Objective

The purpose of the present study was to determine the incidence of dural tears and predictable factors suggesting dural tears in patients who had lumbar burst fractures with vertical laminar fractures.

Methods

A retrospective review was done on thirty-one patients who underwent operative treatment for lumbar burst fractures with vertical laminar fractures between January 2003 and December 2008. All patients were divided into two groups according to existence of dural tears, which were surgically confirmed; 21 patients with dural tears and 10 patients without dural tears. Clinical and radiographic findings were analyzed for their association with dural tears.

Results

Among a total of 31 patients, dural tears were detected in 21 (67%) patients. A preoperative neurological deficits and mean separation distances of the edges in laminar fractures were found to be the reliable factors of dural tears (p=0.001 and 0.002, respectively). Decreased ratio of the central canal diameter and interpedicular distance were also the reliable factors suggesting dural tears (p=0.006 and 0.015, respectively). However, dural tears showed no significant association with age, sex, level of injury, absence of a posterior fat pad signal, the angle of retropulsed segment, or site of laminar fracture.

Conclusion

Our study of lumbar burst fracture combined laminar fracture revealed that dural tears should be ruled out in cases of a preoperative neurological deficits, wide separation of the laminar fracture, severe canal encroachment, and wider interpedicular distance.

Abducens nerve palsy associated with spinal surgery is extremely rare. We report an extremely rare case of abducens nerve palsy after lumbar spinal fusion surgery with inadvertent dural tearing, which resolved spontaneously and completely. A 61-year-old previous healthy man presented with chronic lower back pain of 6 weeks duration and 2 weeks history of bilateral leg pain. He was diagnosed as having isthmic spondylolisthesis at L4-5 and L5-S1, and posterior lumbar interbody fusion was conducted on L4-5 and L5-S1. During the operation, inadvertent dural tearing occurred, which was repaired with a watertight dural closure. The patient recovered uneventfully from general anesthesia and his visual analogue pain scores decreased from 9 pre-op to 3 immediately after his operation. However, on day 2 he developed headache and nausea, which were severe when he was upright, but alleviated when supine. This led us to consider the possibility of cerebrospinal fluid leakage, and thus, he was restricted to bed. After an interval of bed rest, the severe headache disappeared, but four days after surgery he experienced diplopia during right gaze, which was caused by right-side palsy of the abducens nerve. Under conservative treatment, the diplopia gradually disappeared and was completely resolved at 5 weeks post-op.

Objective

Combined antero-posterior fixation has been a standard method for bilateral interfacetal dislocation in cervical spine. The purpose of this study is to evaluate the efficacy and complication of anterior cervical stabilization in treatment of bilateral interfacetal dislocation.

Methods

A total of 65 cases of traumatic bilateral interfacetal dislocation in cervical spine who were managed in our institution, from Mar. 1997 to Feb. 2006, were included in this study. Closed reduction was tried in all cases before operation. If closed reduction was accomplished successfully, only anterior cervical fixation was performed (Group I), and attempted to place screws bicortically as possible with unicortical screws. If failed, posterior open reduction with fixation was first tried, followed by anterior cervical fixation (Group II). All patients were evaluated for neurological outcome and radiological evidence of healing.

Results

The Group I included 47 patients and the Group II, 18 patients. The improvement of Frankel grade and increase of mean cervical lordosis angles were not statistically different between two groups. Screw-plate system used did not influence the outcome. On follow up, solid bone fusion was evident and there were no cases of instability in both groups.

Conclusion

Our study demonstrated that anterior cervical fixation on BID is safe and effective in comparison with combined antero-posterior cervical fixation.

Objective

To evaluate the effect of calcium supplementation on spinal bone fusion in ovariectomized (OVX) rats.

Methods

Sixteen female Sprague Dawley rats underwent bilateral ovariectomy at 12 weeks of age to induce osteoporosis and were randomly assigned to two groups : control group (n=8) and calcium-supplemented group (OVX-Ca, n=8). Autologous spinal bone fusion surgery was performed on both groups 8 weeks later. After fusion surgery, the OVX-Ca group was supplemented with calcium in drinking water for 8 weeks. Blood was obtained 4 and 8 weeks after fusion surgery. Eight weeks after fusion surgery, the rats were euthanized and the L4-5 spine removed. Bone fusion status and fusion volume were evaluated by manual palpation and three-dimensional computed tomography.

Results

The mean fusion volume in the L4-5 spine was significantly greater in the OVX-Ca group (71.80±8.06 mm3) than in controls (35.34±8.24 mm3) (p<0.01). The level of osteocalcin, a bone formation marker, was higher in OVX-Ca rats than in controls 4 weeks (610.08±10.41 vs. 551.61±12.34 ng/mL) and 8 weeks (552.05±19.67 vs. 502.98±22.76 ng/mL) after fusion surgery (p<0.05). The level of C-terminal telopeptide fragment of type I collagen, a bone resorption marker, was significantly lower in OVX-Ca rats than in controls 4 weeks (77.07±12.57 vs. 101.75±7.20 ng/mL) and 8 weeks (69.58±2.45 vs. 77.15±4.10 ng/mL) after fusion surgery (p<0.05). A mechanical strength test showed that the L4-5 vertebrae in the OVX-Ca group withstood a 50% higher maximal load compared with the controls (p<0.01).

