Imaging follow-up strategy after endovascular treatment of Intracranial aneurysms: A literature review and guideline recommendations.

OBJECTIVE: Endovascular coil embolization is the primary treatment modality for intracranial aneurysms. However, its long-term durability remains of concern, with a considerable proportion of cases requiring aneurysm reopening and retreatment. Therefore, establishing optimal follow-up imaging protocols is necessary to ensure a durable occlusion. This study aimed to develop guidelines for follow-up imaging strategies after endovascular treatment of intracranial aneurysms. METHODS: A committee comprising members of the Korean Neuroendovascular Society and other relevant societies was formed. A literature review and analyses of the major published guidelines were conducted to gather evidence. A panel of 40 experts convened to achieve a consensus on the recommendations using the modified Delphi method. RESULTS: The panel members reached the following consensus: 1. Schedule the initial follow-up imaging within 3-6 months of treatment. 2. Noninvasive imaging modalities, such as three-dimensional time-of-flight magnetic resonance angiography (MRA) or contrast-enhanced MRA, are alternatives to digital subtraction angiography (DSA) during the first follow-up. 3. Schedule mid-term follow-up imaging at 1, 2, 4, and 6 years after the initial treatment. 4. If noninvasive imaging reveals unstable changes in the treated aneurysms, DSA should be considered. 5. Consider late-term follow-up imaging every 3-5 years for lifelong monitoring of patients with unstable changes or at high risk of recurrence. CONCLUSIONS: The guidelines aim to provide physicians with the information to make informed decisions and provide patients with high-quality care. However, owing to a lack of specific recommendations and scientific data, these guidelines are based on expert consensus and should be considered in conjunction with individual patient characteristics and circumstances.

Safety of discontinuing antiplatelet therapy 12-24 months after stent-assisted coil embolization: a multicenter retrospective study.

OBJECTIVE: Antiplatelet medication is required after stent-assisted coil embolization (SACE) to avoid thromboembolic complications. Currently, there is no consensus on how long the antiplatelet agent should be maintained. The authors investigated clinical outcomes in patients who discontinued their antiplatelet agent 12-24 months after SACE. METHODS: Data were retrieved from a prospective database for 373 consecutive patients with SACE at 6 institutions who discontinued antiplatelet therapy 12-24 months after SACE. Thromboembolic complications associated with discontinuation were defined as neurological or radiographic ischemia that occurred within 6 months after discontinuation of the antiplatelet agent; the lesion had to be correlated with the territory of the stented artery. RESULTS: The mean time until discontinuation of the antiplatelet medication was 15.8 ± 4.7 months after SACE (12-18 months, n = 271; 19-24 months, n = 102). The most common location of treated aneurysms was the internal carotid artery (n = 223, 59.8%). A laser-cut open-cell stent was most commonly applied (n = 236/388, 60.8%), followed by laser-cut closed-cell stents (n = 119, 30.7%) and braided closed-cell (n = 33, 8.5%); double stenting was applied in 15 aneurysms. There were no patients who experienced cerebral ischemia related to discontinuation of antiplatelet medications, except for 1 patient at high risk of ischemia (0.27%, 95% CI 0.01%-1.48%). CONCLUSIONS: These results suggest that it may be safe to discontinue antiplatelet medication after SACE in patients at low risk for ischemia, and that it appears safe to discontinue the agent at approximately 15 months after the procedure. Large cohort-based prospective studies or randomized clinical trials are warranted to confirm these results.

Does the COVID-19 Screening Test Affect the Postoperative Prognosis of Patients Who Undergo Emergency Surgery for Cerebral Hemorrhage?

Objective: The coronavirus disease 2019 (COVID-19) pandemic has affected all medical fields, including neurosurgery. Particularly, performing preoperative screening tests has become mandatory, potentially extending the time from admission to the emergency room and operating room, thus possibly affecting patients' prognosis. This study aimed to determine the influence of COVID-19 screening time on patients' postoperative prognosis. Methods: From September 10, 2020, to May 31, 2021, we retrospectively evaluated 54 patients with cerebral hemorrhage who underwent emergency surgery in the emergency room after the screening test. The control group included 89 patients with cerebral hemorrhage who underwent emergency surgery between January 2019 and March 2020, i.e., the period before the COVID-19 pandemic. Prognosis was measured using the Glasgow Coma Scale scores, which were obtained preoperatively, postoperatively, and at discharge, and the modified Rankin Scale (mRS). Additionally, unfavorable outcomes (mRS score 3-6) and in-hospital mortality rates were investigated for postoperative prognostic assessments. Results: No remarkable differences were observed in the time to surgical intervention and prognostic evaluation scores between patients with cerebral hemorrhage who underwent COVID-19 screening tests and subjects in the control group. Conclusion: This study confirmed that patient treatment and prognosis were not significantly affected by additional preoperative screening testing times during the pandemic. We believe that our results are informative for the evaluation and performance of emergency neurosurgery during the pandemic.

