Relationship between the posterior septal artery and the upper edge of the choana.

BACKGROUND: The pedicled nasoseptal flap has been a key element in advancing the endoscopic transnasal approach (ETA) for the treatment of skull base lesions from the anterior cranial fossa to the occipitocervical junction. To preserve vascular supply, an anatomical knowledge of the location of the posterior septal artery (PSA) is essential. The objective of this work is to establish the relationship between PSA and the superior edge of the choana to define a safety margin during the opening of the sphenoidal rostrum preserving PSA. METHODS: One hundred and eighty angiotomographies of the brain were assessed. The sphenopalatine artery (SPA) was evaluated in the pterygopalatine fossa and PSA at its entrance into the nasal cavity and on the sphenoidal rostrum. RESULTS: PSA was found in all 3 tomographic planes (axial, coronal and sagittal) in 100 patients (200 PSAs). Thirty-five were male and 65 were females. Average age was 62 years with a range of 19-90 years. Total average distance between PSA and the superior edge of the choana was 8.5 mm with a range of 2.5-18 (12.45 90th percentile). CONCLUSION: Although the distance between the choanal edge and PSA is 8.5 mm on average, due to its variability, a distance of at least 12.45 mm for the opening of the sphenoidal sinus in the ETA approach should be considered as a safety margin.

Surgical Indication Optimization of Brain Metastases Based on the Evolutionary Analysis of Karnofsky Performance Status.

BACKGROUND AND OBJECTIVE: Surgical resection of brain metastases (BM) offers the highest rates of local control and survival; however, it is reserved for patients with good functional status. In particular, the presence of BM tends to oversize the detriment of the overall functional status, causing neurologic deterioration, potentially reversible following symptomatic pharmacological treatment. Thus, a timely indication of surgical resection may be dismissed. We propose to identify and quantify these variations in the functional status of patients with symptomatic BM to optimize the indication of surgical resection. PATIENTS AND METHODS: Historic, retrospective cohort analysis of adult patients undergoing BM microsurgical resection, consecutively from January 2012 to May 2016, was conducted. The Karnofsky performance status (KPS) variation was recorded according to the symptomatic evolution of each patient at specific moments of the diagnostic-therapeutic algorithm. Finally, survival curves were delineated for the main identified factors. RESULTS: One hundred and nineteen resection surgeries were performed. The median overall survival was 243 days, while on average it was 305.7 (95% confidence interval [CI]: 250.6-360.9) days. The indication of surgical resection of 10% of the symptomatic patients in our series (7.5% of overall) could have been initially rejected due to pharmacologically reversible neurologic impairment. Survival curves showed statistically significant differences when KPS was stratified following pharmacological symptomatic treatment (p < 0.0001), unlike when they were estimated at the time of BM diagnosis (p = 0.1128). CONCLUSION: The preoperative determination of the functional status by KPS as an evolutive parameter after the nononcologic symptomatic pharmacological treatment allowed us to optimize the surgical indication of patients with symptomatic BM.

Extensive Periprosthetic Metallosis Associated to Osteolysis and Spinal Instrumentation Failure: Case Report and Literature Review.

STUDY DESIGN: Case-report and literature review. OBJECTIVE: To depict main features of a potentially deleterious postoperative spinal fixation complication. SUMMARY OF BACKGROUND DATA: Tisular deposit of metal particles from prosthetic systems-metallosis-is an uncommon complication of spinal fixation surgery. Manifestations as chronic postoperative pain, instrumentation failure, infection, or neurological impairment can be developed, but metallosis often appears as an unexpected intraoperative finding. METHODS: A 70-year-old female underwent several spinal fixation procedures due to progressive degenerative adult scoliosis, who developed instrumentation failure. Unexpected metallosis was evidenced extensively surrounding the dislodged construct due to vertebral osteolysis. Instrumentation replacement and debridement of metallotic tissue was performed. We also conduct a literature review for the terms "spinal metallosis" and "spinal corrosion" on the PubMed/MEDLINE database. Previous publications depicting black/dark staining, discoloration and/or fibrotic tissue, as well as histopathological metal particle deposits, or merely metallosis, were reviewed. Articles reporting individual cases or case-series/cohorts with patient-discriminated findings were included. RESULTS: The histopathological analysis of our patient revealed dense fibroconnective tissue with black metallic pigment associated. She evolved with great pain relief in the immediately postoperative period. The patient achieved pain-free standing with significant pharmacotherapy reduction and independent ambulation. The literature search retrieved 26 articles for "spinal metallosis" and 116 for "spinal corrosion"; 16 articles met selection criteria. Approximately 60% of the reported cases accounted for patients younger than 30 years old, mainly related to expandable fixation system (65%) for idiopathic scoliosis. Usually, the symptoms were correlated with abnormal radiological findings: instrumentation breakage, dislodgement, loosening, expandable systems fracture. All the reviewed patients evolved free of pain and neurologically recovered. CONCLUSION: Instrumentation removal and metallosis debridement seems to be useful for symptomatic patients, but remains controversial on fixed asymptomatic patients. If solid fusion has not been achieved, extension, and reinforcement of the failed fixation could be required.Level of Evidence: 4.

A Classification for the Anterior Inferior Cerebellar Artery-Subarcuate Artery Complex Based on the Embryological Development.

