Cigarette Smoking and Observed Growth of Unruptured Intracranial Aneurysms: A Systematic Literature Review and Meta-Analysis.

BACKGROUND: Smoking and observed growth of intracranial aneurysms are known risk factors for rupture. The mechanism by which smoking increases this risk is not completely elucidated. Furthermore, an association between smoking and aneurysm growth has not been clearly defined in the literature. We hypothesize that smoking is associated with aneurysm growth, which, in turn, may serve as one of the mechanisms by which smoking drives rupture risk. METHODS: We report a systematic review of the literature in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Using the R software, we performed a meta-analysis to investigate the association between smoking and the growth of unruptured intracranial aneurysms. Studies on familial aneurysms and genetic syndromes known to increase the risk of aneurysms were excluded. RESULTS: Eighteen observational studies were included with a total of 3535 patients and 4289 aneurysms with a mean follow-up period ranging from 17 to 226 months. The mean age among the studies ranged from 38.4 to 73.9 years; 74% of patients were female. Ever-smoking status (odds ratio, 1.10 [95% CI, 0.87-1.38]) and current smoking status (odds ratio, 1.43 [95% CI, 0.84-2.43]) did not show a statistically significant association with growth of intracranial aneurysms. Patients currently smoking did not have a statistically significant association with the growth of intracranial aneurysms (odds ratio, 1.18 [95% CI, 0.72-1.93]) compared with patients without a smoking history. No significant association was found in patients who previously smoked compared with patients who never smoked (odds ratio, 1.46 [95% CI, 0.88-2.43]). CONCLUSIONS: Smoking is not clearly associated with the growth of unruptured intracranial aneurysms, despite trends being observed, there is no statistical association. The mechanism by which smoking increases rupture risk might not be growth. In patients for whom observation is recommended, the absence of growth over time in the setting of smoking history does not, therefore, imply protection from rupture.

Retrograde trans-posterior communicating artery rescue balloon angioplasty of incompletely expanded pipeline embolization device: complication management.

BACKGROUND: Pipeline embolization device (PED) deployment is a technically demanding procedure. Incomplete device expansion or deployment is one intra-operative risk, especially in patients with significant vascular tortuosity. CASE DESCRIPTION: We describe the case of a 71-year female with an unruptured left vertebral artery saccular aneurysm. Tortuosity of the arteries proximal to the aneurysm complicated deployment and the proximal end of the PED failed to expand despite several maneuvers. The inadequately expanded PED caused flow limitation in the left vertebral artery and it became imperative to achieve wall apposition of the PED. We salvaged the PED from the left vertebral artery by retrograde trans-right posterior communicating artery balloon angioplasty. CONCLUSIONS: Our case documents the successful application of the rarely used salvage strategy - anterior-to-posterior circulation retrograde rescue balloon angioplasty of an unopened PED.

Clinical outcomes of first- and second-generation hydrogel coils compared with bare platinum coils: a systematic literature review.

Endovascular coiling has revolutionized intracranial aneurysm treatment; however, recurrence continues to represent a major limitation. The hydrogel coil was developed to increase packing density and improve neck healing and therefore decrease recurrence rates. In this paper, we review treatment outcomes of first- (1HCs) and second-generation (2HCs) hydrogel coils and compare them to those of bare platinum coils (BPC). A query of multiple databases was performed. Articles with at least 10 aneurysms treated with either 1HC or 2HC were selected for analysis. Collected data included aneurysm size, rupture status, initial occlusion, initial residual neck/aneurysm, packing density, mortality, morbidity, recurrence, and retreatment rates. The primary endpoint was recurrence at final follow-up. Secondary endpoints included residual neck and dome rates as well as procedure-related complications and functional dependence at final follow-up. Studies that compared 1HC to BPC showed significant lower recurrence (24% vs. 30.8%, p = 0.02) and higher packing density (58.5% vs. 24.1%, p < 0.001) in 1HC but no significant difference in initial occlusion rate (p = 0.08). Studies that compared 2HC to BPC showed lower recurrence (6.3% vs. 14.3%, p = 0.007) and retreatment rates (3.4% vs. 7.7%, p = 0.010) as well as higher packing density (36.4% vs. 29.2%, p = 0.002) in 2HC, with similar initial occlusion rate (p = 0.86). The rate of complications was not statistically different between HC (25.5%) and BPC (22.6%, p = 0.06). Based on our review, the 1HC and 2HC achieved higher packing density and lower recurrence rates compared to BPC. The safety profile was similar between both groups.

