Nuclear import of LIKE HETEROCHROMATIN PROTEIN1 is redundantly mediated by importins α-1, α-2 and α-3.

LIKE HETEROCHROMATIN PROTEIN1 (LHP1) encodes the only plant homologue of the metazoan HETEROCHROMATIN PROTEIN1 (HP1) protein family. The LHP1 protein is necessary for proper epigenetic regulation of a range of developmental processes in plants. LHP1 is a transcriptional repressor of flowering-related genes, such as FLOWERING LOCUS T (FT), FLOWERING LOCUS C (FLC), AGAMOUS (AG) and APETALA 3 (AP3). We found that LHP1 interacts with importin α-1 (IMPα-1), importin α-2 (IMPα-2) and importin α-3 (IMPα-3) both in vitro and in vivo. A genetic approach revealed that triple mutation of impα-1, impα-2 and impα-3 resulted in Arabidopsis plants with a rapid flowering phenotype similar to that of plants with mutations in lhp1 due to the upregulation of FT expression. Nuclear targeting of LHP1 was severely impaired in the impα triple mutant, resulting in the de-repression of LHP1 target genes AG, AP3 and SHATTERPROOF 1 as well as FT. Therefore, the importin proteins IMPα-1, -2 and -3 are necessary for the nuclear import of LHP1.

The ligamentotactic effect on a herniated disc at the level adjacent to the anterior lumbar interbody fusion : report of two cases.

The authors report two cases of spontaneous regression of disc herniation at the level adjacent to the anterior lumbar interbody fusion (ALIF) level. This phenomenon may be due to the increased tension on the posterior longitudinal ligament (PLL) by appropriate restoration of the disc height and lumbar lordosis, which is a mechanism similar to ligamentotaxis applied to the thoracolumbar burst fracture.

Spinal cord herniation after multilevel anterior cervical corpectomy and fusion for ossification of the posterior longitudinal ligament of the cervical spine.

The authors report the case of a 52-year-old man who had undergone resection of an ossified posterior longitudinal ligament via the anterior approach. The patient experienced postoperative neurological deterioration that may have been caused by a massive cord herniation associated with a dural defect at the corpectomy site. Spinal cord herniation may develop as a complication of anterior cervical decompression. Surgeons should be alert to this condition when planning to treat cervical ossification of the ossified posterior longitudinal ligament via the anterior approach.

Influence of lumbar lordosis restoration on thoracic curve and sagittal position in lumbar degenerative kyphosis patients.

STUDY DESIGN: A retrospective study. OBJECTIVES: To determine postsurgical correlations between thoracic and lumbar sagittal curves in lumbar degenerative kyphosis (LDK) and to determine predictability of spontaneous correction of thoracic curve and sacral angle after surgical restoration of lumbar lordosis and fusion. SUMMARY OF BACKGROUND DATA: To our knowledge, there are only a limited number of articles about the relationship between thoracic and lumbar curve in sagittal thoracic compensated LDK. METHODS: Retrospective review of 53 consecutive patients treated with combined anterior and posterior spinal arthrodesis. We included patients with sagittal thoracic compensated LDK caused by sagittal imbalance in this study. Total lumbar lordosis, thoracic kyphosis, sacral slope, and C7 plumb line were measured on the pre- and postoperative whole spine lateral views. Postoperative changes in thoracic kyphosis, sacral slope, and C7 plumb line according to the surgical lumbar lordosis restoration were measured and evaluated. RESULTS: The mean preoperative sagittal imbalance by plumb line was 78.3 mm (+/-76.5); this improved to 13.6 mm (+/-25) after surgery (P < 0.0001). Mean lumbar lordosis was 9.4 degrees (+/-19.2) before surgery and increased to 38.4 degrees (+/-13.1) at follow-up (P < 0.0001). Mean thoracic kyphosis was 1.1 degrees (+/-12.7) before surgery and increased to 17.6 degrees (+/-12.2) at follow-up (P < 0.0001). Significant preoperative correlations existed between kyphosis and lordosis (r = 0.772, P < 0.0001) and between lordosis and sacral slope (r = 0.785, P < 0.0001). Postoperative lumbar lordosis is correlated to thoracic kyphosis increase (r = 0.620, P < 0.0001). Postoperative lumbar lordosis is correlated to sacral slope increase (r = 0.722, P < 0.0001). CONCLUSION: Reciprocal relationship exists between lumbar lordosis and thoracic kyphosis in sagittal thoracic compensated LDK. Surgical restoration of lumbar lordosis for LDK brings about high level of statistical correlation to thoracic kyphosis improvement. At the same time, the reciprocal relationship is maintained.