Objective To hierarchize the anterior inferior cerebellar artery (AICA)-subarcuate artery (SAA) complex's variations in the surgical field. Background The AICA's "subarcuate loop" (SL) presents multiple variations, closely related to the SAA. AICA-SAA complex's variations may represent major issues in cerebellopontine angle (CPA) surgery. As the spectrum of configurations is originated during the development, a systematized classification was proposed based on the interaction between the petrosal bone and the AICA in the embryonic period. Methods The variations were defined as follow: Grade 0: free, purely cisternal AICA, unidentifiable or absent SAA; Grade 1: purely cisternal AICA, loose SL, SAA > 3 mm; Grade 2: AICA near the subarcuate fossa, pronounced SL, SAA <3 mm; Grade 3: "duralized" AICA, unidentifiable SAA, or included in the petromastoid canal (PMC); and Grade 4: intraosseous AICA, unidentifiable SAA, or included in the PMC. The classification was applied to a series of patients assessed by magnetic resonance constructive interference in steady state sequence. Surgical examples were also provided. Results Eighty-four patients were evaluated, including 161 CPA. The proportions found in the gradation remained within the range of previous publications (Grade 0: 42.2%; Grade 1: 11.2%; Grade 2: 35.4%; Grade 3: 10.6%; and Grade 4: 0.6%). Moreover, the degrees of the classification were related to the complexity of the anatomical relationships and, therefore, to the difficulty of the maneuvers required to overcome them. Conclusion The proposed AICA-SAA complex classification allowed to distinguish and objectify pre- and intraoperatively the spectrum of variations, to thoroughly plan the required actions and instrumentation.

Programa de Simulación Neuroquirúrgica / Neurosurgical Simulation Program

Objetivo: Describir un programa de entrenamiento básico para implementar en la residencia de Neurocirugía con una metodología estructurada, diferentes niveles de complejidad y elementos de fácil adquisición. Introducción: La simulación se define como el uso de modelos para imitar experiencias de la vida real. Debido a la complejidad del aprendizaje en Neurocirugía, el programa de la Residencia debería incluir entrenamiento básico mediante simulación que permita al residente entrenarse en habilidades básicas fuera del quirófano, o bien, desarrollar y complejizar las ya aprendidas. Materiales y Métodos: Se realizó un programa de entrenamiento básico a desarrollar en el Centro de Simulación Quirúrgica del Hospital italiano, dividido en tres niveles de complejidad quirúrgica. Se idearon distintos ejercicios con materiales accesibles, de bajo costo y replicables. El programa se diseñó para ser llevarse a cabo con una frecuencia de una vez por semana durante cinco horas. Discusión: Los modelos propuestos presentan fácil acceso y alta disponibilidad; y permitieron el desarrollo de habilidades microquirúrgicas desde etapas muy tempranas de la residencia, abarcando la utilización del instrumental microquirúrgico y la magnificación microscópica, y simulando distintas técnicas quirúrgicas en materiales biológicos y sintéticos realistas; enmarcado por un programa basado en objetivos sin límites de repeticiones. La evaluación con un neurocirujano Senior permitió brindar un espacio relajado de enseñanza y debate, sin ser influenciado por las presiones propias de la cirugía. El aprendizaje de técnicas quirúrgicas se basa en la repetición de maniobras específicas, por lo que el desarrollo de habilidades quirúrgicas en ámbitos académicos no asistenciales es fundamental en cualquier aprendizaje quirúrgico. Conclusión: La simulación en el entrenamiento neuroquirúrgico sigue siendo un campo de estudio que requiere mayor investigación y validación en su implementación. En nuestra experiencia resulta una herramienta sumamente favorable para su posterior aplicación en procedimientos quirúrgicos reales, que podría mejorar y homogeneizar la enseñanza en programas de formación quirúrgica

Objective: To describe a basic training program to implement at neurosurgery residency with a structured methodology, different complexity levels, and easily acquired elements. Introduction: Simulation is defined as use of models to imitate real life experiences. Due to complexity of neurosurgery learning, residency program should include simulation training that allows the resident learning basic skills outside the operating room and develop practices learned. Materials and methods: A training program was developed at Centro de Simulación Quirúrgica del Hospital Italiano, divided into three surgical complexity levels. Different exercises were designed with accessible, low cost and replicable materials. This program is carried out with a frequency of once a week, five hours each. Discussion: The proposed models have easy acquisition and high availability, allowing the development of microsurgical skills since early stages in residency, including the use of microsurgical instruments and microscopic magnification, surgical techniques in realistic biological and synthetic materials, based on a program with objectives without repetition limits. The evaluation with a senior neurosurgeon allowed providing a relaxed teaching space, without pressures of surgery. Learning of surgical techniques is based on repetition, so the development of surgical skills in non-assistance academic fields is fundamental in any surgical learning. Conclusion: Simulation in neurosurgical training remains a field that requires further investigation and validation in its implementation. In our experience, it is an extremely favorable tool because its subsequent application in real life procedures, which could improve and standardize surgical programs teaching

Effect of oxidized cellulose on human respiratory mucosa and submucosa and its implications for endoscopic skull-base approaches.

