George M. Ghobrial

Biology of Cerebral Arteriovenous Malformations with a Focus on Inflammation

Cerebral arteriovenous malformations (AVMs) entail a significant risk of intracerebral hemorrhage owing to the direct shunting of arterial blood into the venous vasculature without the dissipation of the arterial blood pressure. The mechanisms involved in the growth, progression and rupture of AVMs are not clearly understood, but a number of studies point to inflammation as a major contributor to their pathogenesis. The upregulation of proinflammatory cytokines induces the overexpression of cell adhesion molecules in AVM endothelial cells, resulting in enhanced recruitment of leukocytes. The increased leukocyte-derived release of metalloproteinase-9 is known to damage AVM walls and lead to rupture. Inflammation is also involved in altering the AVM angioarchitecture via the upregulation of angiogenic factors that affect endothelial cell proliferation, migration and apoptosis. The effects of inflammation on AVM pathogenesis are potentiated by certain single-nucleotide polymorphisms in the genes of proinflammatory cytokines, increasing their protein levels in the AVM tissue. Furthermore, studies on metalloproteinase-9 inhibitors and on the involvement of Notch signaling in AVMs provide promising data for a potential basis for pharmacological treatment of AVMs. Potential therapeutic targets and areas requiring further investigation are highlighted.

ASA grade and Charlson Comorbidity Index of spinal surgery patients: correlation with complications and societal costs

BACKGROUND CONTEXT The Charlson Comorbidity Index (CCI) and the American Society of Anesthesiologists (ASA) Physical Status Classification System (ASA grade) are useful for predicting morbidity and mortality for a variety of disease processes. PURPOSE To evaluate CCI and ASA grade as predictors of complications after spinal surgery and examine the correlation between these comorbidity indices and the cost of care. STUDY DESIGN/SETTING Prospective observational study. PATIENT SAMPLE All patients undergoing any spine surgery at a single academic tertiary center over a 6-month period. OUTCOME MEASURES Direct health-care costs estimated from diagnosis related group and Current Procedural Terminology (CPT) codes. METHODS Demographic data, including all patient comorbidities, procedural data, and all complications, occurring within 30 days of the index procedure were prospectively recorded. Charlson Comorbidity Index was calculated from International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes and ASA grades determined from the operative record. Diagnosis related group and CPT codes were captured for each patient. Direct costs were estimated from a societal perspective using Medicare rates of reimbursement. A multivariable analysis was performed to assess the association of the CCI and ASA grade to the rate of complication and direct health-care costs. RESULTS Two hundred twenty-six cases were analyzed. The average CCI score for the patient cohort was 0.92, and the average ASA grade was 2.65. The CCI and ASA grade were significantly correlated, with Spearman ρ of 0.458 (p<.001). Both CCI and ASA grade were associated with increasing body mass index (p<.01) and increasing patient age (p<.0001). Increasing CCI was associated with an increasing likelihood of occurrence of any complication (p=.0093) and of minor complications (p=.0032). Increasing ASA grade was significantly associated with an increasing likelihood of occurrence of a major complication (p=.0035). Increasing ASA grade showed a significant association with increasing direct costs (p=.0062). CONCLUSIONS American Society of Anesthesiologists and CCI scores are useful comorbidity indices for the spine patient population, although neither was completely predictive of complication occurrence. A spine-specific comorbidity index, based on ICD-9-CM coding that could be easily captured from patient records, and which is predictive of patient likelihood of complications and mortality, would be beneficial in patient counseling and choice of operative intervention.

Intraoperative Vancomycin Use in Spinal Surgery: Single Institution Experience and Microbial Trends.

Study Design. Retrospective case series. Objective. To demonstrate the microbial trends of spinal surgical site infections in patients who had previously received crystallized vancomycin in the operative bed. Summary of Background Data. Prior large, case control series demonstrate the significant decrease in surgical site infection with the administration of vancomycin in the wound bed. Methods. A single institution, electronic database search was conducted for all patients who underwent spinal surgery who had received prophylactic crystalline vancomycin powder in the wound bed. Patients with a prior history of wound infection, intrathecal pumps, or spinal stimulators were excluded. Results. A total of 981 consecutive patients (494 males, 487 females; mean age, 59.4 yr; range, 16–95 yr) were identified from January 2011 to June 2013. The average dose of vancomycin powder was 1.13 g (range, 1–6 g). Sixty-six patients (6.71%) were diagnosed with a surgical site infection, of which 51 patients had positive wound cultures (5.2%). Of the 51 positive cultures, the most common organism was Staphylococcus aureus. The average dose of vancomycin was 1.3 g in the 38 cases where a gram-positive organism was cultured. A number of gram-negative infections were encountered such as Serratia marcescens, Enterobacter aerogenes, Bacteroides fragilis, Enterobacter cloacae, Citrobacter koseri, and Pseudomonas aeruginosa. The average dose of vancomycin was 1.2 g in 23 cases where a gram-negative infection was cultured. Fifteen of the 51 positive cultures (29.4%) were polymicrobial. Eight (53%) of these 15 polymicrobial cultures contained 3 or more distinct organisms. Conclusion. Prophylactic intraoperative vancomycin use in the wound bed in spinal surgery may increase the incidence of gram-negative or polymicrobial spinal infections. The use of intraoperative vancomycin may correlate with postoperative seromas, due to the high incidence of nonpositive cultures. Large, randomized, prospective trials are needed to demonstrate causation and dose-response relationship. Level of Evidence: 4

