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Taek-Kyun Nam, Jung-Il Lee, Young-Jo Jung, Yong-Seok Im, Hee-Ye An, Do-Hyun Nam, Kwan Park and Jong-Hyun Kim

Object. This study was performed to evaluate the role of gamma knife surgery (GKS) in patients with a large number (four or more) of metastatic brain lesions.

Methods. The authors retrospectively reviewed the outcome in 130 patients who underwent GKS for metastatic lesions. Eighty-four patients presented with one to three lesions (Group A) and 46 presented with four or more lesions (Group B). The overall median survival time after GKS was 35 weeks. The median survival time in Group A (48 weeks) was significantly longer (p = 0.005) than the survival time in Group B (26 weeks). The recursive partitioning analysis (RPA) class was the only significant prognostic factor identified in multivariate analysis. The median survival for patients in RPA Classes I, II, and III was 72, 48, and 19 weeks, respectively, in Group A and 36 and 13 weeks for Classes II and III in Group B. The number of lesions, tumor volume, whole brain radiotherapy, primary tumor site, age, and sex did not affect survival significantly.

Conclusions. It is suggested that GKS provides an increase in survival time even in patients with a large number (four or more) of metastatic lesions. Concerning the selection of patients for GKS, RPA class should be considered as the most important factor and multiplicity of the lesions alone should not be a reason for withholding GKS.

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Doo-Sik Kong, Do-Hyun Nam, Jung-Il Lee, Kwan Park and Jong Hyun Kim

Object

The authors conducted a retrospective study to evaluate the efficacy of Gamma Knife surgery (GKS) followed by radiotherapy for the treatment of unresectable glioblastomas multiforme (GBMs) on patient survival and quality of life.

Methods

A total of 19 patients with unresectable GBMs located in eloquent areas of the brain were eligible for this study. Beginning in January 2002, 10 patients underwent GKS followed by fractionated radiotherapy. Nine patients who had undergone radiotherapy alone after biopsy-proven diagnosis served as the control group. The mean patient ages were 53 years and 56 years, respectively. Preoperative Karnofsky Performance Scale (KPS) scores were 80 (range 60–100) and 90 (range 50–100), respectively. The median margin dose for GKS was 12 Gy (9–16 Gy), and the total dose for radiotherapy was 60 Gy in 30 fractions. The mean follow-up duration was 7.2 months, the median patient survival time was 52 weeks (95% confidence interval [CI] 22–110.6 weeks) in the GKS group, and the median overall survival time was 28 weeks (95% CI 22.5–33.5 weeks) in the control group. The difference was not statistically significant (p = 0.0758). The estimated progression-free survival rate at 3 months was 75% in the GKS group and 45% in the control group (p = 0.082). The posttreatment KPS scores were either unchanged or improved in the GKS group, whereas it deteriorated by 20 or more points in six of nine patients of the control group (p = 0.004).

Conclusions

Gamma Knife surgery prior to radiotherapy may be helpful in preserving patients' daily activities in the adjuvant management of unresectable GBM.

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Byung Sup Kim, Yuil Kim, Doo-Sik Kong, Do-Hyun Nam, Jung-Il Lee, Yeon-Lim Suh and Ho Jun Seol

OBJECTIVE

The authors conducted this retrospective study to investigate the clinical outcomes of intracranial solitary fibrous tumor (SFT) and hemangiopericytoma (HPC), defined according to the 2016 WHO classification of central nervous system (CNS) tumors.

METHODS

Histopathologically proven intracranial SFT and HPC cases treated in the period from June 1996 to September 2014 were retrospectively reviewed and analyzed. Two neuropathologists reviewed pathological slides and regraded the specimens according to the 2016 WHO classification. Factors associated with progression-free survival (PFS) and overall survival (OS) were statistically evaluated with uni- and multivariate analyses.

