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Se-Jun Park, Chong-Suh Lee, Jin-Sung Park, Tae-Hoon Yum, Tae Soo Shin, Ji-Woo Chang, and Keun-Ho Lee

OBJECTIVE

Iliac screw fixation and anterior column support are highly recommended to prevent lumbosacral pseudarthrosis after long-level adult spinal deformity (ASD) surgery. Despite modern instrumentation techniques, a considerable number of patients still experience nonunion at the lumbosacral junction. However, most previous studies evaluating nonunion relied only on plain radiographs and only assessed when the implant failures occurred. Therefore, using CT, it is important to know the prevalence after iliac fixation and to evaluate risk factors for nonunion at L5–S1.

METHODS

Seventy-seven patients who underwent ≥ 4-level fusion to the sacrum using iliac screws for ASD and completed a 2-year postoperative CT scan were included in the present study. All L5–S1 segments were treated by interbody fusion. Lumbosacral fusion status was evaluated on 2-year postoperative CT scans using Brantigan, Steffee, and Fraser criteria. Risk factors for nonunion were analyzed using patient, surgical, and radiographic factors. The metal failure and its association with fusion status at L5–S1 were evaluated.

RESULTS

Of the 77 patients, 12 (15.6%) showed nonunion at the lumbosacral junction on the 2-year CT scans. Multivariate analysis using logistic regression revealed that only higher American Society of Anesthesiologists (ASA) grade was a risk factor for nonunion (OR 25.6, 95% CI 3.196–205.048, p = 0.002). There were no radiographic parameters associated with fusion status at L5–S1. Lumbosacral junction rod fracture occurred more frequently in patients with nonunion than in patients with fusion (33.3% vs 6.2%, p = 0.038).

CONCLUSIONS

Although iliac screw fixation and anterior column support have been performed to prevent lumbosacral nonunion during ASD surgery, 15.6% of patients still showed nonunion on 2-year postoperative CT scans. High ASA grade was a significant risk factor for nonunion. Rod fracture between L5 and S1 occurred more frequently in the nonunion group.

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Myung Ji Kim, So Hee Park, Kyung Won Chang, Yuhee Kim, Jing Gao, Maya Kovalevsky, Itay Rachmilevitch, Eyal Zadicario, Won Seok Chang, Hyun Ho Jung, and Jin Woo Chang

OBJECTIVE

Magnetic resonance imaging–guided focused ultrasound (MRgFUS) provides real-time monitoring of patients to assess tremor control and document any adverse effects. MRgFUS of the ventral intermediate nucleus (VIM) of the thalamus has become an effective treatment option for medically intractable essential tremor (ET). The aim of this study was to analyze the correlations of clinical and technical parameters with 12-month outcomes after unilateral MRgFUS thalamotomy for ET to help guide future clinical treatments.

METHODS

From October 2013 to January 2019, data on unilateral MRgFUS thalamotomy from the original pivotal study and continued-access studies from three different geographic regions were collected. Authors of the present study retrospectively reviewed those data and evaluated the efficacy of the procedure on the basis of improvement in the Clinical Rating Scale for Tremor (CRST) subscore at 1 year posttreatment. Safety was based on the rates of moderate and severe thalamotomy-related adverse events. Treatment outcomes in relation to various patient- and sonication-related parameters were analyzed in a large cohort of patients with ET.

RESULTS

In total, 250 patients were included in the present analysis. Improvement was sustained throughout the 12-month follow-up period, and 184 (73.6%) of 250 patients had minimal or no disability due to tremor (CRST subscore < 10) at the 12-month follow-up. Younger age and higher focal temperature (Tmax) correlated with tremor improvement in the multivariate analysis (OR 0.948, p = 0.013; OR 1.188, p = 0.025; respectively). However, no single statistically significant factor correlated with Tmax in the multivariate analysis. The cutoff value of Tmax in predicting a CRST subscore < 10 was 55.8°C. Skull density ratio (SDR) was positively correlated with heating efficiency (β = 0.005, p < 0.001), but no significant relationship with tremor improvement was observed. In the low-temperature group, 1–3 repetitions to the right target with 52°C ≤ Tmax ≤ 54°C was sufficient to generate sustained tremor suppression within the investigated follow-up period. The high-temperature group had a higher rate of balance disturbances than the low-temperature group (p = 0.04).

