Avoiding a Collision in Gamma Knife Radiosurgery : A Modified Mask Fixation Method

Objective@#: The latest version of the Leksell Gamma Knife IconTM allows for mask- and frame-based fixation. Although mask fixation provides fractionated treatment and immobilization using a noninvasive method, it is not free from collision. The authors investigated the collision problem with a modified mask fixation method. @*Methods@#: This study presents a case of two meningiomas in the frontal area, where a collision occurs in the occipital area. A modified mask fixation method was introduced to avoid the collision : first, the edges of the head cushion were cut off and polystyrene beads with a diameter of approximately 5 cm were removed. Next, the head cushion was sealed using a stapler. Finally, the head cushion was flattened in the adapter. We compared the shot coordinates, 3-dimensional (3D) error, clearance distance, and vertical depth of the head cushion between the initial and modified mask fixations. @*Results@#: When comparing the initial and modified mask fixations, the difference in the shot coordinates was +10.5 mm along the y-axis, the difference in the 3D error was approximately 18 mm, and the difference in clearance was -10.2 mm. The head cushion was approximately 8 mm deeper in the modified mask fixation. @*Conclusion@#: Based on these findings, we recommend a modified mask fixation method for gamma knife radiosurgery using ICON with a collision.

The Korean Society for Neuro-Oncology (KSNO) Guideline for the Management of Brain Tumor Patients During the Crisis Period: A Consensus Recommendation Using the Delphi Method (Version 2023.1)

Background@#During the coronavirus disease 2019 (COVID-19) pandemic, the need for appropriate treatment guidelines for patients with brain tumors was indispensable due to the lack and limitations of medical resources. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, has undertaken efforts to develop a guideline that is tailored to the domestic situation and that can be used in similar crisis situations in the future. @*Methods@#The KSNO Guideline Working Group was composed of 22 multidisciplinary experts on neuro-oncology in Korea. In order to reach consensus among the experts, the Delphi method was used to build up the final recommendations. @*Results@#All participating experts completed the series of surveys, and the results of final survey were used to draft the current consensus recommendations. Priority levels of surgery and radiotherapy during crises were proposed using appropriate time window-based criteria for management outcome. The highest priority for surgery is assigned to patients who are life-threatening or have a risk of significant impact on a patient’s prognosis unless immediate intervention is given within 24–48 hours. As for the radiotherapy, patients who are at risk of compromising their overall survival or neurological status within 4–6 weeks are assigned to the highest priority. Curative-intent chemotherapy has the highest priority, followed by neoadjuvant/adjuvant and palliative chemotherapy during a crisis period. Telemedicine should be actively considered as a management tool for brain tumor patients during the mass infection crises such as the COVID-19 pandemic. @*Conclusion@#It is crucial that adequate medical care for patients with brain tumors is maintained and provided, even during times of crisis. This guideline will serve as a valuable resource, assisting in the delivery of treatment to brain tumor patients in the event of any future crisis.

The Korean Society for Neuro-Oncology (KSNO) Guideline for the Management of Brain Tumor Patients During the Crisis Period: A Consensus Survey About Specific Clinical Scenarios (Version 2023.1)

Background@#During the coronavirus disease 2019 (COVID-19) pandemic, there was a shortage of medical resources and the need for proper treatment guidelines for brain tumor patients became more pressing. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, has undertaken efforts to develop a guideline that is tailored to the domestic situation and that can be used in similar crisis situations in the future. As part II of the guideline, this consensus survey is to suggest management options in specific clinical scenarios during the crisis period. @*Methods@#The KSNO Guideline Working Group consisted of 22 multidisciplinary experts on neuro-oncology in Korea. In order to confirm a consensus reached by the experts, opinions on 5 specific clinical scenarios about the management of brain tumor patients during the crisis period were devised and asked. To build-up the consensus process, Delphi method was employed. @*Results@#The summary of the final consensus from each scenario are as follows. For patients with newly diagnosed astrocytoma with isocitrate dehydrogenase (IDH)-mutant and oligodendroglioma with IDH-mutant/1p19q codeleted, observation was preferred for patients with low-risk, World Health Organization (WHO) grade 2, and Karnofsky Performance Scale (KPS) ≥60, while adjuvant radiotherapy alone was preferred for patients with high-risk, WHO grade 2, and KPS ≥60. For newly diagnosed patients with glioblastoma, the most preferred adjuvant treatment strategy after surgery was radiotherapy plus temozolomide except for patients aged ≥70 years with KPS of 60 and unmethylated MGMT promoters. In patients with symptomatic brain metastasis, the preferred treatment differed according to the number of brain metastasis and performance status. For patients with newly diagnosed atypical meningioma, adjuvant radiation was deferred in patients with older age, poor performance status, complete resection, or low mitotic count. @*Conclusion@#It is imperative that proper medical care for brain tumor patients be sustained and provided, even during the crisis period. The findings of this consensus survey will be a useful reference in determining appropriate treatment options for brain tumor patients in the specific clinical scenarios covered by the survey during the future crisis.

