1
|
Prather KY, Ozaydin B, Peters M, Tally E, Zieles K, Omini ME, Gernsback JE, Desai VR, Balsara KE, Jea A. Pediatric neurosurgery through the lens of time-driven activity-based costing: a pilot study. J Neurosurg Pediatr 2024; 33:436-443. [PMID: 38335524 DOI: 10.3171/2023.12.peds23267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 12/05/2023] [Indexed: 02/12/2024]
Abstract
OBJECTIVE Time-driven activity-based costing (TDABC) is a method used in cost accounting that has gained traction in health economics to identify value optimization initiatives. It measures time, assigns value to time increments spent on a patient, and integrates the cost of material and human resources utilized in each episode of care. In this study, the authors report the first use of TDABC to evaluate costs in a pediatric neurosurgical practice. METHODS A clinical pathway was developed with a multifunction team. A time survey among each care team member, including surgeons, medical assistants (MAs), and patient service representatives (PSRs), was carried out prospectively over a 10-week period at a pediatric neurosurgery clinic. Consecutive patient encounters for Chiari malformation (CM), hydrocephalus, or tethered cord syndrome (TCS) were included. Encounters were categorized as new or established. Relative annual personnel costs, using the salary of a PSR as a reference (i.e., 1.0-unit cost), were calculated for all members using departmental financial data after adjustments. The relative capacity cost rates (minute-1) for each personnel, a representation of per capita cost per minute, were then derived, and the relative costs per visit were calculated. RESULTS A total of 110 visits (24 new, 86 established) were captured, including 40% CM, 41% hydrocephalus, and 19% TCS encounters. Surgeons had the highest relative capacity cost rate (118.4 × 10-6), more than 10-fold higher than that of an MA or PSR (10.65 × 10-6 and 9.259 × 10-6, respectively). Surgeons also logged more time with patients compared with the rest of the care team in nearly all visits (p ≤ 0.002); consequently, the total visit costs were primarily driven by the surgeon cost (p < 0.0001). Overall, surgeon cost constituted the vast majority of the total visit cost (92%-93%), regardless of whether the visits were new or established. Visit costs did not differ by diagnosis. On average, new visits took longer than established visits (p < 0.001). This difference was largely driven by new CM visits (44.3 ± 13.7 minutes), which were significantly longer than established CM visits (29.8 ± 9.2 minutes; p = 0.001). CONCLUSIONS TDABC may reveal opportunities to maximize value by highlighting instances of variability and high cost in each module of care delivery. Physician leaders in pediatric neurosurgery may be able to use this information to allocate costs and streamline value care pathways.
Collapse
|
2
|
Prather KY, Baier MP, Coulibaly NJ, Stephens ME, Chen S, Omini ME, Jea A. Resection of intradural spinal lesions with concomitant instrumented fusion in children: a systematic review and representative cases. J Neurosurg Pediatr 2024:1-12. [PMID: 38579345 DOI: 10.3171/2024.1.peds23444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/29/2024] [Indexed: 04/07/2024]
Abstract
OBJECTIVE More than one-third of pediatric patients who undergo resection of intradural spine lesions develop progressive postoperative deformity, with as many as half of these patients subsequently requiring surgical fusion. Intradural spinal procedures with simultaneous instrumented fusion in children, however, are infrequently performed. Moreover, the rationale for patient selection, outcomes, and safety of this single-stage surgery in children has not been systematically investigated. In this study, the authors review the practice of simultaneous intradural spinal resection and instrumented fusion in pediatric patients and provide two representative case examples from their institution. METHODS The authors searched the PubMed and Embase databases and performed a systematic review following the PRISMA protocol. Original articles of pediatric patients (age ≤ 18 years) who underwent intradural spine surgery, regardless of pathology, with concomitant instrumented fusion and reported outcomes were included. An institutional database of all spinal operations with instrumented fusion performed in patients aged ≤ 18 years over a 3-year period was screened to identify those who underwent intradural spine surgery with concomitant fusion. RESULTS Nine patients (median age 12 years) from 6 studies who underwent intradural lesion resection and concomitant fusion met inclusion criteria. Among all 11 patients included, primary rationales for concomitant fusion were extensive bone removal (i.e., corpectomy or total facetectomy, 73%), concerns for deformity in the setting of multilevel laminectomy/laminoplasty (18%), and severe baseline deformity (9%). The most represented pathology was neurenteric cyst (55%) followed by schwannoma (18%). Myxopapillary ependymoma, granular cell tumor, and pilocytic astrocytoma each were seen in 1 case. Seven patients (64%) underwent an anterior-approach corpectomy, tumor resection, and fusion, while the remaining 4 patients (36%) underwent a posterior approach. All patients with at least 1 year of follow-up cases achieved bony fusion. CSF leak and new-onset neurological deficit each occurred in 9% (1/11). CONCLUSIONS The rationales for performing single-stage intradural resection and fusion in pediatric patients in studies to date include the presence of severe baseline deformity, large extent of bone resection, and multilevel laminectomy/laminoplasty across cervicothoracic or thoracolumbar junctions. As current literature involving this cohort is limited, more data are needed to determine when concomitant fusion in intradural resections is appropriate in pediatric patients and whether its routine implementation is safe or beneficial.