Efficacy and safety of middle meningeal artery embolization in the management of refractory or chronic subdural hematomas: a systematic review and meta-analysis.

INTRODUCTION: Refractory or chronic subdural hematomas (cSDH) constitute a challenging entity that neurosurgeons face frequently nowadays. Middle meningeal artery embolization (MMAE) has emerged in the recent years as a promising treatment option. However, solid evidence that can dictate management guidelines is still lacking. METHODS: We conducted a systematic review and meta-analysis (MA) in compliance with the PRISMA guidelines to evaluate the efficacy and safety of MMAE compared with conventional treatments for refractory or cSDH. Databases were searched up to March 2019. Using a random-effects model, meta-analyses of proportions and risk difference were conducted recurrence, need for surgical rescue, and complications. RESULTS: Eleven studies (177 patients) were included. Majority (116, 69%) were males with a weighted mean age of 71 + -19.5 years. Meta-analysis of proportions showed treatment failure to be 2.8%, need for surgical rescue 2.7%, and embolization-related complications 1.2%. Meta-analysis of risk-difference between embolized and non-embolized patients showed a 26% (p < 0.001, 95% CI 21%-31%, I2 = 0) lower risk of hematoma recurrence in MMAE. Similarly, in the embolized group, the need for surgical rescue was 20% less (p < 0.001, 95% CI = 12%-27%, I2 = 12.4), and complications were 3.6% less (p = 0.008, 95% CI 1%-6%, I2 = 0) compared to conventional groups. CONCLUSIONS: Although MMAE appears to be a promising treatment for refractory or cSDH, drawing definitive conclusions remains limited by paucity of data and small sample sizes. Multicenter, randomized, prospective trials are needed to compare embolization to conventional treatments like watchful waiting, medical management, or surgical evacuation. More extensive research on MMAE could begin a new era in the minimally invasive management of cSDH.

Roberts Bartholow: the progenitor of human cortical stimulation and his contentious experiment.

Roberts Bartholow, a physician, born and raised in Maryland, was a surgeon and Professor in Medicine who had previously served the Union during the Civil War. His interest in scientific research drove him to perform the first experiment that tested the excitability of the human brain cortex. His historical experiment on one of his patients, Mary Rafferty, with a cancerous ulcer on the skull, was one of his great accomplishments. His inference from this experiment and proposed scientific theory of cortical excitation and localization in humans was one of the most critically acclaimed topics in the medical community, which attracted the highest commendation for the unique discovery as well as criticism for possible ethical violations. Despite that criticism, his theory and methods of cortical localization are the cornerstone of modern brain mapping and have, in turn, led to countless medical innovations.

A meta-analysis of outcomes and complications of magnetic resonance-guided focused ultrasound in the treatment of essential tremor.