CONCLUSIONS

The authors analyzed the data of 250 patients with the aim of improving practices for patient screening and determining treatment endpoints. These results may improve the safety, efficacy, and efficiency of MRgFUS thalamotomy for ET.

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Ji Hee Kim, Hyun Ho Jung, Jong Hee Chang, Jin Woo Chang, Yong Gou Park, and Won Seok Chang

Object

Intracranial chordomas and chondrosarcomas are histologically low-grade, locally invasive tumors that are reported to be similar in terms of anatomical location, clinical presentation, and radiological findings but different in terms of behavior and outcomes. The purpose of this study was to investigate and compare clinical outcomes after Gamma Knife surgery (GKS) for the treatment of intracranial chordoma and chondrosarcoma.

Methods

The authors conducted a retrospective review of the results of radiosurgical treatment of intracranial chordomas and chondrosarcomas. They enrolled patients who had undergone GKS for intracranial chordoma or chondrosarcoma at the Yonsei Gamma Knife Center, Yonsei University College of Medicine, from October 2000 through June 2007. Analyses included only patients for whom the disease was pathologically diagnosed before GKS and for whom more than 5 years of follow-up data after GKS were available. Rates of progression-free survival and overall survival were analyzed and compared according to tumor pathology. Moreover, the association between tumor control and the margin radiation dose to the tumor was analyzed, and the rate of tumor volume change after GKS was quantified.

Results

A total of 10 patients were enrolled in this study. Of these, 5 patients underwent a total of 8 sessions of GKS for chordoma, and the other 5 patients underwent a total of 7 sessions of GKS for chondrosarcoma. The 2- and 5-year progression-free survival rates for patients in the chordoma group were 70% and 35%, respectively, and rates for patients in the chondrosarcoma group were 100% and 80%, respectively (log-rank test, p = 0.04). The 2- and 5-year overall survival rates after GKS for patients in the chordoma group were 87.5% and 72.9%, respectively, and rates for patients in the chondrosarcoma group were 100% and 100%, respectively (log-rank test, p = 0.03). The mean rates of tumor volume change 2 years after radiosurgery were 79.64% and 39.91% for chordoma and chondrosarcoma, respectively (p = 0.05). No tumor progression was observed when margin doses greater than 16 Gy for chordoma and 14 Gy for chondrosarcoma were prescribed.

Conclusions

Outcomes after GKS were more favorable for patients with chondrosarcoma than for those with chordoma. The data also indicated that at 2 years after GKS, the rate of volume change is significantly higher for chordomas than for chondrosarcomas. The authors conclude that radiosurgery with a margin dose of more than 16 Gy for chordomas and more than 14 Gy for chondrosarcomas seems to enhance local tumor control with relatively few complications. Further studies are needed to determine the optimal dose of GKS for patients with intracranial chordoma or chondrosarcoma.

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Ji Woong Oh, Kyoung Su Sung, Ju Hyung Moon, Eui Hyun Kim, Won Seok Chang, Hyun Ho Jung, Jin Woo Chang, Yong Gou Park, Sun Ho Kim, and Jong Hee Chang

OBJECTIVE

This study investigated long-term follow-up data on the combined pituitary function test (CPFT) in patients who had undergone transsphenoidal surgery (TSS) for nonfunctioning pituitary adenoma (NFPA) to determine the clinical parameters indicative of hypopituitarism following postoperative Gamma Knife surgery (GKS).

METHODS

Between 2001 and 2015, a total of 971 NFPA patients underwent TSS, and 76 of them (7.8%) underwent postoperative GKS. All 76 patients were evaluated with a CPFT before and after GKS. The hormonal states were analyzed based on the following parameters: relevant factors before GKS (age, sex, extent of resection, pre-GKS hormonal states, time interval between TSS and GKS), GKS-related factors (tumor volume; radiation dose to tumor, pituitary stalk, and normal gland; distance between tumor and stalk), and clinical outcomes (tumor control rate, changes in hormonal states, need for hormone-related medication due to hormonal changes).

