Chi Heon Kim

Reoperation rate after surgery for lumbar herniated intervertebral disc disease: nationwide cohort study.

Study Design. Retrospective cohort study using national health insurance data. Objective. To provide a longitudinal reoperation rate after surgery for lumbar herniated intervertebral disc (HIVD) disease, and to compare the reoperation rates of surgical methods. Summary of Background Data. Herniated intervertebral disc disease is the most common cause of lumbar spinal surgery. Despite improved surgical techniques and instrumentation, reoperation cannot be avoided. The reoperation rates were in the range of 6% to 24% in previous studies. A population-based study is less subject to bias; hence, a nationwide longitudinal analysis was warranted. Methods. A national health insurance database was used to identify a cohort of patients who underwent first surgery for herniated intervertebral disc disease in 2003 and 18,590 patients were selected. Individual patients were followed for at least 5 years through their encrypted unique resident registration number. The primary endpoint was any type of second lumbar surgery. After adjusting for confounding factors, 5 surgical methods (fusion, laminectomy, open discectomy, endoscopic discectomy, and nucleolysis [including mechanical nucleus decompression]) were compared. Open discectomy was used as the reference method. Results. Open discectomy was the most common procedure (68.9%) followed by endoscopic discectomy (16.1%), laminectomy (7.9%), fusion (3.9%), and nucleolysis (3.2%). The cumulative reoperation rate was 5.4% at 3 months, 7.4% at 1 year, 9% at 2 years, 10.5% at 3 years, 12.1% at 4 years, and 13.4% at 5 years. The reoperation rates were 18.6%, 14.7%, 13.8%, 12.4%, and 11.8% after laminectomy, nucleolysis, open discectomy, endoscopic discectomy, and fusion, respectively. Compared with open discectomy, the reoperation rate was higher after laminectomy at 3 months, whereas the other surgical methods had similar rates. Conclusion. The cumulative reoperation rate after 5 years was 13.4% and half of the reoperations occurred during the first postoperative year. With the exception of laminectomy, the reoperation rates of the other procedures were not different from that of open discectomy.

Gamma knife surgery of superficially located meningioma

OBJECT The authors analyzed tumor control rates and complications in patients with superficially located meningiomas after gamma knife surgery (GKS). METHODS Between 1998 and 2003, GKS was performed in 23 patients with 26 lesions in whom follow-up imaging for 1 year or more was available. The male/female ratio was 1:22. The mean age was 59 years. The median tumor volume was 4.7 cm3, and the mean margin dose was 16 Gy at the 50% isodose line. Peritumoral edema was revealed on magnetic resonance (MR) imaging in four patients before GKS. Magnetic resonance imaging and clinical examinations were performed every 6 months after GKS. The mean follow-up duration was 32 months. The tumor shrank in eight cases, was stable in 17, and enlarged in one; thus 25 (95%) of 26 tumors were controlled. A peritumoral high signal on T2-weighted MR images was found in eight lesions and preexisting edema was aggravated in three lesions after GKS. Ten of these 11 patients complained of severe headache, and three patients experienced neurological deficits at the same time after a mean latency of 3 months; however, high signal was not demonstrated on imaging before 6 months on average. Steroid agents, when required, gave relief to all patients. The complication rate was 43% (10 of 23 cases). High signal disappeared in nine patients and decreased in the remaining two. High signal was associated with a high integral dose and a large tumor volume. Tumor shrinkage at the last follow-up examination was more prominent in the patients with symptomatic high signal (p = 0.03). CONCLUSIONS There was a good tumor control rate with a high complication rate. Longer follow up of more patients is needed. Adjusting the dose-volume relationship should be considered to reduce complications.

A new high-performance poly-Si TFT by simple excimer laser annealing on selectively floating a-Si layer

A new poly-Si TFT with a single grain-boundary has been fabricated by a simple ELA method which employs a selectively floating a-Si active layer. A thermally insulating air-gap between the floating a-Si and substrate successfully induces the lateral grain growth. Large lateral grains exceeding 4 /spl mu/m have been grown by a single laser irradiation with wide ELA process window. The proposed poly-Si TFT exhibits high mobility of 331 cm/sup 2//V sec due to the high-quality grains.

