Two-Stage Pulsatile Human Placenta Model for Microvascular Anastomosis Training in Neurosurgery.

OBJECTIVE: The development of microsurgical skills is crucial for neurosurgical education. The human placenta is a promising model for practicing vascular anastomosis due to its similarities with brain vessels. We propose a 2-stage model for training in extracranial-to-intracranial anastomosis using the placenta. METHODS: Initially, we propose practicing anastomosis in 2 adjacent placentas. Once successful, the procedure advances to a more challenging configuration that employs a 3-dimensionally printed skull with a window simulating a pterional craniotomy. It is positioned an intracranial placenta and an extracranial one, and the latter has a prominent vessel exposed toward the side of the craniotomy. Both placentas have one artery and vein cannulated in the umbilical cord, and we present an artificial placental circulation system for microvascular training that regulates pulsation and hydrodynamic pressure while keeping veins engorged with a pressurized bag. To verify anastomosis patency, we utilize sodium fluorescein and iodine contrast. RESULTS: The 2-stage model simulated several aspects of microvascular anastomosis. Our perfusion system allowed for intraoperative adjustments of hydrodynamic pressure and pulsation. Using iodine contrast and fluorescein enabled proper evaluation of anastomosis patency and hydrodynamic features. CONCLUSIONS: Training in the laboratory is essential for developing microsurgical skills. We have presented a model for microvascular anastomosis with artificial circulation and postoperative imaging evaluation, which is highly beneficial for enhancing the learning curve in microvascular procedures.

The role of the Liliequist membrane in the third ventriculostomy.

Endoscopic third ventriculostomy (ETV) is a hydrocephalus treatment procedure that involves opening the Liliequist membrane (LM). However, LM anatomy has not been well-studied neuroendoscopically, because approach angles differ between descriptive and microsurgical anatomical explorations. Discrepancies in ETV efficacy, especially among children age 2 and younger, may be due to incomplete LM opening. The objective of this study was to characterize the LM anatomically from a neuroendoscopic perspective to better understand the impact of anatomical features during LM ostomy and the ETV success rate. Additionally, the ETV success score was tested to predict patient outcome after the intraoperatively difficult opening of LM. Fifty-four patients who underwent ETV were prospectively analyzed with a mean follow-up of 53.1 months (1-90 months). The ETV technical parameters of difficulty were validated by seven expert neurosurgeons. The pediatric population (44) of this study represents the majority of patients (81.4%). The overall ETV success rate was 68.5%. Anomalies on the IIIVT floor resulted in an increased rate of ETV failure. The IIIVT was anomalous, and LM was thick in 33.3% of cases. Fenestration of LM was difficult in 39% of cases, and the LM and TC were opened separately in 55.6% of cases. The endoscopic third ventriculostomy success score (ETVSS) accurately predicted the level of difficulty opening the LM (p = 0.012), and the group with easy opening presented greater durability in ETV success. Neurosurgeons should be aware of the difficulty level of the overture of LM during ETV and its impact on long-term ETV effectiveness.

Historical High Complexity Neurosurgery Development of One of the Poorest Brazilian Regions

Human development rates in the Vale do Jequitinhonha, state of Minas Gerais, Brazil, called "Misery Valley," are among the lowest in the country, not to mention the often precarious psychosocial realities that daily contact with these families reveals. The history of neurosurgery at the Neurosurgical Reference Center at the Vale do Jequitinhonha e Mucuri dates from 2004, when the first neurosurgical procedures were performed in the recently organized Section of Neurosurgery. The historical surgical series shows the positive impact of the service. In 2007, the average was 3 neurosurgeries/month. In the last year, 2018, service growth boosted the record to 34.83 neurosurgeries/month. In addition to performing elective surgery, the neurosurgery team supports the emergency team by performing some neurosurgical procedures. The service number of patients operated since the development of the service is nearly 3,000. Neurosurgery at the Santa Casa de Caridade from Diamantina has been made comparable to the best national neurosurgery services.

