Category: Vascular

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Stereotactic Radiosurgery With Versus Without Embolization for Brain ArteriovenousMalformations

Neurosurgery 88(2) 2021: 313–321

Prior comparisons of brain arteriovenous malformations (AVMs) treated using stereotactic radiosurgery (SRS) with or without embolization were inherently flawed, due to differences in the pretreatment nidus volumes.

OBJECTIVE: To compare the outcomes of embolization and SRS, vs SRS alone for AVMs using pre-embolization malformation features.

METHODS: We retrospectively reviewed International Radiosurgery Research Foundation AVM databases from 1987 to 2018. Patients were categorized into the embolization and SRS (E + SRS) or SRS alone (SRS-only) cohorts. The 2 cohorts were matched in a 1:1 ratio using propensity scores. Primary outcome was defined as AVM obliteration. Secondary outcomes were post-SRS hemorrhage, all-cause mortality, radiologic and symptomatic radiation-induced changes (RIC), and cyst formation.

RESULTS: The matched cohorts each comprised 101 patients. Crude AVM obliteration rates were similar between the matched E + SRS vs SRS-only cohorts (48.5% vs 54.5%; odds ratio = 0.788, P = .399). Cumulative probabilities of obliteration at 3, 4, 5, and 6 yr were also similar between the E + SRS (33.0%, 46.4%, 56.2%, and 60.8%, respectively) and SRSonly (32.9%, 46.2%, 56.0%, and 60.6%, respectively) cohorts (subhazard ratio (SHR)=1.005, P = .981). Cumulative probabilities of radiologic RIC at 3, 4, 5, and 6 yr were lower in the E + SRS (25.0%, 25.7%, 26.7%, and 26.7%, respectively) vs SRS-only (45.3%, 46.2%, 47.8%, and 47.8%, respectively) cohort (SHR = 0.478, P = .004). Symptomatic and asymptomatic embolization-related complication rates were 8.3% and 18.6%, respectively. Rates of post- SRS hemorrhage, all-cause mortality, symptomatic RIC, and cyst formation were similar between the matched cohorts.

CONCLUSION: This study refutes the prevalent notion that AVM embolization negatively affects the likelihood of obliteration after SRS.

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Survival, Dependency, and Health-Related Quality of Life in Patients With Ruptured Intracranial Aneurysm

Neurosurgery 88:252–260, 2021

Previous analyses of the International Subarachnoid Aneurysm Trial (ISAT) cohort have reported on clinical outcomes after treatment of a ruptured intracranial aneurysm with either neurosurgical clipping or endovascular coiling.

OBJECTIVE: To evaluate the long-term quality-adjusted life years (QALYs) gained of endovascular coiling compare to neurosurgical clipping in the UK cohort of ISAT.

METHODS: Between September 12, 1994 and May 1, 2002, patients with ruptured intracranial aneurysms who were assumed treatment equipoise were randomly allocated to either neurosurgical clipping or endovascular coiling. We followed-up 1644 patients in 22 UK neurosurgical centers for a minimum of 10 yr. Health-related quality of life (HRQoL) was collected through yearly questionnaires,measured by utilities calculated from the EQ- 5D-3L. We compared HRQoL between the 2 treatment groups over a period of 10 yr. In all, 1-yr, 5-yr, and 10-yr QALYs were estimated by combining utility and survival information.

RESULTS: Higher average utility values were found in the endovascular group throughout the follow-up period, with mean differences between groups statistically significant in most years. The 10-yr QALYs were estimated to be 6.68 (95% CI: 6.45-6.90) in the coiling group and 6.32 (95% CI: 6.10-6.55) in the clipping group, respectively, a significant mean difference of 0.36 (95% CI: 0.04-0.66). A third of this mean QALYs gain was estimated to derive solely from HRQoL differences.

CONCLUSION: HRQoL after treatment of a ruptured intracranial aneurysm was better after endovascular coiling compared to neurosurgical clipping, which contributed significantly to the QALYs gained over a 10-yr period.

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Small intracranial aneurysms in the Barrow Ruptured Aneurysm Trial (BRAT)

Acta Neurochirurgica (2021) 163:123–129

Treatment of small ruptured aneurysms (SRAs) remains controversial, with literature reporting difficulty with endovascular versus microsurgical approaches. This paper analyzes outcomes after endovascular coiling and microsurgical clipping among patients with SRAs prospectively enrolled in the Barrow Ruptured Aneurysm Trial (BRAT).

Method All BRAT patients were included in this study. Patient demographics, aneurysm size, aneurysm characteristics, procedure-related complications, and outcomes at discharge and at 1-year and 6-year follow-up were evaluated. A modified Rankin scale (mRS) score > 2 was considered a poor outcome.