Collapse
Affiliation(s)
- Kiana Y Prather
- 1Section of Pediatric Neurosurgery, Oklahoma Children's Hospital, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City; and
| | - Matthew P Baier
- 1Section of Pediatric Neurosurgery, Oklahoma Children's Hospital, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City; and
| | - Nangorgo J Coulibaly
- 1Section of Pediatric Neurosurgery, Oklahoma Children's Hospital, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City; and
| | - Mark E Stephens
- 1Section of Pediatric Neurosurgery, Oklahoma Children's Hospital, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City; and
| | - Sixia Chen
- 2Department of Biostatistics and Epidemiology, Hudson College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Michael E Omini
- 1Section of Pediatric Neurosurgery, Oklahoma Children's Hospital, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City; and
| | - Andrew Jea
- 1Section of Pediatric Neurosurgery, Oklahoma Children's Hospital, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City; and
| |
Collapse
|
3
|
Evans AR, Prather KY, Battiste J, Fung KM, Dunn IF, Graffeo CS. Genetically Distinct Oligosarcoma Arising from Oligodendroglioma: Systematic Review & Illustrative Case Example. World Neurosurg 2024:S1878-8750(24)00403-0. [PMID: 38490447 DOI: 10.1016/j.wneu.2024.03.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 03/06/2024] [Indexed: 03/17/2024]
Abstract
BACKGROUND Oligosarcoma is a rare central nervous system (CNS) neoplasm that may arise following oligodendroglioma resection, which demonstrates a unique genetic profile and aggressive clinical phenotype. We present a systematic review and illustrative case example emphasizing the clinical and prognostic features of this unusual and unfavorable neuro-oncologic disease. METHODS Systematic literature review and illustrative case report. RESULTS A 41-year-old man who had undergone 2 neurosurgical resections for a World Health Organization grade II oligodendroglioma (Ki-67 = 5-10%, 1p/19q codeleted, IDH2 mutated), without adjuvant chemoradiation, presented with seizures seven years after resection. An extra-axial mass was identified adjacent to the resection cavity, in which gross total resection was achieved. Pathology confirmed World Health Organization grade IV oligosarcoma (Ki-67 = 20%). Adjuvant chemoradiation was initiated, with disease control observed over 6 months of follow-up. Seven publications met inclusion criteria. Oligosarcoma has been confirmed in 36 lesions, arising in 35 patients; 5 were primary oligosarcoma, while 31 occurred in the setting of prior resected oligodendroglioma or oligoastrocytoma. Features shared by these lesions include regain of H3K27me3 expression, 1p/19q codeletion, homozygous deletion of CDKN2A/B, loss of 6q, loss of NF1 and YAP1, and attenuation of CpG island methylator. Median survival after oligosarcoma diagnosis was 1.3 years (range, 0-5.2; n = 35). CONCLUSIONS Oligosarcoma is a prognostically unfavorable CNS neoplasm with characteristic imaging and pathologic features, and a strong association with previously resected oligodendroglioma. Aggressive treatment is recommended, including gross total resection and adjuvant chemoradiation. Further study is required to define optimal treatment protocol for this CNS malignancy.
