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Eui Hyun Kim, Jung Yong Ahn, and Sun Ho Kim

Object

The transcranial approach has been the standard technique for removal of craniopharyngiomas for several decades. However, many reports of successful suprasellar craniopharyngioma removal accomplished using extended transsphenoidal surgery (TSS) have recently been published. In the present study, the authors describe their technique and the outcomes of removal of suprasellar craniopharyngiomas aided by the use of an operating microscope and an endoscope concurrently during extended TSS.

Methods

Between 1999 and 2008, 18 patients with suprasellar craniopharyngiomas underwent TSS. Tumors that adhered to the optic nerve were safely dissected, and fine perforating vessels were precisely preserved with the aid of a magnified, detailed microscopic view. Portions of the tumor that could not be properly visualized with the microscope were visualized with the endoscope.

Results

Total resection was achieved in all patients, and all visual symptoms improved. Preoperative hypopituitarism improved in 2 patients but persisted postoperatively in 15 patients (hormonal outcome was not available in 1 patient). Diabetes insipidus was present in 16 patients postoperatively. Cerebrospinal fluid leakage developed in 3 patients in the conventional fascia lata graft group, whereas no CSF leakage occurred after the dural suture technique with a fascia lata graft was introduced. This technique could be more precisely applied when using a microscopic view. Tumor recurrence was documented for 1 patient 2 years after surgery.

Conclusions

The authors achieved good results by using extended TSS for the removal of suprasellar craniopharyngiomas. Endoscopy-assisted microscopic extended TSS harnesses the advantages of a microscope as well as those of an endoscope. Surgeons should consider using the advantages of both surgical modalities to achieve the best result possible.

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Na Young Jung, Chang Kyu Park, Won Seok Chang, Hyun Ho Jung, and Jin Woo Chang

OBJECTIVE

Although neurosurgical procedures are effective treatments for controlling involuntary tremor in patients with essential tremor (ET), they can cause cognitive decline, which can affect quality of life (QOL). The purpose of this study is to assess the changes in the neuropsychological profile and QOL of patients following MR-guided focused ultrasound (MRgFUS) thalamotomy for ET.

METHODS

The authors prospectively analyzed 20 patients with ET who underwent unilateral MRgFUS thalamotomy at their institute in the period from March 2012 to September 2014. Patients were regularly evaluated with the Clinical Rating Scale for Tremor (CRST), neuroimaging, and cognition and QOL measures. The Seoul Neuropsychological Screening Battery was used to assess cognitive function, and the Quality of Life in Essential Tremor Questionnaire (QUEST) was used to evaluate the postoperative change in QOL.

RESULTS

The total CRST score improved by 67.3% (from 44.75 ± 9.57 to 14.65 ± 9.19, p < 0.001) at 1 year following MRgFUS thalamotomy. Mean tremor scores improved by 68% in the hand contralateral to the thalamotomy, but there was no significant improvement in the ipsilateral hand. Although minimal cognitive decline was observed without statistical significance, memory function was much improved (p = 0.031). The total QUEST score also showed the same trend of improving (64.16 ± 17.75 vs 27.38 ± 13.96, p < 0.001).

CONCLUSIONS

The authors report that MRgFUS thalamotomy had beneficial effects in terms of not only tremor control but also safety for cognitive function and QOL. Acceptable postoperative changes in cognition and much-improved QOL positively support the clinical significance of MRgFUS thalamotomy as a new, favorable surgical treatment in patients with ET.

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Hyun Ho Jung, Won Seok Chang, Itay Rachmilevitch, Tal Tlusty, Eyal Zadicario, and Jin Woo Chang

OBJECT

The authors report different MRI patterns in patients with essential tremor (ET) or obsessive-compulsive disorder (OCD) after transcranial MR-guided focused ultrasound (MRgFUS) and discuss possible causes of occasional MRgFUS failure.

METHODS

Between March 2012 and August 2013, MRgFUS was used to perform unilateral thalamotomy in 11 ET patients and bilateral anterior limb capsulotomy in 6 OCD patients; in all patients symptoms were refractory to drug therapy. Sequential MR images were obtained in patients across a 6-month follow-up period.

RESULTS

For OCD patients, lesion size slowly increased and peaked 1 week after treatment, after which lesion size gradually decreased. For ET patients, lesions were visible immediately after treatment and markedly reduced in size as time passed. In 3 ET patients and 1 OCD patient, there was no or little temperature rise (i.e., < 52°C) during MRgFUS. Successful and failed patient groups showed differences in their ratio of cortical-to-bone marrow thickness (i.e., skull density).