OBJECTIVE Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel technique that uses high-intensity focused ultrasound to achieve target ablation. Like a lens focusing the sun's rays, the ultrasound waves are focused to generate heat. This therapy combines the noninvasiveness of Gamma Knife thalamotomy and the real-time ablation of deep brain stimulation with acceptable complication rates. The aim of this study was to analyze the overall outcomes and complications of MRgFUS in the treatment of essential tremor (ET). METHODS A meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was made by searching PubMed, Cochrane library database, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Patients with the diagnosis of ET who were treated with MRgFUS were included in the study. The change in the Clinical Rating Scale for Tremor (CRST) score after treatment was analyzed. The improvement in disability was assessed with the Quality of Life in Essential Tremor Questionnaire (QUEST) score. The pooled data were analyzed by the DerSimonian-Laird random-effects model. Tests for bias and heterogeneity were performed. RESULTS Nine studies with 160 patients who had ET were included in the meta-analysis. The ventral intermediate nucleus was the target in 8 of the studies. The cerebellothalamic tract was targeted in 1 study. There was 1 randomized controlled trial, 6 studies were retrospective, and 2 were prospective. The mean number of sonications given in various studies ranged from 11 ± 3.2 to 22.5 ± 7.5 (mean ± SD). The maximum delivered energy ranged from 10,320 ± 4537 to 14,497 ± 6695 Joules. The mean of peak temperature reached ranged from 53°C ± 2.3°C to 62.0°C ± 2.5°C. On meta-analysis with the random-effects model, the pooled percentage improvements in the CRST Total, CRST Part A, CRST Part C, and QUEST scores were 62.2%, 62.4%, 69.1%, and 46.5%, respectively. Dizziness was the most common in-procedure complication, occurring in 45.5%, followed by nausea and vomiting in 26.85% (pooled percentage). At 3 months, ataxia was the most common complication, occurring in 32.8%, followed by paresthesias in 25.1% of the patients. At 12 months posttreatment, the ataxia had significantly recovered and paresthesias became the most common persisting complication, at 15.3%. CONCLUSIONS The MRgFUS therapy for ET significantly improves the CRST scores and improves the quality of life in patients with ET, with an acceptable complication rate. Therapy with MRgFUS is a promising frontier in functional neurosurgery.

Safety profile of superior petrosal vein (the vein of Dandy) sacrifice in neurosurgical procedures: a systematic review.

OBJECTIVE Walter E. Dandy described for the first time the anatomical course of the superior petrosal vein (SPV) and its significance during surgery for trigeminal neuralgia. The patient's safety after sacrifice of this vein is a challenging question, with conflicting views in current literature. The aim of this systematic review was to analyze the current surgical considerations regarding Dandy's vein, as well as provide a concise review of the complications after its obliteration. METHODS A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A thorough literature search was conducted on PubMed, Web of Science, and the Cochrane database; articles were selected systematically based on the PRISMA protocol and reviewed completely, and then relevant data were summarized and discussed. RESULTS A total of 35 publications pertaining to the SPV were included and reviewed. Although certain studies report almost negligible complications of SPV sectioning, there are reports demonstrating the deleterious effects of SPV obliteration when achieving adequate exposure in surgical pathologies like trigeminal neuralgia, vestibular schwannoma, and petroclival meningioma. The incidence of complications after SPV sacrifice (32/50 cases in the authors' series) is 2/32 (6.2%), and that reported in various case series varies from 0.01% to 31%. It includes hemorrhagic and nonhemorrhagic venous infarction of the cerebellum, sigmoid thrombosis, cerebellar hemorrhage, midbrain and pontine infarct, intracerebral hematoma, cerebellar and brainstem edema, acute hydrocephalus, peduncular hallucinosis, hearing loss, facial nerve palsy, coma, and even death. In many studies, the difference in incidence of complications between the SPV-sacrificed group and the SPV-preserved group was significant. CONCLUSIONS The preservation of Dandy's vein is a neurosurgical dilemma. Literature review and experiences from large series suggest that obliterating the vein of Dandy while approaching the superior cerebellopontine angle corridor may be associated with negligible complications. However, the counterview cannot be neglected in light of some series showing an up to 30% complication rate from SPV sacrifice. This review provides the insight that although the incidence of complications due to SPV obliteration is low, they can happen, and the sequelae might be worse than the natural history of the existing pathology. Therefore, SPV preservation should be attempted to optimize patient outcome.

A comparison of the techniques of direct pars interarticularis repairs for spondylolysis and low-grade spondylolisthesis: a meta-analysis.

