Publications by authors named "Neeraj Chaudhary"

132 Publications

Skull Base Neurointerventional Techniques.

Neuroimaging Clin N Am 2021 Nov;31(4):649-664

Department of Radiology, University of Michigan, 1500 E. Medical Center Dr, B1D330A, Ann Arbor, MI 48109, USA.

Neurodiagnostic and neurointerventional radiology (NIR) play a central role in the diagnosis and treatment of skull base disorders. Noninvasive imaging modalities, including computed tomography and magnetic resonance imaging, are important in lesion localization, evaluation of lesion extent, and diagnosis, but cannot always be definitive. Image-guided skull base biopsy and percutaneous and endovascular treatment options are important tools in the diagnosis and treatment of head, neck, and skull base disorders. NIR plays an important role in the treatment of vascular disorders of the skull base. This article summarizes the imaging evaluation and interventional therapies pertinent to the skull base.
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http://dx.doi.org/10.1016/j.nic.2021.06.007DOI Listing
November 2021

Thrombus Histology as It Relates to Mechanical Thrombectomy: A Meta-Analysis and Systematic Review.

Neurosurgery 2021 Nov;89(6):1122-1131

Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.

Background: Appropriate thrombus-device interaction is critical for recanalization. Histology can serve as a proxy for mechanical properties, and thus inform technique selection.

Objective: To investigate the value of histologic characterization, we conducted a systematic review and meta-analysis on the relationship between thrombus histology and recanalization, technique, etiology, procedural efficiency, and imaging findings.

Methods: In this meta-analysis, we identified studies published between March 2010 and March 2020 reporting findings related to the histologic composition of thrombi in large vessel occlusion stroke. Studies with at least 10 patients who underwent mechanical thrombectomy using stent retriever or aspiration were considered. Only studies in which retrieved thrombi were histologically processed were included. Patient-level data were requested when data could not be directly extracted. The primary outcome assessed was the relationship between thrombus histology and angiographic outcome.

Results: A total of 22 studies encompassing 1623 patients met inclusion criteria. Clots associated with good angiographic outcome had higher red blood cell (RBC) content (mean difference [MD] 9.60%, 95% CI 3.85-15.34, P = .008). Thrombi retrieved by aspiration had less fibrin (MD -11.39, 95% CI -22.50 to -0.27, P = .046) than stent-retrieved thrombi. Fibrin/platelet-rich clots were associated with longer procedure times (MD 13.20, 95% CI 1.30-25.10, P = .037). Hyperdense artery sign was associated with higher RBC content (MD 14.17%, 95% CI 3.07-25.27, P = .027). No relationship was found between composition and etiology.

Conclusion: RBC-rich thrombi were associated with better recanalization outcomes and shorter procedure times, suggesting that preinterventional compositional characterization may yield important prognostic and therapeutic guidance.
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http://dx.doi.org/10.1093/neuros/nyab366DOI Listing
November 2021

Transcranial Magnetic Resonance-Guided Histotripsy for Brain Surgery: Pre-clinical Investigation.

Ultrasound Med Biol 2022 Jan 4;48(1):98-110. Epub 2021 Oct 4.

Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA. Electronic address:

Histotripsy has been previously applied to target various cranial locations in vitro through an excised human skull. Recently, a transcranial magnetic resonance (MR)-guided histotripsy (tcMRgHt) system was developed, enabling pre-clinical investigations of tcMRgHt for brain surgery. To determine the feasibility of in vivo transcranial histotripsy, tcMRgHt treatment was delivered to eight pigs using a 700-kHz, 128-element, MR-compatible phased-array transducer inside a 3-T magnetic resonance imaging (MRI) scanner. After craniotomy to open an acoustic window to the brain, histotripsy was applied through an excised human calvarium to target the inside of the pig brain based on pre-treatment MRI and fiducial markers. MR images were acquired pre-treatment, immediately post-treatment and 2-4 h post-treatment to evaluate the acute treatment outcome. Successful histotripsy ablation was observed in all pigs. The MR-evident lesions were well confined within the targeted volume, without evidence of excessive brain edema or hemorrhage outside of the target zone. Histology revealed tissue homogenization in the ablation zones with a sharp demarcation between destroyed and unaffected tissue, which correlated well with the radiographic treatment zones on MRI. These results are the first to support the in vivo feasibility of tcMRgHt in the pig brain, enabling further investigation of the use of tcMRgHt for brain surgery.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2021.09.008DOI Listing
January 2022

The Two Faces of Estrogen in Experimental Hemorrhagic Stroke.

Transl Stroke Res 2021 Sep 16. Epub 2021 Sep 16.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.

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http://dx.doi.org/10.1007/s12975-021-00942-0DOI Listing
September 2021

Commentary: Neuroendovascular Management of Acute Ischemic Basilar Strokes: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2021 09;21(4):E348-E349

Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.

