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140


Rapid, label-free detection of brain tumors with stimulated Raman scattering microscopy

Ji, Minbiao; Orringer, Daniel A; Freudiger, Christian W; Ramkissoon, Shakti; Liu, Xiaohui; Lau, Darryl; Golby, Alexandra J; Norton, Isaiah; Hayashi, Marika; Agar, Nathalie Y R; Young, Geoffrey S; Spino, Cathie; Santagata, Sandro; Camelo-Piragua, Sandra; Ligon, Keith L; Sagher, Oren; Xie, X Sunney
Surgery is an essential component in the treatment of brain tumors. However, delineating tumor from normal brain remains a major challenge. We describe the use of stimulated Raman scattering (SRS) microscopy for differentiating healthy human and mouse brain tissue from tumor-infiltrated brain based on histoarchitectural and biochemical differences. Unlike traditional histopathology, SRS is a label-free technique that can be rapidly performed in situ. SRS microscopy was able to differentiate tumor from nonneoplastic tissue in an infiltrative human glioblastoma xenograft mouse model based on their different Raman spectra. We further demonstrated a correlation between SRS and hematoxylin and eosin microscopy for detection of glioma infiltration (κ = 0.98). Finally, we applied SRS microscopy in vivo in mice during surgery to reveal tumor margins that were undetectable under standard operative conditions. By providing rapid intraoperative assessment of brain tissue, SRS microscopy may ultimately improve the safety and accuracy of surgeries where tumor boundaries are visually indistinct.
PMID: 24005159
ISSN: 1946-6242
CID: 3927472

Metastatic paraganglioma of the spine: case report and review of the literature [Case Report]

Lau, Darryl; La Marca, Frank; Camelo-Piragua, Sandra; Park, Paul
Paragangliomas are relatively rare tumors, accounting for only about 0.3% of all neoplasms. Most paragangliomas are defined as benign in nature, but 10-20% possess metastatic potential. There have been scattered reports of metastatic paraganglioma in the literature, but in rare circumstances, paragangliomas can metastasize to the spinal column causing destruction or compression of the spinal cord, clinically manifesting as pain or neurological deficit. We report a case of metastatic paraganglioma in which a 47-year-old man had spinal metastasis from a primary abdominal paraganglioma and was found to be positive for SDHB mutation, portraying negative implications for prognosis. Long-term follow-up is reported. In addition, we review the literature on the topic of metastatic paraganglioma, management of paragangliomas involving spine, and touch on the importance of the presence of SDHB mutations in these cases.
PMID: 23398849
ISSN: 1872-6968
CID: 4617922

Comparison of perioperative outcomes following open versus minimally invasive transforaminal lumbar interbody fusion in obese patients

