Introduction Endovascular therapy (EVT) has revolutionized acute stroke treatment, but large vessel recanalization does not always result in tissue‐level reperfusion. Cerebral blood flow (CBF) is not routinely monitored during EVT. Here we aimed to leverage diffuse correlation spectroscopy (DCS), a novel transcranial optical imaging technique, to assess the relationship between microvascular CBF and post‐EVT outcomes. Methods Frontal lobe CBF was monitored by DCS in 40 patients undergoing EVT. Baseline CBF deficit was calculated as the percentage of CBF impairment on pre‐EVT CT perfusion. Microvascular reperfusion was calculated as the percentage increase in DCS‐derived CBF that occurred with recanalization. The adequacy of reperfusion was defined by persistent CBF deficit, calculated as: baseline CBF deficit ‐ microvascular reperfusion. Good functional outcome was defined as 90‐day modified Rankin Scale ≤2. Results 36 (of 40) patients achieved successful recanalization, in whom microvascular reperfusion in itself was not associated with infarct volume or functional outcome. However, patients with good functional outcomes had a smaller persistent CBF deficit (median: 1%; IQR: ‐11%–16%) than patients with poor outcomes (median: 28%; IQR: 2%–50%), p=0.02. Smaller persistent CBF deficit was also associated with smaller infarct volume (p=0.004). Multivariate models confirmed that persistent CBF deficit was independently associated with infarct volume and functional outcome. Conclusion CBF augmentation alone does not predict post‐EVT outcomes, but when microvascular reperfusion closely matches the baseline CBF deficit, patients experience favorable clinical and radiographic outcomes. By recognizing inadequate reperfusion, bedside CBF monitoring may provide opportunities to personalize post‐EVT care aimed at CBF optimization.

BACKGROUND:Historically, the transfemoral approach (TFA) has been the most common access site for cerebral intraoperative angiography (IOA). However, in line with trends in cardiac interventional vascular access preferences, the transradial approach (TRA) and transulnar approach (TUA) have been gaining popularity owing to favorable safety and patient satisfaction outcomes. OBJECTIVE:To compare the efficacy and safety of TRA/TUA and TFA for cerebral and spinal IOA at an institutional level over a 6-year period. METHODS:Between July 2016 and December 2022, 317 angiograms were included in our analysis, comprising 60 TRA, 10 TUA, 243 TFA, and 4 transpopliteal approach cases. Fluoroscopy time, contrast dose, reference air kerma, and dose-area products per target vessel catheterized were primary endpoints. Multivariate regression analyses were conducted to evaluate predictors of elevated contrast dose and radiation exposure and to assess time trends in access site selection. RESULTS:Contrast dose and radiation exposure metrics per vessel catheterized were not significantly different between access site groups when controlling for patient position, operative region, 3D rotational angiography use, and different operators. Access site was not a significant independent predictor of elevated radiation exposure or contrast dose. There was a significant relationship between case number and operative indication over the study period (P<0.001), with a decrease in the proportion of cases for aneurysm treatment offset by increases in total cases for the management of arteriovenous malformation, AVF, and moyamoya disease. CONCLUSIONS:TRA and TUA are safe and effective access site options for neurointerventional procedures that are increasingly used for IOA.

BACKGROUND:Endovascular therapy for acute ischemic stroke has revolutionized clinical care for patients with stroke and large vessel occlusion, but treatment remains time sensitive. At our stroke center, up to half of the door-to-groin time is accounted for after the patient arrives in the angio-suite. Here, we apply the concept of a highly visible timer in the angio-suite to quantify the impact on endovascular treatment time. METHODS:This was a single-center prospective pseudorandomized study conducted over a 32-week period. Pseudorandomization was achieved by turning the timer on and off in 2-week intervals. The primary outcome was angio-suite-to-groin time, and secondary outcomes were angio-suite-to-intubation time, groin-to-recanalization time, and 90-day modified Rankin scale. A stratified analysis was performed based on type of anesthesia (ie, endotracheal intubation versus not). RESULTS:During the 32-week study period, 97 mechanical thrombectomies were performed. The timer was on and off for 38 and 59 cases, respectively. The timer resulted in faster angio-suite-to-groin time (28 versus 33 minutes; P=0.02). The 5-minute reduction in angio-suite-to-groin was maintained after adjusting for intubation status in a multivariate regression (P=0.02). There was no difference in the 90-day modified Rankin scale between groups. The timer impact was consistent across the 32-week study period. CONCLUSIONS:A highly visible timer in the angio-suite achieved a meaningful, albeit modest, reduction in endovascular treatment time for patients with stroke. Given the lack of risk and low cost, it is reasonable for stroke centers to consider a highly visible timer in the angio-suite to improve treatment times.