Collapse
Affiliation(s)
- Alexander R Evans
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, Oklahoma
| | - Kiana Y Prather
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, Oklahoma
| | - James Battiste
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, Oklahoma
| | - Kar-Ming Fung
- Department of Pathology, University of Oklahoma, Oklahoma City, Oklahoma
| | - Ian F Dunn
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, Oklahoma
| | | |
Collapse
|
4
|
Prather KY, Hopkins NJ, Zhao X, Desai VR. Aspirator-Assisted Endoscopic Third Ventriculostomy in an Infant: 2-Dimensional Operative Video. World Neurosurg 2023; 180:36. [PMID: 37689360 DOI: 10.1016/j.wneu.2023.08.140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 08/29/2023] [Accepted: 08/31/2023] [Indexed: 09/11/2023]
Abstract
Endoscopic third ventriculostomy (ETV) is an effective treatment for hydrocephalus in carefully selected patients.1 Studies have shown that larger ostomy size may be associated with higher ETV success and reduced ostomy closure in pediatric and adult patients.2-5 Therefore dilation of the ostomy is a key step in this procedure, which is traditionally accomplished with a balloon catheter, leaving behind loose redundant tissue at the ostomy site. In this 2-dimensional endoscopic operation (Video 1), we demonstrate the technique of using an aspiration device to enlarge the ETV ostomy in a controlled and efficient manner while eliminating redundant tissue. The patient is a 6-month-old girl with newly developed triventricular hydrocephalus seen on head ultrasound, manifested as upward gaze palsy, fontanelle fullness, and rapidly increasing head circumference. We chose to treat her with an ETV, given an ETV success score of 70.6,7 She underwent an ETV augmented with the NICO Myriad aspirator (NICO Corporation, Indianapolis, Indiana, USA) and achieved excellent clinical outcome. No intraoperative or postoperative complication occurred. Postoperative magnetic resonance imaging demonstrated an 8.4-mm ostomy on the third ventricular floor, nearly twice the size of a typical ETV ostomy.5 The key considerations in using this device include setting a low aspiration limit to avoid oversuction and using only mediolateral motion to avoid damage to the basilar artery. Future comparative studies are needed to investigate the efficacy, safety, and long-term outcome in aspirator-assisted ETV versus traditional techniques, as well as to evaluate ostomy size as an independent variable for long-term ETV success.
Collapse
Affiliation(s)
- Kiana Y Prather
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Nicholas J Hopkins
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Xiaochun Zhao
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Virendra R Desai
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
| |
Collapse
|
5
|
Pelargos PE, Hasanjee A, Lee B, Grossen A, Prather KY, Zhao X, Ohene-Nyako P, Baier MP, McDaniel AK, McKinney KA, Graffeo CS, Rassi EE, Dunn IF. An institutional experience in applying quality improvement measures to pituitary surgery: clinical and resource implications. Neurosurg Focus 2023; 55:E10. [PMID: 38039538 PMCID: PMC10798057 DOI: 10.3171/2023.9.focus23545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 09/28/2023] [Indexed: 12/03/2023]
Abstract
OBJECTIVE The aim of this study was to report the authors' experience developing a Lean Six Sigma clinical care pathway (CCP) for endoscopic endonasal transsphenoidal operations. METHODS Using Lean Six Sigma quality improvement principles-including the define, measure, analyze, improve, and control framework-the authors developed a CCP for endoscopic endonasal transsphenoidal operations, incorporating preoperative, intraoperative, and inpatient and outpatient postoperative phases of care. Efficacy and quality metrics were defined as postoperative length of stay (LOS), presentation to the emergency department (ED) or readmission within 30 days of discharge, and hospital charges. The study included all adult patients who underwent elective endoscopic endonasal resection for pituitary adenoma, Rathke's cleft cyst, craniopharyngioma, pituicytoma, or arachnoid cyst during the sampling period (April 1, 2018, to December 31, 2022). RESULTS Two hundred twenty-eight patients met criteria and were included; 94 were treated before and 134 were treated after implementation of the CCP. Differences between groups in age, gender, race, BMI, American Society of Anesthesiologists classification, geographic distribution, preoperative serum sodium, tumor size, adenoma functional status, and prior surgery were not significant. The mean postoperative LOS significantly decreased from 4.5 to 1.7 days following CCP implementation (p < 0.0001); LOS variability also decreased, with the standard deviation declining from 3.1 to 1.5 days. The proportion of patients discharged on postoperative day (POD) 1 significantly increased from 0% to 61.9% (p < 0.0001). Fewer than one-quarter of the patients (23.4%) were discharged by POD 2 prior to the CCP, while 88.8% of were discharged by POD 2 after CCP implementation (p < 0.0001). Rates of 30-day ED presentations or readmissions were not significantly different (2.1% vs 6.0%, p = 0.20, and 7.5% vs 6.7%, p > 0.99, respectively). Mean per-patient hospital costs declined from $38,326 to $26,289 (p < 0.0001), with an associated change in cost variability from a standard deviation of $16,716 to $12,498. CONCLUSIONS CCP implementation significantly improved LOS and costs of endoscopic endonasal resection, without adversely impacting postoperative ED presentations or readmissions.