Conclusion

Dietary calcium given to OVX rats after lumbar fusion surgery improved fusion volume and mechanical strength in an ovariectomized rat model.

Conventional laminectomy is the most popular technique for the complete removal of intradural spinal tumors. In particular, the central portion intramedullary tumor and large intradural extramedullary tumor often require a total laminectomy for the midline myelotomy, sufficient decompression, and adequate visualization. However, this technique has the disadvantages of a wide incision, extensive periosteal muscle dissection, and bony structural injury. Recently, split-spinous laminectomy and tubular retractor systems were found to decrease postoperative muscle injuries, skin incision size and discomfort. The combined technique of split-spinous laminectomy, using a quadrant tube retractor system allows for an excellent exposure of the tumor with minimal trauma of the surrounding tissue. We propose that this technique offers possible advantages over the traditional open tumor removal of the intradural spinal cord tumors, which covers one or two cervical levels and requires a total laminectomy.

Injury to the bilateral internal branch of superior laryngeal nerve (ibSLN) brings on an impairment of the laryngeal cough reflex that could potentially result in aspiration pneumonia and other respiratory illnesses. We describe a patient with traumatic cervical injury who underwent bilateral ibSLN palsy after anterior cervical discectomy with fusion (ACDF). An 75-year-old man visited with cervical spine fracture and he underwent ACDF through a right side approach. During the post-operative days, he complained of high pitched tone defect, and occasional coughing during meals. With a suspicion of SLN injury and for the work up for the cause of aspiration, we performed several studies. According to the study results, he was diagnosed as right SLN and left ibSLN palsy. We managed him for protecting from silent aspiration. Swallowing study was repeated and no evidence of aspiration was found. The patient was discharged with incomplete recovery of a high pitched tone and improved state of neurologic status. The SLN is an important structure; therefore, spine surgeons need to be concerned and be cautious about SLN injury during high cervical neck dissection, especially around the level of C3-C4 and a suspicious condition of a contralateral nerve injury.

Objective

The purpose of this study was to evaluate the different patterns of bone loss between the lumbar spine and the femur after ovariectomy in rats.

Methods

Twenty-four female Sprague-Dawley rats underwent a sham operation (the sham group) or bilateral ovariectomy (the ovariectomized group). Four and eight weeks after operation, six rats from each of the two groups were euthanized. Serum biochemical markers of bone turnover including osteocalcin and alkaline phosphatase (ALP), which are sensitive biochemical markers of bone formation, and the telopeptide fragment of type I collagen C-terminus (CTX), which is a sensitive biochemical marker of bone resorption, were analyzed. Bone histomorphometric parameters of the 4th lumbar vertebrae and femur were determined by micro-computed tomography.

Results

Ovariectomized rats were found to have higher osteocalcin, ALP and CTX levels than sham controls. Additionally, 8 weeks after ovariectomy in the OVX group, serum levels of osteocalcin, ALP and CTX were significantly higher than those of 4 weeks after ovariectomy. Bone loss after ovariectomy was more extensive in the 4th lumbar spine compared to the femur. Bone loss in the 4th lumbar spine was mainly caused by trabecular thinning, but in the femur, it was mainly caused by trabecular elimination.

Conclusion

The present study demonstrates different patterns of bone loss between the 4th lumbar spine and the femur in ovariectomized rats. Therefore, when considering animal models of osteoporosis, it is important that bone sites should be taken into account.

Objective

The purpose of this study was to verify the appropriateness of ovariectomized rats as the osteoporosis animal model.

Methods

Twelve female Sprague-Dawley rats underwent a sham operation (the sham group) or bilateral ovariectomy [the ovariectomy (OVX) group]. Eight weeks after operations, serum biochemical markers of bone turnover were analyzed; osteocalcin and alkaline phosphatase, which are sensitive biochemical markers of bone formation, and C-terminal telopeptide fragment of type I collagen C-terminus (CTX), which is a sensitive biochemical marker of bone resorption. Bone histomorphometric parameters and microarchitectural properties of 4th lumbar vertebrae were determined by micro-computed tomographic (CT) scan.

Results

The OVX group showed on average 75.4% higher osteocalcin and 72.5% higher CTX levels than the sham group, indicating increased bone turnover. Micro-CT analysis showed significantly lower bone mineral density (BMD) (p=0.005) and cortical BMD (p=0.021) in the OVX group. Furthermore, the OVX group was found to have a significantly lower trabecular bone volume fraction (p=0.002).

Conclusion

Our results showed that bone turnover was significantly increased and bone mass was significantly decreased 8 weeks after ovariectomy in rats. Thus, we propose that the ovariectomized rat model be considered a reproducible and reliable model of osteoporosis.

