Population analysis of ischemic stroke burden and risk factors in the United States in the pre- and post-mechanical thrombectomy eras.

OBJECTIVES: To provide an updated analysis of the burden of ischemic stroke in the United States. MATERIALS AND METHODS: Using the Global Burden of Disease database, we estimated age-standardized, population-adjusted rates of incidence, prevalence, mortality, and disability-adjusted life years from 2010 to 2019, with regional comparisons. Deaths and disability-adjusted life years were compared in 2010-2014 and 2015-2019 to assess the potential effect of increased mechanical thrombectomy use. The attributable, disability-adjusted life years for twenty risk factors were estimated, ranked, and trended. RESULTS: Incident ischemic strokes decreased by 11.4 % across the study period from 65.7 (55.9-77.3) to 58.2 (49.0-69.5) per 100,000. Prevalence (-8.2 %), mortality (-1.9 %), and disability-adjusted life years (-4.4 %) all declined. All regions showed reductions in all burden measures, with the South consistently having the highest burden yet the largest reduction in incidence (-12.6 %) and prevalence (-10.5 %). Deaths (p < 0.0001) and DALYs (p < 0.0001) significantly differed between the pre- and post-mechanical thrombectomy eras. Total attributable disability-adjusted life years for all risk factors decreased from 304.7 (258.5-353.2) in 2010 to 288.9 (242.2-337.2) in 2019. In 2019, the risk factors with the most disability-adjusted life years were hypertension, hyperglycemia, and obesity with no state-based differences. Across the study period, disability-adjusted life years attributable to leading risk factors decreased among men but decreased less or increased among women. CONCLUSIONS: The burden of ischemic stroke decreased during the study period. Declines in deaths and disability-adjusted life years suggest a mitigating impact of mechanical thrombectomy. While disability-adjusted life years attributable to leading risk factors decreased, sex-based disparities were observed.

Minimizing blood loss with direct percutaneous polymethylmethacrylate embolization before corpectomy for vascular spinal tumors.

Background: Standard surgical treatment for vascular spinal tumors, including renal cell carcinomas and hemangiomas, may result in significant blood loss despite preoperative arterial tumor embolization. Methods: This is a retrospective review of 12 patients who underwent direct percutaneous polymethylmethacrylate embolization (DPPE) with or without feeding artery embolization before partial or complete corpectomy for the resection of vascular spinal tumors (2013-2018). Estimated blood loss (EBL) was compared to the blood loss reported in the literature and to patients receiving standard arterial embolization before surgery. Results: The mean EBL for 12 patients was 1030 mL; three of 12 patients required blood transfusions. For the single level corpectomies, the EBL ranged from 100 mL to 3900 mL (mean 640 mL). This mean blood loss was not increased in patients receiving only DPPE preoperatively versus those patients receiving preoperative arterial embolization in addition to DPPE (1005 vs. 1416 mL); in fact, the EBL was significantly reduced for those undergoing DPPE alone. Conclusion: In this initial study, nine patients treated with DPPE embolization alone before spinal tumor resection demonstrated reduction of intraoperative blood loss compared to three patients having arterial embolization with DDPE.

Initial experience with transcarotid arterial revascularization with flow reversal in the management of symptomatic carotid stenosis.