Collapse
Affiliation(s)
- Panayiotis E. Pelargos
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Aamr Hasanjee
- Department of Otolaryngology–Head and Neck Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Benjamin Lee
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Audrey Grossen
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Kiana Y. Prather
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Xiaochun Zhao
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Prince Ohene-Nyako
- Department of Otolaryngology–Head and Neck Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Matthew P. Baier
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Amanda Kate McDaniel
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Kibwei A. McKinney
- Department of Otolaryngology–Head and Neck Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Christopher S. Graffeo
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Edward El Rassi
- Department of Otolaryngology–Head and Neck Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Ian F. Dunn
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| |
Collapse
|
6
|
Zhao X, Prather KY, Tavakol SA, Gernsback JE. Bilateral cerebellopontine angle lipomas in an infant with encephalocele: illustrative case. J Neurosurg Case Lessons 2023; 6:CASE23315. [PMID: 37773761 PMCID: PMC10555580 DOI: 10.3171/case23315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/15/2023] [Indexed: 10/01/2023]
Abstract
BACKGROUND Bilateral cerebellopontine angle (CPA) lipomas are extremely rare. Herein the authors present a case of bilateral CPA lipomas in an infant along with a literature review of bilateral CPA lipomas. OBSERVATIONS A newborn girl was incidentally found to have bilateral CPA lipomas during the workup for an occipital encephalocele. The encephalocele was repaired primarily on day 2 after birth. The patient demonstrated no symptoms associated with the bilateral CPA lipomas. Eight cases of bilateral CPA lipomas were identified in the literature review and are summarized. Conservative management is the consensus strategy, given minimum growth of the tumor and the high risk of surgical intervention. LESSONS This is the first reported case of bilateral CPA lipomas in an infant as well as the first with a coexisting intracranial malformation. Intracranial lipomas share an extremely low growth rate and typically do not cause severe symptoms. The management of asymptomatic or mildly symptomatic bilateral CPA lipomas is usually conservative.
Collapse
|
7
|
Powell SM, Wang B, Herrera VE, Prather KY, Nguyen NT, Abucayon EG, Thomas LM, Safo MK, Richter-Addo GB. Crystal structural investigations of heme protein derivatives resulting from reactions of aryl- and alkylhydroxylamines with human hemoglobin. J Inorg Biochem 2023; 246:112304. [PMID: 37406385 PMCID: PMC10348690 DOI: 10.1016/j.jinorgbio.2023.112304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 06/10/2023] [Accepted: 06/22/2023] [Indexed: 07/07/2023]
Abstract
Phenylhydroxylamine (PhNHOH) and nitrosobenzene (PhNO) interact with human tetrameric hemoglobin (Hb) to form the nitrosobenzene adduct Hb(PhNO). These interactions also frequently lead to methemoglobin formation in red blood cells. We utilize UV-vis spectroscopy and X-ray crystallography to identify the primary and secondary products that form when PhNHOH and related alkylhydroxylamines (RNHOH; R = Me, t-Bu) react with human ferric Hb. We show that with MeNHOH, the primary product is Hb[α-FeIII(H2O)][β-FeII(MeNO)], in which nitrosomethane is bound to the β subunit but not the α subunit. Attempts to isolate a nitrosochloramphenicol (CAMNO) adduct resulted in our isolation of a Hb[α-FeII][β-FeII-cySOx]{CAMNO} product (cySOx = oxidized cysteine) in which CAMNO was located outside of the protein in the solvent region between the β2 and α2 subunits of the same tetramer. We also observed that the βcys93 residue had been oxidized. In the case of t-BuNHOH, we demonstrate that the isolated product is the β-hemichrome Hb[α-FeIII(H2O)][β-FeIII(His)2]{t-BuNHOH}, in which the β heme has slipped ∼4.4 Å towards the solvent exterior to accommodate the bis-His heme coordination. When PhNHOH is used, a similar β-hemichrome Hb[α-FeIII(H2O)][β-FeIII(His)2-cySOx]{PhNHOH} was obtained. Our results reveal, for the first time, the X-ray structural determination of a β-hemichrome in a human Hb derivative. Our UV-vis and X-ray crystal structural result reveal that although Hb(PhNO) and Hb(RNO) complexes may form as primary products, attempted isolation of these products by crystallization may result in the structural determination of their secondary products which may contain β-hemichromes en route to further protein degradation.
