Publications by authors named "Chun Kee Chung"

364 Publications

Genetic Odyssey to Ossification of the Posterior Longitudinal Ligament in the Cervical Spine: A Systematic Review.

Neurospine 2022 Jun 30;19(2):299-306. Epub 2022 Jun 30.

Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.

Despite numerous studies, the pathogenesis of ossification of the posterior longitudinal ligament (OPLL) is still unclear. Previous genetic studies proposed variations in genes related to bone and collagen as a cause of OPLL. It is unclear whether the upregulations of those genes are the cause of OPLL or an intermediate result of endochondral ossification process. Causal variations may be in the inflammation-related genes supported by clinical and updated genomic studies. OPLL demonstrates features of genetic diseases but can also be induced by mechanical stress by itself. OPLL may be a combination of various diseases that share ossification as a common pathway and can be divided into genetic and idiopathic. The phenotype of OPLL can be divided into continuous (including mixed) and segmental (including localized) based on the histopathology, prognosis, and appearance. Continuous OPLL shows substantial overexpression of osteoblast-specific genes, frequent upper cervical involvement, common progression, and need for surgery, whereas segmental OPLL shows moderate-to-high expression of these genes and is often clinically silent. Genetic OPLL seems to share clinical features with the continuous type, while idiopathic OPLL shares features with the segmental type. Further genomic studies are needed to elucidate the relationship between genetic OPLL and phenotype of OPLL.
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http://dx.doi.org/10.14245/ns.2244038.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9260552PMC
June 2022

Brain parenchymal angiomatoid fibrous histiocytoma and spinal myxoid mesenchymal tumor with FET: CREB fusion, a spectrum of the same tumor type.

Neuropathology 2022 Aug 22;42(4):257-268. Epub 2022 Jun 22.

Department of Pathology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.

Angiomatoid fibrous histiocytomas (AFH) is a rare soft tissue tumor of intermediate malignant potential, and its histology is diverse. It can occur in several organs including intracranial and soft tissues. Here, we report two cases of brain parenchymal classic AFH and spinal extramedullary myxoid mesenchymal tumor with clinicopathological and molecular investigations by next-generation sequencing and a comprehensive review. The current brain parenchymal AFH occurred in a 79-year-old woman, and the spinal myxoid mesenchymal tumor arose in the thoracic spine of a 28-year-old woman; both harbored FET:CREB fusion. The current brain parenchymal AFH has not recurred for 15-months follow-up period, but the spinal myxoid mesenchymal tumor recurred three times and metastasized to T8 spine level for 30-months follow-up period. We reviewed 40 reported cases of central nervous system (CNS) AFHs/myxoid mesenchymal tumors including our two cases to identify clinicopathological features and biological behaviors. They occur with a slight female predominance (M:F = 1:1.7) in children and young adults (median age: 17 years; range: 4-79 years old). Approximately 80% of CNS AFHs were younger than 30 year. Most of them were dura-based and were not just intracranial tumors as they occurred anywhere in the CNS including spinal dura. EWSR1 rearrangement was the most common driver (98%), including FET:CREB (33%), EWSR1:ATF1 (30%), and EWSR1:CREM (27%) fusions, but FUS:CREM fusion (2%) was also present. During the follow-up period (median: 27 months), 43% (17/40) of CNS AFHs recurred between two months and 11 years, and multiple recurrences were also observed. One case showed metastases to the lymph nodes and vertebrae, and among 11 cases that resulted in death, four cases provided available clinical data. Because these tumors are identical to soft tissue AFH or primary pulmonary myxoid sarcoma with an FET:CREB fusion in morphological and immunohistochemical spectra, the authors propose incorporating the two tumor terms into one.
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http://dx.doi.org/10.1111/neup.12814DOI Listing
August 2022

Validity of magnetic resonance imaging (MRI) in the primary spinal cord tumors in routine clinical setting.

Sci Rep 2022 Jun 16;12(1):10151. Epub 2022 Jun 16.

Department of Neurosurgery, Seoul National University Hospital, Seoul, Republic of Korea.

MRI is the primary diagnostic modality for spinal cord tumors. However, its validity has never been vigorously scrutinized in daily routine clinical practice, where MRI tissue diagnosis is usually not a single one but multiple ones with several differential diagnoses. Here, we aimed to assess the validity of MRI in terms of predicting the pathology and location of the tumor in routine clinical settings. We analyzed 820 patients with primary spinal cord tumors, who have a pathological diagnosis and location in the operation record which were confirmed. We modified traditional measures for validity based upon a set of diagnoses instead of a single diagnosis. Sensitivity and specificity and positive and negative predictabilities were evaluated for the tumor location and pathology. For tumor location, 456 were intradural extramedullary; 165 were intramedullary, and 156 were extradural. The overall sensitivity and specificity were over 90.0%. However, the sensitivity became lower when the tumor resided simultaneously in two spaces such as in the intradural-and-extradural or intramedullary-and-extramedullary space (54.6% and 30.0%, respectively). Most common pathology was schwannoma (n = 416), followed by meningioma (114) and ependymoma (87). Sensitivities were 93.3%, 90.4%, and 89.7%, respectively. Specificities were 70.8%, 82.9%, and 76.0%. In rare tumors such as neurofibromas, and diffuse midline gliomas, the sensitivity was much lower (less than 30%). For common locations and pathologies, the validity of MRI is generally acceptable. However, for rare locations and pathologies, MRI diagnosis still needs some improvement.
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http://dx.doi.org/10.1038/s41598-022-13881-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9203586PMC
June 2022

Parietal and medial temporal lobe interactions in working memory goal-directed behavior.

Cortex 2022 05 8;150:126-136. Epub 2022 Mar 8.

Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, South Korea; Department of Neurosurgery, Seoul National University College of Medicine and Hospital, Seoul, South Korea; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, South Korea. Electronic address:

Working memory is essential for the organization of goal-directed behavior, which involves multiple brain networks. The frontoparietal network has been proposed as a central node for the maintenance and manipulation of information. However, the exact contribution of the frontal and parietal lobes is still unclear as is that of the medial temporal lobe (MTL). Here, we investigated how the frontoparietal network and the MTL coordinate cognitive functions to control working memory in 12 participants, including five men, with medically intractable epilepsy. Participants performed a modified Sternberg working memory task during intracranial electroencephalography recording. The present working memory task was designed to test the different neural states of working memory subprocesses during memory maintenance and operation. First, we observed increased and sustained low-frequency (2-7 Hz) power in the frontal lobe and MTL, relative to baseline activity during the entire working memory task. Parietal alpha (8-13 Hz) power exhibited peak activity during memory operation. Finally, we found a positive correlation in the alpha band between the MTL and the parietal lobe during memory operation. These results indicate that as task demands become specific and goal-directed, the correlation between the MTL and the parietal lobe increases. This finding provides novel insight into the contribution of the MTL-parietal lobe network to voluntary control of working memory.
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http://dx.doi.org/10.1016/j.cortex.2022.02.005DOI Listing
May 2022

Mechanical Failure After Total En Bloc Spondylectomy and Salvage Surgery.