Hemorrhagic complications associated with aspirin use occur primarily at skin or gastrointestinal sites but can occasionally occur in the central nervous system. In particular, spontaneous spinal epidural hemorrhage (SSEH) associated with aspirin is very rare. We report a case of low-dose (100 mg daily) aspirin-related SSEH that was successfully treated with medical management. Our case indicates that low-dose aspirin could induce SSEH and that conservative treatment with close observation and repeated imaging studies should be considered in cases with neurological improvement or mild deficits.

Objective

Valproic acid (VPA), as known as histone deacetylase inhibitor, has neuroprotective effects. This study investigated the histological changes and functional recovery from spinal cord injury (SCI) associated with VPA treatment in a rat model.

Methods

Locomotor function was assessed according to the Basso-Beattie-Bresnahan scale for 2 weeks in rats after receiving twice daily intraperitoneal injections of 200 mg/kg VPA or the equivalent volume of normal saline for 7 days following SCI. The injured spinal cord was then examined histologically, including quantification of cavitation.

Results

Basso-Beattie-Bresnahan scale scores in rats receiving VPA were significantly higher than in the saline group (p<0.05). The cavity volume in the VPA group was significantly reduced compared with the control (saline-injected) group (p<0.05). The level of histone acetylation recovered in the VPA group, while it was significantly decreased in the control rats (p<0.05). The macrophage level was significantly decreased in the VPA group (p<0.05).

Conclusion

VPA influences the restoration of hyperacetylation and reduction of the inflammatory reaction resulting from SCI, and is effective for histology and motor function recovery.

Objective

It is debatable whether an anterior oblique fracture orientation is really a contraindication to anterior odontoid screw fixation. The purpose of this study was to investigate the feasibility of anterior odontoid screw fixation of type II and rostral shallow type III fracture with an anterior oblique fracture orientation.

Methods

The authors evaluated 16 patients with type II and rostral shallow type III odontoid fracture with an anterior oblique fracture orientation. Of these 16 patients, 8 (group 1) were treated by anterior odontoid screw fixation, and 8 (group 2) by a posterior C1-2 arthrodesis.

Results

Of the 8 patients in group 1, seven patients achieved solid bone fusion (87.5%), and one experienced screw back-out of the C-2 body two months after anterior screw fixation. All patients treated by posterior C1-C2 fusion in group 2 achieved successful bone fusion. Mean fracture displacements and fracture gaps were not significantly different in two groups. (p=0.075 and 0.782). However, mean fracture orientation angles were 15.3±3.2 degrees in group 1, and 28.6+8.1 degrees in group 2 (p=0.002), and mean fragment angulations were 3.2±2.1 degrees in group 1, and 14.8±6.7 degrees in group 2 (p=0.001).

Conclusion

Even when the fracture lines of type II and rostral shallow type III fractures are oriented in an anterior oblique direction, anterior odontoid screw fixation can be feasible in carefully selected patients with a relatively small fracture orientation angle and relatively small fragment angulation.

Vertebral artery (VA) injury is a rare and serious complication of cervical spine surgery; this is due to difficulty in controlling hemorrhage, which can result in severe hypotension and cardiac arrest, and uncertain neurologic consequences. The authors report an extremely rare case of a 56-year-old woman who underwent direct surgical repair by end-to-end anatomosis of an unanticipated VA injury during C2 pedicle screwing. Postoperatively, the patient showed no neurological deterioration and computed tomography angiography of the VA demonstrated normal blood flow. Although direct occlusion of an injured VA by surgical ligation or endovascular embolization has been used for management of an unanticipated VA injury during surgery, these methods may be associated with significant morbidity and mortality. However, despite its technical demand, microvascular primary repair can restore normal blood flow and minimizes the risk of immediate or delayed ischemic complications. Here we report an iatrogenic VA injury during C2 pedicle screwing, which was successfully treated by end-to-end anastomosis.

Extramedullary hematopoiesis (EMH) is occasionally reported in idiopathic myelofibrosis and is generally found in the liver, spleen, and lymph nodes several years after diagnosis. Myelofibrosis presenting as spinal cord compression, resulting from EMH tissue is very rare. A 39-yr-old man presented with back pain, subjective weakness and numbness in both legs. Sagittal magnetic resonance imaging showed multiple anterior epidural mass extending from L4 to S1 with compression of cauda equina and nerve root. The patient underwent gross total removal of the mass via L4, 5, and S1 laminectomy. Histological analysis showed islands of myelopoietic cells surrounded by fatty tissue, consistent with EMH, and bone marrow biopsy performed after surgery revealed hypercellular marrow and megakaryocytic hyperplasia and focal fibrosis. The final diagnosis was chronic idiopathic myelofibrosis leading to EMH in the lumbar spinal canal. Since there were no abnormal hematological findings except mild myelofibrosis, additional treatment such as radiothepary was not administered postoperatively for fear of radiotoxicity. On 6 month follow-up examination, the patient remained clinically stable without recurrence. This is the first case of chronic idiopathic myelofibrosis due to EMH tissue in the lumbar spinal canal in Korea.