The Reproducibility of Cerebrovascular Randomized Controlled Trials

BACKGROUND

Numerous randomized controlled trials (RCTs) relevant to the cerebrovascular field have been performed. The fragility index was recently developed to complement the P value and measure the robustness and reproducibility of clinical findings of RCTs.

OBJECTIVE

In this study, we evaluate the fragility index for key surgical and endovascular cerebrovascular RCTs and propose a novel RCT classification system based on the fragility index.

METHODS

Cerebrovascular RCTs reported between 2000 and 2018 were reviewed. Six key areas were specifically targeted in relation to stroke, carotid stenosis, cerebral aneurysms, and subarachnoid hemorrhage. The correlation between fragility index, number of patients lost to follow-up, and fragility quotient were evaluated to propose a classification system for the robustness of the studies.

RESULTS

A total of 20 RCTs that reported significant differences between both study groups in terms of the primary outcome were included. The median fragility index for the trials was 5.5. An additional 30 randomly selected RCTs were added to propose a classification system with high reliability. The difference between the number of patients lost to follow-up and fragility index inversely correlated with the fragility quotient and was used to divide the robustness of the RCTs into 3 classes reflecting the reproducibility of the trial.

CONCLUSIONS

Neurosurgeons and neurointerventionalists should exercise caution with interpreting the results of cerebrovascular RCTs, especially when the sample size and events numbers are small and there is a high number of patients who were lost to follow-up, as quantitatively identified using the proposed classification system.

Implications of the Collar Sign in Incompletely Occluded Aneurysms after Pipeline Embolization Device Implantation: A Follow-Up Study

BACKGROUND AND PURPOSE

The angiographic collar sign has been recently described in patients with incompletely occluded aneurysms after Pipeline Embolization Device implantation. The long-term implications of this sign are unknown. We report angiographic outcomes of patients with the collar sign with follow-up of up to 45 months and the implications of this angiographic finding.

MATERIALS AND METHODS

We performed a retrospective review of a prospectively maintained data base of patients who underwent Pipeline Embolization Device implantation for an intracranial aneurysm at our institution between January 2014 and December 2016. We included patients with a collar sign at the initial follow-up angiogram after Pipeline Embolization Device implantation.

RESULTS

A total of 198 patients with 285 aneurysms were screened for the collar sign on initial and subsequent follow-up angiograms. There were 226 aneurysms (79.3%) with complete occlusion at the first follow-up. Of 59 incompletely occluded aneurysms, 19 (32.2%) aneurysms in 17 patients were found to have a collar sign on the first angiographic follow-up (median, 6 months; range, 4.2-7.2). Ten (52.6%) aneurysms underwent retreatment with a second Pipeline Embolization Device, which resulted in aneurysm occlusion in 1 (10%) patient. There were only 3 (15.8%) aneurysms with complete occlusion at the last follow-up, 2 (10.5%) of which had a single Pipeline Embolization Device implantation and another single (5.3%) aneurysm with a second Pipeline Embolization Device implantation.

CONCLUSIONS

A collar sign on the initial angiogram after Pipeline Embolization Device placement is a predictor of poor aneurysm occlusion. Because the occlusion rates remain equally low regardless of retreatment in patients with a collar sign, radiologic follow-up may be more appropriate than retreatment.

The geology and geophysics of Kuiper Belt object (486958) Arrokoth

The Cold Classical Kuiper Belt, a class of small bodies in undisturbed orbits beyond Neptune, is composed of primitive objects preserving information about Solar System formation. In January 2019, the New Horizons spacecraft flew past one of these objects, the 36-kilometer-long contact binary (486958) Arrokoth (provisional designation 2014 MU₆₉). Images from the flyby show that Arrokoth has no detectable rings, and no satellites (larger than 180 meters in diameter) within a radius of 8000 kilometers. Arrokoth has a lightly cratered, smooth surface with complex geological features, unlike those on previously visited Solar System bodies. The density of impact craters indicates the surface dates from the formation of the Solar System. The two lobes of the contact binary have closely aligned poles and equators, constraining their accretion mechanism.

