Alfred P. See

The role of regulatory T cells and microglia in glioblastoma-associated immunosuppression

Cell-mediated suppression of anti-tumor immunity is multifactorial in patients with cancer, and recent studies have focused on several distinct cellular agents that are associated with this phenomenon. This review will focus on the potential role of regulatory T cells (Tregs) and microglia in the suppression of cellular immunity observed in patients with glioblastoma. We discuss the ontogeny, basic biology, evidence for activity, and potential clinical options for targeting Tregs and microglia as part of immunotherapy in affected patients.

Stent deployment protocol for optimized real-time visualization during endovascular neurosurgery

Successful application of endovascular neurosurgery depends on high-quality imaging to define the pathology and the devices as they are being deployed. This is especially challenging in the treatment of complex cases, particularly in proximity to the skull base or in patients who have undergone prior endovascular treatment. The authors sought to optimize real-time image guidance using a simple algorithm that can be applied to any existing fluoroscopy system. Exposure management (exposure level, pulse management) and image post-processing parameters (edge enhancement) were modified from traditional fluoroscopy to improve visualization of device position and material density during deployment. Examples include the deployment of coils in small aneurysms, coils in giant aneurysms, the Pipeline embolization device (PED), the Woven EndoBridge (WEB) device, and carotid artery stents. The authors report on the development of the protocol and their experience using representative cases. The stent deployment protocol is an image capture and post-processing algorithm that can be applied to existing fluoroscopy systems to improve real-time visualization of device deployment without hardware modifications. Improved image guidance facilitates aneurysm coil packing and proper positioning and deployment of carotid artery stents, flow diverters, and the WEB device, especially in the context of complex anatomy and an obscured field of view.

Risk factors for hyponatremia in aneurysmal subarachnoid hemorrhage

Hyponatremia occurs commonly in patients with aneurysmal subarachnoid hemorrhage (aSAH). Our objective was to determine the time course of, and factors associated with, hyponatremia after aSAH. We performed a retrospective review of 259 patients with ruptured aneurysms at a single institution. Multivariate regression analysis was performed to determine the factors associated with hyponatremia. Increasing age was significantly associated with lower initial sodium (p=0.04) and incidence of delayed hyponatremia (p=0.01) while smoking was associated with longer duration of hyponatremia (p=0.02). Older patients should therefore be monitored closely for hyponatremia and patients who smoke should be treated more aggressively for hyponatremia given the greater frequency and longer duration of hyponatremia in these two groups, respectively.

Refinement of the Hybrid Neuroendovascular Operating Suite: Current and Future Applications

OBJECTIVE In early-generation hybrid biplane endovascular operating rooms, switching from surgical to angiographic position is cumbersome. In this report, we highlight the unique design of a new hybrid neuroendovascular operating suite that allows surgical access to the head while keeping the biplane system over the lower body of the patient. Current and future hybrid neuroendovascular operating suite applications are discussed. METHODS We collaborated with engineers to implement the following modifications to the design of the angiographic system: translation of the bed toward the feet to allow biplane cerebral imaging in the head-side position and the biplane left-side position; translation of the base of the A-plane C-arm away from the feet to allow increased operator space at the head of the bed and to allow cerebral imaging in both the head-side and left-side positions; use of a specialized boom mount for the display panel to increase mobility; and use of a radiolucent tabletop with attachments for the headrest or radiolucent head clamp system. RESULTS The modified hybrid neuroendovascular operating suite allows for seamless transition between surgical and angiographic positions within seconds, improving workflow efficiency and decreasing procedure time as compared with early-generation hybrid rooms. CONCLUSIONS Combined endovascular and surgical applications are facilitated by co-locating their respective technologies and refining the ergonomics of the system to ease transition between both sets of technologies. In so doing, hybrid neuroendovascular operating suites can be anticipated to improve patient outcomes, generate novel treatment paradigms, and improve time and cost efficiency.

Considerations in Applying a New Stent Retriever in Pediatric Endovascular Cerebral Thrombectomy for Acute Ischemic Stroke.

Acute ischemic stroke (AIS) in children has been difficult to diagnose, treat and study, due to atypical clinical presentation, imaging challenges and the rarity of large-vessel embolic occlusion as the etiology of acute neurological change in children. With endovascular thrombectomy showing success in randomized trials of adult AIS, the technique is increasingly being extrapolated to pediatric stroke. However, there is little evidence regarding the safety or efficacy of applying in children these devices developed and tested in adults. There is concern about a vessel-to-device size mismatch that may result in a different complication and benefit profile than typically seen. We report on the successful application in pediatric stroke of a newer-generation, smaller stent retriever, designed to be delivered through relatively smaller and more navigable microcatheters than the prior generation of this device.

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.