Multi-Layer Onlay Graft Using Hydroxyapatite Cement Placement without Cerebrospinal Fluid Diversion for Endoscopic Skull Base Reconstruction

Objective@#: The skull base reconstruction step, which prevents cerebrospinal fluid (CSF) leakage, is one of the most challenging steps in endoscopic skull base surgery (ESS). The purpose of this study was to assess the outcomes and complications of a reconstruction technique for immediate CSF leakage repair using multiple onlay grafts following ESS. @*Methods@#: A total of 230 consecutive patients who underwent skull base reconstruction using multiple onlay grafts with fibrin sealant patch (FSP), hydroxyapatite cement (HAC), and pedicled nasoseptal flap (PNF) for high-flow CSF leakage following ESS at three institutions were enrolled. We retrospectively reviewed the medical and radiological records to analyze the preoperative features and postoperative results. @*Results@#: The diagnoses included craniopharyngioma (46.8%), meningioma (34.0%), pituitary adenoma (5.3%), chordoma (1.6%), Rathke’s cleft cyst (1.1%) and others (n=21, 11.2%). The trans-planum/tuberculum approach (94.3%) was the most commonly adapted surgical method, followed by the trans-sellar and transclival approaches. The third ventricle was opened in 78 patients (41.5%). Lumbar CSF drainage was not performed postoperatively in any of the patients. Postoperative CSF leakage occurred in four patients (1.7%) due to technical mistakes and were repaired with the same technique. However, postoperative meningitis occurred in 13.5% (n=31) of the patients, but no microorganisms were identified. The median latency to the diagnosis of meningitis was 8 days (range, 2–38). CSF leakage was the unique risk factor for postoperative meningitis (p<0.001). @*Conclusion@#: The use of multiple onlay grafts with FSP, HAC, and PNF is a reliable reconstruction technique that provides immediate and complete CSF leakage repair and mucosal grafting on the skull base without the need to harvest autologous tissue or perform postoperative CSF diversion. However, postoperative meningitis should be monitored carefully.

The Korean Society for Neuro-Oncology (KSNO) Guideline for Adult Diffuse Midline Glioma: Version 2021.1

Background@#There have been no guidelines for the management of adult patients with diffuse midline glioma (DMG), H3K27M-mutant in Korea since the 2016 revised WHO classification newly defined this disease entity. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, had begun preparing guidelines for DMG since 2019. @*Methods@#The Working Group was composed of 27 multidisciplinary medical experts in Korea.References were identified through searches of PubMed, MEDLINE, EMBASE, and Cochrane CENTRAL using specific and sensitive keywords as well as combinations of keywords. As ‘diffuse midline glioma’ was recently defined, and there was no international guideline, trials and guidelines of ‘diffuse intrinsic pontine glioma’ or ‘brain stem glioma’ were thoroughly reviewed first. @*Results@#The core contents are as follows. The DMG can be diagnosed when all of the following three criteria are satisfied: the presence of the H3K27M mutation, midline location, and infiltrating feature. Without identification of H3K27M mutation by diagnostic biopsy, DMG cannot be diagnosed. For the primary treatment, maximal safe resection should be considered for tumors when feasible. Radiotherapy is the primary option for tumors in case the total resection is not possible. A total dose of 54 Gy to 60 Gy with conventional fractionation prescribed at 1-2 cm plus gross tumor volume is recommended. Although no chemotherapy has proven to be effective in DMG, concurrent chemoradiotherapy (± maintenance chemotherapy) with temozolomide following WHO grade IV glioblastoma’s protocol is recommended. @*Conclusion@#The detection of H3K27M mutation is the most important diagnostic criteria for DMG. Combination of surgery (if amenable to surgery), radiotherapy, and chemotherapy based on comprehensive multidisciplinary discussion can be considered as the treatment options for DMG.

