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.

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.

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.

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.

Stereotactic biopsy for brainstem tumors: comparison of transcerebellar with transfrontal approach.

BACKGROUND: An important aspect of evaluating patients submitted to stereotactic biopsy of the brainstem is the trajectory used. The literature describes two principal approaches: the suboccipital transcerebellar and the transfrontal; however, no studies exist comparing these two techniques. OBJECTIVE: The purpose of this study was to compare diagnosis success rates and complications between the suboccipital transcerebellar and transfrontal trajectories. METHODS: The study evaluated 142 patients submitted to stereotactic biopsy. The patients presented brainstem tumors in the following areas: pons (n = 31), midbrain (n = 36), medulla (n = 2), pons-medulla (n = 30), pons-midbrain (n = 33), and midbrain-pons-medulla (n = 10). On 123 patients, the transfrontal approach was used, and on 19 the suboccipital transcerebellar approach. RESULTS: Comparing success rates between the two approaches, it was observed that in the group of patients submitted to the transfrontal approach, 95.1% (117 cases) were successful, while in those submitted to the suboccipital transcerebellar approach, 84.2% (16 cases) were successful. Despite a higher success rate among patients in the first group, the difference was not statistically significant. Regarding complications, in patients who were biopsied via the transfrontal trajectory, the morbidity rate was 9.8% (12 cases), while in patients submitted to the suboccipital transcerebellar approach, the morbidity rate was 5.3% (1 case) and the mortality rate 5.3% (1 case). CONCLUSIONS: This study verified a higher diagnosis rate in patients submitted to the transfrontal approach than in those submitted to the suboccipital transcerebellar approach (95.1 vs. 84.2%); however, the difference was not statistically significant. Regarding complications, the rate was similar in both groups of patients.

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.

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.

Decompressive craniotomy: prognostic factors and complications in 89 patients.

Decompressive craniotomy (DC) is applied to treat post-traumatic intracranial hypertension (ICH). The purpose of this study is to identify prognostic factors and complications of unilateral DC. Eighty-nine patients submitted to unilateral DC were retrospectively analyzed over a period of 30 months. Chi square independent test and Fisher test were used to identify prognostic factors. The majority of patients were male (87%). Traffic accidents had occurred in 47% of the cases. 64% of the patients had suffered severe head injury, while pupillary abnormalities were already present in 34%. Brain swelling plus acute subdural hematoma were the most common tomographic findings (64%). Complications occurred in 34.8% of the patients: subdural effusions in 10 (11.2%), hydrocephalus in 7 (7.9%) and infection in 14 (15.7%). The admittance Glasgow coma scale was a statistically significant predictor of outcome (p=0.0309).

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.

Intraoperative acute tissue expansion for the closure of large myelomeningoceles.

OBJECT: Skin closure has always been the main challenge in treating myelomeningoceles (MMCs). Most cutaneous defects can be treated with the simple undermining and primary suture of the wound edges. This is the ideal treatment, but it is not adequate in cases in which the lesions are greater than 5 cm in diameter. Numerous reconstructive procedures have been described and the results have been satisfactory. The need to mobilize large skin areas and the fact of excessive blood loss, however, are major problems in newborns. Moreover, the tissue undermining destroys most of the skin's vascularization and can harm the adaptation of the skin flaps. The authors describe a technique for primary closure of large MMC skin defects in which they use acute skin expansion during the surgical procedure. METHODS: Skin expansion was achieved by traction of the wound edges with U-shaped sutures and without the need of skin flaps. Sixteen patients with MMCs greater than 5 cm in diameter were evaluated. RESULTS: The MMC areas ranged from 30 to 64 cm2 (mean 45 cm2). Two suture systems were developed based on the quality of the skin edge and the size of the skin defect. Wound edge traction was performed in 10-minute periods. The edges were gradually approximated and this allowed the primary closure of the wound without undermining the tissue in all patients. In one patient skin necrosis developed, which was associated with compression of the malformed underlying vertebrae. CONCLUSIONS: Simplicity, low cost, and satisfactory results were the main advantages of the method and an increase in operative time was a disadvantage. The goal of this technique is not to replace the other methods, but the technique constitutes an effective option in the treatment of large MMCs.

Interlaminar epidural corticosteroid injection in the treatment of lumbosciatic pain: a retrospective analysis.

Lumbosciatica is a common condition which is associated with significant pain and disability. The aim of the present study was to examine the efficacy of interlaminar epidural corticosteroid infiltration in the treatment of lumbosciatic pain. We evaluated retrospectively sixty patients with lumbosciatic pain that a sequential interlaminar epidural administration of 40 mg methylprednisolone in 7 mL bupivacaine 0.25% was administered. Each patient was interviewed and asked about the pain according to visual analogue scale (VAS) and the level of disability according to World Health Organization previously of the epidural corticosteroid infiltration and, 1 and, 6 months after starting therapy. Independently of the initial VAS value, all patients decreased their pain score after one and six months of follow-up (p<0.05). However, only the patients with a low grade of disability showed an improvement after the treatment (p<0.05). No side effects were reported after epidural corticosteroid injections. In conclusion, interlaminar epidural corticosteroid injection in association with local anesthetic may be useful, at least for six months, as additional therapy of the conservative management of lumbosciatic pain.

