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.

Grapefruit Training Model for Distal Anterior Cerebral Artery Side-to-Side Bypass.

OBJECTIVE: Simulation models enable trainees to master microsurgical skills before performing surgeries. Vascular bypass is a critical component of cerebrovascular and many nonneurologic procedures. However, most available bypass training models lack important spatial, tactile, and physiologic aspects of real surgery. Animal and placental models provide true physiology but are expensive. While some models adequately simulate superficial temporal artery-middle cerebral artery bypass, there is no model for side-to-side distal anterior cerebral artery bypass. The objective is to create a realistic and inexpensive training model for this important procedure. METHODS: The depth of interhemispheric fissures in cadaver brains was compared with the grapefruit radii. Grapefruits were dissected to simulate the operative field within the deep and narrow interhemispheric fissure. Pericallosal arteries were mimicked with chicken wing vessels or synthetic tubing, with an aquarium pump providing closed circulation. Twelve board-certified neurosurgeons who were given bypass training using the grapefruit model were blindly surveyed on model realism and training suitability. RESULTS: Grapefruit depths from pith to central column were comparable with interhemispheric cadaveric fissure depths. Approximate preparation time of grapefruit training models was 5-10 minutes. Surveyed neurosurgeons rated the model a better replicate for cerebral artery bypass (P < 0.02) and more challenging than common training models (P < 0.01). They also rated the grapefruit model as likely to be superior for improving surgical skills before surgery (P < 0.05). CONCLUSIONS: This grapefruit model provides a realistic simulation of side-to-side distal anterior cerebral artery bypass procedure that can be inexpensively and easily implemented in nearly any resource environment.

Surgical options in experimental porcine model for endovascular training in complex vascular lesions.

We describe a new, elegant, two-phase, microsurgical method that minimizes the surgical preparation time for different complex vascular lesions in a swine model. In the first phase, the model is prepared microsurgically in the experimental laboratory using arterial or/and venous grafts. In the second phase, the model is implanted in the experimental animal. This two-fold method allows for increasing the complexity and accuracy of the model while reducing preparation time on the day of the training session.

Human Placenta Simulator for Intracranial-Intracranial Bypass: Vascular Anatomy and 5 Bypass Techniques.

BACKGROUND: Intracranial-intracranial (IC-IC) bypass surgery involves the use of significant technical bimanual skills. Indications for this procedure are limited, so training in a simulator with brain vessels similarity could maintain microsurgical dexterity. Our goal is to describe the human placenta vascular anatomy to guide IC-IC bypasses apprenticeship. METHODS: Human placenta vascular anatomy was reported and validated with comparison to brain main vessels after studying the vascular tree of 100 placentas. Five simulated IC-IC bypasses (end to end, end to lateral, lateral to lateral, aneurysm bridge, and aneurysm exiting branch transposition) were developed and construct and concurrent validated. Statistical analysis using the t variance test was performed with a confidence interval of 0.95. RESULTS: A total of 1200 placenta vessels were used for test-retest validation with a reliability index of 0.95. All 100 human placentas were suitable to perform the 5 different bypasses. Construct validity showed a P < 0.005. Concurrent validity highlighted the technical differences among simulators. CONCLUSIONS: An ex vivo bypass model offers great similarity to main brain vessels with the possibility to practice a variety of IC-IC bypass techniques in a single simulator. Placenta vascular anatomy knowledge can improve laboratory microsurgical training.

A Portable Training Model for Deep Bypass Surgery.