OBJECTIVE: The aim of this study was to evaluate the efficacy of transcarotid arterial revascularization (TCAR) as a viable intervention in the treatment of symptomatic carotid artery stenosis. METHODS: The authors performed a retrospective review of prospectively collected data of the first 62 consecutive patients treated at Rhode Island Hospital in Providence, Rhode Island, who underwent a TCAR for symptomatic carotid artery stenosis between November 11, 2020, and March 31, 2022. Relevant demographic, comorbidity, and perioperative data were extracted through retrospective chart review. Patients with asymptomatic carotid artery stenosis were excluded. The authors also evaluated patients using pertinent physiological and anatomical high-risk criteria as described in the ROADSTER trial. Risk factors were aggregated to form a composite risk total for every patient. The primary outcome of this study was the 30-day adverse outcome rate of stroke, myocardial infarction, and/or death. Periprocedural stroke was identified by clinical symptoms and radiographic findings. Secondary endpoints included device and procedural success, 30-day mortality, 30-day stroke rate, and postoperative complications. RESULTS: The authors analyzed the first 62 patients with > 50% symptomatic carotid artery stenosis who underwent TCAR at their institution. The mean age of the cohort was 71.5 years, and the cohort was predominantly male (67.7%). The most common high-risk medical criteria were age older than 75 years (45.3%) and severe coronary artery disease (13.6%). The most common anatomical high-risk criteria were high bifurcation (35.1%) and contralateral stenosis requiring treatment within 30 days (15.8%). Fifty percent of patients had at least 1 medical high-risk criterion, 50% had at least 1 anatomical risk criterion, and 82% of patients had 2 or more high-risk criteria of any kind. Among this group, all patients (100%) underwent successful revascularization, with 1 (1.6%) requiring intraprocedural conversion to carotid endarterectomy. Postprocedurally, there was 1 nondisabling stroke (1.6%) and 3 deaths (4.8%) within 30 days of the procedure, with only 1 death directly attributable to the procedure. One patient (1.6%) experienced a neck hematoma. In total, 4 patients (6.5%) experienced a major complication. The overall complication rate was 8.0%. CONCLUSIONS: The authors' initial experience with TCAR suggests that it might provide an effective alternative to carotid endarterectomy and carotid artery stenting in the management of symptomatic carotid stenosis in patients with high-risk anatomical and medical characteristics.

Recurrence risk in symptomatic intracranial stenosis treated medically in the real world.

BACKGROUND: The risk of early recurrence in medically treated patients with intracranial atherosclerotic stenosis (ICAS) may differ in clinical trials versus real-world settings. Delayed enrollment may contribute to lower event rates in ICAS trials. We aim to determine the 30-day recurrence risk in a real-world setting of symptomatic ICAS. METHODS: We used a comprehensive stroke center stroke registry to identify hospitalized patients with acute ischemic stroke or TIA due to symptomatic 50-99% ICAS. The outcome was recurrent stroke within 30 days. We used adjusted Cox regression models to identify factors associated with increased recurrence risk. We also performed a comparison of 30-day recurrent stroke rates in real world cohorts and clinical trials. RESULTS: Among 131 hospitalizations with symptomatic 50-99% ICAS over 3 years, 80 hospitalizations of 74 patients (mean age 71.6 years, 55.41% men) met the inclusion criteria. Over 30 days, 20.6 % had recurrent stroke; 61.5% (8/13) occurred within first 7 days. The risk was higher in patients not receiving dual antiplatelet therapy (HR 3.92 95% CI 1.30-11.84, p = 0.015) and hypoperfusion mismatch volume >3.5 mL at a T max>6 s threshold (HR 6.55 95% CI 1.60-26.88, p < 0.001). The recurrence risk was similar to another real world ICAD cohort (20.2%), and higher than that seen in clinical trials (2.2%-5.7%), even in those treated with maximal medical treatment or meeting inclusion criteria for trials. CONCLUSIONS: In patients with symptomatic ICAS, the real-world recurrence of ischemic events is higher than that seen in clinical trials, even in subgroups receiving the same pharmacological treatment strategies.

Transradial Carotid Artery Stenting Using Walrus Balloon Guide Catheter: Technical Aspects and Clinical Outcome.

BACKGROUND: Despite an overall surge in transradial access (TRA) for neurointerventional procedures, the feasibility and safety of TRA carotid artery angioplasty and stenting using balloon guide catheters (BGCs) through a short 8-Fr sheath have not been studied. In this study, we present our experience of using Walrus BGC through TRA for carotid artery stent placement. OBJECTIVE: To define the safety and efficacy of using a balloon guide catheter for carotid stenting by a transradial approach. METHODS: Our prospectively maintained retrospective database was reviewed, and consecutive patients were identified who underwent elective carotid artery stenting through TRA using Walrus BGC between January 2021 and June 2022. Demographics, procedural details including access site complications, the rate of radial to groin conversion, and procedure-related transient ischemic attack or stroke were reviewed. RESULTS: Twenty patients were identified who underwent carotid artery angioplasty and stenting through TRA Walrus BGC use; the mean age was 66 years (range 42-89), and 67% were male. A short 8-Fr sheath was used in all patients without any complications. Two of 20 patients required TRA conversion to transfemoral access, both secondary to severe spasm of the radial artery after initial access inhibiting further advancement of the Walrus BGC. CONCLUSION: Use of Walrus BGC by TRA through an 8-Fr sheath for carotid artery stenting is safe and feasible with a low rate of conversion to transfemoral access and no access site complications.