Can patients with sagittally well-compensated lumbar degenerative kyphosis benefit from surgical treatment for intractable back pain?

OBJECTIVE: To analyze pre- and postoperative x-rays of sagittal spines and to review the surgical results of 21 patients with lumbar degenerative kyphosis whose spines were sagittally well compensated by compensatory mechanisms but who continued to suffer from intractable back pain METHODS: We performed a retrospective review of 21 patients treated with combined anterior and posterior spinal arthrodesis. Inclusion criteria were: lumbar degenerative kyphosis patients with intractable back pain and whose spines were sagittally well compensated by a compensatory mechanism, defined as a C7 plumb line to the posterior aspect of the L5-S1 disc of less than 5 cm. Outcome variables included: radiographic measures of preoperative, postoperative, and follow-up films; clinical assessment using the mean Numeric Rating Scale, Oswestry Disability Index, and Patient Satisfaction Index; and a review of postoperative complications. RESULTS: All patients were female (mean age, 64.5 years; age range, 50-74 years). The mean preoperative sagittal imbalance was 19.5 (+/- 17.6) mm, which improved to -15.8 (+/- 22.2) mm after surgery. Mean lumbar lordosis was 13.2 degrees (+/- 15.3) before surgery and increased to 38.1 degrees (+/- 14.4) at follow-up (P < 0.0001). Mean thoracic kyphosis was 5.5 degrees (+/- 10.2) before surgery and increased to 18.9 degrees (+/- 12.4) at follow-up (P < 0.0001). Mean sacral slopes were 12.9 degrees (+/- 11.1) before surgery and increased to 26.3 degrees (+/- 9.6) at follow-up (P < 0.0001). The mean Numeric Rating Scale score improved from 7.8 (back pain) and 8.1 (leg pain) before surgery to 3.0 (back pain) and 2.6 (leg pain) after surgery (P < 0.0001). The mean Oswestry Disability Index scores improved from 56.2% before surgery to 36.7% after surgery (P < 0.0001). In 18 (85.5%) of 21 patients, satisfactory outcomes were demonstrated by the time of the last follow-up assessment. CONCLUSION: This study shows that even lumbar degenerative kyphosis patients with spines that are sagittally well compensated by compensatory mechanisms may suffer from intractable back pain and that these patients can be treated effectively by the restoration of lumbar lordosis.

The clinical characteristics and risk factors for the adjacent segment degeneration in instrumented lumbar fusion.

STUDY DESIGN: A retrospective study. OBJECTIVE: The aims of this study were to evaluate the clinical significance of, characteristics of, and risk factors for adjacent segment degeneration (ASD) in patients who have undergone instrumented lumbar fusion. SUMMARY OF BACKGROUND DATA: ASD has been considered a potential long-term complication of spinal arthrodesis. However, the exact mechanisms and risk factors related to ASD are not completely understood. METHODS: A total of 48 patients who underwent instrumented lumbar fusion at L4-5 and had minimal ASD preoperatively were evaluated. The patients were divided into 2 groups at follow-up according to the development of ASD defined by radiologic criteria. Through review of their medical records and the radiologic files, the following variables were evaluated in the 2 groups: basic demographic data, body weight, body height, body mass index, bone mineral density, types of surgical approaches, preoperative and postoperative segmental and lumbar lordosis, and clinical outcomes. RESULTS: ASD was found in 30 (62.5%) patients. The variables that showed statistical intergroup differences were the mean age at surgery, the mean difference in the degree of preoperative from postoperative lumbar lordosis, and the proportion of patients who underwent anterior lumbar interbody fusion. However, there were no statistically significant intergroup differences in the Japanese Orthopedic Association score at 1-year postoperatively or at the final follow-up, or in the recovery rate, success rate, and complication rate. CONCLUSIONS: Radiographic ASD is relatively common long-term finding associated with instrumented lumbar fusion. However, radiographic evidence of ASD does not necessarily correlate with a poor outcome. Our results suggest that advanced age, anterior lumbar interbody fusion, and the restoration of the preoperative standing lumbar lordosis may have a protective effect against the development of ASD.