Neurospine 2022 Mar 31;19(1):146-154. Epub 2022 Mar 31.

Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.

Objective: Total en bloc spondylectomy (TES) is a curative surgical method for spinal tumors. After resecting the 3 spinal columns, reconstruction is of paramount importance. We present cases of mechanical failure and suggest strategies for salvage surgery.

Methods: The medical records of 19 patients who underwent TES (9 for primary tumors and 10 for metastatic tumors) were retrospectively reviewed. Previously reported surgical techniques were used, and the surgical extent was 1 level in 16 patients and 2 levels in 3 patients. A titanium-based mesh-type interbody spacer filled with autologous and cadaveric bone was used for anterior support, and a pedicle screw/rod system was used for posterior support. Radiotherapy was performed in 11 patients (pre-TES, 5; post-TES, 6). They were followed up for 59 ± 38 months (range, 11-133 months).

Results: During follow-up, 8 of 9 primary tumor patients (89%) and 5 of 10 metastatic tumor patients (50%) survived (mean survival time, 124 ± 8 months vs. 51 ± 13 months; p = 0.11). Mechanical failure occurred in 3 patients (33%) with primary tumors and 2 patients (20%) with metastatic tumors (p = 0.63). The mechanical failure-free time was 94.4 ± 14 months (primary tumors, 95 ± 18 months; metastatic tumors, 68 ± 16 months; p = 0.90). Revision surgery was performed in 4 of 5 patients, and bilateral broken rods were replaced with dual cobalt-chromium alloy rods. Repeated rod fractures occurred in 1 of 4 patients 2 years later, and the third operation (with multiple cobalt-chromium alloy rods) was successful for over 6 years.

Conclusion: Considering the difficulty of reoperation and patients' suffering, preemptive use of a multiple-rod system may be advisable.
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http://dx.doi.org/10.14245/ns.2244092.046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8987538PMC
March 2022

Diagnostic triage in patients with central lumbar spinal stenosis using a deep learning system of radiographs.

J Neurosurg Spine 2022 Jan 21:1-8. Epub 2022 Jan 21.

4Department of Neurosurgery, Seoul National University Hospital, Seoul.

Objective: Magnetic resonance imaging (MRI) is the gold-standard tool for diagnosing lumbar spinal stenosis (LSS), but it is difficult to promptly examine all suspected cases with MRI considering the modality's high cost and limited accessibility. Although radiography is an efficient screening technique owing to its low cost, rapid operability, and wide availability, its diagnostic accuracy is relatively poor. In this study, the authors aimed to develop a deep learning model with a convolutional neural network (CNN) for diagnosing severe central LSS using radiography and to evaluate radiological diagnostic features using gradient-weighted class activation mapping (Grad-CAM).

Methods: Patients who had undergone both spinal MRI and radiography in the period from May 1, 2005, to December 31, 2017, were screened. According to the formal MRI report, participants were consecutively included in the severe central LSS or healthy control group, and radiographs for both groups were collected. A CNN-based transfer learning algorithm was developed to classify radiographic findings as LSS or normal (binary classification). The proposed models were evaluated using six performance metrics: area under the receiver operating characteristic curve (AUROC), accuracy, sensitivity, specificity, and positive and negative predictive values.

Results: The VGG19 model achieved the highest accuracy with an AUROC of 90.0% (95% CI 89.8%-90.3%) by training 12,442 images. Accuracy was 82.8% (95% CI 82.5%-83.1%) by averaging 5-fold models. Feature points on Grad-CAM were reasonable, and the features could be categorized into reduced disc height, narrow foramina, short pedicle, and hyperdense facet joint. The AUROC in the extra validation was 89.3% (95% CI 88.7%-90.0%). Accuracy was 81.8% (95% CI 80.6%-83.0%) by averaging 5-fold models. Multivariate logistic regression analysis showed that a combination of demographic factors (age and sex) did not improve the model performance.

Conclusions: The algorithm trained by a CNN to identify central LSS on radiographs showed high diagnostic accuracy and is expected to be useful as a triage tool. The algorithm could accurately localize the stenotic lesion to assist physicians in the identification of LSS.
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http://dx.doi.org/10.3171/2021.11.SPINE211136DOI Listing
January 2022

Emerging glioneuronal and neuronal tumors: case-based review.

Brain Tumor Pathol 2022 Apr 20;39(2):65-78. Epub 2022 Jan 20.

Department of Pathology, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.

Glioneuronal and neuronal tumors (GNTs) are rare heterogeneous central nervous system tumors characterized by slow growth and favorable outcomes, but are often associated with diagnostic difficulties. A thorough analysis of three rare and recently recognized GNTs was performed in the context of clinicopathological features and molecular genetic characterization. The current spinal diffuse leptomeningeal glioneuronal tumor (DLGNT) was characterized with oligodendroglioma-like tumor with chromosome 1p/19q codeletion without IDH mutations and KIAA1549:BRAF fusion. The current occipital multinodular and vacuolating neuronal tumor (MVNT) was characteristic of the variable-sized vague nodules consisted of gangliocytic tumor cells with intracytoplasmic and pericellular vacuolation and the next-generation sequencing (NGS) revealed MAP2K1 p.Q56_V60del. A diffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clusters (DGONC) of the amygdala was characterized by oligodendroglia-like cells and nuclear clusters, and monosomy 14. From the current cases and literature review, we found that DLGNT commonly occurs in the spinal cord and can make mass and more commonly have KIAA1549:BRAF fusion; MVNT is a neoplasm rather than malformation and MAP2K1 deletion is one of the hallmarks of this tumor; although DGONC may require a methylation profile, we can reach a diagnosis through its unique histology, monosomy 14, and exclusion diagnosis without a methylation profile.
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http://dx.doi.org/10.1007/s10014-021-00420-3DOI Listing
April 2022

Interlaminar Endoscopic Lumbar Discectomy: A Narrative Review.

Int J Spine Surg 2021 Dec;15(suppl 3):S47-S53

Department of Neurosurgery, Seoul National University Hospital, Seoul, Republic of Korea.

Background: When pain caused by lumbar disc herniation (LDH) is not relieved after 4 to 6 weeks of conservative treatment, surgery is recommended. Open microdiscectomy is a standard surgical technique, but surgical endoscopy enables endoscopic lumbar surgery with clinical outcomes similar to those of standard microdiscectomy. Endoscopic lumbar discectomy is largely divided into transforaminal endoscopic lumbar discectomy (TELD) and interlaminar endoscopic lumbar discectomy (IELD). TELD was introduced about 10 years earlier than IELD and seems to be more popular than IELD.