OBJECTIVE Spondylosis with or without spondylolisthesis that does not respond to conservative management has an excellent outcome with direct pars interarticularis repair. Direct repair preserves the segmental spinal motion. A number of operative techniques for direct repair are practiced; however, the procedure of choice is not clearly defined. The present study aims to clarify the advantages and disadvantages of the different operative techniques and their outcomes. METHODS A meta-analysis was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The following databases were searched: PubMed, Cochrane Library, Web of Science, and CINAHL ( Cumulative Index to Nursing and Allied Health Literature). Studies of patients with spondylolysis with or without low-grade spondylolisthesis who underwent direct repair were included. The patients were divided into 4 groups based on the operative technique used: the Buck repair group, Scott repair group, Morscher repair group, and pedicle screw-based repair group. The pooled data were analyzed using the DerSimonian and Laird random-effects model. Tests for bias and heterogeneity were performed. The I2 statistic was calculated, and the results were analyzed. Statistical analysis was performed using StatsDirect version 2. RESULTS Forty-six studies consisting of 900 patients were included in the study. The majority of the patients were in their 2nd decade of life. The Buck group included 19 studies with 305 patients; the Scott group had 8 studies with 162 patients. The Morscher method included 5 studies with 193 patients, and the pedicle group included 14 studies with 240 patients. The overall pooled fusion, complication, and outcome rates were calculated. The pooled rates for fusion for the Buck, Scott, Morscher, and pedicle screw groups were 83.53%, 81.57%, 77.72%, and 90.21%, respectively. The pooled complication rates for the Buck, Scott, Morscher, and pedicle screw groups were 13.41%, 22.35%, 27.42%, and 12.8%, respectively, and the pooled positive outcome rates for the Buck, Scott, Morscher, and pedicle screw groups were 84.33%, 82.49%, 80.30%, and 80.1%, respectively. The pedicle group had the best fusion rate and lowest complication rate. CONCLUSIONS The pedicle screw-based direct pars repair for spondylolysis and low-grade spondylolisthesis is the best choice of procedure, with the highest fusion and lowest complication rates, followed by the Buck repair. The Morscher and Scott repairs were associated with a high rate of complication and lower rates of fusion.

Preoperative diffusion tensor imaging-fiber tracking for facial nerve identification in vestibular schwannoma: a systematic review on its evolution and current status with a pooled data analysis of surgical concordance rates.

OBJECTIVE Total tumor excision with the preservation of neurological function and quality of life is the goal of modern-day vestibular schwannoma (VS) surgery. Postoperative facial nerve (FN) paralysis is a devastating complication of VS surgery. Determining the course of the FN in relation to a VS preoperatively is invaluable to the neurosurgeon and is likely to enhance surgical safety with respect to FN function. Diffusion tensor imaging-fiber tracking (DTI-FT) technology is slowly gaining traction as a viable tool for preoperative FN visualization in patients with VS. METHODS A systematic review of the literature in the PubMed, Cochrane Library, and Web of Science databases was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and those studies that preoperatively localized the FN in relation to a VS using the DTI-FT technique and verified those preoperative FN tracking results by using microscopic observation and electrophysiological monitoring during microsurgery were included. A pooled analysis of studies was performed to calculate the surgical concordance rate (accuracy) of DTI-FT technology for FN localization. RESULTS Fourteen studies included 234 VS patients (male/female ratio 1:1.4, age range 17-75 years) who had undergone preoperative DTI-FT for FN identification. The mean tumor size among the studies ranged from 29 to 41.3 mm. Preoperative DTI-FT could not visualize the FN tract in 8 patients (3.4%) and its findings could not be verified in 3 patients (1.2%), were verified but discordant in 18 patients (7.6%), and were verified and concordant in 205 patients (87.1%). CONCLUSIONS Preoperative DTI-FT for FN identification is a useful adjunct in the surgical planning for large VSs (> 2.5 cm). A pooled analysis showed that DTI-FT successfully identifies the complete FN course in 96.6% of VSs (226 of 234 cases) and that FN identification by DTI-FT is accurate in 90.6% of cases (205 of 226 cases). Larger studies with DTI-FT-integrated neuronavigation are required to look at the direct benefit offered by this specific technique in preserving postoperative FN function.