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http://dx.doi.org/10.1093/ons/opab251DOI Listing
September 2021

Thrombectomy in special populations: report of the Society of NeuroInterventional Surgery Standards and Guidelines Committee.

J Neurointerv Surg 2021 Jul 8. Epub 2021 Jul 8.

Department of Radiology, UCSF, San Francisco, California, USA

Background: The purpose of this guideline is to summarize the data available for performing mechanical thrombectomy (MT) for emergent large vessel occlusion (ELVO) stroke in special populations not typically included in large randomized controlled clinical trials, including children, the elderly, pregnant women, patients who have recently undergone surgery, and patients with thrombocytopenia, collagen vascular disorders, and endocarditis.

Methods: We performed a literature review for studies examining the indications, efficacy, and outcomes for patients undergoing MT for ischemic stroke aged <18 years and >80 years, pregnant patients, patients who have recently undergone surgery, and those with thrombocytopenia, collagen vascular diseases, or endocarditis. We graded the quality of the evidence.

Results: MT can be effective for the treatment of ELVO in ischemic stroke for patients over age 80 years and under age 18 years, thrombocytopenic patients, pregnant patients, and patients with endocarditis. While outcomes are worse compared to younger patients and those with normal platelet counts (respectively), there is still a benefit in the elderly (in both mRS and mortality). Data are very limited for patients with collagen vascular diseases; although diagnostic cerebral angiography carries increased risks, MT may be appropriate in carefully selected patients in whom untreated ELVO would likely result in disabling or fatal outcome.
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http://dx.doi.org/10.1136/neurintsurg-2021-017888DOI Listing
July 2021

White Matter Survival within and around the Hematoma: Quantification by MRI in Patients with Intracerebral Hemorrhage.

Biomolecules 2021 06 18;11(6). Epub 2021 Jun 18.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA.

White matter (WM) injury and survival after intracerebral hemorrhage (ICH) has received insufficient attention. WM disruption surrounding the hematoma has been documented in animal models with histology, but rarely in human ICH with noninvasive means, like magnetic resonance imaging (MRI). A few human MRI studies have investigated changes in long WM tracts after ICH remote from the hematoma, like the corticospinal tract, but have not attempted to obtain an unbiased quantification of WM changes within and around the hematoma over time. This study attempts such quantification from 3 to 30 days post ictus. Thirteen patients with mild to moderate ICH underwent diffusion tensor imaging (DTI) MRI at 3, 14, and 30 days. Fractional anisotropy (FA) maps were used to calculate the volume of tissue with FA > 0.5, both within the hematoma (lesion) and in the perilesional tissue. At day 3, the percentages of both lesional and perilesional tissue with an FA > 0.5 were significantly less than contralateral, unaffected, anatomically identical tissue. This perilesional contralateral difference persisted at day 14, but there was no significant difference at day 30. The loss of perilesional tissue with FA > 0.5 increased with increasing hematoma size at day 3 and day 14. All patients had some tissue within the lesion with FA > 0.5 at all time points. This did not decrease with duration after ictus, suggesting the persistence of white matter within the hematoma/lesion. These results outline an approach to quantify WM injury, both within and surrounding the hematoma, after mild to moderate ICH using DTI MRI. This may be important for monitoring treatment strategies, such as hematoma evacuation, and assessing efficacy noninvasively.
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http://dx.doi.org/10.3390/biom11060910DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234588PMC
June 2021

Assessing early erythrolysis and the relationship to perihematomal iron overload and white matter survival in human intracerebral hemorrhage.

CNS Neurosci Ther 2021 10 17;27(10):1118-1126. Epub 2021 Jun 17.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.

Aims: Iron released from lysed red blood cells within the hematoma plays a role in intracerebral hemorrhage (ICH)-related neurotoxicity. This study utilizes magnetic resonance imaging (MRI) to examine the time course, extent of erythrolysis, and its correlation with perihematomal iron accumulation and white matter loss.

Methods: The feasibility of assessing proportional erythrolysis using T2* MRI was examined using pig blood phantoms with specified degrees of erythrolysis. Fifteen prospectively enrolled ICH patients had MRIs (3-Tesla) at days 1-3, 14, and 30 (termed early, subacute, and late periods, respectively). Measurement was performed on T2*, 1/T2*, and fractional anisotropy (FA) maps.

Results: Pig blood phantoms showed a linear relationship between 1/T2* signal and percent erythrolysis. MRI on patients showed an increase in erythrolysis within the hematoma between the early and subacute phases after ICH, almost completing by day 14. Although perihematomal iron overload (IO) correlated with the erythrolysis extent and hematoma volume at days 14 and 30, perihematomal white matter (WM) loss significantly correlated with both, only at day 14.

