Objective: Multilevel posterior cervical fusion (PCF) and decompression surgery is a viable treatment option for multilevel ossification of posterior longitudinal ligament (OPLL) and spondylotic myelopathy. Since OPLL is known to affect bone formation, this study aimed to examine the effect of OPLL on the incidence of pseudarthrosis following PCF in a cohort study. Methods: We conducted a retrospective cohort study of patients with PCF and laminectomy at our institution. This study included patients who underwent C3 to C6 posterior fusion surgery involving lateral mass screw fixation without anterior surgery for OPLL or spondylotic myelopathy. Fusion status was evaluated 1 year postoperatively with computed tomography. Bone mineral density (BMD) and sagittal parameters were also evaluated as potential contributing factors to the fusion rate. Results: Eighty patients were included. Pseudarthrosis was observed in 22.5% (n=18) of patients. Pseudarthrosis incidence was lower in patients with OPLL (spondylosis vs. OPLL, 33.3% vs. 12.2%; p=0.003), and a higher BMD T-score (pseudarthrosis vs. fusion, -1.9 ± 0.7 vs. -0.6 ± 1.3; p<0.01), a larger preoperative range of motion (ROM) (26.7 ± 13.3 vs. 17.6 ± 10.9; p=0.01), and a greater preoperative-to-postoperative decrease in cervical lordosis (-8.1 ± 7.9 vs. -2.7 ± 7.9; p<0.01). Pseudarthrosis was associated with worsening neck pain after surgery. Conclusion The absence of OPLL, lower BMD, larger preoperative ROM, and a greater decrease in postoperative cervical lordosis were identified as risk factors for pseudarthrosis after multiple PCF.

Objective: : Spinal intramedullary hemangioblastoma is a rare and highly vascularized benign tumor. The characteristics of the tumor, its corresponding location, and surgical outcomes remain unknown. The purpose of this study was to identify risk factors and strategies for neurologic deterioration following hemangioblastoma surgery. Methods: : A comprehensive retrospective analysis was undertaken to evaluate patients who underwent surgical intervention for intramedullary hemangioblastoma at our institution from 1993 to 2022. Patients with at least 1 year of follow-up data were included. The analysis covered patient demographics, pre- and post-operative modified McCormick scale (MMCS), tumor location, and tumor size. Results: : This study included 25 cases. One-year after surgery, neurological deterioration was observed in five cases (20.0%), and neurological improvement was found in nine cases (36.0%). Five cases were ventrally located, and twelve cases were dorsally located. Ventrally located cases were larger in tumor axial size (p=0.029) than dorsal location tumors, resulting in poorer follow-up MMCS and a higher prevalence of von Hippel-Lindau syndrome (VHL) (p=0.042). Three of them were confirmed to be supplied by the anterior spinal artery. In the case of dorsally located cases, there was no neurologic deterioration. Conclusion : In intramedullary spinal cord hemangioblastomas, cases located ventrally had a higher incidence of neurological deterioration following surgery than those located dorsally or in intramedullary extramedullary cases. Ventrally located hemangioblastomas were larger than those in other locations. They were mainly supplied by the anterior spinal artery in VHL patients.

Objective: : This study aimed to investigate the efficacy of transverse process (TP) hook system at the upper instrumented vertebra (UIV) for preventing screw pullout in adult spinal deformity surgery using the pedicle Hounsfield unit (HU) stratification based on K-means clustering. Methods: : We retrospectively reviewed 74 patients who underwent deformity correction surgery between 2011 and 2020 and were followed up for >12 months. Pre- and post-operative data were used to determine the incidence of screw pullout, UIV TP hook implementation, vertebral body HU, pedicle HU, and patient outcomes. Data was then statistically analyzed for assessment of efficacy and risk prediction using stratified HU at UIV level alongside the effect of the TP hook system. Results: : The screw pullout rate was 36.4% (27/74). Perioperative radiographic parameters were not significantly different between the pullout and non-pullout groups. The vertebral body HU and pedicle HU were significantly lower in the pullout group. K-means clustering stratified the vertebral body HU ≥205.3, <137.2, and pedicle HU ≥243.43, <156.03. The pullout rate significantly decreases in patients receiving the hook system when the pedicle HU was from ≥156.03 to < 243.43 (p<0.05), but the difference was not statistically significant in the vertebra HU stratified groups and when pedicle HU was ≥243.43 or <156.03. The postoperative clinical outcomes improved significantly with the implementation of the hook system. Conclusion : The UIV hook provides better clinical outcomes and can be considered a preventative strategy for screw-pullout in the certain pedicle HU range.