Color, composition, and thermal environment of Kuiper Belt object (486958) Arrokoth

The outer Solar System object (486958) Arrokoth (provisional designation 2014 MU₆₉) has been largely undisturbed since its formation. We studied its surface composition using data collected by the New Horizons spacecraft. Methanol ice is present along with organic material, which may have formed through irradiation of simple molecules. Water ice was not detected. This composition indicates hydrogenation of carbon monoxide-rich ice and/or energetic processing of methane condensed on water ice grains in the cold, outer edge of the early Solar System. There are only small regional variations in color and spectra across the surface, which suggests that Arrokoth formed from a homogeneous or well-mixed reservoir of solids. Microwave thermal emission from the winter night side is consistent with a mean brightness temperature of 29 ± 5 kelvin.

Effect of Blood Pressure Variability During the Acute Period of Subarachnoid Hemorrhage on Functional Outcomes

BACKGROUND

The association of blood pressure variation with poor outcomes in aneurysmal subarachnoid hemorrhage (aSAH) is unknown.

OBJECTIVE

To evaluate the association of systolic blood pressure (SBP) variation and clinical outcomes in aSAH.

METHODS

We conducted a retrospective chart review of all aSAH patients treated at an academic institution between 2007 and 2016. Patient demographics, aSAH characteristics, and blood pressure observations for the first 24 h of admission in 4-h intervals were obtained. SBP variability metrics assessed were mean, standard deviation, maximum, minimum, peak, trough, coefficient of variation, and successive variation. The primary outcome was a composite of the modified Rankin scale as good (0-2) or poor (3-6) at last follow-up. Comparisons between outcome groups were performed. Logistic regression models for each significant SBP metric controlling for potential confounders were constructed.

RESULTS

The study population was 202 patients. The mean age was 57 yr; 66% were female. The median follow-up time was 18 mo; 57 (29%) patients had a poor outcome. Patients with poor outcomes had higher standard deviation (17.1 vs 14.7 mmHg, P = .01), peak (23.5 vs 20.0 mmHg, P = .02), trough (22.6 vs 19.2 mmHg, P < .01), coefficient of variation (13.9 vs 11.8 mmHg, P < .01), and lower minimum SBP (101.4 vs 108.4, P < .01). The logistic regression showed that every 1-mmHg increase in the minimum SBP increased the odds of good outcomes (odds ratio = 1.03; 95% CI = 1.001-1.064; P = .04). Models including other SBP metrics were not significant.

CONCLUSION

Hypotension was found to be independently associated with poor outcomes in patients with aSAH.

The solar nebula origin of (486958) Arrokoth, a primordial contact binary in the Kuiper Belt

The New Horizons spacecraft's encounter with the cold classical Kuiper Belt object (486958) Arrokoth (provisional designation 2014 MU₆₉) revealed a contact-binary planetesimal. We investigated how Arrokoth formed and found that it is the product of a gentle, low-speed merger in the early Solar System. Its two lenticular lobes suggest low-velocity accumulation of numerous smaller planetesimals within a gravitationally collapsing cloud of solid particles. The geometric alignment of the lobes indicates that they were a co-orbiting binary that experienced angular momentum loss and subsequent merger, possibly because of dynamical friction and collisions within the cloud or later gas drag. Arrokoth's contact-binary shape was preserved by the benign dynamical and collisional environment of the cold classical Kuiper Belt and therefore informs the accretion processes that operated in the early Solar System.

Symptomatic Hemorrhage From Cerebral Cavernous Malformations: Evidence from a Cohort Study

OBJECTIVE

Patients with a cerebral cavernous malformation (CCM) can have intracranial hemorrhages ranging from insignificant and chronic microbleeds to life-threatening hemorrhage. Management decisions and patient counseling are based on a heterogeneous body of evidence. We sought to improve the literature by providing our results based on the standardized definitions and aimed to delineate differences in the symptomatic burden for CCMs, based on their anatomic location and presence of developmental venous anomalies. This evidence will aid in clinical decision making and patient counseling.