Results Of 73 patients with SRAs, 40 were initially randomly assigned to endovascular coiling and 33 to microsurgical clipping. The rate of treatment crossover was significantly different between coiling and clipping; 25 patients who were assigned to coiling crossed over to clipping, and no clipping patients crossed over to coiling (P < 0.001). Among SRA patients, 15 underwent coiling and 58 underwent clipping; groups did not differ significantly in demographic characteristics or aneurysm type (P ≥ 0.11). Mean aneurysm diameter was significantly greater in the endovascular group (3.0 ± 0.3 vs 2.6 ± 0.6; P = 0.02). The incidence of procedure-related complications was similar for endovascular and microsurgical treatments (odds ratio [95% confidence interval], 1.0 [0.1–10.0], P = 0.98). Both groups had comparable overall outcome (mRS score > 2) at discharge and 1-year and 6-year follow-up (P = 0.48 and 0.73, respectively).

Conclusions Most SRA patients in the BRAT underwent surgical clipping, with a high rate of crossover from endovascular approaches. Endovascular treatment was equivalent to surgical clipping with regard to procedure-related complications and neurologic outcomes.

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Frequency and risk factors for postoperative aneurysm residual after microsurgical clipping

Acta Neurochirurgica (2021) 163:131–138

Aneurysm residuals after clipping are a well-known problem, but the course of aneurysm remnants in follow-up is not well studied. No standards or follow-up guidelines exist for treatment of aneurysm remnants. The aim of this study was to evaluate the risk factors for postoperative aneurysm remnants and their changes during follow-up.

Methods We performed a retrospective analysis of 666 aneurysms treated via clipping in our hospital from 2006 to 2016. Postoperative and follow-up angiographic data were analyzed for aneurysm remnants and regrowth. Clinical parameters and aneurysm-specific characteristics were correlated with radiological results.

Results The frequency of aneurysm residuals was 12% (78/666). Aneurysms located in the middle cerebral artery (p = 0.02) showed a significantly lower risk for incomplete aneurysm occlusion. Larger aneurysms with a diameter of 11–25 mm (p = 0.005) showed a significantly higher risk for incomplete aneurysm occlusion. Five patients underwent re-clipping during the same hospital stay. Remnants were stratified based on morphological characteristics into “dog ears” (n = 60) and “broad based” (n = 13). The majority of the “dog ears” stayed stable, decreased in size, or vanished during follow-up. Broad-based remnants showed a higher risk of regrowth.

Conclusions A middle cerebral artery location seems to lower the risk for the incomplete clip occlusion of an aneurysm. Greater aneurysm size (11–25 mm) is associated with a postoperative aneurysm remnant. The majority of “dog-ear” remnants appear to remain stable during follow-up. In these cases, unnecessarily frequent angiographic checks could be avoided. By contrast, broadbased residuals show a higher risk of regrowth that requires close imaging controls if retreatment cannot be performed immediately.

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Lateral transorbital approach: an alternative microsurgical route for supratentorial cerebral aneurysms

J Neurosurg 134:72–83, 2021

Transorbital approaches for neurosurgery have recently attracted attention and several anatomical studies have aimed to improve these techniques, but significant deficiencies in clinical practice remain, especially for aneurysm surgery. The authors present an alternative microsurgical route and the results of an analysis of patients with intracranial aneurysms who underwent a lateral transorbital approach (LTOA) using lateral orbito-zygoma-sphenotomy (LOZYGS).

METHODS The clinical and surgical results of a series of 54 consecutive patients with 1 or more aneurysms who underwent surgery via LTOA are reported. A lateral orbitotomy was performed after making a 3-cm skin incision parallel to the lateral orbital rim. A second bone flap, which included the zygoma and sphenoid bones that form the lateral orbital wall, was removed. The lesser sphenoid wing, including the anterior clinoid process, was fully drilled, except in cases of middle cerebral artery (MCA) aneurysms. Cisternal dissection was performed using the classic microsurgical technique starting from the proximal Sylvian fissure and carotid cistern. After the aneurysm was clipped following microsurgical principles, the dura mater was closed in a watertight fashion and 2-piece bone reconstruction was achieved.

