Publications by authors named "Chun-Po Yen"

115 Publications

Clinical characteristics and long-term outcomes for patients who undergo cytoreductive surgery for thoracic meningiomas: a retrospective analysis.

Neurosurg Focus 2021 May;50(5):E18

1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia.

Objective: Primary spinal meningiomas represent a rare indolent neoplasm usually situated in the intradural-extramedullary compartment. They have a predilection for afflicting the thoracic spine and most frequently present with sensory and/or motor symptoms. Resection is the first-line treatment for symptomatic tumors, whereas other clinical factors will determine the need for adjuvant therapy. In this study, the authors aimed to elucidate clinical presentation, functional outcomes, and long-term outcomes in this population in order to better equip clinicians with the tools to counsel their patients.

Methods: This is a retrospective analysis of patients treated at the authors' institution between 1998 and 2018. All patients with thoracic meningiomas who underwent resection and completed at least one follow-up appointment were included. Multiple preoperative clinical variables, hospitalization details, and long-term outcomes were collected for the cohort.

Results: Forty-six patients who underwent resection for thoracic meningiomas were included. The average age of the cohort was 59 years, and the median follow-up was 53 months. Persistent sensory and motor symptoms were present in 29 patients (63%). Fifteen lesions were ventrally positioned. There were 43 WHO grade I tumors, 2 WHO grade II tumors, and 1 WHO grade III tumor; the grade III tumor was the only case of recurrence. The median length of hospitalization was 4 days. Seventeen patients (37%) were discharged to rehabilitation facilities. Thirty patients (65.2%) experienced resolution or improvement of symptoms, and there were no deaths within 30 days of surgery. Only 1 patient developed painful kyphosis and was managed medically. Ventral tumor position, new postoperative deficits, and length of stay did not correlate with disposition to a facility. Age, ventral position, blood loss, and increasing WHO grade did not correlate with length of stay.

Conclusions: Outcomes are overall favorable for patients who undergo resection of thoracic meningiomas. Symptomatic patients often experience improvement, and patients generally do not require significant future operations. Tumors located ventrally, while anatomically challenging, do not necessarily herald a significantly worse prognosis or limit the extent of resection.
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http://dx.doi.org/10.3171/2021.2.FOCUS20977DOI Listing
May 2021

A single-center retrospective analysis of 3- or 4-level anterior cervical discectomy and fusion: surgical outcomes in 66 patients.

J Neurosurg Spine 2020 Oct 9:1-7. Epub 2020 Oct 9.

1Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia; and.

Objective: Anterior cervical discectomy and fusion (ACDF) is a safe and effective intervention to treat cervical spine pathology. Although these were originally performed as single-level procedures, multilevel ACDF has been performed for patients with extensive degenerative disc disease. To date, there is a paucity of data regarding outcomes related to ACDFs of 3 or more levels. The purpose of this study was to compare surgical outcomes of 3- and 4-level ACDF procedures.

Methods: The authors performed a retrospective chart review of patients who underwent 3- and 4-level ACDF at the University of Virginia Health System between January 2010 and December 2017. In patients meeting the inclusion/exclusion criteria, demographics, fusion rates, time to fusion, and reoperation rates were evaluated. Fusion was determined by < 1 mm of change in interspinous distance between individual fused vertebrae on lateral flexion/extension radiographs and lack of radiolucency between the grafts and vertebral bodies. Any procedure requiring a surgical revision was considered a failure.

Results: Sixty-six patients (47 with 3-level and 19 with 4-level ACDFs) met the inclusion/exclusion criteria of having at least one lateral flexion/extension radiograph series ≥ 12 months after surgery. Seventy percent of 3-level patients and 68% of 4-level patients had ≥ 24 months of follow-up. Ninety-four percent of 3-level patients and 100% of 4-level patients achieved radiographic fusion for at least 1 surgical level. Eighty-eight percent and 82% of 3- and 4-level patients achieved fusion at C3-4; 85% and 89% of 3- and 4-level patients achieved fusion at C4-5; 68% and 89% of 3- and 4-level patients achieved fusion at C5-6; 44% and 42% of 3- and 4-level patients achieved fusion at C6-7; and no patients achieved fusion at C7-T1. Time to fusion was not significantly different between levels. Revision was required in 6.4% of patients with 3-level and in 16% of patients with 4-level ACDF. The mean time to revision was 46.2 and 45.4 months for 3- and 4-level ACDF, respectively. The most common reason for revision was worsening of initial symptoms.

Conclusions: The authors' experience with long-segment anterior cervical fusions shows their fusion rates exceeding most of the reported fusion rates for similar procedures in the literature, with rates similar to those reported for short-segment ACDFs. Three-level and 4-level ACDF procedures are viable options for cervical spine pathology, and the authors' analysis demonstrates an equivalent rate of fusion and time to fusion between 3- and 4-level surgeries.
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http://dx.doi.org/10.3171/2020.6.SPINE20171DOI Listing
October 2020

Mini-open lateral retropleural/retroperitoneal approaches for thoracic and thoracolumbar junction anterior column pathologies.

Neurosurg Focus 2020 09;49(3):E13

1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia.

Objective: Advancements in less invasive lateral retropleural/retroperitoneal approaches aim to address the limitation of posterolateral approaches and avoid complications associated with anterior open thoracotomy or thoracoabdominal approaches.

Methods: Consecutive patients treated with a mini-open lateral approach for thoracic or thoracolumbar anterior column pathologies were analyzed in a retrospective case series including clinical and radiographic outcomes. Special attention is given to operative techniques and surgical nuances.

Results: Eleven patients underwent a mini-open lateral retropleural or combined retropleural/retroperitoneal approach for thoracic or thoracolumbar junction lesions. Surgical indications included chronic fracture/deformity (n = 5), acute fracture (n = 2), neoplasm (n = 2), and osteomyelitis (n = 2). The mean length of postoperative hospital stay was 7.2 days (range 2-19 days). All patients ultimately had successful decompression and reconstruction with a mean follow-up of 16.7 months (range 6-29 months). Axial back pain assessed by the visual analog scale improved from a mean score of 8.2 to 2.2. Complications included 1 patient with deep venous thrombosis and pulmonary embolism and 1 with pneumonia. One patient developed increased leg weakness, which subsequently improved. One patient undergoing corpectomy with only lateral plate fixation developed cage subsidence requiring posterior stabilization.

Conclusions: Mini-open lateral retropleural and retroperitoneal corpectomies can safely achieve anterior column reconstruction and spinal deformity correction for various thoracic and thoracolumbar vertebral pathologies.
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http://dx.doi.org/10.3171/2020.6.FOCUS20360DOI Listing
September 2020

Coronal Correction Using Kickstand Rods for Adult Thoracolumbar/Lumbar Scoliosis: Case Series With Analysis of Early Outcomes and Complications.

Oper Neurosurg (Hagerstown) 2020 Sep;19(4):403-413

Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia.

Background: The "kickstand rod technique" has been recently described for achieving and maintaining coronal correction in adult spinal deformity (ASD). Kickstand rods span scoliotic lumbar spine from the thoracolumbar junction proximally to a "kickstand iliac screw" distally. Using the iliac wing as a base, kickstand distraction produces powerful corrective forces. Limited literature exists for this technique, and its associated outcomes and complications are unknown.

Objective: To assess alignment changes, early outcomes, and complications associated with kickstand rod distraction for ASD.

Methods: Consecutive ASD patients treated with kickstand distraction at our institution were retrospectively analyzed.

