Onyx embolization of skull base paragangliomas: a single-center experience.

BACKGROUND: Skull base paragangliomas are highly vascular tumors that are often embolized before surgical resection; however, the safety and efficacy of preoperative embolization using an ethylene vinyl alcohol copolymer (Onyx; Medtronic, Dublin, Republic of Ireland) in these tumors is unknown. This retrospective cohort study evaluated patient outcomes after preoperative embolization of skull base paragangliomas using Onyx. METHODS: We retrospectively analyzed data from all patients with skull base paragangliomas who underwent preoperative Onyx embolization at our institution (January 01, 2005-December 31, 2017). Patient, tumor, embolization, and outcomes data were extracted by reviewing inpatient and outpatient clinical and imaging records. RESULTS: Seven patients were studied (5/7 [71%] female), 6 with glomus jugulares and 1 with a glomus vagale. The median age was 52 years, and the most common presenting symptom was cranial neuropathy (6/7 [86%]). The tumor vascular supply was from the ascending pharyngeal artery in all 7 cases (100%) with additional feeders including the occipital artery in 5 (71%); internal carotid artery in 3 (43%); middle meningeal, vertebral, and internal maxillary artery each in 2 (29%); and posterior auricular artery in 1 (14%). The median postembolization tumor devascularization was 80% (range, 64-95%). The only postembolization complication was a facial palsy in 1 patient. CONCLUSION: Preoperative embolization with Onyx affords excellent devascularization for the majority of skull base paragangliomas, and it may facilitate resection of these hypervascular lesions. The advantages provided by Onyx with respect to penetration of intratumoral vessels must be weighed against the risk of cranial neuropathy.

Supracerebellar "Flyover" Approach to Dumbbell Falcotentorial Meningioma Encasing the Galenic Venous System.

Falcotentorial meningiomas involve the tentorial apex and straight sinus, posing challenges when encasing the galenic venous system.1 Microneurosurgery is considered the best treatment option for large falcotentorial meningiomas because it provides a definitive cure.2 In contrast, Gamma Knife surgery mainly allows the control of smaller or residual tumors after microsurgical resection.3 Approach selection between interhemispheric supratentorial versa supracerebellar transtentorial is dictated by the displacement of the Galen vein.1,4-8Video 1 describes the critical surgical steps of the supracerebellar "flyover" approach for a Bassiouni type II dumbbell falcotentorial meningiomas encasing the galenic venous system. Preoperative embolization was ruled out due to potential additional morbidity and mortality risks.9,10 A perimedian supracerebellar infratentorial transtentorial approach was performed with the patient in ¾ prone Concorde position. After early devascularization and division of the tentorium, the meningioma was internally debulked while preserving the arachnoid plane. The posterior choroidal arteries, internal cerebral veins, basal veins of Rosenthal, and vein of Galen were carefully dissected, and the tumor was completely resected. The patient was discharged on postoperative day 3 with no deficits. Postoperative magnetic resonance imaging confirmed a Simpson grade 1 resection. Pathology revealed a grade 2 meningioma. The patient remained asymptomatic with no recurrence at a 10-year follow-up. The reported case demonstrates that the most critical factor in the choice of approach to midline dumbbell falcotentorial meningiomas is the relationship of the tumor to the galenic venous system and its tributaries.

Cervical to Petrous Carotid Artery High-Flow Bypass for Carotid Artery Pseudoaneurysm Through Zygomatic Approach: 2-Dimensional Operative Video.

Pseudoaneurysms of the cervical internal carotid artery may generate grave risk from catastrophic rupture, thromboembolic stroke, or mass effect. They have many causes, including malignancy, infection, and iatrogenic and most commonly blunt or penetrating trauma.1 These aneurysms require treatment to eliminate their risk. Treatment options include trapping, with or without revascularization, or endovascular stenting. Trapping without revascularization requires evaluation of the cerebral collateral under a physiological challenge, which is usually done with a balloon occlusion test, which is not applicable in this lesion.2 Occluding the carotid without revascularization carries the risk of delayed ischemia and aneurysm formation.3,4 Carotid stenting has been applied in the treatment of these lesions5,6; however, the extent of the lesion in our patient from the carotid bifurcation to the petrous carotid makes endovascular treatment challenging. We present a patient with a delayed post-traumatic pseudoaneurysm of the carotid artery that extended from the bifurcation to the petrous carotid who was treated with trapping and high-flow saphenous vein bypass from the proximal cervical internal carotid to the petrous carotid. Adequate exposure of the petrous carotid to perform anastomosis requires a thorough knowledge of the anatomy and surgical nuances, which we demonstrate here through a zygomatic approach.7 The patient consented to the procedure and publication of imaging. Image at 2:28 from Al-Mefty O, Operative Atlas of Meningiomas, © LWW, 1997, with permission.