Objective: The present article reviews the surgical technique, indications, and outcomes of IELD. Although much is still unknown, potential future perspectives are reviewed.

Summary: Although improved surgical techniques enable TELD to be versatile, IELD is still specifically beneficial for patients with highly migrated LDH and a high iliac crest. There is a large body of literature indicating favorable outcomes with both TELD and IELD. Currently, the selection of TELD or IELD is at the discretion of the surgeon, but the IELD surgical technique is useful for further applying endoscopic lumbar surgery for lumbar decompression or lumbar interbody fusion. The techniques can be assisted by advanced technologies such as artificial intelligence, surgical robots, and artificial reality, and a precise and systematic approach to decision-making and surgical techniques is required to combine these technologies effectively.
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http://dx.doi.org/10.14444/8163DOI Listing
December 2021

Structural and functional thalamocortical connectivity study in female fibromyalgia.

Sci Rep 2021 12 2;11(1):23323. Epub 2021 Dec 2.

Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, 08826, Republic of Korea.

Dysfunctional thalamocortical interactions have been suggested as putative mechanisms of ineffective pain modulation and also suggested as possible pathophysiology of fibromyalgia (FM). However, it remains unclear which specific thalamocortical networks are altered and whether it is related to abnormal pain perception in people with FM. Here, we conducted combined vertex-wise subcortical shape, cortical thickness, structural covariance, and resting-state functional connectivity analyses to address these questions. FM group exhibited a regional shape deflation of the left posterior thalamus encompassing the ventral posterior lateral and pulvinar nuclei. The structural covariance analysis showed that the extent of regional deflation of the left posterior thalamus was negatively covaried with the left inferior parietal cortical thickness in the FM group, whereas those two regions were positively covaried in the healthy controls. In functional connectivity analysis with the left posterior thalamus as a seed, FM group had less connectivity with the periaqueductal gray compared with healthy controls, but enhanced connectivity between the posterior thalamus and bilateral inferior parietal regions, associated with a lower electrical pain threshold at the hand dorsum (pain-free point). Overall, our findings showed the structural thalamic alteration interacts with the cortical regions in a functionally maladaptive direction, leading the FM brain more responsive to external stimuli and potentially contributing to pain amplification.
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http://dx.doi.org/10.1038/s41598-021-02616-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8640058PMC
December 2021

Direct medical costs after surgical or nonsurgical treatment for degenerative lumbar spinal disease: A nationwide matched cohort study with a 10-year follow-up.

PLoS One 2021 1;16(12):e0260460. Epub 2021 Dec 1.

Department of Orthopedics, Hallym University Dongtan Sacred Heart Hospital, Gyeonggi, Republic of Korea.

Objective: The demand for treating degenerative lumbar spinal disease has been increasing, leading to increased utilization of medical resources. Thus, we need to understand how the budget of insurance is currently used. The objective of the present study is to overview the utilization of the National Health Insurance Service (NHIS) by providing the direct insured cost between patients receiving surgery and patients receiving nonsurgical treatment for degenerative lumbar disease.

Methods: The NHIS-National Sample Cohort was utilized to select patients with lumbar disc herniation, spinal stenosis, spondylolisthesis or spondylolysis. A matched cohort study design was used to show direct medical costs of surgery (n = 2,698) and nonsurgical (n = 2,698) cohorts. Non-surgical treatment included medication, physiotherapy, injection, and chiropractic. The monthly costs of the surgery cohort and nonsurgical cohort were presented at initial treatment, posttreatment 1, 3, 6, 9, and 12 months and yearly thereafter for 10 years.

Results: The characteristics and matching factors were well-balanced between the matched cohorts. Overall, surgery cohort spent $50.84/patient/month, while the nonsurgical cohort spent $29.34/patient/month (p<0.01). Initially, surgery treatment led to more charge to NHIS ($2,762) than nonsurgical treatment ($180.4) (p<0.01). Compared with the non-surgical cohort, the surgery cohort charged $33/month more for the first 3 months, charged less at 12 months, and charged approximately the same over the course of 10 years.

Conclusion: Surgical treatment initially led to more government reimbursement than nonsurgical treatment, but the charges during follow-up period were not different. The results of the present study should be interpreted in light of the costs of medical services, indirect costs, societal cost, quality of life and societal willingness to pay in each country. The monetary figures are implied to be actual economic costs but those in the reimbursement system instead reflect reimbursement charges from the government.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0260460PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8635587PMC
January 2022

Molecular subtyping of ependymoma and prognostic impact of Ki-67.

Brain Tumor Pathol 2022 Jan 23;39(1):1-13. Epub 2021 Nov 23.

Department of Pathology, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.

Although ependymomas (EPNs) have similar histopathology, they are heterogeneous tumors with diverse immunophenotypes, genetics, epigenetics, and different clinical behavior according to anatomical locations. We reclassified 141 primary EPNs from a single institute with immunohistochemistry (IHC) and next-generation sequencing (NGS). Supratentorial (ST), posterior fossa (PF), and spinal (SP) EPNs comprised 12%, 41%, and 47% of our cohort, respectively. Fusion genes were found only in ST-EPNs except for one SP-EPN with ZFTA-YAP1 fusion, NF2 gene alterations were found in SP-EPNs, but no driver gene was present in PF-EPNs. Surrogate IHC markers revealed high concordance rates between L1CAM and ZFTA-fusion and H3K27me3 loss or EZHIP overexpression was used for PFA-EPNs. The 7% cut-off of Ki-67 was sufficient to classify EPNs into two-tiered grades at all anatomical locations. Multivariate analysis also delineated that a Ki-67 index was the only independent prognostic factor in both overall and progression-free survivals. The gain of chromosome 1q and CDKN2A/2B deletion were associated with poor outcomes, such as multiple recurrences or extracranial metastases. In this study, we propose a cost-effective schematic diagnostic flow of EPNs by the anatomical location, three biomarkers (L1CAM, H3K27me3, and EZHIP), and a cut-off of a 7% Ki-67 labeling index.
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http://dx.doi.org/10.1007/s10014-021-00417-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8752536PMC
January 2022

The Modified 11-Item Frailty Index and Postoperative Outcomes in Patients Undergoing Lateral Lumbar Interbody Fusion.

Spine (Phila Pa 1976) 2022 Mar;47(5):396-404

Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.

Study Design: Retrospective cohort study.

Objective: The aim of this study was to analyze postoperative complications and recovery patterns in different modified 11-item frailty index (mFI-11) groups after lateral lumbar interbody fusion (LLIF) surgery.

Summary Of Background Data: The relationship between the mFI-11 score and LLIF surgery has not been previously reported.