Superficial Temporal Artery-Middle Cerebral Artery Bypass Ex Vivo Hybrid Simulator: Face, Content, Construct, and Concurrent Validity.

BACKGROUND: Cerebrovascular bypass surgical procedures require highly developed dexterity and refined bimanual technical skills. To attain such a level of prowess, neurosurgeons and residents have traditionally relied on "flat" models (without depth of field), such as chicken wings, live rats, silicone vessels, and other materials that stray far from the reality of the operating room, albeit more accessible. We have explored the use of a hybrid ex vivo simulator that takes advantage of the availability of placenta vessels and retains the complexity of surgery performed on a human skull to create a more realistic method for the development of cerebrovascular bypass surgical skills. METHODS: Twelve ex vivo simulators were constructed using 3 human placentas and 1 synthetic human skull for each. Face, content, construct, and concurrent validity were assessed by 12 neurosurgeons (6 trained vascular surgeons and 6 general neurosurgeons) and compared with those of other bypass models. RESULTS: The fidelity grade was ranked as low (Linkert scale score, 1-2), medium (score, 3), and high (score, 4-5). The face and content validity of the model showed high fidelity to superficial temporal artery-middle cerebral artery bypass surgery. Construct validity showed that cerebrovascular neurosurgeons had better performance, and concurrent validity highlighted that all surgical steps were present. CONCLUSION: The simulator was found to have strong face and content, construct, and concurrent validity for microsurgical cerebrovascular training, allowing for simulation of all surgical steps of the bypass procedure. The hybrid simulator seems to be a promising method for shortening the bypass surgery learning curve. However, more studies are required to evaluate the predictive validity of the model.

Prevalence and management of refractory meralgia paresthetica in lumbar spine surgery: 5 years of experience / Prevalência e manejo da meralgia parestésica refratária em cirurgia de coluna lombar: experiência de cinco anos / Prevalencia y manejo de la meralgia parestésica refractaria en cirugía de columna lumbar: experiencia de 5 años

ABSTRACT Objective The objective of our study was to report 5 years of experience in the recognition and management of refractory meralgia paresthetica (MP) in patients who had undergone posterior approach lumbar surgery. Methods Patients who were submitted to procedures in the lumbar spine from January 2010 to January 2015 in three different hospital centers in Belo Horizonte/MG were selected for an evaluation of the postoperative development of MP. A prospective observational comparative case series study. Level of evidence III. Evaluation of the following parameters: type of support for the patient, surgical time, body mass index. Results 367 posterior approach lumbar spine surgeries for degenerative pathologies of the lumbar spine were performed. MP was observed in 81 patients (22%). In 65 of those patients (80%), there was complete resolution of the symptoms with conservative management (local measures and medications for neuropathic pain) in less than two months. Twelve patients improved with a corticosteroid depot injection in the inguinal ligament and four patients required a surgical procedure in the third month. Pneumatic support was the least involved in the development of MP, as well as surgical time <1h and body mass index <25. Conclusion Refractory MP may occur in patients submitted to posterior approach lumbar spine surgeries. Management includes local measures, medications for neuropathic pain, and corticosteroid injection in the inguinal ligament. Decompression surgery is reserved for rare refractory cases. Level of evidence III; Prospective observational study with comparative case series.