"Save the Nerve": Technical Nuances for Hearing Preservation and Restoration in Vestibular Schwannoma Surgery: 2-Dimensional Operative Video.

Hearing loss is a significant disability that inflects dysfunction and affects the patient quality of life. Consequently, hearing preservation and the potential of hearing restoration are prized quests in the management of vestibular schwannoma.1 Although small intracanalicular vestibular schwannomas are commonly observed, progressive hearing loss occurs despite the absence of tumor growth; hence, surgical resection can be performed with the sole aim of hearing preservation in well-informed and eager patients. Hearing preservation by surgical resection has proven to be durable.1-4 In this group of patients, we concur with Yamakami et al2 that vascularized meatal flap to reconstruct the canal helps prevent scarring of the cochlear nerve and provides cerebrospinal fluid (CSF) bathing to the cochlear nerve, yielding better long-term hearing preservation. With larger tumors and more severe hearing loss at presentation, microsurgical resection should aim at preserving the cochlear nerve, a goal frequently achievable, which offers the potential for hearing restoration with cochlear implants.3 The results of cochlear implants in restoration of severe hearing loss have been to say the least most impressive.5 We demonstrate these 2 frequently encountered clinical situations with 2 surgical videos showing specific surgical tenets, including intra-arachnoidal dissection, medial to lateral manipulation of the tumor, preservation of the labyrinthine artery, as well as reconstruction of the internal auditory canal.2,3,6,7 The patients consented to the surgery and to the publication of their picture in a surgical video. Illustration in video © 1997 O. Al-Mefty. Used with permission. All rights reserved.

Clipping of Multiple Cerebral Aneurysms Through Cranioorbital Zygomatic Approach: 2-Dimensional Operative Video.

Ruptured cerebral aneurysm is a grave disease, with a high morbidity and mortality, mandating securing the aneurysm to eliminate fatal rebleeding.1 Multiple aneurysms are frequent and may occur in approximately 20% of the cases with female prominence.2 The risk of subarachnoid hemorrhage in unruptured aneurysms is higher in patients who had prior ruptured aneurysms.3 Hence, there is an indication of treating all concomitant aneurysms when one is ruptured. We present the case of clipping of 3 aneurysms via a cranioobritozygomatic (COZ) approach including a middle cerebral artery, anterior choroidal artery, and superior cerebellar artery in a patient presenting with subarachnoid hemorrhage and multiple aneurysms with suboptimal morphology for endovascular coiling. We highlight the advantages of the COZ in the clipping of complex posterior circulation aneurysms and the advantage of mobilization of neural structures to gain wider exposure.4-6 The temporal fossa space provided by zygomatic osteotomy allows the outward mobilization of the temporal lobe after freeing it by splitting the Sylvian fissure. The falciform ligament is opened overlying the optic nerve, allowing for safe dissection within the opticocarotid window. The oculomotor nerve is detethered from the dura surrounding its entry into the cavernous sinus. These maneuvers allow for mobilization of the critical neurovascular structures, which widens the operative corridor without undue traction or retraction. The COZ with clinoidectomy shortens and widens the operative field, allows for enhanced maneuverability, improved visualization, and exposure of the clinoidal carotid, and facilitates the release and mobilization of the optic and third nerve. The patient consented to surgery. Image at 1:40 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, © LWW, 1998.

Medial Acoustic Tumors: Special Considerations: 2-Dimensional Operative Video.