RESULTS

Of the 971 NFPA patients, 797 had gross-total resection (GTR) and 174 had subtotal resection (STR). Twenty-five GTR patients (3.1%) and 51 STR patients (29.3%) underwent GKS. The average follow-up period after GKS was 53.5 ± 35.5 months, and the tumor control rate was 96%. Of the 76 patients who underwent GKS, 23 were excluded due to pre-GKS panhypopituitarism (22) or loss to follow-up (1). Hypopituitarism developed in 13 (24.5%) of the remaining 53 patients after GKS. A higher incidence of post-GKS hypopituitarism occurred in the patients with normal pre-GKS hormonal states (41.7%, 10/24) than in the patients with abnormal pre-GKS hormonal states (10.3%, 3/29; p = 0.024). Target tumor volume (4.7 ± 3.9 cm3), distance between tumor and pituitary stalk (2.0 ± 2.2 mm), stalk dose (cutoffs: mean dose 7.56 Gy, maximal dose 12.3 Gy), and normal gland dose (cutoffs: maximal dose 13.9 Gy, minimal dose 5.25 Gy) were factors predictive of post-GKS hypopituitarism (p < 0.05).

CONCLUSIONS

This study analyzed the long-term follow-up CPFT data on hormonal changes in NFPA patients who underwent GKS after TSS. The authors propose a cutoff value for the radiation dose to the pituitary stalk and normal gland for the prevention of post-GKS hypopituitarism.

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Ji Hoon Phi, Jung Won Choi, Moon-Woo Seong, Tackeun Kim, Youn Joo Moon, Joongyub Lee, Eun Jung Koh, Seul Ki Ryu, Tae Hee Kang, Jae Seung Bang, Chang Wan Oh, Sung Sup Park, Ji Yeoun Lee, Kyu-Chang Wang, and Seung-Ki Kim

OBJECTIVE

In a minority of patients with neurofibromatosis Type 1 (NF-1), cerebral vasculopathy reminiscent of moyamoya disease develops. This phenomenon is called moyamoya syndrome (MMS), but there are no known risk factors for the prediction of MMS in NF-1 patients. Polymorphism of the RNF213 gene has exhibited strong associations with familial and sporadic moyamoya disease and other cerebral vasculopathies. The aim of this study is to find whether the RNF213 c.14576G>A variant is associated with MMS development in the NF-1 population or not.

METHODS

The MMS group included 16 NF-1 patients with documented MMS. The control group consisted of 97 NF-1 patients without MMS. Genomic DNA samples were obtained from the saliva or blood of both groups, and the presence of the RNF213 c.14576G>A variant was assessed by Sanger sequencing.

RESULTS

In the MMS group, 3 patients had the RNF213 c.14576G>A variant (18.7%), whereas no patients with this genetic variation were observed in the control group (0%). There was a meaningful association between the RNF213 c.14576G>A variant and MMS development (p = 0.0024). The crude odds ratio was calculated as 50.57 (95% CI 1.57–1624.41). All 3 patients with MMS and the c.14576G>A variant were diagnosed with MMS at an early age and had bilateral involvement.

CONCLUSIONS

The RNF213 c.14576G>A variant is more common in NF-1 patients who develop MMS than in NF-1 patients without MMS. This variant might be a susceptibility gene for the NF-1–moyamoya connection.

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So Hee Park, Myung Ji Kim, Hyun Ho Jung, Won Seok Chang, Hyun Seok Choi, Itay Rachmilevitch, Eyal Zadicario, and Jin Woo Chang

OBJECTIVE

Glioblastoma (GBM) remains fatal due to the blood-brain barrier (BBB), which interferes with the delivery of chemotherapeutic agents. The purpose of this study was to evaluate the safety and feasibility of repeated disruption of the BBB (BBBD) with MR-guided focused ultrasound (MRgFUS) in patients with GBM during standard adjuvant temozolomide (TMZ) chemotherapy.

