Ventriculoperitoneal shunt infection and malfunction in adult patients: incidence, risk factors, and long-term follow-up of single institution experience.

Ventriculoperitoneal shunt surgery was developed to manage excessive cerebrospinal fluid (CSF) in the brain's ventricles and is considered a mainstream treatment. Despite the development of the shunt device system, various complications still occur. In this study, we reported 307 cases and a long-term follow-up of at least five years of adult patients who underwent VP shunt surgery and analyzed various factors that may affect revision surgery. A retrospective study was conducted at Asan Medical Center, Korea, a tertiary medical center. We reviewed 307 cases from January 2012 to December 2018. The patients' neurological status, predisposing medical conditions, laboratory findings, and other operation-related factors were reviewed using electrical medical records. The normal function group comprised 272 cases (88.6%), and the overall incidence of revision group comprised 35 cases (11.4%). Of the 35 revision surgery cases, 30 (85.71%) were due to shunt malfunctions, such as obstruction, overdrainage, and valve-related errors while 5 (14.29%) were due to shunt infection. Patient demographics, mental status, and operation time did not influence revision as risk factors. Serum laboratory findings showed no statistical difference between the two groups. The white blood cell (WBC) count in the CSF profile differed significantly between the two groups. The Hakim Programmable valve (Codman, USA) is mainly used in our center. In addition, various shunt systems were used, including Strata Regulatory valve (Medtronic, USA), proGAV (Aesculap, USA), and Accu-Flo (Codman, USA). This study analyzed the factors affecting long-term outcomes. Based on these findings, efforts are needed to achieve more favorable outcomes in the future.

Long-term outcome followed for more than 5 years after revascularization surgery for the treatment of atherosclerotic steno-occlusive disease: poor outcome prediction using machine learning and analysis of the results.

Cerebral revascularization for the treatment of atherosclerotic steno-occlusive disease (ASOD) was found to have no benefit compared with medical treatment. However, there is also criticism that with sufficiently long-term follow-up, a crossover might emerge demonstrating the advantages of surgery. Therefore, we examined the long-term outcome of cerebral revascularization performed on patients with carefully selected ASOD at our center. Patients undergoing bypass surgery for non-moyamoya ischemic disease were retrospectively identified. The inclusion criteria were symptomatic ASOD with hemodynamic insufficiency, follow-up of more than 5 years, and stroke or surgical complications during follow-up. The clinical course and radiological findings were investigated. Poor outcomes were predicted using machine learning (ML) models, and Shapley additive explanation (SHAP) values and feature importance of each model were analyzed. A total of 109 patients were included from 2007 to 2018. The 30-day risk of any stroke or death was 6.4% (7/109). The risk of ipsilateral ischemic stroke during median follow-up of 116 months was 7.3% (8/109). The SHAP values showed that previously and empirically known stroke risk factors exert a relatively consistent effect on the prediction of models. The number of lesions with stenosis > 50% (odds ratio [OR] 5.77), age (OR 1.13), and coronary artery disease (OR 5.73) were consistent risk factors for poor outcome. We demonstrated an acceptable long-term outcome of cerebral revascularization surgery for patients with hemodynamically insufficient and symptomatic ASOD. Multicenter studies are encouraged to predict poor outcomes and suitable patients with large numbers of quantitative and qualitative data.

Risk of Cerebral Aneurysm Rupture After Liver Transplantation: Development and Validation of a Hemorrhagic Stroke Scoring Model.