RESUMO Objetivo O objetivo do presente estudo consiste em relatar a experiência de cinco anos no reconhecimento e manejo da meralgia parestésica (MP) refratária em pacientes submetidos a cirurgias lombares por via posterior. Métodos Pacientes submetidos a procedimentos na coluna lombar, no período de janeiro de 2010 a janeiro de 2015, em três diferentes centros hospitalares de Belo Horizonte/MG, foram selecionados para avaliação do desenvolvimento da MP pós-operatória. Estudo prospectivo observacional com série de casos comparativos. Nível III de evidência. Avaliação dos seguintes parâmetros: tipo de suporte para o paciente, tempo de cirurgia, índice de massa corporal. Resultados Foram feitas 367 cirurgias por via posterior da coluna lombar para patologias degenerativas da coluna lombar. A MP foi observada em 81 pacientes (22%). Em 65 pacientes (80%), houve resolução completa dos sintomas com manejo conservador (medidas locais e medicamentos para dor neuropática) em menos de dois meses. Doze pacientes melhoraram através de infiltração com corticoide de depósito e anestésico no local no ligamento inguinal e, em quatro pacientes houve necessidade de procedimento cirúrgico no terceiro mês. O suporte pneumático foi o menos envolvido no desenvolvimento da MP, assim como o tempo cirúrgico <1h e índice de massa corporal <25. Conclusão A MP refratária pode ocorrer em pacientes submetidos a cirurgias na coluna lombar por via posterior. O manejo inclui medidas locais, medicamentos para dor neuropática e infiltração com corticoide no ligamento inguinal. A cirurgia descompressiva está reservada para os raros casos refratários. Nível de evidência III; Estudo prospectivo observacional com série de casos comparativos.

RESUMEN Objetivo El objetivo del presente estudio consiste en relatar la experiencia de 5 años en el reconocimiento y manejo de la meralgia parestésica (MP) refractaria en pacientes sometidos a cirugías lumbares por vía posterior. Métodos Pacientes sometidos a procedimientos en la columna lumbar, en el período de enero de 2010 a enero de 2015, en tres diferentes centros hospitalarios de Belo Horizonte/MG, fueron seleccionados para evaluación del desarrollo de la MP postoperatoria. Estudio prospectivo observacional con serie de casos comparativos. Nivel III de evidencia. Evaluación de los siguientes parámetros: tipo de soporte para el paciente, tiempo de cirugía, índice de masa corporal. Resultados Se realizaron 367 cirugías por vía posterior de la columna lumbar para patologías degenerativas de la columna lumbar. La MP fue observada en 81 pacientes (22%). En 65 pacientes (80%) hubo resolución completa de los síntomas con manejo conservador (medidas locales y medicamentos para el dolor neuropático) en menos de 2 meses. Doce pacientes mejoraron a través de infiltración de corticoide de depósito y anestésico en el local en el ligamento inguinal y, en cuatro pacientes, hubo necesidad de procedimiento quirúrgico en el tercer mes. El soporte neumático fue el menos involucrado en el desarrollo de la MP, así como el tiempo quirúrgico <1h e índice de masa corporal <25. Conclusión La MP refractaria puede ocurrir en pacientes sometidos a cirugías en la columna lumbar por vía posterior. El manejo incluye medidas locales, medicamentos para el dolor neuropático e infiltración con corticoide en el ligamento inguinal. La cirugía descompresiva está reservada para los raros casos refractarios. Nivel de evidencia III; Estudio prospectivo observacional con serie de casos comparativos.

Development and validation of the Skills Assessment in Microsurgery for Brain Aneurysms (SAMBA) instrument for predicting proficiency in aneurysm surgery.

OBJECTIVE: Surgical performance evaluation was first described with the OSATS (Objective Structured Assessment of Technical Skills) and modified for aneurysm microsurgery simulation with the OSAACS (Objective Structured Assessment of Aneurysm Clipping Skills). These methods rely on the subjective opinions of evaluators, however, and there is a lack of objective evaluation for proficiency in the microsurgical treatment of brain aneurysms. The authors present a new instrument, the Skill Assessment in Microsurgery for Brain Aneurysms (SAMBA) scale, which can be used similarly in a simulation model and in the treatment of unruptured middle cerebral artery (MCA) aneurysms to predict surgical performance; the authors also report on its validation. METHODS: The SAMBA scale was created by consensus among 5 vascular neurosurgeons from 2 different neurosurgical departments. SAMBA results were analyzed using descriptive statistics, Cronbach's alpha indexes, and multivariate ANOVA analyses (p < 0.05). RESULTS: Expert, intermediate-level, and novice surgeons scored, respectively, an average of 33.9, 27.1, and 16.4 points in the real surgery and 33.3, 27.3, and 19.4 points in the simulation. The SAMBA interrater reliability index was 0.995 for the real surgery and 0.996 for the simulated surgery; the intrarater reliability was 0.983 (Cronbach's alpha). In both the simulation and the real surgery settings, the average scores achieved by members of each group (expert, intermediate level, and novice) were significantly different (p < 0.001). Scores among novice surgeons were more diverse (coefficient of variation = 12.4). CONCLUSIONS: Predictive validation of the placenta brain aneurysm model has been previously reported, but the SAMBA scale adds an objective scoring system to verify microsurgical ability in this complex operation, stratifying proficiency by points. The SAMBA scale can be used as an interface between learning and practicing, as it can be applied in a safe and controlled environment, such as is provided by a placenta model, with similar results obtained in real surgery, predicting real surgical performance.