Purpose: The biplanar whole body imaging system (EOS) is a new tool for measuring the whole body sagittal alignment in a limited space. This tool may affect the sagittal balance of patients compared to conventional whole spine X-ray (WSX). This study aimed to investigate the difference in sagittal alignment between WSX and EOS. Materials and Methods: We compared the spinal and pelvic sagittal parameters in 80 patients who underwent EOS and WSX within one month between July 2018 and September 2019. The patients were divided based on sagittally balanced and imbalanced groups according to pelvic tilt (PT) >20°, pelvic incidence-lumbar lordosis >10°, C7-sagittal vertical axis (SVA) > 50 mm in WSX. Results: In the sagittally imbalanced group, compared to WSX, the pelvic parameters demonstrated compensation in EOS with smaller PT (27.4±11.6° vs. 24.9±10.9°, p=0.003) and greater sacral slope (SS), and the patients tended to stand more upright with smaller C7-SVA (58.4±17.0 mm vs. 48.9±57.3 mm, p=0.018), T1-pelvic angle (TPA), T5-T12, and T2-T12. However, in the sagittally balanced group, these differences were less pronounced only with smaller PT (10.8±6.9° vs. 9.4±4.7°, p=0.040), TPA and T2-T12 angle, but with similar SS and C7-SVA (p>0.05). Conclusion EOS showed a negative SVA shift and lesser PT compared to WSX, especially in patients with sagittal imbalance. When preparing a surgical plan, surgeons should consider these differences between EOS and WSX.

Objective: To compare the clinical and radiological features of various etiologies of chronic diffuse lacrimal gland enlargement. Materials and Methods: We retrospectively reviewed 91 consecutive patients who underwent surgical biopsy for chronic diffuse lacrimal gland enlargement and were diagnosed with non-specific dacryoadenitis (DA) (n = 42), immunoglobulin G4-related dacryoadenitis (IgG4-RD) (n = 33), and lymphoma (n = 16). Data on patient demographics, clinical presentation, and CT imaging findings (n = 73) and MRI (n = 43) were collected. The following radiologic features of lacrimal gland enlargement were evaluated: size, unilaterality, wedge sign, angle with the orbital wall, heterogeneity, signal intensity, degree of enhancement, patterns of dynamic contrast-enhanced, and apparent diffusion coefficient value. Radiological features outside the lacrimal glands, such as extra-lacrimal orbital involvement and extra-orbital head and neck involvement, were also evaluated. The clinical and radiological findings were compared among the three diseases. Results: Compared to the DA and IgG4-RD groups, the lymphoma group was significantly older (mean 59.9 vs. 46.0 and 49.4 years, respectively; p = 0.001) and had a higher frequency of unilateral involvement (62.5% vs. 31.0% and 15.2%, respectively;p = 0.004). Compared to the IgG4-RD and lymphoma groups, the DA group had significantly smaller lacrimal glands (2.3 vs. 2.8 and 3.3 cm, respectively; p < 0.001) and a lower proportion of cases with a wedge sign (54.8% vs. 84.8% and 87.5%, respectively; p = 0.005). The IgG4-RD group showed more frequent involvement of the extra-orbital head and neck structures, including the infraorbital nerve (36.4%), paranasal sinus (72.7%), and salivary gland (58.6%) compared to the DA and lymphoma groups (4.8%–28.6%) (all p < 0.005). Conclusion Patient age, unilaterality, lacrimal gland size, wedge sign, and extra-orbital head and neck involvement differed significantly different between lymphoma, DA, and IgG4-RD. Our results will be useful for the differential diagnosis and proper management of chronic lacrimal gland enlargement.

