Selectively compromised inner retina function following hypoxic-ischemic encephalopathy in mice: A noninvasive measure of severity of the injury.

The intricate system of connections between the eye and the brain implies that there are common pathways for the eye and brain that get activated following injury. Hypoxia-ischemia (HI) related encephalopathy is a consequence of brain injury caused by oxygen and blood flow deprivation that may result in visual disturbances and neurodevelopmental disorders in surviving neonates. We have previously shown that the tyrosine receptor kinase B (TrkB) agonist/modulator improves neuronal survival and long-term neuroprotection in a sexually differential way. In this study, we tested the hypotheses that; 1) TrkB agonist therapy improves the visual function in a sexually differential way; 2) Visual function detected by electroretinogram (ERG) correlates with severity of brain injury detected by magnetic resonance (MRI) imaging following neonatal HI in mice. To test our hypotheses, we used C57/BL6 mice at postnatal day (P) 9 and subjected them to either Vannucci's rodent model of neonatal HI or sham surgery. ERG was performed at P 30, 60, and 90. MRI was performed following the completion of the ERG. ERG in these mice showed that the a-wave is normal, but the b-wave amplitude is severely abnormal, reducing the b/a wave amplitude ratio. Inner retina function was found to be perturbed as we detected severely attenuated oscillatory potential after HI. No sex differences were detected in the injury and severity pattern to the retina as well as in response to 7,8-DHF therapy. Strong correlations were detected between the percent change in b/a ratio and percent hemispheric/hippocampal tissue loss obtained by MRI, suggesting that ERG is a valuable noninvasive tool that can predict the long-term severity of brain injury.

Hydrocephalus Following Giant Transosseous Vertex Meningioma Resection.

Introduction Meningiomas are among the most common primary intracranial tumors. While well-described, there is limited information on the outcomes and consequences following treatment of giant-sized vertex-based meningiomas. These meningiomas have specific risks and potential complications due to their size, location, and involvement with extracalvarial soft tissue and dural sinuses. Herein, we present four giant-sized vertex transosseous meningioma cases with involvement and occlusion of the sagittal sinus, that postoperatively developed external hydrocephalus and ultimately required shunting. Methods A retrospective chart review identified patients with large vertex meningiomas that were: (1) large (>6 cm) with hemispheric (no skull base) location, (2) involvement of the superior sagittal sinus resulting in complete sinus occlusion, (3) involvement of dura resulting in a large duraplasty area, (4) transosseous involvement requiring a 5 cm or larger craniectomy for resection of invaded calvarial bone. Results Tumors were resected in all four cases, with all patients subsequently developing external hydrocephalus which required shunting within 2 weeks to 6 months postsurgery. Conclusion We believe this may be the first report of the development of hydrocephalus following surgical resection of these large lesions. Based on our observations, we propose that a combination of superior sagittal sinus occlusion and changes in brain elasticity and compliance affect the brain's CSF absorptive capacity, which ultimately lead to hydrocephalus development. We suggest that neurosurgeons be aware that postoperative hydrocephalus can quickly develop following treatment of giant-sized vertex-based meningiomas, and that correction of hydrocephalus with shunting can readily be achieved.

Surgical Strategies for Cerebral Revascularization in Patients with Limited Bypass Conduit Options and Unexpected Intraoperative Difficulties.