Learning brain aneurysm microsurgical skills in a human placenta model: predictive validity.

OBJECTIVE Surgery for brain aneurysms is technically demanding. In recent years, the process to learn the technical skills necessary for these challenging procedures has been affected by a decrease in the number of surgical cases available and progressive restrictions on resident training hours. To overcome these limitations, surgical simulators such as cadaver heads and human placenta models have been developed. However, the effectiveness of these models in improving technical skills is unknown. This study assessed concurrent and predictive validity of brain aneurysm surgery simulation in a human placenta model compared with a "live" human brain cadaveric model. METHODS Two human cadaver heads and 30 human placentas were used. Twelve neurosurgeons participated in the concurrent validity part of this study, each operating on 1 human cadaver head aneurysm model and 1 human placenta model. Simulators were evaluated regarding their ability to simulate different surgical steps encountered during real surgery. The time to complete the entire aneurysm task in each simulator was analyzed. The predictive validity component of the study involved 9 neurosurgical residents divided into 3 groups to perform simulation exercises, each lasting 6 weeks. The training for the 3 groups consisted of educational video only (3 residents), human cadaver only (3 residents), and human placenta only (3 residents). All residents had equivalent microsurgical experience with superficial brain tumor surgery. After completing their practice training, residents in each of the 3 simulation groups performed surgery for an unruptured middle cerebral artery (MCA) aneurysm, and their performance was assessed by an experienced vascular neurosurgeon who watched the operative videos. RESULTS All human cadaver heads and human placentas were suitable to simulate brain aneurysm surgery. In the concurrent validity portion of the experiment, the placenta model required a longer time (p < 0.001) than cadavers to complete the task. The placenta model was considered more effective than the cadaver model in simulating sylvian fissure splitting, bipolar coagulation of oozing microvessels, and aneurysm neck and dome dissection. Both models were equally effective in simulating neck aneurysm clipping, while the cadaver model was considered superior for simulation of intraoperative rupture and for reproduction of real anatomy during simulation. In the predictive validity portion of the experiment, residents were evaluated for 4 tasks: sylvian fissure dissection, microvessel bipolar coagulation, aneurysm dissection, and aneurysm clipping. Residents trained in the human placenta simulator consistently had the highest overall performance scores when compared with those who had trained in the cadaver model and those who had simply watched operative videos (p < 0.001). CONCLUSIONS The human placenta biological simulator provides excellent simulation for some critical tasks of aneurysm surgery such as splitting of the sylvian fissure, dissection of the aneurysm neck and dome, and bipolar coagulation of surrounding microvessels. When performing surgery for an unruptured MCA aneurysm, residents who had trained in the human placenta model performed better than residents trained with other simulation scenarios/models. In this age of reduced exposure to aneurysm surgery and restrictions on resident working hours, the placenta model is a valid simulation for microneurosurgery with striking similarities with real surgery.

Titanium versus polyetheretherketone implants for vertebral body replacement in the treatment of 77 thoracolumbar spinal fractures.

