Reducing implicit bias in the neurosurgery application and interview process: a single-institution experience.

OBJECTIVE: The neurosurgical match is a challenging process for applicants and programs alike. Programs must narrow a wide field of applicants to interview and then determine how to rank them after limited interaction. To streamline this, programs commonly screen applicants using United States Medical Licensing Examination (USMLE) Step scores. However, this approach removes nuance from a consequential decision and exacerbates existing biases. The primary objective of this study was to demonstrate the feasibility of effecting minor modifications to the residency application process, as the authors have done at their institution, specifically by reducing the prominence of USMLE board scores and Alpha Omega Alpha (AΩA) status, both of which have been identified as bearing racial biases. METHODS: At the authors' institution, residents and attendings holistically reviewed applications with intentional redundancy so that every file was reviewed by two individuals. Reviewers were blinded to applicants' photographs and test scores. On interview day, the applicant was evaluated for their strength in three domains: knowledge, commitment to neurosurgery, and integrity. For rank discussions, applicants were reviewed in the order of their domain scores, and USMLE scores were unblinded. A regression analysis of the authors' rank list was made by regressing the rank list by AΩA status, Step 1 score, Step 2 score, subinternship, and total interview score. RESULTS: No variables had a significant effect on the rank list except total interview score, for which a single-point increase corresponded to a 15-position increase in rank list when holding all other variables constant (p < 0.05). CONCLUSIONS: The goal of this holistic review and domain-based interview process is to mitigate bias by shifting the focus to selected core qualities in lieu of traditional metrics. Since implementation, the authors' final rank lists have closely reflected the total interview score but were not significantly affected by board scores or AΩA status. This system allows for the removal of known sources of bias early in the process, with the aim of reducing potential downstream effects and ultimately promoting a final list that is more reflective of stated values.

Turnover Time Between Elective Operative Cases: Does the Witching Hour Exist for the Operating Room?

BACKGROUND: Efficient resource management in the operating room (OR) contributes significantly to healthcare expenditure and revenue generation for health systems. We aim to assess the influence that surgeon, anesthesiology, and nursing team assignments and time of day have on turnover time (TOT) in the OR. METHODS: We performed a retrospective review of elective cases at a single academic hospital that were completed between Monday and Friday between the hours of 0700 and 2359 from July 1, 2017, through March 31, 2018. Emergent cases and unplanned, add-on cases were excluded. Data regarding patient characteristics, OR teams, TOT, and procedure start and end times were collected and analyzed. RESULTS: A total of 2174 total cases across 13 different specialties were included in our study. A multivariate regression of relevant variables affecting TOT was performed. Consecutive specialty (p < 0.0001), consecutive surgeon (p < 0.0001), anesthesiologist (p < 0.0001), and prior case ending before 1400 (p < 0.0001) were independent predictors of lower TOT. A receiver operating characteristic analysis demonstrated an area under the curve of 0.848 and a cutoff of 1400 having the highest sensitivity and specificity for TOT difference. CONCLUSIONS: TOT can be significantly affected by the time of the day the procedure is performed. Staffing availability during late procedures and the differences in how OR team staff are scheduled may affect OR efficiency. Additional studies may be needed to determine the long-term implications of changes implemented to decrease organizational operational costs related to the OR.

Biomarkers related to hypertrophy of the ligamentum flavum: a systematic review of the literature.