Results: The cohort comprised 19 patients (mean age: 67 yr; 79% women; 63% prior fusion) with mean follow-up 21 wk (range: 2-72 wk). All patients had posterior-only approach surgery with tri-iliac fixation (third iliac screw for the kickstand) for mean fusion length 12 levels. Three-column osteotomy and lumbar transforaminal lumbar interbody fusion were performed in 5 (26%) and 15 (79%) patients, respectively. Postoperative alignment improved significantly (coronal balance: 8 to 1 cm [P < .001]; major curve: 37° to 12° [P < .001]; fractional curve: 20° to 10° [P < .001]; sagittal balance: 11 to 4 cm [P < .001]; pelvic incidence to lumbar lordosis mismatch: 38° to 9° [P < .001]). Pain Numerical Rating Scale scores improved significantly (back: 7.2 to 4.2 [P = .001]; leg: 5.9 to 1.7 [P = .001]). No instrumentation complications occurred. Motor weakness persisted in 1 patient. There were 3 reoperations (1-PJK, 1-wound dehiscence, and 1-overcorrection).

Conclusion: Among 19 ASD patients treated with kickstand rod distraction, alignment, and back/leg pain improved significantly following surgery. Complication rates were reasonable.
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http://dx.doi.org/10.1093/ons/opaa073DOI Listing
September 2020

Sacral insufficiency fractures after lumbosacral arthrodesis: salvage lumbopelvic fixation and a proposed management algorithm.

J Neurosurg Spine 2020 Mar 27:1-12. Epub 2020 Mar 27.

1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; and.

Objective: Sacral insufficiency fracture after lumbosacral (LS) arthrodesis is an uncommon complication. The objective of this study was to report the authors' operative experience managing this complication, review pertinent literature, and propose a treatment algorithm.

Methods: The authors analyzed consecutive adult patients treated at their institution from 2009 to 2018. Patients who underwent surgery for sacral insufficiency fractures after posterior instrumented LS arthrodesis were included. PubMed was queried to identify relevant articles detailing management of this complication.

Results: Nine patients with a minimum 6-month follow-up were included (mean age 73 ± 6 years, BMI 30 ± 6 kg/m2, 56% women, mean follow-up 35 months, range 8-96 months). Six patients had osteopenia/osteoporosis (mean dual energy x-ray absorptiometry hip T-score -1.6 ± 0.5) and 3 received treatment. Index LS arthrodesis was performed for spinal stenosis (n = 6), proximal junctional kyphosis (n = 2), degenerative scoliosis (n = 1), and high-grade spondylolisthesis (n = 1). Presenting symptoms of back/leg pain (n = 9) or lower extremity weakness (n = 3) most commonly occurred within 4 weeks of index LS arthrodesis, which prompted CT for fracture diagnosis at a mean of 6 weeks postoperatively. All sacral fractures were adjacent or involved S1 screws and traversed the spinal canal (Denis zone III). H-, U-, or T-type sacral fracture morphology was identified in 7 patients. Most fractures (n = 8) were Roy-Camille type II (anterior displacement with kyphosis). All patients underwent lumbopelvic fixation via a posterior-only approach; mean operative duration and blood loss were 3.3 hours and 850 ml, respectively. Bilateral dual iliac screws were utilized in 8 patients. Back/leg pain and weakness improved postoperatively. Mean sacral fracture anterolisthesis and kyphotic angulation improved (from 8 mm/11° to 4 mm/5°, respectively) and all fractures were healed on radiographic follow-up (mean duration 29 months, range 8-90 months). Two patients underwent revision for rod fractures at 1 and 2 years postoperatively. A literature review found 17 studies describing 87 cases; potential risk factors were osteoporosis, longer fusions, high pelvic incidence (PI), and postoperative PI-to-lumbar lordosis (LL) mismatch.

Conclusions: A high index of suspicion is needed to diagnose sacral insufficiency fracture after LS arthrodesis. A trial of conservative management is reasonable for select patients; potential surgical indications include refractory pain, neurological deficit, fracture nonunion with anterolisthesis or kyphotic angulation, L5-S1 pseudarthrosis, and spinopelvic malalignment. Lumbopelvic fixation with iliac screws may be effective salvage treatment to allow fracture healing and symptom improvement. High-risk patients may benefit from prophylactic lumbopelvic fixation at the time of index LS arthrodesis.
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http://dx.doi.org/10.3171/2019.12.SPINE191148DOI Listing
March 2020

Mini-Open Lateral Corpectomy for Thoracolumbar Junction Lesions.

Oper Neurosurg (Hagerstown) 2020 06;18(6):640-647

Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia.

Background: Neoplastic, traumatic, infectious, and degenerative pathologies affecting the thoracolumbar junction pose a unique challenge to spine surgeons. Posterior or anterior approaches have traditionally been utilized to treat these lesions. Although minimally invasive surgeries through a lateral approach to the thoracic or lumbar spine have gained popularity, lateral access to the thoracolumbar junction remains technically challenging due to the overlying diaphragm positioned at the interface of the peritoneum and pleura.

Objective: To describe a mini-open lateral retropleural retroperitoneal approach for pathologies with spinal cord/cauda equina compression at the thoracolumbar junction.

Methods: A mini-open lateral corpectomy is described in detail in a patient with an L1 metastatic tumor.

Results: Satisfactory decompression and spinal column reconstruction were achieved. The patient obtained neural function recovery following the procedure with no intra- or postoperative complications.

Conclusion: The morbidities associated with traditional posterior or anterior approaches to thoracolumbar junction pathologies have led to a growing interest in minimally invasive alternatives. The mini-open lateral approach allows for a safe and efficacious corpectomy and reconstruction for thoracolumbar junction pathologies. Thorough understanding of the anatomy, particularly of the diaphragm, is critical. This approach will have expanded roles in the management of patients with thoracolumbar neoplasms, fractures, infections, deformities, or degenerative diseases.
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http://dx.doi.org/10.1093/ons/opz298DOI Listing
June 2020

Kickstand Rod Technique for Correcting Coronal Imbalance in Adult Scoliosis: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2020 08;19(2):E163-E164

Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia.

Restoration of spinal alignment and balance is a major goal of adult scoliosis surgery. In the past, sagittal alignment has been emphasized and was shown to have the greatest impact on functional outcomes. However, recent evidence suggests the impact of coronal imbalance on pain and functional outcomes has likely been underestimated.1,2 In addition, iatrogenic coronal imbalance may be common and frequently results from inadequate correction of the lumbosacral fractional curve.2,3 The "kickstand rod" is a recently described technique to achieve and maintain significant coronal-plane correction.4 Also, of secondary benefit, the kickstand rod may function as an accessory supplemental rod to offload stress and bolster primary instrumentation. This may reduce occurrence of rod fracture (RF) or pseudarthrosis (PA).5  Briefly, this technique involves positioning the kickstand rod on the side of coronal imbalance (along the major curve concavity or fractional curve convexity in our video demonstration). The kickstand rod spans the thoracolumbar junction proximally to the pelvis distally and is secured with an additional iliac screw placed just superior to the primary iliac screw. By using the iliac wing as a base, powerful distraction forces can reduce the major curve to achieve more normal coronal balance. This operative video illustrates the technical nuances of utilizing the kickstand rod technique for correction of severe lumbar scoliosis and coronal malalignment in a 60-yr-old male patient. Alignment correction was achieved and maintained without evidence of RF/PA after nearly 6 mo postoperatively. The patient gave informed consent for surgery and to use imaging for medical publication.
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http://dx.doi.org/10.1093/ons/opz306DOI Listing
August 2020

Surgical correction of severe adult lumbar scoliosis (major curves ≥ 75°): retrospective analysis with minimum 2-year follow-up.

J Neurosurg Spine 2019 Jun 21:1-14. Epub 2019 Jun 21.

1Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia.

Objective: Prior reports have demonstrated the efficacy of surgical correction for adult lumbar scoliosis. Many of these reports focused on mild to moderate scoliosis. The authors' objective was to report their experience and to assess outcomes and complications after deformity correction for severe adult scoliosis.

Methods: The authors retrospectively analyzed consecutive adult scoliosis patients with major thoracolumbar/lumbar (TL/L) curves ≥ 75° who underwent deformity correction at their institution. Those eligible with a minimum 2 years of follow-up were included. Demographic, surgical, coronal and sagittal plane radiographic measurements, and health-related quality of life (HRQL) scores were analyzed.