RESULTS

The records of 47 patients—10 with SFT, 33 with HPC, and 4 with anaplastic HPC—were reviewed. A malignant transition from conventional SFT to WHO grade III SFT/HPC was observed in 2 cases, and 13 HPC cases were assigned grade III SFT/HPC. Mean and median follow-ups were 114.6 and 94.7 months, respectively (range 7.1–366.7 months). Gross-total resection (GTR) was significantly associated with longer PFS and OS (p = 0.012 for both), and adjuvant radiation therapy versus no such therapy led to significantly longer PFS (p = 0.018). Extracranial metastases to the liver, bone, lung, spine, and kidney occurred in 10 patients (21.3%). Grade III SFT/HPC was strongly correlated with the development of extracranial metastases (p = 0.031).

CONCLUSIONS

The 2016 WHO classification of CNS tumors reflected the different types of pathological malignant progression and clinical outcomes better than prior classifications. Gross-total resection should be the primary treatment goal in patients with SFT/HPC, regardless of the pathological grade, and radiation can be administered as adjuvant therapy for patients with SFT/HPC that shows an aggressive phenotype or that is not treated with GTR.

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Kyung Hwan Kim, So Jeong Kang, Jung-Won Choi, Doo-Sik Kong, Ho Jun Seol, Do-Hyun Nam and Jung-Il Lee

OBJECTIVE

This study aimed to verify the effect of proactive Gamma Knife surgery (GKS) in the treatment of asymptomatic meningioma compared with the natural course without any therapeutic intervention.

METHODS

From January 2006 to May 2017, 354 patients newly diagnosed with asymptomatic meningioma were reviewed and categorized into GKS (n = 153) and observation (n = 201) groups. Clinical and radiological progression rates were examined, and changes in volume were analyzed.

RESULTS

Clinical progression (i.e., clinician-judged progression), combining symptomatic progression (n = 43) and clinician-judged increase in size using images routinely acquired (n = 34), occurred in 4 patients (2.6%) and 73 patients (36.3%) in the GKS and observation groups, respectively (p < 0.001). The clinical progression-free survival (PFS) rates in the GKS and observation groups were 98.7% and 64.6%, respectively, at 5 years (p < 0.001), and 92.9% and 42.7%, respectively, at 10 years (p < 0.001). The radiological tumor control rate was 94.1% in the GKS group, and radiological progression was noted in 141 patients (70.1%) in the observation group. The radiological PFS rates in the GKS and observation groups were 94.4% and 38.5%, respectively, at 5 years (p < 0.001), and 88.5% and 7.9%, respectively, at 10 years (p < 0.001). Young age, absence of calcification, peritumoral edema, and high T2 signal intensity were correlated with clinical progression in the observation group. Volumetric analysis showed that untreated tumors gradually increased in size. However, GKS-treated tumors shrank gradually, although transient volume expansion was observed in the first 6 months. Adverse events developed in 26 of the 195 GKS-treated patients (13.3%), including 1 (0.5%) major event requiring microsurgery due to severe edema after GKS. Peritumoral edema was related to the development of adverse events (p = 0.004).

CONCLUSIONS

Asymptomatic meningioma is a benign disease; however, nearly two-thirds of patients experience tumor growth and one-third of untreated patients eventually require neurosurgical interventions during watchful waiting. GKS can control tumors clinically and radiologically with high probability. Although the risk of transient adverse events exists, proactive GKS may be a reasonable treatment option when there are no comorbidities limiting life expectancy.

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Chiman Jeon, Kyung Rae Cho, Jung Won Choi, Doo-Sik Kong, Ho Jun Seol, Do-Hyun Nam and Jung-Il Lee

OBJECTIVE

This study was performed to evaluate the role of Gamma Knife radiosurgery (GKRS) as a primary treatment for central neurocytomas (CNs).

METHODS

The authors retrospectively assessed the treatment outcomes of patients who had undergone primary treatment with GKRS for CNs in the period between December 2001 and December 2018. The diagnosis of CN was based on findings on neuroimaging studies. The electronic medical records were retrospectively reviewed for additional relevant preoperative data, and clinical follow-up data had been obtained during office evaluations of the treated patients. All radiographic data were reviewed by a dedicated neuroradiologist.