Optimal Duration of Dual Antiplatelet Therapy after Stent- Assisted Coil Embolization of Unruptured Intracranial Aneurysms : A Prospective Randomized Multicenter Trial.

OBJECTIVE: Stent-assisted coil embolization (SAC) has been increasingly used to treat various types of intracranial aneurysms. Delayed thromboembolic complications are major concerns regarding this procedure, so dual antiplatelet therapy with aspirin and clopidogrel is needed. However, clinicians vary the duration of dual antiplatelet therapy after SAC, and no randomized study has been performed. This study aims to compare the safety and efficacy of long-term (12 months) dual antiplatelet therapy and shortterm dual antiplatelet therapy (6 months) after SAC for patients with unruptured intracranial aneurysms (UIAs). METHODS: This is a prospective, randomized and multicenter trial to investigate the optimal duration of dual antiplatelet therapy after SAC in patients with UIAs. Subjects will receive dual antiplatelet therapy for 6 months (short-term group) or 12 months (longterm group) after SAC. The primary endpoint is the assessment of thromboembolic complications between 1 and 18 months after SAC. We will enroll 528 subjects (264 subjects in each group) and perform 1 : 1 randomization. This study will involve 14 topperforming, high-volume Korean institutions specializing in coil embolization. RESULTS: The trial will begin enrollment in 2022, and clinical data will be available after enrollment and follow-up. CONCLUSION: This article describes that the aim of this prospective randomized multicenter trial is to compare the effect of short-term (6 months) and long-term (12 months) dual antiplatelet therapy on UIAs in patients undergoing SAC, and to find the optimal duration.

The Spot Sign and Intraventricular Hemorrhage are Associated with Baseline Coagulopathy and Outcome in Intracerebral Hemorrhage.

BACKGROUND: Spontaneous intracerebral hemorrhage (ICH) is the second most prevalent subtype of stroke and has high mortality and morbidity. The utility of radiographic features to predict secondary brain injury related to hematoma expansion (HE) or increased intracranial pressure has been highlighted in patients with ICH, including the computed tomographic angiography (CTA) spot sign and intraventricular hemorrhage (IVH). Understanding the pathophysiology of spot sign and IVH may help identify optimal therapeutic strategies. We examined factors related to the spot sign and IVH, including coagulation status, hematoma size, and location, and evaluated their prognostic value in patients with ICH. METHODS: Prospectively collected data from a single center between 2012 and 2015 were analyzed. Patients who underwent thromboelastography within 24 h of symptom onset and completed follow-up brain imaging and CTA within 48 h after onset were included for analysis. Multivariate logistic regression analyses were performed to identify determinants of the spot sign and IVH and their predictive value for HE, early neurological deterioration (END), in-hospital mortality, and functional outcome at discharge. RESULTS: Of 161 patients, 50 (31.1%) had a spot sign and 93 (57.8%) had IVH. In multivariable analysis, the spot sign was associated with greater hematoma volume (odds ratio [OR] 1.02; 95% confidence interval [CI] 1.00-1.03), decreased white blood cell count (OR 0.88; 95% CI 0.79-0.98), and prolonged activated partial thromboplastin time (OR 1.14; 95% CI 1.06-1.23). IVH was associated with greater hematoma volume (OR 1.02; 95% CI 1.01-1.04) and nonlobar location of hematoma (OR 0.23; 95% CI 0.09-0.61). The spot sign was associated with greater risk of all adverse outcomes. IVH was associated with an increased risk of END and reduced HE, without significant impact on mortality or functional outcome. CONCLUSIONS: The spot sign and IVH are associated with specific hematoma characteristics, such as size and location, but are related differently to coagulation status and clinical course. A combined analysis of the spot sign and IVH can improve the understanding of pathophysiology and risk stratification after ICH.