Purpose: The biplanar whole body imaging system (EOS) is a new tool for measuring the whole body sagittal alignment in a limited space. This tool may affect the sagittal balance of patients compared to conventional whole spine X-ray (WSX). This study aimed to investigate the difference in sagittal alignment between WSX and EOS. Materials and Methods: We compared the spinal and pelvic sagittal parameters in 80 patients who underwent EOS and WSX within one month between July 2018 and September 2019. The patients were divided based on sagittally balanced and imbalanced groups according to pelvic tilt (PT) >20°, pelvic incidence-lumbar lordosis >10°, C7-sagittal vertical axis (SVA) > 50 mm in WSX. Results: In the sagittally imbalanced group, compared to WSX, the pelvic parameters demonstrated compensation in EOS with smaller PT (27.4±11.6° vs. 24.9±10.9°, p=0.003) and greater sacral slope (SS), and the patients tended to stand more upright with smaller C7-SVA (58.4±17.0 mm vs. 48.9±57.3 mm, p=0.018), T1-pelvic angle (TPA), T5-T12, and T2-T12. However, in the sagittally balanced group, these differences were less pronounced only with smaller PT (10.8±6.9° vs. 9.4±4.7°, p=0.040), TPA and T2-T12 angle, but with similar SS and C7-SVA (p>0.05). Conclusion EOS showed a negative SVA shift and lesser PT compared to WSX, especially in patients with sagittal imbalance. When preparing a surgical plan, surgeons should consider these differences between EOS and WSX.

Langerhans cell histiocytosis (LCH) is reported less frequently in adults than in children. The most common site of involvement in adults is the bone, accounting for 30-50% of cases. The gastrointestinal tract is very rare, accounting for approximately 2%. We present a case of Langerhans cell histiocytosis that simultaneously invaded multiple organs, including the stomach and colon, in an adult. A 37-year-old woman with no underlying disease complained of chest discomfort and a palpable right submandibular mass. A right Level II neck mass and mediastinal LN enlargement were confirmed on the pharynx and chest CT scan. Multiple subepithelial masses with central ulceration and erosion were observed in the corpus and fundus on the esophagogastroduodenoscopy and in the right colon on the colonoscopy. The histopathology findings were the same in each tissue biopsied from the stomach, colon, and right neck lymph nodes. Langerhans cells with classical reniform nuclei and prominent eosinophils invaded the normal glands, and S100 and CD1a were positive in the immunohistochemical stain. Gastrointestinal involvement of LCH in adults is rare, asymptomatic,and can involve multiple digestive organs simultaneously, so upper endoscopy and colonoscopy should be considered for a diagnosis.

Purpose: This study aimed to present our experiences with a precise surgical strategy for sacrectomy. Materials and Methods: This study comprised a retrospective review of 16 patients (6 males and 10 females) who underwent sacrectomy from 2011 to 2019. The average age was 42.4 years old, and the mean follow-up period was 40.8 months. Clinical data, including age, sex, history, pathology, radiographs, surgical approaches, onset of recurrence, and prognosis, were analyzed. Results: The main preoperative symptom was non-specific local pain. Nine patients (56%) complained of bladder and bowel symptoms. All patients required spinopelvic reconstruction after sacrectomy. Three patients, one high, one middle, and one hemisacrectomy, underwent spinopelvic reconstruction. The pathology findings of tumors varied (chordoma, n=7; nerve sheath tumor, n=4; giant cell tumor, n=3, etc.). Adjuvant radiotherapy was performed for 5 patients, chemotherapy for three, and combined chemoradiotherapy for another three. Six patients (38%) reported postoperative motor weakness, and newly postoperative bladder and bowel symptoms occurred in 5 patients. Three patients (12%) experienced recurrence and expired. Conclusion In surgical resection of sacral tumors, the surgical approach depends on the size, location, extension, and pathology of the tumors. The recommended treatment option for sacral tumors is to remove as much of the tumor as possible. The level of root sacrifice is a predicting factor for postoperative neurologic functional impairment and the potential for morbidity. Pre-operative angiography and embolization are recommended to prevent excessive bleeding during surgery. Spinopelvic reconstruction must be considered following a total or high sacrectomy or sacroiliac joint removal.