INTRODUCTION: Deep bypass surgery remains a challenging operative procedure. For novice trainees, there is a high barrier to improving the microsurgical skills needed for this procedure because of the relatively low number of cases and the high cost of microsurgical instruments. Here, the authors introduce a training model that includes highly accessible devices and does not require a microscope. MATERIALS AND METHODS: The surgical environment consisted of two 15.5-cm straight serrated forceps with a 1-mm tip width (Medicon, Tuttlingen, Germany), 9-cm curved iris scissors (Medicon), 4-0 black silk suture, gauze, and a 15 × 10.5 × 3.5-cm-sized box with a transparent cover. These materials are affordable even in low-income countries. PROCEDURE: To understand and learn the hand positioning used in the deep surgical field, suturing practice was performed as follows: the forceps and a needle were placed in a slanted position, with hand position maintained at a 50° angle between the 2 forceps. This was also performed above the desk, without wrist support. CONCLUSIONS: Our training system will be helpful, especially for deep bypass surgery, since training with similar muscle effort and fatigue can improve surgical skills. This system is economic, highly accessible, and available even for portable training.

[A model of the arterial aneurysm of the brain for microneurosurgical training].

Clipping of arterial aneurysms of the brain is one of technically complex neurosurgical interventions. In the available literature, there is no information about simulation models of aneurysm clipping that have tactile properties similar to the real ones. The study presents a technical rationale for the development of a new model for the aneurysm on human placental vessels to train skills of isolating and clipping under ruptured and unruptured aneurysm conditions.

[Neurologist and emergency neuroendovascular revascularization -training programs for endovascular procedures-].

Emergency neuroendovascular revascularization is a reperfusion therapy for acute stroke. The operator for this therapy has to obtain a license as a specialist in endovascular procedures. For neurologists wishing to acquire this license, there are two kinds of training programs: full-time training and concurrent training. Full-time training was chosen by the first author of this review, while concurrent training will be performed by staff in the author's department. The advantage of full-time training is the acquisition of a lot of experience of various diseases that are treated with endovascular procedures and managed in the periprocedural period. However, full-time training has the disadvantages of a requirement to discontinue medical care of neurological diseases except for stroke and employment at a remote institution. The advantages and disadvantages of concurrent training are the reverse of those of full-time training. Neither training system can succeed without cooperation from Departments of Neurology in neighboring universities and the institutional Department of Neurosurgery. It is particularly important for each neurologist to establish a goal of becoming an operator for recanalization therapy alone or for all fields of endovascular procedures because training will differ for attainment of each operator's goal.

[Education for stroke neurologists in neuroendovascular revascularization therapy of acute ischemic stroke].

Outcome of large cerebral artery occlusions in intravenous recombinant tissue plasminogen activator failed and ineligible patients has been improved by Mechanical clot retrievers. The key words of revascularization therapies are improvement of reperfusion rate and shortening of reperfusion time. Stroke neurologists have to acquire skill of neuroendovascular therapy technique, because acute stroke patients are examined first by stroke neurologists. However acquisition of neuroendovascular skills are not easy for stroke neurologists. It is important that we establish the educational systems of neuroendovascular therapy for stroke neurologists.

Laboratory training in the retrosigmoid approach using cadaveric silicone injected cow brain.

BACKGROUND: A neurosurgical laboratory training model is designed for trainees in microneurosurgery to learn to handle surgical microscopes and microneurosurgical instruments. The silicone injection of a fresh cadaveric cow cranium is an alternative to using a cadaveric human brain for becoming familiar with the cerebellopontine angle (CPA) via the retrosigmoid approach. To report an improved method for training in the CPA via the retrosigmoid approach, using a fresh cadaveric cow cranium injected with silicone. METHODS: The material consists of a cadaveric cow brain injected with silicone. Preparation consists of irrigation of the major vessels followed by injection of silicone, coloured either red or blue. RESULTS: A three-step approach was designed to simulate microneurosurgical dissection along with the cerebellopontine angle and to dissect cranial nerves emerging from the brain stem. CONCLUSION: This laboratory training model is useful in allowing trainees to gain experience with the use of an operating microscope and familiarity with the CPA via the retrosigmoid approach. The aim of this study was to develop a novel model and to adapt it to create a life-like neurosurgical training system.

The practice of knots untying technique using a 10-0 nylon suture and gauze to cope with technical difficulties of microvascular anastomosis.