BACKGROUND: Liver transplantation (LT) patients appear to be more prone to neurological events compared to individuals undergoing other types of solid-organ transplantation. The aims of the present study were to analyze the prevalence of unruptured intracranial aneurysms (UIAs) in patients undergoing liver transplantation (LT) and to examine the perioperative occurrence of subarachnoid hemorrhage (SAH). Also, it intended to systematically identify the risk factors of SAH and hemorrhagic stroke (HS) within a year after LT and to develop a scoring system which involves distinct clinical features of LT patients. METHODS: Patients who underwent LT from January 2012 to March 2022 were analyzed. All included patients underwent neurovascular imaging within 6 months before LT. We conducted an analysis of prevalence and radiological features of UIA and SAH. The clinical factors that may have an impact on HS within one year of LT were also reviewed. RESULTS: Total of 3,487 patients were enrolled in our study after applying inclusion and exclusion criteria. The prevalence of UIA was 5.4%. The incidence of SAH and HS within one year following LT was 0.5% and 1.6%, respectively. We developed a scoring system based on multivariable analysis to predict the HS within 1-year after LT. The variables were a poor admission mental status, the diagnosis of UIA, serum ammonia levels, and Model for End-stage Liver Disease (MELD) scores. Our model showed good discrimination among the development (C index, 0.727; 95% confidence interval [CI], 0.635-0.820) and validation (C index, 0.719; 95% CI, 0.598-0.801) cohorts. CONCLUSION: The incidence of UIA and SAH was very low in LT patients. A poor admission mental status, diagnosis of UIA, serum ammonia levels, and MELD scores were significantly associated with the risk of HS within one year after LT. Our scoring system showed a good discrimination to predict the HS in LT patients.

Treatment strategies for dissecting aneurysms of the posterior cerebral artery.

BACKGROUND: Dissecting aneurysms of the posterior cerebral artery (PCA) are rare and difficult to treat because of their deep and unfamiliar locations and unusual shapes. Although several treatment modalities have been proposed, none have generated satisfying results. Our experiences with PCA-dissecting aneurysms are reviewed and the treatment strategies discussed. METHODS: All consecutive patients with PCA-dissecting aneurysm who were treated in a tertiary referral hospital between January 1998 and March 2014 were identified by retrospective review. Their clinical characteristics, radiological findings, treatment modalities and outcomes were documented. RESULTS: Of the 21 patients with 21 PCA-dissecting aneurysms, 9 had subarachnoid hemorrhage and 3 had acute infarction of the thalamus at presentation. The aneurysms involved P1 (n = 4), the P1-2 junction (n = 3), mid-P2 (n = 6), P2A (n = 3), P2P (n = 1) and the P2-3 junction (n = 4). The aneurysm shapes were as follows: fusiform (n = 12), partially thrombosed (n = 8) and blood blister-like aneurysms (n = 1). The mean size was 16.6 ± 9.7 mm. Parent artery occlusion (PAO) without bypass (n = 15), PAO with bypass (n = 2), stent-assisted endosaccular coiling (n = 3) and stent placement only (n = 1) were performed. All three patients who underwent stent-assisted endosaccular coiling and the single patient who underwent PAO without bypass developed aneurysm recurrence. Six of the ten patients who received a PAO without a balloon test occlusion (BTO) experienced PCA territory infarction, whereas only one of the five patients who received a PAO after passing the BTO experienced an infarction. CONCLUSIONS: PAO for PCA-dissecting aneurysm was effective in preventing recurrence. In addition, BTO before PAO was helpful in identifying candidates who truly needed surgical revascularization.

Results of re-exploration because of compromised distal blood flow after clipping unruptured intracranial aneurysms.

