Comparison of the Transcranial Approach and Transsphenoidal Approach Based on the Anatomical Location of Origin in Pediatric Craniopharyngiomas.

BACKGROUND: Various clinical classifications of craniopharyngiomas (CRPs) have been proposed to suggest optimal surgical planning. We aimed to evaluate the clinical outcomes of pediatric CRPs and the clinical significance of anatomical classification in relation to the diaphragm sellae. METHODS: A retrospective review was conducted on patients below 18 years of age who underwent surgery for CRPs from July 1998 to August 2022. The patients were divided into transcranial approach (TCA), and transsphenoidal approach (TSA) groups, which included microscopic TSA and endoscopic endonasal approach (EEA) groups. EEA has been adopted at our institute since 2011. CRPs were classified by their origin and relationship with the diaphragm sellae. RESULTS: A total of 132 pediatric CRP patients were included in this study, 117 of whom underwent surgery for primary CRP and 15 for recurrent CRP. Among them, 89 (67.4%) underwent TCA, 9 (6.8%) had microscopic TSA, and 34 (25.8%) had EEA. In subdiaphragmatic CRPs with competent diaphragm sellae, TSA tended to yield better outcomes than TCA did in terms of stalk preservation and ophthalmologic outcomes. After the introduction of EEA, the proportion of supradiaphragmatic CRPs treated via the TSA increased from 0% to 50% (P<0.001). Gross total resection (HR=0.194; 95% CI=0.102-0.367, P<0.001) and adjuvant therapy (HR=0.208; 95% CI=0.048-0.897, P=0.035) were found to be positive prognostic factors for long-term tumor control. CONCLUSIONS: Over time, with the adoption of EEA at our institute, the impact of anatomical classification on the surgical approach has decreased. Nevertheless, an individualized surgical approach should be employed to improve long-term outcomes and minimize complications for pediatric CRPs.

The role of surgery for optic pathway gliomas in the era of precision medicine.

Optic pathway gliomas (OPGs) represent a unique subset of brain tumours that primarily affect the paediatric population. Traditionally, these tumours are managed conservatively due to their location to and association with vital structures. This article explores the evolving role of surgery in the management of OPGs, particularly in the context of advancements in precision medicine. The advent of targeted therapy, especially for tumours with specific genetic alterations, such as BRAF V600E mutations, has revolutionized the treatment landscape, offering new avenues for patient-specific therapy. However, surgery still plays a crucial role, especially for debulking in cases of hydrocephalus or when standard therapies are ineffective. Advances in surgical techniques, including neuronavigation, endoscopic approaches, and intraoperative neurophysiological monitoring, have enhanced the safety and efficacy of operative interventions. Despite these developments, the complexity of OPGs necessitates a multidisciplinary approach, focusing on long-term outcomes and quality of life. Future research is needed to further elucidate the role of surgery in an era increasingly dominated by molecular genetics and targeted therapies.

Neurocognitive outcomes and associated clinical factors 5 years after surgery in children with craniosynostosis.