Neurosurgical Training With a Novel Cervical Spine Simulator: Posterior Foraminotomy and Laminectomy

BACKGROUND: Neurosurgical residents have traditionally been instructed on surgical techniques and procedures through an apprenticeship model. Currently, there has been research and interest in expanding the neurosurgical education model. OBJECTIVE: To establish a posterior cervical decompression educational curriculum with a novel cervical simulation model. METHODS: The Congress of Neurological Surgeons developed a simulation committee to explore and develop simulation-based models. The educational curriculum was developed to have didactic and technical components with the incorporation of simulation models. Through numerous reiterations, a posterior cervical decompression model was developed and a 2-hour education curriculum was established. RESULTS: Individual’s level of training varied, with 5 postgraduate year (PGY) 2 participants, 1 PGY-3 participant, 2 PGY-5 participants, and 1 attending, with the majority being international participants (6 of 9, 67%). Didactic scores overall improved (7 of 9, 78%). The technical scores of all participants improved from 11 to 24 (mean, 14.1) to 19 to 25 (mean, 22.4). Overall, in the posterior cervical decompression simulator, there was a significant improvement in the didactic scores (P = .005) and the technical scores (P = .02). CONCLUSION: The posterior cervical decompression simulation model appears to be a valuable tool in educating neurosurgery residents in the aspects of this procedure. The combination of a didactic and technical assessment is a useful teaching strategy in terms of educational development.BACKGROUND Neurosurgical residents have traditionally been instructed on surgical techniques and procedures through an apprenticeship model. Currently, there has been research and interest in expanding the neurosurgical education model. OBJECTIVE To establish a posterior cervical decompression educational curriculum with a novel cervical simulation model. METHODS The Congress of Neurological Surgeons developed a simulation committee to explore and develop simulation-based models. The educational curriculum was developed to have didactic and technical components with the incorporation of simulation models. Through numerous reiterations, a posterior cervical decompression model was developed and a 2-hour education curriculum was established. RESULTS Individuals level of training varied, with 5 postgraduate year (PGY) 2 participants, 1 PGY-3 participant, 2 PGY-5 participants, and 1 attending, with the majority being international participants (6 of 9, 67%). Didactic scores overall improved (7 of 9, 78%). The technical scores of all participants improved from 11 to 24 (mean, 14.1) to 19 to 25 (mean, 22.4). Overall, in the posterior cervical decompression simulator, there was a significant improvement in the didactic scores (P = .005) and the technical scores (P = .02). CONCLUSION The posterior cervical decompression simulation model appears to be a valuable tool in educating neurosurgery residents in the aspects of this procedure. The combination of a didactic and technical assessment is a useful teaching strategy in terms of educational development.

Dural Arteriovenous Fistulas: A Review of the Literature and a Presentation of a Single Institution’s Experience

OBJECTIVE Dural arteriovenous fistulas (DAVFs) are arteriovenous shunts from a dural arterial supply to a dural venous channel, typically supplied by pachymeningeal arteries and located near a major venous sinus. A retrospective review was conducted to present the results of endovascular obliteration of DAVFs, with particular emphasis of newer liquid embolic agents, including Onyx-18 (MV3, Irvine, California, USA). METHODS A review of the literature was performed, and a presentation of the number of treatments, complications, and outcomes is included here. The number of arterial embolizations and need for transvenous embolization, open surgery, and radiosurgery was assessed as well as normalization of retrograde cortical venous drainage. RESULTS Thirty-nine patients (22 men and 17 women) underwent endovascular treatment of DAVFs at our institution from 2001 to 2009. Ages ranged from 39 to 71 years (mean, 48 years). Seventy-nine percent of patients had retrograde cortical venous drainage. The average number of embolizations in all patients was 2.1. Twelve patients underwent 40 embolization treatments with Onyx, with an obliteration rate of 75% and cortical venous drainage obliteration rate of 85%. Seventy-one percent (28/39) of patients had complete treatment of the fistula: 21 by purely endovascular treatment and 7 with endovascular therapy followed by craniotomy, as well as seven patients who underwent stereotactic radiosurgery after embolization. CONCLUSIONS Endovascular management of DAVFs is a safe and effective method of treating these complex lesions.