Medial acoustic tumors are a rare distinct type of vestibular schwannoma having distinguished clinical and radiological features.1 Originating medially in the cerebellopontine angle without extending into the lateral internal auditory meatus, they are frequently giant in size at presentation in younger patients with a relatively preserved hearing, while they have other neurological deficits from cerebellar or brainstem compression and associated hydrocephalus. Imaging typically shows a cystic tumor with local mass effect and an internal auditory canal filled with cerebrospinal fluid.1,2 Surgical resection of theses schwannoma is particularly challenging not only due to their size and hypervascularity, but also given their particular arachnoidal rearrangement inducing marked adherence to the brainstem and facial nerve.2 The treatment is surgical resection, despite, however, their giant size hearing preservation should be sought and is attainable.1-5 Transmastoid approach with squeletonization and reflection of the transverse sigmoid sinus provides lateral exposure avoiding cerebellar retraction.6 In this report, we demonstrate the specific surgical considerations applied to the resection of a giant medial acoustic tumor in a 40-yr-old patient presenting with ataxia, vertigo, facial paresthesia, and intact hearing. The patient agreed to the surgery and photography. Image at 1:44 © Ossama Al-Mefty, used with permission; Image at 8:21 from Dunn et al,2 used with permission from JNSPG.

Comparison of Surgical Outcomes and Recurrence Rates of Cystic and Solid Vestibular Schwannomas.

Objective Cystic vestibular schwannomas (CVSs) are anecdotally believed to have worse clinical and tumor-control outcomes than solid vestibular schwannomas (SVSs); however, no data have been reported to support this belief. In this study, we characterize the clinical outcomes of patients with CVSs versus those with SVSs. Design This is a retrospective review of prospectively collected data. Setting This study is set at single high-volume neurosurgical institute. Participants We queried a database for details on all patients diagnosed with vestibular schwannomas between January 2009 and January 2014. Main Outcome Measures Records were retrospectively reviewed and analyzed using univariate and multivariate analyses to study the differences in clinical outcomes and tumor progression or recurrence. Results Of a total of 112 tumors, 24% ( n = 27) were CVSs and 76% ( n = 85) were SVSs. Univariate analysis identified the extent of resection, Koos grade, and tumor diameter as significant predictors of recurrence ( p ≤ 0.005). However, tumor diameter was the only significant predictor of recurrence in the multivariate analysis ( p = 0.007). Cystic change was not a predictor of recurrence in the univariate or multivariate analysis ( p ≥ 0.40). Postoperative facial nerve and hearing outcomes were similar for both CVSs and SVSs ( p ≥ 0.47). Conclusion Postoperative facial nerve outcome, hearing, tumor progression, and recurrence are similar for patients with CVSs and SVSs. As CVS growth patterns and responses to radiation are unpredictable, we favor microsurgical resection over radiosurgery as the initial treatment. Our data do not support the commonly held belief that cystic tumors behave more aggressively than solid tumors or are associated with increased postoperative facial nerve deficits.

Direct Repair of Iatrogenic Vertebral Artery Injury Associated With Anterior Cervical Corpectomy: 2-Dimensional Operative Video.

Vertebral artery (VA) injury during anterior cervical spine surgery has potentially devastating neurovascular consequences. Our video highlights the operative nuances of exposing and directly repairing the V2 segment of the VA from an anterior approach. A 67-year-old woman undergoing anterior cervical corpectomy at another hospital began briskly bleeding from a suspected VA injury. Upon emergency transfer of the patient to our facility, angiography confirmed a right VA pseudoaneurysm at the level of the C5 corpectomy. The decision was made to repair the VA directly, thus avoiding vessel sacrifice and stenting. The previous anterior exposure was reopened. The longus colli was mobilized laterally on the right side to expose the C4 and C6 anterior tubercles. A plane was developed in the transverse foramina from C4 to C6, and the foramina were unroofed anteriorly using a high-speed drill and Kerrison rongeurs. The injured segment of the VA was exposed, and the platelet plug over the injured VA was identified. The proximal and distal ends of the injured segment were temporarily clipped, and the platelet plug was removed, revealing a small, ovoid-shaped' full-thickness arterial wall defect. The VA injury was repaired with simple running 10-0 nylon sutures. Indocyanine green angiography confirmed rapid filling of the patent lumen. The corpectomy and anterior fixation were completed. The patient was placed on aspirin therapy postoperatively. The patient remained neurologically intact without neurovascular sequelae at the 1-yr follow-up. The patient consented to surgical treatment (Institutional Review Board review was not necessary). Used with permission from Barrow Neurological Institute.