OBJECTIVE: Spinal stenosis is one of the most common spinal disorders in the elderly. Hypertrophy of the ligamentum flavum (HLF) can contribute to spinal stenosis. The current literature suggests that various biomarkers may play important roles in the pathogenesis of HLF. However, the connection between these biomarkers and the development of HLF is still not well understood. This systematic review aims to explore the current literature on biomarkers related to the development of HLF. METHODS: A literature search was conducted using PubMed, Embase, Web of Science, and Cochrane Library. The search strategy looked for the titles, abstracts, and keywords of studies that contained a combination of the following phrases: "ligamentum flavum OR yellow ligament," "biomarkers," and "hypertrophy." Recorded data included study design, demographic characteristics (number of patients of each gender and mean age), study period, country where the study was conducted, biomarkers, and diagnostic modalities used. Risk of bias was assessed using the Newcastle-Ottawa Scale for case-control studies. RESULTS: The authors identified 39 studies. After screening, 26 full-text original articles assessing one or more biomarkers related to HLF were included. The included studies were conducted over a 22-year period. The most popular biomarkers studied, in order of frequency reported, were collagen types I and III (n = 10), transforming growth factor ß (TGF-ß) (n = 8), and interleukin (IL)-6 (n = 6). The authors found that mechanical stretching forces, tissue inhibitor of metalloproteinases 2 (TIMP-2) induction, and TGF-ß were associated with increased amounts of collagen I and III. IL-6 expression was increased by microRNA-21, as well as by leptin, through the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. CONCLUSIONS: Biomarkers such as TGF-ß, IL-6, and collagen I and III have been consistently correlated with the development of HLF. However, the pathogenesis of HLF remains unclear due to the heterogeneity of the studies, patient populations, and research at the molecular level. Further studies are necessary to better characterize the pathogenesis of HLF and provide a more comprehensive understanding of how these biomarkers may aid in the diagnosis and treatment of HLF.

Concerns, Perceptions, and Career Considerations of Female Medical Students Interested in Neurosurgery: A Qualitative Case Study.

BACKGROUND: Neurosurgery exhibits notably lower representation of Black, Hispanic, and female surgeons compared to various other medical and surgical specialties. Existing research focuses on medical students' views on surgeons, factors influencing female medical students' preferences in surgical fields, and the perceived interests and concerns of students contemplating a career in neurosurgery. However, there is a significant gap in understanding the unique concerns and perspectives of female medical students interested in neurosurgery. METHODS: Semi-structured interviews with female medical students were recruited from medical schools in the DC area. Interview questions were based on Lent and Brown's Social Cognitive Career Theory. Transcripts were analyzed thematically into codes. RESULTS: In total, 8 female medical students from our institution participated. We identified three major themes that influenced medical students decision making: sense of belonging (diversity, mentorship, passionate), self-efficacy (ambitious/"gunner", intense/competitive), and outcome expectations (innovation/research, immediate impact, procedural/surgical aspect, salary, work-life balance). CONCLUSION: Female medical students face distinct challenges and factors to consider when choosing a career in neurological surgery. The biggest concern for female students was a sense of belonging. It is imperative to enhance the diversity within the neurosurgical specialty and boost the representation of female neurosurgeons. Early interventions designed to tackle and alleviate their specific concerns are pivotal in achieving this goal.

Utility of prolonged prophylactic systemic antibiotics for wound drains in posterior spine surgery: a systematic review and meta-analysis.

OBJECTIVE: Closed suction drains, often used after posterior spinal surgery, pose a potential risk of infection. To combat this risk, many surgeons opt for a prolonged prophylactic antibiotic regimen. Since 2015, several studies have shown that prolonged prophylactic systemic antibiotics (PPSA) for drains provides no additional benefit in reducing surgical site infection (SSI) rates. However, most of these studies lacked sufficient power to make reliable conclusions. To date, there has been no meta-analysis conducted to further investigate this issue. The aim of this study was to investigate whether a regimen of PPSA reduces the incidence of deep SSIs in adult patients with closed suction drains following posterior spinal surgeries. METHODS: The protocol of the current systematic review was registered with PROSPERO. A systematic review of the literature in PubMed (Medline), Europe PMC, Embase, and Cochrane Review databases was conducted for all relevant literature with the keywords "spine," "antibiotics," "surgical site infection," "prophylaxis," and "drain." Retrospective and prospective studies investigating the effectiveness of PPSA in patients 18 years or older who underwent posterior cervical or thoracolumbar surgery and had postoperative wound drains were included. The primary outcome was the odds ratio for deep SSI based on the intervention (PPSA vs non-PPSA). The secondary outcomes were the rates of superficial and overall SSIs. RESULTS: From a total of 2558 titles identified from the search, 7 studies were chosen for final analysis. Three were randomized controlled trials (RCTs), and 4 were retrospective reviews. A total of 2446 patients were analyzed; 1149 received a PPSA regimen and 1297 received a non-PPSA regimen. Deep SSIs occurred in 45 patients (3.9%) and 46 patients (3.5%) in the PPSA and non-PPSA groups, respectively. The odds ratio for deep SSIs in the PPSA group compared with the non-PPSA group was 1.10 (95% CI 0.69-1.74), which was not statistically significant. Additionally, there were no differences in the rates of superficial and overall SSIs. There was a trend toward increased infections with multidrug-resistant bacteria (Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus) in the PPSA group; however, it was not possible to perform a durable statistical analysis because of the small number of reported organisms in the selected publications. CONCLUSIONS: This meta-analysis demonstrates that there is no reduction in rate of deep, superficial, and overall SSIs with prolonged prophylactic antibiotics after posterior spinal surgery involving the use of closed suction drains.