Conclusion: MRI may reliably assess the portion of the hematoma that lyses over time after ICH. Perihematomal IO and WM loss correlate with both the erythrolysis extent and hematoma volume in the early and subacute periods following ICH.
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http://dx.doi.org/10.1111/cns.13693DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8446214PMC
October 2021

Mechanical Thrombectomy Improves Outcome for Large Vessel Occlusion Stroke after Cardiac Surgery.

J Stroke Cerebrovasc Dis 2021 Aug 19;30(8):105851. Epub 2021 May 19.

Departments of Neurosurgery, University of Michigan, Ann Arbor, Michigan. Electronic address:

Background: Stroke is a feared complication of cardiac surgery. Modern clot-retrieval techniques provide effective treatment for large vessel occlusion (LVO) strokes. The purpose of this study was to 1) report the incidence of LVO stroke after cardiac surgery at a large academic center, and 2) describe outcomes of postoperative LVO strokes.

Methods: All patients experiencing stroke within 30 days after undergoing cardiac surgery at a single center in 2014-2018 were reviewed. LVOs were identified through review of imaging and medical records, and their characteristics and clinical courses were examined.

Results: Over the study period, 7,112 cardiac surgeries, including endovascular procedures, were performed. Acute ischemic stroke within 30 days after surgery was noted in 163 patients (2.3%). Among those with a stroke, 51/163 (31.3%) had a CTA or MRA, and 15/163 (9.2%) presented with LVO stroke. For all stroke patients, the median time from surgery to stroke was 2 days (interquartile range, IQR, 0-6 days), and for patients with LVO, the median time from surgery to stroke was 4 days (IQR 0-6 days). The overall rate of postoperative LVO was 0.2% (95% CI 0.1-0.4%), though only 6/15 received thrombectomy. LVO patients receiving thrombectomy were significantly more likely to return to independent living compared to those managed medically (n = 4/6, 66.6% for mechanical thrombectomy vs. n = 0/9, 0% for medical management, P = .01). Of the 9 patients who did not get thrombectomy, 6 may currently be candidates for thrombectomy given new expanded treatment windows.

Conclusions: The rate of LVO after cardiac surgery is low, though substantially elevated above the general population, and the majority do not receive thrombectomy currently. Patients receiving thrombectomy had improved neurologic outcomes compared to patients managed medically. Optimized postoperative care may increase the rate of LVO recognition, and cardiac surgery patients and their caregivers should be aware of this effective therapy.
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http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2021.105851DOI Listing
August 2021

Stent-assisted coiling of cerebral aneurysms: Head to head comparison between the Neuroform Atlas and EZ stents.

Interv Neuroradiol 2021 Jun 28;27(3):353-361. Epub 2021 Jan 28.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.

Background: The Neuroform Atlas stent is thought to have features allowing for an improved stent delivery system. We aimed to provide a comparison of the Atlas and Neuroform EZ stents in patients treated with stent-assisted coiling.

Methods: Seventy-seven aneurysms treated with the Atlas stent and 77 aneurysms with similar characteristics treated with the EZ stent were retrospectively compared. Outcomes included angiographic occlusion per the Raymond-Roy (RR) scale, recanalization, retreatment and procedural complications.

Results: With the Atlas stent, technical success was 100% and immediate RR1 occlusion was 81.8%. Follow-up RR1 was achieved in 83.7%. The recanalization rate was 7% and the retreatment rate was 4.6%. The complication rate was 6.5% (new neurological deficit in 1.3%). With the EZ stent, technical success was 96%, immediate RR1 occlusion was 67.6% and follow-up RR1 was 67.6%. The recanalization rate was 12.7% and the retreatment rate was 14.1%. The complication rate was 10.4% (new neurological deficit in 2.6%). The rate of immediate RR1 occlusion was significantly higher with the Atlas stent ( = 0.03), and the rate of follow-up RR1 was nonsignificantly higher with the Atlas stent ( = 0.08). The retreatment rate was significantly lower with the Atlas stent ( = 0.009). There were no significant differences in the rates of recanalization ( = 0.5) and complications ( = 0.6).

Conclusions: Stent-assisted coiling with the Atlas stent is safe and effective and shows better immediate results as compared to the EZ stent, with improved overall follow-up outcomes.
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http://dx.doi.org/10.1177/1591019921989476DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8190941PMC
June 2021

Abdominal aortic aneurysm is associated with subarachnoid hemorrhage.

J Neurointerv Surg 2021 Aug 6;13(8):716-721. Epub 2020 Nov 6.

Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA

Background: Although intracranial aneurysms (IA) and abdominal aortic aneurysms (AAA) share similar risk factors, little is known about the relationship between them. Previous studies have shown an increased incidence of IA in patients with AAA, though the rate of subarachnoid hemorrhage (SAH) in patients with AAA has not been described.

