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Darryl Lau and Dean Chou

OBJECT

Spinal metastases most commonly affect the vertebral bodies of the spinal column, and spinal cord compression is an indication for surgery. Commonly, an open posterior approach is employed to perform a transpedicular costotransversectomy or lateral extracavitary corpectomy. Because of the short life expectancies in patients with metastatic spinal disease, decreasing the morbidity of surgical treatment and recovery time is critical. One potential approach to decreasing morbidity is utilizing minimally invasive surgery (MIS). Although significant advances have been made in MIS of the spine, data supporting the utility of MIS are still emerging. This study compared outcomes of patients who underwent mini-open versus traditional open transpedicular corpectomy for spinal metastases in the thoracic spine.

METHODS

A consecutive cohort from 2006 to 2013 of 49 adult patients who underwent thoracic transpedicular corpectomies for spinal metastases was retrospectively identified. Patients were categorized into one of 2 groups: open surgery and mini-open surgery. Mini-open transpedicular corpectomy was performed with a midline facial incision over only the corpectomy level of interest and percutaneous instrumentation above and below that level. The open procedure consisted of a traditional posterior transpedicular corpectomy. Chi-square test, 2-tailed t-test, and ANOVA models were employed to compare perioperative and follow-up outcomes between the 2 groups.

RESULTS

In the analysis, there were 21 patients who had mini-open surgery and 28 patients who had open surgery. The mean age was 57.9 years, and 59.2% were male. The tumor types encountered were lung (18.3%), renal/bladder (16.3%), breast (14.3%), hematological (14.3%), gastrointestinal tract (10.2%), prostate (8.2%), melanoma (4.1%), and other/unknown (14.3%). There were no significant intergroup differences in demographics, comorbidities, neurological status (American Spinal Injury Association [ASIA] grade), number of corpectomies performed, and number of levels instrumented. The open group had a mean operative time of 413.6 minutes, and the mini-open group had a mean operative time of 452.4 minutes (p = 0.329). Compared with the open group, the mini-open group had significantly less blood loss (917.7 ml vs 1697.3 ml, p = 0.019) and a significantly shorter hospital stay (7.4 days vs 11.4 days, p = 0.001). There was a trend toward a lower perioperative complication rate in the mini-open group (9.5%) compared with the open group (21.4%), but this was not statistically significant (p = 0.265). At follow-up, there were no significant differences in ASIA grade (p = 0.342), complication rate after the 30-day postoperative period (p = 0.999), or need for surgical revision (p = 0.803). The open approach had a higher overall infection rate of 17.9% compared with that in the mini-open approach of 9.5%, but this was not statistically significant (p = 0.409).

CONCLUSIONS

The mini-open transpedicular corpectomy is associated with less blood loss and shorter hospital stay compared with open transpedicular corpectomy. The mini-open corpectomy also trended toward lower infection and complication rates, but these did not reach statistical significance.

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Darryl Lau and Dean Chou

OBJECTIVE

During the mini-open posterior corpectomy, percutaneous instrumentation without fusion is performed above and below the corpectomy level. In this study, the authors' goal was to compare the perioperative and long-term implant failure rates of patients who underwent nonfused percutaneous instrumentation with those of patients who underwent traditional open instrumented fusion.

METHODS

Adult patients who underwent posterior thoracic corpectomies with cage reconstruction between 2009 and 2014 were identified. Patients who underwent mini-open corpectomy had percutaneous instrumentation without fusion, and patients who underwent open corpectomy had instrumented fusion above and below the corpectomy site. The authors compared perioperative outcomes and rates of implant failure requiring reoperation between the open (fused) and mini-open (unfused) groups.