Results: Among 26 potentially eligible patients, 22 (85%) had a minimum 2 years of follow-up (range 24-89 months) and were included in the study (mean age 57 ± 11 years; 91% women). The cohort comprised 16 (73%), 4 (18%), and 2 (9%) patients with adult idiopathic scoliosis, de novo degenerative scoliosis, and iatrogenic scoliosis, respectively. The surgical approach was posterior-only and multistage anterior-posterior in 18 (82%) and 4 (18%) patients, respectively. Three-column osteotomy was performed in 5 (23%) patients. Transforaminal and anterior lumbar interbody fusion were performed in 14 (64%) and 4 (18%) patients, respectively. All patients had sacropelvic fixation with uppermost instrumented vertebra in the lower thoracic spine (46% [10/22]) versus upper thoracic spine (55% [12/22]). The mean fusion length was 14 ± 3 levels. Preoperative major TL/L and lumbosacral fractional (L4-S1) curves were corrected from 83° ± 8° to 28° ± 13° (p < 0.001) and 34° ± 8° to 13° ± 6° (p < 0.001), respectively. Global coronal and sagittal balance significantly improved from 5 ± 4 cm to 1 ± 1 cm (p = 0.001) and 9 ± 8 cm to 2 ± 3 cm (p < 0.001), respectively. Pelvic tilt significantly improved from 33° ± 9° to 23° ± 10° (p < 0.001). Significant improvement in HRQL measures included the following: Scoliosis Research Society (SRS) pain score (p = 0.009), SRS appearance score (p = 0.004), and SF-12/SF-36 physical component summary (PCS) score (p = 0.026). Transient and persistent neurological deficits occurred in 8 (36%) and 2 (9%) patients, respectively. Rod fracture/pseudarthrosis occurred in 6 (27%) patients (supplemental rods were utilized more recently in 23%). Revisions were performed in 7 (32%) patients.

Conclusions: In this single-center surgical series for severe adult scoliosis (major curves ≥ 75°), a posterior-only or multistage anterior-posterior approach provided major curve correction of 66% and significant improvements in global coronal and sagittal spinopelvic alignment. Significant improvements were also demonstrated in HRQL measures (SRS pain, SRS appearance, and SF-12/SF-36 PCS). Complications and revisions were comparable to those of other reports involving less severe scoliosis. The results of this study warrant future prospective multicenter studies to further delineate outcomes and complication risks for severe adult scoliosis correction.
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http://dx.doi.org/10.3171/2019.3.SPINE1966DOI Listing
June 2019

Rotational thromboelastometry-guided transfusion during lumbar pedicle subtraction osteotomy for adult spinal deformity: preliminary findings from a matched cohort study.

Neurosurg Focus 2019 04;46(4):E17

Departments of1Neurosurgery and.

OBJECTIVESignificant blood loss and coagulopathy are often encountered during adult spinal deformity (ASD) surgery, and the optimal intraoperative transfusion algorithm is debatable. Rotational thromboelastometry (ROTEM), a functional viscoelastometric method for real-time hemostasis testing, may allow early identification of coagulopathy and improve transfusion practices. The objective of this study was to investigate the effect of ROTEM-guided blood product management on perioperative blood loss and transfusion requirements in ASD patients undergoing correction with pedicle subtraction osteotomy (PSO).METHODSThe authors retrospectively reviewed patients with ASD who underwent single-level lumbar PSO at the University of Virginia Health System. All patients who received ROTEM-guided blood product transfusion between 2015 and 2017 were matched in a 1:1 ratio to a historical cohort treated using conventional laboratory testing (control group). Co-primary outcomes were intraoperative estimated blood loss (EBL) and total blood product transfusion volume. Secondary outcomes were perioperative transfusion requirements and postoperative subfascial drain output.RESULTSThe matched groups (ROTEM and control) comprised 17 patients each. Comparison of matched group baseline characteristics demonstrated differences in female sex and total intraoperative dose of intravenous tranexamic acid (TXA). Although EBL was comparable between ROTEM versus control (3200.00 ± 2106.24 ml vs 3874.12 ± 2224.22 ml, p = 0.36), there was a small to medium effect size (Cohen's d = 0.31) on EBL reduction with ROTEM. The ROTEM group had less total blood product transfusion volume (1624.18 ± 1774.79 ml vs 2810.88 ± 1847.46 ml, p = 0.02), and the effect size was medium to large (Cohen's d = 0.66). This difference was no longer significant after adjusting for TXA (β = -0.18, 95% confidence interval [CI] -1995.78 to 671.64, p = 0.32). More cryoprecipitate and less fresh frozen plasma (FFP) were transfused in the ROTEM group patients (cryoprecipitate units: 1.24 ± 1.20 vs 0.53 ± 1.01, p = 0.03; FFP volume: 119.76 ± 230.82 ml vs 673.06 ± 627.08 ml, p < 0.01), and this remained significant after adjusting for TXA (cryoprecipitate units: β = 0.39, 95% CI 0.05 to 1.73, p = 0.04; FFP volume: β = -0.41, 95% CI -772.55 to -76.30, p = 0.02). Drain output was lower in the ROTEM group and remained significant after adjusting for TXA.CONCLUSIONSFor ASD patients treated using lumbar PSO, more cryoprecipitate and less FFP were transfused in the ROTEM group compared to the control group. These preliminary findings suggest ROTEM-guided therapy may allow early identification of hypofibrinogenemia, and aggressive management of this may reduce blood loss and total blood product transfusion volume. Additional prospective studies of larger cohorts are warranted to identify the appropriate subset of ASD patients who may benefit from intraoperative ROTEM analysis.
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http://dx.doi.org/10.3171/2019.1.FOCUS18572DOI Listing
April 2019

Low rates of complications after spinopelvic fixation with iliac screws in 260 adult patients with a minimum 2-year follow-up.

J Neurosurg Spine 2019 Feb 1:1-9. Epub 2019 Feb 1.

OBJECTIVERecent literature describing complications associated with spinopelvic fixation with iliac screws in adult patients has been limited but has suggested high complication rates. The authors' objective was to report their experience with iliac screw fixation in a large series of patients with a 2-year minimum follow-up.METHODSOf 327 adult patients undergoing spinopelvic fixation with iliac screws at the authors' institution between 2010 and 2015, 260 met the study inclusion criteria (age ≥ 18 years, first-time iliac screw placement, and 2-year minimum follow-up). Patients with active spinal infection were excluded. All iliac screws were placed via a posterior midline approach using fluoroscopic guidance. Iliac screw heads were deeply recessed into the posterior superior iliac spine. Clinical and radiographic data were obtained and analyzed.RESULTSTwenty patients (7.7%) had iliac screw-related complication, which included fracture (12, 4.6%) and/or screw loosening (9, 3.5%). No patients had iliac screw head prominence that required revision surgery or resulted in pain, wound dehiscence, or poor cosmesis. Eleven patients (4.2%) had rod or connector fracture below S1. Overall, 23 patients (8.8%) had L5-S1 pseudarthrosis. Four patients (1.5%) had fracture of the S1 screw. Seven patients (2.7%) had wound dehiscence (unrelated to the iliac screw head) or infection. The rate of reoperation (excluding proximal junctional kyphosis) was 17.7%. On univariate analysis, an iliac screw-related complication rate was significantly associated with revision fusion (70.0% vs 41.2%, p = 0.013), a greater number of instrumented vertebrae (mean 12.6 vs 10.3, p = 0.014), and greater postoperative pelvic tilt (mean 27.7° vs 23.2°, p = 0.04). Lumbosacral junction-related complications were associated with a greater mean number of instrumented vertebrae (12.6 vs 10.3, p = 0.014). Reoperation was associated with a younger mean age at surgery (61.8 vs 65.8 years, p = 0.014), a greater mean number of instrumented vertebrae (12.2 vs 10.2, p = 0.001), and longer clinical and radiological mean follow-up duration (55.8 vs 44.5 months, p < 0.001; 55.8 vs 44.6 months, p < 0.001, respectively). On multivariate analysis, reoperation was associated with longer clinical follow-up (p < 0.001).CONCLUSIONSPrevious studies on iliac screw fixation have reported very high rates of complications and reoperation (as high as 53.6%). In this large, single-center series of adult patients, iliac screws were an effective method of spinopelvic fixation that had high rates of lumbosacral fusion and far lower complication rates than previously reported. Collectively, these findings argue that iliac screw fixation should remain a favored technique for spinopelvic fixation.
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http://dx.doi.org/10.3171/2018.9.SPINE18239DOI Listing
February 2019

Radiographic outcome and complications after single-level lumbar extended pedicle subtraction osteotomy for fixed sagittal malalignment: a retrospective analysis of 55 adult spinal deformity patients with a minimum 2-year follow-up.