RESULTS Sixty aneurysms in 54 patients were clipped using the LOZYGS route. Twenty-one aneurysms were located on the MCA, 30 on the anterior communicating artery, 8 on the internal carotid artery, and 1 at the apex of the basilar artery. The unruptured-to-ruptured aneurysm ratio was 17:43. The operative field was moved to the orbit using the LTOA to avoid interference by bone and muscle tissues. Early proximal control was achieved using a short working distance and direct exposure of the base of the cerebrum, without any requirement for retraction. Because different view angles and surgical corridors were used, no segment of the aneurysm or the parent artery remained unexposed. Therefore, the introduction of additional tools was not required.

CONCLUSIONS The LTOA allowed enhanced broad-perspective exposure of the operative field, early proximal control, and satisfactory surgical freedom. This alternative surgical approach safely exposed the target area and the operative field. The LOZYGS route is safe and effective for the LTOA and microsurgical clipping of anterior circulation aneurysms. According to the authors’ surgical experience and clinical experience, the LTOA can be considered an alternative surgical route to supratentorial aneurysm surgery.

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Giant Fusiform and Dolichoectatic Aneurysms of the Basilar Trunk and Vertebrobasilar Junction

Neurosurgery 88:82–95, 2021

Giant fusiform and dolichoectatic aneurysms of the basilar trunk and vertebrobasilar junction (BTVBJ-GFDA) are extremely difficult to treat. OBJECTIVE: To evaluate factors influencing survival and outcome of BTVBJ-GFDA by performing a retrospective multicenter cohort study.

METHODS: A total of 32 patients with BTVBJ-GFDA were included in this study. Clinicopathological characteristics, treatment measures, and outcomes were collected from medical records and imaging studies. Autopsy and histological findings of the aneurysm and adjacent brain tissue were also obtained in 9 cases.

RESULTS: A total of 11 patients did not undergo surgery, of whom 10 died; 3 from progressive brainstem compression, 4 from subarachnoid hemorrhage, 2 from brainstem infarction, and 1 from associated atherosclerotic disease. The remaining 21 patients underwent a surgical treatment, consisting of immediately proximal parent artery occlusion, remotely proximal parent artery occlusion, clip reconstruction, and distal bypass and achieved significantly longer overall survival compared with those who received conservative therapy (adjusted hazard ratio 1.508, 95% CI 1.058-2.148, P = .02). Histological examination of the aneurysms demonstrated staged clots, open lumen, and intrathrombotic channels with endothelial lining. The patients younger than 45 yr of age showed statistically longer survival than those equal and older than 45 yr (P = .03).

CONCLUSION: Surgical intervention achieved greater survival than conservative management in BTVBJ-GFDA. Narrow ideal treatment window of the blood flow within the aneurysm to maintain sufficient but not excess supply should be targeted based on the hemodynamics of both the posterior communicating arteries and perforating vessel collaterals.

KEYWORDS: Basilar trunk, Dolichoectasia, Dolichoectatic aneurysms, Fusiform aneurysms, Megadolichobasilar anomaly, Vertebrobasilar

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Giant intracranial aneurysms: natural history and 1-year case fatality after endovascular or surgical treatment

J Neurosurg 134:49–57, 2021

Clinical evidence on giant intracranial aneurysms (GIAs), intracranial aneurysms with a diameter of at least 25 mm, is limited. The authors aimed to investigate the natural history, case fatality, and treatment outcomes of ruptured and unruptured GIAs.

METHODS In this international observational registry study, patients with a ruptured or unruptured GIA received conservative management (CM), surgical management (SM), or endovascular management (EM). The authors investigated rupture rates and case fatality.

RESULTS The retrospective cohort comprised 219 patients with GIAs (21.9% ruptured GIAs and 78.1% unruptured GIAs) whose index hospitalization occurred between January 2006 and November 2016. The index hospitalization in the prospective cohort (362 patients with GIAs [17.1% ruptured and 82.9% unruptured]) occurred between December 2008 and February 2017. In the retrospective cohort, the risk ratio for death at a mean follow-up of 4.8 years (SD 2.2 years) after CM, compared with EM and SM, was 1.63 (95% CI 1.23–2.16) in ruptured GIAs and 3.96 (95% CI 2.57–6.11) in unruptured GIAs. In the prospective cohort, the 1-year case fatality in ruptured GIAs/unruptured GIAs was 100%/22.0% during CM, 36.0%/3.0% after SM, and 39.0%/12.0% after EM. Corresponding 1-year rupture rates in unruptured GIAs were 25.0% during CM, 1.2% after SM, and 2.5% after EM. In unruptured GIAs, the HR for death within the 1st year in patients with posterior circulation GIAs was 6.7 (95% CI 1.5–30.4, p < 0.01), with patients with a GIA at the supraclinoid internal carotid artery as reference. Different sizes of unruptured GIAs were not associated with 1-year case fatality.