BACKGROUND: One of the major causes for performing unplanned re-exploration of a craniotomy after microsurgery for unruptured intracranial aneurysms (UIAs) is compromised distal blood flow after clipping. Therefore, it is important to identify the causes of compromised distal blood flow after clipping and the factors that influence the prognosis for re-exploration in order to decrease ischemic complications related to clipping UIAs. METHOD: Between January 2007 and December 2013, 1954 patients underwent microsurgery for UIAs. In this cohort, 20 patients (1.0%) required unplanned re-exploration of the craniotomy for several reasons, and 11 patients (0.6%) underwent unplanned re-exploration with clip repositioning or changing of the previous clip because of compromised distal blood flow after clipping. Patient characteristics, aneurysm properties, intraoperative findings, annual incidence and prognosis were analyzed in these 11 patients. RESULTS: The annual incidence of re-exploration has gradually decreased since the introduction of several intraoperative monitoring techniques. In total, 3.0% of UIAs in the M1 trunk, 0.8% of UIAs at the origin of the anterior choroidal artery (AchA) and 0.5% of UIAs at the bifurcation of the middle cerebral artery (MCA) required re-exploration. Here, all 11 UIAs had broad necks, and atherosclerosis was identified around 10 UIAs. Six patients with compromised MCA flow demonstrated relatively better outcomes following re-exploration than five patients with a compromised lenticulostriate artery (LSA) or AchA flow. Four patients with delayed ischemic symptoms demonstrated relatively better outcomes than the seven patients who developed ischemic symptoms immediately postoperatively. CONCLUSION: Clinicians need to be more careful not to compromise distal blood flow when clipping UIAs at the MCA and AchA origin. Various intraoperative monitoring techniques can help reduce the incidence of compromised distal blood flow after clipping.

Adenosine-induced transient asystole during intracranial aneurysm surgery: indications, dosing, efficacy, and risks.

BACKGROUND: Several flow-arrest techniques have been introduced for the treatment of complex aneurysms that cannot be treated with conventional clipping or endovascular coil embolization. Adenosine-induced transient asystole is an alternative method of flow arrest. However, given the limited number of studies that have reported on this topic, there is no consensus regarding the dose, regimen, efficacy, and potential risks of adenosine. METHOD: A total of 22 aneurysms in 22 different patients that underwent adenosine-induced transient asystole during aneurismal neck clipping within the past 4 years were retrospectively reviewed. Adenosine was administrated intravenously in a test-incremental manner (starting with 6-12 mg and then giving additional doses as needed) in 11 patients and in an estimated manner (pre-calculated as 0.3-0.4 mg/kg) in 11 patients. RESULTS: Overall, the study consisted of 18 unruptured saccular aneurysms, three ruptured saccular aneurysms, and a ruptured pseudoaneurysm. Adenosine-induced transient asystole was used in cases of temporary clipping inability, wide necked aneurysm, deep-seated aneurysm, or a thin aneurysm wall. The number of administrations, dose (mg/kg in ideal body weight) and duration of asystole were 1-4 (mean, 2.3) times, 0.08-1.27 (mean, 0.36) mg/kg and 0-30 (mean 13) seconds in the test-incremental manner and 1-2 (mean, 1.09) times, 0.24-0.42 (mean, 0.34) mg/kg and 13-41 (mean, 24) seconds in the estimated manner, respectively. There was a linear relationship between the dose and the duration of asystole. Twenty out of 22 aneurysms were clipped successfully with adenosine-induced transient asystole. However, in the other two cases, additional suction decompression was required for the final clipping. Adenosine-related cardiologic complications occurred in two cases of self-limited atrial fibrillation during restoration of the cardiac rhythm. CONCLUSIONS: In our experience, adenosine-induced transient asystole was safe and helpful for satisfactory clipping of a complicated aneurysm. An estimated dose injection of adenosine was more convenient than the test-incremental method and did not result in serious cardiologic problems.

Re-exploration of the craniotomy after surgical treatment of unruptured intracranial aneurysms.

BACKGROUND: Unplanned re-exploration of the craniotomy after surgical treatment of unruptured intracranial aneurysms (UIAs) is sometimes required, but the underlying causes and rates of these procedures are seldom reported. This study retrospectively analyzed the causes of such re-explorations to identify methods for decreasing their necessity. METHOD: From January 2000 to December 2011, 1,720 patients with a total of 1,938 UIAs underwent surgical treatment at our institution. From this cohort, 26 patients (1.5 %) with 38 UIAs required re-exploration. Clinical data, aneurysm characteristics, treatment methods, and the incidence and causes of re-exploration of the craniotomy were analyzed for these 26 patients. RESULTS: Several causes of re-exploration were identified: compromised distal blood flow (eight patients, 0.47 %), hemorrhagic venous infarction (four patients, 0.23 %), brain retraction injury (three patients, 0.17 %), newly identified aneurysms (three patients, 0.17 %), bleeding from an incompletely clipped aneurysm (two patients, 0.12 %), epidural hematoma (two patients, 0.12 %), failed aneurysm clipping (two patients, 0.12 %) and other causes (two patients, 0.12 %). Annual re-exploration incidence rates ranged from 0 to 3.1 %. Annual incidence rates gradually decreased following the introduction of several intraoperative monitoring systems. CONCLUSIONS: Precise surgical planning and careful operative techniques can reduce the incidence of unplanned re-exploration of the craniotomy. The introduction of various intraoperative monitoring systems can also contribute to a reduction in this incidence.