METHODS

A retrospective cohort analysis between 1990 and 2018 was performed, including patients with a diagnosis of a CCM. The primary outcome was acute symptomatic hemorrhages.

RESULTS

We identified 438 patients harboring 632 CCMs. Mean age at diagnosis was 50 years (standard deviation ±17 years). Median follow-up was 26 months (interquartile range, 7-72 hours). Multiple lesions were encountered in 64 patients (15%). An initial symptomatic presentation was observed in 64% of the patients. There were 438 supratentorial lesions (69%) and 194 infratentorial lesions (31%). A symptomatic hemorrhage was observed in 25% of the supratentorial lesions and 29% of the infratentorial lesions (P < 0.001). A linear mixed-effects regression model showed a significant difference in developing a symptomatic hemorrhage at diagnosis or follow-up between CCMs with an infratentorial location and those with a supratentorial location (odds ratio, 1.81; 95% confidence interval, 1.17-2.81; P = 0.008).

CONCLUSIONS

Infratentorial cavernous malformations are more likely to present with symptomatic hemorrhages at diagnosis or during follow-up when accounting for size differences between lesions.

A Direct Aspiration First Pass Technique vs Standard Endovascular Therapy for Acute Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

The direct aspiration first pass technique (ADAPT) is a recent endovascular treatment for ischemic stroke due to large vessel occlusion that has been gaining popularity due to the rapidity of the technique and the potential for cost savings in comparison to standard thrombectomy methods such as stent retrievers. However, few studies have directly compared these 2.

OBJECTIVE

To compare ADAPT with stent retrievers for thrombectomy via systematic review and meta-analysis.

METHODS

Ovid Medline, PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, ACP Journal Club, and Database of Abstracts of Review of Effectiveness limited to English through September 2016 were systematically searched. Eligible studies included those in which patient cohorts underwent ADAPT for acute stroke. Recanalization efficiency, clinical outcomes, and complication rates of ADAPT were compared with the current standard of endovascular thrombectomy techniques.

RESULTS

Seventeen studies on ADAPT and 5 randomized controlled trials on endovascular therapy were included. ADAPT achieved higher rates of complete revascularisation (89.4% vs 71.7%, P < .001) but similar clinical outcomes compared to front-line endovascular therapy. Seventy-one point four percent of ADAPT cases were successfully recanalized with aspiration alone, and a trend towards reduced time from groin puncture to recanalization time was noted (44.77 vs 61.46 min, P = .088).

CONCLUSION

The pooled results are comparable with recent randomized studies that demonstrate the benefit of endovascular therapy over intra-arterial medical therapy. Future direct comparative studies and randomized trials are required to confirm the benefit of the ADAPT strategy compared to standard endovascular therapy for acute ischemic stroke.

A Cohort Comparison Analysis of Fixed Pressure Ventriculoperitoneal Shunt Valves With Programmable Valves for Hydrocephalus Following Nontraumatic Subarachnoid Hemorrhage

BACKGROUND

Hydrocephalus after nontraumatic subarachnoid hemorrhage (SAH) is a common sequela that may require the placement of ventriculoperitoneal shunts (VPS). Adjustable-pressure valves (APVs) are being widely used in this situation though more expensive than differential-pressure valves (DPVs).

OBJECTIVE

To compare outcomes between APV and DPV in SAH-induced hydrocephalus.

METHODS

We performed a retrospective chart review of patients with nontraumatic SAH who underwent VPS placement for the treatment of hydrocephalus after SAH, between July 2007 and December 2016. Patients were classified according to the type of valve (APV vs DPV). We evaluated factors that could predict the type of valve used, outcomes in VPS revision/replacement rate, and complications.