BACKGROUND: Cerebral bypass procedures are complex and require substantial experience and skills and thorough preoperative planning. Cerebrovascular surgeons face increasingly complex bypass cases because most routine cases are managed by endovascular means, and because increasing numbers of patients have complex medical problems that affect available and suitable bypass conduit options. We report the cases of several patients undergoing cerebral bypass with limited bypass conduit alternatives, in whom there were unexpected intraoperative difficulties requiring complex solutions. METHODS: The neurological surgery department database was reviewed to identify patients who had undergone cerebral bypass procedures during a 13-year period in whom there were limited available bypass conduits, and in whom unexpected intraoperative difficulties were encountered during cerebral bypass. RESULTS: Patient outcomes and graft patency were evaluated for 13 patients including 6 with ischemia, 3 with giant aneurysms, 2 with mycotic aneurysms, 1 with dissecting aneurysm, and 1 with gunshot-induced pseudoaneurysm. Median duration of follow-up was 43 months. In 12 of 13 patients, bypass graft/grafts were patent on the last computed tomography angiogram. In 1 patient, a prophylactic bypass procedure, the graft was not filling, probably because of lack of demand. Two patients died during follow-up of unrelated causes. CONCLUSIONS: Cerebrovascular surgeons should be versatile in dealing with patients with complex bypass. When there are limited available conduit options, we find that collaboration with other surgical specialties (e.g., plastics and vascular) is helpful. In patients in whom extreme intraoperative difficulties are expected, thorough preoperative planning with multiple backup plans should be exercised, as described in this report.

Intraoperative Shortening of Aneurysm Clips: Revisiting an Old Technique in a New Era.

BACKGROUND: It can sometimes be challenging to find a suitable clip to treat an unusual aneurysm, or when the surrounding anatomy is unusual, especially in resource-limited environments. We describe a method to modify aneurysm clips based on the method originated by Sugita et al in 1985. Herein clip modification (Clip-Mod) is used to treat anatomically difficult anterior communicating artery aneurysms. METHODS: The Department of Neurological Surgery database was reviewed to find aneurysm patients treated using modified aneurysm clips. Clip-Mod was performed during surgery by shortening the tines of titanium aneurysm clips by abrasion applied from the side of a standard 3-mm surgical diamond drill bit under constant irrigation. Note that the thickness of the tines and the clip spring were not modified or contacted by the drill. RESULTS: Four cases used modified aneurysm clips, from 648 total clip-treated aneurysms (0.6%) by 2 surgeons over a 14-year period. Three patients presented with subarachnoid hemorrhages that were determined to be due to anterior communicating artery aneurysms. One patient presented with an incidental unruptured anterior communicating artery aneurysm. All 4 patients were treated with 3-mm titanium clips shortened intraoperatively to 1- to 2-mm lengths, to achieve aneurysm obliteration without stenosing parent or perforating vessels. CONCLUSIONS: All 4 patients have done well clinically with no reoccurrences after 2-6 years' follow-up, which included angiographic evaluation. The use of this "Clip-Mod" technique thus appears useful for anterior communicating artery aneurysms. Clip-Mod could also be considered for treating other aneurysms when the "perfect" length clip is not available.

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.

Identification of the Distal Dural Ring and Definition of Paraclinoid Aneurysms According to Bony Landmarks on 3-Dimensional Computed Tomography Angiography: A Cadaveric and Radiological Study.

BACKGROUND: Determining if paraclinoid aneurysms are intradural or extradural is critical for surgical planning. OBJECTIVE: To create an easily reproducible diagnostic method based on bony anatomy that precisely locates the distal dural ring (DDR) to determine the position of paraclinoid aneurysms as intradural, transitional, or extradural. METHODS: Bilateral anatomic dissections of 10 cadaveric heads (20 sides) were performed to evaluate DDR anatomy. We observed a plane that reflects the position of the DDR passes through 4 bony landmarks: 1) The anterior clinoid-internal carotid artery intersection, 2) the optic strut, 3) the optico-carotid elevation, and 4) the base of the posterior clinoid process. This landmark-based plane can thus define the location of the DDR using 3-dimensional computed tomography angiography (CTA). This was confirmed in 27 surgical patients with intradural/transitional aneurysms and 7 patients with extradural aneurysms confirmed with magnetic resonance imaging (MRI). The DDR plane method easily classified aneurysm locations as intradural (above the DDR plane), extradural (below the DDR plane), or transitional (the DDR plane crosses the aneurysm). The aneurysm's location was subsequently confirmed intraoperatively or with MRI. RESULTS: The DDR plane method determined if paraclinoid aneurysms were intradural, transitional, or extradural in all 34 cases examined. The visibility of the anatomic features that define the DDR plane was also verified in 82% to 89% of CTA images from 100 patients. CONCLUSION: The DDR plane method provides a useful diagnostic tool to evaluate the position of the DDR and determine the anatomic location of paraclinoid aneurysms.