Reducing amount of contrast agent after compression of right brachial artery using a blood pressure cuff in computed tomography cerebrovascular angiography.

OBJECTIVE: To invastgate feasibility of low-dose contrast agent in cerebral computed tomography angiography (CTA) to alleviate side effects. METHOD: Siemens' Somatom Definition AS+CT scanner, Heine's blood pressure monitor G7-M237 (BP cuff) and Ultravist contrast agent (370 mg Iodine/ml) are used. CTA is acquired using following scan parameters including slice thickness of 1mm, image acquisition parameters of 128×0.6 mm, pitch size of 0.8 mm, 175 effective mAs, 120 kVp tube voltage, scan delay time of 3 seconds, and the scan time of 4 seconds. This study is conducted by securing the IV route in the left antecubital vein before injection of contrast agent, wrapping BP cuff around the branchial artery of the opposite right arm after setting the pressure to 200 mmHg. Then, the injection rate of the contrast agent is fixed at 4.5 cc/sec and contrast agent was injected in three different amounts (70, 80, and 100 cc). Bp cuff is released from this moment when HU value reachs 100. RESULT: In this study, the mean HU values measured from common carotid artery are 412.45±5.89 when injecting 80cc contrast agent and using BP cuff and 399.64±5.51 when injecting 100 cc contrast agenet and not using BP cuff, respectively. In middle cerebral artery M1, the mean HU values are 325.23±38.29 when injecting 80cc contrast agent and using BP cuff and 325.00±30.63 when injecting 100cc contrast agent blood and not using pressure cuff, respectively. Difference of mean HU values is not statistically significant (p > 0.05) with and without using BP cuff. CONCLUSION: This study demonstrates that reducing amount of contrast agent is possible when the right brachial artery is compressed using BP cuff. Study results indicate that reducing 20% injection of contrast agent in CT cerebrovascular angiography can still yield comparable imaging results with conventional contrast angent usage, which implies that less side effects are expected with a contrast agent injection. Thus, this study can serve as a reference for potential reducing side effect during CT cerebrovascular angiography.

Flow Diverter Devices for the Treatment of Unruptured Vertebral Artery Dissecting Aneurysm.

OBJECTIVE: Vertebral artery dissecting aneurysm (VADA) is a very rare subtype of intracranial aneurysms; when ruptured, it is associated with significantly high rates of morbidity and mortality. Despite several discussions and debates, the optimal treatment for VADA has not yet been established. In the last 10 years, flow diverter devices (FDD) have emerged as a challenging and new treatment method, and various clinical and radiological results have been reported about their safety and effectiveness. The aim of our study was to evaluate the clinical and radiological results with the use of FDD in the treatment of unruptured VADA. METHODS: We retrospectively evaluated the data of all patients with unruptured VADA treated with FDD between January 2018 and February 2021 at our hybrid operating room. Nine patients with unruptured VADA, deemed hemodynamically unstable, were treated with FDD. Among other parameters, the technical feasibility of the procedure, procedure-related complications, angiographic results, and clinical outcomes were evaluated. RESULTS: Successful FDD deployment was achieved in all cases, and the immediate follow-up angiography showed intra-aneurysmal contrast stasis with parent artery preservation. A temporary episode of facial numbness and palsy was noted in one patient; however, the symptoms had completely disappeared when followed up at the outpatient clinic 2 weeks after the procedure. The 3-6 months follow-up angiography (n=9) demonstrated complete/near-complete obliteration of the aneurysm in seven patients, and partial obliteration and segmental occlusion in one patient each. In the patient who achieved only partial obliteration, there was a sac 13 mm in size, and there was no change in the 1-year follow-up angiography. In the patient with segmental occlusion, the cause could not be determined. The clinical outcome was modified Rankin Scale 0 in all patients. CONCLUSION: Our preliminary study using FDD to treat hemodynamically unstable unruptured VADA showed that FDD is safe and effective. Our study has limitations in that the number of cases is small, and it is not a prospective study. However, we believe that the study contributes to evidence regarding the safety and effectiveness of FDD in the treatment of unruptured VADA.

A case of an unruptured duplicated middle cerebral artery aneurysm-An unusual presentation of the distal internal carotid artery aneurysm.