Lau, Darryl; Khan, Adam; Terman, Samuel W; Yee, Timothy; La Marca, Frank; Park, Paul
OBJECT/OBJECTIVE:Minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) has proven to be effective in the treatment of spondylolisthesis and degenerative disc disease (DDD). Compared with the traditional open TLIF, the MI procedure has been associated with less blood loss, less postoperative pain, and a shorter hospital stay. However, it is uncertain whether the advantages of an MI TLIF also apply specifically to obese patients. This study was dedicated to evaluating whether obese patients reap the perioperative benefits similar to those seen in patients with normal body mass index (BMI) when undergoing MI TLIF. METHODS:Obese patients-that is, those with a BMI of at least 30 kg/m(2)-who had undergone single-level TLIF were retrospectively identified and categorized according to BMI: Class I obesity, BMI 30.0-34.9 kg/m(2); Class II obesity, BMI 35.0-39.9 kg/m(2); or Class III obesity, BMI ≥ 40.0 kg/m(2). In each obesity class, patients were stratified by TLIF approach, that is, open versus MI. Perioperative outcomes, including intraoperative estimated blood loss (EBL), complications (overall, intraoperative, and 30-day postoperative), and hospital length of stay (LOS), were compared. The chi-square test, Fisher exact test, or 2-tailed Student t-test were used when appropriate. RESULTS:One hundred twenty-seven patients were included in the final analysis; 49 underwent open TLIF and 78 underwent MI TLIF. Sixty-one patients had Class I obesity (23 open and 38 MI TLIF); 45 patients, Class II (19 open and 26 MI); and 21 patients, Class III (7 open and 14 MI). Overall, mean EBL was 397.2 ml and mean hospital LOS was 3.7 days. Minimally invasive TLIF was associated with significantly less EBL and a shorter hospital stay than open TLIF when all patients were evaluated as a single cohort and within individual obesity classes. Overall, the complication rate was 18.1%. Minimally invasive TLIF was associated with a significantly lower total complication rate (11.5% MI vs 28.6% open) and intraoperative complication rate (3.8% MI vs 16.3% open) as compared with open TLIF. When stratified by obesity class, MI TLIF was still associated with lower rates of total and intraoperative complications. This effect was most profound and statistically significant in patients with Class III obesity (42.9% open vs 7.1% MI). CONCLUSIONS:Minimally invasive TLIF offers obese patients perioperative benefits similar to those seen in patients with normal BMI who undergo the same procedure. These benefits include less EBL, a shorter hospital stay, and potentially fewer complications compared with open TLIF. Additional large retrospective studies and randomized prospective studies are needed to verify these findings.
PMID: 23905948
ISSN: 1092-0684
CID: 4617962

Intraoperative neuromonitoring with MEPs and prediction of postoperative neurological deficits in patients undergoing surgery for cervical and cervicothoracic myelopathy

Clark, Aaron J; Ziewacz, John E; Safaee, Michael; Lau, Darryl; Lyon, Russ; Chou, Dean; Weinstein, Philip R; Ames, Christopher P; Clark, John P; Mummaneni, Praveen V
OBJECT/OBJECTIVE:The use of intraoperative neurophysiological monitoring (IONM) in surgical decompression surgery for myelopathy may assist the surgeon in taking corrective measures to reduce or prevent permanent neurological deficits. We evaluated the efficacy of IONM in cervical and cervicothoracic spondylotic myelopathy (CSM) cases. METHODS:The authors retrospectively reviewed 140 cases involving patients who underwent surgery for CSM utilizing IONM during 2011 at the University of California, San Francisco. Data on preoperative clinical variables, intraoperative changes in transcranial motor evoked potentials (MEPs), and postoperative new neurological deficits were collected. Associations between categorical variables were analyzed with the Fisher exact test. RESULTS:Of the 140 patients, 16 (11%) had significant intraoperative decreases in MEPs. In 8 of these cases, the MEP signal did not return to baseline values by the end of the operation. There were 8 (6%) postoperative deficits, of which 6 were C-5 palsies and 2 were paraparesis. Six of the patients with postoperative deficits had demonstrated persistent MEP signal change on IONM. There was a significant association between persistent MEP changes and postoperative deficits (p < 0.001). The sensitivity of intraoperative MEP monitoring was 75%, the specificity 98%, the positive predictive value 75%, and the negative predictive value 98%. Due to higher rates of false negatives, the sensitivity decreased to 60% in the subgroup of patients with vascular disease comorbidity. The sensitivity increased to 100% in elderly patients and in patients with preoperative motor deficits. The sensitivity and positive predictive value of deltoid and biceps MEP changes in predicting C-5 palsy were 67% and 67%, respectively. CONCLUSIONS:The authors found a correlation between decreased intraoperative MEPs and postoperative new neurological deficits in patients with CSM. Sensitivity varies based on patient comorbidities, age, and preoperative neurological function. Monitoring of MEPs is a useful adjunct for CSM cases, and the authors have developed a checklist to standardize their responses to intraoperative MEP changes.
PMID: 23815252
ISSN: 1092-0684
CID: 4617952