Clinical results of ossification of the posterior longitudinal ligament (OPLL) of the thoracic spine treated by anterior decompression.

STUDY DESIGN: A retrospective study. OBJECTIVE: To evaluate surgical outcomes and prognostic factors of thoracic ossification of the posterior longitudinal ligament (OPLL) treated by anterior decompression. SUMMARY OF BACKGROUND DATA: The results of surgery for thoracic myelopathy caused by OPLL have been recognized as unfavorable. Anterior decompression is the logical treatment option for thoracic OPLL, but it is technically demanding and is associated with a high rate of complications. METHODS: Nineteen patients who underwent anterior decompression were included in this study. Modified Japanese Orthopedic Association (JOA) scores and recovery rates were used to evaluate the outcomes. The relationship between the recovery rate and the following factors was investigated statistically: age, sex, duration of symptoms, preoperative JOA score, the degree of stenosis, the extent of decompression, the type of OPLL, the presence of signs of dural penetration, the presence of cerebrospinal fluid leakage, the presence of high signal intensity in the cord, and the presence of coexisting pathologies requiring surgical intervention. RESULTS: The final outcome was excellent in 4 (21.1%) patients, good in 2 (10.5%), fair in 7 (36.8%), unchanged in 4 (21.1%), and worsened in 2 (10.5%). The only statistically significant factor affecting outcomes was the preoperative JOA score. The complications included 2 (10.5%) patients with neurologic deterioration and 6 (31.6%) patients with cerebrospinal fluid leakage. CONCLUSIONS: We evaluated the outcomes and factors affecting the surgical outcomes of 19 patients with thoracic OPLL treated with anterior decompression. In this small series, we found that some patients undergoing anterior decompression for thoracic OPLL clinically improved, however, a significant percentage did not. Anterior decompression is technically demanding and is associated with a high rate of complications. When poor preoperative JOA scores and immediate postoperative neurologic deterioration are present, poor outcomes may be expected.

Clinical significance of redundant nerve roots of the cauda equina in lumbar spinal stenosis.

OBJECTIVES: The aim of this study was to evaluate the significance of redundant nerve roots (RNR) in lumbar stenosis by comparative analysis of a group of patients with RNR with a group without RNR. PATIENTS AND METHODS: A total of 68 patients who underwent decompressive laminotomies for single-level lumbar stenosis were divided into two groups. Group I included patients with RNR, and group II included patients with no RNR (NRNR). RNR were defined as a tortuosity of elongated and coiled nerve roots in the subarachnoid space associated with spinal stenosis demonstrable by sagittal images of MRI. Comparative analysis was performed. RESULTS: RNR was found in 33.8% of patients with stenosis. Patients in the RNR groups were older than those in the NRNR group. There were no statistically significant differences between the two groups with regard to the duration of symptoms, preoperative and final Japanese Orthopaedic Association's (JOA) scores, diameter of the spinal canal, recovery rate, and success rate of the surgery. However, the final JOA scores, recovery rate, and success rate showed a tendency to be better in the NRNR group. In the RNR group, the longer the relative length of RNR, the better the outcome. CONCLUSIONS: RNR is a relatively common finding in association with spinal stenosis. It tends to develop in patients of more advanced age than patients with no RNR. Surgical outcomes in the RNR group were not statistically different from those in the NRNR group, although NRNR group showed slightly better outcomes.

Surgical treatment of failed back surgery syndrome due to sagittal imbalance.