Characteristics and outcomes of varied treatment modalities for partially thrombosed intracranial aneurysms: a review of 35 cases.

OBJECTIVE: The purpose of this study was to analyze the characteristics of partially thrombosed intracranial aneurysms (PTIAs) in terms of location, shape, size, and symptoms, and to assess outcome according to the type of treatment. METHODS: We reviewed the radiological and clinical findings of 35 cases of PTIAs followed in our institution between 2006 and 2011. We divided all treatment modalities into two groups. Patients in group A (n = 15) were treated by blood flow blockage from the lesion of the pathogenic segment of the parent where the PTIAs originated, and patients in group B (n = 20) were only treated with obliteration of the remnant perfused aneurysmal sac. Radiological and clinical outcomes of treatment were compared between the two groups. RESULTS: Group A showed complete occlusion in 15 cases (100 %) compared to six cases (30.0 %) in group B (p < 0.001). No cases required retreatment in group A, while six cases (30.0 %) underwent retreatment in group B (p = 0.027). In terms of clinical outcome, 12 cases (80.0 %) showed symptomatic improvement in group A compared to eight cases (40.0 %) in group B (p = 0.037). Nine cases (60.0 %) showed improvement in postoperative GOS at six months compared to initial preoperative GOS in group A versus four (20.0 %) in group B (p = 0.032). CONCLUSION: PTIAs should be treated by preventing blood flow from the lesion of the pathogenic segment of the parent artery where PTIAs originate. This treatment approach is associated with better clinical and radiological outcomes.

Hypertrophic olivary degeneration following surgical resection or gamma knife radiosurgery of brainstem cavernous malformations: an 11-case series and a review of literature.

BACKGROUND: We describe 11 patients with hypertrophic olivary degeneration (HOD) after surgical resection or gamma knife radiosurgery for brainstem cavernous malformations. In addition, we statistically analyzed the predicting factors associated with the development of HOD. METHODS: From January 2001 to May 2011, a total of 73 patients (30 in the surgical group and 43 in the radiosurgery group) with brainstem cavernous malformations were treated in our institute. Of them, 11 patients (incidence: 15 %) developed HOD with high signal intensity on T2-weighted MRI during follow-up. The predicting factors (location, size, age, and treatment method) associated with the development of HOD were statistically analyzed. RESULTS: Among the 11 HOD patients, seven patients received surgical resection and four patients received gamma knife radiosurgery. Six patients had bilateral HOD and the remaining five patients had unilateral HOD. Overall HOD-associated symptoms presented in four patients, including three palatal tremors and one ataxia. In all four patients with symptoms, these symptoms disappeared incompletely within the clinical follow-up period. The size of the cavernous malformation, age of patient, and treatment methods were not significantly correlated with the development of HOD. A significantly higher incidence of HOD was associated with midbrain cavernous malformations than with pontine or medulla cavernous malformations. CONCLUSIONS: HOD should be recognized as a non-infrequent complication of surgical resection or gamma knife radiosurgery within the brainstem, especially for midbrain cavernous malformations. In addition, to the best of our knowledge, this is the first report on HOD development after radiosurgery.