RESULTS

A total of 66 patients underwent VPS placement who were equally distributed into the 2 groups of valves. VPS failure with the need for revision/replacement occurred in 13 (19.7%) cases. Ten (30.3%) patients with DPV had a VPS failure, while 3 (9.1%) patients with an APV had a similar failure with the need for revision/replacement (P = .03). VPS placement before discharge during the initial hospitalization (P = .02) was statistically significant associated with the use of a DPV, while the reason of external ventricular drain (EVD) failure (P = .03) was associated with the use of an APV.

CONCLUSION

APVs had a lower rate of surgical revisions compared to DPVs. Early placement of VPS was associated with the use of a DPV. The need for EVD replacement due to EVD infection or malfunction was associated with higher rates of APV use.

Proposal of a follow-up imaging strategy following Pipeline flow diversion treatment of intracranial aneurysms

OBJECTIVE

There is currently no standardized follow-up imaging strategy for intracranial aneurysms treated with the Pipeline embolization device (PED). Here, the authors use follow-up imaging data for aneurysms treated with the PED to propose a standardizable follow-up imaging strategy.

METHODS

A retrospective review of all patients who underwent treatment for ruptured or unruptured intracranial aneurysms with the PED between March 2013 and March 2017 at 2 major academic institutions in the US was performed.

RESULTS

A total of 218 patients underwent treatment for 259 aneurysms with the PED and had undergone at least 1 follow-up imaging session to assess aneurysm occlusion status. There were 235 (90.7%) anterior and 24 posterior (9.3%) circulation aneurysms. On Kaplan-Meier analysis, the cumulative incidences of aneurysm occlusion at 6, 12, 18, and 24 months were 38.2%, 77.8%, 84.2%, and 85.1%, respectively. No differences in the cumulative incidence of aneurysm occlusion according to aneurysm location (p = 0.39) or aneurysm size (p = 0.81) were observed. A trend toward a decreased cumulative incidence of aneurysm occlusion in patients 70 years or older was observed (p = 0.088). No instances of aneurysm rupture after PED treatment or aneurysm recurrence after occlusion were noted. Sixteen (6.2%) aneurysms were re-treated with the PED; 11 of these had imaging follow-up data available, demonstrating occlusion in 3 (27.3%).

CONCLUSIONS

The authors propose a follow-up imaging strategy that incorporates 12-month digital subtraction angiography and 24-month MRA for patients younger than 70 years and single-session digital subtraction angiography at 12 months in patients 70 years or older. For recurrent or persistent aneurysms, re-treatment with the PED or use of an alternative treatment modality may be considered.

Neural Crest Cell Failure as Embryogenesis for Fusiform Aneurysm of the Anterior Communicating Artery: Case Report and Review of the Literature

BACKGROUND

Pure fusiform aneurysms of the anterior communicating artery (AcomA) are rare. We report a unique case of a patient with an AComA fusiform aneurysm in the setting of several unusual cranial neurocristopathies, including a hypoplastic internal carotid artery (ICA), persistent craniopharyngeal canal, transsphenoidal encephalocele, and ectopic, duplicated pituitary gland. We also review the literature on cranial base neurocristopathies and AComA fusiform aneurysms.

CASE DESCRIPTION

This 46-year-old patient had a history of short stature, osteoporosis, obesity, cleft lip, decreased libido, congenital left eye blindness, headaches, and chronic nasal congestion. Magnetic resonance imaging revealed a 25 × 25 × 33 mm heterogenous soft tissue mass with an ectopic pituitary gland extending transsphenoidally and a duplicated pituitary stalk. A hormone panel revealed undetectable insulin-like growth factor 1 and growth hormone, central hypogonadism, and elevated prolactin. Before presentation, computed tomography angiography (CTA) had revealed a congenitally hypoplastic right ICA and 4.7 × 10.7 mm fusiform aneurysm of the AComA. Digital subtraction angiography confirmed stable morphology after 9 years. Nonoperative management of aneurysm and cephalocele was elected, with repeat CTA in 1 year.