CONCLUSIONS

The authors found different MRI pattern evolution after MRgFUS for white matter and gray matter. Their results suggest that skull characteristics, such as low skull density, should be evaluated prior to MRgFUS to successfully achieve thermal rise.

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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 Ho Han, Dong Gyu Kim, Hyun-Tai Chung, Chul-Kee Park, Sun Ha Paek, Jeong Eun Kim, Hee-Won Jung, and Dae Hee Han

Object

In this paper the authors analyzed the clinical and neuroimaging outcomes of patients with cerebral arteriovenous malformations (AVMs) after Gamma Knife surgery (GKS), focusing on the analysis of the radiation injury rate depending on the AVM volume.

Methods

Between 1997 and 2004, 277 consecutive patients with cerebral AVMs were treated with GKS. Of these patients, 218 were followed up for ≥ 2 years. The mean age was 31 ± 15 years, the median AVM volume was 3.4 cm3 (range 0.17–35.2 cm3), the median marginal dose was 18.0 Gy (range 10.0–25.0 Gy), and the mean follow-up duration was 44 ± 20 months. The authors reduced the prescription dose by various amounts, depending on the AVM volume and location as prescribed in the classic guideline to avoid irreversible radiation injuries.

Results

The angiographic obliteration rate was 66.4% overall, and it was 81.7, 53.1, and 12.5% for small, medium, and large AVMs, respectively. The overall annual bleeding rate was 1.9%. The annual bleeding rate was 0.44 and 4.64% for small and large AVMs, respectively. Approximately 20% of the patients showed severe postradiosurgery imaging (PRI) changes. The rate of PRI change was 11.4, 33.3, and 9.5% for small, medium, and large AVM volume groups, respectively, and a permanent radiation injury developed in 5.1% of patients.

Conclusions

By using the reduced dose from what is usually prescribed, the authors were able to obtain outcomes in small AVMs that were comparable to the outcomes described in previous reports. However, medium AVMs appear to still be at risk for adverse radiation effects. Last, in large AVMs, the authors were able to attain a tolerable rate of radiation injury; however, the clinical outcomes were quite disappointing following administration of a reduced dose of GKS for large AVMs.

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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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Kyung Hwan Kim, Doo-Sik Kong, Kyung Rae Cho, Min Ho Lee, Jung-Won Choi, Ho Jun Seol, Sung Tae Kim, Do-Hyun Nam, and Jung-Il Lee

OBJECTIVE

Fractionated Gamma Knife radiosurgery (GKS) represents a feasible option for patients with large brain metastases (BM). However, the dose-fractionation scheme balanced between local control and radiation-induced toxicity remains unclear. Therefore, the authors conducted a dose-escalation study using fractionated GKS as the primary treatment for large (> 3 cm) BM.

METHODS

The exclusion criteria were more than 3 lesions, evidence of leptomeningeal disease, metastatic melanoma, poor general condition, and previously treated lesions. Patients were randomized to receive 24, 27, or 30 Gy in 3 fractions (8, 9, or 10 Gy per fraction, respectively). The primary endpoint was the development of radiation necrosis assessed by a neuroradiologist blinded to the study. The secondary endpoints included the local progression-free survival (PFS) rate, change in tumor volume, development of distant intracranial progression, and overall survival.

RESULTS

Between September 2016 and April 2018, 60 patients were eligible for the study, with 46 patients (15, 17, and 14 patients in the 8-, 9-, and 10-Gy groups, respectively) available for analysis. The median follow-up duration was 9.6 months (range 2.5–25.1 months). The 6-month estimated cumulative incidence of radiation necrosis was 0% in the 8-Gy group, 13% (95% confidence interval [CI] 0%–29%) in the 9-Gy group, and 37% (95% CI 1%–58%) in the 10-Gy group. Being in the 10-Gy group was a significant risk factor for the development of radiation necrosis (p = 0.047; hazard ratio [HR] 7.2, 95% CI 1.1–51.4). The 12-month local PFS rates were 65%, 80%, and 75% in the 8-, 9-, and 10-Gy groups, respectively. Being in the 8-Gy group was a risk factor for local treatment failure (p = 0.037; HR 2.5, 95% CI 1.1–29.6). The mean volume change from baseline was a 47.5% decrease in this cohort. Distant intracranial progression and overall survival did not differ among the 3 groups.