Dual antiplatelet use in the management of COVID-19 associated acute ischemic stroke reocclusion.

INTRO: SARS-CoV-2 (COVID-19) infection is associated with acute ischemic stroke (AIS), which may be due to a prothrombotic state. Early reports have suggested high rates of reocclusion following mechanical thrombectomy (MT) with poor radiographic and clinical outcomes. We report our early experience using intra-procedural antithrombotics to address SARS-CoV-2 reocclusion. METHODS: We identified 6 patients that experienced early reocclusion after MT for COVID-19-associated AIS through retrospective chart review abstracting their basic demographics, COVID-19 status, and stroke management. All these patients were treated after reocclusion with aspirin and cangrelor intra-procedurally, the latter of which was converted to ticagrelor post-procedurally. Some patients additionally received argatroban infusion intraprocedurally. RESULTS: Mean age was 54. There were 3 post-procedural and 3 intra-procedural re-occlusions. After repeat thrombectomy and treatment with aspirin and cangrelor, those with post-procedure reocclusion did not show further reocclusion, while those with intra-procedural reocclusion showed radiographic improvement with intraprocedural cangrelor administration. Outcomes for these patients were poor, with a median mRS of 4. Two patients developed petechial hemorrhage of their stroke which was managed conservatively, and one developed a retroperitoneal hemorrhage from femoral access requiring transfusion. There were no patients who developed new parenchymal hematomas. CONCLUSION: COVID-19 AIS may be associated with a hypercoagulable state which risks malignant reocclusion complicating MT. We found antithrombotic treatment periprocedural cangrelor with or without argatroban transitioned to oral aspirin with ticagrelor to be a viable method for management of these patients.

Long-term effect of field triage on times to endovascular treatment for emergent large vessel occlusion.

BACKGROUND: Delays to endovascular therapy (EVT) for stroke may be mitigated with direct field triage to EVT centers. We sought to compare times to treatment over a 5.5 year span between two adjacent states, one with field triage and one without, served by a single comprehensive stroke center (CSC). METHODS: During the study period, one of the two states implemented severity-based triage for suspected emergent large vessel occlusion, while in the other state, patients were transported to the closest hospital regardless of severity. We compared times to treatment and clinical outcomes between these two states. We also performed a matched pairs analysis, matching on date treated and distance from field to CSC. RESULTS: 639 patients met the inclusion criteria, 407 in State 1 (with field triage) and 232 in State 2 (without field triage). In State 1, scene to EVT decreased 6% (or 8.13 min, p=0.0004) every year but no decrease was observed for State 2 (<1%, p=0.94). Cumulatively over 5.5 years, there was a reduction of 43 min in time to EVT in State 1, but no change in State 2. Lower rates of disability were seen in State 1, both for the entire cohort (all OR 1.22, 95% CI 1.07 to 1.40, p=0.0032) and for those independent at baseline (1.36, 95% CI 1.15 to 1.59, p=0.0003). CONCLUSIONS: Comparing adjacent states over time, the implementation of severity-based field triage significantly reduced time to EVT.

Safety of Sheathless Transradial Balloon Guide Catheter Placement for Acute Stroke Thrombectomy.