Decompressive hemicraniectomy and cranioplasty using subcutaneously preserved autologous bone flaps versus synthetic implants: perioperative outcomes and cost analysis.

OBJECTIVE: It has not been well-elucidated whether there are advantages to preserving bone flaps in abdominal subcutaneous (SQ) tissue after decompressive hemicraniectomy (DHC), compared to discarding bone flaps. The authors aimed to compare perioperative outcomes and costs for patients undergoing autologous cranioplasty (AC) after DHC with the bone flap preserved in abdominal SQ tissue, and for patients undergoing synthetic cranioplasty (SC). METHODS: A retrospective review was performed of all patients undergoing DHC procedures between January 2017 and July 2021 at two tertiary care institutions. Patients were divided into two groups: those with flaps preserved in SQ tissue (SQ group), and those with the flap discarded (discarded group). Additional analysis was performed between patients undergoing AC versus SC. Primary end points included postoperative and surgical site complications. Secondary endpoints included operative costs, length of stay, and blood loss. RESULTS: A total of 248 patients who underwent DHC were included in the study, with 155 patients (62.5%) in the SQ group and 93 (37.5%) in the discarded group. Patients in the discarded group were more likely to have a diagnosis of severe TBI (57.0%), while the most prevalent diagnosis in the SQ group was malignant stroke (35.5%, p < 0.05). There were 8 (5.2%) abdominal surgical site infections and 9 (5.8%) abdominal hematomas. The AC group had a significantly higher reoperation rate (23.2% vs 12.9%, p = 0.046), with 11% attributable to abdominal reoperations. The average cost of a reoperation for an abdominal complication was $40,408.75 ± $2273. When comparing the AC group to the SC group after cranioplasty, there were no significant differences in complications or surgical site infections. There were 6 cases of significant bone resorption requiring cement supplementation or discarding of the bone flap. Increased mean operative charges were found for the SC group compared to the AC group ($72,362 vs $59,726, p < 0.001). CONCLUSIONS: Autologous bone flaps may offer a cost-effective option compared to synthetic flaps. However, when preserved in abdominal SQ tissue, they pose the risk of resorption over time as well as abdominal surgical site complications with increased reoperation rates. Further studies and methodologies such as cryopreservation of the bone flap may be beneficial to reduce costs and eliminate complications associated with abdominal SQ storage.

Inadvertent intrathecal administration of daunomycin resulting in fatality: Case report and therapeutic considerations.

BACKGROUND: Daunomycin is a chemotherapeutic agent of the anthracycline family that is administered intravenously, most commonly in combination therapy. The authors report the first known adult case of inadvertently administered daunomycin directly into the human central nervous system and the neurologic manifestations and therapeutic interventions that followed. CLINICAL DESCRIPTION: A 53-year-old male presenting to the hospital for his second cycle of consolidation therapy for acute promyelocytic leukemia t(15;17) was accidentally administered 93 mg of intrathecal (IT) daunomycin. Within several hours of injection, the patient subsequently developed bilateral lower extremity pain, ascending paresthesias, headache, and left cranial nerve (CN) III palsy. Immediately following these neurologic sequalae, a subarachnoid lumbar drain was placed at the L4-5 interspace for the initial irrigation and drainage of cerebrospinal fluid (CSF). By hospital day 2, the patient's mental status significantly declined requiring an external ventricular drain (EVD) for hydrocephalus. Despite therapeutic interventions, the patient developed an ascending radiculomyeloencephalopathy with deterioration in clinical status. Eighteen days after the inadvertent injection of IT daunomycin, the patient became comatose and lost all cranial nerve function. CONCLUSIONS: Accidental IT injection of daunomycin is a neurosurgical emergency and warrants prompt intervention. Symptoms can mimic other medical conditions, making it imperative an accurate diagnosis is made so that appropriate therapies are implemented. At this time, therapies include rapid removal of the chemotherapeutic agent from the IT compartment by aspiration and irrigation; however, it is unclear if neuroprotective agents may provide added benefit.