BACKGROUND: Regenerated oxidized cellulose (ROC) sheets have gained popularity as an adjunct to a vascularized nasoseptal flap for closure of dural defects after endoscopic endonasal skull-base approaches (EESBS). However, evidence supporting its impact on the healing process is uncertain. This study was performed to evaluate the impact of ROC on the nasal mucosa and assess its effects on tissue pH, structure, and cell viability. METHODS: In 5 patients, a 1-cm2 piece of ROC gauze was placed on the surface of the middle turbinate before it was resected as part of a standard EESBS. Mucosa treated with ROC was separated from untreated mucosa and a histologic examination of structural changes in the respiratory epithelium was performed. To assess the effect of ROC on pH, increasing amounts of ROC were added to culture medium. Nasal fibroblasts viability was assessed in the presence of ROC before and after the pH was neutralized. RESULTS: Compared with unexposed controls, treated mucosa exhibited a higher incidence of cell necrosis and epithelial cell detachment. When added to Dulbecco's modified Eagle medium, ROC caused a dose-dependent decrease in pH of the medium. Only 1 ± 0.8% of cultured fibroblasts exposed to the ROC-induced acidic medium were alive, whereas 98.25 ± 0.5% of the cells were viable when the pH was neutralized (p < 0.001). CONCLUSION: ROC applied in vivo to nasal mucosa induced epithelial necrosis likely by diminishing the medium pH, because pH neutralization prevents its effect. The ultimate effect of this material on the healing process is yet to be determined.

RODEXKE. Infiltración con ropivacaína, dexmedetomidina y ketorolac en cirugía espinal: Una estrategia para disminuir el consumo de opioides / RODEXKE. Infiltration with ropivacaine, dexmedetomidine, and ketorolac in spinal surgery: A strategy to decrease opioid consumption

Objetivos: Evaluar la efectividad de la infiltración del sitio quirúrgico, con ropivacaína, dexmedetomidina y ketorolac, en pacientes sometidos a instrumentación transpedicular dorsolumbar con técnica mini invasiva, en cuanto al consumo de opioides durante la internación. Materiales y métodos: Se recolectaron en forma retrospectiva los datos prospectivos de las historias clínicas de pacientes con una instrumentación con tornillos transpediculares percutáneos operados entre Junio del 2016 y Diciembre del 2018. 32 pacientes cumplieron con los criterios de selección. Se infiltró en el momento del cierre quirúrgico con una solución preparada con 150 mg de ropivacaína, 0,7 mcg/kg de dexmedetomidina y 60 mg de ketorolac, disuelto en solución fisiológica estéril para completar 40ml (Grupo M) y se la comparó con pacientes en los cuales solo se infiltró con 150mg de ropivacaína (Grupo E). Resultados: El consumo de equivalentes de morfina durante las primeras 72hs postoperatorias presentó en el grupo M una mediana de 0mg, y el grupo E, una mediana de 9,5mg (RIQ de 13,35), con una p<0,000. Por el contrario el consumo de morfina en la sala de recuperación presentó una mediana de 0mg (RIQ de 2) para el grupo M, y de 2mg (RIQ de 5) para el grupo E, sin encontrarse una diferencia significativa, p=0,132. Conclusión: Los resultados obtenidos en la comparación del consumo de opioides durante las primeras 72hs de la internación permite inferir que esta combinación de fármacos es superior respecto a la infiltración estándar con ropivacaína, independientemente de la estrategia analgésica utilizada durante el tiempo quirúrgico.

Objectives: To assess the effectiveness of a surgical site infiltration with ropivacaine, dexmedetomidine and ketorolac, in reducing opioid consumption in patients with a transpedicular dorsolumbar instrumentation using a minimally invasive technique. Materials y methods: We retrospectively collected data from patient's charts from June of 2016 to December of 2018. 32 patients with minimally invasive transpedicular dorsolumbar instrumentation, who met all criteria, were included in the analysis. During wound closure a mixture of 150mg of ropivacaine, 0,7mcg/kg of dexmedetomidine and 60mg of ketorolac, diluted in normal saline to achieve 40ml was injected (Group M). We compared them with patients in whom only 150mg of ropivacaine and saline where injected in the surgical site (Group E). Results: Morphine equivalents use during the first 72 hours postoperative had a median of 0mg for group M, and of 9,5mg (IQR of 13.35), with a p<0,000. On the contrary, morphine use during post anesthesia care unit stance had a median of 0mg (IQR of 2) for group M and of 2mg (IQR of 5) for group E, without a statistically significant difference, p=0,132. Conclusion: The result of the analysis of opioid consumption during the first 72 hours postoperative allows concluding that the infiltration of these 3 drugs together its superior to the standard infiltration with ropivacaine, independently of the analgesic strategy used during the surgery.

Resección microquirúrgica de meningioma de la región pineal / Microsurgical resection of meningioma of the pineal region

Introducción: Los meningiomas de la región pineal son lesiones poco frecuentes, representando el 2 al 8% de los tumores localizados en esta área. Estos tumores son lesiones con comportamiento biológicamente benigno y potencialmente curables con la resección quirúrgica radical. A su vez representan un desafío quirúrgico debido a su profunda localización y la cercanía de estructuras anatómicas vitales. El abordaje supracerebeloso infratentorial, en posición semisentado (cuando las condiciones generales del paciente lo permiten), provee un corredor natural a la región pineal mediante la retracción cerebelosa gravitatoria. Objetivo: Presentación de la exéresis microquirúrgica completa de un meningioma de la región pineal. Descripción del caso: Paciente de 52 años que consulta por inestabilidad de la marcha y diplopía de 2 semanas de evolución. La resonancia magnética cerebral mostró una lesión expansiva, que realza con contraste, de 43 x 30 mm en la región pineal, con hidrocefalia obstructiva acompañante. Se realiza la exéresis microquirúrgica mediante abordaje supracerebeloso infratentorial con el paciente en posición semisentado. Resultado: Se realizó la exéresis completa de la lesión. La paciente cursó el primer día postoperatorio en Unidad de Terapia Intensiva y luego pasó a sala de internación general. Fue dada de alta al tercer día, sin déficit neurológico. La anatomía patológica de la lesión informó meningioma transicional (OMS grado I). El control imagenológico postquirúrgico mostró la resección de la lesión sin remanente tumoral. Conclusión: Los meningiomas de la región pineal presentan un desafío quirúrgico debido a la relación con estructuras anatómicas vitales. El abordaje supracerebeloso infratentorial ofrece un corredor anatómico natural mediante la retracción cerebelosa por la gravedad.