Surgical Treatment of a Double Origin Posterior Inferior Cerebellar Artery Aneurysm and Insights From Embryology: Case Report and Literature Review

BACKGROUND AND IMPORTANCE Aneurysms affecting double origin (DO) posterior inferior cerebellar artery (PICA) variants are rare. Most reports describe endovascular occlusion of the affected branch to treat the aneurysm, but we describe a patient in which open surgical sacrifice of 1 branch resulted in insufficient perfusion. CLINICAL PRESENTATION We report the only case of open surgical treatment of an aneurysm affecting a leg of a DOPICA. A 42-year-old woman presenting with the worst headache of her life was found to have a DOPICA aneurysm and initially treated by trapping the aneurysm. Intraoperative indocyanine green imaging revealed insufficient perfusion through the caudal branch, which was remediated by end-to-end anastomosis to preserve flow through both origins. The patient made a full recovery. CONCLUSION Treating a DOPICA aneurysm by sacrificing 1 of the origins is not possible for all patients. This first report of open surgical treatment of a DOPICA leg aneurysm suggests that 1 or both branches may be required for sufficient perfusion, and the unique embryology of DOPICA development suggests a possible mechanism.

Letter by See et al Regarding Article, “Optimizating Clot Retrieval in Acute Stroke: The Push and Fluff Technique for Closed-Cell Stentrievers”

Haussen et al1 present an interesting series demonstrating an improvement in TICI (Thrombolysis in Cerebral Infarction) 3 revascularization using the push and fluff technique (PFT) for deploying the Trevo Retriever device (Stryker, MI) over standard unsheathing technique. PFT is an interesting technique which seems to be an adaptation of techniques first described in the pipeline embolization device, but there are distinct differences in the response of a braided stent and a closed cell laser-cut stent. The authors propose to increase radial force and clot capture of the stent by increasing coaxial force (pushing and fluffing). Although the authors suggest concerns regarding excessive radial force resulting in arterial rupture, we propose that …

Endovascular Renal Artery Stent Retriever Embolectomy in a Young Patient With Cardiac Myxoma: Case Report and Review of the Literature

Purpose: Cardiac myxomas are common tumors of the heart with disproportionate impact on young patients, occasionally with dramatic systemic dissemination of tumor emboli with catastrophic multiorgan system ischemia. The coincident comorbidities can increase the risk of traditional treatments for tumor embolus in each region. Case report: A young patient with previously unknown cardiac myxoma presented with seizure and was found to have stress cardiomyopathy, multiple cerebral large vessel occlusions with acute ischemic stroke, bilateral lower extremity tumor emboli and rhabdomyolysis, and renal tumor embolus with acute tubular necrosis. We describe a multidisciplinary approach applying cerebrovascular stent retriever devices in tumor embolectomy of the renal artery of a young patient with systemic morbidity, preventing safe laparotomy for open surgical tumor embolectomy. Conclusion: We describe 2-month renal function outcomes and the considerations in applying a neuroendovascular mechanical thrombectomy device within the renal artery. This was a radiographically successful technique and her renal function appears to be improving at the 2-month follow-up, although this is complicated by other renal insults and support.

Comparison of flow diversion with clipping and coiling for the treatment of paraclinoid aneurysms in 115 patients

OBJECTIVEParaclinoid aneurysms represent approximately 5% of intracranial aneurysms (Drake et al. [1968]). Visual impairment, which occurs in 16%-40% of patients, is among the most common presentations of these aneurysms (Day [1990], Lai and Morgan [2013], Sahlein et al. [2015], and Silva et al. [2017]). Flow-diverting stents, such as the Pipeline Embolization Device (PED), are increasingly used to treat these aneurysms, in part because of their theoretical reduction of mass effect (Fiorella et al. [2009]). Limited data on paraclinoid aneurysms treated with a PED exist, and few studies have compared outcomes of patients after PED placement with those of patients after clipping or coiling.METHODSThe authors performed a retrospective analysis of 115 patients with an aneurysm of the cavernous to ophthalmic segments of the internal carotid artery treated with clipping, coiling, or PED deployment between January 2011 and March 2017. Postoperative complications were defined as new neurological deficit, aneurysm rupture, recanalization, or other any operative complication that required reintervention.RESULTSA total of 125 paraclinoid aneurysms in 115 patients were treated, including 70 with PED placement, 23 with coiling, and 32 with clipping. Eighteen (14%) aneurysms were ruptured. The mean aneurysm size was 8.2 mm, and the mean follow-up duration was 18.4 months. Most aneurysms were discovered incidentally, but visual impairment, which occurred in 21 (18%) patients, was the most common presenting symptom. Among these patients, 15 (71%) experienced improvement in their visual symptoms after treatment, including 14 (93%) of these 15 patients who were treated with PED deployment. Complete angiographic occlusion was achieved in 89% of the patients. Complications were seen in 17 (15%) patients, including 10 (16%) after PED placement, 2 (9%) after coiling, and 5 (17%) after clipping. Patients with incomplete aneurysm occlusion had a higher rate of procedural complications than those with complete occlusion (p = 0.02). The rate of postoperative visual improvement was significantly higher among patients treated with PED deployment than in those treated with coiling (p = 0.01). The significant predictors of procedural complications were incomplete occlusion (p = 0.03), hypertension, (p = 0.04), and diabetes (p = 0.03).CONCLUSIONSIn a large series in which patient outcomes after treatment of paraclinoid aneurysms were compared, the authors found a high rate of aneurysm occlusion and a comparable rate of procedural complications among patients treated with PED placement compared with the rates among those who underwent clipping or coiling. For patients who presented with visual symptoms, those treated with PED placement had the highest rate of visual improvement. The results of this study suggest that the PED is an effective and safe modality for treating paraclinoid aneurysms, especially for patients who present with visual symptoms.