Effect of Incisional Negative Pressure Wound Therapy vs Standard Wound Dressing on the Development of Surgical Site Infection after Spinal Surgery: A Prospective Observational Study.

BACKGROUND: Use of a closed-incisional negative pressure therapy (ci-NPT) dressing is an emerging strategy to reduce surgical site infections (SSIs) in spine surgery that lacks robust data. OBJECTIVE: To determine the impact of a ci-NPT, as compared with a standard dressing, on the development of SSIs after spine surgery. METHODS: This was a prospective observational study over a 2-yr period. Indications for surgery included degenerative disease, deformity, malignancy, and trauma. Exclusion criteria included anterior and lateral approaches to the spine, intraoperative durotomy, or use of minimally invasive techniques. SSIs up to 60 d following surgery were recorded. RESULTS: A total of 274 patients were included. SSI rate was significantly lower with ci-NPT dressing (n = 118) as compared with the standard dressing (n = 156) (3.4 vs 10.9%, P = .02). There was no statistical difference in infection rate for decompression alone procedures (4.2 vs 9.1%, P = .63), but there was a statistically significant reduction with the use of a negative-pressure dressing in cases that required instrumentation (3.2 vs 11.4%, P = .03). Patients at higher risk (instrumentation, deformity, and malignancy) had less SSIs with the use of ci-NPT, although this did not reach statistical significance. There were no complications in either group. CONCLUSION: SSI rates were significantly reduced with a ci-NPT dressing vs a standard dressing in patients who underwent spinal surgery. The higher cost of a ci-NPT dressing might be justified with instrumented cases, as well as with certain high-risk patient populations undergoing spine surgery, given the serious consequences of an infection.

Comparison of Clinical and Radiographic Outcomes After Standalone Versus Cage and Plate Constructs for Anterior Cervical Discectomy and Fusion.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) has conventionally been performed using an allograft cage with a plate-and-screw construct. Recently, standalone cages have gained popularity due to theorized decreases in operative time and postoperative dysphagia. Few studies have compared these outcomes. Here, we directly compare the outcomes of plated versus standalone ACDF constructs. METHODS: A single-center retrospective review of patients undergoing ACDF after June 2011 with at least 6 months of follow up was conducted. Clinical outcomes were analyzed and compared between standalone and plated constructs. Multivariate regression analysis of the primary outcome, need for revision surgery, as well as several secondary outcomes, procedure duration, estimated blood loss (EBL), length of hospital stay, disposition, and incidence of dysphagia, hoarseness, or surgical site infection, was completed. RESULTS: A total of 321 patients underwent ACDF and met inclusion-exclusion criteria, with mean follow-up duration of 20 months. Forty-six (14.3%) patients received standalone constructs, while 275 (85.7%) received plated constructs. Fourteen (4.4%) total revisions were necessary, 4 in the standalone group and 10 in the plated group, yielding revision rates of 8.7% and 3.6%, respectively (P = .125). Mean EBL was 98 mL in the standalone group and 63 mL in the plated group (P = .001). Mean procedure duration was 147 minutes in the standalone group and 151 minutes in the plated group (P = .800). Mean hospital stay was 3.6 days in the standalone group and 2.5 days in the plated group (P = .270). There was no significant difference in incidence of dysphagia (P = .700) or hoarseness (P = .700). CONCLUSIONS: Standalone ACDF demonstrates higher, but not statistically significant, revision rates than plate-and-screw constructs, without the hypothesized decreased incidence of dysphagia or hoarseness and without decreased procedure duration or EBL. Surgeons may consider limiting use of these constructs to cases of adjacent segment disease. Larger studies with longer follow up are necessary to make more definitive conclusions. LEVEL OF EVIDENCE: 4. CLINICAL RELEVANCE: This study will help spine surgeons decide between using standalone or cage-and-plate constructs for ACDF.