STUDY DESIGN: Retrospective study of consecutive patient series. OBJECTIVE: To review the etiology of failed back surgery syndrome due to sagittal imbalance and radiographic and clinical results of surgical treatment of these patients who were treated with combined anterior and posterior arthrodesis. SUMMARY OF BACKGROUND DATA: Sagittal imbalance after spinal fusion surgery may be a major source of pain and disability. Preventing iatrogenic sagittal imbalance should be a key objective during spinal fusion surgery. METHODS: Retrospective review of revision spine surgery due to sagittal imbalance treated with combined anterior and posterior spinal arthrodesis in the 19 patients. Outcome variables included radiographic measures of preoperative, postoperative, and follow-up films, and a clinical assessment using the Verbal Analogue Scale (VAS), Oswestry Disability Index, Macnab criteria, Satisfactory Index Instrument, and a review of postoperative complications. RESULTS: Mean age was 62 years (range, 49-74 years), and mean follow-up was 31 months (range, 24-37 months) for clinical and radiographic outcome variables. The mean preoperative sagittal imbalance was 116 (+/-65) mm, which improved to 32 mm (+/-29) after surgery. Mean lumbar lordosis was 15 degrees (+/-20 degrees) before surgery, and increased to 38 degrees (+/-13 degrees) at follow-up, an increase of 23 degrees. The mean VAS improved from 7.2 (back pain), 6.8 (leg pain) before the surgery to 3 (back pain), 3.2 (leg pain) after the surgery (P < 0.0001). The mean Oswestry Disability Index scores improved from 62 (+/-11) before the surgery to 36 (+/-12) after the surgery (P < 0.0001). Excellent or good outcome was demonstrated in 16 patients (84.2%). CONCLUSION: Most common causes of revision spine surgery due to sagittal imbalance were failure to enhance lumbar lordosis and adjacent disc degeneration after lumbar fusion surgery. These patients were effectively treated with a combined anterior and posterior arthrodesis. Following these surgical treatment, sagittal balance was generally improved with fair-to-good clinical outcomes, high patient satisfaction, and low perioperative complication rates.

Lumbar degenerative kyphosis: radiologic analysis and classifications.

STUDY DESIGN: Retrospective study of a consecutive patient series. OBJECTIVES: To review the radiographic classification of patients with sagittal imbalance due to lumbar degenerative kyphosis (LDK) and to determine correlation between thoracic and lumbar curve. SUMMARY OF BACKGROUND DATA: Lumbar degenerative kyphosis is one of the common spinal deformities in Asian countries, especially Korea and Japan. However, there have been few studies regarding the classification and treatment of this disease. METHODS: Seventy-eight patients with LDK were analyzed and classified according to the standing lateral whole spine findings. Total lumbar lordosis (L1-S1), thoracic kyphosis (T5-T12), sacral slope, thoracolumbar angle (T11-L1), and sagittal vertical axis (SVA) were measured on the lateral view of the whole spine. Spinal curve deformities were classified into 2 groups according to the thoracolumbar (T-L) junction angle: flat or lordotic angle (Group 1; N = 53) and kyphotic angle (Group 2; N = 25). RESULTS: In Group 1, significant correlations between the thoracic and lumbar curves (r = 0.772, P < 0.0001), and between the lumbar curve and sacral slope (r = 0.785, P < 0.0001) were observed. By this result, Group 1 was classified as sagittal thoracic compensated group. In contrast, In Group 2, no correlation was found between the thoracic and lumbar curves in the decompensated group (r = 0.179, P = 0.391), but we found a significant correlation between lordosis and sacral slope (r = 0.442, P = 0.027). By this result, Group 2 was classified as sagittal thoracic decompensated group. There was significant difference in SVA between 2 groups (P = 0.020). CONCLUSION: The angle of the thoracolumbar junction is an important parameter in determining whether a sagittal thoracic compensatory mechanism exists in LDK. We assumed that existence of a compensatory mechanism in the proximal spine is central to the determination of the fusion levels in the treatment of LDK.

Changes in sagittal alignment after restoration of lower lumbar lordosis in patients with degenerative flat back syndrome.