RESULTS

A total of 75 patients were identified, and 53 patients (32 open and 21 mini-open) were available for followup. The mean patient age was 52.8 years, and 56.6% of patients were male. There were no significant differences in baseline variables between the 2 groups. The overall perioperative complication rate was 15.1%, and there was no significant difference between the open and mini-open groups (18.8% vs 9.5%; p = 0.359). The mean hospital stay was 10.5 days. The open group required a significantly longer stay than the mini-open group (12.8 vs 7.1 days; p < 0.001). Overall implant failure rates requiring reoperation were 1.9% at 6 months, 9.1% at 1 year, and 14.7% at 2 years. There were no significant differences in reoperation rates between the open and mini-open groups at 6 months (3.1% vs 0.0%, p = 0.413), 1 year (10.7% vs 6.2%, p = 0.620), and 2 years (18.2% vs 8.3%, p = 0.438). The overall mean follow-up was 29.2 months.

CONCLUSIONS

These findings suggest that percutaneous instrumentation without fusion in mini-open transpedicular corpectomies offers similar implant failure and reoperation rates as open instrumented fusion as far out as 2 years of follow-up.

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Darryl Lau, Dean Chou and Praveen V. Mummaneni

OBJECT

In the treatment of cervical spondylotic myelopathy (CSM), anterior cervical corpectomy and fusion (ACCF) and anterior cervical discectomy and fusion (ACDF) are effective decompressive techniques. It remains to be determined whether ACCF and ACDF offer equivalent outcomes for multilevel CSM. In this study, the authors compared perioperative, radiographic, and clinical outcomes between 2-level ACCF and 3-level ACDF.

METHODS

Between 2006 and 2012, all patients at the authors' hospital who underwent 2-level ACCF or 3-level ACDF performed by 1 of 2 surgeons were identified. Primary outcomes of interest were sagittal Cobb angle, adjacent-segment disease (ASD) requiring surgery, neck pain measured by visual analog scale (VAS), and Nurick score. Secondary outcomes of interest included estimated blood loss (EBL), length of stay, perioperative complications, and radiographic pseudarthrosis rate. Chi-square tests and 2-tailed Student t-tests were used to compare the 2 groups. A subgroup analysis of patients without posterior spinal fusion (PSF) was also performed.

RESULTS

Twenty patients underwent 2-level ACCF, and 35 patients underwent 3-level ACDF during a 6-year period. Preoperative Nurick scores were higher in the ACCF group (2.1 vs 1.1, p = 0.014), and more patients underwent PSF in the 2-level ACCF group compared with patients in the 3-level ACDF group (60.0% vs 17.1%, p = 0.001). Otherwise there were no significant differences in demographics, comorbidities, and baseline clinical parameters between the 2 groups. Two-level ACCF was associated with significantly higher EBL compared with 3-level ACDF for the anterior stage of surgery (382.2 ml vs 117.9 ml, p < 0.001). Two-level ACCF was also associated with a longer hospital stay compared with 3-level ACDF (7.2 days vs 4.9 days, p = 0.048), but a subgroup comparison of patients without PSF showed no significant difference in length of stay (3.1 days vs 4.4 days for 2-level ACCF vs 3-level ACDF, respectively; p = 0.267). Similarly, there was a trend toward more complications in the 2-level ACCF group (20.0%) than the 3-level ACDF group (5.7%; p = 0.102), but a subgroup analysis that excluded those who had second-stage PSF no longer showed the same trend (2-level ACCF, 0.0% vs 3-level ACDF, 3.4%; p = 0.594). There were no significant differences between the ACCF group and the ACDF group in terms of postoperative sagittal Cobb angle (7.2° vs 12.1°, p = 0.173), operative ASD (6.3% vs 3.6%, p = 0.682), and radiographic pseudarthrosis rate (6.3% vs 7.1%, p = 0.909). Both groups had similar improvement in mean VAS neck pain scores (3.4 vs 3.2 for ACCF vs ACDF, respectively; p = 0.860) and Nurick scores (0.8 vs 0.7, p = 0.925).