OBJECTIVE: Craniosynostosis involves early closure of one or more sutures, which is known to limit normal cranium growth and interfere with normal brain development. Various surgical methods are used, ranging from minimally invasive strip craniectomy to more extensive whole-vault cranioplasty. This study aimed to evaluate neurocognitive outcomes 5 years after surgical treatment in children with craniosynostosis and to evaluate relevant clinical factors. METHODS: After exclusion of genetically confirmed syndromic craniosynostosis patients, a retrospective review was conducted on 112 nonsyndromic craniosynostosis patients who underwent surgical treatment and follow-up neurocognitive assessment. Ninety-seven patients underwent strip craniectomy with postoperative orthotic helmet therapy, and 15 received other surgical treatment: 4 with distraction osteotomy and 11 with craniofacial reconstruction. Neurocognitive assessment using the Korean Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition (K-WPPSI-IV), was performed 5 years postoperatively. Clinical factors were assessed regarding neurocognitive outcomes. RESULTS: The mean age at surgery was significantly younger in the strip craniectomy group (strip craniectomy 4.6 months vs other surgical treatment 18.6 months, p < 0.01). Patients with 2 or more sutures involved were more likely to receive more extensive surgical treatment (16.5% in the strip craniectomy group vs 53.8% in the other group, p < 0.01). Four (3.5%) patients who showed evidence of increased intracranial pressure (ICP) also underwent more extensive surgical treatment. Multivariable linear regression revealed a significant correlation of age at neurocognitive testing (-3.18, 95% CI -5.95 to -0.40, p = 0.02), increased ICP (-34.73, 95% CI -51.04 to -18.41, p < 0.01), and the level of maternal education (6.11, 95% CI 1.01-11.20, p = 0.02) with the Full-Scale Intelligence Quotient (FSIQ). Age at surgery, involvement of 2 or more sutures, and type of operation demonstrated no correlation with FSIQ. Among the 97 patients who underwent strip craniectomy, the FSIQ ranged from mean ± SD 100.2 ± 10.2 (bicoronal) to 110.1 ± 12.7 (lambdoid), and there was no significant difference between the suture groups (p = 0.41). The 5 index scores were all within average ranges based on their age norms. CONCLUSIONS: Age at neurocognitive assessment, increased ICP, and maternal education level showed significant correlations with the neurocognitive function of craniosynostosis patients. Although children with craniosynostosis exhibited favorable 5-year postoperative neurocognitive outcomes across various synostosis sutures, longer follow-up is needed to reveal the incidence of neurocognitive dysfunction in these patients.

Measurement of the intersiphon distance for normal skull base development and estimation of the surgical window for the endoscopic transtuberculum approach in children.

OBJECTIVE: Due to the underdeveloped skull base in children, it is crucial to predict whether a sufficient surgical window for an endoscopic endonasal approach can be achieved. This study aimed to analyze the presumed surgical window through measurement of the intersiphon distance (ISD) and the planum-sella height (PSH) on the basis of age and its correlation with the actual surgical window for the endoscopic transtuberculum approach. METHODS: Twenty patients of each age from 3 to 18 years were included as the normal skull base population. ISD and PSH were measured and compared among consecutive ages. Additionally, 42 children with craniopharyngiomas or Rathke's cleft cysts who underwent treatment via the endoscopic transtuberculum approach were included. ISD and PSH were measured on preoperative images and then correlated with the dimensions of the surgical window on postoperative CT scans. The intraoperative endoscopic view was classified as narrow, intermediate, or wide based on operative photographs or videos, and relevant clinical factors were analyzed. RESULTS: In the normal skull base population, both ISD and the estimated area of the surgical window increased with age, particularly at 8 and 11 years old. On the other hand, PSH did not show an incremental pattern with age. Among the 42 children who underwent surgery, 24 had craniopharyngioma and 18 had Rathke's cleft cysts. ISD showed the strongest correlation with the actual area of the surgical window [r(40) = 0.69, p < 0.001] rather than with age or PSH. The visual grade of the intraoperative endoscopic view was narrow in 17 patients, intermediate in 21, and wide in 4. Preoperative ISD was 14.58 ± 1.29 mm in the narrow group, 16.13 ± 2.30 mm in the intermediate group, and 18.09 ± 3.43 mm in the wide group (p < 0.01). There were no differences in terms of extent of resection (p = 0.41); however, 2 patients in the narrow group had postoperative complications. CONCLUSIONS: Normal skull base development exhibited age-related growth. However, in children with suprasellar lesions, the measurement of the ISD showed a better correlation than age for predicting the surgical window for the endoscopic transtuberculum approach. Children with a small ISD should be approached with caution due to the limited surgical window.

Surgical treatment of interhemispheric arachnoid cysts.