Background: Meningiomas of the pineal region are rare lesions representing 2 to 8% of the tumors located in this area. These tumors are lesions with biologically benign behavior and potentially curable by radical surgical resection. As well, they are a surgical challenge due to their deep location and the proximity to vital anatomical structures. The supracerebellar infratentorial approach, in a semisitting position (when the patient's general conditions allow it), provides a natural corridor to the pineal region through gravitational cerebellar retraction. Objetive: Presentation of a complete microsurgical resection of a meningioma of the pineal region. Case description: A 52-year-old patient who consulted due to gait instability and diplopia of 2 weeks of evolution. Brain magnetic resonance showed an expansive lesion, with contrast enhancement, 43 x 30 mm in the pineal region, with obstructive hydrocephalus. The microsurgical resection was performed by supracerebellar infratentorial approach with the patient in a semisitting position. Result: The complete microsurgical resection was achieved. The patient spent the first postoperative day in Intensive Care Unit, and then went to general room. He was discharged on the third postoperative day, without neurological deficit. The histopathology assessment of the lesion reported transitional meningioma (WHO grade I). Post-surgical imaging showed the resection of the lesion without remaining tumor. Conclusion: Meningiomas of the pineal region present a surgical challenge due to the relationship with vital anatomical structures. The supracerebellar infratentorial approach offers a natural anatomical corridor through cerebellar retraction by gravity.

[Usefulness of minimally invasive spine surgery for the management of thoracolumbar spinal metastases]. / Utilidad de la cirugía espinal mínimamente invasiva en el manejo de las metástasis espinales toraco-lumbares.

OBJECTIVE: To describe the surgical results and evolution of patients who underwent minimally invasive spine surgery (MISS) for the treatment of thoracolumbar spinal metastases, using the NOMS (Neurological, Oncological, Mechanical, Systemic) assessment for the therapeutic decision. METHODS: Patients who underwent MISS technique for the treatment of thoracolumbar spinal metastases were prospectively enrolled at the Hospital Italiano de Buenos Aires, from June 2014 to June 2017. In all cases, the NOMS assessments were performed for therapeutic decision making. Surgical results were analyzed in terms of improvements in Karnofsky performance status, pain relief (VAS - visual analog scale), Frankel, blood loss, need for transfusions, complications, use of opioids and hospitalization length. A P < 0.05 value was considered statistically significant. RESULTS: During the study period 26 patients were included, 13 of them were women. The average age was 57-year-old (27-83 years). Breast cancer was the most frequent primary tumor (27%). The main symptom was pain (96%), although 12 patients presented with myelopathy (46%). High-grade epidural spinal cord compression requiring decompression was observed in 17 cases (65%). According to the SINS (spinal instability neoplastic score), most lesions were potentially unstable or unstable (89%) requiring MISS stabilization. After surgery, pain relief (VAS) and neurological recovery (Frankel) improved significantly in the 77% and 67% of the cases, respectively, with low intraoperative blood loss and without any transfusions. Only one minor surgical complication was presented (4%). The average of hospital stay was 5.5 days. CONCLUSION: In our series and using the NOMS as a therapeutic algorithm, MISS was effective for decompression and spinal stabilization, with a low rate of complications and rapid postoperative recovery.

[Minimally invasive resection of spinal synovial cysts: Technical note]. / Resección mínimamente invasiva de quistes sinoviales espinales. Nota técnica.

OBJECTIVE: To present the treatment algorithm, surgical technique, and results of a series of patients with spinal synovial cysts operated with minimally invasive techniques (MIS). INTRODUCTION: Spinal synovial cysts originate from the dilation and potential rupture of the synovial sheath of a facet joint. Surgical resection is considered the treatment of choice in symptomatic patients. The use of MIS techniques could reduce the disruption of the facet joint involved, reducing the risk of postoperative instability. MATERIALS AND METHODS: We retrospectively evaluated 21 patients with spinal synovial cysts operated by MIS approach and decompression. We analyzed the signs, symptoms, surgical time, hospital stay, evolution, and complications. The visual analog scale (VAS) was used to evaluate pain and the Weiner scale and the modified Macnab criteria to measure the patient's postoperative satisfaction. RESULTS: A total of 21 patients were surgically treated with MIS technique; 76.2% (n = 16) did not require arthrodesis, the remaining 23.8% (n = 5) were fused. We performed 13 (61.9%) contralateral hemilaminectomies, 7 ipsilateral hemilaminectomies (33.3%), and 1 laminectomy in S1-S2. The average follow-up was 26 months; surgical time was 150.33 ± 63.31 min, with a hospital stay of 2.5 ± 1.78 days. The VAS decreased from 8.3 preoperatively to 2.3 postoperatively. Sixteen patients reported excellent results, four good and one regular in the scale of Macnab. 95.2% of patients perceived that the procedure was very/quite successful according to the Weiner scale. CONCLUSION: The minimally invasive approach is a safe and effective procedure for the complete resection of spinal synovial cysts. It provides excellent clinical-functional results by preserving muscles, ligaments, and joint facets.