Stent-Assisted Endovascular Recanalization of Extracranial Internal Carotid Artery Occlusion in Acute Ischemic Stroke

OBJECTIVE Carotid artery occlusions traditionally have extremely poor outcomes with intravenous tissue plasminogen activator treatment or emergent thromboendarterectomy. We retrospectively reviewed our institutional experience with acute carotid occlusions using internal carotid artery endovascular thrombolysis and stent placement. METHODS We studied the radiographic and clinical characteristics of 17 patients with an acute cervical internal carotid artery occlusion treated with stent-assisted endovascular thrombolysis. Clinical outcomes were assessed by using National Institute of Health Stroke Scale (NIHSS) scores, which were obtained on admission and discharge. Inclusion criteria were an NIHSS score of at least 6 and the presence of significant penumbra on computed tomographic perfusion. Morbidity and mortality data were collected and analyzed. RESULTS Seventeen candidates met our inclusion criteria, 16 (94%) of whom had successful immediate recanalization of the internal carotid artery. On admission, the mean NIHSS score was 16.5 and the mean modified Rankin Scale score was 4.8. The mean NIHSS score improved to 6.9 on discharge, with a mean modified Rankin Scale score of 2.88. Eight (47%) patients recovered ambulatory function on discharge. The overall mortality rate of our series was 17%. CONCLUSIONS In the setting of acute ischemic stroke, emergent carotid artery thrombolysis and stenting is a promising treatment for acute carotid occlusions with excellent recanalization rates and favorable clinical outcomes.

Management of incidental cavernous malformations: a review

Cavernous malformations (CMs) are angiographically occult vascular malformations that are frequently found incidentally on MR imaging. Despite this benign presentation, these lesions could cause symptomatic intracranial hemorrhage, seizures, and focal neurological deficits. Cavernomas can be managed conservatively with neuroimaging studies, surgically with lesion removal, or with radiosurgery. Considering recent studies examining the CMs natural history, imaging techniques, and possible therapeutic interventions, the authors provide a concise review of the literature and discuss the optimal management of incidental CMs.

Nasal MRSA colonization: Impact on surgical site infection following spine surgery

BACKGROUND Prior studies published in the cardiothoracic, orthopedic and gastrointestinal surgery have identified the importance of nasal (methicillin-resistant Staphylococcus aureus) MRSA screening and subsequent decolonization to reduce MRSA surgical site infection (SSI). This is the first study to date correlating nasal MRSA colonization with postoperative spinal MRSA SSI. OBJECTIVE To assess the significance of nasal MRSA colonization in the setting of MRSA SSI. METHODS A retrospective electronic chart review of patients from year 2011 to June 2013 was conducted for patients with both nasal MRSA colonization within 30 days prior to spinal surgery. Patients who tested positive for MRSA were put on contact isolation protocol. None of these patients received topical antibiotics for decolonization of nasal MRSA. RESULTS A total of 519 patients were identified; 384 negative (74%), 110 MSSA-positive (21.2%), and 25 (4.8%) MRSA-positive. Culture positive surgical site infection (SSI) was identified in 27 (5.2%) cases and was higher in MRSA-positive group than in MRSA-negative and MSSA-positive groups (12% vs. 5.73% vs. 1.82%; p=0.01). The MRSA SSI rate was 0.96% (n=5). MRSA SSI developed in 8% of the MRSA-positive group as compared to only in 0.61% of MRSA-negative group, with a calculated odds ratio of 14.23 (p=0.02). In the presence of SSI, nasal MRSA colonization was associated with MRSA-positive wound culture (66.67 vs. 12.5%; p<0.0001). CONCLUSION Preoperative nasal MRSA colonization is associated with postoperative spinal MRSA SSI. Preoperative screening and subsequent decolonization using topical antibiotics may help in decreasing the incidence of MRSA SSI after spine surgery. Nasal MRSA+ patients undergoing spinal surgery should be informed regarding their increased risk of developing surgical site infection.

Simulated Spinal Cerebrospinal Fluid Leak Repair: An Educational Model With Didactic and Technical Components