Is Falcine Meningioma a Diffuse Disease of the Falx? Case Series and Analysis of a "Grade Zero" Resection.

BACKGROUND: Falcine meningiomas have unique characteristics including their high rates of recurrence, association with high grade pathology, increased male prevalence, and potential for diffuse involvement of the falx. OBJECTIVE: To address these issues in a substantial series of falcine meningiomas and report on the impact of extent of resection for this distinct meningioma entity. METHODS: Retrospective analysis of characteristics and outcomes of 59 falcine meningioma patients who underwent surgery with the senior author. A "Grade Zero" category was used when an additional resection margin of 2 to 3 cm from the tumor insertion was achieved. RESULTS: For de novo falcine meningiomas, gross total resection (GTR) was associated with significantly decreased recurrence incidence compared with subtotal resection (P ≤ .0001). For recurrent falcine meningiomas, median progression-free survival (PFS) was significantly improved for GTR cases (37 mo vs 12 mo; P = .017, hazard ratio (HR) .243 (.077-.774)). "Grade Zero" resection demonstrated excellent durability for both de novo and recurrent cases, and PFS was significantly improved with "Grade Zero" resection for recurrent cases (P = .003, HR 1.544 (1.156-2.062)). The PFS benefit of "Grade Zero" resection did not achieve statistical significance over Simpson grade 1 during the limited follow-up period (mean 2.8 yr) for these groups. CONCLUSION: The recurrence of falcine meningiomas is related to the diffuse presence of tumor between the leaflets of the falx. Increased extent of resection including, when possible, a clear margin of falx surrounding the tumor base was associated with the best long-term outcomes in our series, particularly for recurrent tumors.

Flow diverters as a scaffold for treating direct carotid cavernous fistulas.

BACKGROUND: Direct carotid-cavernous sinus fistulas (dCCFs) are high flow arteriovenous shunts between the internal carotid artery and the cavernous sinus. Recently, we have used the pipeline embolization device (PED) to treat dCCFs. METHODS: We describe our experience treating patients with dCCFs in whom the PED was placed as the primary treatment modality. RESULTS: Five patients with dCCFs were treated with PEDs deployed in the ipsilateral internal carotid artery spanning the fistula. All patients also underwent either adjunctive transvenous or transarterial embolization. The PED served both as the primary treatment modality and as a scaffold that facilitated safe and efficacious transvenous embolysate administration by altering the flow dynamics through the fistula and providing a physical barrier that protected the internal carotid artery. No intraoperative or perioperative complications occurred. One of the five patients exhibited complete angiographic resolution of the fistula immediately after the procedure. The remaining four patients experienced complete obliteration of the fistula without additional treatment, which suggests that the PED induced alteration promoted thrombosis of the fistula. Therefore, 100% of patients in this series exhibited complete and durable obliteration of the fistula and complete resolution of symptoms following treatment. CONCLUSIONS: We believe that use of the PED to treat dCCFs may be a safe and efficacious strategy that facilitates parent vessel protection during transvenous embolization. Furthermore, the flow alterations induced by the PED may promote thrombosis of incompletely occluded fistulas. This is the largest reported series of non-iatrogenic dCCFs treated with use of the PED as the primary initial treatment strategy.

Preoperative Embolization of Skull Base Meningiomas: Outcomes in the Onyx Era.