The artery of Davidoff and Schechter (ADS) is the only meningeal branch of the posterior cerebral artery (PCA), supplying the medial tentorial margin and posterior portions of the falx. Given its small size, it is rarely identified on angiographic studies, unless enlarged in pathologies such as dural arteriovenous fistulas (DAVFs) or vascularized masses. This artery was first described by Wollschlaeger and Wollschlaeger in 1965, and to date, only a few reports have described its significance. The objective of this study is to report our experience with the ADS in dural fistulas from 2 tertiary medical centers and to emphasize the importance of recognizing this artery during angiographic examination of vascular tentorial and posterior fossa lesions. To our knowledge, this report demonstrates the largest angiographic case series published to date, recognizing a total of 7 patients with ADS arising secondary to a posterior fossa or tentorial DAVF and one of the largest reported series of DAVFs supplied by the ADS treated by endovascular and surgical techniques. Our cases validate the importance of prompt identification of the ADS for the diagnosis as well as endovascular treatment of vascular malformations in the posterior fossa and tentorial region.

Objective Puig types 2 through 4 venous malformations (VMs) are challenging to treat with sclerotherapy given their robust systemic outflow. Endovenous balloon occlusion offers a means of temporarily occluding systemic venous outflow to allow for more complete sclerotherapy. This study reviews our experience of implementing this technique in patients with Puig advanced (types 2 through 4) VMs. Methods An IRB approved review of treated venous malformations from 2013–2016 revealed 10 patients fitting inclusion criteria. Patient demographics, pre-procedural imaging, intra-procedural technical parameters, and post-procedural follow-up outcomes were recorded. All patients underwent temporary balloon occlusion of a systemic or major draining vein during sclerotherapy. Embolic agents included n-butyl cyanoacrylate glue, sodium tetradecyl sulfate foam, and coils. Standard 5 French angioplasty balloons ranged from 4 to 8 mm diameter and 2 to 8 cm length depending on vessel requiring occlusion. All patients underwent minimum 3-year follow-up questionnaire administration re-assessing resolution of lesion symptomology and post-procedural quality of life (QoL) measures. Results Of the 10 VMs treated, 2 were Type 2, 6 were Type 3, and 2 were Type 4. More than one sclerotherapy session was required in 7/10 patients (mean: 2, range: 1–4). Most common sites of VM systemic drainage included subclavian, popliteal, internal/external jugular, and basilic veins. All patients had no indication for further sclerotherapy following adjunctive balloon occlusion. No non-target embolization or immediate post-procedural complications occurred. Follow-up questionnaires (mean interval: 3 years 6 months, range: 3 years–3 years 11 months) confirmed the persistence of embolization effects, improved QoL, and no additional sclerotherapy sessions for all patients in the cohort. Conclusions Endovenous balloon occlusion as an adjunct to sclerotherapy can be considered when treating patients with types 2–4 venous malformations. This technique lowers the risk of non-target systemic venous embolization, allowing for operator-driven deeper intralesional sclerosant penetration and subsequently maintained treatment efficacy.

Temporomandibular joint (TMJ) arthroscopy is considered a safe, minimally invasive procedure for the treatment of certain TMJ derangements. However, as TMJ arthroscopy is being popularized, more complications are being reported. Though exceedingly rare, arteriovenous fistula (AVF) can occur. We describe a case of superficial temporal artery (STA) fistula formation successfully treated with coil embolization.