Collapse
Affiliation(s)
- Samantha M Powell
- Price Family Foundation Institute of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA; Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Bing Wang
- Price Family Foundation Institute of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Viridiana E Herrera
- Price Family Foundation Institute of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA; Department of Chemistry and Physics, Ivory V. Nelson Science Center, Lincoln University, Lincoln University, PA, 19352, USA
| | - Kiana Y Prather
- Price Family Foundation Institute of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA; University of Oklahoma College of Medicine, 800 Stanton L. Young Blvd, Oklahoma City, OK 73117, USA
| | - Nancy T Nguyen
- Price Family Foundation Institute of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA; University of Oklahoma College of Medicine, 800 Stanton L. Young Blvd, Oklahoma City, OK 73117, USA
| | - Erwin G Abucayon
- Price Family Foundation Institute of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Leonard M Thomas
- Price Family Foundation Institute of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Martin K Safo
- Department of Medicinal Chemistry, School of Pharmacy and Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, 800 East Leigh Street, Richmond, VA 23219, USA
| | - George B Richter-Addo
- Price Family Foundation Institute of Structural Biology, Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA.
| |
Collapse
|
8
|
Gonce CE, Prather KY, Bauer AM, Shakir HJ, Jen SS, Graffeo CS. Ruptured vertebrobasilar junction aneurysm supplied by reversed flow from the anterior spinal artery: Illustrative case report. Interv Neuroradiol 2023:15910199231194664. [PMID: 37593792 DOI: 10.1177/15910199231194664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023] Open
Abstract
BACKGROUND AND IMPORTANCE In patients with vertebral artery (VA) occlusion, spontaneous flow reversal may occur in the anterior spinal artery (ASA) as a source of compensatory supply to the posterior circulation. Turbulent flow and increased flux through these small arteries may predispose to luminal damage and intracranial aneurysm formation. We report a novel case of a ruptured ASA-VA junction aneurysm in a patient with chronic bilateral VA occlusion, successfully treated with endovascular embolization. CLINICAL PRESENTATION A 62-year-old female with uncontrolled hypertension presented with acute-onset headache, emesis, neck stiffness, and decreased level of consciousness. Head computed tomography demonstrated diffuse cisternal subarachnoid hemorrhage with intraventricular extension and ventriculomegaly. Computed tomography angiography showed left VA atresia and chronic right VA occlusion just distal to the posterior inferior cerebellar artery origin, as well as a complex, bilobed aneurysm at the ASA-VA junction. Angiography demonstrated flow reversal from the ASA into the distal stump of the occluded right VA, which in turn filled the aneurysm. Of note, the patient's posterior circulation was predominantly supplied by the dilated ASA, and associated collaterals from ASA and right VA stump. The aneurysm was accessed and embolized using superselective microcatheterization over a soft microguidewire through the right cervical VA perforators supplying retrograde flow into and through the ASA. CONCLUSION ASA-VA aneurysms are exceedingly rare, and generally associated with atypical flow dynamics. Dynamic treatment strategies may be needed, especially in the setting of subarachnoid hemorrhage.
Collapse
Affiliation(s)
- Collin E Gonce
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, OK, USA
| | - Kiana Y Prather
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, OK, USA
| | - Andrew M Bauer
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, OK, USA
| | - Hakeem J Shakir
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, OK, USA
| | - Shyian S Jen
- Department of Neurosurgery, University of Oklahoma, Oklahoma City, OK, USA
| | | |
Collapse
|
9
|
Powell SM, Prather KY, Nguyen N, Thomas LM, Richter-Addo GB. Interactions of metronidazole and chloramphenicol with myoglobin: Crystal structure of a Mb-acetamide product. J PORPHYR PHTHALOCYA 2023; 27:1142-1147. [PMID: 37868702 PMCID: PMC10588810 DOI: 10.1142/s1088424623500700] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Nitroorganics present a general concern for a safe environment due to their health hazards. However, some nitroorganics such as metronidazole (Mtz) and chloramphenicol (CAM) also possess medicinal value. Mtz and CAM can undergo reductive bioactivation presumably via their nitroso derivatives. We show, using UV-vis spectroscopy, that sperm whale myoglobin (swMb) and its distal pocket mutants retaining H-bonding capacity react with Mtz in the presence of dithionite to generate products with spectra suggestive of the Fe-bound nitroso (Fe-RNO; λmax ~420 nm) forms. We have crystallized and solved the X-ray crystal structure of an H64Q swMb-acetamide compound to 1.76 Å resolution; formation of this compound results from the serendipitous crystallographic trapping, by the heme center, of acetamide from the reductive decomposition of Mtz. Only one of the swMb proteins, namely H64Q swMb with a relatively flexible Gln64 residue, reacted with CAM presumably due to the bulky nature of CAM that generally may restrict its access to the heme site.