Objective: To use claims data with longitudinal follow-up, to evaluate the incidence of aneurysmal SAH in patients diagnosed with AAA.

Methods: We examined longitudinally linked medical claims data from a large private insurer to determine rates of aneurysmal SAH (aSAH) and secured aSAH (saSAH) in 2004-2014 among patients with previously diagnosed AAA.

Results: We identified 62 910 patients diagnosed with AAA and compared them 5:1 with age- and sex-matched controls. Both populations were predominantly male (70.9%), with an average age of 70.8 years. Rates of hypertension (69.7% vs 50.6%) and smoking (12.8% vs 4.1%) were higher in the AAA group (p<0.0001) than in controls. Fifty admissions for aSAH were identified in patients with AAA (26/100 000 patient-years, 95% CI 19 to 44) and 115 admissions for aSAH in controls (7/100 000 years, 95% CI 6 to 9), giving an incidence rate ratio (IRR) of 3.6 (95% CI 2.6 to 5.0, p<0.0001) and a comorbidity-adjusted incidence rate ratio (IRR) of 2.8 (95% CI 1.9 to 3.9) for patients with AAA. The incidence of secured aneurysmal SAH was proportionally even higher in patients with AAA, 7 vs 2/100 000 years, IRR 4.5 (95% CI 3.2 to 6.3, p<0.0001).

Conclusion: SAH rate was elevated in patients with AAA, even after adjustment for comorbidities. Among risk factors evaluated, AAA was the strongest predictor for SAH. The relative contributions of common genetic and environmental risk factors to both diseases should be investigated.
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http://dx.doi.org/10.1136/neurintsurg-2020-016757DOI Listing
August 2021

Type A Aortic Dissection With Cerebral Malperfusion: New Insights.

Ann Thorac Surg 2021 08 27;112(2):501-509. Epub 2020 Oct 27.

Department of Cardiac Surgery, University of Michigan, Ann Arbor, Michigan.

Background: Management of type A aortic dissection with cerebral malperfusion poses a significant challenge. Although involvement of craniocervical vessels is undoubtedly critical, it is not well investigated in the surgical literature.

Methods: Between 1997 and 2019, 775 patients presented with acute type A aortic dissection and 80 (10%) with cerebral malperfusion. All patients were transferred from outside institutions. Medical records and imaging studies were retrospectively reviewed.

Results: Fifty-nine patients (74%) underwent an open repair, 2 (3%) had an endovascular aortic repair, 2 (3%) had carotid stenting, and 18 (23%) received nonoperative management. In-hospital mortality of all comers was 40.0%, and 81.3% were neurology related. Among the 45 patients (56%) in whom cerebrocervical imaging studies were available, 11 (24%) had an internal carotid artery (ICA) occlusion and 28 (62%) had a common carotid artery (CCA) occlusion without ICA involvement as the culprit lesion. Six comatose patients (55%) were in the ICA group and 10 comatose patients (36%) in the CCA group (P = .28). All patients with ICA occlusion developed cerebral edema and herniation syndrome regardless of the management and died. In contrast 79% of patients with unilateral or bilateral CCA occlusion survived to hospital discharge (P < .001), and only 3 (11%) had a neurologic death (P < .001).

Conclusions: ICA occlusion in the presence of type A aortic dissection may be a surrogate marker for dismal neurologic outcomes regardless of the surgical approach, whereas CCA occlusion or comatose state should not preclude surgical candidacy. A prompt neck computed tomography angiography may be warranted in patients with cerebral malperfusion.
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http://dx.doi.org/10.1016/j.athoracsur.2020.08.046DOI Listing
August 2021

Intra-hematomal White Matter Tracts Act As a Scaffold for Macrophage Infiltration After Intracerebral Hemorrhage.

Transl Stroke Res 2021 10 22;12(5):858-865. Epub 2020 Oct 22.

Department of Neurosurgery, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA.

Intracerebral hemorrhage (ICH) is a stroke subtype with high mortality and severe morbidity. Hemorrhages frequently develop within the white matter, but whether white matter fibers within the hematoma survive after ICH has not been well studied. The current study examines whether white matter fibers persist in the hematoma after ICH, fibers that might be impacted by evacuation, and their relationship to macrophage infiltration in a porcine model. Male piglets had 2.5 ml blood with or without CD47 blocking antibody injected into the right frontal lobe. Brains were harvested from 3 days to 2 months after ICH for brain histology. White matter fibers were detected within the hematoma 3 and 7 days after hemorrhage by brain histology and myelin basic protein immunohistochemistry. White matter still remained in the hematoma cavity at 2 months after ICH. Macrophage scavenger receptor-1 positive macrophages/microglia and heme oxygenase-1 positive cells infiltrated into the hematoma along the intra-hematomal white matter fibers at 3 and 7 days after ICH. Treatment with CD47 blocking antibody enhanced the infiltration of these cells. In conclusion, white matter fibers exist within the hematoma after ICH and macrophages/microglia may use such fibers as a scaffold to infiltrate into the hematoma and aid in hematoma clearance.
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http://dx.doi.org/10.1007/s12975-020-00870-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8060356PMC
October 2021

Endovascular Treatment of Arteriovenous Malformations of the Head and Neck: Focus on the Yakes Classification and Outcomes.