CONCLUSIONS

Two-level ACCF was associated with greater EBL and longer hospital stays when patients underwent a second-stage PSF. However, the length of stay was similar when patients underwent anterior-only decompression with either 2-level ACCF or 3-level ACDF. Furthermore, perioperative complication rates were similar in the 2 groups when patients underwent anterior decompression without PSF. Both groups obtained similar postoperative cervical lordosis, operative ASD rates, radiographic pseudarthrosis rates, neurological improvement, and pain relief.

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Dean Chou and Daniel C. Lu

Transpedicular corpectomies are frequently used to perform anterior surgery from a posterior approach. Minimally invasive thoracolumbar corpectomies have been previously described, but these are performed through a unilateral approach. Bilateral access must be obtained for a circumferential decompression when using such techniques. The authors describe a technique that allows for a mini-open transpedicular corpectomy, 360° decompression, and expandable cage reconstruction through a single posterior approach. This is performed using percutaneous pedicle screws, the trap-door rib-head osteotomy, and a single midline fascial exposure. The authors describe this technique with intraoperative photos and a video demonstrating the technique.

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Daniel C. Lu, Luis M. Tumialán and Dean Chou

Object

Reported complications of recombinant human bone morphogenetic protein–2 (rhBMP-2) use in anterior cervical discectomy and fusion (ACDF) cases include dysphagia and cervical swelling. However, dysphagia often occurs after multilevel ACDF procedures performed with allograft (without BMP) as well. To date, there has been no large study comparing the dysphagia rates of patients who have undergone multilevel ACDF using allograft spacers with those who underwent ACDF using polyetheretherketone (PEEK) cages filled with rhBMP2. The authors report one of the first such comparisons between these 2 patient cohorts.

Methods

The authors retrospectively reviewed 150 patient records. Group 1 (BMP group) consisted of 100 patients who underwent multilevel ACDF with PEEK cages filled with rhBMP-2 and instrumented with a cervical plate. Group 2 (allograft group) included a matched control cohort of 50 patients who underwent multilevel ACDF with allograft spacers and anterior plate fixation (without rhBMP-2). Patient demographics were not significantly different between the groups. Fusion was assessed by means of dynamic radiographs and/or CT at routine intervals. Complications, dysphagia incidence, standardized dysphagia score, Nurick grades, and fusion rates were assessed.

Results

The mean follow-up for the BMP group (Group 1) was 35 months while the mean follow-up for the allograft group (Group 2) was 25 months. There was a complication rate of 13% in the BMP group compared with 8% in the allograft group (p < 0.005). There was no significant difference in overall dysphagia incidence between the BMP group and the allograft group (40% vs 44%, respectively; p > 0.05). However, there was a significant difference in the severity of dysphagia (using the SWAL-QOL dysphagia scoring system) between the 2 groups: 0.757 for the BMP group versus 0.596 for the allograft group (p < 0.005). In subgroup analysis, the use of rhBMP-2 significantly increased the severity of dysphagia in patients undergoing 2-level ACDF (p < 0.005). However, the severity of dysphagia did not differ significantly between groups when 3- or 4-level ACDF cases were compared. There was no pseudarthrosis in Group 1 (the BMP group) compared with a 16% pseudarthrosis rate in Group 2 (the allograft group) (p < 0.05). There was a weak correlation between the total rhBMP-2 dose and the dysphagia score (Kendall tau rank correlation coefficient 0.166, p = 0.046).

Conclusions

The use of rhBMP-2 in patients undergoing 2-level ACDF significantly increases the severity of dysphagia (dysphagia score) without affecting the overall incidence of dysphagia. However, there is no statistically significant difference in the incidence or severity of dysphagia between patients undergoing 3-level or 4-level ACDF treated with PEEK/rhBMP-2 and those treated with only allograft. The use of rhBMP-2 appears to reduce the risk of pseudarthrosis. This benefit is most pronounced in patients who undergo 4-level ACDF and are smokers.