BACKGROUND: Titanium and polyetheretherketone (PEEK) implants have been used in spinal surgery with low rejection rates. Compared to titanium, PEEK has many advantages, including a density more similar to that of bone, radiolucency, and a lack of artifacts in computed tomography (CT) and magnetic resonance imaging (MRI). In this study, we evaluated the effectiveness of PEEK cages as an alternative to titanium for bone fusion after fractures of the thoracolumbar spine. We also propose a classification to the impaction index. METHODS: We evaluated 77 patients with fractures of the thoracic or lumbar spine who were treated by anterior fixation with titanium cages (TeCorp®) in 46 (59.7%) patients or PEEK (Verte-stak®) in 31 (40.3%) patients from 2006 to 2012 (Neurological Hospital of Lyon). RESULTS: The titanium group achieved 100% fusion, and the PEEK group achieved 96.3% fusion. The titanium systems correlated with higher impact stress directed toward the lower and upper plateaus of the fused vertebrae; there were no nonunions for those treated with titanium group. Nevertheless, there was only one in the PEEK group. There was no significant difference in the pain scale outcomes for patients with ±10 degrees of the sagittal angle. Statistically, it is not possible to associate the variation of sagittal alignment or the impaction with symptoms of pain. The complication rate related to the implantation of cages was low. CONCLUSIONS: Titanium and PEEK are thus equally effective options for the reconstruction of the anterior column. PEEK is advantageous because its radiolucency facilitates the visualization of bone bridges.

Sphenopterional Point: Strategic Point for Burr Role Placement in Frontotemporal Craniotomies.

BACKGROUND: Frontotemporal craniotomies are the most commonly performed neurosurgical approaches. We studied the external bony landmarks on the lateral surface of the skull to identify a "strategic" point where both the anterior and middle cranial fossae are exposed simultaneously during frontotemporal craniotomies through a single burr hole placed over the greater wing of the sphenoid bone (sphenopterional point). OBJECTIVE: This study aimed to anatomically define the sphenopterional point via craniometric measurements taken on the lateral surface of the human skull. METHODS: This study used 100 adult (age >18 years old) human dry crania (200 sides) with the calvaria removed, which were cataloged by gender and age. By using laser transillumination, the sphenopterional point was accurately identified in the temporal fossa. Measurements were taken using easily identifiable bony landmarks. On the basis of these landmarks, the horizontal and vertical distances were established between the sphenopterional point and the frontozygomatic suture. RESULTS: Regardless of gender or the side of the skull, the mean horizontal distance was 21.72 mm (SD, 3.17 mm; range, 14.25 mm-32.58 mm), and the mean vertical distance was 4.76 mm (SD, 1.74 mm; range, 0.00-9.73 mm). Neither the horizontal (right side, P = 0.621; left side, P = 0.341) nor the vertical measurements (right side, P = 0.460; left side, P = 0.609) differed significantly between genders. Therefore males and females present, on average, the same vertical and horizontal measurements on both sides. CONCLUSIONS: According to our measurements, the sphenopterional point is located, on average, 21.72 mm posterior and 4.76 mm superior from the frontozygomatic suture, over the sphenoidal bone component of the pterion region.

Head Measurements for the Diagnosis of Craniosynostosis

Objective Craniosynostosis is a group of growth disturbances of the skull, which can result in serious consequences for the children who suffer from it. Early diagnosis provides treatment at the correct time. Most of the time, the pediatrician uses the head circumference (HC) as a parameter for the diagnosis, but the HC does not appear to be changed in this disease, leading to incorrect interpretations. The anteroposterior distance (APD) and biauricular distance (BAD) appear to be more accurate. The aim of this study is to analyze the value of the HC and the ratio between the measurements of the APD and the BAD for this diagnosis. Methods We analyzed the data from 129 children who had already undergone an operation for craniosynostosis at an institution in Southeastern Brazil. These data were compared with the normal standards of the population and statistically analyzed to establish their alterations. Results The HC did not change significantly in cases of craniosynostosis, neither when it was considered as a single disease, nor when considering the different subtypes. The APD/BAD ratio changed significantly in the group. Conclusion The HC does not appear to be useful in the diagnosis of craniosynostosis as an individual parameter. The APD/BAD ratio appears to help in the diagnosis.