J Vasc Interv Radiol 2020 Nov 18;31(11):1810-1816. Epub 2020 Sep 18.

Department of Radiology, University of Michigan, Ann Arbor, Michigan; Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan. Electronic address:

Purpose: To evaluate endovascular treatment of head and neck arteriovenous malformations (AVMs) based on the Yakes AVM classification and correlate treatment approach with clinical and angiographic outcomes.

Materials And Methods: A retrospective single-center study was performed in patients who underwent endovascular treatment of head and neck AVMs between January 2005 and December 2017. Clinical and operative records, imaging, and postoperative courses of patients were reviewed. Clinical stage was determined according to the Schobinger classification. AVM architecture and treatment approaches were determined according to the Yakes classification. Primary outcomes were clinical and angiographic treatment success rates and complication rates, with analysis according to the Yakes classification.

Results: A total of 29 patients (15 females) were identified, with a mean age of 30.6 years. Downgrading of the Schobinger clinical classification was achieved in all patients. Lesions included 8 Yakes type IIa, 5 type IIb, 1 type IIIa and IIIb, and 14 type IV. Lesions were treated using an intra-arterial, nidal, or transvenous approach, using ethanol and liquid embolic agents. Arteriovenous shunt eradication of >90% was achieved in 22 of 28 patients (79%), including 9 of 13 (69%) of Yakes type IV lesions and 13 of 15 (87%) of the other types. There were 5 significant complications in 79 procedures (6%), including 4 of 50 (8%) in Yakes type IV lesions.

Conclusions: Schobinger stage was downgraded in all patients. Arteriovenous shunt eradication of >90% was achieved in most patients. Yakes type IV lesions required more sessions, and shunt eradication was higher in the Yakes II and III groups.
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http://dx.doi.org/10.1016/j.jvir.2020.01.036DOI Listing
November 2020

Drivers of variation in 90-day episode payments after mechanical thrombectomy for acute ischemic stroke.

J Neurointerv Surg 2021 Jun 31;13(6):519-523. Epub 2020 Jul 31.

Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA

Background: Although mechanical thrombectomy for acute ischemic stroke from a large vessel occlusion is now the standard of care, little is known about cost variations in stroke patients following thrombectomy and factors that influence these variations.

Methods: We evaluated claims data for 2016 to 2018 for thrombectomy-performing hospitals within Michigan through a registry that includes detailed episode payment information for both Medicare and privately insured patients. We aimed to analyze price-standardized and risk-adjusted 90-day episode payments in patients who underwent thrombectomy. Hospitals were grouped into three payment terciles for comparison. Statistical analysis was carried out using unpaired -test, Chi-square, and ANOVA tests.

Results: 1076 thrombectomy cases treated at 16 centers were analyzed. The average 90-day episode payment by hospital ranged from $53 046 to $81,767, with a mean of $65 357. A $20 467 difference (35.1%) existed between the high and low payment hospital terciles (P<0.0001), highlighting a significant payment variation across hospital terciles. The primary drivers of payment variation were related to post-discharge care which accounted for 38% of the payment variation (P=0.0058, inter-tercile range $11,977-$19,703) and readmissions accounting for 26% (P=0.016, inter-tercile range $3,315-$7,992). This was followed by professional payments representing 20% of the variation (P<0.0001, inter-tercile range $7525-$9,922), while index hospitalization payment was responsible for only 16% of the 90-day episode payment variation (P=0.10, inter-tercile range $35,432-$41,099).

Conclusions: There is a wide variation in 90-day episode payments for patients undergoing mechanical thrombectomy across centers. The main drivers of payment variation are related to differences in post-discharge care and readmissions.
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http://dx.doi.org/10.1136/neurintsurg-2020-016389DOI Listing
June 2021

Perihematomal brain tissue iron concentration measurement by MRI in patients with intracerebral hemorrhage.

CNS Neurosci Ther 2020 09 21;26(9):896-901. Epub 2020 May 21.

Department of Neurosurgery, 1500 E Medical Center Dr, Ann Arbor, MI, USA.

