Weilin Shang

A new in vivo animal model to create intervertebral disc degeneration characterized by MRI, radiography, CT/discogram, biochemistry, and histology.

Study Design. A new in vivo sheep model was developed that produced disc degeneration through the injection of 5-bromodeoxyuridine (BrdU) into the intervertebral disc. This process was studied using magnetic resonance imaging (MRI), radiography, CT/discogram, histology, and biochemistry. Objectives. To develop a sheep model of intervertebral disc degeneration that more faithfully mimics the pathologic hallmarks of human intervertebral disc degeneration. Summary of Background Data. Recent studies have shown age-related alterations in proteoglycan structure and organization in human intervertebral discs. An animal model that involves the use of age-related changes in disc cells can be beneficial over other more invasive degenerative models that involves directly damaging the matrix of disc tissue. Methods. Twelve sheep were injected with BrdU or vehicle (phosphate-buffered saline) into the central region of separate lumbar discs. Intact discs were used as controls. At the 2-, 6-, 10-, and 14-week time points, discs underwent MRI, radiography, histology, and biochemical analyses. A CT/discogram study was performed at the 14-week time point. Results. MRI demonstrated a progressive loss of T2-weighted signal intensity at BrdU-injected discs over the 14-week study period. Radiograph findings included osteophyte and disc space narrowing formed by 10 weeks post-BrdU treatment. CT discography demonstrated internal disc disruption in several BrdU-treated discs at the 14-week time point. Histology showed a progressive loss of the normal architecture and cell density of discs from the 2-week time point to the 14-week time point. A progressive loss of cell proliferation capacity, water content, and proteoglycans was also documented. Conclusions. BrdU injection into the central region of sheep discs resulted in degeneration of intervertebral discs. This progressive, degenerative process was confirmed using MRI, histology, and by observing changes in biochemistry. Degeneration occurred in a manner that was similar to that observed in human disc degeneration.

The expression of tumor necrosis factor-α and CD68 in high-intensity zone of lumbar intervertebral disc on magnetic resonance image in the patients with low back pain.

Study Design. Several recent studies suggest a high-intensity zone (HIZ) within the posterior annulu of lumbar intervertebral disc seen on T2-weighted magnetic resonance (MR) images represents the inflammation in the annulus, an annular tear, and/or vascular granulation tissue. It has not be reported yet whether there is the expression of tumor necrosis factor (TNF-&agr;) and inflammatory cells appear in HIZ of intervertebral disc on MR images. Objective. To study whether HIZ is a specific signal for the inflammatory reaction of painful intervertebral disc. Summary of Background Data. The presence of HIZ signal within the posterior annulus seen on sagittal T2-weighted spin-echo magnetic imaging sequences has already been used in the diagnosis of painful annular tears in the last decade. There have been studies suggesting that the presence of HIZ reflects inflammation in the annulus, an annular tear, and/or vascular granulation tissue. Methods. Twenty-six consecutive patients with low back pain underwent MR images and discography (age range = 26–65 years; mean age = 47.5 years; 16 men, 10 women). In all the patients, HIZ appeared in the involved intervertebral discs on T2-weighted MR images. Lumbar discography was usually performed on each patient for the discs L3–L4, L4–L5, and L5–S1. All patients received posterior lumbar interbody fusion procedures. The intervertebral disc specimens contained HIZ were excised en bloc during posterior interbody fusion. The distribution of TNF-&agr; and CD68 in the intervertebral disc specimens within HIZ on MR images from 26 consecutive patients with low back pain and in the intervertebral disc specimens from five fresh cadavers were observed. Results. The histologic study of the consecutive sagittal slices of the HIZ showed a lot of proliferated small round cells and fibroblasts. There were a lot of TNF-&agr; positive cells and some CD68 positive cells in HIZ and the number of TNF-&agr; and CD68 positive cells in HIZ was significantly higher than that in the annulus fibrosus around HIZ and in the control (P < 0.05). Conclusion. The results of this study indicate that HIZ may be a specific signal for the inflammatory reaction of painful intervertebral disc.

The strategy and early clinical outcome of full-endoscopic L5/S1 discectomy through interlaminar approach.

OBJECTIVE To analyze the surgical strategy, safety and clinical outcome of full-endoscopic discectomy through interlaminar approach in the case of L5/S1 intervertebral disc excision. METHODS From April 2011 to December 2011, 72 cases of intracanalicular non-contained disc herniations at L5/S1 level were treated with full-endoscopic discectomy through interlaminar approach. L5/S1 disc herniation was divided into three types according to position of herniated disc related to S1 nerve root: axilla type, ventral type and shoulder type. Axilla approach was selected for axilla type while shoulder approach was selected for ventral type and shoulder type. After operation, MRI was reexamined to evaluate the resection completeness of prolapsed disc material. Visual analog scales (VAS) of low back pain and sciatica, and Oswestry disability index (ODI) were recorded in certain preoperative and postoperative time points. MacNab scores were evaluated at the 12-month follow-up. RESULTS All operations were completed without conversion to other surgical techniques. Average operation time was 45 min (20-80 min). Only one reoccurrence was revised with microendoscopic discectomy. No nerve injury and infection were complicated. Postoperative ODI and VAS of low back pain and sciatica were significantly decreased in each time point (P < 0.05). MacNab scores of 12-month follow-up include 44 excellent, 26 good, 1 fair and 1 poor. CONCLUSION With proper selection between axilla approach and shoulder approach according to the sites of prolapsed or sequestered disc materials, full-endoscopic L5/S1 discectomy through interlaminar approach is a safe, rational and effective minimally invasive spine surgery technique with excellent clinical short-term outcomes.

