Trends in Literature on Cerebral Bypass Surgery: A Systematic Review

<b><i>Introduction:</i></b> Ever since the beginning of cerebral bypass surgery, the role of the bypass has been debated and indications have changed over the last 5 decades. This systematic literature research analysed all clinical studies on cerebral bypass that have been published from January 1959 to January 2020 for their year of publication, country of origin, citation index, role of and indication for bypass, bypass technique, revascularized territory, flow capacity, and title (for word cloud analysis per decade). <b><i>Methods:</i></b> A systematic literature research was conducted using PubMed, Web of Science, EMBASE, and SCOPUS databases. All studies that have been published until January 1, 2020, were included. <b><i>Results:</i></b> Of 6,013 identified studies, 2,585 were included in the analysis. Of these, <i>n</i> = 1,734 (67%) studies addressed flow-augmentation bypass and <i>n</i> = 701 (27%) addressed flow-preservation bypass. The most common indication reported for flow augmentation is moyamoya (<i>n</i> = 877, 51%), followed by atherosclerotic steno-occlusive disease (<i>n</i> = 753, 43%). For flow preservation, the most common indication is studies reporting on cerebral aneurysm surgery (<i>n</i> = 659, 94%). The increasing popularity of reporting on these bypass operations almost came to an end with the FDA approval of flow diverters for aneurysm treatment in 2011. Japan is the country with the most bypass studies (cumulatively published 933 articles), followed by the USA (630 articles) and China (232 articles). <b><i>Discussion/Conclusion:</i></b> Clinical studies on cerebral bypass surgery have become increasingly popular in the past decades. Since the introduction of moyamoya as a distinct pathologic entity, Asian countries in particular have a very active community regarding this disease, with an increasing number of articles published every year. Studies on bypass for chronic steno-occlusive disease peaked in the 1980s but have remained the main focus of bypass research, particularly in many European departments. The number of reports published on these bypass operations significantly decreased after the FDA approval of flow diverters for aneurysm treatment in 2011.

Cerebral Bypass for Aneurysms in the Era of Flow Diversion: Single-Surgeon Case Series

BACKGROUND With recent advances in endovascular treatments of brain aneurysms such as flow diverters, the role of cerebral revascularization needs to be re-evaluated. OBJECTIVE To evaluate the contemporary indications and outcomes of cerebral revascularization for brain aneurysms. METHODS A retrospective evaluation of a prospectively maintained database was performed to review clinical and imaging data of all the patients who underwent cerebral revascularization for brain aneurysms over the past 10 yr. RESULTS Among 174 cerebral revascularizations, 40 (in 36 patients) were done for the treatment of aneurysms. In total, 9 patients underwent combined endovascular treatment and surgical revascularization. Immediate aneurysm occlusion was achieved in 30 patients (83.3%). Immediate postoperative bypass patency was confirmed in 33 patients (92%). Postoperative neurological deficit was observed in 4 patients (11.1%). There were 2 mortalities in the postoperative period. Aneurysm total occlusion rate was 91% at 1 yr. Thirty patients had 1 yr clinical and radiological follow-up. Clinical evaluations showed modified Rankin Scale 2 or less in 25 patients at 1 yr. Bypass patency was confirmed in 27 (90%). Patients with fair/poor outcome were all in the subarachnoid hemorrhage group. Twenty-one patients had follow-up studies for 3 yr or beyond with no evidence of stroke or aneurysm recurrence. CONCLUSION Our results support that cerebral revascularization can be regarded as a viable and durable treatment option for these challenging aneurysms with acceptable morbidity. Cerebral bypass should be offered in selected cases where standard endovascular or surgical treatment is not efficacious or curative.

Gross Total Resection of a Recurrent in-and-around Cavernous Sinus Meningioma through a Combined Transcavernous Anterior and Middle Infratemporal Fossa Approach with Extracranial-Intracranial Bypass

Objectives The study aims to describe surgical management of an invasive cavernous sinus meningioma with a combination of several skull base approaches and bypass surgery. Design This study is an operative video. Results Resection of the recurrent skull base meningioma is still challenging, especially if the tumor involves or encases the carotid artery. Cerebral bypass surgery is an essential adjunct in the armamentarium of skull base surgery when vessel reconstruction is required. In this paper, we describe our experience of successful treatment of an invasive recurrent skull base meningioma, which involved the entire cavernous sinus and the internal carotid artery. A 46-year-old woman presented with a 2-year history of gradually worsening left-sided exophthalmos and visual impairment. The patient had previously undergone two craniotomies for resection of the left-sided spheno-orbital meningioma. Pathological diagnosis was chordoid meningioma, which is classified as an intermediate-grade meningioma. The second surgery had been performed for a rapid tumor regrowth 6 months after the first surgery. The patient lost her left-side vision after the second surgery. Aggressive tumor regrowth was confirmed with extension into the left orbit, infratemporal fossa, and cavernous sinus with engulfment of the carotid artery. A balloon occlusion test revealed intolerance of the left internal carotid artery occlusion. Considering the patient's age, tumor behavior, and intolerance of the carotid artery of the lesion side, we scheduled gross total resection of the tumor with vessel reconstruction. Conclusion Although cerebral bypass surgery is a technically challenging procedure, it plays an important role in the surgical management of the complex vessel-engulfing tumor.The link to the video can be found at https://youtu.be/GCmpxK3hW18.