CONCLUSIONS

In this dose-escalation study, 27 Gy in 3 fractions appeared to be a relevant regimen of fractionated GKS for large BM because 30 Gy in 3 fractions resulted in unacceptable toxicities and 24 Gy in 3 fractions was associated with local treatment failure.

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

OBJECTIVE

Fractionated Gamma Knife surgery (FGKS) has recently been used to treat large brain metastases. However, little is known about specific volume changes of lesions during the course of treatment. The authors investigated short-term volume changes of metastatic lesions during FGKS.

METHODS

The authors analyzed 33 patients with 40 lesions who underwent FGKS for intracranial metastases of non–small-cell lung cancer (NSCLC; 25 patients with 32 lesions) and breast cancer (8 patients with 8 lesions). FGKS was performed in 3–5 fractions. Baseline MRI was performed before the first fraction. MRI was repeated after 1 or 2 fractions. Adaptive planning was executed based on new images. The median prescription dose was 8 Gy (range 6–10 Gy) with a 50% isodose line.

RESULTS

On follow-up MRI, 18 of 40 lesions (45.0%) showed decreased tumor volumes (TVs). A significant difference was observed between baseline (median 15.8 cm3) and follow-up (median 14.2 cm3) volumes (p < 0.001). A conformity index was significantly decreased when it was assumed that adaptive planning was not implemented, from baseline (mean 0.96) to follow-up (mean 0.90, p < 0.001). The average reduction rate was 1.5% per day. The median follow-up duration was 29.5 weeks (range 9–94 weeks). During the follow-up period, local recurrence occurred in 5 lesions.

CONCLUSIONS

The TV showed changes with a high dose of radiation during the course of FGKS. Volumetric change caused a significant difference in the clinical parameters. It is expected that adaptive planning would be helpful in the case of radiosensitive tumors such as NSCLCs or breast cancer to ensure an adequate dose to the target area and reduce unnecessary exposure of normal tissue to radiation.

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

OBJECTIVE

Orbital tumors are often surgically challenging because they require an extensive fronto-temporo-orbital zygomatic approach (FTOZ) and a multidisciplinary team approach to provide the best outcomes. Recently, minimally invasive endoscopic techniques via a transorbital superior eyelid approach (ETOA) or endoscopic endonasal approach (EEA) have been proposed as viable alternatives to transcranial approaches for orbital tumors. In this study, the authors investigated the feasibility of 360° circumferential access to orbital tumors via both ETOA and EEA.

METHODS

Between April 2014 and June 2019, 16 patients with orbital tumors underwent either ETOA or EEA at the authors’ institution. Based on the neuro-topographic “four-zone model” of the orbit with its tumor epicenter around the optic nerve in the coronal plane, ETOA (n = 10, 62.5%) was performed for tumors located predominantly superolateral to the nerve and EEA (n = 6, 37.5%) for those located predominantly inferomedial to the nerve. Eight patients (50%) presented with intraconal tumors and 8 (50%) with extraconal ones. The orbital tumors included orbital schwannoma (n = 6), cavernous hemangioma (n = 2), olfactory groove meningioma (n = 1), sphenoorbital meningioma (n = 1), chondrosarcoma (n = 1), trigeminal schwannoma (n = 1), metastatic osteosarcoma (n = 1), mature cystic teratoma (n = 1), sebaceous carcinoma (n = 1), and ethmoid sinus osteoma (n = 1). The clinical outcomes and details of surgical techniques were reviewed.

RESULTS

Gross-total resection was achieved in 12 patients (75%), near-total resection in 3 (18.8%), and subtotal resection in 1 (6.2%). Eight (88.9%) of the 9 patients with preoperative proptosis showed improvement after surgery, and 4 (66.7%) of the 6 patients with visual symptoms demonstrated improvement. Four (40%) of the 10 patients treated with ETOA experienced partial third nerve palsy immediately after surgery (3 transient and 1 persistent). There have been no postoperative CSF leaks or infections in this series.

CONCLUSIONS

Without transcranial approaches requiring temporalis muscle dissection and orbitozygomatic osteotomy, the selection of ETOA or EEA based on a concept of a four-zone model with its epicenter around the optic nerve successfully provides a minimally invasive 360° circumferential access to the entire orbit with acceptable morbidity.