Cervical myelopathy caused by anomalies at the level of atlas.

Study Design. Case report. Objective. To report a case of cervical myelopathy due to simultanous anomalies at the level of atlas involving hypoplasia of the posterior arch of the atlas, partial ossification of the transverse atlantal ligament, and hypertrophy of the dens. Summary of Background Data. Hypoplasia of the posterior arch of the atlas, ossification of the transverse atlantal ligament, and hypertropthy of the dens are all individually very rare clinical entities. We are not aware of previous reports describing the association of hypoplasia of the posterior arch of the atlas, partial ossification of the transverse atlantal ligament, and hypertrophy of the dens. Methods. The patients medical history, physical examination, and radiographic evaluation are examined. Surgical treatment and clinical outcome are reported. In addition, available literature is also reviewed. Results. The patients neurologic symptoms significantly improved after posterior decompressive surgery. Conclusion. We believe this is the first case of cervical myelopathy caused by simultaneous anomalies at the level of atlas involving hypoplasia of the posterior arch of the atlas, partial ossification of the transverse atlantal ligament, and hypertrophy of the dens. Surgical intervention improved the neurologic impairment.

Increased expression of netrin-1 and its deleted in colorectal cancer receptor in human diseased lumbar intervertebral disc compared with autopsy control.

Study Design. The expression of netrin-1 and its deleted in colorectal cancer (DCC) receptor was investigated in human lumbar discs using immunohistochemistry. Objective. To investigate the expression of netrin-1 and DCC receptor in human diseased and healthy lumbar intervertebral discs (IVDs) and to clarify the correlation between netrin-1 expression and the degree of neurovascular ingrowth. Summary of Background Data. Previous studies have shown neurovascular ingrowth into the inner regions of degenerated IVD and suggested that the ingrowth may contribute to discogenic low back pain. Netrin-1 is an axon guidance molecule that regulates axons seeking their final targets and has been identified as involved in various pathological conditions, so is its DCC receptor. However, the role of netrin-1 in diseased IVDs remains unknown. Methods. Thirty-five diseased IVD specimens were collected from 34 patients with different lumbar diseases during posterior lumbar interbody fusion. Eight normal discs were obtained at autopsy as control. Using polyclonal or monoclonal antibody, the disc slides were immmunostained to detect the expression and distribution of netrin-1, the DCC, the neuronal marker (neurofilament), and the vascular endothelial cell marker (CD34). Results. Netrin-1 and DCC immunopositive cells distributed substantially from the annulus fibrosus to the nucleus pulposus (NP), and the immunopositivity was detected in the disc cells, endothelial cells and granulation tissue cells in the diseased discs. The percentage of netrin-1 positive disc cells of the NP was more than that of the annulus fibrosus. The expression of netrin-1 and DCC was weak in the normal discs. A significant positive correlation between the percentage of netrin-1 immunopositive disc cells and neurovascular scores was found. Conclusion. The increased expression of netrin-1 and DCC in diseased IVDs compared with controls suggested that they might play an important role in the process of neurovascular ingrowth.

Efficacy and Safety of One-Stage Selective Discectomy Combined with Expansive Hemilaminectomy in the Treatment of Cervical Spondylotic Myelopathy

OBJECTIVES We designed a novel surgical strategy named one-stage selective discectomy combined with expansive hemilaminectomy, which might theoretically reduce the postoperative complications of cervical spondylotic myelopathy (CSM). The objective of this study is to evaluate its efficacy and safety. METHODS Sixty-two patients with CSM were enrolled in this study. The procedure includes selective discectomy with fusion at 1 or 2 segments of maximal cord compression and expansive hemilaminectomy on the symptomatic or severe side of the body. Neurologic function was evaluated using the Japanese Orthopedics Association Score before and after surgery. Midsagittal dural sac diameter, dural sac transverse area at segments of discetomy on magnetic resonance imaging, and lordosis of the cervical spine on lateral plain film were measured. All patients were followed up for more than 1 year. RESULTS A total of 88 discs and 272 hemilaminas were resected from 62 patients. The Japanese Orthopedics Association Score improved from 8.7 ± 1.76 preoperatively to 13.4 ± 1.61 at 1 year follow-up (P < 0.001). The mean midsagittal dural sac diameter, dural sac area, and lordotic angle also increased from 0.45 ± 0.10 cm, 0.83 ± 0.14 cm2, and 7.9 ± 2.60° to 0.81 ± 0.08 cm, 0.96 ± 0.14 cm2, and 11.7 ± 3.06°, respectively (P < 0.05). No case of postoperative axial pain, C5 palsy, nonunion, or kyphosis was reported. CONCLUSIONS One-stage selective discectomy combined with expansive hemilaminectomy is an effective surgical approach for the treatment of CSM in patients whose neurologic function, midsagittal dura sac diameter, and dura transverse area can be improved and has few postoperative complications.