Independent predictors of complication following surgery for spinal metastasis

Lau, Darryl; Leach, Matthew R; Than, Khoi D; Ziewacz, John; La Marca, Frank; Park, Paul
PURPOSE/OBJECTIVE:Surgery for spinal metastasis is often associated with significant morbidity. Despite a number of preoperative scoring systems/scales and identified variables that have been reported to predict complication risk, clinical studies that directly evaluate this issue using multivariate analysis are scarce. The goal of our study was to assess independent predictors of complication after surgery for spinal metastasis. METHODS:We queried electronic medical records to identify a consecutive population of adult patients who underwent surgery for spinal metastasis for the period June 2005 through June 2011. Utilizing multivariate logistic regression, we assessed independent predictors of perioperative and postoperative adverse events. RESULTS:A total of 106 patients were included in the final analysis. Overall complication rate was 21.7 %. Independent predictors for higher rates of complication were age greater than 40 years [40-65 years had odds ratio (OR) 1.91, 95 % confidence interval (CI) 1.02-16.78 and >65 years had OR 5.17, 95 % CI 1.54-29.81] and metastatic lesions involving three or more contiguous levels of the spine (OR 2.76, 95 % CI 1.09-9.61). CONCLUSIONS:Patients older than 40 years or patients who have metastatic lesions involving three or more contiguous vertebral levels appear to be at higher risk for complication. Patients older than 65 years have the greatest likelihood of complication.
PMCID:3676566
PMID: 23392558
ISSN: 1432-0932
CID: 4617902

Radiological outcomes of static vs expandable titanium cages after corpectomy: a retrospective cohort analysis of subsidence

Lau, Darryl; Song, Yeohan; Guan, Zhe; La Marca, Frank; Park, Paul
BACKGROUND:Mesh cages have commonly been used for reconstruction after corpectomy. Recently, expandable cages have become a popular alternative. Regardless of cage type, subsidence is a concern following cage placement. OBJECTIVE:To assess whether subsidence rates differ between static and expandable cages, and identify independent risk factors for subsidence and extent of subsidence when present. METHODS:A consecutive population of patients who underwent corpectomy between 2006 and 2009 was identified. Subsidence was assessed via x-ray at 1-month and 1-year follow-ups. In addition to cage type, demographic, medical, and cage-related covariates were recorded. Multivariate models were used to assess independent associations with rate, odds, and extent of subsidence. RESULTS:Of 91 patients, 44.0% had expandable cages and 56.0% had static cages. One-month subsidence rate was 36.3%, and the 1-year subsidence rate was 51.6%. Expandable cages were independently associated with higher rates and odds of subsidence in comparison with static cages. Infection, trauma, and footplate-to-vertebral body endplate ratio of less than 0.5 were independent risk factors for subsidence. The presence of prongs on cages and posterior fusion 2 or more levels above and below corpectomy level had lower rates and odds of subsidence. Infection and cage placement in the thoracic or lumbar region had greater extent of subsidence when subsidence was present. CONCLUSION/CONCLUSIONS:Expandable cages had higher rates and risk of subsidence in comparison with static cages. When subsidence was present, expandable cages had greater magnitudes of subsidence. Other factors including footplate-to-vertebral body endplate ratio, prongs, extent of supplemental posterior fusion, spinal region, and diagnosis also impacted subsidence.
PMID: 23246824
ISSN: 1524-4040
CID: 4617892

Incidence of and risk factors for superior facet violation in minimally invasive versus open pedicle screw placement during transforaminal lumbar interbody fusion: a comparative analysis