The duplicated middle cerebral artery (DMCA) is an anatomic variation that arises from the distal internal carotid artery (ICA) and supplies blood to the middle cerebral artery (MCA) territory. Aneurysms of the DMCA have been reported in 36 cases in 2020. We also report a case of a 3.7 mm saccular aneurysm originating from the DMCA. A 52-year-old woman visited our hospital with worsening headache. She had no neurological abnormalities. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) revealed a right distal ICA aneurysm at the anterior choroidal artery. Cerebral angiography was performed to confirm the shape and the size of the aneurysm. Cerebral angiography revealed that the vessel that was originally identified as the anterior choroidal artery by the MRA was actually the duplicated MCA that was originating from the aneurysm neck and was supplying the MCA territory. The patient's aneurysm was clipped using a transsylvian approach and she recovered without any neurological symptoms. DMCAs are rare and often associated with aneurysms and require preoperative evaluation to confirm the vascular status, aneurysm characteristics, and the shape of the parent artery.

Clinical Efficacy and Safety of Silicone Elastomer Sheet during Decompressive Craniectomy: Anti-Adhesive Role in Cranioplasty.

(1) Background: Cranioplasty is a surgery to repair a skull bone defect after decompressive craniectomy (DC). If the process of dissection of the epidural adhesion tissue is not performed properly, it can cause many complications. We reviewed the effect of a silicone elastomer sheet designed to prevent adhesion. (2) Methods: We retrospectively reviewed 81 consecutive patients who underwent DC and subsequent cranioplasty at our institution between January 2015 and December 2019. We then divided the patients into two groups, one not using the silicone elastomer sheet (n = 50) and the other using the silicone elastomer sheet (n = 31), and compared the surgical outcomes. (3) Results: We found that the use of the sheet shortened the operation time by 24% and reduced the estimated blood loss (EBL) by 43% compared to the control group. Moreover, the complication rate of epidural fluid collection (EFC) in the group using the sheet was 16.7%, which was lower than that in the control group (41.7%, p < 0.023). Multivariate logistic regression analysis showed the sheet (OR 0.294, 95% CI 0.093-0.934, p = 0.039) to be significantly related to EFC. (4) Conclusions: The technique using the silicone elastomer sheet allows surgeons to easily dissect the surgical plane during cranioplasty, which shortens the operation time, reduces EBL, and minimizes complications of EFC.

The experience of surgery and endovascular procedure of cerebrovascular disease in the hybrid operating room; Multi-axis robotic C-arm DSA system.

OBJECTIVE: To report on combined surgical and/or endovascular procedures for cerebrovascular disease in a hybrid operating room (OR). METHODS: Between October 2016 and June 2020, 1832 neurosurgical procedures were performed in a hybrid OR. Our institution's hybrid OR consists of a multi-axis robotic C-arm monoplane digital subtraction angiography (DSA) system with an operating table, 3D-rotational DSA, cone-beam computed tomography (dyna CT), and real-time navigation software. Procedures were categorized into six categories according to purpose (1) simple diagnosis and follow-up, (2) simple endovascular procedure, (3) combination of surgery and endovascular procedures, (4) rescue surgery after endovascular procedures, (5) frameless stereotactic procedure, and (6) other surgeries requiring C-arm. RESULTS: Of 1832 neurosurgical procedures in the hybrid OR, 1430 were simple diagnosis and follow-up cases, 330 simple endovascular procedures, 8 combination of surgery and endovascular procedures, 15 rescue after endovascular procedure, 40 frameless stereotactic procedures, and 9 other surgeries. Eight cases of combination of surgery and endovascular procedures, safely performed without wasting time on patient transfer, were performed in seven bypass end endovascular procedures and one case of bow-hunter syndrome in complex cerebrovascular disease. After embolization, craniotomy (or craniectomy) and intracerebral hemorrhage removal were performed in eight patients in-situ. Of the 40 frameless stereotactic procedure, 37 were extraventricular drainage before/after coil embolization in subarachnoid hemorrhage patients. They all mounted conduits in their planned locations. CONCLUSIONS: A hybrid OR for combined endovascular and surgical procedures represents a safe and useful strategy for cerebrovascular disease. In hybrid ORs various neurosurgical procedures can be safely and conveniently performed. Hybrid OR will pioneer a new era in neurosurgical procedures.

Case Series of Ventriculoatrial Shunt placement in Hybrid Room: Reassessment of Ventriculoatrial Shunt.