Since the initial reports surfaced of a novel coronavirus causing illness and loss of life in Wuhan, China, COVID-19 has rapidly spread across the globe, infecting millions and leaving hundreds and thousands dead. As hospitals cope with the influx of patients with COVID-19, new challenges have arisen as health-care systems care for patients with COVID-19 while still providing essential emergency care for patients with acute strokes and acute myocardial infarction. Adding to this complex scenario are new reports that patients with COVID-19 are at increased risk of thromboembolic complications including strokes. In this article, we detail our experience caring for acute stroke patients and provide some insight into neurointerventional workflow modifications that have helped us adapt to the COVID-19 era.

Aims The purpose of our study was to analyze utilization trends and physician specialty distribution in spinal catheter angiography and magnetic resonance angiography in the Medicare fee-for-service population. Methods Data from the CMS Physician/Supplier Procedure Summary Master Files for 2004 to 2016 were used for this study. The Current Procedural Terminology version 4 codes for spinal magnetic resonance angiography (72159) and spinal catheter angiography (75705) were used to analyze the volumes of these procedures. Using Medicare’s 108 specialty code, we compared procedure volumes among physician specialties. Data analysis was performed using SAS version 9.3 for Windows. Results The volume of spinal catheter angiography performed was 4758 in 2004, peaked at 6869 in 2012, and dropped to 6656 in 2016. Overall, the volume of spinal catheter angiography increased by 40% from 2004 to 2016. Radiologists performed the majority of these procedures (3736 or 56.1%) in 2016, followed by neurosurgeons (2456 or 36.9%), and neurologists (346 or 5.2%). The spinal magnetic resonance angiography volume fluctuated between 0 and 1 from 2004 to 2009, then precipitously increased to 40 in 2010, peaked at 133 in 2011, and declined to 81 in 2016. The volume of spinal magnetic resonance angiography procedures increased by 8000% from 2004 to 2016, with radiologists performing the majority of them. Conclusion Our results show that spinal catheter angiography volumes continue to rise in the Medicare fee-for-service population, and are largely performed by radiologists, neurosurgeons, and neurologists. Although spinal magnetic resonance angiography volumes have started to increase, they comprise only a small fraction of studies performed for vascular evaluation of the spine.

BACKGROUND:Because treatments for cerebral arterial spasm-a delayed consequence of subarachnoid hemorrhage (SAH)-are clinically inconsistent, we describe here a new method for reversal of arterial spasm, possibly extensible to nitric oxide (NO)-sensitive microvasculature. METHODS:We subjected dogs to the intracisternal double-hemorrhage model of SAH (autologous blood injection on days 1 and 3) and began endovascular treatment of the spasmed basilar artery (BA) on Day 4. A conical-tip fused silica optical fiber was introduced via a microcatheter (inserted femorally) into the proximal vicinity of the spasmed BA. After local saline flushing of blood, an ultraviolet (UV) pulsed laser beam (355 nm Nd:YAG) was focused into the optical fiber and converted into a concentric ring beam, which facilitated endovascular irradiation for 30 s at intensities of 12-20 W/cm2. BA diameters were measured angiographically using a semiautomated routine over the entire BA length as well as the proximal, medial, and distal segments. RESULTS:On Day 4 the BAs had constricted by 21 ± 11%. After UV laser irradiation on Day 4, the constricted BAs dilated to 93 ± 15% of their normal diameters within minutes, and the dilation (91 ± 12%) persisted on Day 5. Most BA segments recovered to their respective baselines after UV irradiation, even when the UV beam was located considerably proximal to the BA origin. At days 4 and 5, the percent BA dilation normalized to Day 4 pre-treatment decreased linearly (by scatter plot, p < 0.02) over a range of about 60 mm from the UV irradiation site. CONCLUSIONS:We conjecture that the vasodilator nitric oxide, produced at high local concentration from its vascular storage forms (chiefly nitrites) by UV laser-induced photoscission, stimulates a wave of arterial dilation, possibly by longitudinal propagation of transnitrosation reactions in the arterial wall, which reverses cerebral vasospasm semi-locally and thus avoids the deleterious effects of systemic treatment.