Methods: A single-center, consecutive series of patients who underwent LLIF with at least two years of follow-up were retrospectively reviewed. Complications after LLIF surgery were recorded. Clinical outcomes, including the visual analog scale (VAS) for back/leg pain and the Oswestry Disability Index (ODI), were evaluated preoperatively and at 1 and 2 years postoperatively. The proportions of patients who achieved substantial clinical benefit (SCB) for the VAS-B, VAS-L, and ODI were also analyzed.

Results: One hundred fifty-two patients included in the present study were grouped according to their mFI-11 score: 0 (n = 39), 0.09 (n = 69), 0.18 (n = 31), and ≥0.27 (n = 13). An mFI-11 score ≥0.27 was a significant predictor of urinary complications (adjusted odds ratio: 3.829, P = 0.013). At 2 years postoperatively, patients in all frailty categories experienced improvements in the VAS for back pain, VAS for leg pain, and ODI, without significant differences between the four groups (p = 0.182, 0.121, and 0.804, respectively). There were also no significant differences in the proportions of patients achieving SCB for back/leg pain and the ODI between the four groups (P = 0.843, 0.957, and 0.915, respectively).

Conclusion: An mFI-11 score was found to be independently associated with urologic complications in patients who underwent LLIF. Patients in all frailty categories experienced significant improvements in back pain, leg pain, and the ODI at 1 year and 2 years postoperatively. LLIF surgery may be useful for patients with high frailty index.Level of Evidence: 4.
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http://dx.doi.org/10.1097/BRS.0000000000004260DOI Listing
March 2022

Dissociation of Connectivity for Syntactic Irregularity and Perceptual Ambiguity in Musical Chord Stimuli.

Front Neurosci 2021 30;15:693629. Epub 2021 Aug 30.

Interdisciplinary Program in Neuroscience, College of Natural Science, Seoul National University, Seoul, South Korea.

Musical syntax has been studied mainly in terms of "syntactic irregularity" in harmonic/melodic sequences. However, "perceptual ambiguity" referring to the uncertainty of judgment/classification of presented stimuli can in addition be involved in our musical stimuli using three different chord sequences. The present study addresses how "syntactic irregularity" and "perceptual ambiguity" on musical syntax are dissociated, in terms of effective connectivity between the bilateral inferior frontal gyrus (IFGs) and superior temporal gyrus (STGs) by linearized time-delayed mutual information (LTDMI). Three conditions were of five-chord sequences with endings of dominant to tonic, dominant to submediant, and dominant to supertonic. The dominant to supertonic is most irregular, compared with the regular dominant to tonic. The dominant to submediant of the less irregular condition is the most ambiguous condition. In the LTDMI results, connectivity from the right to the left IFG (IFG-LTDMI) was enhanced for the most irregular condition, whereas that from the right to the left STG (STG-LTDMI) was enhanced for the most ambiguous condition ( = 0.024 in IFG-LTDMI, < 0.001 in STG-LTDMI, false discovery rate (FDR) corrected). Correct rate was negatively correlated with STG-LTDMI, further reflecting perceptual ambiguity ( = 0.026). We found for the first time that syntactic irregularity and perceptual ambiguity coexist in chord stimulus testing musical syntax and that the two processes are dissociated in interhemispheric connectivities in the IFG and STG, respectively.
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http://dx.doi.org/10.3389/fnins.2021.693629DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8435864PMC
August 2021

Endovascular treatment of medullary bridging vein-draining dural arteriovenous fistulas: foramen magnum vs. craniocervical junction lesions.

Neuroradiology 2022 Feb 25;64(2):333-342. Epub 2021 Aug 25.

Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehangno, Jongno-Gu Seoul, Korea.

Purpose: Dural arteriovenous fistulas (AVFs) draining to medullary bridging vein (MBV) are located at foramen magnum (FM) and craniocervical junction (CCJ). Such fistulas are rare but pose a challenge to endovascular management. This study was undertaken to assess clinical manifestations, angiographic features, and outcomes of endovascular treatment in patients with MBV dural AVFs.

Methods: A number of our patients (N = 22) were diagnosed with MBV dural AVF and treated by endovascular means. There were 9 FM lesions and 13 CCJ lesions. We reviewed clinical records and imaging studies to define clinical characteristics, vascular anatomic details, and treatment outcomes, comparing FM- and CCJ-level subsets.

Results: Subjects ranged from 37 to 74 years of age (mean, 57.7 years) with male predominance (2.7:1). They presented with intracranial hemorrhage (11/22, 50%), myelopathy (8/22, 36%), or nonspecific symptoms (3/22, 14%). In 17 patients (77.3%), the shunts showed complete or near-complete occlusion following endovascular treatment (FM, 100%; CCJ, 61.5%). However, seven patients experienced ischemic events (FM, 11.1%; CCJ, 46.2%) and one patient sustained a hemorrhagic complication. No hemorrhages recurred during follow-up monitoring, and myelopathic symptoms abated.

Conclusion: MBV dural AVFs are highly aggressive lesions for which proper diagnosis and treatment are of utmost importance. Although transarterial embolization proved highly successful in FM lesions, shunt occlusion was less frequent in the CCJ subset, with greater risk of ischemic complications.
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http://dx.doi.org/10.1007/s00234-021-02790-zDOI Listing
February 2022

Effects of Total Psoas Area Index on Surgical Outcomes of Single-Level Lateral Lumbar Interbody Fusion.

World Neurosurg 2021 10 17;154:e838-e845. Epub 2021 Aug 17.

Division of Medical Statistics, Medical Research Collaborating Center, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.

Objective: We evaluated the effect of the total psoas area index (TPAI = total psoas muscle area [cm]/height squared [m]) on neurological complications and clinical outcomes after lateral lumbar interbody fusion and identified the appropriate TPAI to achieve a substantial clinical benefit (SCB).

Methods: A consecutive series of 123 patients who had undergone single-level lateral lumbar interbody fusion at a single center with ≥2 years of follow-up were retrospectively reviewed. The patient characteristics and operative data were evaluated. The neurological complications were classified as transient and persistent symptoms. The visual analog scale score for back pain was assessed preoperatively and at 1 and 2 years postoperatively.

Results: The present study included 31 men and 92 women. The mean TPAI was 8.97 cm/m for the men and 5.04 cm/m for the women. The mean TPAI was not significantly different between the patients with and without perioperative neurological complications. Multiple logistic regression analysis showed that solid interbody fusion was the most significant factor for achieving an SCB regarding back pain in men (odds ratio [OR], 2.453; P = 0.019) and women (OR, 2.906; P = 0.042). The TPAI was one of the predictors for achieving an SCB in men (OR, 1.251; P = 0.038) and women (OR, 1.795; P = 0.023). The optimal cutoff point of the TPAI for an SCB was 8.18 cm/m for the men and 4.43 cm/m for the women.