METHODS

This study was a prospective, single-center, single-arm study. BBBD with MRgFUS was performed adjacent to the tumor resection margin on the 1st or 2nd day of the adjuvant TMZ chemotherapy at the same targets for 6 cycles. T2*-weighted/gradient echo (GRE) MRI was performed immediately after every sonication trial, and comprehensive MRI was performed at the completion of all sonication sessions. Radiological, laboratory, and clinical evaluations were performed 2 days before each planned BBBD.

RESULTS

From September 2018, 6 patients underwent 145 BBBD trials at various locations in the brain. The authors observed gadolinium-enhancing spots at the site of BBBD on T1-weighted MRI in 131 trials (90.3%) and 93 trials (64.1%) showed similar spots on T2*-weighted/GRE MRI. When the 2 sequences were combined, BBBD was observed in 134 targets (92.4%). The spots disappeared on follow-up MRI. There were no imaging changes related to BBBD and no clinical adverse effects during the 6 cycles.

CONCLUSIONS

This study is the first in which repetitive MRgFUS was performed at the same targets with a standard chemotherapy protocol for malignant brain tumor. BBBD with MRgFUS was performed accurately, repeatedly, and safely. Although a longer follow-up period is needed, this study allows for the possibility of other therapeutic agents that previously could not be used due to the BBB.

Clinical trial registration no.: NCT03712293 (clinicaltrials.gov)

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Young-Soo Kim, Ho-Yeol Zhang, Byung-Jin Moon, Kyung-Woo Park, Kyu-Yeul Ji, Won-Chang Lee, Kyu-Sung Oh, Gwon-Ui Ryu, and Daniel H. Kim

Object

The purpose of this study was to analyze the usefulness of the BioFlex, a Nitinol spring rod dynamic stabilization system, and the Nitinol shape memory loop (KIMPF-DI Fixing System) as a posterior dynamic stabilization system in surgery for low-back pain.

Methods

The 103 patients who underwent treatment with the BioFlex system were divided into two groups: Group 1, dynamic stabilization with or without posterior lumbar interbody fusion (PLIF); and Group 2, rigid fixation (PLIF + BioFlex system only). A total of 66 segments were treated with only the BioFlex system; in these the preoperative range of motion (ROM) was 10.0 ± 4.3°, which changed to 4.1 ± 1.9° after surgery. Adjacent-segment ROM changed from 8.4 ± 3.4° to 10.7 ± 3.2° in Group 1 and from 6.5 ± 3.2° to 10.5 ± 4.6° in Group 2 postoperatively. A total of 110 segments received both BioFlex and PLIF, with a fusion rate of 90.0%. The visual analog scale score for back pain improved from 7.3 ± 3.1 to 1.4 ± 1.8 in Group 1 and from 7.4 ± 2.4 to 2.1 ± 2.3 in Group 2. The Oswestry Disability Index improved from 35.2 ± 6.4 to 12.1 ± 4.5 in Group 1 and from 37.8 ± 5.7 to 13.6 ± 4.2 in Group 2. (The ROM and assessment scores expressed are the mean ± standard deviation.)

The 194 patients in whom Nitinol memory loops were implanted were analyzed based on the preoperative and 1-year postoperative ROM of each lumbar segment. The change of ROM in looped segments treated with PLIF was significantly reduced, but the change of ROM in looped segments without PLIF was not significant. The change of ROM at the segment adjacent to the loop was not significant, and the change of kyphosis reflected a slight recovery.

Conclusions

The Nitinol BioFlex dynamic stabilization system can achieve stabilization and simultaneously allow physiological movement, which can in turn decrease the degeneration of adjacent segments. When used with PLIF, the fusion rate can be expected to increase. The flexible Nitinol shape memory loop, a posterior dynamic stabilization device, is an adequate tension band that displays strength similar to the posterior ligamentous structures. In combination with PLIF at the main lesion, the BioFlex system or the Nitinol memory loop can provide posterior dynamic stabilization to the transitional upper or lower segments, enhance the fusion rate, reduce the adjacent-segment degeneration, and provide dynamic stabilization of the spine.