OBJECTIVE: Preoperative embolization may facilitate skull base meningioma resection, but its safety and efficacy in the Onyx era have not been investigated. In this retrospective cohort study, we evaluated the outcomes of preoperative embolization of skull base meningiomas using Onyx as the primary embolysate. METHODS: We queried an endovascular database for patients with skull base meningiomas who underwent preoperative embolization at our institution in 2007-2017. Patient, tumor, procedure, and outcome data were analyzed. RESULTS: Twenty-eight patients (28 meningiomas) underwent successful preoperative meningioma embolization. The mean patient age ± SD was 56 ± 13 years, and 18 patients (64%) were women. The mean tumor size was 49 cm3. There were 1, 2, or 3 arterial pedicles embolized in 21 cases (75%), 6 cases (21%), and 1 case (4%), respectively. The embolized pedicles included branches of the middle meningeal artery in 19 cases (68%), the internal maxillary artery in 8 cases (29%), the ascending pharyngeal artery in 2 cases (7%), and the posterior auricular, ophthalmic, occipital, and anterior cerebral arteries in 1 case each (4%). The embolysates used were Onyx alone in 20 cases (71%), n-butyl cyanoacrylate alone in 3 cases (11%), coils/particles and Onyx/n-butyl cyanoacrylate in 2 cases each (7%), and Onyx and coils in 1 case (4%). The median degree of tumor devascularization was 60%. Significant neurologic morbidity occurred in 1 patient (4%) who developed symptomatic peritumoral edema after Onyx embolization. CONCLUSIONS: For appropriately selected skull base meningiomas supplied by dura mater-based arterial pedicles without distal cranial nerve supply, preoperative embolization with current embolysate technology affords substantial tumor devascularization with a low complication rate.

Hybrid Surgery Management of Giant Hypervascular Tumors: Intraoperative Endovascular Embolization with Microsurgical Resection.

BACKGROUND: Giant hypervascular intracranial tumors represent a formidable challenge because their size limits surgical control of the blood supply and debulking poses the risk of critical blood loss. Embolization facilitates resection but carries the risk of life-threatening tumor infarction, hemorrhage, or swelling if performed preoperatively. Endovascular intraoperative embolization avoids the fatal risk and allows the surgeon to attend instantly if any complication occurs. METHODS AND RESULTS: We report 2 cases in which combining intraoperative embolization with microsurgical resection in the hybrid operating room was used to safely and successfully remove giant hypervascular tumors. CONCLUSIONS: Intraoperative embolization facilitates the safe resection of giant hypervascular tumors and mitigates the consequences of potential tumor infarction, hemorrhage, or swelling from embolization. These cases exemplify the benefits of combining expertise in endovascular and microsurgical techniques with the capabilities of modern hybrid operating rooms allowing for their simultaneous application.

Middle meningeal arteriovenous fistulas: A rare and potentially high-risk dural arteriovenous fistula.

BACKGROUND: Middle meningeal arteriovenous fistulas (MMAVFs) are rare lesions with a poorly established natural history. We report our experience with patients with MMAVFs who presented with intracranial hemorrhage. METHODS: We reviewed our prospectively maintained endovascular database for patients with MMAVFs, who were treated by embolization during a 15-year period. Hospital and outpatient medical records and imaging studies were reviewed. RESULTS: Nine patients with MMAVFs, who presented with intracranial hemorrhage, underwent embolization (mean age 60.3 years, range 21-76; four male and five female). Four patients presented after trauma and five after spontaneous hemorrhage. All nine patients were angiographically cured after embolization of the fistula with liquid embolic agents (n = 8) or coils (n = 1). There were no procedure-related complications. CONCLUSION: MMAVFs represent a rarely reported class of vascular lesions. They are typically associated with trauma, but also develop spontaneously, and may be associated with intracranial hemorrhage, which warrants classification of these lesions as high risk. Endovascular treatment is safe and effective and should be considered for these patients, particularly for those who have lesions with intracranial venous drainage.

Low-flow and high-flow neurosurgical bypass and anastomosis training models using human and bovine placental vessels: a histological analysis and validation study.