Efficacy of intraoperative neuromonitoring (IONM) and intraoperative indocyanine green videoangiography (ICG-VA) during unruptured anterior choroidal artery aneurysm clipping surgery.

OBJECTIVE: The aim of this study was to investigate the efficacy of intraoperative indocyanine green videoangiography (ICG-VA) and intraoperative neuromonitoring (IONM) to prevent postoperative ischemic complications during microsurgical clipping of unruptured anterior choroidal artery (AChA) aneurysms. METHODS: We retrospectively reviewed the clinical and radiological records of all patients who had undergone microsurgical clipping for unruptured AChA aneurysms at our institution between April 2001 and December 2019. We compared the postoperative complication rate of the group for which intraoperative ICG-VA and IONM were utilized (group B; n=324) with that of the group for which intraoperative ICG-VA and IONM were not utilized (group A; n=72). RESULTS: There were no statistically significant differences in demographic data between the two groups. Statistically significant differences were observed in the rate of overall complications (p=0.014) and postoperative ischemic complications related to AChA territory (p=0.039). All the cases (n=4) in group B who had postoperative infarctions related to AChA territory showed false-negative results of intraoperative ICG-VA and IONM. CONCLUSIONS: Preserving the patency of the AChA is essential to minimize postoperative complications. Intraoperative monitoring tools including ICG-VA and IONM can greatly contribute to lowering complication rates. However, their pitfalls and false-negative results should always be considered.

Clipping of Unruptured Anterior Choroidal Artery Aneurysms Together with Small Branches: Safety Confirmation Using Intraoperative Indocyanine Green Video-Angiography and Intraoperative Neurophysiological Monitoring.

BACKGROUND: In treating anterior choroidal artery (AChA) aneurysms, preserving the AChA main trunk is of course necessary to prevent postoperative ischemic complications. However, in practice, complete occlusions are often limited by small branches. OBJECTIVE: We aimed to demonstrate that even in cases where complete occlusion of the AChA aneurysm is complex due to small branches, complete occlusion can be safely achieved using indocyanine green video-angiography and intraoperative neurophysiological monitoring (IONM). METHODS: We performed a retrospective review of all unruptured AChA aneurysms surgically treated at our institution from 2012 to 2021. All available surgical videos were reviewed to find AChA aneurysms clipped with small branches; clinical and radiological data were collected for these cases. RESULTS: Among 391 cases of unruptured AChA aneurysms treated surgically, 25 AChA aneurysms were clipped with small branches. AChA-related ischemic complications occurred in 2 cases (8%) without retrograde indocyanine green filling to the branches. These 2 cases had changes in IONM. There were no ischemic complications in the remaining cases with retrograde indocyanine green filling to the branches and no change in IONM. During an average follow-up of 47 months (12-111 months), a small residual neck was observed in 3 cases (12%) and recurrence or progression of the aneurysm was observed in only 1 case (4%). CONCLUSIONS: The surgical treatment of AChA aneurysms carries the risk of devastating ischemic complications. Even in cases where complete clip ligation seems impossible due to small branches associated with AChA aneurysms, complete occlusion can be safely achieved using indocyanine green video-angiography and IONM.

Superficial temporal artery interposition bypass for the treatment of complex intracranial aneurysms: Flexible and creative options for flow preservation bypass.

PURPOSE: Flow-preservation bypass is a treatment option for complex intracranial aneurysms (IAs) that cannot be managed with microsurgical clipping or endovascular treatment. Various bypass methods are available, including interposition grafts such as the radial artery or saphenous vein. Size discrepancy, invasiveness, and procedure complexity must be considered when using interposition grafts. We describe our experience of treating complex IAs using a superficial temporal artery (STA) interposition bypass. METHODS: We retrospectively reviewed the medical records and operative videos of all patients who were treated for complex IAs at our center from January 2009 to December 2021 using cerebral revascularization. Clinical, radiological, and surgical findings of the cases that underwent STA interposition bypass were investigated. RESULTS: Seventy-six bypass procedures were performed of which seven (9.2%) complex IAs were managed using STA interposition bypass. Of these 5 cases were of anterior cerebral artery, 1 of middle cerebral artery, and 1 of posterior inferior cerebellar artery aneurysm. There were no postoperative ischemic complications. Revision surgery for postoperative pseudomeningocele was performed in one case. The long-term bypass patency rate was 85.7% (6 out of 7) and good long-term aneurysm control was achieved in all cases, with a mean follow-up of 64 months. CONCLUSIONS: When treating complex IAs, creative revascularization strategies are needed in selective cases for favorable outcomes. STA interposition graft bypass which can reduce the size discrepancy between the donor and recipient may be a less invasive, flexible, and practical option for treating complex IAs.