Background: Endovascular thrombectomy (EVT) is effective in patients with large vessel occlusion (LVO) stroke. We hypothesized that a tortuous internal carotid (ICA) may increase the technical difficulty of EVT and prevent optimal positioning of aspiration catheters thereby lowering the chances of successful recanalization and likelihood of favorable outcome. Patients and Methods: Consecutive patients with LVO and patent cervical ICAs who underwent EVT at 2 academic centers were included. Demographics, clinical and radiological factors, time metrics, occurrence of symptomatic intracranial hemorrhage (sICH), functional outcome and survival data were collected. ICA tortuosity was determined on pre-EVT sagittal maximal intensity projection images and classified into three categories: type 1 - straight ICA trunk, type 2 - moderate degree of tortuosity not judged to impair distal catheter placement and type 3 - severe tortuosity preventing optimal aspiration catheter placement. Thrombolysis in cerebral infarction (TICI) 2b-3 was considered successful recanalization and modified Rankin Scale (mRS)≤2 90days post stroke was considered favorable outcome. Results: The study included 313 patients (mean age 69±15, median NIHSS 17), and 53% had type 1, 33% type 2 and 14% type 3 ICA tortuosity. Severe tortuosity was significantly less common in patients with atrial fibrillation (p=0.032) but no other factors were associated with the degree of tortuosity. Overall, 85% had successful recanalization and 47% had favorable outcomes. The chances of favorable outcome at 90days were independent of the degree of observed tortuosity (53% type1, 32% type2 and 49% type3 respectively, p=0.94). Similarly, mortality rates, chances of succesful recanalization and sICH rates did not differ between the tortuosity groups. Clustering patients with moderate and severe tortuosity into one group showed that those with marked tortuosity were significantly older (74±12 vs. 65±16; p<0.0001) and less frequently achieved successful recanalization (79% vs. 89%; p=0.018) but had similar functional outcomes and survival rates compared to those with mild tortuosity. Conclusions: Carotid tortuosity does not impact functional outcome but may influence recanalization rates.

Background and Purpose: Stent-assisted coil embolization using the new generation Neuroform Atlas Stent System has shown promising safety and efficacy. The primary study results of the anterior circulation aneurysm cohort of the treatment of wide-neck, saccular, intracranial, aneurysms with the Neuroform Atlas Stent System (ATLAS trial [Safety and Effectiveness of the Treatment of Wide Neck, Saccular Intracranial Aneurysms With the Neuroform Atlas Stent System]) are presented. Methods: ATLAS IDE trial (Investigational Device Exemption) is a prospective, multicenter, single-arm, open-label study of wide-neck (neck ≥4 mm or dome-to-neck ratio <2) intracranial aneurysms in the anterior circulation treated with the Neuroform Atlas Stent and approved coils. The primary efficacy end point was complete aneurysm occlusion (Raymond-Roy class 1) on 12-month angiography, in the absence of retreatment or parent artery stenosis (>50%) at the target location. The primary safety end point was any major stroke or ipsilateral stroke or neurological death within 12 months. Adjudication of the primary end points was performed by an independent Imaging Core Laboratory and the Clinical Events Committee. Results: A total of 182 patients with wide-neck anterior circulation aneurysms at 25 US centers were enrolled. The mean age was 60.3±11.4 years, 73.1% (133/182) women, and 80.8% (147/182) white. Mean aneurysm size was 6.1±2.2 mm, mean neck width was 4.1±1.2 mm, and mean dome-to-neck ratio was 1.2±0.3. The most frequent aneurysm locations were the anterior communicating artery (64/182, 35.2%), internal carotid artery ophthalmic artery segment (29/182, 15.9%), and middle cerebral artery bifurcation (27/182, 14.8%). Stents were placed in the anticipated anatomic location in all patients. The study met both primary safety and efficacy end points. The composite primary efficacy end point of complete aneurysm occlusion (Raymond-Roy 1) without parent artery stenosis or aneurysm retreatment was achieved in 84.7% (95% CI, 78.6%–90.9%) of patients. Overall, 4.4% (8/182, 95% CI, 1.9%–8.5%) of patients experienced a primary safety end point of major ipsilateral stroke or neurological death. Conclusions: In the ATLAS IDE anterior circulation aneurysm cohort premarket approval study, the Neuroform Atlas stent with adjunctive coiling met the primary end points and demonstrated high rates of long-term complete aneurysm occlusion at 12 months, with 100% technical success and <5% morbidity. Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT02340585.

