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Ji Eun Choi, Ho Jun Seol and Yang-Sun Cho

Endodermal cyst is a rare developmental cyst of the CNS, such as a Rathke cleft and colloid cyst lined by columnar epithelium of presumed endodermal origin. Intracranial endodermal cysts are rare, and most are found in the posterior fossa. The authors report a case of petroclival endodermal cyst with extensive bone destruction. A 12-year-old boy presented with transient facial weakness and headache. Imaging revealed a 3 × 3 × 4–cm, partial rim, enhanced cystic lesion in the petroclival area that was isointense on T1-weighted imaging and hyperintense in T2-weighted imaging. The cyst wall was partially removed and the cyst was obliterated using a lateral approach. Histological examination revealed ciliated, simple-to-pseudostratified cuboidal epithelium with a basement membrane that was consistent with an endodermal cyst, with the rare finding of xanthogranulomatous changes.

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Ho Jun Seol, Chun Kee Chung and Hyun Jib Kim

Object. The anterior upper thoracic spine (T1–3) is difficult to access because most neurosurgeons are unfamiliar with the anatomy. This study was performed to evaluate the different surgical options by retrospectively analyzing data on operations performed for anterior upper thoracic compression at the authors' institution.

Methods. Eighteen patients underwent surgery between November 1993 and May 2001. There were eight men and 10 women; their mean age was 55 years (range 28–80 years). All patients presented with pain and/or neurological deficits. The causes of anterior compression were diverse, although metastatic spinal tumor was most common. The approach chosen was primarily dictated by the axial involvement of the lesion. Anterior approaches, mainly the transmanubrium approach, were performed in six and posterior approaches in 12. In all cases except one, in which only an iliac bone graft was placed, instrumentation was used. The mean follow-up period was 11.4 months (range 1–57 months). One postoperative death occurred. Postoperative follow-up imaging studies, especially plain radiography, demonstrated no instrumentation failure. Improvement was shown in eight patients, an aggravation of symptoms in one, and stable clinical status in eight.

Conclusions. Decompression may be achieved on the anterior side of the upper thoracic spine if the operative approach is scrupulously chosen; this choice involves consideration of the locations of the lesion, the nature of the primary disease, and the surgery-related risk.

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Ho Jun Seol, Kyu-Chang Wang, Seung-Ki Kim, Yong-Seung Hwang, Ki Joong Kim and Byung-Kyu Cho

Object

Patients with moyamoya disease complain of headache before surgery, after surgery, or in both periods. To clarify the pathophysiological features of these headaches which are one of the major symptoms in moyamoya disease after indirect bypass surgery, the authors reviewed data obtained in patients with moyamoya disease who underwent such surgery at their institute.

Methods

The authors surveyed 204 children with moyamoya disease younger than 17 years of age who underwent indirect bypass surgery consecutively between 1988 and 2000. If headache and associated symptoms disturbed their daily activity, required rest and/or medication, and occurred at least once a month, the headache was regarded as significant and the patient was included in the study. A postoperative headache was defined as the presence of significant headache 12 months after the operation or later. Preoperative headache was documented in 44 patients. Postoperative headache was observed in 63% (28 of 44) of the patients with preoperative headache and in 6.3% (10 of 160) of those without preoperative headache. Aggravation on postoperative magnetic resonance images or single-photon emission computerized tomography scans did not correlate with this symptom (p = 0.729 and 0.203, respectively). The clinical course had the following features: 1) a coexisting stage of headache and transient ischemic attack; 2) a second stage of headache only; and 3) a final stage of improvement or disappearance of headache.

Conclusions

The authors demonstrated that headaches can persist or develop after indirect bypass surgery despite successful prevention of cerebral ischemia. In addition to decreased cerebral blood flow, progressive recruitment and redistribution of blood flow should be considered as a cause of headaches in patients with moyamoya disease.

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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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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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Ho Jun Seol, Duk Chul Shin, Yoo Seok Kim, Eun Bo Shim, Seung-Ki Kim, Byung-Kyu Cho and Kyu-Chang Wang

Object

Bilateral intimal thickening of the distal internal carotid arteries (ICAs) and the development of many collateral vessels in the base of the brain characterize moyamoya disease (MMD). Although the etiology of and the reason why MMD is limited to the major intracranial vessels remain unclear, flow dynamics, such as shear stress, may be related to its smooth-muscle cell migration. Therefore, this study was performed to determine the local hemodynamic factor, which concerns the predominance of specific anatomical sites, such as the distal ICA in the early stage and the proximal posterior cerebral artery (PCA) in the advanced stage of MMD.

Methods

The authors simulated the hemodynamics in the circle of Willis using computational models of 2D geometries of the distal ICA and PCA. A finite-element commercial package, automatic dynamics incremental nonlinear analysis (ADINA), was used to simulate blood flow in these arteries.