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.

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.

Transbasal approach to skull base tumors: evaluation and proposal of classification.

A clinical study of the TBA was performed in 22 patients harboring tumors of the skull base. The follow-up ranged from 3 to 89 months (average, 30.5 months). The main complications were intracerebral hematoma, ptosis, and infection. One patient died (4.5%) because of an extradural hematoma. Eight patients died during the follow-up because of tumor complications. Among the survivals, the median of the Karnofsky index was 96.4. Based on this study, we propose a classification for the TBA, according to its extension.

The history of neurosurgical procedures for moyamoya disease.

Almost 50 years of research on moyamoya disease (1957-2006) has led to the development of a variety of surgical and medical options for its management in affected patients. Some of these options have been abandoned, others have served as the basis for the development of better procedures, and many are still in use today. Investigators studying moyamoya disease during this period have concluded that the best treatment is planned after studying each patient's presenting symptoms and angiographic pattern. The surgical procedures proposed for the treatment of moyamoya disease can be classified into three categories: direct arterial bypasses, indirect arterial bypasses, and other methods. Direct bypass methods that have been proposed are vein grafts and extracranial-intracranial anastomosis (superficial temporal artery-middle cerebral artery [STA-MCA] anastomosis and occipital artery-MCA anastomosis). Indirect techniques that have been proposed are the following: 1) encephaloduroarteriosynangiosis; 2) encephalomyosynangiosis; 3) encephalomyoarteriosynangiosis; 4) multiple cranial bur holes; and 5) transplantation of omentum. Other options such as cervical carotid sympathectomy and superior cervical ganglionectomy have also been proposed. In this paper the authors describe the history of the development of surgical techniques for treating moyamoya disease.

Occipital bi-transtentorial/falcine approach for falcotentorial meningioma: case report.

Lesions located in the bilateral posterior incisural space are difficult to treat due to limited exposure. The classical approaches to this area are limited for lesions located bilaterally and especially when the lesion extends also below the tentorium as it may occur with meningiomas. Kawashima et al. reported, in anatomic studies, a new occipital transtentorial approach: the occipital bi-transtentorial/falcine approach, to treat such lesions. We present a patient with a large falcotentorial meningioma, located bilaterally in the posterior incisural space. The occipital bi-transtentorial/falcine approach allowed an excellent surgical exposure and complete tumor removal with an excellent patient outcome.

[Decompressive craniectomy in children and adolescents with head injury: analysis of seven cases]. / Craniectomia descompressiva para tratamento da hipertensão intracraniana traumática em crianças e adolescentes: análise de sete casos.

INTRODUCTION: Decompressive craniectomy (DC) is a surgical technique used to treat patients with elevated intracranial pressure often found in head injury. Its indication remains a controversial issue in the pediatric population. OBJECTIVE: To report seven cases managed with this technique. METHOD: Retrospective study of seven patients, aged from 2 to 17 years, treated with unilateral DC due to increased intracranial pressure (ICP) as a consequence of head injury. All patients had ICP monitored post operatively and the DC classified as ultra-early (<6h), early (6-12h) or late (>24h) according to the time of its application. The minimum follow-up was six months. RESULTS: Patients were evaluated with CT scans and clinical exams, and graded according the Glasgow Outcome Scale (GOS). Three patients deceased (GOS1), one was in vegetative state (GOS2), two recovered but still requiring nursing care (GOS3 and 4), and one had a full recovery (GOS5) at hospital discharge. After six months the GOS2 and a GOS3 patients achieved full recovery (GOS5). Subdural collection (2), hydrocephalus (1) and superficial infection (1) occurred as complication. Two patients had autologous cranioplasty and the other two heterologous cranioplasty. CONCLUSION: Decompressive craniectomy remains a feasible treatment method to lower the ICP, but is not safe from complications. A multicentric study should be done for appropriate protocol treatment of pediatric patients.

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.

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.

A new device with pressure regulation for microsurgical suction: technical note.

A new suction tube that allows precise control of suction pressure during microsurgical procedures is described. The new device consists of a suction tube that has a series of small holes on its proximal end. These holes can be progressively opened or closed by a laterally placed sliding bar. The surgeon can readily adjust the suction pressure by slightly moving his thumb up and down with accordance to his convenience during the operation. This creates an easy and prompt way to regulate suction pressure, thus removing the need of suction adjustment by the assistant or the scrub nurse. This new device provides an easy, precise, and quick suction regulation during the different stages of the microsurgical procedure. When the holes are totally closed, a maximum suction pressure is achieved, and when the holes are fully opened the suction pressure can be brought to zero. This device is very simple and ergonomic and allows an adjustable suction pressure mechanism that is regulated by the surgeon. By smoothly using the thumb to move the sliding bar up and down, the suction pressure may vary within the range of a maximum to zero almost instantaneously providing the appropriate suction pressure at any surgical time.