CONCLUSIONS Rupture rates for unruptured GIAs were high, and the natural history and treatment outcomes for ruptured GIAs were poor. Patients undergoing SM or EM showed lower case fatality and rupture rates than those undergoing CM. This difference in outcome may in part be influenced by patients in the CM group having been found poor candidates for SM or EM.

Clinical trial registration no.: NCT02066493 (clinicaltrials.gov)

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Early surgery for superficial supratentorial spontaneous intracerebral hemorrhage: a Finnish Intensive Care Consortium study

Acta Neurochirurgica (2020) 162:3153–3160

The benefits of early surgery in cases of superficial supratentorial spontaneous intracerebral hemorrhage (ICH) are unclear. This study aimed to assess the association between early ICH surgery and outcome, as well as the cost-effectiveness of early ICH surgery.

Methods We conducted a retrospective, register-based multicenter study that included all patients who had been treated for supratentorial spontaneous ICH in four tertiary intensive care units in Finland between 2003 and 2013. To be included, patients needed to have experienced supratentorial ICHs that were 10–100 cm3 and located within 10 mm of the cortex. We used a multivariable analysis, adjusting for the severity of the illness and the probability of surgical treatment, to assess the independent association between early ICH surgery (≤ 1 day), 12-month mortality rates, and the probability of survival without permanent disability. In addition, we assessed the cost-effectiveness of ICH surgery by examining the effective cost per 1-year survivor (ECPS) and per independent survivor (ECPIS).

Results Of 254 patients, 27%were in the early surgery group. Overall 12-monthmortality was 39%, while 29%survived without a permanent disability. According to our multivariable analysis, early ICH surgery was associated with lower 12-month mortality rates (odds ratio [OR] 0.22, 95% confidence intervals [CI] 0.10–0.51), but not with a higher probability of survival without permanent disability (OR 1.23, 95% CI 0.59–2.56). For the early surgical group, the ECPS and ECPIS were €111,409 and €334,227, respectively. For the non-surgical cohort, the ECPS and ECPIS were €76,074 and €141,471, respectively.

Conclusions Early surgery for superficial ICH is associated with a lower 12-month mortality risk but not with a higher probability of survival without a permanent disability. Further, costs were higher and cost-effectiveness was, thus, worse for the early surgical cohort.

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Early postmarket results with PulseRider for treatment of wide-necked intracranial aneurysms: a multicenter experience

J Neurosurg 133:1756–1765, 2020

Traditionally, stent-assisted coiling and balloon remodeling have been the primary endovascular treatments for wide-necked intracranial aneurysms with complex morphologies. PulseRider is an aneurysm neck reconstruction device that provides parent vessel protection for aneurysm coiling. The objective of this study was to report early postmarket results with the PulseRider device.

METHODS This study was a prospective registry of patients treated with PulseRider at 13 American neurointerventional centers following FDA approval of this device. Data collected included clinical presentation, aneurysm characteristics, treatment details, and perioperative events. Follow-up data included degree of aneurysm occlusion and delayed (> 30 days after the procedure) complications.

RESULTS A total of 54 aneurysms were treated, with the same number of PulseRider devices, across 13 centers. Fourteen cases were in off-label locations (7 anterior communicating artery, 6 middle cerebral artery, and 1 A1 segment anterior cerebral artery aneurysms). The average dome/neck ratio was 1.2. Technical success was achieved in 52 cases (96.2%). Major complications included the following: 3 procedure-related posterior cerebral artery strokes, a devicerelated intraoperative aneurysm rupture, and a delayed device thrombosis. Immediately postoperative Raymond-Roy occlusion classification (RROC) class 1 was achieved in 21 cases (40.3%), class 2 in 15 (28.8%), and class 3 in 16 cases (30.7%). Additional devices were used in 3 aneurysms. For those patients with 3- or 6-month angiographic follow-up (28 patients), 18 aneurysms (64.2%) were RROC class 1 and 8 (28.5%) were RROC class 2.

CONCLUSIONS PulseRider is being used in both on- and off-label cases following FDA approval. The clinical and radiographic outcomes are comparable in real-world experience to the outcomes observed in earlier studies. Further experience is needed with the device to determine its role in the neurointerventionalist’s armamentarium, especially with regard to its off-label use.

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Intraoperative CT and cone-beam CT imaging for minimally invasive evacuation of spontaneous intracerebral hemorrhage

Acta Neurochirurgica (2020) 162:3167–3177

Minimally invasive surgery (MIS) for evacuation of spontaneous intracerebral hemorrhage (ICH) has shown promise but there remains a need for intraoperative performance assessment considering the wide range of evacuation effectiveness. In this feasibility study, we analyzed the benefit of intraoperative 3-dimensional imaging during navigated endoscopyassisted ICH evacuation by mechanical clot fragmentation and aspiration.