Results

Numerical results demonstrated that shear stress was relatively low at the ICA region. The distribution of shear stress was related to the predisposing area of MMD.

Conclusions

Diminished shear stress may promote stenosis of the distal ICA, which is a major pathological region in MMD.

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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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Yong Hwy Kim, Chiman Jeon, Young-Bem Se, Sang Duk Hong, Ho Jun Seol, Jung-II Lee, Chul-Kee Park, Dong Gyu Kim, Hee-Won Jung, Doo Hee Han, Do-Hyun Nam and Doo-Sik Kong

OBJECTIVE

The endoscopic endonasal approach for treating primary skull base malignancies involving the clivus is a formidable task. The authors hypothesized that tumor involvement of nearby critical anatomical structures creates hurdles to endoscopic gross-total resection (GTR). The aim of this study was to retrospectively review the clinical outcomes of patients who underwent an endoscopic endonasal approach to treat primary malignancies involving the clivus and to analyze prognostic factors for GTR.

METHODS

Between January 2009 and November 2015, 42 patients underwent the endoscopic endonasal approach for resection of primary skull base malignancies involving the clivus at 2 independent institutions. Clinical data; tumor locations within the clivus; and anatomical involvement of the cavernous or paraclival internal carotid artery, cisternal trigeminal nerve, hypoglossal canal, and dura mater were investigated to assess the extent of resection. Possible prognostic factors affecting GTR were also analyzed.

RESULTS

Of the 42 patients, 37 were diagnosed with chordomas and 5 were diagnosed with chondrosarcomas. The mean (± SD) preoperative tumor volume was 25.2 ± 30.5 cm3 (range 0.8–166.7 cm3). GTR was achieved in 28 patients (66.7%) and subtotal resection in 14 patients (33.3%). All tumors were classified as upper (n = 17), middle (n = 17), or lower (n = 8) clival tumors based on clival involvement, and as central (24 [57.1%]) or paramedian (18 [42.9%]) based on laterality of the tumor. Univariate analysis identified the tumor laterality (OR 6.25, 95% CI 1.51–25.86; p = 0.011) as significantly predictive of GTR. In addition, the laterality of the tumor was found to be a statistically significant predictor in multivariate analysis (OR 41.16, 95% CI 1.12–1512.65; p = 0.043).

CONCLUSIONS

An endoscopic endonasal approach can provide favorable clinical and surgical outcomes. However, the tumor laterality should be considered as a potential obstacle to total removal.

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Doo-Sik Kong, Stephanie Ming Young, Chang-Ki Hong, Yoon-Duck Kim, Sang Duk Hong, Jung Won Choi, Ho Jun Seol, Jung-Il Lee, Hyung Jin Shin, Do-Hyun Nam and Kyung In Woo

OBJECTIVE

Cranioorbital tumors are complex lesions that involve the deep orbit, floor of the frontal bone, and lesser and greater wing of the sphenoid bone. The purpose of this study was to describe the clinical and ophthalmological outcomes with an endoscopic transorbital approach (TOA) in the management of cranioorbital tumors involving the deep orbit and intracranial compartment.

METHODS

The authors performed endoscopic TOAs via the superior eyelid crease incision in 18 patients (16 TOA alone and 2 TOA combined with a simultaneous endonasal endoscopic resection) with cranioorbital tumors from September 2016 to November 2017. There were 12 patients with sphenoorbital meningiomas. Other lesions included osteosarcoma, plasmacytoma, sebaceous gland carcinoma, intraconal schwannoma, cystic teratoma, and fibrous dysplasia. Ten patients had primary lesions and 8 patients had recurrent tumors. Thirteen patients had intradural lesions, while 5 had only extradural lesions.

RESULTS

Of 18 patients, 7 patients underwent gross-total resection of the tumor and 7 patients underwent planned near-total resection of the tumor, leaving the cavernous sinus lesion. Subtotal resection was performed in 4 patients with recurrent tumors. There was no postoperative CSF leak requiring reconstruction surgery. Fourteen of 18 patients (77.8%) had preoperative proptosis on the ipsilateral side, and all 14 patients had improvement in exophthalmos; the mean proptosis reduced from 5.7 ± 2.7 mm to 1.5 ± 1.4 mm. However, some residual proptosis was evident in 9 of the 14 (64%). Ten of 18 patients (55.6%) had preoperative optic neuropathy, and 6 of them (60.0%) had improvement; the median best-corrected visual acuity improved from 20/100 to 20/40. Thirteen of 18 patients showed mild ptosis at an immediate postoperative examination, all of whom had a spontaneous and complete recovery of their ptosis during the follow-up period. Three of 7 patients showed improvement in extraocular motility after surgery.

CONCLUSIONS

Endoscopic TOA can be considered as an option in the management of cranioorbital tumors involving complex anatomical areas, with acceptable sequelae and morbidity.

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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.