CONCLUSIONS

This case provides evidence that inherent arterial wall defects can contribute to fusiform aneurysm formation in the AComA. We propose that small AComA fusiform aneurysms without sclerotic or symptomatic features can be safely observed by describing the longest reported conservative management for this type of aneurysm. A high degree of suspicion for cerebrovascular anomalies should be maintained in patients who present with cranial neurocristopathy.

Initial results from the New Horizons exploration of 2014 MU69, a small Kuiper Belt object

The Kuiper Belt is a distant region of the outer Solar System. On 1 January 2019, the New Horizons spacecraft flew close to (486958) 2014 MU₆₉, a cold classical Kuiper Belt object approximately 30 kilometers in diameter. Such objects have never been substantially heated by the Sun and are therefore well preserved since their formation. We describe initial results from these encounter observations. MU₆₉ is a bilobed contact binary with a flattened shape, discrete geological units, and noticeable albedo heterogeneity. However, there is little surface color or compositional heterogeneity. No evidence for satellites, rings or other dust structures, a gas coma, or solar wind interactions was detected. MU₆₉'s origin appears consistent with pebble cloud collapse followed by a low-velocity merger of its two lobes.

Sigma-1 receptor antagonist PD144418 suppresses food reinforced operant responding in rats

Sigma-1 (σ1) receptors have been investigated for their involvement in learning, rewarding and motivational processes, particularly as it relates to substances of abuse. Few studies have examined the effects of σ1 receptor agonists and antagonists on the rewarding and motivational properties of natural reinforcers, such as food. Studies that have investigated σ1 receptor agonists and antagonists has produced conflicting results. σ1 receptor antagonist PD144418 has been found to produce a dose-dependent attenuation of locomotor activity induced by cocaine, and by itself, does not suppress basal locomotor activity in mice. However, its effects on reward and motivation as it relates to food are unknown. The present study examined the involvement of σ1 receptors in mediating the rewarding and motivational properties of food using an operant task. The results indicated that at the highest dose (10 μmol/kg), PD144418 significantly attenuated the number of active lever responses for chow pellets but did not decrease the number of active lever responses for sucrose pellets under a fixed ratio (FR2) schedule of reinforcement. However, under a progressive ratio (PR) reinforcement schedule, 10 μmol/kg of PD14418 significantly reduced the breakpoint, a measure indicative of effort or motivation, for both chow and sucrose pellets. When ad libitum chow or sucrose pellets were made freely available (i.e. no lever press required) inside the operant chamber, 10 μmol/kg, PD144418 did not have an effect on number of pellets consumed. These findings indicate that PD144418 reduces the motivational effort of a food reinforced behavior.

No differences in effectiveness and safety between pipeline embolization device and stent-assisted coiling for the treatment of communicating segment internal carotid artery aneurysms

BACKGROUND

Aneurysms arising from the communicating segment (C7) of the internal carotid artery (ICA) are one of the most frequent locations of intracranial aneurysms. Stent-assisted coiling (SAC) and flow diversion therapies are both endovascular strategies used for the treatment of ICA aneurysms occurring at the C7 segment.

OBJECTIVE

The aim of this study is to compare both methods' angiographic and functional outcomes, and procedural complications. To our knowledge, this is the first study to compare both modalities for aneurysms at this location.

METHODS

A retrospective review was performed of our prospectively collected database from 2008 until 2017 for patients treated with SAC and from 2013 until 2017 for patients treated with pipeline embolization devices (PEDs).

RESULTS

We identified 35 patients for this cohort with 38 aneurysms; 17 treated with SAC and 21 with PED. Mean age was 59 years, and 30 patients were female (86%). Complete occlusion at last follow-up occurred in 70.6% of patients in the SAC group and in 81% in the PED group (p = 0.45). Posterior communicating artery patency at last follow-up did not differ significantly between the two groups (94.1% vs 85.7%; p = 0.40). Good functional outcome at last follow-up (mRS 0-2) was achieved in 100% and 88.2% of patients, respectively. Additionally, there was no significant difference between the two groups for retreatment rates, procedural hemorrhagic, or thromboembolic complications.