Pregnancy after direct cerebral bypass for moyamoya disease

OBJECTIVEMoyamoya disease (MMD) disproportionately affects young to middle-aged women. The main treatment for this challenging disease is cerebral bypass surgery. Vascular neurosurgeons often need to counsel women regarding pregnancy following bypass for MMD, but there is a paucity of data. The authors set out to examine neurological and obstetric outcomes in an extensive cohort of MMD patients who had pregnancies following cerebral revascularization at the Stanford Medical Center.METHODSThe authors identified all patients at their institution who underwent cerebral bypass for MMD from 1990 through 2018 and who later became pregnant. Some of these patients also had pregnancies prior to undergoing bypass surgery, and the authors examined these pregnancies as well. They performed a chart review and brief telephone survey to identify obstetric complications, transient ischemic attacks (TIAs), and strokes. Neurological and obstetric outcomes were compared to published rates. They also compared pre- and post-bypass pregnancy complication rates using logistic regression techniques.RESULTSThere were 71 pregnancies among 56 women whose mean age was 30.5 years. Among 59 post-bypass pregnancies, there were 5 (8%) perinatal TIAs. There were no MRI-confirmed strokes or strokes with residual deficits. Among 12 pre-bypass pregnancies, there were 3 (25%) TIAs and 2 (17%) MRI-confirmed strokes. There were no hemorrhagic complications in either group. In the generalized estimating equations analysis, performing cerebral revascularization prior to pregnancy versus after pregnancy was associated with lower odds of perinatal stroke or TIA (OR 0.15, p = 0.0061). Nine pregnancies (13%) were complicated by preeclampsia, and there was one (1%) instance of eclampsia. The overall rate of cesarean delivery was 39%. There were 2 miscarriages, both occurring in the first trimester. There were no maternal deaths.CONCLUSIONSThe authors present neurological and obstetric outcomes data in a large cohort of MMD patients. These data indicate that post-bypass pregnancy is accompanied by low complication rates. There were no ischemic or hemorrhagic strokes among post-bypass pregnant MMD patients. The rate of obstetric complications was low overall. The authors recommend close collaboration between the vascular neurosurgeon and the obstetrician regarding medical management, including blood pressure goals and continuation of low-dose aspirin.

Pregnancy After Cerebral Bypass for Moyamoya Disease

INTRODUCTION Moyamoya disease (MMD) disproportionately affects young to middle age women. Vascular neurosurgeons are often needed to counsel women regarding pregnancy following bypass for MMD, but there is a paucity of data. We set out to examine neurological and obstetric outcomes in an extensive cohort of MMD patients who had pregnancies following cerebral revascularization at the Stanford Medical Center. METHODS We identified all patients who underwent cerebral bypass for MMD and later became pregnant from 1990 through 2018. Some of these patients also had pregnancies prior to bypass, and we examined these pregnancies as well. We performed a chart review and a brief telephone survey to identify obstetric complications, transient ischemic attack (TIA), and stroke. Neurological and obstetric outcomes were compared to published rates. We also compared pre- and postbypass pregnancy complication rates using logistic regression techniques. RESULTS There were 71 pregnancies among 56 women with mean age 30.5. Among 59 postbypass pregnancies, there were 5 (8%) perinatal TIAs. There were no magnetic resonance imaging (MRI) confirmed strokes or strokes with residual deficits. Among 12 prebypass pregnancies, there were 3 (25%) TIAs and 2 (17%) MRI-confirmed strokes. There were no hemorrhagic complications in either group. In the multivariable logistic regression analysis, performing cerebral revascularization prior to pregnancy versus postpregnancy was associated with lower odds of perinatal stroke or TIA (OR 0.13, P = .007). The overall rate of cesarean delivery was 39%. CONCLUSION We present neurological and obstetric outcomes in a large cohort of MMD patients. These data indicate that postbypass pregnancy is accompanied by low complication rates. There were no ischemic or hemorrhagic strokes among postbypass, pregnant MMD patients. Obstetric complications were low overall. We recommend a close collaboration between the vascular neurosurgeon and the obstetrician regarding medical management, including blood pressure goals and continuation of aspirin.