OBJECTIVE Microvascular anastomosis is a basic neurosurgical technique that should be mastered in the laboratory. Human and bovine placentas have been proposed as convenient surgical practice models; however, the histologic characteristics of these tissues have not been compared with human cerebral vessels, and the models have not been validated as simulation training models. In this study, the authors assessed the construct, face, and content validities of microvascular bypass simulation models that used human and bovine placental vessels. METHODS The characteristics of vessel segments from 30 human and 10 bovine placentas were assessed anatomically and histologically. Microvascular bypasses were performed on the placenta models according to a delineated training module by "trained" participants (10 practicing neurosurgeons and 7 residents with microsurgical experience) and "untrained" participants (10 medical students and 3 residents without experience). Anastomosis performance and impressions of the model were assessed using the Northwestern Objective Microanastomosis Assessment Tool (NOMAT) scale and a posttraining survey. RESULTS Human placental arteries were found to approximate the M2-M4 cerebral and superficial temporal arteries, and bovine placental veins were found to approximate the internal carotid and radial arteries. The mean NOMAT performance score was 37.2 ± 7.0 in the untrained group versus 62.7 ± 6.1 in the trained group (p < 0.01; construct validity). A 50% probability of allocation to either group corresponded to 50 NOMAT points. In the posttraining survey, 16 of 17 of the trained participants (94%) scored the model's replication of real bypass surgery as high, and 16 of 17 (94%) scored the difficulty as "the same" (face validity). All participants, 30 of 30 (100%), answered positively to questions regarding the ability of the model to improve microsurgical technique (content validity). CONCLUSIONS Human placental arteries and bovine placental veins are convenient, anatomically relevant, and beneficial models for microneurosurgical training. Microanastomosis simulation using these models has high face, content, and construct validities. A NOMAT score of more than 50 indicated successful performance of the microanastomosis tasks.

Treatment of Ruptured Anterior Communicating Artery Aneurysms: Equipoise in the Endovascular Era?

BACKGROUND: Ruptured anterior communicating artery (ACoA) aneurysms are heterogeneous intracranial aneurysms whose diverse morphological features influence treatment modality. OBJECTIVE: To compare clinical outcomes and complications of all ruptured ACoA aneurysms treated by clipping or coiling in a modern institutional trial. METHODS: All patients with ruptured ACoA aneurysms in the Barrow Ruptured Aneurysm Trial were included. Clinical follow-up at 1 and 3 years was analyzed; charts were reviewed for patient demographics, aneurysm characteristics, and in-hospital complications. RESULTS: This cohort included 130 patients (mean age, 52.5 years). Mean aneurysm size was 5.8 mm. Most aneurysm domes projected anteriorly (n = 52). After randomization and crossover, 91 ACoA aneurysms (70%) were clipped and 39 (30%) were coiled. Twenty-two patients (16.9%) initially randomized to coiling crossed over to clipping after evaluation. No patients crossed over from clipping to coiling. Characteristics precluding aneurysms from coiling included unfavorable dome-to-neck ratio, lesions difficult to access by catheter, and branch vessel involvement. Aneurysm size and dome projection were not significantly associated with treatment group, clinical outcome, or retreatment. No significant difference existed in clinical outcome (modified Rankin Scale scores) between groups at discharge or at 1-year or 3-year follow-up using as-treated and intention-to-treat analyses. Retreatment was performed in 3 clipped patients (2.3%) and 3 coiled patients (2.3%). CONCLUSION: Ruptured ACoA aneurysms, regardless of size and projection, were safely treated by both treatment modalities in a large-scale randomized clinical trial. Clinical outcomes and stroke rates did not differ significantly in as-treated or intention-to-treat analyses.

Safety and Efficacy of Surgical Resection of Unruptured Low-grade Arteriovenous Malformations From the Modern Decade.

BACKGROUND: Recent studies have questioned the utility of surgical resection of unruptured brain arteriovenous malformations (bAVMs). OBJECTIVE: We performed an assessment of outcomes and complications of surgical resection of low-grade bAVMs (Spetzler-Martin grade I or II) at a single high-volume neurosurgical center. METHODS: We reviewed all unruptured low-grade bAVMs treated with surgery (with or without preoperative embolization) between January 2004 and January 2014. Stroke rate, mortality, and clinical and radiographic outcomes were examined. RESULTS: Of 95 patients treated surgically, 85 (25 grade I, 60 grade II) met inclusion criteria, and all achieved radiographic cure postoperatively. Ten patients (11.8%) were lost to follow-up; the mean follow-up of the remaining 85 was 3.3 years. Three patients (3.5%) with grade II bAVMs experienced a stroke; no patients died. Although 20 patients (23.5%) had temporary postoperative neurological deficit, only 3 (3.5%) had new clinical impairment (modified Rankin Scale score ≥2) at last follow-up. Eight of the 13 patients (61.5%) with preexisting clinical impairment had improved modified Rankin Scale scores of 0 or 1; and 17 of 30 patients (56.7%) with preoperative seizures were seizure-free without antiepileptic medication postoperatively. No significant differences existed in stroke rate or clinical outcome between grades I and II patients at follow-up (Fisher exact test, P = .55 and P > .99, respectively). CONCLUSION: Surgical resection of low-grade unruptured bAVMs is safe, with a high rate of improvement in functional status and seizure reduction. Although transient postoperative neurological deficit was observed in some patients, permanent treatment-related neurological morbidity was rare. ABBREVIATIONS: ARUBA, A Randomized Trial of Unruptured Brain Arteriovenous MalformationsbAVM, brain arteriovenous malformationmRS, modified Rankin Scale.