Left iliac artery injury during anterior lumbar spine surgery diagnosed by intraoperative neurophysiological monitoring.

Serious vascular injury is a rare, but potentially devastating complication during anterior lumbar spinal surgery. The authors describe the first reported case where vascular injury was detected by multimodality neurophysiological monitoring during an L3-S1 anterior lumbar interbody fusion. The case demonstrates the need for multi-modality monitoring and the combined use of somatosensory-evoked potentials and motor-evoked potentials.

Human motor evoked potential responses following spinal cord transection: an in vivo study.

Motor evoked potential (MEP) monitoring has been used increasingly in conjunction with somatosensory evoked potential monitoring to monitor neurological changes during complex spinal operations. No published report has demonstrated the effects of segmental spinal cord transection on MEP monitoring. The authors describe the case of an 11-year-old girl with lumbar myelomeningocele and worsening thoracolumbar scoliosis who underwent a T11-L5 fusion and spinal transection to prevent tethering. Intraoperative MEP and somatosensory evoked potential monitoring were performed, and the spinal cord was transected in 4 quadrants. The MEPs were lost unilaterally as each anterior quadrant was sectioned. This is the first reported case that demonstrates the link between spinal cord transection and MEP signaling characteristics. Furthermore, it demonstrates the relatively minor input of the ipsilateral ventral corticospinal tract in MEP physiology at the thoracolumbar junction. Finally, this study further supports the use of MEPs as a specific intraoperative neuromonitoring tool.

Arteriovenous Malformations Treated With Frameless Robotic Radiosurgery Using Non-Invasive Angiography: Long-Term Outcomes of a Single Center Pilot Study.

OBJECTIVE: CT-guided, frameless robotic radiosurgery is a novel radiotherapy technique for the treatment of intracranial arteriovenous malformations (AVMs) that serves as an alternative to traditional catheter-angiography targeted, frame-based methods. METHODS: Patients diagnosed with AVMs who completed single fraction frameless robotic radiosurgery at Medstar Georgetown University Hospital between July 20, 2006 - March 11, 2013 were included in the present study. All patients received pre-treatment planning with CT angiogram (CTA) and MRI, and were treated using the CyberKnife radiosurgery platform. Patients were followed for at least four years or until radiographic obliteration of the AVM was observed. RESULTS: Twenty patients were included in the present study. The majority of patients were diagnosed with Spetzler Martin Grade II (35%) or III (35%) AVMs. The AVM median nidus diameter and nidal volume was 1.8 cm and 4.38 cc, respectively. Median stereotactic radiosurgery dose was 1,800 cGy. After a median follow-up of 42 months, the majority of patients (81.3%) had complete obliteration of their AVM. All patients who were treated to a total dose of 1800 cGy demonstrated complete obliteration. One patient treated at a dose of 2,200 cGy developed temporary treatment-related toxicity, and one patient developed post-treatment hemorrhage. CONCLUSIONS: Frameless robotic radiosurgery with non-invasive CTA and MRI radiography appears to be a safe and effective radiation modality and serves as a novel alternative to traditional invasive catheter-angiography, frame-based methods for the treatment of intracranial AVMs. Adequate obliteration can be achieved utilizing 1,800 cGy in a single fraction, and minimizes treatment-related side effects.

Crossing the Cervicothoracic Junction During Posterior Cervical Decompression and Fusion: Is It Necessary?

