patients bilateral EDAS (67 treated hemispheres). Collateral vessels developed in 50 (98%) of 52 hemispheres for which imaging was available and there was evidence of increased perfusion on SPECT scans in 41 (82%) of the 50 hemispheres evaluated. Periprocedural infarction (< 48 hours) occurred in 3% of the hemispheres treated. In the follow-up period patients experienced 10 TIAs, 6 infarctions, and 1 intracranial hemorrhage. Although the hemisphere selected for surgery was based upon patients' symptoms and severity of pathology, the 5-year infarction-free survival rate was 94% in the surgically treated hemispheres versus < 36% in the untreated hemispheres (p = 0.007). After controlling for age and sex, infarction was 89% less likely to occur in the surgically treated hemispheres than in the contralateral hemispheres (hazard ratio 0.11, 95% CI 0.02-0.56). Thirty-eight (88%) of 43 patients had preserved or improved mRS scores, relative to baseline status.

CONCLUSIONS

In this mixed-race population of North American patients, indirect bypass promoted adequate pial collateral development and increased perfusion in the majority of adult patients with moyamoya disease. Patients had low rates of postoperative TIAs, infarction, and hemorrhage, and the majority of patients had preserved or improved functional status.

The complement cascade as a therapeutic target in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is the second most common and deadliest form of stroke. Currently, no pharmacologic treatment strategies exist for this devastating disease. Following the initial mechanical injury suffered at hemorrhage onset, secondary brain injury proceeds through both direct cellular injury and inflammatory cascades, which trigger infiltration of granulocytes and monocytes, activation of microglia, and disruption of the blood-brain barrier with resulting cerebral edema. The complement cascade has been shown to play a central role in the pathogenesis of secondary injury following ICH, although the specific mechanisms responsible for the proximal activation of complement remain incompletely understood. Cerebral injury following cleavage of complement component 3 (C3) proceeds through parallel but interrelated pathways of anaphylatoxin-mediated inflammation and direct toxicity secondary to membrane attack complex-driven erythrocyte lysis. Complement activation also likely plays an important physiologic role in recovery following ICH. As such, a detailed understanding of the variation in functional effects of complement activation over time is critical to exploiting this target as an exciting translational strategy for intracerebral hemorrhage.

Renal dysfunction as an independent predictor of outcome after aneurysmal subarachnoid hemorrhage: a single-center cohort study

BACKGROUND AND PURPOSE

Acute kidney injury occurs in 1% to 25% of critically ill patients with small increases in creatinine adversely affecting outcome. We sought to determine the burden of acute kidney injury in patients with aneurysmal subarachnoid hemorrhage and whether this dysfunction affects outcome.

METHODS

Between 1996 and 2008, 787 consecutive patients with aneurysmal subarachnoid hemorrhage were enrolled in our prospective database. Demographics, serum creatinine levels, and discharge modified Rankin scores were recorded, and changes in creatinine clearance were calculated. A multiple logistic regression was performed using known predictors for poor outcome after aneurysmal subarachnoid hemorrhage in addition to burden of contrast-enhanced imaging and change in creatinine clearance.

RESULTS

One hundred seventy-nine (23.1%) patients were at risk for renal failure during their hospitalization. In a multivariate model, those patients who developed risk for renal failure were twice as likely to have a poor 3-month outcome (OR, 2.01; P=0.021). Survival curves comparing those not at risk, those at risk (increasing severity classes Risk, Injury, and Failure, and the 2 outcome classes Loss and End-Stage Kidney Disease [RIFLE] R), and those with renal injury or failure (RIFLE I and F) demonstrated that risk of death increases significantly as one progresses through the RIFLE classes (log rank, P<0.0001).

CONCLUSIONS

In a large, consecutive series of prospectively enrolled patients with aneurysmal subarachnoid hemorrhage, we demonstrate, using the newly defined RIFLE classification for risk of renal failure, that even seemingly insignificant decreases in creatinine clearance are associated with significantly worse 3-month outcomes. This study highlights the importance of close surveillance of renal function and stresses the value of renal hygiene in the aneurysmal subarachnoid hemorrhage population.

Impact of a protocol for acute antifibrinolytic therapy on aneurysm rebleeding after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

epsilon-Aminocaproic acid (EACA) is an antifibrinolytic agent used to prevent rebleeding in aneurysmal subarachnoid hemorrhage. Although studies have found that a decrease in rebleeding with long-term antifibrinolytic therapy is offset by an increase in ischemic deficits, more recent studies have indicated that early, short-term therapy may be beneficial.

METHODS

We instituted a protocol for acute EACA administration starting at diagnosis and continued for a maximum duration of 72 hours after subarachnoid hemorrhage onset. We compared 73 patients treated with EACA with 175 non-EACA-treated patients. We sought to identify differences in the occurrence of rebleeding, side effects, and outcome.