The Korean Society for Neuro-Oncology (KSNO) Guideline for Antiepileptic Drug Usage of Brain Tumor: Version 2021.1

Background@#To date, there has been no practical guidelines for the prescription of antiepileptic drugs (AEDs) in brain tumor patients in Korea. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, had begun preparing guidelines for AED usage in brain tumors since 2019. @*Methods@#The Working Group was composed of 27 multidisciplinary medical experts in Korea.References were identified through searches of PubMed, MEDLINE, EMBASE, and Cochrane CENTRAL using specific and sensitive keywords as well as combinations of the keywords. @*Results@#The core contents are as follows. Prophylactic AED administration is not recommended in newly diagnosed brain tumor patients without previous seizure history. When AEDs are administered during peri/postoperative period, it may be tapered off according to the following recommendations. In seizure-naïve patients with no postoperative seizure, it is recommended to stop or reduce AED 1 week after surgery. In seizure-naïve patients with one early postoperative seizure (<1 week after surgery), it is advisable to maintain AED for at least 3 months before tapering. In seizure-naïve patients with ≥2 postoperative seizures or in patients with preoperative seizure history, it is recommended to maintain AEDs for more than 1 year. The possibility of drug interactions should be considered when selecting AEDs in brain tumor patients. Driving can be allowed in brain tumor patients when proven to be seizure-free for more than 1 year. @*Conclusion@#The KSNO suggests prescribing AEDs in patients with brain tumor based on the current guideline. This guideline will contribute to spreading evidence-based prescription of AEDs in brain tumor patients in Korea.

Multi-Layer Onlay Graft Using Hydroxyapatite Cement Placement without Cerebrospinal Fluid Diversion for Endoscopic Skull Base Reconstruction

Objective@#: The skull base reconstruction step, which prevents cerebrospinal fluid (CSF) leakage, is one of the most challenging steps in endoscopic skull base surgery (ESS). The purpose of this study was to assess the outcomes and complications of a reconstruction technique for immediate CSF leakage repair using multiple onlay grafts following ESS. @*Methods@#: A total of 230 consecutive patients who underwent skull base reconstruction using multiple onlay grafts with fibrin sealant patch (FSP), hydroxyapatite cement (HAC), and pedicled nasoseptal flap (PNF) for high-flow CSF leakage following ESS at three institutions were enrolled. We retrospectively reviewed the medical and radiological records to analyze the preoperative features and postoperative results. @*Results@#: The diagnoses included craniopharyngioma (46.8%), meningioma (34.0%), pituitary adenoma (5.3%), chordoma (1.6%), Rathke’s cleft cyst (1.1%) and others (n=21, 11.2%). The trans-planum/tuberculum approach (94.3%) was the most commonly adapted surgical method, followed by the trans-sellar and transclival approaches. The third ventricle was opened in 78 patients (41.5%). Lumbar CSF drainage was not performed postoperatively in any of the patients. Postoperative CSF leakage occurred in four patients (1.7%) due to technical mistakes and were repaired with the same technique. However, postoperative meningitis occurred in 13.5% (n=31) of the patients, but no microorganisms were identified. The median latency to the diagnosis of meningitis was 8 days (range, 2–38). CSF leakage was the unique risk factor for postoperative meningitis (p<0.001). @*Conclusion@#: The use of multiple onlay grafts with FSP, HAC, and PNF is a reliable reconstruction technique that provides immediate and complete CSF leakage repair and mucosal grafting on the skull base without the need to harvest autologous tissue or perform postoperative CSF diversion. However, postoperative meningitis should be monitored carefully.

The Korean Society for Neuro-Oncology (KSNO) Guideline for Adult Diffuse Midline Glioma: Version 2021.1