BACKGROUND: Transradial access has been described for mechanical thrombectomy in acute stroke, and proximal balloon occlusion has been shown to improve recanalization and outcomes. However, sheathed access requires a larger total catheter diameter at the access site. We aimed to characterize the safety of sheathless transradial balloon guide catheter use in acute stroke intervention. METHODS: Consecutive patients who underwent sheathless right-sided transradial access for thrombectomy with a balloon guide catheter were identified in a prospectively collected dataset from 2019 to 2021. Demographics, procedure details, and short-term outcomes were collected and reported with descriptive statistics. RESULTS: A total of 48 patients (20 women) with a mean age of 72.3 years were identified. Of patients, 56.3% had occlusions in the left-sided circulation; 35 (72.9%) had M1 occlusions, 7 (14.6%) had M2 occlusions, and 6 (12.5%) had internal carotid artery occlusions. Tissue plasminogen activator was administered to 16 (33.3%) patients. Five (10.4%) patients underwent intraprocedural carotid stenting. The cohort had successful reperfusion after a median of 1 (interquartile range: 1, 2) pass. Median time from access to recanalization was 31 (interquartile range: 25, 53) minutes. A postprocedural Thrombolysis In Cerebral Infarction score of ≥2b was achieved in 46 (95.8%) patients. Five patients had wrist access site hematomas. All hematomas resolved with warm compresses, and no further intervention was required. CONCLUSIONS: Sheathless radial access using a balloon guide catheter may be safely performed for acute ischemic stroke with excellent radiographic outcomes. Further investigation is warranted to evaluate the comparative effectiveness of sheathless compared with sheathed transradial balloon guide access.

Awake, Endoscopic Revision Surgery for Lumbar Pseudarthrosis After Transforaminal Lumbar Interbody Fusion: Technical Notes.

OBJECTIVE: We sought to evaluate the feasibility for awake, endoscopic treatment of lumbar pseudarthrosis after a transforaminal lumbar interbody fusion (TLIF). METHODS: A 71-year-old male with severe cardiac disease, determined to be high risk for general anesthesia, presented with mechanical back pain and a L3-4 pseudarthrosis and L3 pedicle screw loosening after a L3-5 TLIF. An awake, transforaminal endoscopic redo diskectomy and TLIF procedure were performed by removing residual disk material adjacent to the previous "PEEK" (polyetheretherketone) interbody spacer and placing allograft, bone morphogenetic protein, and an expandable titanium interbody device adjacent to the PEEK cage. RESULTS: At 1-year follow-up, preoperative visual analog scale for back pain and Oswestry disability index improved from 7 and 38% to 1 and 2%. The 1-year follow-up radiograph showed stable interbody placement and no further screw loosening. CONCLUSIONS: A minimally invasive, awake procedure is presented for the treatment of pseudarthrosis after TLIF.

Transforaminal Endoscopic Approach for Lumbar Extraforaminal Synovial Cysts: Technical Note.

OBJECTIVE: Lumbar facet cysts are commonly seen in degenerative lumbar conditions causing stenosis and radiculopathy. Extraforaminal lumbar facet cysts are a rare entity and present a surgical challenge because of their location. Transforaminal endoscopic spine surgery is an emerging technique in spine surgery but has never been described as a treatment option for lumbar radiculopathy in the setting of extraforaminal lumbar facet cyst. METHODS: A technique for the transforaminal endoscopic treatment of an extraforaminal lumbar facet cyst is presented in 2 patients. We retrospectively reviewed 321 cases of patients who underwent transforaminal endoscopic surgery in a 4-year period with a minimum follow-up of 2 years. RESULTS: A series of 2 patients who underwent transforaminal endoscopic foraminotomy and cyst resection procedures for extraforaminal lumbar facet cysts between 2014 and 2017 is presented: A 51-year-old woman with a right L4-5 extraforaminal cyst improved from a preoperative visual analog scale (VAS) of 7 and Oswestry disability index (ODI) of 26 to a 1-year postoperative VAS score of 2 and ODI of 4; and a 71-year-old woman with a left L5-S1 extraforaminal cyst improved from a preoperative VAS of 7 and ODI of 30 to a 1-year postoperative VAS score of 2 and ODI of 6. CONCLUSIONS: Transforaminal endoscopic surgery for a lumbar radiculopathy in the setting of an extraforaminal lumbar facet cyst is presented as a unique minimally invasive approach for the treatment of extraforaminal lumbar facet cyst that avoids facet resection and fusion.

Minimally invasive approach to non-missile penetrating spinal injury with resultant retained foreign body: A case report and review of the literature.