Conclusions: The TPAI had little effect on the incidence of perioperative neurological complications. However, the TPAI was identified as one of the predictors for achieving an SCB regarding back pain.
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http://dx.doi.org/10.1016/j.wneu.2021.08.031DOI Listing
October 2021

Unveiling the genetic variation of severe continuous/mixed-type ossification of the posterior longitudinal ligament by whole-exome sequencing and bioinformatic analysis.

Spine J 2021 11 15;21(11):1847-1856. Epub 2021 Jul 15.

Department of Neurosurgery, Seoul National University Hospital, Seoul; Department of Neurosurgery, Seoul National University College of Medicine; Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, The Republic of Korea. Electronic address:

Background Context: Ossification of the posterior longitudinal ligament (OPLL) in the cervical spine is known as a rare, complex genetic disease, its complexity being partly because OPLL is diagnosed by radiological findings regardless of clinical or genetic evaluations. Although many genes associated with susceptibility have been reported, the exact causative genes are still unknown.

Purpose: We performed an analysis using next-generation sequencing and including only patients with a clear involved phenotype.

Study Design/setting: This was a case control study.

Patient Sample: A total of 74 patients with severe OPLL and 26 healthy controls were included.

Outcome Measures: Causal single-nucleotide variant (SNV), gene-wise variant burden (GVB), and related pathway METHOD: We consecutively included the severe OPLL patients with continuous-/mixed-type and an occupying ratio of ≥ 40%, and performed whole-exome sequencing (WES) and bioinformatic analysis. Then, a validation test was performed for candidate variations. Participants were divided into 4 groups (rapidly-growing OPLL, growing rate ≥ 2.5%/y; slow-growing, < 2.5%/y; uncertain; and control).

Results: WES was performed on samples from 74 patients with OPLL (rapidly-growing, 33 patients; slow-growing, 37; and uncertain, 4) with 26 healthy controls. Analysis of 100 participants identified a newly implicated SNV and 4candidate genes based on GVB. The GVB of CYP4B1 showed a more deleterious score in the OPLL than the control group. Comparison between the rapidly growing OPLL and control groups revealed seven newly identified SNVs. We found significant association for 2 rare missense variants; rs121502220 (odds ratio [OR] = infinite; minor allele frequency [MAF] = 0.034) in NLRP1 and rs13980628 (OR= infinite; MAF = 0.032) in SSH2. The 3 genes are associated with inflammation control and arthritis, and SSH2 and NLRP1 are also related to vitamin D modulation.

Conclusions: Identification of unique variants in novel genes such as CYP4B1 gene may induce the development of OPLL. In subgroup analysis, NLRP1 and SSH2 genes coding inflammation molecules may related with rapidly-growing OPLL.
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http://dx.doi.org/10.1016/j.spinee.2021.07.005DOI Listing
November 2021

Reoperations after fusion surgeries for degenerative spinal diseases depending on cervical and lumbar regions: a national database study.

BMC Musculoskelet Disord 2021 Jul 10;22(1):617. Epub 2021 Jul 10.

Department of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.

Background: Reoperation is one of the key factors affecting postoperative clinical outcomes. The reoperation rates of cervical surgeries might be different from those of lumbar surgeries due to the anatomical and biomechanical differences. However, there has been no study to compare the reoperation rate between them. The purpose is to compare reoperation rates after fusion surgeries for degenerative spinal diseases depending on the anatomic region of cervical and lumbar spines.

Method: We used the Korean Health Insurance Review & Assessment Service national database. Subjects were included if they had any of the primary procedures of fusion combined with the procedure of decompression procedures under the diagnosis of degenerative diseases (n = 42,060). We assigned the patients into two groups based on anatomical regions: cervical and lumbar fusion group (n = 11,784 vs 30,276). The primary endpoint of reoperation was the repeat of any aforementioned fusion procedures. Age, gender, presence of diabetes, associated comorbidities, and hospital types were considered potential confounding factors.

Results: The reoperation rate was higher in the patients who underwent lumbar fusion surgery than in the patients who underwent cervical fusion surgery during the entire follow up period (p = 0.0275). A similar pattern was found during the late period (p = 0.0468). However, in the early period, there was no difference in reoperation rates between the two groups. Associated comorbidities and hospital type were noted to be risk factors for reoperation.

Conclusions: The incidence of reoperation was higher in the patients who underwent lumbar fusion surgery than those who underwent cervical fusion surgery for degenerative spinal diseases.
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http://dx.doi.org/10.1186/s12891-021-04491-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8272907PMC
July 2021

C7 Fracture as a Complication of C7 Dome-Like Laminectomy : Impact on Clinical and Radiological Outcomes and Evaluation of the Risk Factors.

J Korean Neurosurg Soc 2021 Jul 29;64(4):575-584. Epub 2021 Jun 29.

Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.

Objective: Cervical expansive laminoplasty is an effective surgical method to address multilevel cervical spinal stenosis. During surgery, the spinous processes of C2 and C7 are usually preserved to keep the insertion points of the cervical musculature and nuchal ligament intact. In this regard, dome-like laminectomy (undercutting of C7 lamina) instead of laminoplasty is performed on C7 in selected cases. However, resection of the lamina can weaken the C7 lamina, and stress fractures may occur, but this complication has not been characterized in the literature. The objective of the present study was to investigate the incidence and risk factors for C7 laminar fracture after C7 dome-like laminectomy and its impact on clinical and radiological outcomes.

Methods: Patients who underwent cervical open-door laminoplasty combined with C7 dome-like laminectomy (n=123) were classified according to the presence of C7 laminar fracture. Clinical parameters (neck/arm pain score and neck disability index) and radiologic parameters (C2-7 angle, C2-7 sagittal vertical axis, and C7-T1 angle) were compared between the groups preoperatively and at postoperatively at 3, 6, 12, and 24 months. Risk factors for complications were evaluated, and a formula estimating C7 fracture risk was suggested.

Results: C7 lamina fracture occurred in 32/123 (26%) patients and occurred at the bilateral isthmus in 29 patients and at the spinolaminar junction in three patients. All fractures appeared on X-ray within 3 months postoperatively, but patients did not present any neurological deterioration. The fracture spontaneously healed in 27/32 (84%) patients at 1 year and in 29/32 (91%) at 2 years. During follow-up, clinical outcomes were not significantly different between the groups. However, patients with C7 fractures showed a more lordotic C2-7 angle and kyphotic C7-T1 angle than patients without C7 fractures. C7 fracture was significantly associated with the extent of bone removal. By incorporating significant factors, the probability of C7 laminar fracture could be assessed with the formula 'Risk score = 1.08 × depth (%) + 1.03 × length (%, of the posterior height of C7 vertebral body)', and a cut-off value of 167.9% demonstrated a sensitivity of 90.3% and a specificity of 65.1% (area under the curve, 0.81).