J Neurosurg Spine 2018 11;30(2):242-252

OBJECTIVEFixed sagittal spinal malalignment is a common problem in adult spinal deformity (ASD). Various three-column osteotomy techniques, including the extended pedicle subtraction osteotomy (ePSO), may correct global and regional malalignment in this patient population. In contrast to the number of reports on traditional PSO (Schwab grade 3 osteotomy), there is limited literature on the outcomes of ePSO (Schwab grade 4 osteotomy) in ASD surgery. The objective of this retrospective study was to provide focused investigation of radiographic outcomes and complications of single-level lumbar ePSO for ASD patients with fixed sagittal malalignment.METHODSConsecutive ASD patients in whom sagittal malalignment had been treated with single-level lumbar ePSO at the authors' institution between 2010 and 2015 were analyzed, and those with a minimum 2-year follow-up were included in the study. Radiographic analyses included assessments of segmental lordosis through the ePSO site (sagittal Cobb angle measured from the superior endplate of the vertebra above and inferior endplate of the vertebra below the ePSO), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence and LL mismatch, thoracic kyphosis (TK), and sagittal vertical axis (SVA) on standing long-cassette radiographs. Complications were analyzed for the entire group.RESULTSAmong 71 potentially eligible patients, 55 (77%) had a minimum 2-year follow-up and were included in the study. Overall, the average postoperative increases in ePSO segmental lordosis and overall LL were 41° ± 14° (range 7°-69°, p < 0.001) and 38° ± 11° (range 9°-58°, p < 0.001), respectively. The average SVA improvement was 13 ± 7 cm (range of correction: -33.6 to 3.4 cm, p < 0.001). These measurements were maintained when comparing early postoperative to last follow-up values, respectively (mean follow-up 52 months, range 26-97 months): ePSO segmental lordosis, 34° vs 33°, p = 0.270; LL, 47.3° vs 46.7°, p = 0.339; and SVA, 4 vs 5 cm, p = 0.330. Rod fracture (RF) at the ePSO site occurred in 18.2% (10/55) of patients, and pseudarthrosis (PA) at the ePSO site was confirmed by CT imaging or during rod revision surgery in 14.5% (8/55) of patients. Accessory supplemental rods across the ePSO site, a more recently employed technique, significantly reduced the occurrence of RF or PA on univariate (p = 0.004) and multivariable (OR 0.062, 95% CI 0.007-0.553, p = 0.013) analyses; this effect approached statistical significance on Kaplan-Meier analysis (p = 0.053, log-rank test). Interbody cage placement at the ePSO site resulted in greater ePSO segmental lordosis correction (45° vs 35°, p = 0.007) without significant change in RF or PA (p = 0.304). Transient and persistent motor deficits occurred in 14.5% (8/55) and 1.8% (1/55) of patients, respectively.CONCLUSIONSExtended PSO is an effective technique to correct fixed sagittal malalignment for ASD. In comparison to traditional PSO techniques, ePSO may allow greater focal correction with comparable complication rates, especially with interbody cage placement at the ePSO site and the use of accessory supplemental rods.
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http://dx.doi.org/10.3171/2018.7.SPINE171367DOI Listing
November 2018

Extended Asymmetrical Pedicle Subtraction Osteotomy for Adult Spinal Deformity: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2019 Feb;16(2):52-53

Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia.

Pedicle subtraction osteotomy (PSO) is an effective technique to correct fixed sagittal malalignment. A variation of this technique, the "trans-discal" or "extended" PSO (Schwab grade IV osteotomy), involves extending the posterior wedge resection of the index vertebra to include the superior adjacent disc for radical discectomy. The posterior wedge may be resected in asymmetric fashion to correct concurrent global coronal malalignment.This video illustrates the technical nuances of an extended asymmetrical lumbar PSO for adult spinal deformity. A 62-yr-old female with multiple prior lumbar fusions presented with worsening back pain and posture. Preoperative scoliosis X-rays demonstrated severe global sagittal and coronal malalignment (sagittal vertical axis [SVA, C7-plumbline] of 13.5 cm, pelvic incidence [PI] of 60°, lumbar lordosis [LL] of 14° [in kyphosis], pelvic tilt [PT] of 61°, thoracic kyphosis [TK] of 18°, and rightward coronal shift of 9.3 cm). The patient gave informed consent to surgery and for use of her imaging for medical publication. Briefly, surgery first involved transpedicular instrumentation from T10 to S1 with bilateral iliac screw fixation, and then T11-12 and T12-L1 Smith-Petersen osteotomies were performed. Next, an extended asymmetrical L4 PSO was performed and a 12° lordotic cage (9 × 14 × 40 mm) was placed at the PSO defect. Rods were placed from T10 to iliac bilaterally, and accessory supplemental rods spanning the PSO were attached. Postoperative scoliosis X-rays demonstrated improved alignment: SVA 5.5 cm, PI 60°, LL 55°, PT 36°, TK 37°, and 3.7 cm of rightward coronal shift. The patient had uneventful recovery.
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http://dx.doi.org/10.1093/ons/opy160DOI Listing
February 2019

A Novel Junctional Tether Weave Technique for Adult Spinal Deformity: 2-Dimensional Operative Video.

Oper Neurosurg (Hagerstown) 2019 Feb;16(2):45-46

Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia.

Proximal junctional kyphosis (PJK) is a common problem after multilevel spine instrumentation for adult spinal deformity. Various anti-PJK techniques such as junctional tethers for ligamentous augmentation have been proposed. We present an operative video demonstrating technical nuances of junctional tether "weave" application. A 70-yr-old male with prior L2-S1 instrumented fusion presented with worsening back pain and posture. Imaging demonstrated pathological loss of lumbar lordosis (flat back deformity), proximal junctional failure, and pseudarthrosis. The patient had severe global and segmental sagittal malalignment, with sagittal vertical axis (SVA, C7-plumbline) measuring 22.3 cm, pelvic incidence (PI) 55°, lumbar lordosis (LL) 8° in kyphosis, pelvic tilt (PT) 30°, and thoracic kyphosis (TK) 6°. The patient gave informed consent for surgery and use of imaging for medical publication. Briefly, surgery first involved re-instrumentation with bilateral pedicle screws from T10 to S1. After right-sided iliac screw fixation (left-sided iliac screw fixation was not performed due to extensive prior iliac crest bone graft harvesting), we then completed a L2-3 Smith-Petersen osteotomy, extended L4 pedicle subtraction osteotomy, and L3-4 interbody arthrodesis with a 12° lordotic cage (9 × 14 × 40 mm). Cobalt Chromium rods were placed spanning the instrumentation bilaterally, and accessory supplemental rods spanning the PSO were attached. An anti-PJK junctional tether "weave" was then implemented using 4.5 mm polyethylene tape (Mersilene tape [Ethicon, Somerville, New Jersey]). Postoperative imaging demonstrated improved alignment (SVA 2.8 cm, PI 55°, LL 53°, PT 25°, TK 45°) and no significant neurological complications occurred during convalescence or at 6 mo postop.
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http://dx.doi.org/10.1093/ons/opy148DOI Listing
February 2019

Biomechanical study of rod stress after pedicle subtraction osteotomy versus anterior column reconstruction: A finite element study.

Surg Neurol Int 2017 6;8:207. Epub 2017 Sep 6.

Department of Neurosurgery, University of South Florida, Tampa, Florida, USA.