OBJECT: The authors investigate the correlation between thoracic and lumbar curves in patients with degenerative flat back syndrome, and demonstrate the predictability of spontaneous correction of the thoracic curve and sacral angle after surgical restoration of lower lumbar lordosis. METHODS: The cases of 28 patients treated with combined anterior and posterior spinal arthrodesis were retrospectively reviewed. Inclusion criteria included loss of lower lumbar lordosis resulting in sagittal imbalance. Total lumbar lordosis, thoracic kyphosis, sacral slope, and C-7 plumb line length were measured on pre- and postoperative lateral views of the whole spine. Postoperative changes in thoracic kyphosis, sacral slope, and length of the C-7 plumb line were measured and evaluated according to extent of lumbar lordosis restoration. RESULTS: The mean (+/- standard deviation) preoperative sagittal imbalance was 64.6 +/- 63.2 mm, which improved to 15.8 +/- 20.7 mm after surgery (p < 0.0001). The preoperative mean lumbar lordosis was 15.6 +/- 14.1 degrees, which increased to 40.3 +/- 14.5 degrees at follow-up (p < 0.0001). The preoperative mean thoracic kyphosis was 1.6 +/- 10.5 degrees and increased to 17.2 +/- 12.5 degrees at follow-up (p < 0.0001). Significant preoperative correlations existed between kyphosis and lordosis (r = 0.628, p = 0.0003), and between lordosis and sacral slope (r = 0.647, p = 0.0002). Postoperative correlations also existed between kyphosis and lordosis (r = 0.718, p < 0.0001 and r = 0.690, p < 0.0001, respectively). CONCLUSIONS: Lower lumbar lordosis plays an important role in sagittal alignment and balance. Surgical restoration of lumbar lordosis results in predictable spontaneous correction of the thoracic curve and sacral slope in patients with degenerative flat back syndrome.

Comparison of anterior- and posterior-approach instrumented lumbar interbody fusion for spondylolisthesis.

OBJECT: The purpose of this study was to compare the imaging and clinical outcomes obtained in patients with lumbar spondylolisthesis who have undergone either instrumented anterior lumbar interbody fusion (ALIF) or instrumented posterior LIF (PLIF), especially with regard to the development of adjacent-segment degeneration (ASD). METHODS: Forty-eight patients with preoperative spondylolisthesis and minimal ASD who underwent instrumented L4-5 fusion were divided into two groups according to the surgical approach. After ensuring the two groups' comparability, the following variables were evaluated: postoperative segmental and lumbar lordosis, postoperative percentage of vertebral slippage, reduction rate, incidence of ASD, and clinical outcomes. RESULTS: Adjacent-segment degeneration was found in 44.0% of the patients in the ALIF group and in 82.6% of those in the PLIF group (p = 0.008). Clinical success rates were 92.0 and 87.0% in the ALIF and PLIF groups, respectively. There were no statistically significant intergroup differences in the postoperative segmental and lumbar lordosis, postoperative percentage of slippage, reduction rate, Japanese Orthopaedic Association score, and success rate. CONCLUSIONS: Both ALIF and PLIF can produce good outcomes in treating lumbar spondylolisthesis, but ALIF is more advantageous in preventing the development of ASD.

Significance of the double- and single-layer signs in the ossification of the posterior longitudinal ligament of the thoracic spine.

OBJECTIVE: The purpose of this study was to elucidate the significance of the signs of dural ossification applied to the thoracic ossification of the posterior longitudinal ligament (OPLL), as originally described for cervical OPLL by Hida et al. METHODS: Twenty patients with thoracic OPLL who underwent anterior decompression were retrospectively studied through examination of preoperative computed tomographic scans and medical records. The types of OPLL, single- and double-layer signs, as well as actual dural penetration were evaluated. RESULTS: Signs of dural ossification were found in 80.0% of the patients. There were 10 (71.4%) cases of a dural ossification sign among the 14 patients with segmental OPLL and six (100%) cases of a dural ossification sign among the six patients with non-segmental OPLL. Dural defects were present in six (60.0%) out of 10 patients with a double-layer sign and three (50.0%) out of six patients with a single-layer sign. CONCLUSION: There are several differences between thoracic and cervical OPLL in regard to dural ossification signs. The incidence of these signs with thoracic OPLL was higher than that with cervical OPLL, and these signs can develop in a segmental OPLL as frequently as in a non-segmental OPLL. Dural defects were present in 60% of the patients with a double-layer sign and in 50% of the patients with a single-layer sign. Therefore, surgeons should be alert for the high possibility of a dural defect when these signs are present in thoracic OPLL, although, a dural defect can develop even in the absence of the signs.

Significance of the double-layer and single-layer signs in the ossification of the posterior longitudinal ligament of the cervical spine.