Long-term outcomes of surgical resection with or without adjuvant radiation therapy for treatment of spinal ependymoma: a retrospective multicenter study by the Korea Spinal Oncology Research Group

BACKGROUND We sought to determine the surgical treatment and functional outcome and identify the predictors of survival in a retrospective cohort of patients with spinal cord ependymoma using data collected from the Korea Spinal Oncology Research Group database. METHODS The data regarding 88 patients who had been surgically treated for histologically confirmed spinal cord intramedullary and extramedullary ependymoma from January 1989 to December 2009 were retrospectively reviewed. RESULTS Histopathological examination revealed myxopapillary ependymoma in 24 patients, ependymoma in 61 patients, and anaplastic ependymoma in 3 patients. Gross total removal was achieved in 72 patients, subtotal removal in 15 patients, and partial removal in 1 patient. Twenty patients were treated with postoperative radiation. Fifty-two patients had stable or improved postoperative neurological function, while 36 experienced neurological deterioration. A permanent decrease in McCormick classification grade was seen in 17 patients. The progression-free survival rate was 87% for all patients at 5 years and 80% at 10 years. During follow-up, local recurrence/progression was seen in 13 patients. Diffuse meningeal spread developed in 2 anaplastic ependymoma patients. Postoperative radiotherapy after incomplete resection did not significantly correlate with longer times to recurrence. Multivariate analysis revealed histology and surgical extent of resection as independent predictors of longer progression-free survival. CONCLUSIONS Gross total removal alone is a good treatment strategy for spinal ependymomas. Early diagnosis and surgery, before severe paralysis, are important to obtain good functional outcomes. Subtotal resection with radiation therapy for intramedullary lesions appears to offer no advantages over gross total removal.

Comparisons of outcomes after single or multilevel dynamic stabilization: effects on adjacent segment.

Study Design A retrospective study. Objectives To compare the clinical/radiologic outcomes and effects on adjacent segments by Dynesys stabilization. Summary of Background Data Dynamic stabilization is known to preserve some range of motion (ROM) and to lessen the load on adjacent levels compared with rigid fixation. However, there is concern about the stiffness of Dynesys. In a long-term follow-up study (>4 y), motion of Dynesys was preserved in only 8% of patients and adjacent segment degeneration occurred up to 47% of patients. Little information is available about the risk factor regarding adjacent segment motion. Methods Twenty-one patients underwent lumbar spine stabilization with Dynesys owing to degenerative spinal disease (single, 7; multiple-level, 14). Clinical outcomes were evaluated using K-ODI, VAS, and MacNab criteria. Radiologic evaluations included whole spine AP/lateral, lumbar neutral, flexion, and extension x-ray. Follow-up period was 31±14 months. Single (group A) and multiple-level stabilization (group B, average 2.3 levels) were compared. Results Clinical improvement was not different between the 2 groups (P>0.05). Sagittal balance, lumbar lordosis, ROM of the lumbar spine, pelvic tilt, and sacral slope were not changed postoperatively (P>0.05) in either group. Postoperatively, ROM of stabilized segments were significantly decreased from 12.8±4.8 degrees to 3.9±5 degrees, while ROM of segments above was increased in both groups (P<0.01). Disc height was not decreased in either group (P>0.05). However, retrolisthesis was observed on adjacent segments above in 6 patients only in group B, which may suggests adjacent segment problem. Conclusions Clinically, dynamic stabilization is a good alternative treatment option for degenerative spinal disease. However, dynamic stabilization preserves only limited motion and may cause stress on the adjacent level above. Adjacent segment disease may be closely monitored, especially in cases of multiple-levels dynamic stabilization.

Thalamic changes in temporal lobe epilepsy with and without hippocampal sclerosis: A diffusion tensor imaging study

OBJECTIVE The seizure network may be different between temporal lobe epilepsy with hippocampal sclerosis (TLE+HS) and without HS (TLE-HS). Chronic seizure activity may alter the diffusion properties of a seizure network. The thalamus is known to have an anatomical connection to the medial temporal area and to play a role in seizure modulation. This study aimed to evaluate differences in thalamic changes between TLE+HS and TLE-HS with diffusion tensor imaging (DTI). METHODS Nine patients with TLE+HS and nine patients with TLE-HS were included in the study. All patients underwent surgery with good seizure outcomes. Hippocampal sclerosis was verified pathologically. Sixteen right-handed, normal subjects were enrolled as controls. DTI was acquired using 3.0 T MRI. The mean diffusivity (MD) and fractional anisotropy (FA) were calculated in the center of the bilateral thalamus with the DTIstudio program. RESULTS The MD of bilateral thalami increased in both TLE groups compared to controls (p<0.05), while FA values did not differ from controls. The MD of the thalamus ipsilateral to the epileptogenic side was higher in the TLE+HS group than in the TLE-HS group (p=0.007). Onset age, seizure duration, seizure frequency and total seizure number were not correlated with FA and MD changes (p>0.05). CONCLUSION Bilateral thalamic diffusion properties are altered in temporal lobe epilepsy. The presence of hippocampal sclerosis enhances the change ipsilaterally.

Autologous iliac bone graft with anterior plating is advantageous over the stand-alone cage for segmental lordosis in single-level cervical disc disease.