Moyamoya disease-related versus primary intracerebral hemorrhage: [corrected] location and outcomes are different.

BACKGROUND AND PURPOSE: The purpose of our study was to compare lesion location between moyamoya disease-related intracerebral hemorrhage (MMD-ICH) and primary intracerebral hemorrhage (P-ICH). METHODS: Ninety-three patients each with MMD-ICH and P-ICH were compared. In patients with MMD-ICH, angiographic findings were assessed with special attention to the prominent anterior choroidal artery. Follow-up data were obtained through clinical visit and telephone interview. RESULTS: The location of hemorrhage was different between MMD-ICH and P-ICH, the most frequent one being intraventricular region (37.6%) in the former and putaminal region (46.2%) in the latter (P<0.001). Intraventricular hemorrhage was more frequent in MMD-ICH than P-ICH (80.6% versus 20.4%, P<0.001). In MMD-ICH, primary intraventricular hemorrhage was more closely associated with prominent ipsilateral anterior choroidal artery than ICHs without intraventricular hemorrhage (75.0% versus 16.7%, P<0.001). Higher rates of rebleeding and infarction were observed in MMD-ICH than in age- and sex-matched patients with P-ICH. CONCLUSIONS: MMD-ICH may differ from P-ICH in hemorrhage location, generally presenting with intraventricular hemorrhage with or without ICH, which may be due to a prominent anterior choroidal artery. Patients with MMD may be more likely to experience recurrent bleeding and infarction.

STA-ACA bypass using the contralateral STA as an interposition graft for the treatment of complex ACA aneurysms: report of two cases and a review of the literature.

Bypass surgery has been used as a remedy for the complex cerebral aneurysm, which was unsolved with the clipping method. However, little has been reported about bypass options for anterior cerebral artery (ACA) aneurysms. The authors experienced two patients with complex ACA aneurysms, large fusiform and large thrombosed aneurysms involving the distal A1 and proximal A2 segments, respectively. To achieve complete obliteration of the aneurysm, we performed a superficial temporal artery (STA)-ACA bypass using contralateral STA as interposition grafts with endovascular trapping without any ischemic events. These cases show that STA-ACA bypass using contralateral STA interposition graft is a feasible option to maintain blood supply to the ACA territory if a proximal ACA lesion requires trapping.

Comparison of Visual Outcomes of Ophthalmic Artery Aneurysms Treated with Microsurgical Clipping and Endovascular Coiling.

PURPOSE: Post-treatment visual deficit is a major concern associated with both microsurgical clipping and endovascular coiling for the treatment of ophthalmic artery (OphA) aneurysms of the internal carotid artery. We aimed to compare the safety and effectiveness of the 2 modalities. MATERIALS AND METHODS: We retrospectively reviewed and compared the baseline characteristics and postoperative visual and angiographic outcomes of OphA aneurysms treated by clipping or coiling between January 2010 and August 2018 at our hospital. In addition, the balloon occlusion test was performed to evaluate the safety of OphA occlusion. RESULTS: This study included 56 aneurysms treated by clipping and 82 aneurysms treated by coiling. Both the immediate and follow-up rates of incomplete aneurysm occlusion were comparable between the 2 groups (21.4% vs. 22.0%; 24.4% vs. 23.6%). The incidence of post-treatment visual deficits was higher in the clipping group than in the coiling group (16.1% vs. 2.4%; P=0.010). We observed total ipsilateral OphA occlusion in 6 patients and near occlusion in 3 patients during endovascular coiling; however, only 1 patient with near OphA occlusion showed a post-treatment visual field defect. CONCLUSION: OphA aneurysms treated by endovascular coiling exhibited an aneurysm occlusion rate similar to that of microsurgical clipping with fewer post-treatment visual deficits. The total occlusion of OphA with adequate collaterals did not cause post-treatment visual deficits.