Lau, Darryl; Terman, Samuel W; Patel, Rakesh; La Marca, Frank; Park, Paul
OBJECT/OBJECTIVE:A reported risk factor for adjacent-segment disease is injury to the superior facet joint from pedicle screw placement. Given that the facet joint is not typically visualized during percutaneous pedicle screw insertion, there is a concern for increased facet violation (FV) in minimally invasive fusion procedures. The purpose of this study was to analyze and compare the incidence of FV among patients undergoing minimally invasive transforaminal lumbar interbody fusion (MITLIF) and open transforaminal lumbar interbody fusion (TLIF). The impact of O-arm navigation compared with traditional fluoroscopy on FV in MITLIF is also assessed, as are risk factors for FV. METHODS:The authors identified a consecutive population of patients who underwent MITLIF with percutaneous pedicle screw placement, as well as a matched cohort of patients who underwent open TLIF. Postoperative CT imaging was assessed to determine intraarticular FV due to pedicle screw placement. Patients were stratified into minimally invasive and open TLIF groups. Within the MITLIF group, the authors performed a subanalysis of image guidance methods used in cases of FV. Two-tailed Student t-test, ANOVA, chi-square testing, and logistic regression were used for statistical analysis. RESULTS:A total of 282 patients were identified, with a total of 564 superior pedicle screw placements. The MITLIF group consisted of 142 patients with 284 screw insertions. The open TLIF group consisted of 140 patients with 280 screw insertions. Overall, 21 (7.4%) of 282 patients experienced FV. A total of 21 screws violated a facet joint for a screw-based FV rate of 3.7% (21 of 564 screws). There were no significant differences between the MITLIF and open TLIF groups in the percentage of patients with FV (6.3% vs 8.6%) and or the percentage of screws with FV (3.2% vs 4.3%) (p = 0.475 and p = 0.484, respectively). Further stratifying the MI group into O-arm navigation and fluoroscopic guidance subgroups, the patient-based rates of FV were 10.8% (4 of 37 patients) and 4.8% (5 of 105 patients), respectively, and the screw-based rates of FV were 5.4% (4 of 74 screws) and 2.4% (5 of 210 screws), respectively. There was no significant difference between the subgroups with respect to patient-based or screw-based FV rates (p = 0.375 and p = 0.442, respectively). The O-arm group had a significantly higher body mass index (BMI) (p = 0.021). BMI greater than 29.9 was independently associated with higher FV (OR 2.36, 95% CI 1.65-8.53, p = 0.039). CONCLUSIONS:The findings suggest that minimally invasive pedicle screw placement is not associated with higher rates of FV. Overall violation rates were similar in MITLIF and open TLIF. Higher BMI, however, was a risk factor for increased FV. The use of O-arm fluoroscopy with computer-assisted guidance did not significantly decrease the rate of FV.
PMID: 23394166
ISSN: 1547-5646
CID: 4617912

Perioperative characteristics, complications, and outcomes of single-level versus multilevel thoracic corpectomies via modified costotransversectomy approach

Lau, Darryl; Song, Yeohan; Guan, Zhe; Sullivan, Stephen; La Marca, Frank; Park, Paul
STUDY DESIGN/METHODS:Retrospective case series. OBJECTIVE:To compare perioperative end points and outcomes of single-level versus multilevel corpectomy performed using a modified costotransversectomy approach. SUMMARY OF BACKGROUND DATA/BACKGROUND:Single-level corpectomy via posterolateral approach has been shown to be an effective alternative to the traditional anterior thoracotomy approach. However, there is a paucity of studies that have examined multilevel thoracic corpectomy via posterolateral approach. METHODS:Using electronic medical records, we identified a consecutive population of adult patients who underwent modified costotransversectomy corpectomy in the thoracic region between 2006 and 2009. Patients were stratified by number of corpectomies performed into either a single-level or multilevel group. With the use of baseline descriptive statistics and multivariate analysis, perioperative parameters and follow-up outcomes were assessed between the 2 groups. RESULTS:A total of 40 patients were included in the final analysis, with 25 patients in the single-level group and 15 patients in the multilevel group. Mean follow-up was 16.1 months. Overall complication rate was 37.5%. Between the 2 groups, there were no significant differences in operative time, blood loss, transfusion rate, quantity of blood transfused, length of hospital stay, or complication rates. Also, there were no significant differences in repeat surgery rate, Medical Research Council strength, Nurick score, or pain at most recent follow-up, and all groups gained a comparable magnitude of benefit from surgery. CONCLUSION/CONCLUSIONS:Multilevel corpectomy via modified costotransversectomy approach in the thoracic region is a feasible and effective option that does not seem to be associated with significantly increased morbidity. The degree of clinical improvement also seems comparable with single-level corpectomy.
PMID: 22986841
ISSN: 1528-1159
CID: 4617842