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Kunal P. Raygor, Khoi D. Than, Dean Chou and Praveen V. Mummaneni

OBJECT

Spinal tumor resection has historically been performed via open approaches, although minimally invasive approaches have recently been found to be effective in small cohort series. The authors compare surgical characteristics and clinical outcomes of surgery in patients undergoing mini-open and open approaches for intradural-extramedullary tumor resection.

METHODS

The authors retrospectively reviewed 65 consecutive intradural-extramedullary tumor resections performed at their institution from 2007 to 2014. Patients with cervical tumors or pathology demonstrating neurofibroma were excluded (n = 14). The nonparametric Mann-Whitney U-test and Pearson chi-square test were used to compare continuous and categorical variables, respectively. Statistical analyses were performed using SPSS, with significance set at p < 0.05.

RESULTS

Fifty-one thoracolumbar intradural-extramedullary tumor resections were included; 25 were performed via the minimally invasive transspinous approach. There were no statistically significant differences in age, sex, body mass index, preoperative American Spinal Injury Association (ASIA) score, preoperative symptom duration, American Society of Anesthesiologists (ASA) physical status class, tumor size, or tumor location. There was no statistically significant difference between groups with respect to the duration of the operation or extent of resection, but the mean estimated blood loss was significantly lower in the minimally invasive surgery (MIS) cohort (142 vs 320 ml, p < 0.05). In each group, the 2 most common tumor pathologies were schwannoma and meningioma. There were no statistically significant differences in length of hospitalization, ASIA score improvement, complication rate, or recurrence rate. The mean duration of follow-up was 2 years for the MIS group and 1.6 years for the open surgery group.

CONCLUSIONS

This is one of the largest comparisons of minimally invasive and open approaches to the resection of thoracolumbar intradural-extramedullary tumors. With well-matched cohorts, the minimally invasive transspinous approach appears to be as safe and effective as the open technique, with the advantage of significantly reduced intraoperative blood loss.

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Dean Chou and Vincent Y. Wang

Lateral extracavitary and costotransversectomy approaches have been well described, and they are useful for posterior thoracic corpectomies. However, these approaches require pleural dissection and are associated with welldocumented morbidities, including hemothorax, pneumothorax, and pneumonia. But without removing the rib head, the window through which an expandable cage can be placed from a posterior approach is narrow. Thus, smaller nonexpandable mesh cages or methylmethacrylate constructs are commonly used for anterior column reconstruction. The authors describe a technique of using a “trap-door” rib-head osteotomy that avoids pleural dissection, yet allows a large expandable cage to be placed from an entirely posterior approach.

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Dean Chou, Prakash Sampath and Henry Brem

Hemorrhagic vestibular schwannomas are rare entities, with only a few case reports in the literature during the last 25 years. The authors review the literature on vestibular schwannoma hemorrhage and the presenting symptoms of this entity, which include headache, nausea, vomiting, sudden cranial nerve dysfunction, and ataxia. A very unusual case is presented of a 36-year-old man, who unlike most of the patients reported in the literature, had clinically silent vestibular schwannoma hemorrhage. The authors also discuss the management issues involved in more than 1000 vestibular schwannomas treated at their institution during a 25-year period.

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Laurence A. G. Marshman

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Dean Chou, Phillip B. Storm and James N. Campbell

Object. Autologous bone graft harvesting from the iliac crest remains the gold standard for fusion surgery. One disadvantage of autologous bone harvesting is the patient's enduring postoperative pain at the donor site. Nerve injury is one of the postulated mechanisms that may account for this pain. The object of this study was to determine whether the lateral cutaneous branch of the subcostal nerve is vulnerable to injury in the process of obtaining grafts from the anterior iliac crest.

Methods. Anatomical dissections were performed on 10 cadaveric specimens to ascertain the size of the T-12 subcostal nerve and its position in relation to the iliac crest.

Conclusions. The lateral cutaneous branch of the subcostal nerve may lie as close as 6 cm from the anterior superior iliac spine. This nerve is very vulnerable to injury when harvesting bone from the anterior iliac crest. Knowledge of the anatomy may decrease the risk of injury to this nerve.