Background@#There have been no guidelines for the management of adult patients with diffuse midline glioma (DMG), H3K27M-mutant in Korea since the 2016 revised WHO classification newly defined this disease entity. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, had begun preparing guidelines for DMG since 2019. @*Methods@#The Working Group was composed of 27 multidisciplinary medical experts in Korea.References were identified through searches of PubMed, MEDLINE, EMBASE, and Cochrane CENTRAL using specific and sensitive keywords as well as combinations of keywords. As ‘diffuse midline glioma’ was recently defined, and there was no international guideline, trials and guidelines of ‘diffuse intrinsic pontine glioma’ or ‘brain stem glioma’ were thoroughly reviewed first. @*Results@#The core contents are as follows. The DMG can be diagnosed when all of the following three criteria are satisfied: the presence of the H3K27M mutation, midline location, and infiltrating feature. Without identification of H3K27M mutation by diagnostic biopsy, DMG cannot be diagnosed. For the primary treatment, maximal safe resection should be considered for tumors when feasible. Radiotherapy is the primary option for tumors in case the total resection is not possible. A total dose of 54 Gy to 60 Gy with conventional fractionation prescribed at 1-2 cm plus gross tumor volume is recommended. Although no chemotherapy has proven to be effective in DMG, concurrent chemoradiotherapy (± maintenance chemotherapy) with temozolomide following WHO grade IV glioblastoma’s protocol is recommended. @*Conclusion@#The detection of H3K27M mutation is the most important diagnostic criteria for DMG. Combination of surgery (if amenable to surgery), radiotherapy, and chemotherapy based on comprehensive multidisciplinary discussion can be considered as the treatment options for DMG.

The Korean Society for Neuro-Oncology (KSNO) Guideline for Antiepileptic Drug Usage of Brain Tumor: Version 2021.1

Background@#To date, there has been no practical guidelines for the prescription of antiepileptic drugs (AEDs) in brain tumor patients in Korea. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, had begun preparing guidelines for AED usage in brain tumors since 2019. @*Methods@#The Working Group was composed of 27 multidisciplinary medical experts in Korea.References were identified through searches of PubMed, MEDLINE, EMBASE, and Cochrane CENTRAL using specific and sensitive keywords as well as combinations of the keywords. @*Results@#The core contents are as follows. Prophylactic AED administration is not recommended in newly diagnosed brain tumor patients without previous seizure history. When AEDs are administered during peri/postoperative period, it may be tapered off according to the following recommendations. In seizure-naïve patients with no postoperative seizure, it is recommended to stop or reduce AED 1 week after surgery. In seizure-naïve patients with one early postoperative seizure (<1 week after surgery), it is advisable to maintain AED for at least 3 months before tapering. In seizure-naïve patients with ≥2 postoperative seizures or in patients with preoperative seizure history, it is recommended to maintain AEDs for more than 1 year. The possibility of drug interactions should be considered when selecting AEDs in brain tumor patients. Driving can be allowed in brain tumor patients when proven to be seizure-free for more than 1 year. @*Conclusion@#The KSNO suggests prescribing AEDs in patients with brain tumor based on the current guideline. This guideline will contribute to spreading evidence-based prescription of AEDs in brain tumor patients in Korea.

A National Consensus Survey for Current Practicein Brain Tumor Management I: Antiepileptic Drug andSteroid Usage

Background@#: The Guideline Working Group of the Korean Society for Neuro-Oncology (KSNO)conducted a nationwide questionnaire survey for diverse queries faced in the treatment of brain tumors.As part I of the survey, the aim of this study is to evaluate national patterns of clinical practiceabout antiepileptic drug (AED) and steroid usage for management of brain tumors. @*Methods@#: A web-based survey was sent to all members of the KSNO by email. The survey included9 questions of AED usage and 5 questions of steroid usage for brain tumor patients. All questionswere developed by consensus of the Guideline Working Group. @*Results@#: The overall response rate was 12.8% (54/423). Regarding AED usage, the majority ofrespondents (95.2%) routinely prescribed prophylactic AEDs for patients with seizure at the peri/postoperativeperiod. However, as many as 72.8% of respondents prescribed AED routinely for seizure-naïvepatients, and others prescribed AED as the case may be. The duration of AED prophylaxis showedwide variance according to the epilepsy status and the location of tumor. Levetiracetam (82.9%) wasthe most preferred AED for epilepsy prophylaxis. Regarding steroid usage, 90.5% of respondents usesteroids in perioperative period, including 34.2% of them as a routine manner. Presence of peritumoraledema (90.9%) was considered as the most important factor determining steroid usage followed bydegree of clinical symptoms (60.6%). More than half of respondents (51.2%) replied to discontinue thesteroids within a week after surgery if there are no specific medical conditions, while 7.3% preferredslow tapering up to a month after surgery. @*Conclusion@#: The survey demonstrated the prevailing practice patterns on AED and steroid usagein neuro-oncologic field among members of the KSNO. This information provides a point of referencefor establishing a practical guideline in the management of brain tumor patients.