BACKGROUND Anterior cervical discectomy and fusion (ACDF) with autologous iliac bone graft and plating has been a standard surgical method for single-level cervical disc disease. The stand-alone cage was introduced to reduce graft-related morbidity. However, problems due to focal kyphosis at the operated level have been on the rise. It has been difficult to derive a conclusive answer from previous studies for the indications of each method. OBJECTIVE An interim analysis of a prospective randomized study was performed to compare the sagittal alignment between a stand-alone cage (ACDF cage) and autologous iliac bone graft and plating (ACDF plate). METHODS Twenty-nine patients were allocated to the ACDF-cage group (M:F = 17:12) and 23 to the ACDF-plate group (M:F = 14:9). Cobb angles at the operated segment (segmental angle, SA; lordosis vs kyphosis) were compared at postoperative 12 months and the other confounding factors were explored. RESULTS Demographic features were not different between groups. The fusion method significantly affected segmental alignment at 12 months (P = .03; odds ratio, 5.52). Preoperatively, the SA was not different between the groups (P = .18) and was similar (P = .22) immediately following the operation. However, the SA was significantly more lordotic (P < .05) in the ACDF-plate group at postoperative 12 months in comparison with the ACDF-cage group. There was no other significant risk factor for segmental kyphosis. CONCLUSION The stand-alone cage and autologous bone graft with plating had similar clinical outcomes, but stand-alone cage fusion may be disadvantageous from a radiological viewpoint.

Less invasive palliative surgery for spinal metastases.

There may be patients with spinal metastasis for whom neither vertebroplasty/kyphoplasty nor open surgery is appropriate. Percutaneous pedicle screw fixation (PPSF) may fill the gap between techniques.

Postoperative survival and ambulatory outcome in metastatic spinal tumors : prognostic factor analysis.

OBJECTIVE The purposes of this study are to estimate postoperative survival and ambulatory outcome and to identify prognostic factors thereafter of metastatic spinal tumors in a single institute. METHODS We reviewed the medical records of 182 patients who underwent surgery for a metastatic spinal tumor from January 1987 to January 2009 retrospectively. Twelve potential prognostic factors (age, gender, primary tumor, extent and location of spinal metastases, interval between primary tumor diagnosis and metastatic spinal cord compression, preoperative treatment, surgical approach and extent, preoperative Eastern Cooperative Oncology Group (ECOG) performance status, Nurick score, Tokuhashi and Tomita score) were investigated. RESULTS The median survival of the entire patients was 8 months. Of the 182 patients, 80 (44%) died within 6 months after surgery, 113 (62%) died within 1 year after surgery, 138 (76%) died within 2 years after surgery. Postoperatively 47 (26%) patients had improvement in ambulatory function, 126 (69%) had no change, and 9 (5%) had deterioration. On multivariate analysis, better ambulatory outcome was associated with being ambulatory before surgery (p=0.026) and lower preoperative ECOG score (p=0.016). Survival rate was affected by preoperative ECOG performance status (p<0.001) and Tomita score (p<0.001). CONCLUSION Survival after metastatic spinal tumor surgery was dependent on preoperative ECOG performance status and Tomita score. The ambulatory functional outcomes after surgery were dependent on preoperative ambulatory status and preoperative ECOG performance status. Thus, prompt decompressive surgery may be warranted to improve patients survival and gait, before general condition and ambulatory function of patient become worse.

Surgical Outcome of Percutaneous Endoscopic Interlaminar Lumbar Discectomy for Highly Migrated Disk Herniation.

Study Design:Technical report. Objective:To present a detailed surgical technique for percutaneous endoscopic interlaminar discectomy (PEID) for highly migrated disk herniation. Summary of Background Data:Percutaneous lumbar endoscopic discectomy for highly migrated disk herniation is still challenging even for an experienced surgeon. Because of the risk of failure and technical difficulty, open discectomy is recommended for a high-grade migration. However, past reports focused on the transforaminal approach (percutaneous endoscopic transforaminal discectomy) and may give a biased impression. We may overlook the merit of PEID. The surgical procedure for PEID is similar to a traditional open discectomy and the range of approach could be widened by the inclined introduction and pivoting motion of an endoscope. Methods:Eighteen consecutive patients (M:F=12:6; age, 56±15 y) with highly migrated disk herniation were enrolled for the present study. The disk material was migrated superiorly in 7 patients (L4–5, 4; L5–S1, 2; L2–3, 1) and inferiorly in 11 patients (L4–5, 6; L3–4, 4; L5–S1, 1). PEID was applied in 17 patients and PETD was performed for L2–3 disk herniation. The follow-up period was 16±12 months. The outcome was graded using the MacNab criteria. Results:Complete removal of the disk material was confirmed with magnetic resonance imaging in 16 patients (success rate 89%). Revision operation was necessary in 2 patients with inferior migration from L4–5. The residual disk was removed through the L5–S1 laminar window 2 days after surgery with excellent outcome at the last follow-up. The outcome at the last follow-up was excellent in 12 patients, good in 3, fair in 2, and poor in 1. Dural tear was suspected in 1 patient without any further problems and there was no recurrence during follow-up. Conclusions:PEID may be applied comfortably even for less-experienced surgeons because of the familiar anatomy with open surgery.