Aims: Over the past two decades, animal intracerebral hemorrhage (ICH) model studies have indicated that iron, released after hemoglobin degradation, is neurotoxic. Iron phantom and animal experiments have shown that magnetic resonance imaging (MRI) relaxivity maps correlate with iron concentration. This study expands this into patients.

Methods: Eighteen human subjects with ICH underwent MRI at 3, 14, and 30 days. R2* relaxivity maps were used to calculate perihematomal iron concentrations and T2 imaging to determine hematoma and edema volumes.

Results: Perihematomal iron concentrations were increased at all three time points and decreased with distance from the hematoma. While perihematomal iron concentrations did not vary with hematoma size, the total iron overload (increased iron concentration x volume of affected tissue) did. Total iron overload correlated with edema volume.

Conclusions: These results demonstrate the feasibility of measuring perihematomal iron in ICH patients which may be important for monitoring treatment strategies and assessing efficacy noninvasively.
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http://dx.doi.org/10.1111/cns.13395DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7415200PMC
September 2020

Treatment Strategies for Tandem Occlusions in Acute Ischemic Stroke.

Semin Intervent Radiol 2020 Jun 14;37(2):207-213. Epub 2020 May 14.

Department of Radiology, Michigan Medicine, Ann Arbor, Michigan.

There is no consensus for the treatment of a tandem occlusion (TO) in a patient presenting with an acute ischemic stroke. In this review article, we will focus on the controversial treatment strategies for TOs. First, we will discuss treatment options including retrograde, antegrade, and delayed approaches. Second, the role of carotid stent placement versus balloon angioplasty for the extracranial occlusion will be presented. Third, anticoagulation and antiplatelet regimens for the treatment TOs published in the literature will be reviewed. Finally, we will discuss whether there is a role for coil occlusion of the cervical carotid artery or whether staged carotid revascularization days after mechanical thrombectomy of the intracranial occlusion maybe appropriate. The optimal treatment strategy of TO has not been established and further larger trials need to be performed to answer the question.
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http://dx.doi.org/10.1055/s-0040-1709207DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224971PMC
June 2020

Multiphase CT Angiography for Evaluation and Diagnosis of Complex Spinal Dural Arteriovenous Fistula.

Can J Neurol Sci 2020 09 14;47(5):681-682. Epub 2020 May 14.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA.

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http://dx.doi.org/10.1017/cjn.2020.94DOI Listing
September 2020

Analysis of human emboli and thrombectomy forces in large-vessel occlusion stroke.

J Neurosurg 2020 Feb 28;134(3):893-901. Epub 2020 Feb 28.

Departments of3Neurosurgery and.

Objective: This study's purpose was to improve understanding of the forces driving the complex mechanical interaction between embolic material and current stroke thrombectomy devices by analyzing the histological composition and strength of emboli retrieved from patients and by evaluating the mechanical forces necessary for retrieval of such emboli in a middle cerebral artery (MCA) bifurcation model.

Methods: Embolus analogs (EAs) were generated and embolized under physiological pressure and flow conditions in a glass tube model of the MCA. The forces involved in EA removal using conventional endovascular techniques were described, analyzed, and categorized. Then, 16 embolic specimens were retrieved from 11 stroke patients with large-vessel occlusions, and the tensile strength and response to stress were measured with a quasi-static uniaxial tensile test using a custom-made platform. Embolus compositions were analyzed and quantified by histology.

Results: Uniaxial tension on the EAs led to deformation, elongation, thinning, fracture, and embolization. Uniaxial tensile testing of patients' emboli revealed similar soft-material behavior, including elongation under tension and differential fracture patterns. At the final fracture of the embolus (or dissociation), the amount of elongation, quantified as strain, ranged from 1.05 to 4.89 (2.41 ± 1.04 [mean ± SD]) and the embolus-generated force, quantified as stress, ranged from 63 to 2396 kPa (569 ± 695 kPa). The ultimate tensile strain of the emboli increased with a higher platelet percentage, and the ultimate tensile stress increased with a higher fibrin percentage and decreased with a higher red blood cell percentage.

Conclusions: Current thrombectomy devices remove emboli mostly by applying linear tensile forces, under which emboli elongate until dissociation. Embolus resistance to dissociation is determined by embolus strength, which significantly correlates with composition and varies within and among patients and within the same thrombus. The dynamic intravascular weakening of emboli during removal may lead to iatrogenic embolization.
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http://dx.doi.org/10.3171/2019.12.JNS192187DOI Listing
February 2020

Fluorescein angiography findings in both eyes of a unilateral retinoblastoma case during intra-arterial chemotherapy with melphalan.

Int J Ophthalmol 2019 18;12(12):1987-1989. Epub 2019 Dec 18.

Department of Ophthalmology and Visual Sciences, W.K. Kellogg Eye Center, MI 48105, USA.