Non- missile penetrating spinal injury (NMPSI) is a rare entity in North America and as a result there is no clear treatment paradigm. According to the literature, NMPSI causes serious acute neurological deficits and can also lead to devastating delayed complications in cases of untreated retained foreign bodies (RFB). In this report we present an acute case of NMPSI to the thoracic spine resulting in RFB treated by operative removal using minimally invasive fluoroscopic technique. While in prior published cases of NMPSI operative intervention was accomplished through laminectomy, our case presents an alternative, less invasive approach which may results in shorter recovery time. We also review the literature on NMPSI, including reports on both acute cases and chronic presentation due to RFBs. Based on this review, we conclude that NMPSI associated with RFB should be managed with operative intervention.

Intraoperative Computed Tomography Navigation-Assisted Resection of Symptomatic Intramedullary Spinal Cord Cavernoma: A Technical Note and Case Report.

BACKGROUND: Intramedullary spinal cord cavernous malformations (ISCCMs) are a rare entity. Most commonly, ISCCMs present with neurologic decline from lesion hemorrhage, which can be catastrophic and irreversible irrespective of surgical intervention. Given the challenging anatomic location of these lesions in highly critical neurologic areas, precise surgical localization and visualization is necessary to limit collateral damage during resection particularly for deep ISCCMs that do not present to a pial surface. CASE DESCRIPTION: We present a case of a 54-year-old man who presented with incomplete paraplegia after hemorrhage of a deep ISCCM at T11. Surgical resection was undertaken using intraoperative computed tomography (CT) navigation assistance autofused with high-resolution preoperative magnetic resonance imaging for precise intramedullary lesion targeting and localization for myelotomy. Complete resection was demonstrated on postoperative imaging. At a 6-week follow-up appointment, the patient endorsed return of his bladder function and was noted to have some return of motor function to his left foot with 3 of 5 dorsiflexion. At 4 months, he had improved to 3 of 5 proximal, 4 of 5 distal on the left and 2 of 5 proximal, and 3 of 5 distal on the right. CONCLUSIONS: The approach represents a novel application of intraoperative CT navigation assistance in the resection of deep ISCCMs.

Door-in-Door-Out Time at Primary Stroke Centers May Predict Outcome for Emergent Large Vessel Occlusion Patients.

Background and Purpose- Interfacility transfers for thrombectomy in stroke patients with emergent large vessel occlusion (ELVO) are associated with longer treatment times and worse outcomes. In this series, we examined the association between Primary Stroke Center (PSC) door-in to door-out (DIDO) times and outcomes for confirmed ELVO stroke transfers and factors that may modify the interaction. Methods- We retrospectively identified 160 patients transferred to a single Comprehensive Stroke Center (CSC) with anterior circulation ELVO between July 1, 2015 and May 30, 2017. We included patients with acute occlusions of the internal carotid artery or proximal middle cerebral artery (M1 or M2 segments), with a National Institutes of Health Stroke Scale score of ≥6. Workflow metrics included time from onset to recanalization, PSC DIDO, interfacility transfer time, CSC arrival to arterial puncture, and arterial puncture to recanalization. Primary outcome measure was National Institutes of Health Stroke Scale at discharge and modified Rankin Scale (mRS) score at 90 days. Results- The median (Q1-Q3) age and National Institutes of Health Stroke Scale of the 130 ELVO transfers analyzed was 75 (64-84) and 17 (11-22). Intravenous alteplase was administered to 64% of patients. Regarding specific workflow metrics, median (Q1-Q3) times (in minutes) were 241 (199-332) for onset to recanalization, 85 (68-111) for PSC DIDO, 26 (17-32) for interfacility transport, 21 (16-39) for CSC door to arterial puncture, and 24 (15-35) for puncture to recanalization. Median discharge National Institutes of Health Stroke Scale score was 5 (2-16), and 46 (35%) patients had a favorable outcome at 90 days. Complete reperfusion (modified Thrombolysis in Cerebral Ischemia 2c/3) modified the deleterious association of DIDO on outcome. Conclusions- For patients diagnosed with ELVO at a PSC who are being transferred to a CSC for thrombectomy, longer DIDO times may have a deleterious effect on outcomes and may represent the single biggest modifiable factor in onset to recanalization time. PSCs should make efforts to decrease DIDO and routine use of DIDO as a performance measure is encouraged.