Relación entre la arteria septal posterior y el borde superior de la coana / Relationship between the posterior septal artery and the superior border of the choana

Introducción: El colgajo pediculado nasoseptal (CPNS) ha sido un elemento fundamental en el avance del abordaje transnasal endoscópico (TNE) para tratar lesiones de la base de cráneo desde la fosa anterior hasta el clivus y la unión occipitocervical. El CPNS provee un tejido viable, vascularizado, extenso y versátil el cual es capaz de adherirse al hueso y sellar el defecto dural disminuyendo así el riesgo de fístula de líquido cefalorraquídeo (LCR) en el postoperatorio, del más del 20% a menos del 5%. Tanto para el CPNS primario como para colgajo de rescate es necesario preservar el pedículo vascular por lo que es fundamental el conocimiento anatómico de la localización de la arteria septal posterior y sus ramas, así como los reparos anatómicos para reconocerla en el intraoperatorio. Objetivo: Establecer la relación entre la arteria septal posterior (ASP) y el borde superior de la coana para definir un margen de seguridad durante la apertura del rostro esfenoidal preservando la ASP y sus ramas. Material y métodos: Estudio observacional, descriptivo, retrospectivo de corte transversal. Angiotomografía cerebral (ATC) con contraste endovenoso realizadas en pacientes mayores a 18 años de ambos sexos para el estudio de lesiones vasculares intracraneales. Las ATC fueron realizadas en un tomógrafo Aquilion ONE 320 (Toshiba, Japan). Para la visualización y medición de las imágenes se utilizó el software Alma Workstation V4.2.0.2 (Alma IT Systems). Se documentaron las variaciones anatómicas y se realizaron mediciones entre el borde superior de la coana y la arteria septal posterior en ambas fosas nasales (Fig 2 a y b). Resultados: De los 98 pacientes estudiados, 32 eran varones y 66 mujeres. La edad media fue de 62,6 con un rango de 19 a 90 años (Tabla 1). Se realizaron mediciones en ambos lados (196 ASP). La distancia media entre la ASP y el borde superior de la coana fue de 14,8 mm del lado izquierdo y 14,7 mm del lado derecho. La distancia media total fue de 14,82 (Tabla 1, Fig 4). Discusión: El borde superior de la coana es un reparo confiable por su constancia en la práctica quirúrgica. Otros autores han medido la distancia entre la rama superior de la ASP y el ostium esfenoidal en 8.2 ± 0.5 mm con un rango de 6.6 a 12.2 mm. Sin embargo el ostium no es un reparo tan confiable por su variable localización en el rostro esfenoidal. La distancia entre la ASP o su rama inferior y el arco de la coana, está descrita a 6.72 ± 2.64 mm con un rango de 2.34­12.64. Sin especificar entre la ASP o su rama inferior. Conclusión: La ASP se encuentra en promedio a aproximadamente 15 mm cefálico al borde superior de la coana. Esta distancia puede ser considerada como un margen de seguridad para evitar lesionar el pedículo vascular durante la confección del CPNS o bien para preservarlo durante la apertura del rostro esfenoidal en caso de requerirse un CPNS de rescate.

Accuracy in Percutaneous Transpedicular Screws Placement Using Biplane Radioscopy: Systematic Review and Meta-Analysis.

STUDY DESIGN: Systematic review and descriptive data meta-analysis. OBJECTIVE: The objective of this study was to appropriately establish the accuracy in the percutaneous transpedicular screws (PTS) placement using biplane radioscopy (Rx-2D). SUMMARY OF BACKGROUND DATA: The Rx-2D is a widely-used technique for PTS as it is practical, ubiquitous, and cost-effective. However, the reported "acceptable" accuracy attained by this method is widely variable ranging between 76% and 100%. METHODS: A systematic review was conducted to screen publications about PTS placement using Rx-2D guidance. PubMed/MEDLINE database was consulted using the search term "percutaneous pedicle screw" from 1977 to 2017. Previous meta-analysis and reference lists of the selected articles were reviewed. Accuracy values were assessed fulfilling the proposed criteria. Observational data meta-analysis was performed. Cochran's Q test was used to determine heterogeneity among data extracted from the series, which was quantified by I test. P-values≤0.05 were considered statistically significant. The results were depicted by Forest plots. Funnel plots were outlined to visualize a possible bias of publication among the selected articles. RESULTS: In total, 27 articles were included in the analysis. Results of the accuracy were as follow, 91.5% (n=7993; 95% CI, 89.3%-93.6%) of the screws were placed purely intrapedicular, and 96.1% (n=8579; 95% CI, 94.0%-98.2%) when deviation from the pedicle was up to 2 mm. CONCLUSIONS: This meta-analysis is the largest review of PTS placed with Rx-2D guidance reported up to date. We concluded that the procedure is a safe and reproducible technique. The key values obtained in this work set reliable references for both clinical and training outcome assessing.

Una propuesta de clasificación del complejo arteria cerebelosa anteroinferior ­ arteria subarcuata basada en el desarrollo embriológico / A proposed classification of the anteroinferior cerebellar artery - subarcuate artery complex based on embryological development

Introducción: El recorrido del "loop subarcuato" de la arteria cerebelosa anteroinferior (ACAI) presenta múltiples variaciones que condicionan además su principal eferencia, la arteria subarcuata (ASA). El espectro de variaciones de este complejo ha sido referido en la literatura de forma inconexa y desorganizada. Material y Métodos: Se propuso una clasificación sistematizada de las variantes del complejo ACAI-ASA, basada en la interacción del hueso petroso y la ACAI en el periodo embrionario. La misma fue aplicada en una serie de pacientes estudiados mediante secuencia CISS (constructive interference in steady state) de resonancia magnética para categorizar las relaciones presentes en el ángulo pontocerebeloso (APC). Resultados: Se evaluaron 84 pacientes, incluyendo 161 APC. Todos los grados propuestos fueron identificados en la serie evaluada. Las proporciones encontradas en la gradación propuesta se mantuvieron en el rango de las publicaciones aisladas. Conclusión: La clasificación propuesta para el complejo ACAI-ASA permitió distinguir y objetivar consistentemente el espectro de variaciones.