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http://dx.doi.org/10.18240/ijo.2019.12.24DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6901897PMC
December 2019

A combination of Deferoxamine mesylate and minimally invasive surgery with hematoma lysis for evacuation of intracerebral hemorrhage.

J Cereb Blood Flow Metab 2020 02 2;40(2):456-458. Epub 2019 Dec 2.

Department of Neurological Surgery, University of Michigan, Ann Arbor, USA.

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http://dx.doi.org/10.1177/0271678X19892660DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7370622PMC
February 2020

Single Step Blending of PEDOT:PSS/SPGO Nanocomposite via Low Temperature Solid Phase Addition of Graphene Oxide for Effective Hole Transport Layer in Organic Solar Cells.

J Nanosci Nanotechnol 2020 Jun;20(6):3888-3895

Nanoscience and Nanotechnology Centre, Department of Chemistry, Kumaun University, Nainital 263001, Uttarakhand, India.

Herein, we report the modification of PEDOT:PSS by direct addition of graphene oxide powder processed by spray dryer (SPGO) for the enhancement in the performance of organic solar cell. The preparation of PEDOT:PSS/SPGO composite was done by direct incorporation of graphene oxide powder at lower temperature i.e., below 5 °C. Raman spectroscopy of the prepared PEDOT:PSS/SPGO nanocomposites at low temperature suggested that low temperature plays a vital role to improve the ability of these composite as hole transport layer by improving adhesive properties of the composite. Atomic force microscopy (AFM) analysis suggested that the adhesive ability of these composite decreased surface roughness and thus providing smoother path for the hole transportation. After the successful synthesis of PEDOT:PSS/SPGO nanocomposites, ITO/PEDOT:PSS/SPGO/PTB7:PC71BM/Al based organic solar cell was fabricated. The curves under AM 1.5G illumination (100 mW/cm²) of the PTB7:PCBM based OSCs using PEDOT:PSS/SPGO as a HTL exhibit = 0.67 V, = 17.3 mA, FF = 41.5%, PCE = 4.82%, and device with PEDOT:PSS as HTL exhibit = 0.68 V, = 16.0 mA/cm², FF = 38.7% and PCE = 4.04%. The enhance PCE in case of PEDOT:PSS/SPGO based devices depicted that the direct inclusion of graphene oxide in PEDOT:PSS increased the PCE almost 16%, which arises due the high conductivity and stable pi-pi stacking of the spray dryer processed graphene sheets with PEDOT:PSS which ease the charge carrier mobility, thus providing feasible path for charge transportation.
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http://dx.doi.org/10.1166/jnn.2020.17532DOI Listing
June 2020

Hemorrhagic stroke-Pathomechanisms of injury and therapeutic options.

CNS Neurosci Ther 2019 10;25(10):1073-1074

Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan.

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http://dx.doi.org/10.1111/cns.13225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6776738PMC
October 2019

Clinical and experimental aspects of aneurysmal subarachnoid hemorrhage.

CNS Neurosci Ther 2019 10;25(10):1096-1112

Department of Neurological Surgery, University of Michigan, Ann Arbor, Michigan.

Aneurysmal subarachnoid hemorrhage (aSAH) continues to be associated with significant morbidity and mortality despite advances in care and aneurysm treatment strategies. Cerebral vasospasm continues to be a major source of clinical worsening in patients. We intended to review the clinical and experimental aspects of aSAH and identify strategies that are being evaluated for the treatment of vasospasm. A literature review on aSAH and cerebral vasospasm was performed. Available treatments for aSAH continue to expand as research continues to identify new therapeutic targets. Oral nimodipine is the primary medication used in practice given its neuroprotective properties. Transluminal balloon angioplasty is widely utilized in patients with symptomatic vasospasm and ischemia. Prophylactic "triple-H" therapy, clazosentan, and intraarterial papaverine have fallen out of practice. Trials have not shown strong evidence supporting magnesium or statins. Other calcium channel blockers, milrinone, tirilazad, fasudil, cilostazol, albumin, eicosapentaenoic acid, erythropoietin, corticosteroids, minocycline, deferoxamine, intrathecal thrombolytics, need to be further investigated. Many of the current experimental drugs may have significant roles in the treatment algorithm, and further clinical trials are needed. There is growing evidence supporting that early brain injury in aSAH may lead to significant morbidity and mortality, and this needs to be explored further.
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http://dx.doi.org/10.1111/cns.13222DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6776745PMC
October 2019

Copper Bromide as an Efficient Solution-Processable Hole Transport Layer for Organic Solar Cells: Effect of Solvents.

ACS Omega 2019 Mar 29;4(3):6028-6034. Epub 2019 Mar 29.