BACKGROUND: Posterior cervical fusion (PCF) is performed to treat cervical myelopathy, radiculopathy, and/or deformity. Constructs ending at the cervicothoracic junction (CTJ) may lead to higher rates of adjacent segment disease, and much debate exists regarding crossing the CTJ due to paucity of data in the literature. OBJECTIVE: To determine whether extension of PCF constructs across the CTJ decreases incidence of adjacent segment disease and need for revision surgery. METHODS: A single-center retrospective case series of patients undergoing multilevel PCFs since 2011 with at least 6-mo follow-up was conducted. Outcomes were analyzed and compared based on caudal extent of instrumentation via multivariate regression. RESULTS: A total of 149 patients underwent PCF, with a mean follow-up of 18.9 mo. A total of 15 (10.1%) revisions were performed, 7 (4.7%) of which were related to the construct. Five (8.3%) revisions were performed for constructs ending at C6, 1 (5.3%) at C7, 1 (2.6%) at T1, and none (0%) at T2 (P = .035). Mean procedure duration was 215 min at C6, 214 min at C7, 239 min at T1, and 343 min at T2 (P = .001). Mean estimated blood loss was 224 mL at C6, 178 mL at C7, 308 mL at T1, and 575 mL at T2 (P = .001). There was no difference in length of stay, disposition, surgical site infection, or radiographic parameters. CONCLUSION: Extension of PCFs across the CTJ leads to lower early revision rates, but also to increased procedure duration and estimated blood loss. As such, decisions regarding caudal extent of instrumentation must weigh the risk of pseudarthrosis against that of longer procedures with higher blood loss.

Neuronal RAGE expression modulates severity of injury following transient focal cerebral ischemia.

Inflammation has a significant role in the neurological injury that follows stroke. The receptor for advanced-glycation end products (RAGE) is a multiligand member of the immunoglobulin superfamily that has been implicated in multiple neuronal and inflammatory stress processes. To directly test the role of neuronal RAGE in stroke, we employed two cohorts of transgenic mice, one over-expressing full-length functional human RAGE in neurons, and the other a human RAGE transgene in which deletion of the cytoplasmic domain of the receptor in neurons suppresses signal transduction stimulated by ligands (referred to as dominant negative or DN-RAGE). We found a statistically significant increase in stroke volume in the RAGE over-expressing cohort compared to normal controls, and a trend towards decreased stroke volume in the DN RAGE cohort. These results indicate that RAGE signaling directly contributes to pathology in cerebral ischemia.

Complement component C3 mediates inflammatory injury following focal cerebral ischemia.

The complement cascade has been implicated in ischemia/reperfusion injury, and recent studies have shown that complement inhibition is a promising treatment option for acute stroke. The development of clinically useful therapies has been hindered, however, by insufficient understanding of which complement subcomponents contribute to post-ischemic injury. To address this issue, we subjected mice deficient in selected complement proteins (C1q, C3, C5) to transient focal cerebral ischemia. Of the strains investigated, only C3-/- mice were protected, as demonstrated by 34% reductions in both infarct volume (P<0.01) and neurological deficit score (P<0.05). C3-deficient mice also manifested decreased granulocyte infiltration (P<0.02) and reduced oxidative stress (P<0.05). Finally, administration of a C3a-receptor antagonist resulted in commensurate neurological improvement and stroke volume reduction (P<0.05). Together, these results establish C3 activation as the key constituent in complement-related inflammatory tissue injury following stroke and suggest a C3a anaphylatoxin-mediated mechanism.

Creating a Culture of Collaboration: A Brief History of Academic Neurosurgery in Washington, DC.

Clinical neurosurgery has been practiced in the US capital for just over 100 years. As former residents and fellows of Drs. Harvey Cushing and Walter Dandy moved to the region, hospitals at Georgetown and George Washington Universities became early adopters of this new surgical discipline. Later academic neurosurgery programs were established at the National Institutes of Health, Walter Reed Medical Center, and Children's National Medical Center. Neurosurgical pioneers at these institutions developed new technologies and diagnostic procedures which continue to inform our current practice. In addition, continued collaboration between the multiple training sites in Washington, DC has uniquely enriched our residents' training experience.

Postoperative Central Nervous System Infection After Neurosurgery in a Modernized, Resource-Limited Tertiary Neurosurgical Center in South Asia.