Validation of the surgical Apgar score in a neurosurgical patient population

Ziewacz, John E; Davis, Matthew C; Lau, Darryl; El-Sayed, Abdulrahman M; Regenbogen, Scott E; Sullivan, Stephen E; Mashour, George A
OBJECT/OBJECTIVE:The surgical Apgar score (SAS) reliably predicts postoperative death and complications and has been validated in a large cohort of general and vascular surgery patients. However, there has been limited study of the utility of the score in the neurosurgical population. The authors tested the hypothesis that the SAS would predict postoperative complications and length of stay after neurosurgical procedures. METHODS:A cohort of 918 intracranial and spine surgery patients treated over a 3-year period were retrospectively evaluated. The 10-point SAS was calculated and postoperative 30-day mortality and complications rates, intensive care unit (ICU) stay, and hospital stay were assessed by 2 independent raters. Univariate analysis and multivariate logistic regression were performed. RESULTS:There were 145 patients (15.8%) with at least 1 complication and 24 patients (2.6%) who died within 30 days of surgery. Surgical Apgar scores were significantly associated with the likelihood of postoperative complications (p < 0.001) and death (p = 0.002); scores varied inversely with postoperative complication and mortality risk in a multivariate analysis. Low SASs also predicted prolonged ICU and hospital stay. Patients with scores of 0-2 stayed a mean of 18.9 days (p < 0.001) and patients with scores of 3-4 stayed an average of 14.3 days (p < 0.001) compared with 4.1 days in patients with scores of 9-10. CONCLUSIONS:The application of the surgical Apgar score to a neurosurgical cohort predicted 30-day postoperative mortality and complication rates as well as extended ICU and hospital stay. This readily calculated score may help neurosurgical teams efficiently direct postoperative care to those at highest risk of death and complications.
PMID: 23121434
ISSN: 1933-0693
CID: 4617872

Minimally invasive transforaminal lumbar interbody fusion for spondylolisthesis in patients with significant obesity

Lau, Darryl; Ziewacz, John; Park, Paul
Comparative studies evaluating efficacy and safety of minimally invasive spinal fusion between patients with significant obesity (body mass index [BMI]≥35 kg/m(2)) and those of normal weight are scarce. We examined complication rates and outcomes for minimally invasive transforaminal lumbar interbody fusion (MITLIF) in patients with significant obesity and those of normal weight undergoing treatment for symptomatic spondylolisthesis. Patients with a BMI≥35 kg/m(2) or <25 kg/m(2) undergoing elective MITLIF for symptomatic spondylolisthesis for the period 2006-09 were identified. Of the 16 patients identified, nine patients with a mean BMI of 37.4 kg/m(2) were included in the obese group, while seven patients with a mean BMI of 23.4 kg/m(2) comprised the normal weight group. Estimated blood loss (EBL), operative time, complication rate, length of hospital stay, and clinical outcomes were assessed. Outcome measures included patient-reported visual analog scale (VAS) score for pain and the Oswestry Disability Index (ODI) questionnaire completed by the patient. No significant differences were found in blood loss (p=0.436), hospital stay (p=0.606), or number of surgical complications (p=0.920) between the two groups. Mean follow-up intervals were 15.0 months for patients with obesity, and 18.6 months for those of normal weight. Both groups had significant improvements in VAS (obese, p=0.003; normal, p=0.016) and ODI (obese, p=0.020; normal, p=0.034) scores. There were no statistically significant differences between normal weight and obese groups in postoperative VAS (p=0.728) and ODI (p=0.886) scores. Patients with significant obesity experienced clinical improvement similar to that of patients with normal weight, suggesting that obesity does not impact MITLIF outcomes. In addition, both groups experienced similar complication rates, operative times, EBL, and length of hospital stay.
PMID: 23047060
ISSN: 1532-2653
CID: 4617862