High-resolution diffusion tensor magnetic resonance imaging of the brainstem safe entry zones.

Operative management of intrinsic brainstem lesions remains challenging despite advances in electrophysiological monitoring, neuroimaging, and neuroanatomical knowledge. Surgical intervention in this region requires detailed knowledge of adjacent critical white matter tracts, brainstem nuclei, brainstem vessels, and risks associated with each surgical approach. Our aim was to systematically verify internal anatomy associated with each brainstem safety entry zone (BSEZ) via neuroimaging modalities commonly used in pre-operative planning, namely high-resolution magnetic resonance imaging (MRI) and diffusion tensor tractography (DTT). Twelve BSEZs were simulated in eight, formalin-fixed, cadaveric brains. Specimens then underwent radiological investigation including T2-weighted imaging and DTT using 4.7 T MRI to verify internal anatomic relationships between simulated BSEZs and adjacent critical white matter tracts and nuclei. The distance between simulated BSEZs and pre-defined, adjacent critical structures was systemically recorded. Entry points and anatomic limits on the surface of the brainstem are described for each BSEZ, along with description of potential neurological sequelae if such limits are violated. With high-resolution imaging, we verified a maximal depth for each BSEZ. The relationship between proposed safe entry corridors and adjacent critical structures within the brainstem is quantified. In combination with tissue dissection, high-resolution MR diffusion tensor imaging allows the surgeon to develop a better understanding of the internal architecture of the brainstem, particularly as related to BSEZs, prior to surgical intervention. Through a careful study of such imaging and use of optimal surgical corridors, a more accurate and safe surgery of brainstem lesions may be achieved.

The Value of White Matter Tractography by Diffusion Tensor Imaging in Altering a Neurosurgeon's Operative Plan.

OBJECTIVE: To investigate if the implementation of white matter (WM) fiber tractography by diffusion tensor imaging in presurgical planning for supratentorial tumors proximal to eloquent WM tracts can alter a neurosurgeon's operative strategy. METHODS: A retrospective review was conducted of patients with supratentorial brain tumors within eloquent WM tracts who underwent diffusion tensor imaging (DTI) tractography as part of their preoperative assessment. These patients were classified into 3 different DTI groups per the radiology reports: group 1, intact WM tracts; group 2, deviated and/or displaced WM bundles; and group 3, patients with an established WM injury (interrupted and/or destroyed tracts). A blinded prospective behavioral study followed, in which 4 neurosurgeons reviewed the preoperative images at 2 different times (magnetic resonance imaging without DTI, followed by a review of the DTI). They provided estimations about the DTI group of each individual eloquent WM category in every patient, and their planned surgical approach. RESULTS: Fifteen patients (mean age, 58.3 years) were included in the study. The neurosurgeons provided a correct DTI group estimation in 53%, 60%, and 57% of the cases that involved motor/sensory pathway tracts, optic tracts, and language tracts, respectively. The neurosurgeons underestimated DTI group 3 in the motor category and in the optic category 75% of the time. DTI did not alter the planned surgical approach. CONCLUSIONS: DTI WM tractography helped neurosurgeons to correctly identify patients with interrupted motor and optic pathway tracts so they could be more aggressive with the extent of tumor resection, despite its inability to alter the operative approach.

Effect of perioperative aspirin use on hemorrhagic complications in elective craniotomy for brain tumors: results of a single-center, retrospective cohort study.