Objetivo Craniossinostoses são alterações do crescimento do crânio que podem resultar graves consequências para a criança. O diagnóstico precoce propicia o tratamento correto. O perímetro cefálico (PC) é habitualmente usado como parâmetro para o diagnóstico. Porém, como na maioria das vezes há alteração na forma e não no perímetro, sua utilização isolada pode levar a detecção tardia. As medidas do diâmetro ântero posterior (DAB) e bi auricular (DBA) parecem ser mais precisas. O objetivo do trabalho é analisar o valor do PC no diagnóstico, bem como o da razão entre as medidas DAP/ DBA. Métodos Foram analisadas dados de 139 crianças já operadas no Biocor Instituto, em Minas Gerais. Os dados foram comparados com os parâmetros normais já conhecidos da população. Resultados O PC não se alterou de maneira significativa nas craniossinostoses, seja como um grupo único ou nos subtipos. A razão das medidas DAP/ DBA alterou-se. Conclusão O PC isolado parece não ser útil para o diagnóstico das craniossinostoses. A razão das medidas DAP/ DBA parecendo ter utilidade.

The Anterolateral Limit of the Occipital Lobe: An Anatomical and Imaging Study.

Objectives The boundaries of the temporal lobe, the parietal lobe, and the anterior portion of the occipital lobe (OL) are poorly defined. Lesions in these areas can be difficult to localize. Therefore, we studied the anterolateral limit of the OL to identify reliable anatomical landmarks. Design In 10 formalin-fixed cadaveric heads, the boundaries of the OL and relative anatomical landmarks were studied. Main Outcome Measures Distances between the following structures were measured: (1) preoccipital tentorial plica (POTP) to the junction between lambdoid suture and superior border of the transverse sinus (POTP-SL), (2) POTP to the sinodural angle of Citelli (POTP-PP), (3) lambda to parietooccipital sulcus (L-POS), and (4) preoccipital notch to termination of the vein of Labbé (PON-VL). Landmarks in 559 computed tomography and magnetic resonance images were also studied. Results The POTP was found on the tentorium of all anatomical specimens, located at the same coronal level as the PON and its attachment to the bony protuberance (BP) at the lateral cranial wall. The mean distances were POTP-SL, 6.5 ± 6.4 mm; POTP-PP, 18.1 ± 7.8 mm; L-POS, 10.8 ± 5.0 mm; and PON-VL, 8.8 ± 10.1 mm. Conclusion Osseous (asterion, lambda, and BP), dural (POTP), and vascular (VL) landmarks can be used as reference structures to identify the anterolateral limit of the OL.

Long-Term Follow-Up of Anterior Pituitary Deficiency after Aneurysmal Subarachnoid Hemorrhage: Prospective Cohort.

OBJECTIVE: The aim of this study was to evaluate the prevalence of hypopituitarism in the acute stage after aneurysmal subarachnoid hemorrhage (SAH) as well at the chronic stage, at least 1 year after bleeding, to assess its implications and correlation with clinical features of the studied population. PATIENTS AND METHODS: This was a prospective cohort study that evaluated patients admitted between December 2009 and May 2011 with a diagnosis of SAH secondary to cerebral aneurysm rupture. Clinical and endocrine assessment was performed during the acute stage after hospital admission and before treatment at a mean of 7.5 days (SD ± 3.8) following SAH, and also at the follow-up visit at a mean of 25.5 months (range: 12-55 months) after the bleeding. RESULTS: Out of the 119 patients initially assessed, 92 were enrolled for acute stage, 82 underwent hormonal levels analysis, and 68 (82.9%) were followed up in both acute and chronic phases. The mean age and median age were lower among patients with dysfunction in the acute phase compared to those without dysfunction (P < .05). The prevalence of dysfunction in the acute phase was higher among patients with hydrocephalus on admission computed tomography (57.9%) than among those without it (P < .05). At chronic phase, there was an association between dysfunction and Hunt & Hess scale score greater than 2 (P < .05). CONCLUSIONS: We believe that there is not enough literature evidence to incorporate routine endocrinological evaluation for patient victims of SAH, but we should always keep this differential diagnosis in mind when conducting long-term assessments of this population.