Introduction: The pathway of the anterior inferior cerebellar artery's (AICA) "subarcuate loop" can vary extensively. This variability also affects its main branch, the subarcuate artery (SAA). The spectrum of variations observed with this combination of vessels is inadequately described in the literature. Methods and Materials: A systematized classification system for AICA-SAA complex variants was proposed, based upon interactions between the petrosal bone and the AICA in embryos. This classification scheme then was applied to a series of patients assessed by magnetic resonance CISS (constructive interference in steady state) sequences, to categorize the cerebellopontine angle (CPA) relationships. Results: Eighty-four patients were evaluated, encompassing 161 CPA. All the proposed grades were identified in the evaluated series. The proportions found with the proposed gradation system were within the range of previous publications. Conclusions: The AICA-SAA complex classification system that we proposed allowed for consistently distinguishing and objectifying the spectrum of variations seen in the subarcuate loop.

Resección Mínimamente Invasiva de Quistes Sinoviales Espinales. Nota Técnica / Minimally Invasive Resection of Spinal Synovial Cysts. Technical note

Objetivo: Presentar el algoritmo de tratamiento, técnica quirúrgica y resultados de una serie de pacientes con quistes sinoviales espinales resecados con técnica mínimamente invasiva (MIS). Introducción: Los quistes sinoviales espinales se originan a partir de la dilatación y potencial ruptura de la vaina sinovial de una articulación facetaria. La resección quirúrgica es considerada el tratamiento de elección en pacientes sintomáticos. La utilización de técnicas MIS podrían disminuir la disrupción de la faceta articular comprometida reduciendo el riesgo de inestabilidad postoperatoria. Material y métodos: Se evaluaron retrospectivamente 21 pacientes con quistes sinoviales espinales operados mediante abordaje y descompresión MIS, se analizaron los signos, síntomas, tiempo quirúrgico, estadía hospitalaria, evolución y complicaciones. Se utilizó la escala visual analógica (EVA), para evaluar el dolor y la escala de Weiner y los criterios de Macnab modificados para medir la satisfacción posoperatoria del paciente. Resultados: Se trataron quirúrgicamente 21 pacientes (13 mujeres, 8 hombres), el 76,2% (n=16) de los pacientes de la serie no requirió artrodesis, el 23,8% (n=5) restante fue fusionado. Realizamos 13 (61,9%) hemilaminectomías contralaterales, 7 hemilaminectomías ipsilaterales (33,3%) y una laminectomía en el QS S1-S2 con técnica MIS. El seguimiento promedio fue de 26 meses, el tiempo de cirugía fue de 150,33 ± 63,31 min., con una estadía hospitalaria de 2,5 ± 1,78 días. La EVA disminuyó de 8,3 preoperatoria a 2,3 postoperatoria. Siguiendo la escala de Macnab; 16 pacientes refirieron resultados excelentes, 4 buenos y 1 regular, el 95,2% de los pacientes percibió que el procedimiento tuvo mucho/bastante éxito según la escala de Weiner. Conclusión: El abordaje mínimamente invasivo es un procedimiento seguro y eficaz para la resección completa de quistes sinoviales espinales. Proporciona resultados clínico-funcionales excelentes preservando músculos, ligamentos y facetas articulares.

Introduction: Spinal synovial cysts originate from the dilation and potential rupture of a facet joint's synovial sheath. Surgical resection is considered the treatment of choice in symptomatic patients; however, the use of minimally-invasive surgery (MIS) techniques could reduce any disruption of the facet joint involved, reducing the risk of postoperative instability. Objective: To present the treatment algorithm, surgical technique and results in a series of patients with spinal synovial cysts treated by MIS. Methods and Materials: We retrospectively evaluated 21 patients with spinal synovial cysts who underwent therapeutic MIS with decompression. Signs, symptoms, surgical time, hospital stay, course and complications were evaluated. A visual analog scale (VAS) was used to rate pain, while the Weiner scale and modified Macnab criteria were employed to measure patients' postoperative satisfaction. Results: Twenty-one patients were surgically treated with MIS, among whom 76.2% (n = 16) required no arthrodesis; the remaining 23.8% (n = 5) were fused. We performed 13 (61.9%) contralateral hemilaminectomies, seven ipsilateral hemilaminectomies (33.3%), and one laminectomy at S1-S2. The average follow-up was 26 months, surgical time 150.33 ± 63.31 minutes, and mean hospital stay 2.5 ± 1.8 days. The VAS pain rating decreased from 8.3 preoperatively to 2.3 postoperatively. Sixteen patients reported excellent results, four good and one fair. On the Macnab scale, all but one patient (1/21, 4.8%) perceived that the procedure had been very/quite successful. Conclusions: Minimally-invasive surgery is a safe and effective approach for the complete resection of spinal synovial cysts. It provides excellent clinical and functional results, by preserving muscles, ligaments and facet joints.

[Optical coherence tomography as a predictor of visual recovery in patients with pituitary macroadenomas]. / Tomografía de coherencia óptica como predictor de recuperación visual en pacientes con macroadenomas hipofisarios.