OBJECTIVE: Postoperative central nervous system infections (PCNSIs) are rare but serious complications after neurosurgery. The purpose of this study was to examine the prevalence and causative pathogens of PCNSIs at a modernized, resource-limited neurosurgical center in South Asia. METHODS: A retrospective analysis was conducted of the medical records of all 363 neurosurgical cases performed between June 1, 2012, and June 30, 2013, at a neurosurgical center in South Asia. Data from all operative neurosurgical cases during the 13-month period were included. RESULTS: Cerebrospinal fluid (CSF) analysis indicated that 71 of the 363 surgical cases had low CSF glucose or CSF leukocytosis. These 71 cases were categorized as PCNSIs. The PCNSIs with positive CSF cultures (9.86%) all had gram-negative bacteria with Pseudomonas aeruginosa (n = 5), Escherichia coli (n = 1), or Klebsiella pneumoniae (n = 1). The data suggest a higher rate of death (P = 0.031), a higher rate of CSF leak (P < 0.001), and a higher rate of cranial procedures (P < 0.001) among the infected patients and a higher rate of CSF leak among the patients with culture-positive infections (P = 0.038). CONCLUSIONS: This study summarizes the prevalence, causative organism of PCNSI, and antibiotic usage for all of the neurosurgical cases over a 13-month period in a modernized yet resource-limited neurosurgical center located in South Asia. The results from this study highlight the PCNSI landscape in an area of the world that is often underreported in the neurosurgical literature because of the paucity of clinical neurosurgical research undertaken there. This study shows an increasing prevalence of gram-negative organisms in CSF cultures from PCNSIs, which supports a trend in the recent literature of increasing gram-negative bacillary meningitis.

An improved functional neurological examination for use in nonhuman primate studies of focal reperfused cerebral ischemia.

There is renewed interest in primate models of acute stroke for the evaluation of potential therapeutic agents prior to clinical trials. The development of more precise functional outcome measures would improve the pre-clinical assessment of neuroprotective strategies. We have constructed a grading scale that utilizes an increased number of goal-oriented tasks to assess both behavior and motor function. The new scoring system is designed to enhance precision and accuracy when compared to existing scales. Twenty-seven male baboons were subjected to 1 h of middle cerebral artery territory occlusion followed by reperfusion. Outcome was evaluated using both a standard neurological function scale and a new task-oriented scale. Each scoring system was assessed for reproducibility (inter-observer reliability) and for association with radiographic infarct volume. The task-oriented grading system was significantly less variable than the standard outcome measure (p < 0.0001). The task-oriented neurological scale demonstrated stronger correlation with radiographic infarct volume (p < 0.0001) than the standard scale (p < 0.01) and more accurately reflected infarct size in animals with small strokes. Compared to the accepted system for grading neurological function, the task-oriented scale demonstrates improved inter-observer variability and a better association with radiographic outcome measures. Incorporating this refined neurological evaluation into a baboon model of stroke may serve to increase the functional predictive value of pre-clinical studies.

Interhemispheric intracranial pressure gradients in nonhuman primate stroke.

BACKGROUND: Although the development of significant interhemispheric intracranial pressure (ICP) gradients in the setting of unilateral stroke remains controversial, no study to date has investigated the existence of these gradients in a controlled, reproducible, clinically relevant model. Therefore, we used a primate model of reperfused hemispheric stroke to better characterize the development of these gradients. METHODS: Bilateral intraparenchymal ICP was continuously monitored in 7 adult male baboons subjected to left hemisphere reperfused stroke. Interhemispheric ICP gradients were calculated for each baboon and plotted over time. Infarct volume was determined using T2-weighted magnetic resonance imaging (MRI) at sacrifice. RESULTS: A bimodal distribution of interhemispheric ICP gradients was observed in animals with >20% infarct volume (22.1% +/- 0.9; range 21-23%) versus < or = 15% infarct volume (6.6% +/- 2.7; range 1-15%). In animals with >20% infarct volume, interhemispheric gradients developed early and persisted throughout the monitoring period. At 12 hours postreperfusion, animals with large infarcts demonstrated a mean pressure gradient of 13.8 +/- 4.3 mm Hg, compared to a mean gradient of -2.6 +/- 1.1 mm Hg for animals with < or =15% infarct volume. The difference in pressure gradients was statistically significant at all time points from 4 to 12 hours postreperfusion (p < 0.01). CONCLUSIONS: These data suggest that, in nonhuman primates, infarcts of a size approaching 20% of the hemisphere may be associated with significant ICP gradients. With these larger infarcts, ipsilateral monitoring is required if regional cerebral perfusion pressure is to be accurately assessed.