OBJECTIVE: Ventriculoatrial shunt (VAS) remains an alternate option for treatment of hydrocephalus in patients with ventriculoperitoneal shunt (VPS) failure. Unfamiliar anatomy for a neurosurgeon has resulted in the VAS falling out of favor as a treatment option. However, there are unsatisfactory reports on the long-term result of VPS, and VAS has been recently re-evaluated. We are to report the simple way to do the VAS using a peel-away sheath in a hybrid operation room. METHODS: A jugular vein path was drawn by ultrasound, a small incision was made above the clavicle, and a shunt catheter was tunneled into it. The jugular vein was punctured beside the tunneled catheter with a Seldinger needle under ultrasound guidance. A flexible guide wire was introduced into the vein and 6-Fr peel-away sheath was advanced into the vein along the wire. Under fluoroscopic guidance, the catheter was cut to position approximately mid-level in the atrium. After the guide wire was removed, the distal shunt catheter was passed down. After confirming proper position of the distal catheter under the fluoroscope, the catheter-guiding sheath was pulled out as a peeling-away manner. We performed this surgical procedures in 5 cases. RESULTS: All the procedures of the VAS using a peel-away sheath were performed in a hybrid operation room Of 5 patients, 3 patients had the distal catheter failures in the peritoneal cavity and 2 patients had shunt A distal catheter was successfully indwelling in all the cases without any difficulties. After the surgery, neither shunt infection nor thromboembolic event happened. CONCLUSION: VAS using fluoroscopy and a peel-away sheath is a good alternative option for hydrocephalus patients with shunt failure related to peritoneal cavity complications.

Clinical Safety and Effectiveness of Stent-Assisted Coil Embolization with Neuroform Atlas Stent in Intracranial Aneurysm.

OBJECTIVE: Stent-assisted coil embolization (SAC) is commonly used for treating wide-neck intracranial aneurysms. In this study, we aimed to assess the clinical safety and efficacy of the NeuroForm Atlas Stent during SAC of intracranial aneurysms. METHODS: We retrospectively analyzed data from patients with ruptured and unruptured cerebral aneurysms, who underwent SAC using the NeuroForm Atlas between February 2018 and July 2018. Favorable clinical outcomes and degree of aneurysm occlusion were defined as a modified Rankin scale score of ≤2 and a Raymond-Roy occlusion classification (RROC) class I/II during the immediate postoperative period and at the 6-month follow-up, respectively. RESULTS: Thirty-one consecutive patients with 33 cases, including 11 ruptured and 22 unruptured cases were treated via NeuroForm Atlas SAC. Among the 22 unruptured cases with 24 unruptured aneurysms had favorable clinical outcome. Complete occlusion (RROC I) was achieved in 16 aneurysms (66.7%), while neck remnants (RROC II) were observed in six aneurysms (25%). Among the 11 patients with ruptured aneurysms, two died due to re-bleeding and diabetic ketoacidosis. In ruptured cases, RROC I was observed in eight (72.7%) and RROC II was observed in three cases (27.3%). At the 6-month follow-up, no clinical events were observed in the 22 unruptured cases. In the ruptured nine cases, five patients recovered without neurologic deficits, while four experienced unfavorable outcomes at 6 months. Of the 29 aneurysms examined via angiography at the 6-month follow-up, 19 (65.5%) were RROC I, eight (27.6%) were RROC II and two (6.9%) were RROC III. There were no procedure-related hemorrhagic complications. CONCLUSION: In this study, we found that stent-assisted coil embolization with NeuroForm Atlas stent may be safe and effective in the treatment of wide-neck intracranial aneurysms. NeuroForm Atlas SAC is feasible for the treatment of both ruptured and unruptured wide-neck aneurysms.

Predictors of Hematoma Enlargement in Patients with Spontaneous Intracerebral Hemorrhage Treated with Rapid Administration of Antifibrinolytic Agents and Strict Conservative Management.