A National Consensus Survey for Current Practicein Brain Tumor Management II:Diffuse Midline Glioma and Meningioma

Background@#: The Guideline Working Group of the Korean Society for Neuro-Oncology (KSNO)conducted a nationwide questionnaire survey for diverse queries faced in the treatment of brain tumors.As part II of the survey, the aim of this study is to evaluate the national patterns of clinical practicefor patients with diffuse midline glioma and meningioma. @*Methods@#: A web-based survey was sent to all members of the KSNO by email. The survey included4 questions of diffuse midline glioma and 6 questions of meningioma (including 2 case scenarios).All questions were developed by consensus of the Guideline Working Group. @*Results@#: In the survey about diffuse midline glioma, 76% respondents performed histologicconfirmation to identify H3K27M mutation on immunohistochemical staining or sequencing methods.For treatment of diffuse midline glioma, respondents preferred concurrent chemoradiotherapy withtemozolomide (TMZ) and adjuvant TMZ (63.8%) than radiotherapy alone (34.0%). In the surveyabout meningioma, respondents prefer wait-and-see policy for the asymptomatic small meningiomawithout peritumoral edema. However, a greater number of respondents had chosen surgical resectionas the first choice for all large size meningiomas without exception, and small size meningiomaswith either peritumoral edema or eloquent location. There was no single opinion with major consensuson long-term follow-up plans for asymptomatic meningioma with observation policy. As many as68.1% of respondents answered that they would not add any adjuvant therapies for World Health Organizationgrade II meningiomas if the tumor was totally resected including dura. @*Conclusion@#: The survey demonstrates the prevailing clinical practice patterns for patients with diffusemidline glioma and meningioma among members of the KSNO. This information provides a pointof reference for establishing a practical guideline in the management of diffuse midline glioma andmeningioma.

A National Consensus Survey for Current Practicein Brain Tumor Management III: Brain Metastasis andPrimary Central Nervous System Lymphoma

Background@#: The Guideline Working Group of the Korean Society for Neuro-Oncology (KSNO)conducted the nationwide questionnaire survey for diverse queries facing to treat patients with braintumor. As part III of the survey, the aim of this study is to evaluate the national patterns of clinical practicefor patients with brain metastasis and primary central nervous system lymphoma (PCNSL). @*Methods@#: A web-based survey was sent to all members of the KSNO by email. The survey included7 questions of brain metastasis and 5 questions of PCNSL, focused on the management strategiesin specific situations. All questions were developed by consensus of the Guideline WorkingGroup. @*Results@#" In the survey about brain metastasis, respondents preferred surgical resection withadjuvant treatment for patients with a surgically accessible single brain metastatic lesion less than 3cm in size without extracranial systemic lesions. However, most respondents considered radiosurgeryfor surgically inaccessible lesions. As the preferred treatment of multiple brain metastases according tothe number of brain lesions, respondents tended to choose radiotherapy with increasing number of lesions.Radiosurgery was mostly chosen for the brain metastases of less than or equal to 4. In the surveyabout PCNSL, a half of respondents choose high-dose methotrexate-based polychemotherapy asthe first-line induction therapy for PCNSL. The consolidation and salvage therapy showed a little variationamong respondents. For PCNSL patients with cerebrospinal fluid dissemination, intrathecal chemotherapywas most preferred. @*Conclusion@#: The survey demonstrates the prevailing clinical practice patterns for patients withbrain metastasis and PCNSL among members of the KSNO. This information provides a point of referencefor establishing a practical guideline in the management of brain metastasis and PCNSL.

An Updated Nationwide Epidemiology of Primary Brain Tumors in Republic of Korea, 2013

BACKGROUND: This report aims to provide accurate nationwide epidemiologic data on primary brain and central nervous system (CNS) tumors in the Republic of Korea. We updated the data by analyzing primary brain and CNS tumors diagnosed in 2013 using the data from the national cancer incidence database. METHODS: Data on primary brain and CNS tumors diagnosed in 2013 were collected from the Korean Central Cancer Registry. Crude and age-standardized rates were calculated in terms of gender, age, and histological type. RESULTS: A total of 11,827 patients were diagnosed with primary brain and CNS tumors in 2013. Brain and CNS tumors occurred in females more often than in males (female:male, 1.70:1). The most common tumor was meningioma (37.3%). Pituitary tumors (18.0%), gliomas (12.7%), and nerve sheath tumors (12.3%) followed in incidence. Glioblastomas accounted for 41.8% of all gliomas. In children (<19 years), sellar region tumors (pituitary and craniopharyngioma), embryonal/primitive/medulloblastoma, and germ cell tumors were the most common tumors. CONCLUSION: This study should provide valuable information regarding the primary brain tumor epidemiology in Republic of Korea.