Endovascular Retrieval of Migrated Distal End of Ventriculoperitoneal Shunt from Bilateral Pulmonary Arteries: A Technical Note.

Ventriculoperitoneal (VP) shunting of cerebrospinal fluid is one of the most common procedures performed by neurosurgeons around the world. Migration of distal VP shunt catheter into bilateral segmental pulmonary arteries is an extremely rare complication of VP shunt placement. In the present case, a 30-year-old male underwent VP shunting complicated by migration of distal VP shunt catheter into the bilateral pulmonary arteries. Despite manual attempt at externalizing the distal VP shunt catheter at the level of the clavicle, a small piece of distal VP shunt catheter in bilateral pulmonary arteries was noted on computed tomography of the chest obtained after manual externalization. This persistent distal VP shunt catheter was likely left behind after a break in the distal VP shunt catheter during manual externalization procedure. Given the small size of the segmental pulmonary arteries, a novel endovascular technique was used to move the distal VP shunt catheter from the bilateral segmental pulmonary arteries to the main pulmonary trunk. Once in the main pulmonary trunk, a snare device was used to retrieve the distal shunt catheter through the femoral vein. In this technical note, the authors highlight the relevant endovascular technical details to first move the VP shunt catheter from the bilateral segmental arteries followed by successful catheter retrieval using snare device.

The 21st-century challenge to neurocritical care: the rise of the superbug Acinetobacter baumannii. A meta-analysis of the role of intrathecal or intraventricular antimicrobial therapy in reduction of mortality.

OBJECTIVE Neurosurgical infections due to multidrug-resistant organisms have become a nightmare that neurosurgeons are facing in the 21st century. This is the dawn of the so-called postantibiotic era. There is an urgent need to review and evaluate ways to reduce the high mortality rates due to these infections. The present study evaluates the efficacy of combined intravenous plus intrathecal or intraventricular (IV + IT) therapy versus only intravenous (IV) therapy in treating postneurosurgical Acinetobacter baumannii infections. METHODS The authors performed a meta-analysis of all peer-reviewed studies from the PubMed, Cochrane Library database, ScienceDirect, and EMBASE in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Five studies were finally included in the present analysis: 126 patients were studied who had postneurosurgical A. baumannii infection. The Cochrane collaboration tool was used to evaluate risk of bias, and a test of heterogeneity was performed. The I2 statistic was calculated. The patients were divided into 2 groups: the IV group received only intravenous therapy and the IV + IT group received both intravenous and intrathecal or intraventricular antimicrobial therapy. The outcome was mortality attributed specifically to A. baumannii infection in postneurosurgical cases. The pooled data were analyzed using the Cochran-Mantel-Haenszel method in a fixed-effects model. RESULTS The total number of patients in the IV-only group was 73, and the number of patients in the IV + IT group was 53. The mean duration of intravenous therapy was 27 days. The mean duration of intrathecal colistin was 21 days. The intravenous dose of colistin ranged from 3.75 to 8.8 MIU per day. The dose of intrathecal colistin ranged between 125,000 and 250,000 IU per day. The overall calculated odds ratio for mortality for the IV + IT group after pooling the data was 0.16 (95% CI 0.06-0.40, p < 0.0001). The patients who received IV + IT therapy had an 84% lower risk of dying due to the infection compared with those who received only IV therapy. CONCLUSIONS There is an 84% lower risk of mortality in patients who have been treated with combined intrathecal or intraventricular plus intravenous antimicrobial therapy versus those who have been treated with intravenous therapy alone. The intrathecal or intraventricular route should be strongly considered when dealing with postneurosurgical multidrug-resistant A. baumannii infections.