OBJECTIVE: In daily practice, neurosurgeons face increasing numbers of patients using aspirin (acetylsalicylic acid, ASA). While many of these patients discontinue ASA 7-10 days prior to elective intracranial surgery, there are limited data to support whether or not perioperative ASA use heightens the risk of hemorrhagic complications. In this study the authors retrospectively evaluated the safety of perioperative ASA use in patients undergoing craniotomy for brain tumors in the largest elective cranial surgery cohort reported to date. METHODS: The authors retrospectively analyzed the medical records of 1291 patients who underwent elective intracranial tumor surgery by a single surgeon from 2007 to 2017. The patients were divided into three groups based on their perioperative ASA status: 1) group 1, no ASA; 2) group 2, stopped ASA (low cardiovascular risk); and 3) group 3, continued ASA (high cardiovascular risk). Data collected included demographic information, perioperative ASA status, tumor characteristics, extent of resection (EOR), operative blood loss, any hemorrhagic and thromboembolic complications, and any other complications. RESULTS: A total of 1291 patients underwent 1346 operations. The no-ASA group included 1068 patients (1112 operations), the stopped-ASA group had 104 patients (108 operations), and the continued-ASA group had 119 patients (126 operations). The no-ASA patients were significantly younger (mean age 53.3 years) than those in the stopped- and continued-ASA groups (mean 64.8 and 64.0 years, respectively; p < 0.001). Sex distribution was similar across all groups (p = 0.272). Tumor locations and pathologies were also similar across the groups, except for deep tumors and schwannomas that were relatively less frequent in the continued-ASA group. There were no differences in the EOR between groups. Operative blood loss was not significantly different between the stopped- (186 ml) and continued- (220 ml) ASA groups (p = 0.183). Most importantly, neither hemorrhagic (0.6%, 0.9%, and 0.8%, respectively; p = 0.921) nor thromboembolic (1.3%, 1.9%, and 0.8%; p = 0.779) complication rates were significantly different between the groups, respectively. In addition, the multivariate model revealed no statistically significant predictor of hemorrhagic complications, whereas male sex (odds ratio [OR] 5.9, 95% confidence interval [CI] 1.7-20.5, p = 0.005) and deep-extraaxial-benign ("skull base") tumors (OR 3.6, 95% CI 1.3-9.7, p = 0.011) were found to be independent predictors of thromboembolic complications. CONCLUSIONS: In this cohort, perioperative ASA use was not associated with the increased rate of hemorrhagic complications following intracranial tumor surgery. In patients at high cardiovascular risk, ASA can safely be continued during elective brain tumor surgery to prevent potential life-threatening thromboembolic complications. Randomized clinical trials with larger sample sizes are warranted to achieve a greater statistical power.

Revascularization for Cerebral Ischemia, Step-by-Step Demonstration of Bonnet Bypass: 3-Dimensional Operative Video.

The superficial temporal artery (STA) to the middle cerebral artery (MCA) bypass is the most common bypass type for revascularization to treat cerebral ischemia. If the ipsilateral STA is not available for anastomosis, various options for bypass conduits can be exercised. When the entire ipsilateral external carotid and its branches are not available, the contralateral STA may be used as a donor artery through an interposition graft. This technique is known as a "bonnet bypass." In this video, we demonstrate the utilization of a bonnet bypass in a 48-yr-old man with protein S deficiency, and right carotid artery occlusion with recurrent strokes and transient ischemic attacks (TIA). After exhausting nonsurgical options by treating with 2 antiplatelet drugs and supportive lifestyle changes, the patient continued to experience TIAs and watershed strokes in the right hemisphere. Angiography showed that the right anterior artery and the MCA were filled through the Circle of Willis, but the ipsilateral STA and entire external and common carotid arteries were not patent for potential use as a bypass donor. Since the ipsilateral bypass options were not available, we elected to perform a bypass from the contralateral STA trunk to the ipsilateral M2 with a saphenous vein interposition graft, for a so-called bonnet bypass. The patient did well after surgery and has remained symptom-free for 19 mo post bypass. The surgical technique and each step in performing this bonnet bypass are demonstrated in this 3-dimensional video. The patient consented to the publication of his operative video.