OBJECTIVE: Spontaneous intracerebral hemorrhage (ICH) is caused by the rupture of small blood vessels and other health problems. In ICH patients, hematoma enlargement is the most critical risk factor for poor outcomes. Tranexamic acid, an anti-fibrinolytic agent, has been used to reduce hematoma expansion. We analyzed the risk factors for hematoma expansion in ICH patients and compared the predictability of hematoma expansion in ICH patients with the use of tranexamic acid. METHODS: We performed retrospective analysis of ICH patients who underwent follow-up computed tomography scans from October 2008 to October 2018. Of the 329 included patients, 67 who received tranexamic acid and 262 who did not receive tranexamic acid were compared. We also analyzed the risk factors of 45 and 284 patients who did and did not experience hematoma expansion, respectively. RESULTS: Hematoma expansion was observed in 7 (10.4%) of 67 patients in the tranexamic acid group and 38 (14.5%) of the 262 patients who did not receive tranexamic acid. There was no statistically significant difference between patients who did and did not received tranexamic acid (p=0.389). In the multivariate logistic regression analysis of risk factors for hematoma expansion, spot sign and a maximal diameter of 40 mm were identified as risk factors. CONCLUSION: We could not confirm the effect of tranexamic acid on hematoma expansion in ICH patients. Spot sign and the maximal diameter of hematomas were confirmed as risk factors of hematoma expansion. If the maximal diameter is greater than 40 mm, the hematoma should be closely monitored.

Relevance of Antiplatelet Therapy Duration After Stent-Assisted Coil Embolization for Unruptured Intracranial Aneurysms.

BACKGROUND: The optimal duration of dual-antiplatelet therapy (DAPT) for preventing delayed thromboembolic events (DTEs) remains unclear. We aimed to determine whether longer DAPT provides improved protection against delayed DTEs. METHODS: This retrospective cohort study included 507 stent-assisted coil embolization procedures using a single stent for unruptured intracranial aneurysms. We performed coarsened exact matching according to the duration of maintenance DAPT. DTEs were defined as any neurologic symptoms concerning the stented vascular territory and occurring at 1 month or later after the procedure. After stratification according to DAPT duration (short-term, <9 months; long-term, ≥9 months), the log-rank test and Z-analysis were performed to evaluate the efficacy of long-term DAPT for preventing DTEs. RESULTS: Of 507 treated patients (median follow-up, 44 months), 25 (4.9%) experienced DTEs at 1 month after the procedure. Among all DTEs, 9 (1.8%) were infarctions confirmed on magnetic resonance imaging. Permanent neurologic deficit (modified Rankin Scale score ≥2) occurred in 2 (0.4%) patients. On procedure-to-event analysis, long-term DAPT was not superior for preventing DTEs. Most events occurred within 1 month of switching from DAPT to single-antiplatelet therapy, regardless of DAPT duration. The longest time from the procedure to DTE occurrence was 22 months. Age older than 54.5 years was identified as independent risk factor for DTE-stroke. CONCLUSIONS: Compared with short-term DAPT, long-term DAPT delays the occurrence of DTEs but does not lower their incidence. Longer-term DAPT (>9 months) should be considered after stent-assisted coil embolization for unruptured intracranial aneurysms, although its efficacy remains to be clarified.

Risk factor analysis of recanalization and retreatment for patients with endovascular treatment of internal carotid artery bifurcation aneurysms.

PURPOSE: Only a few reports of internal carotid artery (ICA) bifurcation aneurysms using the endovascular technique have been published in the current literature. The purpose of this study was to assess how multiple risk factors including angioarchitectural features of ICA bifurcation characteristics may have influenced aneurysmal rupture, recanalization, and retreatment. METHODS: Fifty-one patients with 52 ICA bifurcation aneurysms treated with endovascular coiling between July 2003 and July 2015 were retrospectively analyzed. The patients' clinical records, endovascular reports, and clinical and angiographic outcomes were reviewed. We also evaluated risk factors for recanalization and retreatment, including the angioarchitectural anatomy. RESULTS: The clinical outcomes were observed to be satisfactory in 49 patients (96.0%) and unfavorable in 2 patients (4.0%). The risk factor for aneurysmal rupture was young age (P = 0.024). Symptomatic complications due to thromboembolism occurred in 1.9% of cases; no patients suffered a fatal complication. Eleven of 52 ICA bifurcation aneurysms (21.2%) were recanalized within an average of 54.3 ± 33.5 months of follow-up. Among the aneurysms, 4 (7.7%) underwent recoiling. Multivariate analysis showed that ruptured aneurysms (P = 0.006) and a lower packing density (P = 0.048) were risk factors for recanalization. A lower packing density was the only risk factor for retreatment (P = 0.019). CONCLUSION: Endovascular treatment of ICA bifurcation aneurysms is considered safe and acceptable. This study showed that the ICA bifurcation aneurysms ruptured more frequently at a younger age. A higher packing density has been shown to reduce major recanalization and retreatment.