Resection of posterior clinoid meningioma through retrosigmoid approach: concepts and nuances.

Meningiomas arising from the posterior clinoid process pose a great surgical challenge because of their location and propensity to cause critical neurovascular compression. The authors' patient was a 66-year-old female who had a large posterior clinoid meningioma with significant brainstem compression that was operated on through the retrosigmoid approach. This 3D surgical video emphasizes the various technical concepts that are important to preserving compressed neural and vascular structures during the surgery. It would also be interesting to note the extent of visualization around the posterior clinoid region gained through a retrosigmoid corridor. The video can be found here: https://youtu.be/CBmT_0ov0YA .

Spinal meningiomas: clinicoradiological factors predicting recurrence and functional outcome.

OBJECTIVE Spinal meningiomas are benign tumors with a wide spectrum of clinical and radiological features at presentation. The authors analyzed multiple clinicoradiological factors to predict recurrence and functional outcome in a cohort with a mean follow-up of more than 4 years. The authors also discuss the results of clinical studies regarding spinal meningiomas in the last 15 years. METHODS The authors retrospectively reviewed the clinical and radiological details of patients who underwent surgery for spinal tumors between 2001 and 2015 that were histopathologically confirmed as meningiomas. Demographic parameters, such as age, sex, race, and association with neurofibromatosis Type 2, were considered. Radiological parameters, such as tumor size, signal changes of spinal cord, spinal level, number of levels, location of tumor attachment, shape of tumor, and presence of dural tail/calcification, were noted. These factors were analyzed to predict recurrence and functional outcome. Furthermore, a pooled analysis was performed from 13 reports of spinal meningiomas in the last 15 years. RESULTS A total of 38 patients were included in this study. Male sex and tumors with radiological evidence of a dural tail were associated with an increased risk of recurrence at a mean follow-up of 51.2 months. Ventral or ventrolateral location, large tumors, T2 cord signal changes, and poor preoperative functional status were associated with poor functional outcome at 1-year follow-up. CONCLUSIONS Spine surgeons must be aware of the natural history and risk factors of spinal meningiomas to establish a prognosis for their patients.

Epidemiology of adult-onset hydrocephalus: institutional experience with 2001 patients.

OBJECTIVE Adult-onset hydrocephalus is not commonly discussed in the literature, especially regarding its demographic distribution. In contrast to pediatric hydrocephalus, which is related to a primary CSF pathway defect, its development in adults is often secondary to other pathologies. In this study, the authors investigated the epidemiology of adult-onset hydrocephalus as it pertains to different etiologies and in reference to age, sex, and race distributions. METHODS The authors retrospectively reviewed the clinical notes of 2001 patients with adult-onset hydrocephalus who presented to Louisiana State University Health Sciences Center within a 25-year span. Significant differences between the groups were analyzed by a chi-square test; p < 0.05 was considered significant. RESULTS The overall mean (± SEM) incidence of adult hydrocephalus in this population was 77 ± 30 per year, with a significant increase in incidence in the past decade (55 ± 3 [1990-2003] vs 102 ± 6 [2004-2015]; p < 0.0001). Hydrocephalus in a majority of the patients had a vascular etiology (45.5%) or was a result of a tumor (30.2%). The incidence of hydrocephalus in different age groups varied according to various pathologies. The incidence was significantly higher in males with normal-pressure hydrocephalus (p = 0.03) or head injury (p = 0.01) and higher in females with pseudotumor cerebri (p < 0.0001). In addition, the overall incidence of hydrocephalus was significantly higher in Caucasian patients (p = 0.0002) than in those of any other race. CONCLUSIONS Knowledge of the demographic variations in adult-onset hydrocephalus is helpful in achieving better risk stratification and better managing the disease in patients. For general applicability, these results should be validated in a large-scale meta-analysis based on a national population database.

