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Rajiv Saigal, Daniel C. Lu, Donna Y. Deng and Dean Chou

Chordomas of the sacrum require en bloc resection to reduce the risk of recurrence, but this may sacrifice nerves vital to bladder, bowel, and sexual function. High, mid-, and low sacral amputations have been previously classified based on nerve root sacrifice, not bony amputation. Sacrifice of the S-2 nerves or those above results in a high sacral amputation, but preserving the S-2 nerves converts it into a midsacral amputation. Preservation of the S-2 nerves has been shown to improve functional outcome, despite the bony osteotomy being unchanged. Thus, keeping the same bony amputation while preserving the S-2 nerve roots may allow for improved functional outcome while still achieving the same goal of oncological resection. Preservation of the S-2 nerves may be particularly difficult during amputation at the S-2 pedicle or above, and the authors describe their technique for preserving the S-2 nerves during partial sacrectomy at or just above the S-2 pedicle. Four cases of sacral chordoma resections are presented to illustrate 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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Daniel C. Lu, Dean Chou and Praveen V. Mummaneni

Object

Standard approaches to thoracic intradural tumors often involve a large incision and significant tissue destruction. Minimally invasive techniques have been applied successfully for a variety of surgical decompression procedures but have been rarely used for the removal of intradural thoracolumbar tumors. In this paper, the authors compare the clinical outcome of mini-open resection of intradural thoracolumbar tumors with a standard open technique.

Methods

The authors retrospectively reviewed their series of 18 consecutive mini-open thoracolumbar, intradural, tumor resection cases and compared the outcomes with a profile-matched cohort of 9 cases of open intradural tumor resection. Operative statistics, functional outcome, and complications were compared.

Results

Tumors were removed successfully using both approaches, except for 1 case in the mini-open cohort in which only biopsy was performed for a diffusely infiltrating tumor (glioblastoma). There was no statistically significant difference in operative duration, American Spinal Injury Association scale score improvement, or back pain visual analog scale score improvement between groups. However, the mini-open group demonstrated a significantly lower estimated blood loss (153 vs 372 ml, respectively) and a significantly shorter length of hospitalization (4.9 vs 8.2 days, respectively). There was 1 complication of pseudomeningocele formation in the mini-open cohort and 1 complication of cerebral infarction in the open cohort. Mean follow-up length was 16 months in the mini-open group compared with 20 months in the open group.

Conclusions

The mini-open approach allows for adequate treatment of intradural thoracolumbar tumors with comparable outcomes to standard, open approaches. The mini-open approach is associated with less blood loss and a shorter length of stay compared with standard open surgery.

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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, Darryl Lau, Jasmine G. Lee and Dean Chou

Object

Whereas standard anterior approaches for thoracolumbar corpectomies have commonly been used, the transpedicular technique is increasingly used to perform corpectomies from a posterior approach. The authors conducted a study to analyze whether there was a difference in outcomes by comparing transpedicular corpectomies to standard anterior thoracolumbar corpectomies.

Methods

The senior author performed thoracolumbar corpectomies in 80 patients between 2004 and 2008. The authors reviewed medical records and follow-up data, consisting of clinic visits, radiographs, or telephone interviews. Neurological outcome, complications, operative times, revision surgery rates, and estimated blood loss (EBL) were evaluated.

Results

Thirty-four patients underwent transpedicular corpectomies, and 46 patients underwent anterior thoracolumbar approaches. Single-level transpedicular corpectomies appear to be comparable to anterior-only corpectomies in terms of EBL, operative time, and complication rates. There was a higher complication rate, increased EBL, and longer operative time with anterior-posterior corpectomies compared with transpedicular corpectomies. Patients undergoing transpedicular corpectomies had a greater recovery of neurological function than those in whom anterior-approach corpectomies were performed.

Conclusions

The transpedicular corpectomy appears to have a comparable morbidity rate to anterior-only corpectomies, but its morbidity rate is lower than that of anterior-posterior corpectomies.

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Dean Chou, Daniel C. Lu, Philip Weinstein and Christopher P. Ames

✓Expandable cages are frequently used to reconstruct the anterior spinal column after a corpectomy. The forces that are used to expand these cages can be large, depending upon the mechanism of expansion. To the authors' knowledge, there have been no reports of adjacent-level vertebral body fracture after placement of expandable cages. The authors report 4 cases of adjacent-level vertebral body fractures after placement of expandable cages. This study found that the fracture pattern in the coronal plane was similar in all cases.