Attenuation of Retinal Vascular Development in Neonatal Mice Subjected to Hypoxic-Ischemic Encephalopathy.

A significant proportion of children that survive hypoxic-ischemic encephalopathy (HIE) develop visual impairment. These visual deficits are generally attributed to injuries that occur in the primary visual cortex and other visual processing systems. Recent studies suggested that neuronal damage might also occur in the retina. An important structure affecting the viability of retinal neurons is the vasculature. However, the effects of HIE on the retinal neurovasculature have not been systemically evaluated. Here we investigated whether exposure of postnatal day 9 (P9) neonatal mice to HIE is sufficient to induce neurovascular damage in the retina. We demonstrate that the blood vessels on the surface of the retina, from mice subjected to HIE, were abnormally enlarged with signs of degeneration. The intermediate and deep vascular layers in these retinas failed to form normally, particularly in the periphery. All the vascular damages observed here were irreversible in nature up to 100 days post HIE. We also observed loss of retinal neurons, together with changes in both astrocytes and Müller cells mainly in the inner retina at the periphery. Collectively, our findings suggest that HIE results in profound alterations in the retinal vasculature, indicating the importance of developing therapeutic strategies to protect neurovascular dysfunction not only in the brain but also in the retina for infants exposed to HIE.

A novel, low-cost, reusable, high-fidelity neurosurgical training simulator for cerebrovascular bypass surgery.

OBJECTIVECerebrovascular bypass surgery is a challenging yet important neurosurgical procedure that is performed to restore circulation in the treatment of carotid occlusive diseases, giant/complex aneurysms, and skull base tumors. It requires advanced microsurgical skills and dedicated training in microsurgical techniques. Most available training tools, however, either lack the realism of the actual bypass surgery (e.g., artificial vessel, chicken wing models) or require special facilities and regulations (e.g., cadaver, live animal, placenta models). The aim of the present study was to design a readily accessible, realistic, easy-to-build, reusable, and high-fidelity simulator to train neurosurgeons or trainees on vascular anastomosis techniques even in the operating room.METHODSThe authors used an anatomical skull and brain model, artificial vessels, and a water pump to simulate both extracranial and intracranial circulations. They demonstrated the step-by-step preparation of the bypass simulator using readily available and affordable equipment and consumables.RESULTSAll necessary steps of a superficial temporal artery-middle cerebral artery bypass surgery (from skin opening to skin closure) were performed on the simulator under a surgical microscope. The simulator was used by both experienced neurosurgeons and trainees. Feedback survey results from the participants of the microsurgery course suggested that the model is superior to existing microanastomosis training kits in simulating real surgery conditions (e.g., depth, blood flow, anatomical constraints) and holds promise for widespread use in neurosurgical training.CONCLUSIONSWith no requirement for specialized laboratory facilities and regulations, this novel, low-cost, reusable, high-fidelity simulator can be readily constructed and used for neurosurgical training with various scenarios and modifications.

The Tonsillouvular Fissure Approach: Access to Dorsal and Lateral Aspects of the Fourth Ventricle.

OBJECTIVE: Although approaches to the fourth ventricle (FV) have been studied well, approaches to the lesions located in the dorsal and lateral aspects of the FV have not been shown in anatomic or clinical studies. The aim of this study is to show for the first time in the literature the tonsillouvular fissure approach (TUFA) in anatomic dissections and its use in surgical series. METHODS: For anatomic studies, 4 formalin-fixed human cadaveric heads infused with colored silicone and 10 cerebellar specimens were dissected in a stepwise manner. Records of 12 patients operated on via TUFA were also retrospectively reviewed. RESULTS: Neurosurgical anatomy and critical steps of TUFA were described in detail. Among 12 patients with lesions around the FV (4 cavernous malformation, 2 pilocytic astrocytoma, 2 hemangioblastoma, 1 B-cell lymphoma, 1 metastatic papillary carcinoma, 1 dermoid cyst, and 1 arteriovenous malformation), 11 gross total and 1 subtotal resection were achieved via TUFA without any mortality or morbidity. Comparative analyses of 4 surgical approaches to FV (TUFA, telovelar/cerebellomedullary fissure, supratonsillar/tonsillobiventral lobule fissure, and transvermian approaches) were also presented. CONCLUSIONS: TUFA provides a direct route and excellent surgical view to lesions around the FV, particularly on dorsal and lateral aspects, inferior vermis, and medial part of the dentate nucleus and cerebellar peduncles. It minimizes traversing the normal cerebellar tissue compared with a transvermian approach.