BACKGROUND:The artery of Wollschlaeger and Wollschlaeger is a tentorial branch of the superior cerebellar artery that is usually not visualized on conventional cerebral angiography, unless it is pathologically enlarged. It can be recruited as part of the blood supply to tentorial dural arteriovenous fistulas (AVFs), although this occurs infrequently.CASE DESCRIPTION:Here we report the clinico-radiologic evaluation and treatment of a 48-year-old man referred to our institution for hitherto workup negative progressive, relapsing quadriparesis. This represents the first reported case of cervical myelopathy caused by venous congestion from a type V dural AVF supplied by the artery of Wollschlaeger and Wollschlaeger.CONCLUSIONS:The anatomic discrepancy between the symptomatic spinal cord lesion and the etiologic intracranial fistula frequently results in delayed care in cases of myelopathy due to intracranial dural AVFs. Familiarity with these disorders and of their pathophysiologic mechanisms is important to avoid unnecessary diagnostic delays.

Purpose There is now class 1a evidence for the efficacy of mechanical thrombectomy in patients with acute ischemic stroke and a large vessel occlusion (LVO).1 2 Failure to recanalize portends a poor prognosis for the patient with a decreased chance for a good function outcome (modified Rankin Score of 2 or less). The purpose of our study was to evaluate the incidence and causes of persistent occlusion of intracranial large vessel occlusion following mechanical thrombectomy at our high-volume comprehensive stroke center, with the goal of providing some insight into potential ways to increase recanalization rates in future patients. Methods After institutional board approval, a prospectively maintained institutional thrombectomy database for acute ischemic stroke was queried from 2015 to present. Patients with documented large vessel occlusion in the intracranial circulation and failure to recanalize after attempted mechanical thrombectomy were included for analysis. Patient characteristics including age, sex, co-morbidities, baseline NIHSS score, and baseline ASPECTS, were recorded. Rates of symptomatic hemorrhage, final ASPECTS, need for decompressive hemicraniectomy, and outcomes at 90 days (modified Rankin Scale) were also included. The statistical package R was used for analysis. Results 24 out of 368 patients with LVO and acute ischemic stroke had persistent TICI 0 occlusions after attempted mechanical thrombectomy. 15 patients were male. Mean age of patients with persistent TICI 0 was 68.8 years (range 44 to 94 years). A combination of stent-retrievers and direct aspiration (solumbra) was used for mechanical thrombectomy in all cases were the lesion was accessible. The most common reason for persistent TICI 0 was failure to recanalize despite adequate stent apposition and aspiration, which occurred in 18 out of 24 cases, or 75% of cases. Inability to pass a microwire through the site of occlusion was the second most common reason for persistent TICI 0, which occurred in 5 out of 24 of cases (21%). Inability to select the proximal great vessels due to extreme tortuosity only occurred in one case. 11 out of the 24 patients with persistent TICI 0 occlusions died within 90 days of attempted thrombectomy. Conclusions The rate of TICI 0 mechanical thrombectomy was extremely low in our series, accounting for only 7% of thrombectomy cases at our high-volume stroke center. Failure to recanalize the site of large vessel occlusion was the most common reason for persistent TICI 0 after attempted mechanical thrombectomy in our large series, occurring in 75% of persistent TICI 0 cases. In our series, persistent TICI 0 after mechanical thrombectomy had a high mortality rate, nearly 50%. References Berkhemer OA, Fransen PS, Beumer D, van den Berg LA, Lingsma HF, Yoo AJ, et al. A randomized trial of intraarterial treatment for acute ischemic stroke. N Engl J Med 2015;372(1):11–20. Goyal M, Demchuk AM, Menon BK, Eesa M, Rempel JL, Thornton J, et al. Randomized assessment of rapid endovascular treatment of ischemic stroke. N Engl J Med 2015;372(11):1019–30. Disclosures R. Mattay: None. M. Cox: None. M. McCabe: None. J. Schmitt: None. D. Kung: None. O. Choudhri: None. B. Pukenas: 2; C; Regenxbio, Prevail Therapeutics. R. Hurst: None.