Background: In an effort to minimize rod fractures and nonunion in pedicle subtraction osteotomy (PSO) constructs, surgeons have adopted multirod constructs and interbody cages. Anterior column realignment (ACR) with posterior column osteotomies is a minimally invasive alternative to PSO in sagittal balance correction, however, there is a paucity of evidence with respect to rod survival.

Methods: Three-dimensional (3D) finite-element-model of a T12-sacrum spine segment was used to compare a 25° PSO at L3 and an ACR with a posterior column osteotomy and 30° hyperlordotic interbody cage at L3-4. The amount of overall T12-S1 lordosis correction was the same for each condition. Each simulation included cobalt chromium alloy primary rods with: (1) PSO; (2) PSO with an interbody cage (IB) at L2-3 (PSO+IB); (3) PSO with accessory (A) rods and IB at L2-3 (PSO+IB+A); (4) PSO with satellite (S) rods and IB at L2-3 (PSO+IB+2S); (5) ACR; 6) ACR with satellite rods (ACR + 2S). A 400 follower preload was simulated for each condition.

Results: PSO condition had the largest rod stress of 286 MPa in flexion. Adding interbody support reduced the rod stress by 15%. The 4-rod constructs further reduced rod stress, with the satellite rod condition facilitating the largest reduction. The rod stress in the ACR+2S was equivalent to the PSO+2S, with 50% reduction in rod stress.

Conclusion: The rod stress with an ACR was comparable to a PSO coupled with interbody support. These results suggest an ACR is a viable MIS alternative to a PSO without the need for a large posterior osteotomy.
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http://dx.doi.org/10.4103/sni.sni_44_17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5609360PMC
September 2017

Mini-open Lateral Retropleural Approach for Symptomatic Thoracic Disk Herniations.

Clin Spine Surg 2018 02;31(1):14-21

Department of Neurological Surgery, University of South Florida, Tampa, FL.

Background: Surgeries for symptomatic thoracic disk herniations (TDH) remain challenging.

Objective: A mini-open lateral retropleural approach is described and the clinical outcomes are reported.

Materials And Methods: A total of 23 patients underwent mini-open lateral retropleural diskectomy. Patients were placed in a lateral position. A 5-cm lateral incision was made followed by resection of the rib after careful dissection of its undersurface from the endothoracic fascia. The fascia was incised and separated from parietal pleura to widen the retropleural space. The rib head was removed followed by a pedicle resection below the TDH to expose the dura. A posterior partial corpectomy above and below the disk was performed to create a space ventral to the TDH, which was later dissected away from the dura and removed.

Results: Fourteen males and 9 females comprised the clinical cohort. Five presented with axial back pain, 7 with radicular pain and 11 with myelopathy. All but 2 disks were successfully removed. The mean blood loss was 214cc and the mean hospital stay was 5.3 days. There was no mortality or new neurological deficits. The mean follow-up was 15.4 months.

Conclusions: Mini-open lateral retropleural approach is safe and effective to remove symptomatic TDH with minimal morbidities and fast patient recovery.
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http://dx.doi.org/10.1097/BSD.0000000000000580DOI Listing
February 2018

Effects of intradiscal vacuum phenomenon on surgical outcome of lateral interbody fusion for degenerative lumbar disease.

J Neurosurg Spine 2017 Apr 16;26(4):419-425. Epub 2016 Dec 16.

Department of Neurological Surgery, University of South Florida, Tampa, Florida; and.

OBJECTIVE The authors investigated whether the presence of intradiscal vacuum phenomenon (IVP) results in greater correction of disc height and restoration of segmental lordosis (SL). METHODS A retrospective chart review was performed on every patient at the University of South Florida's Department of Neurosurgery treated with lateral lumbar interbody fusion between 2011 and 2015. From these charts, preoperative plain radiographs and CT images were reviewed for the presence of IVP. Preoperative and postoperative posterior disc height (PDH), anterior disc height (ADH), and SL were measured at disc levels with IVP and compared with those at disc levels without IVP using the t-test. Linear regression was used to evaluate the factors that predict changes in PDH, ADH, and SL. RESULTS One hundred forty patients with 247 disc levels between L-1 and L-5 were treated with lateral lumbar interbody fusion. Among all disc levels treated, the mean PDH increased from 3.69 to 6.66 mm (p = 0.011), the mean ADH increased from 5.45 to 11.53 mm (p < 0.001), and the mean SL increased from 9.59° to 14.55° (p < 0.001). Significantly increased PDH was associated with the presence of IVP, addition of pedicle screws, and lack of cage subsidence; significantly increased ADH was associated with the presence of IVP, anterior longitudinal ligament (ALL) release, addition of pedicle screws, and lack of subsidence; and significantly increased SL was associated with the presence of IVP and ALL release. CONCLUSIONS IVP in patients with degenerative spinal disease remains grossly underreported. The data from the present study suggest that the presence of IVP results in increased restoration of disc height and SL.
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http://dx.doi.org/10.3171/2016.8.SPINE16421DOI Listing
April 2017

Worse Outcomes After Repeat vs Initial Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations: A Retrospective Matched-Cohort Study.

Neurosurgery 2016 Nov;79(5):690-700

Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia.

Background: Incompletely obliterated cerebral arteriovenous malformations (AVMs) after initial treatment with stereotactic radiosurgery (SRS) can be treated with a repeat session of SRS. However, the relative efficacy of repeat vs initial SRS is not well specified.

Objective: To retrospectively compare in matched cohorts the outcomes of repeat vs initial SRS for the treatment of matched cohorts with angioarchitecturally similar AVMs.

Methods: We studied a data set of patients with AVM treated with radiosurgery during the period spanning 1989 to 2013. Patients with AVM who underwent repeat SRS with radiologic follow-up of ≥2 years or nidus obliteration were identified for the study and matched, in a 1:1 fashion that was blinded to outcome, to patients with previously untreated AVMs who underwent initial SRS. Statistical analyses were performed to compare the outcomes after repeat vs initial SRS.

Results: The matching approach resulted in 84 patients for the repeat and the initial SRS cohort (mean margin doses, 20.7 and 20.9 Gy, respectively; P = .74). In the repeat SRS cohort, obliteration was achieved in 67%; the radiologic, symptomatic, and permanent radiation-induced change rates were 35%, 10%, and 4%, respectively; and the post-SRS hemorrhage rate was 3.1%/y. Compared with the initial SRS cohort, the repeat SRS cohort had significantly lower obliteration rates (P = .04) and higher post-SRS hemorrhage rates (P = .04). The radiation-induced change rates of the 2 cohorts were not significantly different.

Conclusion: Repeat SRS yields considerably poorer outcomes than initial SRS for angioarchitecturally comparable AVMs. Further studies in AVM radiobiology and vascular structure are necessary to elucidate this potentially differential response.

Abbreviations: AVM, arteriovenous malformationRIC, radiation-induced changeRBAS, radiosurgery-based arteriovenous malformation scoreSRS, stereotactic radiosurgeryVRAS, virginia radiosurgery AVM scale.
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http://dx.doi.org/10.1227/NEU.0000000000001409DOI Listing
November 2016

Role of minimally invasive surgery for adult spinal deformity in preventing complications.

Curr Rev Musculoskelet Med 2016 Sep;9(3):309-15

Department of Neurological Surgery, University of South Florida, Tampa, FL, USA.

With the aging population, there is a rising prevalence of degenerative spinal deformity and need of surgical care for these patients. Surgical treatment for adult spinal deformity (ASD) is often fraught with a high rate of complications. Minimally invasive surgery (MIS) has for the past decade been adopted by spine surgeons to treat ASD in the hopes of reducing access-related morbidity and perioperative complications. The benefits of MIS approach in general and recent development of MIS techniques to avoid long-term complications such as pseudoarthrosis or proximal junctional kyphosis are reviewed.
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http://dx.doi.org/10.1007/s12178-016-9355-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4958387PMC
September 2016

Stereotactic radiosurgery for cerebral arteriovenous malformations: evaluation of long-term outcomes in a multicenter cohort.