Hypertrophic Olivary Degeneration: Neurosurgical Perspective and Literature Review.

BACKGROUND: Hypertrophic olivary degeneration (HOD) occurs because of posterior fossa or brainstem lesions that disrupt the dentato-rubro-olivary tract, well known as the Guillain-Mollaret triangle. Clinical and radiologic hallmarks of this condition are palatal myoclonus and T2 hyperintensity of the inferior olivary complex on magnetic resonance imaging (MRI), respectively. Because symptomatic HOD can complicate the recovery of patients with posterior fossa or brainstem lesions, the purpose of this study is to evaluate clinical and imaging findings of patients with HOD. METHODS: Sixteen patients (8 female and 8 male) with a mean age of 40.7 years, (range, 5-83 years) years were included in this study based on clinical symptoms and MRI findings. RESULTS: We reviewed the clinical and imaging findings in 16 cases of HOD at our institution. Seven patients (43.7%) had posterior fossa tumors, 6 patients (37.5%) had cavernoma, 2 patients (12.5%) sustained traumatic brain injury, and only 1 patient (6.2%) had cerebellar infarction. Posterior fossa surgery was performed in 13 (81.2%) of these patients. HOD was detected a mean of 7.2 months (range, 0.5-18 months) after surgery or primary neurologic insult. Unilateral HOD was observed in 10 patients (62.5%), while bilateral HOD was observed in only 6 patients (37.5%). Seven patients (43.7%) were asymptomatic for HOD, whereas 5 patients (31.2%) had symptoms attributable to HOD. Two patients died because of primary tumors, although mean follow-up after detection of HOD on MRI was 52.2 months (range, 1-120 months) in the remaining 14 patients. In these cases, no change in clinical symptoms or imaging findings was detected during follow-up. CONCLUSIONS: In this series, posterior fossa tumors and cavernomas were the most common causes of HOD. Although most of the patients with HOD remained asymptomatic, HOD complicated the course of recovery in almost one quarter of the patients included in this study. Neurosurgeons should be aware of HOD, which has characteristic clinical and imaging findings. In addition, HOD can complicate the recovery of patients with disruption to the dentato-rubro-olivary tract.

Emergency resection of brainstem cavernous malformations.

Brainstem cavernous malformations (CMs) pose significant challenges to neurosurgeons because of their deep locations and high surgical risks. Most patients with brainstem CMs present with sudden-onset cranial nerve deficits or ataxia, but uncommonly patients can present in extremis from an acute hemorrhage, requiring surgical intervention. However, the timing of surgery for brainstem CMs has been a controversial topic. Although many authors propose delaying surgery into the subacute phase, some patients may not tolerate waiting until surgery. To the best of the authors' knowledge, emergency surgery after a brainstem CM hemorrhage has not been described. In cases of rapidly progressive neurological deterioration, emergency resection may often be the only option. In this retrospectively reviewed small series of patients, the authors report favorable outcomes after emergency surgery for resection of brainstem CMs.

Overcoming End-to-End Vessel Mismatch During Superficial Temporal Artery-Radial Artery-M2 Interposition Grafting for Cerebral Ischemia: Tapering Technique.