RESULTS

Fourteen patients were treated with GKRS as a primary treatment for CNs in the study period. Seven patients (50.0%) were asymptomatic at initial presentation, and 7 (50.0%) presented with headache. Ten patients (71.4%) were treated with GKRS after the diagnosis of CN based on characteristic MRI findings. Four patients (28.6%) initially underwent either stereotactic or endoscopic biopsy before GKRS. The median tumor volume was 3.9 cm3 (range 0.46–18.1 cm3). The median prescription dose delivered to the tumor margin was 15 Gy (range 5.5–18 Gy). The median maximum dose was 30 Gy (range 11–36 Gy). Two patients were treated with fractionated GKRS, one with a prescription dose of 21 Gy in 3 fractions and another with a dose of 22 Gy in 4 fractions. Control of tumor growth was achieved in all 14 patients. The median volume reduction was 26.4% (range 0%–78.3%). Transient adverse radiation effects were observed in 2 patients but resolved with improvement in symptoms. No recurrences were revealed during the follow-up period, which was a median of 25 months (range 12–89 months).

CONCLUSIONS

Primary GKRS for CNs resulted in excellent tumor control rates without recurrences. These results suggest that GKRS may be a viable treatment option for patients with small- to medium-sized or incidental CNs.

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Jung-Il Lee, Do-Hyun Nam, Jong Soo Kim, Seung-Chyul Hong, Hyung-Jin Shin, Kwan Park, Whan Eoh, Yeon-Lim Suh and Jong Hyun Kim

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Doo-Sik Kong, Do-Hyun Nam, Jung-Il Lee, Kwan Park, Jong Hyun Kim and Hyung Jin Shin

Object

It is important to differentiate growing teratoma syndrome (GTS) from tumor recurrence in the setting of an enlarging residual mass present after treatment of intracranial germ cell tumors (GCTs). The aim of this study was to determine the incidence of intracranial GTS and present its clinical manifestations in detail.

Methods

The authors performed a retrospective cohort study of 52 consecutive patients with newly diagnosed intracranial GCTs who presented between January 2000 and December 2006. The records were screened to identify a study cohort in which all patients had regrowing tumor mass despite normalization of tumor markers during or after treatment of GCTs.

Results

In 6 (11.5%) of 52 patients the pathological diagnosis was GTS. The median patient age at diagnosis was 14.5 years (range 2 months–17 years), and the primary tumors included 4 mixed GCTs and 2 immature teratomas. After second-look surgery, histological testing revealed the lesions to be mature teratoma in all patients. Three of 6 patients subsequently underwent radiation therapy and 1 patient received additional chemotherapy for spinal seeding.

Conclusions

In enlarging residual masses after treatment of intracranial GCTs, GTS should be kept in mind in the differential diagnosis of tumor recurrence especially if there is a radiographic mismatch with serum marker test results. If technically feasible, second-look surgery may be necessary for an accurate diagnosis.

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Kyung-Il Jo, Yong Seok Im, Doo-Sik Kong, Ho Jun Seol, Do-Hyun Nam, Yoon-Duck Kim and Jung-Il Lee

Object

The goal of this study was to investigate the safety and efficacy of multisession Gamma Knife surgery (GKS) in the treatment of benign orbital tumors.

Methods

Twenty-three patients who retained their vision despite having tumors touching their optic nerve were treated with multisession (4-fraction) GKS. The median tumor volume was 2800 mm3 (range 211–10,800 mm3), and the median cumulative margin dose was 20 Gy (range 18–22 Gy).

Results

The median clinical follow-up duration in these patients was 38 months (range 9–74 months). No patient experienced tumor progression in this study. In particular, a higher degree of tumor shrinkage was found in the 7 patients with cavernous hemangiomas than in patients with other types of lesions (p < 0.05). Of the 23 patients whose preoperative vision was preserved, 11 showed improvement in visual acuity and/or visual field and 12 showed stable visual acuity. No GKS-related adverse events were noted during or after treatment.