J Neurosurg 2017 Jan 4;126(1):36-44. Epub 2016 Mar 4.

Department of Neurosurgery, University of Virginia, Charlottesville, Virginia.

OBJECTIVE In this multicenter study, the authors reviewed the results following Gamma Knife radiosurgery (GKRS) of cerebral arteriovenous malformations (AVMs), determined predictors of outcome, and assessed predictive value of commonly used grading scales based upon this large cohort with long-term follow-up. METHODS Data from a cohort of 2236 patients undergoing GKRS for cerebral AVMs were compiled from the International Gamma Knife Research Foundation. Favorable outcome was defined as AVM obliteration and no posttreatment hemorrhage or permanent symptomatic radiation-induced complications. Patient and AVM characteristics were assessed to determine predictors of outcome, and commonly used grading scales were assessed. RESULTS The mean maximum AVM diameter was 2.3 cm, with a mean volume of 4.3 cm. A mean margin dose of 20.5 Gy was delivered. Mean follow-up was 7 years (range 1-20 years). Overall obliteration was 64.7%. Post-GRKS hemorrhage occurred in 165 patients (annual risk 1.1%). Radiation-induced imaging changes occurred in 29.2%; 9.7% were symptomatic, and 2.7% had permanent deficits. Favorable outcome was achieved in 60.3% of patients. Patients with prior nidal embolization (OR 2.1, p < 0.001), prior AVM hemorrhage (OR 1.3, p = 0.007), eloquent location (OR 1.3, p = 0.029), higher volume (OR 1.01, p < 0.001), lower margin dose (OR 0.9, p < 0.001), and more isocenters (OR 1.1, p = 0.011) were more likely to have unfavorable outcomes in multivariate analysis. The Spetzler-Martin grade and radiosurgery-based AVM score predicted outcome, but the Virginia Radiosurgery AVM Scale provided the best assessment. CONCLUSIONS GKRS for cerebral AVMs achieves obliteration and avoids permanent complications in the majority of patients. Patient, AVM, and treatment parameters can be used to predict long-term outcomes following radiosurgery.
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http://dx.doi.org/10.3171/2015.9.JNS151311DOI Listing
January 2017

Procedural Checklist for Retroperitoneal Transpsoas Minimally Invasive Lateral Interbody Fusion.

Spine (Phila Pa 1976) 2016 Apr;41 Suppl 8:S152-8

*Department of Neurological Surgery, University of South Florida, Tampa, FL †Department of Neurological Surgery, University of Virginia, Charlottesville, VA.

Study Design: An expert opinion.

Objective: The aim of this study is to provide an overview of the surgical technique with an emphasis on complication avoidance techniques and to present a procedural checklist for the retroperitoneal transpsoas minimally invasive lateral approach.

Summary Of Background Data: Although the minimally invasive lateral interbody fusion has gained popularity in the past decade, complication rate variability remains in the literature, driven by inconsistent adherence to technique, neuromonitoring, and complication avoidance techniques.

Methods: The surgical and complication avoidance techniques for extreme lateral interbody fusion are presented in a stepwise fashion from the practice of an experienced lateral approach surgeon.

Results: The technical description and procedural checklist cover preoperative assessment, operating room setup, patient positioning, surgical procedure, and postoperative evaluation.

Conclusion: A systematic approach through preoperative assessment, attention to surgical technique and intraoperative neuromonitoring, and a detailed postoperative evaluation are key to achieving the goal of lateral interbody fusion with minimization of procedural morbidity.

Level Of Evidence: 5.
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http://dx.doi.org/10.1097/BRS.0000000000001473DOI Listing
April 2016

Radiosurgery for Cerebral Arteriovenous Malformations with Associated Arterial Aneurysms.

World Neurosurg 2016 Mar 28;87:77-90. Epub 2015 Dec 28.

Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia, USA. Electronic address:

Objective: The radiosurgical outcomes for cerebral arteriovenous malformations (AVM) with AVM-associated arterial aneurysms (AAA) are poorly understood, because many AAAs are embolized before nidal intervention. The aim of this retrospective case-control study is to determine the effect of AAAs on AVM radiosurgery outcomes.

Methods: We evaluated an institutional AVM radiosurgery database from 1989 to 2013. AAAs were classified as intranidal (type I) or prenidal (type II). The case cohort comprised AVMs with patent type I or II AAAs. The control cohort comprised AVMs without AAAs and matched 2:1 to the case cohort.

Results: The case cohort comprised 51 AVMs, including 23 with type I and 28 with type II AAAs. The control cohort comprised 102 AVMs without AAAs. The cumulative AVM obliteration, annual postradiosurgery hemorrhage, and radiologically evident radiation-induced changes rates were 67%, 3.3%, and 28%, respectively, for the case cohort, compared with 70%, 2.0%, and 35%, respectively, for the control cohort. The presence of an AAA was not significantly associated with obliteration (P = 0.293), postradiosurgery hemorrhage (P = 0.209), or radiation-induced changes (P = 0.323). The rates of type II AAA occlusion at 3, 5, and 10 years were 46%, 77%, and 95%, respectively. The type II AAA occlusion rate was significantly higher in obliterated AVMs (P = 0.002).

Conclusions: Patent intranidal or prenidal AAAs do not significantly affect AVM radiosurgical outcomes. Occlusion of distal prenidal AAAs commonly occurs after radiosurgery. These findings may support a more conservative stance for embolization before radiosurgery for AVMs with AAAs.
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http://dx.doi.org/10.1016/j.wneu.2015.11.080DOI Listing
March 2016

Stereotactic Radiosurgery for Partially Resected Cerebral Arteriovenous Malformations.

World Neurosurg 2016 Jan 13;85:263-72. Epub 2015 Oct 13.

Department of Neurological Surgery, Charlottesville, Virginia, USA. Electronic address:

Objective: Incomplete microsurgical resection of cerebral arteriovenous malformations (AVM) occurs uncommonly. However, such patients harboring postoperative residual nidi remain exposed to the risk of AVM hemorrhage and are therefore reasonable candidates for further intervention. The goals of this retrospective case-control study are to analyze the radiosurgery outcomes for partially resected AVMs and determine the effect of prior resection on AVM radiosurgery outcomes.

Methods: We evaluated a prospective database of AVM patients treated with radiosurgery from 1989-2013. Previously resected AVMs with radiologic follow-up ≥2 years or nidus obliteration were selected for analysis and matched, in a 1:1 fashion and blinded to outcome, to previously unresected AVMs. Statistical analyses were performed to assess relationship between prior resection and AVM radiosurgery outcomes.

Results: The matching process yielded 88 patients in each of the previously resected and unresected AVM cohorts. In the resected AVM cohort, the actuarial AVM obliteration rates at 3 and 5 years were 47% and 75%, respectively; the rates of radiologic and symptomatic radiation-induced changes (RICs) were 10% and 3%, respectively; and the annual postradiosurgery hemorrhage risk was 1.1%. The lack of prior AVM resection (P < 0.001) and superficial AVM location (P = 0.009) were independent predictors of radiologic RIC. The actuarial rates of obliteration (P = 0.849) and postradiosurgery hemorrhage (P = 0.548) were not significantly different between the resected and unresected AVM cohorts.

Conclusions: Radiosurgery affords a reasonable risk-to-benefit profile for incompletely resected AVMs. For those with a small-volume residual nidus after resection, radiosurgery should be considered an effective alternative to repeat resection.
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http://dx.doi.org/10.1016/j.wneu.2015.10.001DOI Listing
January 2016

Brainstem metastases treated with stereotactic radiosurgery: safety, efficacy, and dose response.

J Neurooncol 2015 Nov 4;125(2):385-92. Epub 2015 Sep 4.

Department of Radiation Oncology, University of Virginia, 1240 Lee Street, Box 800383, Charlottesville, VA, 22908, USA.

