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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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Andrew Yew, Jon Kimball and Daniel C. Lu

Seroma formation following posterior cervical laminectomy and fusion is now recognized as a rare but significant risk. Previous reports have attributed the development of postoperative seromas to the use of recombinant bone morphogenetic protein–2 (rhBMP-2). Here the authors present the case of a 78-year-old female with a history of osteoporosis who developed delayed postoperative neck and shoulder pain following posterior cervical laminectomy and fusion utilizing only autograft bone and demineralized bone matrix (DBM) allograft. Postoperative MRI demonstrated normal hardware placement and a large epidural fluid collection that extended from C-4 to C-6. The patient underwent decompression and drainage of her sterile postoperative seroma. To the authors' knowledge, no case of seroma formation with the use of DBM has been previously reported. This case suggests that although rhBMP-2 is involved in the majority of postoperative seroma developments, other osteoinductive agents such as DBM can contribute to the development of a symptomatic seroma. This report presents an illustrative case study and reviews the current understanding of the development of and treatment for cervical seroma following posterior cervical laminectomy and fusion.

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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 and Michael T. Lawton

Object

Intramedullary cavernous malformation (CM) is a rare entity, accounting for 5% of all intraspinal lesions. The objective in this study was to define the clinical characteristics of this disease, detail the surgical approach and technique, and present the clinical outcome.

Methods

Retrospective chart review was performed in 22 patients with histologically confirmed CMs. The authors used a laminectomy approach for midline dorsal lesions, with unilateral radical facetectomy and dentate ligament resection for laterally or ventrally located lesions. Patient profiles, operative indications, surgical approaches, operative findings, complications, and long-term follow-up were reviewed.

Results

The average age of patients in the cohort was 43 ± 14 years, the average duration of symptoms was 7 ± 7 months, and the average follow-up was 6 ± 4 years. The average size of the lesion was 1 ± 0.4 cm, the average surgical time was 4 ± 0.96 hours, and the average estimated blood loss was 350 ± 131 ml. The rate of complication was 5% (1 patient; due to a wound infection). According to the McCormick classification, the score for the cohort was 1.8 ± 1.2 preoperatively, 2.1 ± 1.2 postoperatively, and 1.3 ± 0.65 at late follow-up. (All preceding values are given as the mean ± SD.) There was a significant neurological improvement at follow-up compared with the preoperative state (p < 0.05). The majority of patients (50%) had a stable outcome compared with their preoperative state, with a large proportion (41%) having an improved outcome. A minority of patients (9%) had a worsened outcome due to dysesthetic pain. Patients with dysesthesia had a longer duration of clinical symptoms prior to surgery compared with patients without dysesthesia (p < 0.05).

Conclusions

The authors demonstrated the safety, efficacy, and durability of their surgical approach for resection of spinal intramedullary CM. Proper examination, preoperative imaging, and prompt surgical intervention were necessary for a satisfactory outcome.

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Jon Kimball, Andrew Yew and Daniel C. Lu

Symptomatic disc herniation is a common indication for spinal operations. The open microscopic discectomy has been the traditional method of addressing this pathology, but minimally invasive techniques are increasingly popular.

Potential advantages of the MIS microdiscectomy approach include decreased muscle and soft tissue disruption, shorter length of stay and decreased postoperative pain. Here we demonstrate an MIS microdiscectomy on a 24-year-old female with a left L-4 and L-5 radiculopathy secondary to a large L4–5 disc herniation.

The video can be found here: http://youtu.be/aXyZ2FJMh2s.

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Daniel C. Lu and Peter P. Sun

✓The authors describe the use of bone morphogenetic protein (BMP) to promote bone fusion in an infant with craniovertebral instability after two attempts at arthrodesis had failed. To their knowledge, this is the first such report. Management of craniovertebral instability remains challenging in infants with Down syndrome. Surgical treatment may result in nonunion in this patient population. The authors report on a 4-month-old boy with Down syndrome who suffered a high cervical spinal cord injury secondary to craniovertebral instability. Two attempts to fuse and stabilize the craniovertebral junction resulted in nonunion. Finally, the use of BMP led to a stable fusion construct within 6 months without encroachment on the spinal canal. At 4 years of follow up, the patient has a solid fusion mass. The case suggests a role for the use of BMP to promote fusion in this patient population.

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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.

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Jon Kimball, Andrew Yew, Ruth Getachew and Daniel C. Lu

Transforaminal lumbar interbody fusion (TLIF) was originally developed as a method for circumferential fusion via a single posterior approach and is now an extremely common procedure for the treatment of lumbar instability. More recently, minimally invasive techniques have been applied to this procedure with the goal of decreasing tissue disruption, blood loss and postoperative patient discomfort. Here we describe a minimally invasive tubular TLIF on a 60-year-old male with radiculopathy from an unstable L4–5 spondylolisthesis.

The video can be found here: http://youtu.be/0BbxQiUmtRc.

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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.