Photovoltaic Metrology Section, Advanced Materials & Device Metrology Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012, India.

In this work, we report copper bromide (CuBr) as an efficient, inexpensive, and solution-processable hole transport layer (HTL) for organic solar cells (OSCs) for the first time. To examine the effectiveness of the material in general, three different solvents such as acetonitrile (MeCN), dimethyl sulfoxide (DMSO), and dimethylformamide (DMF) are used for solution-processing thin-film deposition of CuBr. CuBr thin films deposited from different solvents show high transparency and no significant difference has been observed in absorption in the visible and near-IR range, whereas a slight difference has been found in the near-UV range by changing the solvents. Furthermore, two most studied combinations of the active layer such as PTB7/PCBM and PCDTBT:/PCBM are used for device fabrication with geometry of ITO/CuBr(HTL) active layer/Al. By using CuBr as a HTL in OSCs, the power conversion efficiencies (PCEs) have been achieved to up to 5.16 and 4.72% with PTB7/PCBM and PCDTBT/PCBM active layers, respectively. The CuBr film from DMF solvent shows highest PCE as compared to films deposited from DMSO and MeCN solvents. Different solvents used for HTL deposition have a major effect on the fill factor (FF), while very little difference on open circuit voltage ( ) and short circuit current ( ) has been observed. It may be mentioned here that a small difference of device parameters (PCE, FF, , and ) has been observed in the devices using the HTL deposited from DMF and DMSO solvents, whereas a significant difference of the device parameters has been found in devices using the HTL from MeCN solvent.
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http://dx.doi.org/10.1021/acsomega.8b03038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648316PMC
March 2019

Neuroprotection for ischemic stroke in the endovascular era: A brief report on the future of intra-arterial therapy.

J Clin Neurosci 2019 Nov 17;69:289-291. Epub 2019 Aug 17.

Department of Neurosurgery, University of Michigan, Ann Arbor, MI, United States. Electronic address:

Mechanical thrombectomy is now at the forefront of the treatment of large vessel acute ischemic stroke (AIS). Selective intra-arterial (IA) access has opened a new avenue for neuroprotection in AIS that has the potential to maximize local benefit while minimizing systemic effects. On a cellular level, neuroprotective strategies are aimed at reducing inflammation and free-radical formation, maintaining blood-brain barrier fidelity, and preventing cellular death. Strategies under investigation include IA infusion of neuroprotective agents, IA administration of stem cells, and selective IA hypothermia. In this technical report, we briefly discuss pathologic mechanisms in AIS and highlight potential neuroprotective strategies that are administered selectively via the IA route.
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http://dx.doi.org/10.1016/j.jocn.2019.08.001DOI Listing
November 2019

Computed Tomography Myelosimulation Versus Magnetic Resonance Imaging Registration to Delineate the Spinal Cord During Spine Stereotactic Radiosurgery.

World Neurosurg 2019 02 26;122:e655-e666. Epub 2018 Oct 26.

Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan, USA.

Background: Underestimation of the spinal cord's volume or position during spine stereotactic radiosurgery can lead to severe myelopathy, whereas overestimation can lead to tumor underdosage. Spinal cord delineation is commonly achieved by registering a magnetic resonance imaging (MRI) study with a computed tomography (CT) simulation scan or by performing myelography during CT simulation (myelosim). We compared treatment planning outcomes for these 2 techniques.

Methods: Twenty-three cases of spine stereotactic radiosurgery were analyzed that had both a myelosim and corresponding MRI study for registration. The spinal cord was contoured on both imaging data sets by 2 independent blinded physicians, and Dice similarity coefficients were calculated to compare their spatial overlap. Two treatment plans (16 Gy and 18 Gy) were created using the MRI and CT contours (92 plans total). Dosimetric parameters were extracted and compared by modality to assess tumor coverage and spinal cord dose.

Results: No differences were found in the partial spinal cord volumes contoured on MRI versus myelosim (4.71 ± 1.09 vs. 4.55 ± 1.03 cm; P = 0.34) despite imperfect spatial agreement (mean Dice similarity coefficient, 0.68 ± 0.05). When the registered MRI contours were used for treatment planning, significantly worse tumor coverage and greater spinal cord doses were found compared with myelosim planning. For the 18-Gy plans, 10 of 23 MRI cases (43%) exceeded the spinal cord or cauda dose constraints when using myelosim as the reference standard.

Conclusions: Significant spatial, rather than volumetric, differences were found between the MRI- and myelosim-defined spinal cord structures. Tumor coverage was compromised with MRI-based planning, and the high spinal cord doses were a concern. Future work is necessary to compare thin-cut, volumetric MRI registration or MRI simulation with myelosim.
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http://dx.doi.org/10.1016/j.wneu.2018.10.118DOI Listing
February 2019
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