Methods 18 patients with superficial or deep supratentorial ICH underwent MIS for clot evacuation followed by intraoperative computerized tomography (iCT) or cone-beamCT (CBCT) imaging. Eligibility for MIS required (a) availability of intraoperative iCT or CBCT, (b) spontaneous lobar or deep ICH without vascular pathology, (c) a stable ICH volume (20–90 ml), (d) a reduced level of consciousness (GCS 5–14), and (e) a premorbid mRS ≤ 1. Demographic, clinical, and radiographic patient data were analyzed by two independent observers.

Results Nine female and 9 male patients with a median age of 76 years (42–85) presented with an ICH score of 3 (1–4), GCS of 10 (5–14) and ICH volume of 54 ± 26 ml. Clot fragmentation and aspiration was feasible in all cases and intraoperative imaging determined an overall evacuation rate of 80 ± 19% (residual hematoma volume: 13 ± 17 ml; p < 0.0001 vs. Pre-OP).Based on the intraoperative imaging results, 1/3rd of all patients underwent an immediate re-aspiration attempt. No patient experienced hemorrhagic complications or required conversion to open craniotomy. However, routine postoperative CT imaging revealed early hematoma re-expansion with an adjusted evacuation rate of 59 ± 30% (residual hematoma volume: 26 ± 37 ml; p < 0.001 vs. Pre-OP).

Conclusions Routine utilization of iCTor CBCT imaging in MIS for ICH permits direct surgical performance assessment and the chance for immediate re-aspiration, which may optimize targeting of an ideal residual hematoma volume and reduce secondary revision rates.

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PulseRider for treatment of wide-necked intracranial aneurysms: a multicenter experience

J Neurosurg 133:1756–1765, 2020

Traditionally, stent-assisted coiling and balloon remodeling have been the primary endovascular treatments for wide-necked intracranial aneurysms with complex morphologies. PulseRider is an aneurysm neck reconstruction device that provides parent vessel protection for aneurysm coiling. The objective of this study was to report early postmarket results with the PulseRider device.

METHODS This study was a prospective registry of patients treated with PulseRider at 13 American neurointerventional centers following FDA approval of this device. Data collected included clinical presentation, aneurysm characteristics, treatment details, and perioperative events. Follow-up data included degree of aneurysm occlusion and delayed (> 30 days after the procedure) complications.

RESULTS A total of 54 aneurysms were treated, with the same number of PulseRider devices, across 13 centers. Fourteen cases were in off-label locations (7 anterior communicating artery, 6 middle cerebral artery, and 1 A1 segment anterior cerebral artery aneurysms). The average dome/neck ratio was 1.2. Technical success was achieved in 52 cases (96.2%). Major complications included the following: 3 procedure-related posterior cerebral artery strokes, a devicerelated intraoperative aneurysm rupture, and a delayed device thrombosis. Immediately postoperative Raymond-Roy occlusion classification (RROC) class 1 was achieved in 21 cases (40.3%), class 2 in 15 (28.8%), and class 3 in 16 cases (30.7%). Additional devices were used in 3 aneurysms. For those patients with 3- or 6-month angiographic follow-up (28 patients), 18 aneurysms (64.2%) were RROC class 1 and 8 (28.5%) were RROC class 2.

CONCLUSIONS PulseRider is being used in both on- and off-label cases following FDA approval. The clinical and radiographic outcomes are comparable in real-world experience to the outcomes observed in earlier studies. Further experience is needed with the device to determine its role in the neurointerventionalist’s armamentarium, especially with regard to its off-label use.

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Lateral supra-cerebellar infra-tentorial approach for P2-P3 junction cerebral aneurysms

Acta Neurochirurgica (2020) 162:2767–2772

P2-P3 junction aneurysms are challenging to treat surgically because of their frequent complex morphology and their location deep in close proximity to the midbrain. The sub-temporal route requires significant retraction of the temporal lobe in addition to potential injury to the vein of Labbe.

We describe the technique for treating such aneurysms via a lateral supra-cerebellar infratentorial (LSCIT) approach, which eliminates manipulation of the temporal lobe.

Method Cadaveric dissection provided comprehensive understanding of relevant anatomy. Intraoperative video shows clipping of the aneurysm using a LSCIT approach.

Conclusion LSCIT approach allows safe clipping of P2-P3 aneurysms with minimal brain manipulation.