OBJECTIVE: In children, interhemispheric arachnoid cysts (IHACs) are rare lesions often associated with corpus callosum dysgenesis. It is still controversial about surgical treatments for IHACs. We aim to report our experience with pediatric IHAC patients and evaluate surgical courses and neurological developments. METHODS: Pediatric IHACs treated between 2001 and 2021 were reviewed retrospectively. IHAC was observed until they represented rapid cyst enlargement or neurological symptoms. Cyst fenestration was done by microscope or endoscope, depending on the IHAC's location. Cyst size and corpus callosum dysgenesis were evaluated with neuroimaging. Neurological development was assessed from medical records at the last follow-up. RESULTS: Fifteen children received cyst fenestration surgery (mean age 11.4 months). Eleven patients (73.3%) under observation showed rapid cyst enlargement in a short period (median 5 months). Cysto-ventriculostomy (CVS) and cysto-cisternostomy (CCS) regressed the cyst size significantly (p = 0.003). The median follow-up duration was 51 months (range 14-178 months). Corpus callosum dysgenesis was observed in eleven patients (73.3%, complete = 5, partial = 6). Among eight patients (53.3%) having developmental delay, five patients (33.3%) showed speech delay, including one patient with intractable seizures. CONCLUSION: Pediatric IHACs frequently present within 1 year after birth, with rapid cyst enlargement. CVS and CCS were effective in regressing the cyst size. Corpus callosum dysgenesis accompanied by IHAC might have a risk of language achievement; however, development delay could rely on multifactorial features, such as epilepsy or other brain anomalies.

Choroid Plexus Hyperplasia : Report of Two Cases with Unique Radiologic Findings.

Choroid plexus hyperplasia (CPH), also known as diffuse villous hyperplasia of choroid plexus, is a rare condition characterized by excessive production of cerebrospinal fluid (CSF), resulting in hydrocephalus. Diagnosing CPH can be challenging due to the absence of clear imaging criteria for choroid plexus hypertrophy and the inability to assess CSF production non-invasively. As a result, many CPH patients are initially treated with a ventriculoperitoneal (VP) shunt, but subsequently require additional surgical intervention due to intractable ascites. In our study, we encountered two CPH patients who presented with significantly enlarged subarachnoid spaces, reduced parenchymal volume, and prominent choroid plexus. Initially, we treated these patients with a VP shunt, but eventually opted for endoscopic choroid plexus cauterization (CPC) to address the intractable ascites. Following the treatment with endoscopic CPC, we observed a gradual reduction in subarachnoid spaces and an increase in parenchymal volume. In cases where bilateral prominent choroid plexus, markedly enlarged subarachnoid spaces, and cortical atrophy are present, CPH should be suspected. In these cases, considering initial treatment with combined endoscopic CPC and shunt may help minimize the need for multiple surgical interventions.

Technical evolution of pediatric neurosurgery: moyamoya disease.

Moyamoya disease (MMD) is a rare steno-occlusive disease of the bilateral internal carotid arteries that predominantly occurs in East Asia. Since the first description of the MMD by Suzuki and Takaku in 1969, significant advances have been made in both basic and clinical understanding of the disease. The incidence and prevalence of pediatric MMD have increased, potentially due to improved detection rates. The advancement of neuroimaging techniques has enabled MRI-based diagnostics and detailed visualization of the vessel wall. Various methods of surgical treatments are successful in pediatric MMD patients, and recent studies emphasize the importance of reducing postoperative complications since the goal of MMD surgery is to prevent future cerebral infarction and hemorrhage. Long-term outcomes following appropriate surgical treatment in pediatric MMD patients have shown promising results, including favorable outcomes in very young patients. Further studies with a large patient cohort are needed to establish individualized risk group stratification for determining the optimal timing of surgical treatment and to conduct multidisciplinary outcome assessments.

Comparison of Bifrontal Craniotomy and Multiple Burr Hole Encephalogaleoperiosteal-Synangiosis for Pediatric Moyamoya Disease: An Experience of 346 Patients.