Intracerebral hemorrhage due to cerebral amyloid angiopathy after head injury: Report of a case and review of the literature.

Cerebral amyloid angiopathy (CAA) is an important cause of spontaneous intracerebral hemorrhage in the elderly. A few case reports of CAA-related intracerebral hemorrhage after head injury, usually following a fall, have been published. More rarely, it may occur in the setting of a traffic accident, with only four cases having been reported. We describe a case of CAA-related intracerebral hemorrhage in an 88-year-old man injured in a road traffic accident. The patient died 14 h after the accident. Autopsy examination revealed a left frontoparietal hematoma and CAA of most of the small leptomeningeal and cortical arteries, as well as several capillaries, predominantly in the parietal and occipital lobes. Except for bruises in the frontal and zygomatic regions, elbow and forearm, to the left, there were no skull fractures or traumatic lesions in other parts of the body. We review the literature on CAA-related intracerebral hemorrhage associated with head injury. CAA-related intracerebral hemorrhage after head injury may occur due to a minor trauma, minor and severe falls, or in the setting of a traffic accident. However, even in this last condition, it seems to happen mostly in patients who had a mild to moderate head injury. These facts show that replacement of the contractile components of the arterial tunica media by amyloid renders the affected cerebral blood vessels more vulnerable to head injury associated with acceleration and deceleration, independently of the severity of the dynamic loading acting on the head.

Face, Content, and Construct Validity of Brain Tumor Microsurgery Simulation Using a Human Placenta Model.

BACKGROUND: Brain tumors are complex 3-dimensional lesions. Their resection involves training and the use of the multiple microsurgical techniques available for removal. Simulation models, with haptic and visual realism, may be useful for improving the bimanual technical skills of neurosurgical residents and neurosurgeons, potentially decreasing surgical errors and thus improving patient outcomes. OBJECTIVE: To describe and assess an ex vivo placental model for brain tumor microsurgery using a simulation tool in neurosurgical psychomotor teaching and assessment. METHODS: Sixteen human placentas were used in this research project. Intravascular blood remnants were removed by continuous saline solution irrigation of the 2 placental arteries and placental vein. Brain tumors were simulated using silicone injections in the placental stroma. Eight neurosurgeons and 8 neurosurgical residents carried out the resection of simulated tumors using the same surgical instruments and bimanual microsurgical techniques used to perform human brain tumor operations. Face and content validity was assessed using a subjective evaluation based on a 5-point Likert scale. Construct validity was assessed by analyzing the surgical performance of the neurosurgeon and resident groups. RESULTS: The placenta model simulated brain tumor surgical procedures with high fidelity. Results showed face and content validity. Construct validity was demonstrated by statistically different surgical performances among the evaluated groups. CONCLUSION: Human placentas are useful haptic models to simulate brain tumor microsurgical removal. Results using this model demonstrate face, content, and construct validity.

Midline as a landmark for the position of the superior sagittal sinus on the cranial vault: An anatomical and imaging study.

BACKGROUND: Craniotomies involving the midline are regular practice in neurosurgery, during which injury to the superior sagittal sinus (SSS), an uncommon yet devastating event, may occur. The midline tends to be the most common landmark used to identify the position of the SSS. In this study we examined the reliability of the midline as a landmark for the SSS. METHODS: We performed bilateral craniectomies on eight cadaveric heads, preserving the coronal, sagittal, and lambdoid sutures. The width of the SSS and its displacement from midline were measured on the cadaveric specimens and on 105 normal magnetic resonance images (MRIs) of the head at the following locations: halfway between nasion and bregma (NB), bregma (B), halfway between bregma and lambda (BL), lambda (L), and inion (I). RESULTS: In all cadaveric specimens, the SSS was partially or totally displaced toward one side of midline, usually to the right. It tended to be closer to midline in the frontal region and more displaced posteriorly. The SSS usually drained into the right-side transverse sinus. The mean width of the SSS was 4.3, 5.9, 6.9, 7.9, and 7.8 mm, and the average displacement from midline was 4.3, 6.3, 5.5, 6.9, and 6.0 mm for NB, B, BL, L, and I, respectively. These measurements were then compared with those obtained from the MRIs. CONCLUSION: The SSS was consistently displaced on either side of midline. Thus, the midline is not reliable for identifying the SSS, and caution should be used within 6-10 mm on either side of midline.