INTRODUCTION: We report a training technique of microvascular anastomosis readily accessible for trainees engaged in busy day-to-day clinical practice. METHOD: A table-top microscope is prepared on a table and 10-0 nylon suture (nonsterile) is used to tie two adjacent gauze fibers to form successive knots. In a second step, the knots are untied using the suture needle, which we call the knots untying technique (KUT). As the tied knots face different directions, it is difficult to guide the needle accurately through the knots without damaging or breaking the suture. And to untie all the knots within a certain time period, high controllability is required. RESULTS: The practice of KUT will allow surgeons to improve their ability to accurately guide the needle from any direction and carry out precise suturing swiftly, which will prevent vascular wall dissection during microvascular anastomosis or inability to guide the needle to a target point because of physiologic tremor. CONCLUSIONS: In our experience of training young neurosurgeons, practice of KUT contributes to shortening the duration of blood-flow blockage and helps mastering the technique of successful microvascular anastomosis.

Novel brain model for training of deep microvascular anastomosis.

Models of the brain and skull were developed using a selective laser sintering method for training in the procedures of deep microvascular anastomosis. Model A has an artificial skull with two craniotomies, providing fronto-temporal-subtemporal and suboccipital windows. The brain in Model A is soft and elastic, and consists of the brainstem and a hemispheric part with a detailed surface. Rehearsals or training for anastomosis to the insular part of the middle cerebral artery, superior cerebellar artery, posterior cerebral artery, and posterior inferior cerebellar artery can be performed through the craniotomies. Model B has an artificial skull with a bifrontal craniotomy and an artificial brain consisting of the bilateral frontal lobes with an interhemispheric fissure and corpus callosum. Rehearsals or training for anastomosis of the callosal segment of the anterior cerebral artery can be practiced through this craniotomy. These realistic models will help to develop skills for deep vascular anastomosis, which remains a challenging neurosurgical procedure, even for experienced neurosurgeons.

Performance and training standards for endovascular ischemic stroke treatment.

Stroke is the third leading cause of death in the USA, Canada, Europe, and Japan. According to the American Heart Association and the American Stroke Association, there are now 750,000 new strokes that occur each year, resulting in 200,000 deaths, or 1 of every 16 deaths, per year in the USA alone. Endovascular therapy for patients with acute ischemic stroke is an area of intense investigation. The American Stroke Association has given a qualified endorsement of intra-arterial thrombolysis in selected patients. Intra-arterial thrombolysis has been studied in two randomized trials and numerous case series. Although two devices have been granted FDA approval with an indication for mechanical stroke thrombectomy, none of these thrombectomy devices has demonstrated efficacy for the improvement of patient outcomes. The purpose of the present document is to define what constitutes adequate training to perform neuroendovascular procedures in patients with acute ischemic stroke and what performance standards should be adopted to assess outcomes. These guidelines have been written and approved by multiple neuroscience societies which historically have been directly involved in the medical, surgical and endovascular care of patients with acute stroke. The participating member organizations of the Neurovascular Coalition involved in the writing and endorsement of this document are the Society of NeuroInterventional Surgery, the American Academy of Neurology, the American Association of Neurological Surgeons/Congress of Neurological Surgeons Cerebrovascular Section, and the Society of Vascular & Interventional Neurology.

Cerebral revascularization.

During the last 10 years, there has been a revival of interest in cerebral revascularization procedures. Not only have significant progressions in surgical techniques been published, the use of more advanced diagnostic methods has led to a widening of the indications for cerebral bypass surgery. The purpose of this review is to outline the current techniques for extracranial-to-intracranial (EC/IC) and intracranial-to-intracranial (IC/IC) bypass surgery, as well as to identify the current indications for revascularization procedures based on the available literature. The excimer laser-assisted non-occlusive anastomosis (ELANA) technique is described in more detail because we think that this technique almost completely eliminates the risk of cerebral ischemia due to the temporary vessel occlusion which is currently used in conventional anastomosis techniques.