Myelin water fraction changes in febrile seizures.

OBJECTIVE: The objective of this feasibility study was to investigate whether myelin water fraction (MWF) patterns can differentiate children presenting with febrile seizures who will go on to develop nonfebrile epilepsy from those who will not. PATIENTS AND METHODS: As part of a prospective study of myelination patterns in pediatric epilepsy, seven subjects with febrile seizures underwent magnetic resonance imaging (MRI) including the following standard sequences-T1-weighted, T2-weighted, fluid-attenuated inversion recovery (FLAIR)-and an additional experimental sequence, multicomponent-derived equilibrium single-pulse observation of T1 and T2 (mcDESPOT) to quantify MWF. For each of these subjects, MWF maps were derived and compared with an age-matched population-averaged MWF atlas. RESULTS: All seven subjects (<5 years old) initially presented with febrile seizures. Of the seven, four had complex seizures and three had simple seizures. All of the children with simple febrile seizures had higher MWF compared with model-derived controls and did not develop epilepsy. All of the children with complex febrile seizures had lower MWF than their model-derived control, and two of these subjects later developed epilepsy. CONCLUSION: This is the first study in which MWF maps were used to study children with febrile *seizures. This data suggests that relatively higher or stable MWF compared with normative data indicates a lower risk of nonfebrile epilepsy while relatively lower MWF may indicate a pathological condition that could lead to nonfebrile epilepsy.

Local failure and vertebral body fracture risk using multifraction stereotactic body radiation therapy for spine metastases.

PURPOSE: Single-fraction radiation surgery for spine metastases is highly effective. However, a high rate (20-39%) of vertebral body fracture (VBF) has been associated with large, single-fraction doses. We report our experience using multifraction stereotactic body radiation therapy (SBRT). METHODS AND MATERIALS: All patients who were treated with multifraction SBRT for spine metastases at our institution between 2009 and 2017 were retrospectively analyzed. SBRT was delivered in 2 to 5 fractions using the Cyberknife System (Accuray, Sunnyvale, CA). Patients were followed clinically and with magnetic resonance imaging every 3 to 6 months. Local control, complications (including VBF), and overall survival were evaluated. Patient, disease, and treatment variables were analyzed for a statistical association with outcomes. RESULTS: A total of 83 patients were treated to 98 spine lesions with a median follow-up of 7.6 months. Histologies included non-small cell lung cancer (NSCLC; 24%), renal cell carcinoma (RCC; 18%), and breast cancer (12%). Surgery or vertebroplasty were performed before SBRT in 21% of cases. Patients received a median SBRT dose of 24 Gy in a median of 3 fractions. Local control was 93% at 6 months and 84% at 1 year. Higher prescribed dose, higher biologic effective dose, higher minimum dose to 90% of the planning target volume, tumor histology, and smaller tumor volume predicted improved local control. The cumulative dose was 23 Gy versus 26 Gy for patients with and without failure (P = .02), higher biologic effective dose 39 Gy versus 46 Gy, (P = .01), and higher minimum dose to 90% of the planning target volume 23 Gy versus 26 Gy (P = .03). VBF occurred in 4.2% of all cases and 5.3% of those without surgery or vertebroplasty prior to SBRT. Only preexisting VBF predicted risk of post-SBRT VBF (P < .01). CONCLUSIONS: Multifraction SBRT results in a high local control rate for metastatic spinal disease with a low VBF rate, which suggests a favorable therapeutic ratio compared with single-fraction SBRT.

Impact of target location on the response of trigeminal neuralgia to stereotactic radiosurgery.