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Diagnostic reliability of the Berlin classification for complex MCA aneurysms—usability in a series of only giant aneurysms

Acta Neurochirurgica (2020) 162:2753–2758

The main challenge of bypass surgery of complex MCA aneurysms is not the selection of the bypass type but the initial decision-making of how to exclude the affected vessel segment from circulation. To this end, we have previously proposed a classification for complexMCA aneurysms based on the preoperative angiography. The current study aimed to validate this new classification and assess its diagnostic reliability using the giant aneurysm registry as an independent data set.

Methods We reviewed the pretreatment neuroimaging of 51 patients with giant (> 2.5 cm) MCA aneurysms from 18 centers, prospectively entered into the international giant aneurysm registry. We classified the aneurysms according to our previously proposed Berlin classification for complex MCA aneurysms. To test for interrater diagnostic reliability, the data set was reviewed by four independent observers.

Results We were able to classify all 51 aneurysms according to the Berlin classification for complex MCA aneurysms. Eight percent of the aneurysm were classified as type 1a, 14% as type 1b, 14% as type 2a, 24% as type 2b, 33% as type 2c, and 8% as type 3. The interrater reliability was moderate with Fleiss’s Kappa of 0.419.

Conclusion The recently published Berlin classification for complex MCA aneurysms showed diagnostic reliability, independent of the observer when applied to the MCA aneurysms of the international giant aneurysm registry.

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A Simple Flow Classification Parameter Can Discriminate Rupture Status in Intracranial Aneurysms

Neurosurgery 2020 DOI:10.1093/neuros/nyaa189

A simple dimensionless aneurysm number (An), which depends on geometry and flow pulsatility, was previously shown to distinguish the flow mode in intracranial aneurysms (IA): vortex mode with a dynamic vortex formation/evolution if An > 1, and cavity mode with a steady shear layer if An < 1.

OBJECTIVE: To hypothesize that An > 1 can distinguish rupture status because vortex mode is associated with high oscillatory shear index, which, in turn, is statistically associated with rupture.

METHODS: The above hypothesis is tested on a retrospective, consecutively collected database of 204 patient-specific IAs. The first 119 cases are assigned to training and the remainder to testing dataset. An is calculated based on the pulsatility index (PI) approximated either from the literature or solving an optimization problem (denoted as PI). Student’s t-test and logistic regression (LR) are used for hypothesis testing and data fitting, respectively.

RESULTS: An can significantly discriminate ruptured and unruptured status with 95% confidence level (P<.0001). An (using PI) and An (usingPI) significantly predict the ruptured IAs (for training dataset An: AUC = 0.85, An: AUC = 0.90, and for testing dataset An: sensitivity = 94%, specificity = 33%,An: sensitivity = 93.1%, specificity = 52.85%).

CONCLUSION: An > 1 predicts ruptured status. Unlike traditional hemodynamic parameters such as wall shear stress and oscillatory shear index, An has a physical threshold of one (does not depend on statistical analysis) and does not require time-consuming flow simulations. Therefore, An is a simple, practical discriminator of IA rupture status.

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Aspirin associated with decreased rate of intracranial aneurysm growth

J Neurosurg 133:1478–1485, 2020

Aspirin has emerged as a potential agent in the prevention of rupture of intracranial aneurysms (IAs). In this study, the authors’ goal was to test if aspirin is protective against aneurysm growth in patients harboring multiple IAs ≤ 5 mm.

METHODS The authors performed a retrospective review of a prospectively maintained database covering the period July 2009 through January 2019. Patients’ data were included if the following criteria were met: 1) the patient harbored multiple IAs; 2) designated primary aneurysms were treated by surgical/endovascular means; 3) the remaining aneurysms were observed for growth; and 4) a follow-up period of at least 5 years after the initial treatment was available. Demographics, earlier medical history, the rupture status of designated primary aneurysms, aneurysms’ angiographic features, and treatment modalities were gathered.

RESULTS The authors identified 146 patients harboring a total of 375 IAs. At the initial encounter, 146 aneurysms were treated and the remaining 229 aneurysms (2–5 mm) were observed. During the follow-up period, 24 (10.48%) of 229 aneurysms grew. All aneurysms observed to grow later underwent treatment. None of the observed aneurysms ruptured. Multivariate analysis showed that aspirin was significantly associated with a decreased rate of growth (odds ratio [OR] 0.19, 95% confidence interval [CI] 0.05–0.63). Variables associated with an increased rate of growth included hypertension (OR 14.38, 95% CI 3.83–53.94), drug abuse (OR 11.26, 95% CI 1.21–104.65), history of polycystic kidney disease (OR 9.48, 95% CI 1.51–59.35), and subarachnoid hemorrhage at presentation (OR 5.91, 95% CI 1.83–19.09).