BACKGROUND AND OBJECTIVES: Moyamoya disease (MMD) is a steno-occlusive disease treated with revascularization surgery. Craniotomy and multiple burr hole encephalogaleoperiosteal-synangiosis (EGPS) are used for revascularization of the anterior cerebral artery territory. The aim of this study was to compare the clinical outcome between the 2 surgical methods in pediatric patients with MMD. METHODS: A retrospective review of patients with MMD who underwent bifrontal indirect bypass surgery was performed. Clinical features, perioperative data, and angiographic, perfusion, and functional outcomes were compared between the 2 groups. Propensity score matching was performed to compare the perioperative characteristics and clinical outcomes. RESULTS: A total of 346 patients were included in this study, 111 patients underwent bifrontal craniotomy EGPS, and 235 patients had bifrontal multiple burr hole EGPS. An insignificant higher rate of postoperative infarction (11.7% vs 5.5%, P = .072) and more postoperative hemorrhage occurred in the craniotomy EGPS group (3.6% vs 0%, P = .004). Of the 83 patients selected with propensity score matching for each group, the duration of operation was shorter ( P < .001) and the amount of intraoperative bleeding was significantly less in the multiple burr hole EGPS group ( P = .008). There was no difference in clinical outcomes between the 2 groups. CONCLUSION: Bifrontal multiple burr hole EGPS has benefits over craniotomy with shorter surgical time, less intraoperative bleeding, fewer postoperative complications, and comparable perfusion and functional outcomes. Multiple burr hole EGPS is a safe and effective method that might be considered for revascularization of the anterior cerebral artery territory in pediatric patients with MMD.

Comparison of the clinical features and treatment outcomes of pilocytic astrocytoma in pediatric and adult patients.

PURPOSE: Pilocytic astrocytoma is a slow-growing tumor that predominantly develops in children, but has a broad age spectrum. A notable characteristic of pilocytic astrocytoma is that the tumor arises in diverse locations and the clinical course is not always benign. Therefore, it is necessary to elucidate the clinical spectrum of the disease and analyze the relevant prognostic factors. METHODS: Demographic and treatment-related factors were retrospectively reviewed in a cohort of 254 patients with histologically confirmed pilocytic astrocytoma. Clinical features were compared between the pediatric group (N = 208; age < 18 years) and the adult group (N = 46; age ≥ 18 years). Cox regression analysis was performed to identify relevant prognostic factors. RESULTS: There was no difference in progression-free survival (PFS) between the pediatric and adult groups (p = 0.36); however, patients under 8 years of age exhibited worse PFS (p < 0.01). Leptomeningeal seeding at diagnosis and pilomyxoid histology was observed only in pediatric patients. In the pediatric group, nine patients experienced recurrence after complete resection. Increasing age (hazard ratio (HR) = 0.89, p < 0.01) and adjuvant therapy (HR = 0.32, p < 0.01) were protective factors against tumor progression. In the adult group, no progression occurred after complete resection. Age and adjuvant therapy were not significant factors in the adult group. CONCLUSION: Pilocytic astrocytoma presents with a diverse clinical spectrum. Complete resection is of utmost importance, and appropriate adjuvant treatment is recommended if complete resection cannot be achieved. Children with younger age are associated with more aggressive tumors, and recurrence may occur even after complete resection.

Electrodiagnosis has a potential to identify neural damage in asymptomatic infants with closed spinal dysraphism.

PURPOSE: The presence and progression of symptoms is the basis for deciding to perform surgery in infants with closed spinal dysraphism (CSD); however, identifying symptoms could be limited, making it difficult to decide. This study investigated whether an electrodiagnostic study (EDS) can provide evidence of neural damage in asymptomatic infants with CSD. METHODS: The study group comprised infants with CSD suspected of having neural damage based on structural abnormalities in spinal ultrasound findings. The patients' medical records were reviewed retrospectively for their clinical presentation, neuroimaging findings, urodynamic study (UDS) results, EDS findings, and surgical status. RESULTS: Among 125 infants who underwent EDS and UDS, 117 (94%) had no clinical symptoms, except for cutaneous manifestations. Among these asymptomatic patients, 51 individuals (43.6%) had abnormal EDS findings; 33 subjects (28.2%) showed abnormal findings on EDS alone, while 37 (31.6%) on UDS alone, and 18 (15.4%) on both EDS and UDS. Chi-square test showed an opposite relationship between the two test results; when EDS was abnormal, UDS was often normal and vice versa (χ2 = 5.328, p = 0.021). In all cases with abnormal EDS, denervation potentials, such as fibrillation and positive sharp waves, were observed on needle electromyography. However, abnormal findings in the nerve conduction study were observed only in six cases. CONCLUSION: Subclinical neural damage was identified through EDS in asymptomatic infants with CSD. EDS could be necessary to determine whether follow-up monitoring only or surgical intervention is required for this patient group complementing UDS findings.