RESULTS

Baseline characteristics were similar in the 2 groups. There was a significant decrease in rebleeding in EACA-treated patients (2.7%) versus non-EACA patients (11.4%). There was no difference in ischemic complications between cohorts. There was a significant 8-fold increase in deep venous thrombosis in the EACA group but no increase in pulmonary embolism. There was a nonsignificant 76% reduction in mortality attributable to rebleeding, a 13.3% increase in favorable outcome in good-grade EACA-treated patients, and a 6.8% increase in poor-grade patients.

CONCLUSIONS

When used acutely, short-term EACA treatment resulted in decreased rebleeding without an increase in serious side effects in our selected group of patients. Randomized placebo-controlled trials are needed to determine whether acute antifibrinolytic therapy should be accepted as the standard of care in all patients.

Plasma levels of vascular endothelial growth factor after treatment for cerebral arteriovenous malformations

BACKGROUND AND PURPOSE

The role of abnormal angiogenesis in the formation and progression of cerebral arteriovenous malformations (AVMs) is unclear. Previous studies have demonstrated increased local expression of vascular endothelial growth factor (VEGF) in AVM tissue and increased circulating levels of VEGF in AVM patients. We sought to further investigate the role of VEGF in AVM pathophysiology by examining changes in plasma VEGF levels in patients undergoing treatment for AVMs.

METHODS

Three serial blood samples were obtained from 13 AVM patients undergoing treatment: (1) before any treatment, (2) 24 hours postresection, and (3) 30 days postresection. Plasma VEGF concentrations were measured via commercially available enzyme-linked immunosorbent assay (ELISA). For controls, blood samples were obtained from 29 lumbar laminectomy patients.

RESULTS

The mean plasma VEGF level in AVM patients at baseline was 36.08+/-13.02 pg/mL, significantly lower than that of the control group (80.52+/-14.02 pg/mL, P=0.028). Twenty-four hours postresection, plasma VEGF levels dropped to 20.09+/-4.54 pg/mL, then increased to 66.81+/-26.45 pg/mL 30 days later (P=0.048). The mean plasma VEGF concentration 30 days after resection was no longer significantly different from the control group (P=0.33).

CONCLUSIONS

Plasma VEGF levels in 13 AVM patients were unexpectedly lower than controls, dropped early after AVM resection, then significantly increased 30 days later. These results support the key role of abnormal angiogenesis in AVM pathophysiology and suggest that a disruption in systemic VEGF expression may contribute to the natural history of these lesions.

Early plasma complement C3a levels correlate with functional outcome after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Studies have documented an inflammatory response in the circulating plasma and cerebrospinal fluid of patients with aneurysmal subarachnoid hemorrhage (aSAH). In particular, early upregulation of several complement proteins, including C3a, C4a, and C5b-9, has been demonstrated after the initial hemorrhagic insult. The inflammatory actions of the complement cascade are largely mediated through the anaphylatoxins, C3a and C5a. Recent investigations have established a critical role for C3a in the pathogenesis of cerebral ischemia. We attempt to confirm that plasma C3a and C5a values are elevated in patients with aSAH and to determine whether or not these levels are reliable independent predictors of functional outcome irrespective of clinical presentation.

METHODS

Fifty-two patients with aSAH were prospectively enrolled and stratified according to admission Hunt and Hess grade, demographic variables, and functional status at the time of discharge (modified Rankin Scale score). Plasma C3a and C5a levels were determined at early and late time points after aSAH through enzyme-linked immunosorbent assay.

RESULTS

After aSAH, early C3a and C5a values were increased compared with levels in non-SAH control patients (P < 0.001). Univariate analysis demonstrated that elevations in early C3a (P = 0.010) and C5a (P = 0.041) levels and poor admission Hunt and Hess grade (P = 0.015) correlated significantly with unfavorable outcome. In our multivariate model, only early C3a levels retained a strong correlation with outcome when modeled with Hunt and Hess grade (P = 0.009).

CONCLUSION

These results demonstrate an association between early complement C3a levels and outcome after aSAH that seems to be independent of the initial hemorrhage. The findings suggest that inflammatory processes involving C3a may contribute to delayed morbidity and mortality after aneurysmal rupture.

Spatio-temporal and species-specific variation in PBDE levels/patterns in British Columbia's coastal waters

Congener-specific levels of PBDEs were measured in the livers and some muscle tissues of Dungeness crab (Cancer magister), English sole (Pleuronectes vetulus) and spiny dogfish (Squalus acanthias). Highest concentrations (1,200-560 ng/g lipid) were found in crab collected near heavily urbanized areas (pop. approximately 0.3-1.8 million), followed by moderate levels at pulp/paper mills sites ( approximately 150 ng/g), and lowest levels occurred in areas that were somewhat removed from industrial/populated areas (< 24 ng/g). Temporal increases in total PBDEs and particularly in BDE-47 for Dungeness crab collected near pulp and paper and urbanized areas between 1994 and 2000 were observed. These correspond to Canadian and worldwide trends seen for PBDEs in biota. English sole and dogfish showed a pattern similar to that of the Columbia River whitefish samples, which corresponded closely to the patterns in the "penta" commercial mixture. Conversely, Dungeness crab were enriched in lower chlorinated PBDEs, particularly BDE-47 and BDE-49, compared to the fish and shark species from BC.