CONCLUSIONS In patients with multiple IAs, aspirin significantly decreased the rate of aneurysm growth over time. Additional prospective interventional studies are needed to validate these findings.

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Assessment of drainage techniques for evacuation of chronic subdural hematoma

J Neurosurg 133:1113–1119, 2017

Surgery for chronic subdural hematoma (CSDH) is one of the most common neurosurgical procedures. The benefit of postoperative passive subdural drainage compared with no drains has been established, but other drainage techniques are common, and their effectiveness compared with passive subdural drains remains unknown.

METHODS In Scandinavian population-based cohorts the authors conducted a consecutive, parallel cohort study to compare different drainage techniques. The techniques used were continuous irrigation and drainage (CID cohort, n = 166), passive subdural drainage (PD cohort, n = 330), and active subgaleal drainage (AD cohort, n = 764). The primary end point was recurrence in need of reoperation within 6 months of index surgery. Secondary end points were complications, perioperative mortality, and overall survival. The analyses were based on direct regional comparison (i.e., surgical strategy).

RESULTS Recurrence in need of surgery was observed in 18 patients (10.8%) in the CID cohort, in 66 patients (20.0%) in the PD cohort, and in 85 patients (11.1%) in the AD cohort (p < 0.001). Complications were more common in the CID cohort (14.5%) compared with the PD (7.3%) and AD (8.1%) cohorts (p = 0.019). Perioperative mortality rates were similar between cohorts (p = 0.621). There were some differences in baseline and treatment characteristics possibly interfering with the above-mentioned results. However, after adjusting for differences in baseline and treatment characteristics in a regression model, the drainage techniques were still significantly associated with clinical outcome (p < 0.001 for recurrence, p = 0.017 for complications).

CONCLUSIONS Compared with the AD cohort, more recurrences were observed in the PD cohort and more complications in the CID cohort, also after adjustment for differences at baseline. Although the authors cannot exclude unmeasured confounding factors when comparing centers, AD appears superior to the more common PD.

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Neurosurgical simulator for training aneurysm microsurgery

Acta Neurochirurgica (2020) 162:2313–2321

Due to its complexity and to existing treatment alternatives, exposure to intracranial aneurysm microsurgery at the time of neurosurgical residency is limited. The current state of the art includes training methods like assisting in surgeries, operating under supervision, and video training. These approaches are labor-intensive and difficult to fit into a timetable limited by the new work regulations. Existing virtual reality (VR)–based training modules lack patient-specific exercises and haptic properties and are thus inferior to hands-on training sessions and exposure to real surgical procedures.

Materials and methods We developed a physical simulator able to reproduce the experience of clipping an intracranial aneurysm based on a patient-specific 3D-printed model of the skull, brain, and arteries. The simulator is made of materials that not only imitate tissue properties including arterial wall patency, thickness, and elasticity but also able to recreate a pulsatile blood flow. A sample group of 25 neurosurgeons and residents (n = 16: early residency with less than 4 years of neurosurgical exposure; n = 9: late residency and board-certified neurosurgeons, 4–15 years of neurosurgical exposure) took part to the study. Participants evaluated the simulator and were asked to answer questions about surgical simulation anatomy, realism, haptics, tactility, and general usage, scored on a 5-point Likert scale. In order to evaluate the feasibility of a future validation study on the role of the simulator in neurosurgical postgraduate training, an expert neurosurgeon assessed participants’ clipping performance and a comparison between groups was done.

Results The proposed simulator is reliable and potentially useful for training neurosurgical residents and board-certified neurosurgeons. A large majority of participants (84%) found it a better alternative than conventional neurosurgical training methods.

Conclusion The integration of a new surgical simulator including blood circulation and pulsatility should be considered as part of the future armamentarium of postgraduate education aimed to ensure high training standards for current and future generations of neurosurgeons involved in intracranial aneurysm surgery. Resident training ,Surgical simulation,Surgical education ,Microsurgery , Intracranial aneurysm , Neurosurgery

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Predictors of Complications, Functional Outcome, and Morbidity in a Large Cohort TreatedWith Flow Diversion

Neurosurgery DOI:10.1093/neuros/nyz508

A dramatic improvement in obliteration rates of large, wide-necked aneurysms has been observed after the FDA approved the Pipeline Embolization Device (PED) in 2011.

OBJECTIVE: To assess the predictors of complications, morbidity, and unfavorable outcomes in a large cohort of patients with aneurysms treated with PED.