Purpose Loss of the T2 vertebral artery flow void can be an ominous sign in patients with trauma. However, the significance of an absent vertebral artery flow void is less clear when discovered incidentally in patients without trauma or acute neurological symptoms. The purpose of this study was to review retrospectively the results of additional imaging and clinical evaluation in atraumatic patients without acute neurological symptoms found to have an incidentally discovered absent vertebral artery flow void on magnetic resonance imaging. Materials and methods An imaging database was reviewed for absent vertebral artery flow voids in atraumatic cervical spine magnetic resonance images. Imaging and long-term clinical follow-up were recorded. Results Fifty-four patients were included in the study. All patients had clinical follow-up and 22 patients (40% of cases) had vascular imaging follow-up. Nine patients had a hypoplastic but patent vertebral artery on follow-up vascular imaging, and no further action was taken. Ten patients had evidence of stenosis or occlusion of the vertebral artery on follow-up imaging, none with acute neurological symptoms or new symptoms/subsequent change in management during follow-up. Three additional patients had vertebral artery dissections on follow-up imaging, but all of them had acute neurological symptoms at the time of imaging and acute infarcts on current or subsequent magnetic resonance imaging. The other 32 patients had clinical follow-up and remained asymptomatic throughout the study period, without change in management. Conclusion In the absence of trauma or acute neurological symptoms an absent vertebral artery flow void has a low likelihood of altering patient management.

INTRODUCTION:Mechanical thrombectomy is revolutionizing treatment of acute stroke due to large vessel occlusion (LVO). Unfortunately, use of the modified Thrombolysis in Cerebral Infarction score (mTICI) to characterize recanalization of the cerebral vasculature does not address microvascular perfusion of the distal parenchyma, nor provide more than a vascular "snapshot." Thus, little is known about tissue-level hemodynamic consequences of LVO recanalization. Diffuse correlation spectroscopy (DCS) and diffuse optical spectroscopy (DOS) are promising methods for continuous, noninvasive, contrast-free transcranial monitoring of cerebral microvasculature. METHODS:Here, we use a combined DCS/DOS system to monitor frontal lobe hemodynamic changes during endovascular treatment of 2 patients with ischemic stroke due to internal carotid artery (ICA) occlusions. RESULTS AND DISCUSSION:The monitoring instrument identified a recanalization-induced increase in ipsilateral cerebral blood flow (CBF) with little or no concurrent change in contralateral CBF and extracerebral blood flow. The results suggest that diffuse optical monitoring is sensitive to intracerebral hemodynamics in patients with ICA occlusion and can measure microvascular responses to mechanical thrombectomy.

BACKGROUND:Subclavian steal phenomenon can cause retrograde flow in the vertebral artery as a result of ipsilateral occlusion of the subclavian artery. This phenomenon has various clinical presentations, such as claudication of the affected extremity or intermittent vertebrobasilar ischemia. Aneurysm formation in the spinal cord circulation is exceptionally rare but may occur secondary to collateral formation in subclavian steal syndrome.CASE DESCRIPTION:The case presented herein is a 53-year-old male who presented with headache and severe neck pain. Imaging studies revealed that the patient had subarachnoid hemorrhage in the perimedullary and cervicomedullary cisterns and extending to C3-C7 ventrally. Computed tomography angiography reconstruction demonstrated an aneurysmally dilated vessel dorsal to the C6 vertebral body within the spinal canal. Catheter-based angiography of the right subclavian artery demonstrated retrograde flow within the left vertebral artery and confirmed proximal left subclavian artery occlusion, findings diagnostic of subclavian steal. Further, a branch of the right thyrocervical trunk supplied a retrocorporeal artery collateral to the left vertebral artery, which also contributed to the anterior spinal artery.CONCLUSIONS:After endovascular coiling of the aneurysm, the patient had no neurologic deficits or postoperative complications. Postoperative angiography revealed complete obliteration with no residual aneurysm. Imaging further demonstrated patency of the radiculomedullary (anterior spinal) artery.