Diverse Patterns and Clinical Significance of 11C-Methionine PET in Dysembryoplastic Neuroepithelial Tumors.

PURPOSE: Dysembryoplastic neuroepithelial tumors (DNETs) are slow-growing epilepsy-associated tumors. Low or normal 11C-methionine (MET) PET uptake helps to differentiate DNETs from other low-grade gliomas. However, diverse MET-PET uptake in DNETs has been observed. The aim of this study is to measure the clinical significance and prognostic value of MET-PET in DNET management. PATIENTS AND METHODS: Retrospective review of 26 DNET patients was done. Clinical characteristics, radiologic findings, and visual and quantitative MET-PET results were analyzed. PET uptake was calculated as the tumor-to-homotopic mirror ratio (TNRm) and tumor-to-contralateral cortex ratio (TNRc). The clinical activity of the tumors at the time of PET was classified into active and quiescent groups. The surgical outcome was defined as a composite of 2 different aspects: tumor progression and/or clinical events such as seizure recurrence or tumor bleeding. RESULTS: Twenty-seven MET-PET examinations (20 initial MET-PET and 7 MET-PET during follow-up) were included. Clinically active tumors at the time of PET presented significantly higher values of TNRm and TNRc than quiescent tumors. High MET-PET uptake by visual grading, TNRm ≥ 1.90, and TNRc ≥ 1.85 exhibited poor prognosis for event-free survival. CONCLUSIONS: MET-PET uptake correlates well with the clinical behavior of DNETs at the time of PET examination. Moreover, High MET-PET uptake is closely related to seizure recurrence if tumors are not entirely resected. Efforts to achieve gross total resection should be made for DNETs with high MET-PET uptake.

Molecular subgrouping of medulloblastoma in pediatric population using the NanoString assay and comparison with immunohistochemistry methods.

PURPOSE: Molecular subgrouping of medulloblastoma has become important due to its impact on risk group stratification. Immunohistochemistry (IHC) has been widely used but it has innate limitations. The NanoString assay has been proposed as an alternative method. This study aims to present the characteristics of medulloblastoma subgrouped by the NanoString assay and to compare the subgrouping results with the IHC method. METHODS: Pediatric patients with histological diagnosis of medulloblastoma who underwent surgery from 2007 to 2021 were included. Clinical characteristics, pathological findings were reviewed. Molecular subgrouping was performed by IHC and by NanoString nCounter Elements TagSets assay. Test for concordance between two methods was made. RESULTS: Among a total of 101 patients analyzed, subgrouping using the NanoString assay resulted in 14 (13.8%) WNT, 20 (19.8%) SHH, 18 (17.8%) Group 3, and 39 (38.6%) Group 4 subgroup cases. Survival analysis revealed the following from best to worse prognosis: WNT, Group 4, SHH, and Group 3. In SHH subgroup the large cell/anaplastic histology was present in 30% of cases. Seventy-one cases were analyzed for concordance between NanoString and IHC. Cohen's kappa value indicated moderate agreement but identification of Groups 3 and 4 with IHC using NPR3 and KCNA1 markers exhibited poor results. CONCLUSIONS: The NanoString assay of Korean medulloblastoma patients revealed a more aggressive clinical course in the SHH subgroup which may be explained by a higher proportion of large cell/anaplastic histology being present in this subgroup. IHC did not distinguish Group 3 or 4 accurately. The NanoString assay may represent a good alternative method for practical use in the clinical field.

Myelomeningocele as an anomaly of secondary neurulation.