OBJECT: The authors evaluate the impact of target location on the rate of pain relief (PR) in patients with intractable trigeminal neuralgia (TN) undergoing stereotactic radiosurgery (SRS). METHODS: The authors conducted a retrospective review of 99 patients with idiopathic TN who were identified from a prospectively maintained database and were treated with SRS targeting the dorsal root entry zone with a maximum dose of 80 Gy. Targeting of the more proximal portion of a trigeminal nerve with the 50% isodose line overlapping the brainstem was performed in 36 patients (proximal group). In a matched group, 63 patients received SRS targeting the 20% isodose line tangential to the emergence of the brainstem (distal group). The median follow-up time was 33 months (range 6-124 months). RESULTS: The actuarial rate of maintenance of Barrow Neurological Institute (BNI) Pain Score I-IIIa was attained in 89% of patients at 1 year, 81% at 2 years, and 69% at 4 years, respectively, after SRS. Kaplan-Meier analysis revealed that durability of PR was only associated with the proximal location of the radiosurgical target (log-rank test, p = 0.018). Radiosurgery-induced facial numbness (BNI Score II or III) developed in 35 patients, which was significantly more frequent in the proximal group (19 patients [53%] compared with 16 [25%] in the distal group [p = 0.015]). CONCLUSIONS: The radiosurgical target appears to affect the duration of pain relief in patients with idiopathic trigeminal neuralgia with the target closer to the brainstem affording extended pain relief. However, the proximal SRS target was also associated with an increased risk of mild to moderate facial numbness.

Minimally invasive treatment of intracerebral hemorrhage with magnetic resonance-guided focused ultrasound.

OBJECT: Intracerebral hemorrhage (ICH) is a major cause of death and disability throughout the world. Surgical techniques are limited by their invasive nature and the associated disability caused during clot removal. Preliminary data have shown promise for the feasibility of transcranial MR-guided focused ultrasound (MRgFUS) sonothrombolysis in liquefying the clotted blood in ICH and thereby facilitating minimally invasive evacuation of the clot via a twist-drill craniostomy and aspiration tube. METHODS AND RESULTS: In an in vitro model, the following optimum transcranial sonothrombolysis parameters were determined: transducer center frequency 230 kHz, power 3950 W, pulse repetition rate 1 kHz, duty cycle 10%, and sonication duration 30 seconds. Safety studies were performed in swine (n = 20). In a swine model of ICH, MRgFUS sonothrombolysis of 4 ml ICH was performed. Magnetic resonance imaging and histological examination demonstrated complete lysis of the ICH without additional brain injury, blood-brain barrier breakdown, or thermal necrosis due to sonothrombolysis. A novel cadaveric model of ICH was developed with 40-ml clots implanted into fresh cadaveric brains (n = 10). Intracerebral hemorrhages were successfully liquefied (> 95%) with transcranial MRgFUS in a highly accurate fashion, permitting minimally invasive aspiration of the lysate under MRI guidance. CONCLUSIONS: The feasibility of transcranial MRgFUS sonothrombolysis was demonstrated in in vitro and cadaveric models of ICH. Initial in vivo safety data in a swine model of ICH suggest the process to be safe. Minimally invasive treatment of ICH with MRgFUS warrants evaluation in the setting of a clinical trial.

Optimal imaging of in vitro clot sonothrombolysis by MR-guided focused ultrasound.

BACKGROUND AND PURPOSE: As magnetic resonance-guided focused ultrasound (MRgFUS) sonothrombolysis relies on mechanical rather than thermal mechanisms to achieve clot lysis, thermometry is not useful for the intraoperative monitoring of clot breakdown by MRgFUS. Therefore, the purpose of this study was to evaluate the optimum imaging sequence for sonothrombolysis. METHODS: In vitro blood drawn from 6 healthy volunteers was imaged using T1, T2 spin-echo, and T2 gradient-echo (GRE) sequences both before and after sonication using an Insightec ExAblate 4000 FUS transducer. Signal intensities of the three MR imaging sequences were measured and normalized to background signal for each time point. Representative samples of the pre- and postsonication clot were also sent to pathology for hematologic analysis. RESULTS: After sonication, the clot in the treatment tube was fully lysed as evidenced by physical and hematologic evaluation. The difference between pre- and postsonicated normalized signal intensity ratios demonstrated statistical significance only on T2 and GRE sequences (P < .001). However, significant blooming artifact limited interpretation on all GRE images. CONCLUSION: T2 is the most appropriate sequence for the evaluation of mechanical MRgFUS sonothrombolysis of an in vitro clot. These findings are consistent across the oxidative states of clot up to 48 hours.