Collapse
Affiliation(s)
- Samantha M. Powell
- Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, and Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, U.S.A. 73019
- Biological Sciences Division, Pacific Northwest National Laboratory, 902 Batelle Blvd, Richland, WA, U.S.A. 99352
| | - Kiana Y. Prather
- Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, and Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, U.S.A. 73019
- University of Oklahoma College of Medicine, 800 Stanton L. Young Blvd, Oklahoma City, OK 73117
| | - Nancy Nguyen
- Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, and Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, U.S.A. 73019
- University of Oklahoma College of Medicine, 800 Stanton L. Young Blvd, Oklahoma City, OK 73117
| | - Leonard M. Thomas
- Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, and Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, U.S.A. 73019
| | - George B. Richter-Addo
- Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, and Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, U.S.A. 73019
| |
Collapse
|
10
|
Herrera VE, Charles TP, Scott TG, Prather KY, Nguyen NT, Sohl CD, Thomas LM, Richter-Addo GB. Insights into Nitrosoalkane Binding to Myoglobin Provided by Crystallography of Wild-Type and Distal Pocket Mutant Derivatives. Biochemistry 2023; 62:1406-1419. [PMID: 37011611 DOI: 10.1021/acs.biochem.2c00725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
Abstract
Nitrosoalkanes (R-N═O; R = alkyl) are biological intermediates that form from the oxidative metabolism of various amine (RNH2) drugs or from the reduction of nitroorganics (RNO2). RNO compounds bind to and inhibit various heme proteins. However, structural information on the resulting Fe-RNO moieties remains limited. We report the preparation of ferrous wild-type and H64A sw MbII-RNO derivatives (λmax 424 nm; R = Me, Et, Pr, iPr) from the reactions of MbIII-H2O with dithionite and nitroalkanes. The apparent extent of formation of the wt Mb derivatives followed the order MeNO > EtNO > PrNO > iPrNO, whereas the order was the opposite for the H64A derivatives. Ferricyanide oxidation of the MbII-RNO derivatives resulted in the formation of the ferric MbIII-H2O precursors with loss of the RNO ligands. X-ray crystal structures of the wt MbII-RNO derivatives at 1.76-2.0 Å resoln. revealed N-binding of RNO to Fe and the presence of H-bonding interactions between the nitroso O-atoms and distal pocket His64. The nitroso O-atoms pointed in the general direction of the protein exterior, and the hydrophobic R groups pointed toward the protein interior. X-ray crystal structures for the H64A mutant derivatives were determined at 1.74-1.80 Å resoln. An analysis of the distal pocket amino acid surface landscape provided an explanation for the differences in ligand orientations adopted by the EtNO and PrNO ligands in their wt and H64A structures. Our results provide a good baseline for the structural analysis of RNO binding to heme proteins possessing small distal pockets.
Collapse
Affiliation(s)
- Viridiana E Herrera
- Department of Chemistry and Physics, Ivory V. Nelson Science Center, Lincoln University, Lincoln University, Pennsylvania 19352, United States
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 422 Curie Blvd, Philadelphia, Pennsylvania 19104, United States
- Price Family Foundation Institute of Structural Biology and Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Tatyana P Charles
- Department of Chemistry and Physics, Ivory V. Nelson Science Center, Lincoln University, Lincoln University, Pennsylvania 19352, United States
| | - Tiala G Scott
- Department of Chemistry and Physics, Ivory V. Nelson Science Center, Lincoln University, Lincoln University, Pennsylvania 19352, United States
| | - Kiana Y Prather
- Price Family Foundation Institute of Structural Biology and Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
- University of Oklahoma College of Medicine, 800 Stanton L. Young Blvd, Oklahoma City, Oklahoma 73117, United States
| | - Nancy T Nguyen
- Price Family Foundation Institute of Structural Biology and Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
- University of Oklahoma College of Medicine, 800 Stanton L. Young Blvd, Oklahoma City, Oklahoma 73117, United States
| | - Christal D Sohl
- Price Family Foundation Institute of Structural Biology and Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, United States
| | - Leonard M Thomas
- Price Family Foundation Institute of Structural Biology and Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - George B Richter-Addo
- Price Family Foundation Institute of Structural Biology and Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| |
Collapse
|
11
|
Prather KY, Shi HH, McKinney KA, Dunn IF. Chronic cerebrospinal fluid rhinorrhea as an initial presentation of chordoma: illustrative case. J Neurosurg Case Lessons 2023; 5:CASE2347. [PMID: 37014007 PMCID: PMC10555546 DOI: 10.3171/case2347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 02/20/2023] [Indexed: 04/05/2023]
Abstract
BACKGROUND Skull base chordomas are typically extradural and present with cranial nerve deficits, headache, and visual disturbances. Clival chordoma involving the dura and presenting as a spontaneous cerebrospinal fluid (CSF) leak is extremely rare and can be mistaken for other skull base lesions. Here the authors present a case of chordoma with an unusual presentation. OBSERVATIONS A 43-year-old female who presented with clear nasal drainage was diagnosed with CSF rhinorrhea secondary to a clival defect previously thought to be ecchordosis physaliphora. The patient subsequently developed bacterial meningitis and underwent endoscopic, endonasal, transclival gross-total resection of the lesion with repair of the dural defect. Pathology revealed brachyury-positive chordoma. She received adjuvant proton beam radiotherapy and has remained stable for 2 years. LESSONS Spontaneous CSF rhinorrhea can occur as a rare primary presentation of clival chordoma, requiring careful radiological interpretation and a high index of suspicion for diagnosis. Chordoma cannot be reliably differentiated from benign notochordal lesions based on imaging alone; thus, intraoperative exploration and immunohistochemistry play key roles. Clival lesions presenting with CSF rhinorrhea should undergo prompt resection to facilitate diagnosis and prevent complications. Future studies on connections between chordoma and benign notochordal lesions may help to establish management guidelines.