Remote Hemorrhage after Burr Hole Drainage of Chronic Subdural Hematoma.

Chronic subdural hematoma (CSDH) and symptomatic subdural hygroma are common diseases that require neurosurgical management. Burr hole trephination is the most popular surgical treatment for CSDH and subdural hygroma because of a low recurrence rate and low morbidity compared with craniotomy with membranectomy, and twist-drill craniotomy. Many reports suggest that placing a catheter in the subdural space for drainage can further reduce the rate of recurrence; however, complications associated with this type of drainage include acute subdural hematoma, cortical injury, and infection. Remote hemorrhage due to overdrainage of cerebrospinal fluid (CSF) is another possible complication of burr hole trephination with catheter drainage that has rarely been reported. Here, we present 2 cases of remote hemorrhages following burr hole trephination with catheter drainage for the treatment of CSDH and symptomatic subdural hygroma. One patient developed intracerebral hemorrhage and subarachnoid hemorrhage in the contralateral hemisphere, while another patient developed remote hemorrhage 3 days after the procedure due to the sudden drainage of a large amount of subdural fluid over a 24-hour period. These findings suggest that catheter drainage should be carefully monitored to avoid overdrainage of CSF after burr hole trephination.

Bypass Surgery for Complex Intracranial Aneurysms: 15 Years of Experience at a Single Institution and Review of Pertinent Literature.

BACKGROUND: Bypass surgery is a treatment option for complex intracranial aneurysms. OBJECTIVE: To determine the utility of bypass surgery for the treatment of complex intracranial aneurysms and to review the literature on this topic. METHODS: Sixty-two patients were included in this retrospective study. Unruptured aneurysms were dominant (80.6%), and the internal carotid artery was the most common location of the aneurysm (56.4%), followed by the middle cerebral artery (21.0%). The mean maximal diameter of the aneurysms was 20.5 ± 11.4 mm. The clinical and angiographic states were evaluated preoperatively, immediately after surgery (within 3 days) and at the last follow-up. The mean angiographic and clinical follow-up duration was 34.2 ± 38.9 and 46.5 ± 42.5 months, respectively. RESULTS: Sixty-one patients (98.3%) underwent extracranial-intracranial bypass, and 1 underwent intracranial-intracranial bypass. At the last follow-up angiography, 58 aneurysms (93.5%) were completely obliterated and 4 were incompletely obliterated, with a graft patency of 90.3%. Surgical mortality was 0 and permanent morbidity was 8.1%. A good clinical outcome (Karnofsky Performance Scale ≥ 70 and modified Rankin Scale score ≤ 2) was achieved in 91.9% of patients (n = 57). CONCLUSION: With a proper selection of bypass type, bypass-associated treatment can be a good alternative for patients with complex intracranial aneurysms when conventional microsurgical clipping or endovascular intervention is not feasible.

Reversible cerebral vasoconstriction syndrome combined with posterior reversible encephalopathy syndrome after heart transplantation.

Reversible cerebral vasoconstriction syndrome (RCVS) combined with posterior reversible encephalopathy syndrome (PRES) is a rare complication in patients treated with immunosuppressants. A 52-year-old male patient presented with seizures after heart transplantation. The patient was suspected of having PRES on brain images. Despite the strict blood pressure control, the patient presented with altered mentality and the brain images showed a newly developed large acute infarction. Digital subtraction angiography (DSA) revealed the classic "sausage on a string" appearance of the cerebral arteries - potential feature of RCVS. To our knowledge, this is the first case report to describe RCVS combined with PRES after heart transplantation.

P2Y12 Reaction Units Threshold for Implementing Modified Antiplatelet Preparation in Coil Embolization of Unruptured Aneurysms: A Prospective Validation Study.