Conclusion: C7 laminar fracture can occur after C7 dome-like laminectomy when a substantial amount of lamina is resected. Although C7 fractures may not cause deleterious clinical outcomes, they can lead to an unharmonized cervical curvature. The chance of C7 fracture should be discussed in the shared decision-making process.
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http://dx.doi.org/10.3340/jkns.2021.0024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8273780PMC
July 2021

Prediction of Successful Memory Encoding Based on Lateral Temporal Cortical Gamma Power.

Front Neurosci 2021 25;15:517316. Epub 2021 May 25.

Department of Brain and Cognitive Sciences, Seoul National University, Seoul, South Korea.

Prediction of successful memory encoding is important for learning. High-frequency activity (HFA), such as gamma frequency activity (30-150 Hz) of cortical oscillations, is induced during memory tasks and is thought to reflect underlying neuronal processes. Previous studies have demonstrated that medio-temporal electrophysiological characteristics are related to memory formation, but the effects of neocortical neural activity remain underexplored. The main aim of the present study was to evaluate the ability of gamma activity in human electrocorticography (ECoG) signals to differentiate memory processes into remembered and forgotten memories. A support vector machine (SVM) was employed, and ECoG recordings were collected from six subjects during verbal memory recognition task performance. Two-class classification using an SVM was performed to predict subsequently remembered vs. forgotten trials based on individually selected frequencies (low gamma, 30-60 Hz; high gamma, 60-150 Hz) at time points during pre- and during stimulus intervals. The SVM classifier distinguished memory performance between remembered and forgotten trials with a mean maximum accuracy of 87.5% using temporal cortical gamma activity during the 0- to 1-s interval. Our results support the functional relevance of ECoG for memory formation and suggest that lateral temporal cortical HFA may be utilized for memory prediction.
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http://dx.doi.org/10.3389/fnins.2021.517316DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8185029PMC
May 2021

Dynamic Functional Connectivity Change-Point Detection With Random Matrix Theory Inference.

Front Neurosci 2021 4;15:565029. Epub 2021 May 4.

Department of Neurosurgery, Seoul National University Hospital, Seoul, South Korea.

To study the dynamic nature of brain activity, functional magnetic resonance imaging (fMRI) data is useful including some temporal dependencies between the corresponding neural activity estimates. Recent studies have shown that the functional connectivity (FC) varies according to time and location which should be incorporated into the model. Modeling this dynamic FC (DFC) requires time-varying measures of spatial region of interest (ROI) sets. To know about the DFC, change-point detection in FC is of particular interest. In this paper, we propose a method of detecting a change-point based on the maximum of eigenvalues via random matrix theory (RMT). From covariance matrices for FC of all ROI's, the temporal change-point of FC is decided by an RMT approach. Simulation results show that our proposed method can detect meaningful FC change-points. We also illustrate the effectiveness of our FC detection approach by applying our method to epilepsy data where change-points detected are explained by the changes in memory capacity. Our study shows the possibility of RMT based approach in DFC change-point problem and in studying the complex dynamic pattern of functional brain interactions.
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http://dx.doi.org/10.3389/fnins.2021.565029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8129561PMC
May 2021

Treatment strategy to maximize the treatment outcome of spinal dural arteriovenous fistula after initial endovascular embolization attempt at diagnostic angiography.

Sci Rep 2021 05 11;11(1):10004. Epub 2021 May 11.

Department of Neurosurgery, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 110-744, Korea.

Initial attempt of endovascular treatment (EVT) for spinal dural arteriovenous fistula (SDAVF) is preferred because of concurrent diagnosis and treatment. However, outcomes following further treatment with initial EVT are not well studied. We retrospectively reviewed 71 patients with SDAVF to evaluate treatment outcomes of SDAVF after an initial EVT attempt. Pretreatment and posttreatment functional states were assessed by the Aminoff-Logue scale (ALS). In the case of incomplete occlusion or recurrence, overall outcomes after further treatments were compared. Of the 71 patients, 56 underwent initial EVT. Complete occlusion was achieved by initial EVT in 37 of 56 patients (66.1%). Multiple feeders were more frequently observed in patients with incomplete occlusion than complete occlusion after initial EVT (73.7% vs. 27%, P < 0.001). Among 19 patients with incomplete occlusion upon initial EVT, 14 underwent additional surgery, 13 of whom (92.9%) obtained improved or stationary functional outcomes. Functional improvement was not observed in patients who had repeated EVT or follow-up without further treatment. Recurrence was observed in 8 of 37 patients with complete occlusion upon initial EVT. Additional surgery achieved improved functional outcomes in cases of incomplete occlusion of SDAVF after the initial EVT attempt or recurrence rather than repeated EVT or follow-up.
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http://dx.doi.org/10.1038/s41598-021-89407-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8113326PMC
May 2021

Accuracy and precision of the spinal instability neoplastic score (SINS) for predicting vertebral compression fractures after radiotherapy in spinal metastases: a meta-analysis.

Sci Rep 2021 03 10;11(1):5553. Epub 2021 Mar 10.

Department of Neurosurgery, Seoul National University Hospital, Seoul, Republic of Korea.

Radiotherapy has played an important role in the treatment of spinal metastases. One of the major complications of radiotherapy is vertebral compression fracture (VCF). Although the spinal instability neoplastic score (SINS) was developed for evaluating spinal instability in patients with spinal metastases, it is also commonly used to predict VCF after radiotherapy in patients with spinal metastases. However, its accuracy for predicting radiotherapy-induced VCF and precision remain controversial. The aim of this study was to clarify the diagnostic value of the SINS to predict radiotherapy-induced VCF and to make recommendations for improving its diagnostic power. We searched core databases and identified 246 studies. Fourteen studies were analyzed, including 7 studies (with 1269 segments) for accuracy and 7 studies (with 280 patients) for precision. For accuracy, the area under the summary receiver operating characteristic curve was 0.776. When a SINS cut-off value of 7 was used, as was done in the included studies, the pooled sensitivity was 0.790 and the pooled specificity was 0.546. For precision, the summary estimate of interobserver agreement was the highest dividing 2 categories based on a cut-off value of 7, and the value was 0.788. The body collapse showed moderate relationship and precision with the VCF. The lytic tumor of bone lesion showed high accuracy and fair reliability, while location had excellent reliability, but low accuracy. The SINS system can be used to predict the occurrence of VCF after radiotherapy in spinal metastases with moderate accuracy and substantial reliability. Increasing the cut-off value and revising the domains may improve the diagnostic performance to predict the VCF of the SINS.
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http://dx.doi.org/10.1038/s41598-021-84975-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7947012PMC
March 2021

Surgical treatment of nonlesional temporal lobe epilepsy.

Seizure 2021 Mar 13;86:129-134. Epub 2021 Feb 13.

Department of Neurosurgery, College of Medicine, Seoul National University Hospital, Seoul, Republic of Korea.