BACKGROUND: With pituitary macroadenomas, there is a high incidence of visual loss from optic pathway compression. Surgical removal of the tumor usually prevents progression and allows visual recovery. Our objective was to evaluate if optical coherence tomography (OCT) predicts visual outcomes after surgical decompression. METHODS: Patients with pituitary macroadenomas were prospectively recruited between February 2015 and November 2016. We evaluated preoperative and postoperative visual acuity, automated perimetry, and OCT. We compared the results 6-12 weeks and 6-9 months after surgical removal of the tumor. Dependent and independent continuous variables were analyzed by Student's t-test, linear regression analysis, and Pearson's correlation coefficients, considering P < 0.05 as statistically significant. RESULTS: Visual acuity and visual field defects were much worse in patients with a thin preoperative retinal nerve fiber layer (RNFL). Both patients with normal RNFL thickness and patients with thin RNFL experienced significant improvement in postoperative visual perimetry 6-12 weeks after surgery. OCT values correlated inversely with pre- and postoperative visual fields, which means that, if the nerve was thicker, the visual field was better. Patients with a normal OCT had greater recovery because their preoperative perimetry values were better. The correlation between OCT values and visual field improvement was weak, suggesting that patients' visual fields improved after decompressive surgery independent of the nerve's thickness. CONCLUSION: The computerized visual field continues to be the gold standard in the evaluation of patients with pituitary macroadenomas with optic pathway compression. Our results suggest that OCT might not be an accurate predictor of visual outcomes.

[Drilling of the subarcuate fossa to release the anterior inferior cerebellar artery in a surgery of a vestibular Schwannoma]. / Fresado de la fosa subarcuata para liberar la arteria cerebelosa anteroinferior en una cirugía de un Schwannoma vestibular.

INTRODUCTION: A retrosigmoid suboccipital approach is the route most commonly utilized to resect vestibular schwannomas (VS). However, the anterior inferior cerebellar artery (AICA) usually runs adjacent to internal auditory canal nerves, and its course may severely impede total tumor resection. CASE REPORT: A 38-year-old male patient presented with presumed grade T3B VS, diagnosed by magnetic resonance imaging (MRI). Surgery was performed using a retrosigmoid approach, during which the AICA was identified to be completely covered by dural and bone tissue. Further drilling in the subarcuate fossa was necessary to release the AICI, allowing for total gross resection of the VS. No neurological deficits were observed postoperatively. DISCUSSION: On rare occasions, the AICA has been described fixed to the dura and/or embedded within subarcuate fossal bone, thereby preventing removal of the intra-canalicular portion of the VS and, hence, total resection. However, AICA release adds to the risk of vascular injury. CONCLUSION: Injury to the AICA may cause high morbidity in patients with a VS. Neurosurgeons must be able to recognize and deal with certain anatomical configurations that place patients at particularly high risk.

Differential response of pineal microglia to surgical versus pharmacological stimuli.

Microglial cells are one of the interstitial elements of the pineal gland (PG). We recently reported the pattern of microglia colonization and activation, and microglia-Pax6+ cell interactions during normal pineal ontogeny. Here, we describe the dynamics of microglia-Pax6+ cell associations and interactions after surgical or pharmacological manipulation. In adult rats, the superior cervical ganglia (SCG) were exposed, and either bilaterally excised (SCGx) or decentralized (SCGd). In the SCGx PGs, the density of Iba1+ microglia increased after surgery and returned to sham baseline levels 13 days later. Pineal microglia also responded to SCGd, a more subtle denervation. The number of clustered Iba1+ /PCNA+ /ED1+ microglia was higher 4 days after both surgeries compared to the sham-operated group. However, the number of Pax6+ /PCNA- cells and the percentage of Pax6+ cells contacted by and/or phagocytosed by microglia increased significantly only after SCGx. Separate groups of rats were treated with either bacterial lipopolysaccharides (LPS) or doxycycline (DOX) to activate or inhibit pineal microglia, respectively. Peripheral LPS administration caused an increase in the number of clustered Iba1+ /PCNA+ /ED1+ microglial cells, and in the percentage of Pax6+ cells associated with and/or engulfed by microglia. In the LPS-treated PGs, we also noted an increase in the number of PCNA+ cells that were Iba1- within the microglial cell clusters. The density of Pax6+ cells did not change after LPS treatment. DOX administration did not influence the parameters analyzed. These data suggest that pineal microglia are highly receptive cells capable of rapidly responding in a differential manner to surgical and pharmacological stimuli.

Utilidad de la cirugía espinal mínimamente invasiva (MISS) en el manejo de las metástasis espinales toraco-lumbares / Utility of minimally invasive spinal surgery (MISS) in the management of thoraco-lumbar spinal metastases