OBJECTIVEThe purposes of this study were to document recent trends in stroke intervention at a tertiary-care facility with a comprehensive stroke center and to analyze current procedure volumes and the employment of specialty providers in neurointerventional radiology (NIR).MATERIALS AND METHODSInstitutional trends in the volume of mechanical thrombectomy were analyzed on the basis of the number of patients who underwent mechanical thrombectomy from 2013 to 2017. To evaluate the current status of mechanical thrombectomy volumes in the United States, the number of patients in the Medicare fee-for-service database who underwent mechanical thrombectomy in 2016 was assessed. The specialty backgrounds of the various providers who performed mechanical thrombectomy were analyzed. Procedure volumes for intracranial stenting, embolization, and vertebral augmentation procedures were assessed.RESULTSFrom 2013 to 2017, the total numbers of mechanical thrombectomy procedures for acute ischemic stroke were 19 in 2013 and 111 in 2017. The total volume of mechanical thrombectomy procedures in the Medicare fee-for-service population in 2016 was 7479. For intracranial endovascular procedures, 20,850 were performed in the U.S. Medicare population in 2015 and 22,511 in 2016. Radiologists performed 45% of procedures in 2016; neurosurgeons, 41%; and neurologists, 11%. When the total numbers of percutaneous brain and spine procedures were combined, radiologists performed 41%; neurosurgeons, 23%; and neurologists, 3%. In 2016, there were a total of 220 active NIR staff at the NIR programs with rotating residents or fellows. In these programs, 49% of staff members were neuroradiologists, 41% were neurosurgeons, and 10% were neurologists. Of the 72 NIR departments with confirmed rotating fellows or residents, 14 had only neuroradiologists on staff, six had only neurosurgeons, and one had only neurologists.CONCLUSIONIncreasing radiology resident interest and participation in NIR should ensure a steady influx of radiologists into the field, continuing the strong tradition of radiology participation, leadership, and innovation in NIR.

Objective: Mechanical thrombectomy after acute ischemic stroke has been shown to improve clinical outcomes. Data on short-term hospitalization outcomes after thrombectomy are needed. Our objective was to quantify 30- and 90-day readmissions after thrombectomy and identify factors associated with readmissions. Methods: Retrospective observational analysis of adult patients hospitalized between January and November 2014, using data from the 2014 Nationwide Readmissions Database. Readmission rates were calculated and examined according to patient, clinical, and hospital characteristics using descriptive statistics. Weighted unconditional logistic regression models estimated the odds of readmission and examine the associations between select characteristics and readmission. Results: 4850 individuals who underwent mechanical thrombectomy for acute ischemic stroke in 2014 were eligible for 30-day readmissions analyses. The nonelective readmission rate was 12.5% at 30 days, 20.7% at 90 days. Sepsis and stroke were the most common reasons for readmission. Female sex (adjusted odds ratio [AOR] 1.34, 1.02-1.77 at 30 days), discharge to inpatient postacute care facility (AOR 1.61, 1.07-2.41 at 30 days, AOR 1.99, 1.47-2.69 at 90 days), and longer initial length of stay (AOR 1.52, 1.04-2.23 at 30 days, AOR 1.67, 1.14-2.43 at 90 days) were associated with a higher likelihood of readmission. Thrombectomy complications were rare and not associated with readmission. Conclusions: 1 in 8 thrombectomy patients had a short-term readmission in 2014. Characteristics suggestive of a complicated hospital course or greater physical disability were the primary predictors of readmission. This study provides preliminary data for evaluations of the public health impact of mechanical thrombectomy in real world settings.