METHODS: A retrospective chart review of a prospectively maintained database for subjects treated with flow diversion from 2010 to 2019.

RESULTS: A total of 598 aneurysms were treated during a period extending from 2010 to 2019 (84.28% females, mean age 55.5 yr, average aneurysm size 8.49 mm). Morbidity occurred at a rate of 5.8% and mortality at a rate of 2.2%. Ischemic stroke occurred at a rate of 3%, delayed aneurysmal rupture (DAR) at 1.2%, and distal intraparenchymal hemorrhage (DIPH) at 1.5%. On multivariate analysis, the predictor of stroke was aneurysm size>15 mm. Predictors of DAR were previous subarachnoid hemorrhage (SAH), increasing aneurysm size, and posterior circulation aneurysm. Predictors of DIPH were using more than 1 PED and baseline P2Y12 value. Predictors of in-stent stenosis were the increasing year of treatment and balloon angioplasty, whereas increasing age and previous treatment were negatively associated with in-stent stenosis. Predictors of morbidity were posterior circulation aneurysms, increasing aneurysm size, and hypertension, and incidental aneurysm diagnosis was protective for morbidity.

CONCLUSION: Flow diversion is a safe and effective treatment option for aneurysms. A better understanding of predictive factors of complications, morbidity, and functional outcomes is of high importance for a more accurate risk assessment.

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Craniectomy size for subdural haematomas and the impact on brain shift and outcomes

Acta Neurochirurgica (2020) 162:2019–2027

Midline shift in trauma relates to the severity of head injury. Large craniectomies are thought to help resolve brain shift but can be associated with higher rates of morbidity. This study explores the relationship between craniectomy size and subtemporal decompression for acute subdural haematomas with the resolution of brain compression and outcomes. No systematic study correlating these measures has been reported.

Method A retrospective study of all adult cases of acute subdural haematomas that presented to a Major Trauma Centre and underwent a primary decompressive craniectomy between June 2008 and August 2013. Data collection included patient demographics and presentation, imaging findings and outcomes. All imaging metrics were measured by two independent trained assessors. Compression was measured as midline shift, brainstem shift and cisternal effacement.

Results Thirty-six patients with mean age of 36.1 ± 12.5 (range 16–62) were included, with a median follow-up of 23.5 months (range 2.2–109.6). The median craniectomy size was 88.7 cm2 and the median subtemporal decompression was 15.0 mm. There was significant post-operative resolution of shift as measured by midline shift, brainstem shift and cisternal effacement score (all p < .00001). There was no mortality, and the majority of patients made a good recovery with 82.8% having a Modified Rankin Score of 2 or less. There was no association between craniectomy size or subtemporal decompression and any markers of brain shift or outcome (all R2 < 0.05).

Conclusions This study suggests that there is no clear relationship between craniectomy size or extent of subtemporal decompression and resolution of brain shift or outcome. Further studies are needed to assess the relative efficacy of large craniectomies and the role of subtemporal decompression.

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Four-Dimensional Magnetic Resonance Imaging Assessment of Intracranial Aneurysms

Neurosurgery DOI:10.1093/neuros/nyaa021

Treatment of unruptured intracranial aneurysms can reduce the risk of subarachnoid hemorrhage and its associated morbidity and mortality. However, current methods to predict the risk of rupture and optimize treatment strategies for intracranial aneurysms are limited. Assessment of intra-aneurysmal flow using 4-dimensional magnetic resonance imaging (4D MRI) is a novel tool that could be used to guide therapy.

A systematic search of the literature was performed to provide a state-of-the-art review on 4DMRI assessment of unruptured intracranial aneurysms.

A total of 18 studies were available for review. Eccentric flow on 4D MRI is associated with a greater aspect ratio and peak wall shear stress (WSS). WSS, vorticity, and peak velocity are greater in saccular than fusiform aneurysms. Unstable aneurysms are associated with greater WSS, peak wall stress, and flow jet angle and may exhibit wall enhancement. In comparison to computational fluid dynamics (CFD), 4D MRI has a lower spatial resolution and reports lower WSS and velocity magnitudes, but these parameters equalize when spatial resolution is matched.

4D MRI demonstrates the intra-aneurysmal hemodynamic changes associated with flow diversion, including significantly decreased flow velocity. Thus, 4D MRI is a novel, noninvasive imaging tool used for the evaluation of hemodynamics within intracranial aneurysms. Hemodynamic indices derived from 4D MRI appear to correlate well with the simulated (CFD) values and may be used to measure the success of endovascular therapies and risk factors for aneurysm growth and rupture.

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