The safety and efficacy of stereotactic radiosurgery (SRS) in the brainstem is questioned by some over concern of violating historical brainstem SRS dose tolerance. Our purpose was to report on the clinical outcomes of patients treated at our institution with radiosurgery for brainstem metastases. Patients with metastatic tumors within or directly abutting the brainstem from 1992 to 2014 were analyzed. Patient and tumor characteristics, SRS parameters, and toxicity were recorded and analyzed for associations with local control and survival. Multivariate statistical analysis was performed using Cox proportional hazards modeling. One-hundred and eighty-nine (189) brainstem metastases from 161 patients were included in our analysis. Whole brain irradiation was administered prior to SRS in 52 % of patients. The median margin dose was 18 Gy prescribed to the 50 % isodose line. Median imaging follow up was 5.4 months and median survival was 5.5 months after SRS. At last follow up, local control was achieved in 87.3 % of brainstem lesions treated. There were 3 recorded events of grade 3-5 toxicity (1.8 %). On multivariate analysis, a margin dose ≥16 Gy was associated with improved local control (p = 0.049) and greater KPS score was associated with improved overall survival following SRS (p = 0.024). Patients with brainstem metastases who have limited intracranial disease and/or who have received whole brain irradiation should be considered for SRS. Margin doses of at least 16 Gy are associated with superior local control, and serious radiation toxicity in SRS for brainstem metastasis appears rare.
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http://dx.doi.org/10.1007/s11060-015-1927-6DOI Listing
November 2015

Cerebral Arteriovenous Malformations and Epilepsy, Part 2: Predictors of Seizure Outcomes Following Radiosurgery.

World Neurosurg 2015 Sep 28;84(3):653-62. Epub 2015 May 28.

Department of Neurosurgery, University of Virginia School of Medicine, Charlottesville, Virginia, USA. Electronic address:

Objective: Seizure outcomes after arteriovenous malformation (AVM) management with radiosurgery are incompletely understood. In this case-control study, we aim to determine the incidences and define the predictors of seizure improvement and de novo seizures in patients with AVM with and without seizures at presentation, respectively.

Methods: We evaluated our institutional AVM radiosurgery database to determine the factors that were associated with favorable seizure outcome (seizure improvement or lack of de novo seizures). In patients with seizures at presentation, seizure improvement was defined as decreased seizure frequency or complete seizure remission. In patients without seizures at presentation, de novo seizures were defined as new-onset seizures after radiosurgery. Logistic regression analyses were performed to identify predictors of favorable seizure outcome.

Results: In 229 patients with seizures at presentation, the rates of seizure improvement and seizure remission were 57% and 20%, respectively. Prior AVM hemorrhage (P = 0.015), longer follow-up (P < 0.0001), and lack of hemorrhage after radiosurgery (P = 0.048) were independent predictors of seizure improvement in the multivariate analysis. In 778 patients without seizures at presentation, the overall rate of de novo seizures was 1.7%. Prior AVM hemorrhage (P = 0.001) and higher Spetzler-Martin grade (P = 0.018) were independent predictors of the absence of de novo seizures in the multivariate analysis. AVM obliteration was not significantly associated with seizure outcomes after radiosurgery.

Conclusions: Radiosurgery provides reasonable rates of seizure improvement for patients with AVM who present with seizures. For patients with AVM without seizures at presentation, the risk of de novo seizures after radiosurgery is very low, obviating the need for prophylactic antiepileptic drug therapy. Further investigation of epilepsy in patients with AVM undergoing stereotactic radiosurgery should be considered with validated outcome measures and prospective study design.
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http://dx.doi.org/10.1016/j.wneu.2015.04.064DOI Listing
September 2015

Radiosurgery for Cerebral Arteriovenous Malformations in Elderly Patients: Effect of Advanced Age on Outcomes After Intervention.

World Neurosurg 2015 Sep 18;84(3):795-804. Epub 2015 May 18.

Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia, USA. Electronic address:

Objective: Cerebral arteriovenous malformations (AVM) are infrequently diagnosed and treated in elderly patients (age, >60 years). We hypothesize that, in contrast to AVM surgical outcomes, radiosurgery outcomes are not adversely affected by increased age. The goals of this case-control study are to analyze the radiosurgery outcomes for elderly patients with AVMs and determine the effect of elderly age on AVM radiosurgery outcomes.

Methods: We evaluated a prospective database of patients with AVMs treated with radiosurgery from 1989 to 2013. Elderly patients with AVM (age, ≥ 60 years) with radiologic follow-up of ≥ 2 years or nidus obliteration were selected for analysis, and matched, in a 1:1 fashion and blinded to outcome, to adult nonelderly patients with AVM (age, <60 years). Statistical analyses were performed to determine actuarial obliteration rates and evaluate the relationship between elderly age and AVM radiosurgery outcomes.

Results: The matching processes yielded 66 patients in each of the elderly and nonelderly AVM cohorts. In the elderly AVM cohort, the actuarial AVM obliteration rates at 3, 5, and 10 years were 37%, 65%, and 77%, respectively; the rates of radiologically evident, symptomatic, and permanent radiation-induced changes were 36%, 11%, and 0%, respectively; the annual hemorrhage risk after radiosurgery was 1.1%, and the AVM-related mortality rate was 1.5%. Elderly age was not significantly associated with AVM obliteration, radiation-induced changes, or hemorrhage after radiosurgery.

Conclusions: Advanced age does not appear to confer appreciably worse AVM radiosurgery outcomes, unlike its negative effect on AVM surgical outcomes. Thus, when an AVM warrants treatment, radiosurgery may be the preferred treatment for elderly patients.
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http://dx.doi.org/10.1016/j.wneu.2015.05.012DOI Listing
September 2015

Radiosurgery for temporal lobe arteriovenous malformations: effect of temporal location on seizure outcomes.

J Neurosurg 2015 Oct 17;123(4):924-34. Epub 2015 Apr 17.

Departments of 1 Neurological Surgery and.

Object: The temporal lobe is particularly susceptible to epileptogenesis. However, the routine use of anticonvulsant therapy is not implemented in temporal lobe AVM patients without seizures at presentation. The goals of this case-control study were to determine the radiosurgical outcomes for temporal lobe AVMs and to define the effect of temporal lobe location on postradiosurgery AVM seizure outcomes.

Methods: From a database of approximately 1400 patients, the authors generated a case cohort from patients with temporal lobe AVMs with at least 2 years follow-up or obliteration. A control cohort with similar baseline AVM characteristics was generated, blinded to outcome, from patients with non-temporal, cortical AVMs. They evaluated the rates and predictors of seizure freedom or decreased seizure frequency in patients with seizures or de novo seizures in those without seizures.

Results: A total of 175 temporal lobe AVMs were identified based on the inclusion criteria. Seizure was the presenting symptom in 38% of patients. The median AVM volume was 3.3 cm3, and the Spetzler-Martin grade was III or higher in 39% of cases. The median radiosurgical prescription dose was 22 Gy. At a median clinical follow-up of 73 months, the rates of seizure control and de novo seizures were 62% and 2%, respectively. Prior embolization (p = 0.023) and lower radiosurgical dose (p = 0.027) were significant predictors of seizure control. Neither temporal lobe location (p = 0.187) nor obliteration (p = 0.522) affected seizure outcomes. The cumulative obliteration rate was 63%, which was significantly higher in patients without seizures at presentation (p = 0.046). The rates of symptomatic and permanent radiation-induced changes were 3% and 1%, respectively. The annual risk of postradiosurgery hemorrhage was 1.3%.

Conclusions: Radiosurgery is an effective treatment for temporal lobe AVMs. Furthermore, radiosurgery is protective against seizure progression in patients with temporal lobe AVM-associated seizures. Temporal lobe location does not affect radiosurgery-induced seizure control. The low risk of new-onset seizures in patients with temporal or extratemporal AVMs does not seem to warrant prophylactic use of anticonvulsants.
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http://dx.doi.org/10.3171/2014.10.JNS141807DOI Listing
October 2015

Effect of Prior Embolization on Cerebral Arteriovenous Malformation Radiosurgery Outcomes: A Case-Control Study.