Cerebral revascularization procedures, such as the external carotid-internal carotid bypass, have been used in the clinical management of cerebral ischemic states. Among the most commonly performed bypasses is the superficial temporal artery-middle cerebral artery (STA-MCA) bypass to restore cerebral blood flow. In cases of a foreshortened STA donor vessel, a radial artery (RA) graft is often used as an interposition graft between the STA and MCA. However, addressing the vessel size mismatch between the radial artery and donor can be problematic and challenging. We present the case of an 80-year-old male presenting with positional-onset expressive aphasia and right-sided hemiparesis. Computed tomography perfusion demonstrated a diffusion-perfusion mismatch in a left MCA distribution. Angiography showed a complete left internal cerebral artery occlusion and poor distal filling of the STA. We performed an external carotid artery-to-internal carotid artery bypass through interposing an RA graft to the STA proximally with an end-to-end anastomosis and to the MCA distally using an end-to-side anastomosis. The mismatch between 2 bypass vessel sizes was corrected by removing a small piece from the RA graft at 1 margin and suturing it to itself to reduce the size of the RA vessel diameter opening on the side used to sew to the STA. The patient did well clinically with improved right-sided strength, a patent graft, and no postoperative complications. Addressing vessel mismatch when using RA interposition grafts for bypass is challenging. Various operative approaches to address mismatch should be individualized on the basis of the particular vascular anatomy and needs of the case. Nevertheless, our method of cutting and suturing 1 side of the RA graft into a semiblind end to match donor vessel diameter may be of use to cerebrovascular surgeons in select cases.

Minimizing Retraction by Pia-Arachnoidal 10-0 Sutures in Intrasulcal Dissection.

BACKGROUND: In contemporary microneurosurgery reducing retraction-induced injury to the brain is essential. Self-retaining retractor systems are commonly used to improve visualization and decrease the repetitive microtrauma, but sometimes self-retaining retractor systems can be cumbersome and the force applied can cause focal ischemia or contusions. This may increase the morbidity and mortality. Here, we describe a technique of retraction using 10-0 sutures in the arachnoid. OBJECTIVE: To evaluate the imaging and clinical results in patients where 10-0 suture retraction was used to aid the surgical procedure. METHODS: Adjacent cortex was retracted by placing 10-0 nylon suture in the arachnoid of the bank or banks of the sulcus. The suture was secured to the adjacent dural edge by using aneurysm clips, allowing for easy adjustability of the amount of retraction. We retrospectively analyzed the neurological outcome, signal changes in postoperative imaging, and ease of performing surgery in 31 patients with various intracranial lesions including intracranial aneurysms, intra- and extra-axial tumors, and cerebral ischemia requiring arterial bypass. RESULTS: Clinically, there were no injuries, vascular events, or neurological deficits referable to the relevant cortex. Postoperative imaging did not show changes consistent with ischemia or contusion due to the retraction. This technique improved the visualization and illumination of the surgical field in all cases. CONCLUSION: Retraction of the arachnoid can be used safely in cases where trans-sulcal dissection is required. This technique may improve initial visualization and decrease the need for dynamic or static retraction.

Metastatic prostate adenocarcinoma to intradural foramen magnum.

Intradural metastatic tumors are rarely reported in foramen magnum (FM), including cases of melanoma, pituitary carcinoma, thyroid carcinoma, and prostate carcinoma metastases. We report a 68-year-old male who presented with right-sided headache, progressive swallowing difficulty requiring gastrostomy tube and hoarseness over the course of 1 year. Images revealed a heterogeneous, contrast-enhancing lesion in the FM that compressed the anterior aspect of the medulla and upper spinal cord. Although metastatic tumor was considered in differential diagnosis, presumptive diagnosis was FM meningioma due to lack of bone destruction or sclerosis on CT and T2W isointense and T1W hypointense appearance on MRI. The patient underwent gross total resection via right far-lateral transcondylar approach. Histopathological examination revealed prostate carcinoma metastasis. To the best of our knowledge this is the second case report of an intradural prostate carcinoma metastasis in the FM.