Carotid Endarterectomy Surgical Simulation Model Using a Bovine Placenta Vessel.

BACKGROUND: Carotid endarterectomy (CEA) is a common, well-developed surgical procedure. Although surgical simulation is gaining in importance for residency training, CEA practice opportunities for surgical residents are limited. OBJECTIVE: To describe a new haptic CEA model. METHODS: Six bovine placentas were used to create the model. Each placenta provided about 6 large arterial and venous bifurcations. In total, 36 large-vessel bifurcations were dissected and prepared for the CEA simulation. Bovine placenta vessels were arranged to simulate the common carotid artery (CCA), internal carotid artery (ICA), and external carotid artery (ECA). The diameters and wall thicknesses were measured and compared with human CCA, ICA, and ECA parameters. RESULTS: All bovine placentas provided vessels suitable for modeling carotid artery bifurcations and CEA training. Mean ± SD diameters of simulated CCAs, ECAs, and ICAs were 11.2 ± 1.8, 4.3 ± 0.5, and 9.8 ± 3.0 mm, respectively, from nondilated veins and 8.7 ± 1.4, 4.4 ± 1.3, and 7.2 ± 1.7 mm, respectively, from nondilated arteries. Mean vessel wall thicknesses were 2.0 ± 0.6 mm for arteries and 1.4 ± 0.5 mm for veins. Placental vessel tissue had dimensions and handling characteristics similar to those of human carotid arteries. The CEA procedure and its subtasks, including vessel-tissue preparation and surgical skills performance, could be reproduced with high fidelity. CONCLUSION: A bovine placenta training model for CEA is inexpensive and readily available and closely resembles human carotid arteries. The model can provide a convenient and valuable simulation and practice addition for vascular surgery training.

Human placenta aneurysm model for training neurosurgeons in vascular microsurgery.

BACKGROUND: Neurosurgery, a demanding specialty, involves many microsurgical procedures that require complex skills, including open surgical treatment of intracranial aneurysms. Simulation or practice models may be useful for acquiring these skills before trainees perform surgery on human patients. OBJECTIVE: To describe a human placenta model for the creation and clipping of aneurysms. METHODS: Placental vessels from 40 human placentas that were dimensionally comparable to the sizes of appropriate cerebral vessels were isolated to create aneurysms of different shapes. The placentas were then prepared for vascular microsurgery exercises. Sylvian fissure--like dissection technique and clipping of large- and small-necked aneurysms were practiced on human placentas with and without pulsatile flow. A surgical field designed to resemble a real craniotomy was reproduced in the model. RESULTS: The human placenta has a plethora of vessels that are of the proper dimensions to allow the creation of aneurysms with dome and neck dimensions similar to those of human saccular and fusiform cerebral aneurysms. These anatomic scenarios allowed aneurysm inspection, manipulation, and clipping practice. Technical microsurgical procedures include simulation of sylvian fissure dissection, unruptured aneurysm clipping, ruptured aneurysm clipping, and wrapping; all were reproduced with high fidelity to the haptics of live human surgery. Skill-training exercises realistically reproduced aneurysm clipping. CONCLUSION: Human placenta provides an inexpensive, widely available, convenient biological tissue that can be used to create models of cerebral aneurysms of different morphologies. Neurosurgical trainees may benefit from the preoperative use of a realistic model to gain familiarity and practice with critical surgical techniques for treating aneurysms.