Salvage techniques for STA-MCA bypass.

Superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass is a well-established, indispensable neurosurgical procedure. It is technically challenging, and surgeons must be prepared for unexpected problems. The present report describes four cases where problems arose that resulted in graft occlusion. None of these problems was directly related to the anastomosis procedure, and they occurred from early in the operation (e.g., STA preparation) to late (e.g., skin closure). In all cases, the salvage procedures used were successful, and postoperative angiography demonstrated good bypass patency.

Role of microsurgery for treatment of posterior circulation aneurysms in the endovascular era.

OBJECTIVE: Several studies have reported that the outcomes of endovascular treatment were superior to those of microsurgical treatment for posterior circulation aneurysms. Thus, this study compared outcomes of endovascular and microsurgical treatment for posterior circulation aneurysms and assess the usefulness of microsurgery in these patients. METHODS: Outcomes were retrospectively evaluated after endovascular and microsurgical treatment of 621 posterior circulation aneurysms. The 621 aneurysms included 187 treated by surgical clipping and 434 treated by endovascular coiling. RESULTS: In patients with unruptured aneurysms the rates of residual lesions and retreatment were significantly lower in those who underwent microsurgical than endovascular treatment. However immediate postoperative and 6 month follow-up Glasgow outcome scale (GOS) scores did not differ significantly in the two groups. In patients with ruptured aneurysms, the rates of residual lesions and retreatment were significantly lower in the microsurgery than in the endovascular treatment group. Even so immediate postoperative and 6 month follow-up GOS scores did not differ significantly in the two groups. CONCLUSIONS: Endovascular treatment has increasingly become an alternative modality for microsurgery in posterior circulation aneurysm, whereas the indication for microsurgery is greatly reduced. However, the absolute number of microsurgery is maintained showing that it is a still valuable technique, as advances in endovascular or stent-assisted coiling have not solved many of the challenges inherent in the management of complex aneurysms. Hence, the advantages and limitations of both modalities must be carefully concerned in posterior circulation aneurysm to obtain favorable outcome.

Incidental Microaneurysms During Microvascular Surgery: Incidence, Treatment, and Significance.

BACKGROUND: Although new imaging tools have been developed for the detection of smaller aneurysms, angiographically negative microaneurysms are still encountered during cerebral microsurgery. Currently, only limited information regarding incidence and efficacy of treatment of these microaneurysms is available. METHODS: We investigated the incidence and treatment of incidental microaneurysms (IMAs) in the last 5 years. IMAs are unidentifiable and invisible on preoperative angiography, but are detected during microvascular surgery. The inclusion criteria were aneurysm cases treated with microsurgery via transsylvian approaches, and those undergoing preoperative digital subtraction angiography. RESULTS: This study enrolled 484 surgical cases (248 cases of subarachnoid hemorrhage and 236 cases of unruptured aneurysms) in 460 patients, and 33 tiny aneurysms were found in 31 operative cases (6.4% incidence per operation). The most typical type was located on another branching site of the middle cerebral artery found during neck clipping of the middle cerebral artery bifurcation aneurysm. A patient with multiple aneurysms presented a statistically significant risk (375/78 vs. 15/16; P < 0.001) of IMA identification. IMAs were treated by clipping and wrapping in 18 and 15 cases, respectively, without complications. CONCLUSIONS: This study revealed a 6.4% incidence of IMAs; however, this could be underestimated because of the limited range of inspection. Early detection of an IMA through careful inspection during microvascular surgery could be beneficial, especially in patients with multiple aneurysms.