Posterior atlanto-occipital and atlanto-axial area and its surgical interest.

UNLABELLED: Classic anatomical studies describe two membranes - atlanto-occipital and atlanto-axial in the posterior aspect of the craniocervical region. During many surgical procedures in this area, however, we have not found such membranes. OBJECTIVE: To clarify the anatomical aspects and structures taking part of the posterior atlanto-occipital and atlanto-axial area. METHOD: Analysis of histological cuts of three human fetuses and anatomical studies of 8 adult human cadavers. RESULTS: In both atlanto-occipital and atlanto-axial areas, we have observed attachment between suboccipital deep muscles and the spinal cervical dura. However, anatomical description of such attachments could not be found in textbooks of anatomy. CONCLUSION: Our study shows the absence of the classical atlanto-occipital and atlanto-axial membranes; the occipito-C1 and C1-C2 posterior intervals are an open area, allowing aponeurotic attachment among cervical dura mater and posterior cervical muscles.

Posterior atlanto-occipital and atlanto-axial area and its surgical interest / Interesse cirúrgico da junção atlanto-occipital e atlanto-axial

Classic anatomical studies describe two membranes – atlanto-occipital and atlanto-axial in the posterior aspect of the craniocervical region. During many surgical procedures in this area, however, we have not found such membranes. Objective To clarify the anatomical aspects and structures taking part of the posterior atlanto-occipital and atlanto-axial area. Method Analysis of histological cuts of three human fetuses and anatomical studies of 8 adult human cadavers. Results In both atlanto-occipital and atlanto-axial areas, we have observed attachment between suboccipital deep muscles and the spinal cervical dura. However, anatomical description of such attachments could not be found in textbooks of anatomy. Conclusion Our study shows the absence of the classical atlanto-occipital and atlanto-axial membranes; the occipito-C1 and C1-C2 posterior intervals are an open area, allowing aponeurotic attachment among cervical dura mater and posterior cervical muscles. .

Em livros clássicos de anatomia é referida a existência de duas membranas, atlanto-occipital e atlanto-axial, participando do fechamento da região cranio-cervical. Entretanto, em frequentes procedimentos cirúrgicos que envolvem esta região, jamais detectamos a presença de tais membranas. Objetivo Estudar os aspectos anatômicos e as estruturas que participam do fechamento posterior dos espaços atlanto-occipital e atlanto-axial. Método Estudo de cortes histológicos de três fetos humanos e estudos anatômicos em 8 cadáveres humanos adultos. Resultados Em ambos os espaços, atlanto-occipital e atlanto-axial, encontramos uma aderência entre as estruturas musculares profundas e a dura-mater, sem as membranas atlanto-occipital e atlanto-axial descritas nos livros clássicos de anatomia. Conclusão Não foram encontradas as membranas atlanto-occipital e atlanto-axial no material estudado; os espaços atlanto-occipital e atlanto-axial são abertos permitindo expansões aponeuróticas entre os músculos profundos e a dura-mater. .

Comparative morphometric study of the sigmoid sinus sulcus and the jugular foramen.

OBJECTIVE: To compare the right and left sides of the same skulls as far as the described landmarks are concerned, and establish the craniometric differences between them. METHOD: We carried out measurements in 50 adult dry human skulls comparing both sides. RESULTS: The sigmoid sinus width at the sinodural angle level was larger on the right side in 78% of the cases and at the level of the digastric notch in 72%. The jugular foramen width was also larger on the right side in 84% of the cases. The sigmoid sinus distance at the level of the digastric notch was larger on the right side in 64% of the cases, and the sigmoid sinus distance at the level of the digastric notch to the jugular foramen was larger on the right side in 70% of the cases. CONCLUSION: Significant craniometric differences were found between both sides of the same skulls.