CONCLUSION

SAC and PED are two equally efficacious modalities for endovascular treatment of ICA aneurysms arising at the communicating segment of the ICA.

Percutaneous Transverse Sinus Cannulation for Dural Arteriovenous Fistula Coiling: Operative Video

This is the case of an 84-year old woman, found to have a symptomatic transverse sinus dural arteriovenous fistula. The transverse sinus was isolated from all venous circulation and its arterial feeders stemmed from the occipital artery, precluding both arterial and venous access for effective obliteration of the fistula. Therefore the patient underwent a combined open surgical/endovascular approach, where the sinus was percutaneously cannulated through a single burr hole, allowing access for effective coiling of the fistula. In this video, we present the rationale, feasibility, and technical implications for this procedure.¹.

On Flow Diversion: The Changing Landscape of Intracerebral Aneurysm Management

Uptake of flow-diverting technology is rapidly outpacing the availability of clinical evidence. Most current usage is off-label, and the endovascular community is nearer the beginning than the end of the learning curve, given the number of devices in development. A comprehensive overview of technical specifications alongside key outcome data is essential both for clinical decision-making and to direct further investigations. Most-studied has been the Pipeline Embolization Device, which has undergone a transition to the Pipeline Flex for which outcome data are sparse or heterogeneous. Alternative endoluminal devices do not appear to be outperforming the Pipeline Embolization Device to date, though prospective studies and long-term data mostly are lacking, and between-study comparisons must be treated with caution. Nominal technical specifications may be unrelated to in situ performance, emphasizing the importance of correct radiologic sizing and device placement. Devices designed specifically for bifurcation aneurysms also lack long-term outcome data or have only recently become available for clinical use. There are no major studies directly comparing a flow-diverting device with standard coiling or microsurgical clipping. Data on flow-diverting stents are too limited in terms of long-term outcomes to reliably inform clinical decision-making. The best available evidence supports using a single endoluminal device for most indications. Recommendations on the suitability and choice of a device for bifurcation or ruptured aneurysms or for anatomically complex lesions cannot be made on the basis of current evidence. The appropriateness of flow-diverting treatment must be decided on a case-by-case basis, considering experience and the relative risks against standard approaches or observation.

Surgical and Endovascular Comprehensive Treatment Outcomes of Unruptured Intracranial Aneurysms: Reduction of Treatment Bias

BACKGROUND

Determining the risks of treatment of unruptured intracranial aneurysms is critical in the decision-making process of management. Most studies have reported the results for endovascular or surgical management. Our objective was to better delineate the risk estimates for unruptured intracranial aneurysms treated with surgical or endovascular techniques in a comprehensive fashion, according to the patients' risk profiles.

METHODS

Data were gathered from 553 patients with 658 unruptured intracranial aneurysms treated at a single institution from 2014 to 2017. The decision to treat was determined by a projected morbidity that was lower than the natural history rupture risk. Data on aneurysm size, location, patient age, and outcome at the last clinical visit (modified Rankin scale scores) were collected and analyzed retrospectively.

RESULTS

The mean patient age was 59 years, and the mean lesion size was 7.3 mm. Microsurgical clipping was used in 251 lesions (38.2%), endovascular coiling in 70 (10.6%), stent-assisted coiling in 89 (13.5%), and a pipeline embolization device in 248 (37.7%). Complications from the procedures or during hospital admission occurred 66 lesions (10% of the total). Of these 66 complications, 28 (4.32% of the total) were non-neurological, treated, and resolved without permanent morbidity. Neurologic complications occurred in 38 procedures (5.7% of the total). Of these, 7 (1%) resulted in a permanent poor outcome (modified Rankin scale score, 3-6).

CONCLUSION

Aneurysmal obliteration using endovascular and surgical approaches in a comprehensive fashion has low treatment risks for unruptured aneurysms. The nomograms generated are useful in the discussion with patients and families regarding the risks of total institutional treatment of unruptured aneurysms.