Underexpression of HOXA11 Is Associated with Treatment Resistance and Poor Prognosis in Glioblastoma / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Homeobox (HOX) genes are essential developmental regulators that should normally be in the silenced state in an adult brain. The aberrant expression of HOX genes has been associated with the prognosis of many cancer types, including glioblastoma (GBM). This study examined the identity and role of HOX genes affecting GBM prognosis and treatment resistance. MATERIALS AND METHODS: The full series of HOX genes of five pairs of initial and recurrent human GBM samples were screened by microarray analysis to determine the most plausible candidate responsible for GBM prognosis. Another 20 newly diagnosed GBM samples were used for prognostic validation. In vitro experiments were performed to confirm the role of HOX in treatment resistance. Mediators involved in HOX gene regulation were searched using differentially expressed gene analysis, gene set enrichment tests, and network analysis. RESULTS: The underexpression of HOXA11 was identified as a consistent signature for a poor prognosis among the HOX genes. The overall survival of the GBM patients indicated a significantly favorable prognosis in patients with high HOXA11 expression (31±15.3 months) compared to the prognoses in thosewith low HOXA11 expression (18±7.3 months, p=0.03). When HOXA11 was suppressed in the GBM cell lines, the anticancer effect of radiotherapy and/or temozolomide declined. In addition, five candidate mediators (TGFBR2, CRIM1, TXNIP, DPYSL2, and CRMP1) that may confer an oncologic effect after HOXA11 suppression were identified. CONCLUSION: The treatment resistance induced by the underexpression of HOXA11 can contribute to a poor prognosis in GBM. Further investigation will be needed to confirm the value of HOXA11 as a potential target for overcoming the treatment resistance by developing chemo- or radiosensitizers.

Sclerosing Meningioma : Radiological and Clinical Characteristics of 21 Cases

OBJECTIVE: A rare subtype of meningioma, sclerosing meningioma is not included in the current World Health Organization classification of meningiomas and is classified into the category of other morphological variation subtypes. Sclerosing meningioma is often misdiagnosed to other non-benign meningioma or malignant neoplasm, so it is important to diagnose sclerosing type correctly. We analyzed the radiological and clinical characteristics of a series of sclerosing meningiomas. METHODS: Twenty-one patients who underwent surgery in one institute with a histopathologically proven sclerosing meningioma were included from 2006 to 2014. Eighteen tumors were diagnosed as a pure sclerosing-type meningioma, and 3 as mixed type. Magnetic resonance image was taken for all patients including contrast enhancement image. Computed tomography (CT) scan was taken for 16 patients. One neuroradiologist and 1 neurosurgeon reviewed all images retrospectively. RESULTS: In the all 16 patients with preoperative CT images, higher attenuation was observed in the meningioma than in the brain parenchyma, and calcification was observed in 11 (69%). In 15 of the 21 patients (71%), a distinctive very low signal intensity appeared as a dark color in T2-weighted images. Nine of these 15 tumors (60%) exhibited heterogeneous enhancement, and 6 (40%) exhibited homogeneous enhancement that was unlike the homogeneous enhancing pattern shown by conventional meningiomas. Ten patients had a clear tumor margin without peritumoral edema. CONCLUSION: Although these peculiar radiological characteristics are not unique to sclerosing meningioma, we believe that they are distinctive features that may be helpful for distinguishing sclerosing meningioma from other subtypes.

Catastrophic Intramedullary Abscess Caused by a Missed Congenital Dermal Sinus

Congenital dermal sinus (CDS) is a type of occult spinal dysraphism characterized by a midline skin dimple. A 12-month-old girl presented with fever and ascending quadriparesis. She had a midline skin dimple in the upper sacral area that had been discovered in her neonatal period. Imaging studies revealed a holocord intramedullary abscess and CDS. Overlooking CDS or misdiagnosing it as benign sacrococcygeal dimple may lead to catastrophic infection and cause serious neurological deficits. Therefore, further imaging work-up or consultation with a pediatric neurosurgeon is recommended following discovery of any atypical-looking dimples in the midline.