Purpose To identify and apply an optimized P2Y12 reaction units (PRU) threshold for implementing modified antiplatelet preparation to prevent thromboembolic events in patients nonresponsive to clopidogrel (clopidogrel nonresponders) undergoing coil embolization of unruptured aneurysms and to evaluate the clinical validity. Materials and Methods The optimal PRU threshold for prediction of thromboembolic events was determined with the Youden index in post hoc analysis of a previous, prospectively enrolled cohort of 165 patients in whom the antiplatelet regimen was not modified. This optimal PRU threshold was used to define clopidogrel nonresponders in a prospective validation study of 244 patients. Standard preparation (aspirin, clopidogrel) was maintained for 126 patients responsive to clopidogrel (clopidogrel responders, 51.6%), and modified preparation (aspirin, prasugrel) was prescribed prior to embolization for 118 clopidogrel nonresponders (48.4%). Fifty-seven clopidogrel nonresponders from the previous cohort who did not receive the modified preparation were included as a historical control group. Thromboembolic and bleeding events were compared among groups by using logistic regression analysis. Results Post hoc analysis from the previous cohort yielded PRU of at least 220 as the optimal threshold for modified preparation selection. The thromboembolic event rate of the clopidogrel responders (one of 126 [0.8%]) was lower than that of the historical control group that received standard preparation (seven of 57 patients [12.3%]; adjusted risk difference [RD], -10.1%; 95% confidence interval [CI]: -18.5, -1.7; P = .015) and was similar to that of clopidogrel nonresponders who received modified preparation (one of 118 [0.8%]; adjusted RD, -0.5%; 95% CI: -3.1, 2.1; P = .001 for noninferiority; P = .699 for superiority). Bleeding event rates did not differ among groups (four of 126 clopidogrel responders [3.2%] vs four of 57 clopidogrel nonresponders that received standard preparation [7.0%] [adjusted RD, -4.5%; 95% CI: -11.1, 3.4; P = .228] vs five of 118 clopidogrel nonresponders that received modified preparation [4.2%] [adjusted RD, -0.6%; 95% CI: -5.8, 4.2; P = .813]). Conclusion Patients undergoing coil embolization of unruptured aneurysms, regardless of clopidogrel responsiveness, had low thromboembolic risk when using PRU of at least 220 as the threshold for implementing modified antiplatelet preparation with prasugrel. © RSNA, 2016 Online supplemental material is available for this article.

How High Are Radiation-related Risks in Minimally Invasive Transforaminal Lumbar Interbody Fusion Compared With Traditional Open Surgery?: A Meta-analysis and Dose Estimates of Ionizing Radiation.

STUDY DESIGN: Meta-analysis and dose estimation. OBJECTIVE: The aim of this study was to estimate radiation dose during minimally invasive transforaminal lumbar interbody fusion (MiTLIF) compared with open transforaminal lumbar interbody fusion (OTLIF) and evaluate the risk of radiation-related disease. SUMMARY OF BACKGROUND DATA: MiTLIF was introduced to reduce soft tissue injury and shows favorable perioperative outcomes. However, the disadvantage of MiTLIF is that, compared with OTLIF, it involves high radiation exposure because MiTLIF usually depends on a fluoroscopic guide. The additional cancer risk due to medical radiation exposure during the MiTLIF procedure has not yet been assessed. METHODS: We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials in June 2014 for studies directly comparing MiTLIF and OTLIF. Patient demographics, fluoroscopy time, intraoperative bleeding, and hospitalization period were extracted. The effective dose was converted from fluoroscopy time using formulas from prior studies. RESULTS: Eight cohort studies with a total of 619 patients were identified. Mean fluoroscopy time was 39.42 seconds [95% confidence interval (CI), 38.01-40.83] during OTLIF and 94.21 seconds (95% CI, 91.51-96.91) during MiTLIF according to the meta-analysis. The pooled data revealed that patients who underwent MiTLIF were exposed to 2.4-fold more radiation than those who underwent OTLIF. Patients who underwent OTLIF and MiTLIF were exposed to 0.66 mSv (95% CI, 0.64-0.69) and 1.58 mSv (95% CI, 1.54-1.63) during the surgery, respectively. The lifetime risk of cancer was theoretically increased by 36.4×10 and 87.0×10 after OTLIF and MiTLIF, respectively. The risk of detrimental hereditary disorders associated with OTLIF and MiTLIF is 1.32×10 and 3.16×10, respectively. CONCLUSIONS: Patients who underwent MiTLIF were exposed to 2.4-fold more radiation than those who underwent OTLIF. Although the theoretical cancer risk associated with radiation exposure may be tolerable, stochastic effects should not be disregarded.