Purpose: One-third of the patients with drug-resistant temporal lobe epilepsy (TLE) have a normal MRI, but there are only a few studies regarding the surgical outcomes and the efficacy of anterior temporal lobectomy (ATL) in patients with nonlesional TLE. The objective of this study is to evaluate the surgical outcomes and efficacy of ATL in patients with nonlesional TLE.

Methods: We included 77 consecutive patients without MRI-identifiable lesions who had undergone surgical resection for drug-resistant TLE. We performed univariate and multivariate logistic regression analyses to identify the predictors of surgical outcomes, and the efficacy of ATL in patients with nonlesional TLE.

Results: More than two-thirds of patients (51/76, 67.3 %) had achieved seizure freedom at the last follow-up. Presence of oroalimentary automatism, localized hypometabolism in FDG-PET, and concordant results in presurgical evaluations were associated with better surgical outcomes. Only 15 out of 77 patients (19.2 %) with nonlesional TLE were treated with ATL, and the surgically resected areas were located within the resection margin of ATL in one-third of the patients (26/77, 33.8 %). Patients with auras suggesting neocortical ictal onset and lateralizing semiological features had a higher chance that their potentially epileptogenic areas were located beyond or outside the resection margin of ATL.

Conclusion: Our study showed that the potentially epileptogenic areas were located beyond or outside the margin of the ATL in nearly two-thirds of the patients. Several clinical factors may be useful in predicting the location of an epileptogenic area, which can help optimize a surgical strategy in these patients.
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http://dx.doi.org/10.1016/j.seizure.2021.02.012DOI Listing
March 2021

Nonsurgical treatment outcomes for surgical candidates with lumbar disc herniation: a comprehensive cohort study.

Sci Rep 2021 02 16;11(1):3931. Epub 2021 Feb 16.

Department of Neurosurgery, Yonsei University College of Medicine, 50-1 Yeonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea.

Physicians often encounter surgical candidates with lumbar disc herniation (LDH) who request non-surgical management even though surgery is recommended. However, second opinions may differ among doctors. Therefore, a prospective comprehensive cohort study (CCS) was designed to assess outcomes of nonsurgical treatment for surgical candidates who were recommended to undergo surgery for LDH but requested a second opinion. The CCS includes both randomized and observational cohorts, comprising a nonsurgery cohort and surgery cohort, in a parallel fashion. Crossover between the nonsurgery and surgery cohorts was allowed at any time. The present study was an as-treated interim analysis of 128 cases (nonsurgery cohort, n = 71; surgery cohort, n = 57). Patient-reported outcomes included visual analogue scores for the back (VAS-B) and leg (VAS-L), the Oswestry Disability Index, the EuroQol 5-Dimension instrument, and the 36-Item Short-Form Health Survey (SF-36), which were evaluated at baseline and at 1, 3, 6, 12, and 24 months. At baseline, age and SF-36 physical function were significantly lower in the surgery cohort than in the nonsurgery cohort (p < 0.05). All adjusted outcomes significantly improved after both nonsurgical and surgical treatment (p < 0.05). The nonsurgery cohort showed less improvement of VAS-B and VAS-L scores at 1 month (p < 0.01), but no difference between cohorts was observed thereafter for 24 months (p > 0.01). Nonsurgical management may be a negotiable option even for surgical candidates in the shared decision-making process.
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http://dx.doi.org/10.1038/s41598-021-83471-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7887235PMC
February 2021

Characterization of kinesthetic motor imagery compared with visual motor imageries.

Sci Rep 2021 02 12;11(1):3751. Epub 2021 Feb 12.

Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, 08826, Republic of Korea.

Motor imagery (MI) is the only way for disabled subjects to robustly use a robot arm with a brain-machine interface. There are two main types of MI. Kinesthetic motor imagery (KMI) is proprioceptive (OR somato-) sensory imagination and Visual motor imagery (VMI) represents a visualization of the corresponding movement incorporating the visual network. Because these imagery tactics may use different networks, we hypothesized that the connectivity measures could characterize the two imageries better than the local activity. Electroencephalography data were recorded. Subjects performed different conditions, including motor execution (ME), KMI, VMI, and visual observation (VO). We tried to classify the KMI and VMI by conventional power analysis and by the connectivity measures. The mean accuracies of the classification of the KMI and VMI were 98.5% and 99.29% by connectivity measures (alpha and beta, respectively), which were higher than those by the normalized power (p < 0.01, Wilcoxon paired rank test). Additionally, the connectivity patterns were correlated between the ME-KMI and between the VO-VMI. The degree centrality (DC) was significantly higher in the left-S1 at the alpha-band in the KMI than in the VMI. The MI could be well classified because the KMI recruits a similar network to the ME. These findings could contribute to MI training methods.
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http://dx.doi.org/10.1038/s41598-021-82241-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7881019PMC
February 2021

Prognosis of Symptomatic Pseudarthrosis Observed at 1 Year After Lateral Lumbar Interbody Fusion.

Spine (Phila Pa 1976) 2021 Sep;46(18):E1006-E1013

Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.

Study Design: Retrospective cohort study.

Objective: The aim of this study was to investigate the prognosis of symptomatic pseudarthrosis observed at 1 year after lateral lumbar interbody fusion (LLIF) surgery and to analyze the risk factors for persistent pseudarthrosis for 2 years postoperatively.

Summary Of Background Data: Few articles have evaluated the prognosis of symptomatic pseudarthrosis following LLIF surgery.

Methods: One hundred fifty-two patients with a minimum follow-up of 2 years were screened. Fusion status was assessed at 1 year postoperatively, and unfused segments were reevaluated at 2 years postoperatively. Dynamic x-rays and computed tomography images were acquired to evaluate the fusion status. Demographic data were evaluated to identify the risk factors associated with persistent pseudarthrosis. Clinical outcomes, including the visual analog scale (VAS) for back/leg pain and the Oswestry disability index (ODI), were evaluated preoperatively and at 1 and 2 years postoperatively.

Results: Symptomatic pseudarthrosis was detected in 42 patients at 1 year postoperatively. Among them, 23 patients (54.8%) exhibited solid bony fusion 2 years postoperatively without further intervention. Fourteen patients (33.3%) showed asymptomatic pseudarthrosis, and the remaining five patients (11.9%) showed symptomatic pseudarthrosis. Multivariable analysis showed that diabetes (adjusted odds ratio [OR]: 2.817, P = 0.007), smoking (adjusted OR: 6.497, P = 0.008), and fusion at more than three levels (adjusted OR: 2.525, P = 0.031) were risk factors for persistent pseudarthrosis. Improvements in the VAS scores for back pain and ODI scores were significantly lower in the persistent pseudarthrosis group than in the final solid fusion group at 2 years postoperatively.