Neurosurgery 2015 Sep;77(3):406-17; discussion 417

*Mount Sinai Health System, Department of Neurosurgery, New York City, New York; ‡University of Virginia, Department of Neurosurgery, Charlottesville, Virginia; §New York University Langone Medical Center, Department of Neurosurgery, New York City, New York.

Background: Embolization before stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVM) has been shown to negatively affect obliteration rates, but its impact on the risks of radiosurgery-induced complications and latency period hemorrhage is poorly defined.

Objective: To determine, in a case-control study, the effect of prior embolization on AVM SRS outcomes.

Methods: We evaluated a database of AVM patients who underwent SRS. Propensity score analysis was used to match the case (embolized nidi) and control (nonembolized nidi) cohorts. AVM angioarchitectural complexity was defined as the sum of the number of major feeding arteries and draining veins to the nidus. Multivariate Cox proportional hazards regression analyses were performed on the overall study population to determine independent predictors of obliteration and radiation-induced changes.

Results: The matching process yielded 242 patients in each cohort. The actuarial obliteration rates were significantly lower in the embolized (31%, 49% at 5, 10 years, respectively) compared with the nonembolized (48%, 64% at 5, 10 years, respectively) cohort (P = .003). In the multivariate analysis for obliteration, lower angioarchitectural complexity (P < .001) and radiologically evident radiation-induced changes (P = .016) were independent predictors, but embolization was not significant (P = .744). In the multivariate analysis for radiologic radiation-induced changes, lack of prior embolization (P = .009) and fewer draining veins (P = .011) were independent predictors.

Conclusion: The effect of prior embolization on AVM obliteration after SRS may be significantly confounded by nidus angioarchitectural complexity. Additionally, embolization could reduce the risk of radiation-induced changes. Thus, combined embolization and SRS may be warranted for appropriately selected nidi.
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http://dx.doi.org/10.1227/NEU.0000000000000772DOI Listing
September 2015

The predictive value of magnetic resonance imaging in evaluating intracranial arteriovenous malformation obliteration after stereotactic radiosurgery.

J Neurosurg 2015 Jul 3;123(1):136-44. Epub 2015 Apr 3.

Departments of 1 Neurological Surgery.

Object: The current gold standard for diagnosing arteriovenous malformation (AVM) and assessing its obliteration after stereotactic radiosurgery (SRS) is digital subtraction angiography (DSA). Recently, MRI and MR angiography (MRA) have become increasingly popular imaging modalities for the follow-up of patients with an AVM because of their convenient setup and noninvasiveness. In this study, the authors assessed the sensitivity and specificity of MRI/MRA in evaluating AVM nidus obliteration as assessed by DSA.

Methods: The authors study a consecutive series of 136 patients who underwent SRS between January 2000 and December 2012 and who underwent regular clinical examinations, several MRI studies, and at least 1 post-SRS DSA follow- up evaluation at the University of Virginia. The average follow-up time was 47.3 months (range 10.1-165.2 months). Two blinded observers were enrolled to interpret the results of MRI/MRA compared with those of DSA. The sensitivity, specificity, positive predictive value, and negative predictive value for the obliteration of AVM were reported.

Results: On the basis of DSA, 73 patients (53.7%) achieved final angiographic obliteration in a median of 28.8 months. The sensitivity (the probability of finding obliteration on MRI/MRA among those for whom complete obliteration was shown on DSA) was 84.9% for one observer (Observer 1) and 76.7% for the other (Observer 2). The specificity was 88.9% and 95.2%, respectively. The false-negative interpretations were significantly related to the presence of draining veins, perinidal edema on T2-weighted images, and the interval between the MRI/MRA and DSA studies.

Conclusions: MRI/MRA predicted AVM obliteration after SRS in most patients and can be used in their follow-up. However, because the specificity of MRI/MRA is not perfect, DSA should still be performed to confirm AVM nidus obliteration after SRS.
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http://dx.doi.org/10.3171/2014.10.JNS141565DOI Listing
July 2015

Cerebral Arteriovenous Malformations and Epilepsy, Part 1: Predictors of Seizure Presentation.

World Neurosurg 2015 Sep 6;84(3):645-52. Epub 2015 Mar 6.

Department of Neurological Surgery, University of Virginia, Charlottesville, VA, USA. Electronic address:

Objective: Seizures are relatively common in patients harboring cerebral arteriovenous malformations (AVMs). Because the pathogenesis of AVM-associated epilepsy is not well-defined, we aim to determine the factors associated with seizure presentation in AVM patients.

Methods: We evaluated our institutional AVM radiosurgery database, from 1989-2013, to select patients in whom pertinent clinical information at presentation and adequate clinical and radiologic follow-up was available. Baseline patient demographics and AVM angioarchitectural features were compared between patients with and without seizure presentation. In addition to standard descriptive statistics, logistic regression analyses were performed to identify predictors of seizure presentation.

Results: Of the 1007 AVM patients included for analysis, 229 patients presented with seizures (22.7%). The incidence of seizure presentation was significantly higher in cortical than noncortical AVMs (33.1% vs. 6.6%, P < 0.0001). Among the cortical locations, occipital AVMs had the lowest rate of seizure presentation (21.5%, P = 0.0012), whereas the rates of seizure presentation in frontal (37.3%), temporal (37.7%), and parietal (34.0%) AVMs were similar. The lack of prior AVM hemorrhage (P < 0.0001), larger nidus diameter (P < 0.0001), and cortical location (P < 0.0001) were independent predictors of seizure presentation in the multivariate analysis. The strongest independent predictors of seizure presentation were lack of prior AVM hemorrhage (OR 16.8) and cortical location (OR 4.2).

Conclusions: Large, unruptured, cortical nidi are most prone to seizure presentation in patients referred for radiosurgery. Further investigations of the molecular biology, neuronal and glial physiology, and natural history of AVM-associated epilepsy appear warranted.
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http://dx.doi.org/10.1016/j.wneu.2015.02.039DOI Listing
September 2015

Stereotactic radiosurgery for arteriovenous malformations after Onyx embolization: a case-control study.

J Neurosurg 2015 Jul 6;123(1):126-35. Epub 2015 Feb 6.

Departments of 1 Neurological Surgery, and.

Object: Onyx, an ethylene-vinyl alcohol copolymer mixed in a dimethyl sulfoxide solvent, is currently one of the most widely used liquid materials for embolization of intracranial arteriovenous malformations (AVMs). The goal of this study was to define the risks and benefits of stereotactic radiosurgery (SRS) for patients who have previously undergone partial AVM embolization with Onyx.

Methods: Among a consecutive series of 199 patients who underwent SRS between January 2007 and December 2012 at the University of Virginia, 25 patients had Onyx embolization prior to SRS (the embolization group). To analyze the obliteration rates and complications, 50 patients who underwent SRS without prior embolization (the no-embolization group) were matched by propensity score method. The matched variables included age, sex, nidus volume before SRS, margin dose, Spetzler-Martin grade, Virginia Radiosurgery AVM Scale score, and median imaging follow-up period.

Results: After Onyx embolization, 18 AVMs were reduced in size. Total obliteration was achieved in 6 cases (24%) at a median of 27.5 months after SRS. In the no-embolization group, total obliteration was achieved in 20 patients (40%) at a median of 22.4 months after SRS. Kaplan-Meier analysis demonstrated obliteration rates of 17.7% and 34.1% in the embolization group at 2 and 4 years, respectively. In the no-embolization group, the corresponding obliteration rates were 27.0% and 55.9%. The between-groups difference in obliteration rates after SRS did not achieve statistical significance. The difference in complications, including adverse radiation effects, hemorrhage episodes, seizure control, and patient mortality also did not reach statistical significance.

Conclusions: Onyx embolization can effectively reduce the size of many AVMs. This case-control study did not show any statistically significant difference in the rates of embolization or complications after SRS in patients who had previously undergone Onyx embolization and those who had not.
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http://dx.doi.org/10.3171/2014.12.JNS141437DOI Listing
July 2015