Objetivo: Describir los resultados quirúrgicos y evolución de pacientes con metástasis espinales toraco-lumbares operadas con técnica mínimamente invasiva (MISS) utilizando para la decisión terapéutica la evaluación: Neurológica, Oncológica, Mecánica y Sistémica (NOMS). Material y Métodos: Se incluyeron en forma prospectiva pacientes con metástasis espinales toraco-lumbares operados con técnica MISS por el Servicio de Neurocirugía del Hospital Italiano de Buenos Aires, entre junio de 2014 y junio de 2017. Se utilizó en todos los casos el algoritmo de evaluación NOMS para la decisión terapéutica. Se analizaron los resultados quirúrgicos postoperatorios como el Karnofsky Performance Status (KPS), dolor (VAS: Visual Analogue Scale), Frankel, pérdida sanguínea, necesidad de transfusiones, complicaciones, uso de opioides y días de internación. Se consideró como estadísticamente significativo una p<0,05. Resultados: Durante el período de estudio 26 pacientes cumplieron los criterios de inclusión, de los cuales 13 fueron mujeres. La edad promedio fue 57 (27-83) años. El origen más frecuente de las lesiones fue cáncer de mama (27%). El síntoma más constante fue el dolor (96%), aunque 12 pacientes manifestaron inicialmente mielopatía (46%). Se observaron grados avanzados de invasión del canal con requerimiento de descompresión en el 65% de los casos. Acorde al Spinal Instability Neoplastic Score (SINS), 23 pacientes (89%) presentaron lesiones potencialmente inestables o inestables, requiriendo estabilización. Se evidenció una mejoría estadísticamente significativa del VAS en el 77% y del Frankel en el 67% de los casos tras la cirugía. No hubo necesidad de transfusiones. Se registró sólo una complicación quirúrgica leve (4%). La media de internación fue de 5,5 días. Conclusión: En nuestra serie y utilizando como algoritmo terapéutico el NOMS, la cirugía MISS resultó efectiva tanto para la descompresión para la estabilización espinal, con baja tasa de complicaciones y rápida recuperación postoperatoria.

Objective: To describe the surgical results and evolution of patients who undergo minimally-invasive spinal surgery (MISS) to treat thoracolumbar metastases, using the NOMS (Neurological, Oncological, Mechanical, Systemic) assessment tool to aid therapeutic decisions. Methods: Patients who underwent MISS to treat thoracolumbar metastases were prospectively enrolled at the Hospital Italiano de Buenos Aires, from June 2014 to June 2017. In all cases, the NOMS assessment tool was employed for therapeutic decision-making. Surgical results were analyzed, in terms of improvements in Karnofsky Performance Status (KPS), pain severity (VAS), and the Frankel neurological scale; also measured were blood loss and the need for transfusions, complications, use of opioids, and the length of hospitalization. P values <0.05 were considered statistically significant. Results: Twenty-six patients were enrolled (13 women) of mean age 57 years old (27-83). Breast cancer was the most frequent primary tumor (27%). The main presenting symptom was pain (96%), although 12 patients presented with myelopathy (46%). High-grade epidural spinal cord compression requiring decompression was observed in 17 patients (65%). According to the SINS (Spinal Instability Neoplastic Score), most lesions were either potentially unstable or unstable (89%), requiring stabilization. After surgery, pain severity and neurological status improved significantly in 77% and 67% of patients, respectively, with low intraoperative blood loss and no need for transfusions. Only one minor surgical complication occurred (4%). The average hospital stay was 5.5 days. Conclusion: In our series, using the NOMS instrument as the therapeutic algorithm, MISS was effective for spinal decompression and stabilization, with a low rate of complications and rapid postoperative recovery.

Application of Fibrin Rich in Leukocytes and Platelets in the Reconstruction of Endoscopic Approaches to the Skull Base.

BACKGROUND: The objective of this work is to report the feasibility and results of an institutional protocol for the application of an innovative biologically active hemoderivative autologous material, denominated leukocyte- and platelet-rich fibrin (L-PRF), in the reconstruction of endoscopic approaches to the sellar region. METHODS: L-PRF membranes were produced from centrifuged autologous venous blood. They were used for the reconstruction of transsphenoidal endoscopic approaches to the sellar region in 12 patients. The trophism of the mucosa was monitored during the first 30 days by means of fiberoptic endoscopic controls on the second and seventh postoperative days. Follow-up was performed to rule out complications up to 30 postoperatively days. RESULTS: The product obtained bore the characteristics of the original descriptions of L-PRF. Standardized preparation of L-PRF membranes promoted early regeneration of the sphenoid sinus mucosa to close endoscopic approaches to the sellar region. No complications within the first 30 postsurgical days were reported. CONCLUSIONS: L-PRF membranes offer characteristics that are superior to other techniques and products, mainly because of their role as biological promoters of tissue regeneration, their low economic cost, and immediate availability. However, it would be necessary to confirm these results in studies involving more patients.

[Learning curve of minimally invasive pedicle screw placement]. / Curva de aprendizaje en la colocación de tornillos pediculares percutáneos mínimamente invasivos.

OBJECTIVE: The aim of this study was to estimate the learning curve needed for correct placement of minimally invasive percutaneous pedicle screws (PPS). INTRODUCTION: PPS are the most common system used for instrumentation of spinal lesions that require stabilization. METHODS: We retrospectively assessed the insertion of 422 PPS (T5 to S1) in 75 patients operated between 2013-2016 under two-dimensional fluoroscopic guidance. The surgeon 1 always placed the PPS on the right side and the surgeon 2 on the left side. Screw positioning and pedicle rupture was determined with the Gertzbein tomographic classification. We compared the accuracy of PPS placement in our series with a reference rupture rate of 8.08%, value obtained from a meta-analysis. RESULTS: Of the 422 TTP, 395 were inserted into the pedicle without violation of its cortical wall (Grade 1 = 93.6%), 27 (6.4%) disrupted the pedicle, of which 3.8% were Grade 2, 1.65% Grade 3 and only 0.9% Grade 4. The Surgeon 1, presented an overall break rate of 6.6% reaching standard values of accuracy by placing 74 PPS, Surgeon 2 showed a disruption rate of 6.1%, reaching baseline values at 64 PPS; the difference between them was not statistically significant (P = 0.9009). CONCLUSION: In our series, it was necessary to place approximately 70 PPS to achieve intrapedicular accuracy comparable to results reported by experienced surgeons in this minimally invasive technique.