Role of radiological parameters in predicting overall shunt outcome after ventriculoperitoneal shunt insertion in pediatric patients with obstructive hydrocephalus.

OBJECTIVE Despite significant advances in the medical field and shunt technology, shunt malfunction remains a nightmare of pediatric neurosurgeons. In this setting, the ability to preoperatively predict the probability of shunt malfunction is quite compelling. The authors have compared the preoperative radiological findings in obstructive hydrocephalus and the subsequent clinical course of the patient to determine any association with overall shunt outcome. METHODS This retrospective study included all pediatric patients (age < 18 years) who had undergone ventriculoperitoneal shunt insertion for obstructive hydrocephalus. Linear measurements were taken from pre- and postoperative CT or MRI studies to calculate different indices and ratios including Evans' index, frontal horn index (FHI), occipital horn index (OHI), frontooccipital horn ratio (FOHR), and frontooccipital horn index ratio (FOIR). Other morphological features such as bi- or triventriculomegaly, right-left ventricular symmetry, and periventricular lucency (PVL) were also noted. The primary clinical outcomes that were reviewed included the need for shunt revision, time interval to first shunt revision, frequency of shunt revisions, and revision-free survival. RESULTS A total of 121 patients were eligible for the analysis. Nearly half of the patients (47.9%) required shunt revision. The presence of PVL was associated with lower revision rates than those in others (39.4% vs 58.2%, p = 0.03). None of the preoperative radiological indices or ratios showed any correlation with shunt revision. Nearly half of the patients with shunt revision required early revision (< 90 days of primary surgery). The reduction in the FOHR was high in patients who required early shunt revision (20.16% in patients with early shunt revision vs 6.4% in patients with late shunt revision, p = 0.009). Nearly half of the patients (48.3%) requiring shunt revision ultimately needed more than one revision procedure. Greater occipital horn dilation on preoperative images was associated with a lower frequency of shunt revision, as dictated by a high OHI and a low FOIR in patients with a single shunt revision as compared with those in patients who required multiple shunt revisions (p = 0.029 and 0.009, respectively). The mean follow-up was 49.9 months. Age was a significant factor affecting shunt revision-free survival. Patients younger than 6 months of age had significantly less revision-free survival than the patients older than 6 months (median survival of 10.1 vs 94.1 months, p = 0.004). CONCLUSIONS Preoperative radiological linear indices and ratios do not predict the likelihood of subsequent shunt malfunction. However, patients who required early shunt revision tended to have greater reductions in ventricular volumes on postoperative images. Therefore a greater reduction in ventricular volume is not actually desirable, and a ventricular volume high enough to reduce intracranial pressure is instead to be aimed at for long-term shunt compliance.

Simulation in neurosurgery: Past, present, and future.

Neurosurgery is one of the most technically demanding medical professions that warrants a high level of expertise. In the present context of competitive medical practice, high societal expectations regarding quality of patient care and medicolegal and financial constraints, there are fewer opportunities for a trainee to achieve competency in standard neurosurgical, microsurgical, and operative techniques. Practice on simulation models like cadavers has been a trend since antiquity; however, recent development of newer models with their strategic modifications has given simulation education a new dimension. It has allowed trainees to acquire and improve surgical skills and knowledge in specifically fabricated and controlled settings with no risk to real patients. Simulation also offers the opportunity for deliberate practice and repetition unlimited number of times so that psychomotor skills can be automated. There is ever-growing evidence showing the positive impact of simulation on resident training in various areas of health care. Advances in computer technology and imaging, development of sophisticated virtual reality simulators with haptic feedback and the recent addition of three-dimensional printing technology, have opened a wide arena for the development of high-fidelity patient-specific models to complement current neurosurgical training. Simulation training in neurosurgery in India is still elementary since its inception at the All India Institute of Medical Sciences, New Delhi. A structured modular training program has been developed which is yet to be implemented at a multi-institutional level. Stringent efforts are needed to establish a uniform resident training curriculum where simulators can be used to complement current neurosurgical training.