Background: The advancement of treatment with direct-acting antiviral (DAA) agents has improved the cure rate of hepatitis C virus (HCV) infection close to 100%. The aim of our study was to assess the real-world effectiveness and safety of DAA regimens for the treatment of patients with chronic HCV genotype 2. Methods: We retrospectively analyzed the clinical data of patients treated with sofosbuvir plus ribavirin (SOF + RBV) or glecaprevir/pibrentasvir (G/P) for chronic HCV genotype 2 infection at seven university hospitals in the Korean southeast region. Results: SOF + RBV therapy produced an 89% and 98.3% sustained virologic response 12 week (SVR12) after treatment completion in the full analysis set and per-protocol set, respectively, and the corresponding values for G/P therapy were 89.5% and 99.2%, respectively. The difference between the treatments was probably because 6.2% (59/953) of patients in the SOF + RBV group did not complete the treatment and 9.8% (14/143) in the G/P group did not test HCV RNA after treatment completion. Adverse events (A/Es) were reported in 59.7% (569/953) and 25.9% (37/143) of the SOF + RBV and G/P groups, respectively. In the SOF + RBV group, 12 (1.26%) patients discontinued treatment owing to A/Es, whereas no patients discontinued treatment because of A/Es in the G/P group. Conclusion In both treatment groups, SVR was high when treatment was completed.However, there was a high dropout rate in the SOF + RBV group, and the dropout analysis showed that these were patients with liver cirrhosis (LC; 43/285, 15.1%), especially those with decompensated LC (12/32, 37.5%). Therefore, an early initiation of antiviral therapy is recommended for a successful outcome before liver function declines. Furthermore, patients with decompensated LC who are considered candidates for SOF + RBV treatment should be carefully monitored to ensure that their treatment is completed, especially those with low hemoglobin and high alanine transaminase.

Objective: : To investigate the radiographic characteristics of the uppermost instrumented vertebrae (UIV) and UIV+1 compression fractures that are predictive of revision surgery following long-segment spinal fixation. Methods: : A total 27 patients who presented newly developed compression fracture at UIV, UIV+1 after long segment spinal fixation (minimum 5 vertebral bodies, lowest instrumented vertebra of L5 or distal) were reviewed retrospectively. Patients were divided into two groups according to following management : revisional surgery (group A, n=13) and conservative care (group B, n=14). Pre- and postoperative images, and images taken shortly before and after the occurrence of fracture were evaluated for radiologic characteristics Results: : Despite similar degrees of surgical correction of deformity, the fate of the two groups with proximal junctional compression fractures differed. Immediately after the fracture, the decrement of adjacent disc height in group A (32.3±7.6 mm to 23.7±8.4 mm, Δ=8.5±6.9 mm) was greater than group B (31.0±13.9 mm to 30.1±15.5 mm, Δ=0.9±2.9 mm, p=0.003). Pre-operative magnetic resonance imaging indicated that group A patients have a higher grade of disc degeneration adjacent to fractured vertebrae compared to group B (modified Pfirrmann grade, group A : 6.10±0.99, group B : 4.08±0.90, p=0.004). Binary logistic regression analysis indicated that decrement of disc height was the only associated risk factor for future revision surgery (odds ratio, 1.891; 95% confidence interval, 1.121–3.190; p=0.017). Conclusion : Proximal junctional vertebral compression fractures with greater early-stage decrement of adjacent disc height were associated with increased risk of future neurological deterioration and necessity of revision. The condition of adjacent disc degeneration should be considered regarding severity and revision rate of proximal junctional kyphosis/proximal junction failures.