Characteristics of Peri-Internal Carotid Artery Bifurcation Aneurysms According to a New Anatomic Classification: How to Overcome Difficulties in the Microsurgical Treatment of Posteroinferiorly Projecting Carotid-A1 Junctional Aneurysms.

OBJECTIVE: Based on our clinical experience, posteroinferiorly projecting carotid-A1 junctional aneurysms are often difficult to treat microsurgically. Our objective was to classify peri-internal carotid artery (ICA) bifurcation aneurysms according to their location and analyze their characteristics. METHODS: From January 2008 to October 2017, microsurgical or endovascular treatment of 6777 aneurysms were performed at our hospital. We identified 199 peri-ICA bifurcation aneurysms (2.94%) classified into true ICA bifurcation aneurysm, carotid-A1 junctional aneurysm, and carotid-M1 junctional aneurysm according to the anatomic location. Medical records including patient characteristics, aneurysm location, surgical method, any neurologic deficits, clinical outcomes, medical history, and radiologic findings were retrospectively reviewed. The anatomic position of the aneurysm was defined from the virtual surgical, anteroposterior, and lateral views, and the degree of agreement was calculated. RESULTS: There were 103 true ICA bifurcation aneurysms, 92 carotid-A1 junctional aneurysms, and 4 carotid-M1 junctional aneurysms. Carotid-A1 junctional aneurysms tended to be smaller, elongated, and more often posteroinferiorly projecting than true ICA bifurcation aneurysms. Posteroinferiorly projecting carotid-A1 junctional aneurysms tended to require complex aneurysm surgery. The virtual surgical view had an almost perfect degree of agreement with the actual surgical view. CONCLUSIONS: The characteristics of carotid-A1 junctional aneurysms and true ICA bifurcation aneurysms differ. In particular, carotid-A1 junctional aneurysms tend to have a posteroinferior projection and that causes difficulty in surgical treatment. We recommend the virtual surgical view for preoperative planning. Furthermore, an adequate Sylvian fissure opening and a strategic approach using appropriate devices to inspect blind spots should be considered for a successful treatment outcome.

Microsurgical treatment strategy for large and giant aneurysms of the internal carotid artery.

OBJECTIVE: We aimed to summarize our microsurgical treatment results for large (10-25 mm) and giant (≥25 mm) intradural internal carotid artery (ICA) aneurysms over a 7-year period at a single institution and to describe our detailed strategy. PATIENTS AND METHODS: We reviewed the records of 68 patients with 69 aneurysms, including large and giant intradural ICA aneurysms, treated using microsurgical techniques from January 2008 to December 2014. We used adenosine-induced cardiac standstill or retrograde suction decompression for some aneurysm clipping cases and performed bypass surgery if needed. RESULTS: Fifty-eight large and giant ICA aneurysms (84%) were treated with direct clipping, including 6 aneurysms (9%) clipped using adenosine-induced cardiac standstill and 10 aneurysms (14%) clipped using suction decompression. Eleven unclippable aneurysms (16%) were trapped with extracranial-intracranial bypass. Good or excellent results (modified Rankin Scale scores 0-2) were obtained in 47 patients with unruptured aneurysms (92%) and in 14 patients with ruptured aneurysms (82%) at the 6-month follow-up. Of 17 patients with visual disturbances before treatment, 11 (65%) had improved vision after surgical treatment. A remnant sac was found in 20 cases (29%) on digital subtraction angiography performed immediately postoperatively. At the median follow-up of 22 months, we encountered 3 recurrent aneurysm cases (5%) among the 58 aneurysms that were followed up. CONCLUSION: Our study demonstrated that microsurgical treatment of large and giant intradural ICA aneurysms remains competitive to flow-diverting treatment, if the surgeon is prepared to perform multifarious surgical methods, including adenosine administration, retrograde suction decompression, and bypass vascular anastomosis.