Conclusion: It is not necessary to intervene for all patients in whom symptomatic pseudarthrosis is detected at 1 year postoperatively because only 11.9% of them will show persistent symptomatic pseudarthrosis. However, early revision surgery should be considered when severe symptomatic pseudarthrosis associated with diabetes, smoking, and fusion at more than three levels is present.Level of Evidence: 4.
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http://dx.doi.org/10.1097/BRS.0000000000003980DOI Listing
September 2021

Posterior-only versus combined anterior-posterior fusion in Scheuermann disease: a systematic review and meta-analysis.

J Neurosurg Spine 2020 Dec 25;34(4):608-616. Epub 2020 Dec 25.

1Department of Neurosurgery, Seoul National University Hospital.

Objective: Combined anterior-posterior (AP) surgery is considered the gold standard for surgical treatment of Scheuermann kyphosis. There are trends toward posterior-only (PO) surgery for correcting this deformity because of the availability of multisegmental compression instruments and posterior shortening osteotomy. To date, surgical strategies for Scheuermann kyphosis remain controversial. The purpose of this study was to compare various surgical approaches for the treatment of Scheuermann kyphosis, including radiological correction and intraoperative outcomes, using a systematic review and meta-analysis.

Methods: A comprehensive database search of PubMed, EMBASE, Web of Science, and Cochrane Library was performed to identify studies concerning Scheuermann kyphosis. The inclusion criteria were direct comparisons between AP and PO surgeries for Scheuermann kyphosis and assessment of the angle of thoracic kyphosis preoperatively and postoperatively. The authors used the principles of a cumulative meta-analysis by updating the pooled estimate of the treatment effect.

Results: Data from 13 studies involving 1147 participants (542 patients in the AP group and 605 patients in the PO group) were included. The average age was 18.2 years for the AP and 17.9 years for the PO group. The overall mean difference of changes in thoracic kyphosis angles between the AP and PO surgeries was 0.23° (95% CI -2.24° to 2.71°). In studies in which posterior shortening osteotomies were not performed, PO surgery resulted in a significantly low degree of correction of thoracic kyphosis, with a mean difference of 5.59° (95% CI 0.34°-10.83°). Studies in which osteotomies were performed revealed that the angle of correction for PO surgery was comparable to that of AP surgery. Regardless of fixation methods, PO surgical approaches achieved comparable angles.

Conclusions: PO surgery using posterior osteotomies can achieve correction of Scheuermann kyphosis as successfully as AP surgery does. Reflecting the advancement of surgical technology, large prospective studies are necessary to identify the proper treatments for Scheuermann kyphosis.
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http://dx.doi.org/10.3171/2020.7.SPINE201062DOI Listing
December 2020

Intraoperative Radiographs in Single-level Lateral Lumbar Interbody Fusion Can Predict Radiographic and Clinical Outcomes of Follow-up 2 Years After Surgery.

Spine (Phila Pa 1976) 2021 Jun;46(11):772-780

Division of Medical Statistics, Medical Research Collaborating Center, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.

Mini: Some of the improvements in DH, FH, and SLL achieved intraoperatively during lateral lumbar interbody fusion surgery were lost by the postoperative 1-week follow-up. An intraoperative radiograph can predict radiographic and clinical outcomes of the 2-year follow-up. The difference between preoperative DH and intraoperative DH should be >4.18 mm.
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http://dx.doi.org/10.1097/BRS.0000000000003889DOI Listing
June 2021

Single-Trial EEG Connectivity of Default Mode Network Before and During Encoding Predicts Subsequent Memory Outcome.

Front Syst Neurosci 2020 19;14:591675. Epub 2020 Nov 19.

Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea.

The successful memory process produces specific activity in the brain network. As the brain activity of the prestimulus and encoding phases has a crucial effect on subsequent memory outcomes (e.g., remembered or forgotten), previous studies have tried to predict the memory performance in this period. Conventional studies have used the spectral power or event-related potential of specific regions as the classification feature. However, as multiple brain regions work collaboratively to process memory, it could be a better option to use functional connectivity within the memory-related brain network to predict subsequent memory performance. In this study, we acquired the EEG signals while performing an associative memory task that remembers scene-word pairs. For the connectivity analysis, we estimated the cross-mutual information within the default mode network with the time-frequency spectra at the prestimulus and encoding phases. Then, we predicted the success or failure of subsequent memory outcome with the connectivity features. We found that the classifier with support vector machine achieved the highest classification accuracy of 80.83% ± 12.65% (mean ± standard deviation) using the beta (13-30 Hz) connectivity at encoding phase among the multiple frequency bands and task phases. Using the prestimulus beta connectivity, the classification accuracy of 72.45% ± 12.52% is also achieved. Among the features, the connectivity related to the dorsomedial prefrontal cortex was found to contribute to successful memory encoding. The connectivity related to the posterior cingulate cortex was found to contribute to the failure of memory encoding. The present study showed for the first time the successful prediction with high accuracy of subsequent memory outcome using single-trial functional connectivity.
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http://dx.doi.org/10.3389/fnsys.2020.591675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7710990PMC
November 2020

A prospective study of non-surgical versus surgical treatment for lumbar spinal stenosis without instability.

J Clin Neurosci 2020 Oct 17;80:100-107. Epub 2020 Aug 17.

Division of Medical Statistics, Medical Research Collaborating Center, Seoul National University Hospital, Seoul, Republic of Korea.

Objective: Even if analyzed through meta-analyses or systemic reviews ensued lately, we could say that at least it is inconclusive which of the surgical or non-surgical treatment to lumbar spinal stenosis is better particularly in short to intermediate-term. This study compared non-surgical and surgical outcomes in surgical candidates for lumbar spinal stenosis (LSS).

Methods: Surgical candidates for LSS were prospectively screened. Patients were offered the option to be enrolled in a randomized cohort, an observational cohort, or not to participate. Patient-reported outcomes were evaluated at baseline, and at 1, 3, 6, and 12 months. The primary outcomes were measures of pain and functional outcomes such as the Korean version of the Oswestry Disability Index (K-ODI), the EuroQol 5-Dimension instrument (EQ-5D), and 36-Item Short-Form Health Survey (SF-36).

Results: One hundred and ten patients were enrolled in the randomized cohort and 37 patients in the observational cohort. Among them, 97 patients received non-surgical treatment, and 50 patients underwent surgical treatment. At 12 months, the non-surgical treatment group had less improvements in the primary outcome measures of back pain (mean change: non-surgery, 2.34 vs. surgery, 3.99), leg pain (2.92 vs. 3.40), K-ODI (5.12 vs. 8.31), EQ-5D utility index (0.19 vs. 0.25), and EQ-5D VAS (9.68 vs. 16.0). Most SF-36 section parameters also showed less improvement in the non-surgical treatment group than in the surgical treatment group throughout the 12-month follow-up.

Conclusions: In LSS patients without instability, non-surgical treatment resulted in less pain improvement and functional recovery through 1 year.
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http://dx.doi.org/10.1016/j.jocn.2020.07.062DOI Listing
October 2020
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