Conclusions

Multisession radiosurgery using the Gamma Knife may be a good strategy for tumors in direct contact with the optic nerve. A cumulative margin dose of up to 22 Gy delivered in 4 sessions is safe for preservation of visual function with a high probability of tumor control.

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Chiman Jeon, Chang-Ki Hong, Kyung In Woo, Sang Duk Hong, Do-Hyun Nam, Jung-Il Lee, Jung Won Choi, Ho Jun Seol and Doo-Sik Kong

OBJECTIVE

Tumors involving Meckel’s cave remain extremely challenging because of the surrounding complex neurovascular structures and deep-seated location. The authors investigated a new minimal-access technique using the endoscopic transorbital approach (eTOA) through the superior eyelid crease to Meckel’s cave and middle cranial fossa lesions and reviewed the most useful surgical procedures and pitfalls of this approach.

METHODS

Between September 2016 and January 2018, the authors performed eTOA in 9 patients with tumors involving Meckel’s cave and the middle cranial fossa. The lesions included trigeminal schwannoma in 4 patients, meningioma in 2 patients, metastatic brain tumor in 1 patient, chondrosarcoma in 1 patient, and dermoid cyst in 1 patient. In 7 of the 9 patients, eTOA alone was performed, while the other 2 patients underwent a combined eTOA and endoscopic endonasal approach or retrosigmoid craniotomy. Data including details of surgical techniques and clinical outcomes were recorded.

RESULTS

Gross-total resection was performed in 7 of the 9 patients (77.8%). Four patients underwent extended eTOA (with lateral orbital rim osteotomy). Drilling of the trapezoid sphenoid floor, a middle fossa “peeling” technique, and full visualization of Meckel’s cave were applied to approach the lesions. Tumors were exposed and removed extradurally in 3 patients and intradurally in 6 patients. There was no postoperative CSF leak.

CONCLUSIONS

The eTOA affords a direct route to access Meckel’s cave and middle cranial fossa lesions. With experience, this novel approach can be successfully applied to selected skull base lesions. To achieve successful removal of the tumor, emphasis should be placed on the importance of adequately removing the greater sphenoid wing and vertical crest. However, because of limited working space eTOA may not be an ideal approach for posterior fossa lesions.

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Doo-Sik Kong, Chang-Ki Hong, Sang Duk Hong, Do-Hyun Nam, Jung-Il Lee, Ho Jun Seol, Jiwoong Oh, Dong Gyu Kim and Yong Hwy Kim

OBJECTIVE

The endoscopic endonasal approach (EEA) and the transcranial approach (TCA) are good options for the treatment of tuberculum sellae (TS) meningiomas. The objective of this study was to identify the key anatomical features in TS meningiomas and compare the two surgical approaches.

METHODS

The authors retrospectively reviewed clinical data in 178 patients with TS meningiomas treated at 3 institutions between January 2010 and July 2016. Patients with tumors encasing the internal carotid artery or anterior cerebral artery or involving the anterior clinoid process or cavernous sinus were excluded. Tumors were classified as high-lying or low-lying based on their location, and involvement of the optic canal was evaluated. The surgical outcomes of EEA and TCA were analyzed according to the relevant anatomical features.

RESULTS

During the study period, 84 patients underwent EEA and 94 patients underwent TCA. Based on preoperative MR images, 43 (24.2%) meningiomas were classified as high-lying tumors, 126 (70.8%) as low-lying, and 9 (5.0%) as nonspecific. Gross-total resection (GTR) was performed in 145 patients (81.5%); the GTR rate did not differ significantly between the EEA and TCA groups. Of 157 patients with preoperative visual disturbance, 140 had improved or stable vision postoperatively. However, 17 patients (9.6%) experienced some visual deterioration after surgery. The TCA group had a worse visual outcome than the EEA group in patients with preoperative optic canal involvement (77.6% vs 93.2%, p = 0.019), whereas there was no significant difference in visual outcome based on whether tumors were high-lying or low-lying.

CONCLUSIONS

The results of this study support EEA over TCA, at least with respect to visual improvement with acceptable complications, although TCA is still an effective approach for TS meningioma.