BACKGROUND: In the era of surgical resident work hour restrictions, the traditional apprenticeship model may provide fewer hours for neurosurgical residents to hone technical skills. Spinal dura mater closure or repair is 1 skill that is infrequently encountered, and persistent cerebrospinal fluid leaks are a potential morbidity. OBJECTIVE: To establish an educational curriculum to train residents in spinal dura mater closure with a novel durotomy repair model. METHODS: The Congress of Neurological Surgeons has developed a simulation-based model for durotomy closure with the ongoing efforts of their simulation educational committee. The core curriculum consists of didactic training materials and a technical simulation model of dural repair for the lumbar spine. RESULTS: Didactic pretest scores ranged from 4/11 (36%) to 10/11 (91%). Posttest scores ranged from 8/11 (73%) to 11/11 (100%). Overall, didactic improvements were demonstrated by all participants, with a mean improvement between pre- and posttest scores of 1.17 (18.5%; P = .02). The technical component consisted of 11 durotomy closures by 6 participants, where 4 participants performed multiple durotomies. Mean time to closure of the durotomy ranged from 490 to 546 seconds in the first and second closures, respectively (P = .66), whereby the median leak rate improved from 14 to 7 (P = .34). There were also demonstrative technical improvements by all. CONCLUSION: Simulated spinal dura mater repair appears to be a potentially valuable tool in the education of neurosurgery residents. The combination of a didactic and technical assessment appears to be synergistic in terms of educational development.BACKGROUND In the era of surgical resident work hour restrictions, the traditional apprenticeship model may provide fewer hours for neurosurgical residents to hone technical skills. Spinal dura mater closure or repair is 1 skill that is infrequently encountered, and persistent cerebrospinal fluid leaks are a potential morbidity. OBJECTIVE To establish an educational curriculum to train residents in spinal dura mater closure with a novel durotomy repair model. METHODS The Congress of Neurological Surgeons has developed a simulation-based model for durotomy closure with the ongoing efforts of their simulation educational committee. The core curriculum consists of didactic training materials and a technical simulation model of dural repair for the lumbar spine. RESULTS Didactic pretest scores ranged from 4/11 (36%) to 10/11 (91%). Posttest scores ranged from 8/11 (73%) to 11/11 (100%). Overall, didactic improvements were demonstrated by all participants, with a mean improvement between pre- and posttest scores of 1.17 (18.5%; P = .02). The technical component consisted of 11 durotomy closures by 6 participants, where 4 participants performed multiple durotomies. Mean time to closure of the durotomy ranged from 490 to 546 seconds in the first and second closures, respectively (P = .66), whereby the median leak rate improved from 14 to 7 (P = .34). There were also demonstrative technical improvements by all. CONCLUSION Simulated spinal dura mater repair appears to be a potentially valuable tool in the education of neurosurgery residents. The combination of a didactic and technical assessment appears to be synergistic in terms of educational development.

Simulated Lumbar Minimally Invasive Surgery Educational Model With Didactic and Technical Components

BACKGROUND The learning and development of technical skills are paramount for neurosurgical trainees. External influences and a need for maximizing efficiency and proficiency have encouraged advancements in simulator-based learning models. OBJECTIVE To confirm the importance of establishing an educational curriculum for teaching minimally invasive techniques of pedicle screw placement using a computer-enhanced physical model of percutaneous pedicle screw placement with simultaneous didactic and technical components. METHODS A 2-hour educational curriculum was created to educate neurosurgical residents on anatomy, pathophysiology, and technical aspects associated with image-guided pedicle screw placement. Predidactic and postdidactic practical and written scores were analyzed and compared. Scores were calculated for each participant on the basis of the optimal pedicle screw starting point and trajectory for both fluoroscopy and computed tomographic navigation. RESULTS Eight trainees participated in this module. Average mean scores on the written didactic test improved from 78% to 100%. The technical component scores for fluoroscopic guidance improved from 58.8 to 52.9. Technical score for computed tomography-navigated guidance also improved from 28.3 to 26.6. CONCLUSION Didactic and technical quantitative scores with a simulator-based educational curriculum improved objectively measured resident performance. A minimally invasive spine simulation model and curriculum may serve a valuable function in the education of neurosurgical residents and outcomes for patients.BACKGROUND: The learning and development of technical skills are paramount for neurosurgical trainees. External influences and a need for maximizing efficiency and proficiency have encouraged advancements in simulator-based learning models. OBJECTIVE: To confirm the importance of establishing an educational curriculum for teaching minimally invasive techniques of pedicle screw placement using a computerenhanced physical model of percutaneous pedicle screw placement with simultaneous didactic and technical components. METHODS: A 2-hour educational curriculum was created to educate neurosurgical residents on anatomy, pathophysiology, and technical aspects associated with imageguided pedicle screw placement. Predidactic and postdidactic practical and written scores were analyzed and compared. Scores were calculated for each participant on the basis of the optimal pedicle screw starting point and trajectory for both fluoroscopy and computed tomographic navigation. RESULTS: Eight trainees participated in this module. Average mean scores on the written didactic test improved from 78% to 100%. The technical component scores for fluoroscopic guidance improved from 58.8 to 52.9. Technical score for computed tomography—navigated guidance also improved from 28.3 to 26.6. CONCLUSION: Didactic and technical quantitative scores with a simulator-based educational curriculum improved objectively measured resident performance. A minimally invasive spine simulation model and curriculum may serve a valuable function in the education of neurosurgical residents and outcomes for patients.