OBJECT: The purpose of this study was to elucidate the significance of the signs of dural penetration, which were previously described by Hida et al. This goal was accomplished by an analysis of preoperative computed tomography scans and a review of the medical records of patients who underwent removal of the ossification of the posterior longitudinal ligament (OPLL) via the anterior approach. METHODS: Outcomes in 197 patients with cervical OPLL who underwent anterior decompression and fusion were studied retrospectively. The types of OPLL, single- and double-layer signs of dural penetration, diameter of the central hypodense mass of the double-layer sign, and the presence of actual dural penetration were evaluated. Signs of dural penetration were found in 30.5% of patients. These signs were much more prevalent in patients with nonsegmental OPLL. Dural defects were present in 20 (52.6%) of 38 patients with double-layer signs and in three (13.6%) of 22 patients with single-layer signs. Among patients in the double-layer sign group, the mean diameter of the central hypodense masses was thicker in the group with an actual dural defect. Although not to the degree reported by Hida et al., the double-layer sign had a significant association with dural defects. In particular, the thicker the central hypodense mass of the double-layer sign, the greater the possibility of a dural defect. However, a single-layer sign had less significance than a double-layer one. CONCLUSIONS: Surgeons should be alert to the increased possibility of a dural defect when there is a double-layer sign with a thick central hypodense mass in nonsegmental OPLL.

Hyperostotic meningioma with minimal tumor invasion into the skull.

A 56-year-old man presented with a meningioma associated with hyperostotic bone containing little tumor cell infiltration. The patient presented with a growing mass on his right forehead and exophthalmos. Computed tomography (CT) taken 4 years previously revealed only hyperostosis without intracranial lesion. Repeat CT revealed an enhanced intracranial mass with overlying diffuse hyperostosis extending extracranially. The tumor and affected bone were widely removed. Histological examination confirmed rhabdoid meningioma in the intracranial and extracranial lesion. However, most of the hyperostotic bone showed no tumor cell infiltration. The cause of hyperostosis associated with meningioma is unclear, but tumor invasion is the generally accepted cause. In this case, hyperostosis occurred without tumor cell infiltration so another mechanism was probably involved. The extracranial extension occurred despite the disproportionately small tumor without global tumor cell infiltration of the bone or bony erosion.

Anatomic analysis of the transforaminal ligament in the lumbar intervertebral foramen.

OBJECTIVE: The objective of this study was to evaluate the clinical significance of the transforaminal ligaments (TFLs) in relation to the area of the lumbar intervertebral foramen (IVF) by analyzing cadaveric spines. METHODS: One hundred ninety-eight cadaveric lumbar IVFs were studied, and the existence and type of TFLs were identified. All IVFs were photographed, and the images were saved. The areas of the IVFs and TFLs were measured with the Scion Image for Windows image analysis program. RESULTS: TFLs were found in 82.8% of the IVFs. The oblique inferior transforaminal ligament was the most common. The mean area of the IVFs was 155.8 +/- 51.1 mm2, and the mean area occupied by the TFLs was 46.3 +/- 37.6 mm2. The mean percentage of the IVF area occupied by the TFLs was 28.5 +/- 18.8%. CONCLUSION: TFLs are common structures in the IVF and may reduce the space available for the spinal nerve root within the IVF. In this circumstance, any compromise of the IVF may impinge on the nerve root.

Morphometric analysis of the working zone for endoscopic lumbar discectomy.

OBJECTIVE: Our study's purpose was to analyze the working zone for the current practice of endoscopic discectomy at the lateral exit zone of the intervertebral foramen (IVF) and to define a safe point for clinical practice. METHODS: One hundred eighty-six nerve roots of the lumbar IVFs of cadaveric spines were studied. Upon lateral inspection, we measured the distance from the nerve root to the most dorsolateral margin of the disc and to the lateral edge of the superior articular process of the vertebra below at the plane of the superior endplate of the vertebra below. The angle between the root and the plane of the disc was also measured. RESULTS: The results showed that the mean distance from the nerve root to the most dorsolateral margin of the disc was 3.4 +/- 2.7 mm (range 0.0-10.8 mm), the mean distance from the nerve root to the lateral edge of the superior articular process of the vertebra below was 11.6 +/- 4.6 mm (range 4.1-24.3 mm), and the mean angle between the nerve root and the plane of the disc was 79.1 degrees +/- 7.6 degrees (range 56.0-90.0 degrees ). CONCLUSIONS: The values of the base of the working zone have a wide distribution. Blind puncture of annulus by the working cannula or obturator may be dangerous. The safer procedure would be the direct viewing of the annulus by endoscopy before annulotomy; the working cannula should be inserted into the foramen as close as possible to the facet joint.