Collapse
Affiliation(s)
- Kiana Y. Prather
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; and
| | - Helen H. Shi
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; and
| | - Kibwei A. McKinney
- Department of Otolaryngology–Head and Neck Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Ian F. Dunn
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; and
| |
Collapse
|
12
|
Evans AR, Grossen AA, Prather KY, Conner AK. Subsuperficial Pectoralis Fascial Placement of Implantable Pulse Generators in Deep Brain Stimulation Surgery: Technical Note. Neurosurgery Open 2023. [DOI: 10.1227/neuprac.0000000000000032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
|
13
|
Westrup AM, Prather KY, Zhao X, Stephens ME, Jea AH. Transfer of extensor carpi radialis brevis branch of radial nerve to anterior interosseous nerve for lower trunk brachial plexopathy after motor vehicle accident. Neurosurg Focus Video 2023; 8:V11. [PMID: 36628091 PMCID: PMC9815233 DOI: 10.3171/2022.10.focvid2287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 10/04/2022] [Indexed: 01/02/2023]
Abstract
The patient is a 15-year-old male who sustained injury to his right lower brachial plexus (C8-T1) in a motor vehicle accident. Six months after the injury, the patient still had persistent hand weakness and wished to regain function in his first and second digits. Transfer of the extensor carpi radialis brevis (ECRB) branch of the radial nerve to the anterior interosseous nerve (AIN) was performed to restore motor function. The patient did well after the surgery, although it may take 12-24 months for benefits to fully manifest. Pertinent surgical anatomy and techniques are highlighted in this video demonstration. The video can be found here: https://stream.cadmore.media/rr10.3171/2022.10.FOCVID2287.
Collapse
Affiliation(s)
- Alison M. Westrup
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Kiana Y. Prather
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Xiaochun Zhao
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Mark E. Stephens
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Andrew H. Jea
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| |
Collapse
|
14
|
Zhao X, Prather KY, Orenday-Barraza JM, Muhammad FY, Villeneuve LM, Cavagnaro MJ, Baaj AA, Dahdaleh NS, Smith ZA. Nontraumatic atlantoaxial rotatory subluxation in adults: Report of two cases. Surg Neurol Int 2022; 13:589. [PMID: 36600765 PMCID: PMC9805632 DOI: 10.25259/sni_936_2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
Background Nontraumatic infectious atlantoaxial rotatory subluxation (AARS) is rare and less frequently encountered in adults versus children. We utilized a stepwise approach to treat two adults with nontraumatic infectious AARS and summarized the relevant literature. Case Description Two patients, ages 35 and 66, presented with classic clinical and imaging findings for infectious nontraumatic AARS. Here, we summarized the management for these two patients along with the literature. Conclusion Nontraumatic infectious AARS in adults requires prompt X-ray diagnosis and timely application of traction to minimize neurological deficits. MR/CT imaging next offers critical information regarding whether operative stabilization is warranted.