Virtual Planning and Augmented Reality-Guided Microsurgical Resection of a Frontal Arteriovenous Malformation.

Arteriovenous malformations (AVMs) are complex vascular lesions that can pose significant risk for spontaneous hemorrhage, seizures, and symptoms related to ischemia and venous hypertension.1 Microsurgical management of AVMs requires a deep understanding of the surrounding anatomy and precise identification of the lesion characteristics. We demonstrate the use of augmented reality in the localization of arterial feeders and draining veins in relation to bordering normal structures (Video 1). A 66-year-old man presented with several episodes of severe right frontal headaches. Magnetic resonance imaging revealed an AVM along the right frontal pole. Subsequent computed tomography angiography demonstrated arterial supply from the right anterior cerebral artery with venous drainage to the superior sagittal sinus. Due to the size, noneloquent location, and superficial pattern of venous drainage, the patient elected to proceed with microsurgery. A virtual planning platform was used in preparation for surgery. Augmented reality integrated with neuronavigation was used during microsurgical resection. Postoperative angiography showed complete resection of the AVM. The patient was discharged home on postoperative day 3 with no complications. He remains neurologically well at 4 months of follow-up.

Microsurgical Treatment of Pineal Tumors: Anatomy and Techniques.

Pineal region tumors are challenging lesions in terms of surgical accessibility and removal.1 The complexity is compounded by the infrequency and heterogeneity of pineal neoplasms.2,3 In Video 1, we present the case of a 39-year-old woman who presented with progressive headaches and vision impairment. She underwent microsurgical resection for a pineal parenchymal tumor of intermediate differentiation. We discuss the rationale, risks, and benefits of treatment for this patient, as well as provide a detailed overview of the alternative approaches that may be considered. Additionally, we discuss the unique anatomic considerations for each approach and include a virtual reality-compatible 3-dimensional fly-through to highlight the relationship between the tumor and relevant venous anatomy. The patient tolerated the procedure well with excellent neurologic outcome, and her follow-up imaging showed no evidence of tumor recurrence.

The use of Microsurgical Exploration of the External Carotid Artery for Removal of a Retained Microcatheter After Middle Meningeal Artery Embolization Using Live Fluoroscopy: A Technical Note.

BACKGROUND: Fragmentation, disconnection, or entrapment of an in-use microcatheter during neuro-endovascular procedures is a known risk. Often a benign entity, retained catheters are not infrequently observed, but severe complications including thrombus, thromboembolic events, pseudoaneurysm, and limb ischemia have been described, necessitating retrieval. This technical case report demonstrates the safe use of an external carotid artery (ECA) approach for ligation and removal of a retained microcatheter after middle meningeal artery (MMA) embolization. This article also demonstrates the use of live intraoperative fluoroscopy as a surgical adjunct to ensure that the catheter is fully removed without any injury, shearing, or breakage during removal. METHODS: A 66-year-old male patient presented with bilateral subdural hematomas to an outside hospital. He subsequently underwent evacuation of the hematomas followed by a right-sided MMA embolization, complicated by Onyx (Medtronic, Minneapolis, MN) entrapment of the microcatheter in the MMA. The patient was asymptomatic, but there was significant concern about continuing antiplatelet/anticoagulation therapy in the presence of the subdural hematoma. We proceeded with an open surgical approach for catheter retrieval. As the catheter was withdrawn, intraoperative fluoroscopy demonstrated complete removal without any retained fragments. RESULTS: The patient recovered without event and was discharged on postoperative day 1. On follow-up the patient continued to do well without any complications from the fragment that remained in the external carotid circulation. CONCLUSIONS: This case and accompanying video demonstrates the effective use of open ECA surgical approach to retrieve the retained microcatheter after an MMA embolization. This approach allowed for safe and effective removal of the microcatheter while significantly reducing complication risks.