Impact craters on Pluto and Charon indicate a deficit of small Kuiper belt objects

The flyby of Pluto and Charon by the New Horizons spacecraft provided high-resolution images of cratered surfaces embedded in the Kuiper belt, an extensive region of bodies orbiting beyond Neptune. Impact craters on Pluto and Charon were formed by collisions with other Kuiper belt objects (KBOs) with diameters from ~40 kilometers to ~300 meters, smaller than most KBOs observed directly by telescopes. We find a relative paucity of small craters ≲13 kilometers in diameter, which cannot be explained solely by geological resurfacing. This implies a deficit of small KBOs (≲1 to 2 kilometers in diameter). Some surfaces on Pluto and Charon are likely ≳4 billion years old, thus their crater records provide information on the size-frequency distribution of KBOs in the early Solar System.

Evaluation of Radiological Features of the Posterior Communicating Artery and Their Impact on Efficacy of Saccular Aneurysm Treatment with the Pipeline Embolization Device: A Case Series Study

BACKGROUND

Posterior communicating artery segment aneurysms are one of the most frequent intracranial aneurysms. Currently, limited data have described the use of the pipeline embolization device (PED) in these aneurysms.

METHODS

We conducted a multicenter retrospective review of 3 prospectively collected databases of patients treated with the PED from January 2013 to December 2017. The primary objective was to assess the efficacy and safety of the PED in the treatment of saccular posterior communicating artery (PComA) aneurysms. We also assessed the effect of anatomical variations on the angiographic and clinical outcomes, including the presence of fetal PComA, vessel origin relationship to the aneurysm, and patency after PED placement.

RESULTS

We identified 57 patients with 60 saccular aneurysms; Their mean age was 60.5 years, and 49 were female (86.0%). A total of 55 aneurysms (91.7%) were unruptured. The median imaging follow-up duration was 8.5 months. Complete occlusion at the last imaging follow-up study was 84.0%. At the last follow-up examination, 94.5% of patients had a modified Rankin scale score of ≤2. The presence of fetal PComA, origin type, and patency during follow-up did have a significant effect on aneurysm occlusion (P = 0.61, P = 0.40, and P = 0.14, respectively).

CONCLUSIONS

PED use for treatment of PComA aneurysms resulted in acceptable occlusion rates. The present study did not find that fetal PComA, its origin, or its patency during follow-up had an effect on aneurysm occlusion.

Endothelialization following Flow Diversion for Intracranial Aneurysms: A Systematic Review

BACKGROUND

The underlying mechanism of action of flow diverters is believed to be the induction of aneurysm thrombosis and simultaneous endothelial cell growth along the device struts, thereby facilitating aneurysm exclusion from the circulation. Although extensive attention has been paid to the role of altered cerebrovascular hemodynamics using computational fluid dynamics analyses, relatively less emphasis has been placed on the role of the vascular endothelium in promoting aneurysm healing.

PURPOSE

Our aim was to systematically review all available literature investigating the mechanism of action of flow diverters in both human patients and preclinical models.

DATA SOURCES

A systematic search of PubMed, Cochrane Central Register of Controlled Trials MEDLINE, EMBASE, and the Web of Science electronic data bases was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

STUDY SELECTION

We selected articles assessing the role of endothelialization in flow-diverter treatment of cerebral aneurysms, including both preclinical and clinical studies.

DATA ANALYSIS

Ten articles were eligible for inclusion in this review. Two assessed endothelialization in human patients, while the other 8 used preclinical models (either rabbits or pigs).

DATA SYNTHESIS

Methods used to assess endothelialization included optical coherence tomography and scanning electron microscopy.

LIMITATIONS

A limitation was the heterogeneity of studies.

CONCLUSIONS

Current data regarding the temporal relationship to flow-diverter placement has largely been derived from work in preclinical animal models. Whether these cells along the device struts originate from adjacent endothelial cells or are the result of homing of circulating endothelial progenitor cells is equivocal.