Collapse
Affiliation(s)
- Xiaochun Zhao
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Kiana Y. Prather
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | | | - Fauziyya Y. Muhammad
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Lance M. Villeneuve
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - María José Cavagnaro
- Department of Neurosurgery, University of Arizona College of Medicine, Phoenix, Arizona
| | - Ali A. Baaj
- Department of Neurosurgery, University of Arizona College of Medicine, Phoenix, Arizona
| | - Nader S. Dahdaleh
- Department of Neurological Surgery, Northwestern Medicine, Lavin Family Pavilion, Chicago, Illinois, United States
| | - Zachary A. Smith
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma,,Corresponding author: Zachary A. Smith, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
| |
Collapse
|
15
|
Prather KY, O’Neal CM, Westrup AM, Tullos HJ, Hughes KL, Conner AK, Glenn CA, Battiste JD. A systematic review of amino acid PET in assessing treatment response to temozolomide in glioma. Neurooncol Adv 2022; 4:vdac008. [PMID: 35300149 PMCID: PMC8923003 DOI: 10.1093/noajnl/vdac008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The response assessment in neuro-oncology (RANO) criteria have been the gold standard for monitoring treatment response in glioblastoma (GBM) and differentiating tumor progression from pseudoprogression. While the RANO criteria have played a key role in detecting early tumor progression, their ability to identify pseudoprogression is limited by post-treatment damage to the blood-brain barrier (BBB), which often leads to contrast enhancement on MRI and correlates poorly to tumor status. Amino acid positron emission tomography (AA PET) is a rapidly growing imaging modality in neuro-oncology. While contrast-enhanced MRI relies on leaky vascularity or a compromised BBB for delivery of contrast agents, amino acid tracers can cross the BBB, making AA PET particularly well-suited for monitoring treatment response and diagnosing pseudoprogression. The authors performed a systematic review of PubMed, MEDLINE, and Embase through December 2021 with the search terms “temozolomide” OR “Temodar,” “glioma” OR “glioblastoma,” “PET,” and “amino acid.” There were 19 studies meeting inclusion criteria. Thirteen studies utilized [18F]FET, five utilized [11C]MET, and one utilized both. All studies used static AA PET parameters to evaluate TMZ treatment in glioma patients, with nine using dynamic tracer parameters in addition. Throughout these studies, AA PET demonstrated utility in TMZ treatment monitoring and predicting patient survival.
Collapse
Affiliation(s)
- Kiana Y Prather
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Christen M O’Neal
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Alison M Westrup
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Hurtis J Tullos
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Kendall L Hughes
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Andrew K Conner
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Chad A Glenn
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - James D Battiste
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| |
Collapse
|
16
|
Chakraborty AR, Almeida NC, Prather KY, O'Neal CM, Wells AA, Chen S, Conner AK. Resting-state functional magnetic resonance imaging with independent component analysis for presurgical seizure onset zone localization: A systematic review and meta-analysis. Epilepsia 2020; 61:1958-1968. [PMID: 32770853 DOI: 10.1111/epi.16637] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVE One of the greatest challenges of achieving successful surgical outcomes in patients with epilepsy is the ability to properly localize the seizure onset zone (SOZ). Many techniques exist for localizing the SOZ, including intracranial electroencephalography, magnetoencephalography, and stereoelectroencephalography. Recently, resting-state functional magnetic resonance imaging (rs-fMRI) in conjunction with independent component analysis (ICA) has been utilized for presurgical planning of SOZ resection, with varying results. In this meta-analysis, we analyze the current role of rs-fMRI in identifying the SOZ for presurgical planning for patients with drug-resistant epilepsy. Specifically, we seek to demonstrate its current effectiveness compared to other methods of SOZ localization. METHODS A literature review was conducted using the PubMed, MEDLINE, and Embase databases up to May of 2020. A total of 253 articles were screened, and seven studies were chosen for analysis. Each study was analyzed for SOZ localization by ground truth, SOZ localization by rs-fMRI with ICA, principal component analysis, or intrinsic connectivity contrast, and outcomes of surgery. A meta-analysis was performed to analyze how ground truth compares to rs-fMRI in SOZ localization. RESULTS The odds ratio comparing ground truth to rs-fMRI was 2.63 (95% confidence interval = 0.66-10.56). Average concordance of rs-fMRI SOZ localization compared with ground truth localization across studies was 71.3%. SIGNIFICANCE In the hunt for less invasive presurgical planning for epilepsy surgery, rs-fMRI with ICA provides a promising avenue for future standard practice. Our preliminary results show no significant difference in surgical outcomes between traditional standards of SOZ localization and rs-fMRI with ICA. We believe that rs-fMRI could be a step forward in this search. Further investigation comparing rs-fMRI to traditional methods of SOZ localization should be conducted, with the hope of moving toward relying solely on noninvasive screening methods.
Collapse
Affiliation(s)
- Arpan R Chakraborty
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Nyle C Almeida
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Kiana Y Prather
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Christen M O'Neal
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Allison A Wells
- Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Sixia Chen
- Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Andrew K Conner
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| |
Collapse
|