PURPOSE: Myelomeningocele (MMC) is the representative entity of open neural tube defects resulting from an error during primary neurulation. However, cases of MMC in the region of the secondary neural tube (below the junction of S1 and S2 vertebrae) are sometimes encountered. We aimed to analyze the clinical features of atypical "low-lying" MMC in comparison to the typical MMC and suggest possible pathoembryogenesis. METHODS: From 1986 to 2020, 95 MMC patients were treated in our institute. A retrospective review of the radiological and clinical information was performed. We defined "low-lying" MMCs as those with fascia or lamina defects below the S1-2 interspinous ligament. RESULTS: Thirty-one out of the 95 MMC patients were identified as having low-lying MMC. The percentage of low-lying MMC within the entire MMC group increased dramatically (19% from 1990 to 1999 and 48% from 2000 to 2020). Thirty-nine percent of the low-lying MMCs were associated with hydrocephalus, and 36% showed the Chiari malformation. Clean intermittent catheterization was being performed by 52% of the patients and 46% had a motor weakness. The proportions of hydrocephalus, neurological symptoms, and the number of related procedures in the low-lying MMC were substantially lower than the typical MMC in our cohort and the literature. CONCLUSIONS: We present cases of atypical MMC occurring in the region of secondary neurulation. These cases provide clues that secondary neurulation may lead to open neural defects. Future experiments with animal models supporting what we have seen in the clinics will greatly enhance the understanding of the developmental process of neurulation and the corresponding anomalies.

Clinical Outcome of Optic Pathway and Hypothalamic Gliomas: A 20-Year Single-Institution Retrospective Study.

BACKGROUND: Optic pathway and hypothalamic gliomas (OPHGs) are challenging to surgically remove owing to their anatomical relationship. We previously reported on surgical treatment outcomes over a 10-year time frame. The purpose of this study was to update the OPHG clinical outcomes for cases in which chemotherapy has become the primary treatment option. The role of surgery was also revisited. METHODS: Patients with a diagnosis of OPHG who underwent treatment at Seoul National University Children's Hospital from February 1999 to July 2019 were included. A multidisciplinary approach was used to determine the patients' treatment plans. Chemotherapy was the first-line treatment for all patients. When symptoms of hydrocephalus existed, debulking surgery was performed to reopen the flow of cerebrospinal fluid. RESULTS: The study included 47 patients with OPHGs. The mean age was 6.9 years. Neurofibromatosis 1 was diagnosed in 3 patients. The extent of removal was none or biopsy in 13 (28%) cases, partial resection in 23 (49%) cases, and subtotal to gross total resection in 11 (23%) cases. In 32 (68%) patients, chemotherapy was first-line treatment. Ascites after ventriculoperitoneal shunt occurred in 3 cases, and 2 cases were successfully managed with debulking surgery. Treatment outcomes showed a 5-year overall survival rate of 97.7% and a 5-year progression-free survival rate of 47.7%. CONCLUSIONS: OPHG management using less invasive operations and chemotherapy as first-line treatment is feasible. Debulking surgery in patients with OPHGs may be considered in cases with cerebrospinal fluid pathway obstruction, progression despite chemotherapy or radiation, and refractory shunt-related ascites.

Comparative study between open and arthroscopic techniques for scaphoid excision and four-corner arthrodesis.

This study presents our technique of arthroscopic scaphoid excision and four-corner arthrodesis and compares the clinical and radiological outcomes with those achieved with the open method. Twenty-seven patients (14 in arthroscopy group and 13 in open group) were included. Bone union was achieved in 13 of 14 patients in the arthroscopy group and in all 13 patients in the open group. In the open group, severe stiffness (flexion-extension arc was 10°) occurred in one patient after surgery. The mean postoperative flexion-extension arc was 75° and 51° in the arthroscopy group and open group, respectively. The pain, clinical scores, and radiological indices were improved in both arthroscopy and open groups. Arthroscopic and open scaphoid excision and four-corner arthrodesis did not show significant differences in clinical outcomes and bone union rates. The arthroscopic method provided a superior range of motion.Level of evidence: III.

Limited Dorsal Myeloschisis: Reconsideration of its Embryological Origin.

BACKGROUND: Limited dorsal myeloschisis (LDM) is postulated to be a result of incomplete dysjunction in primary neurulation. However, clinical experience of LDM located below the first-second sacral (S1-S2) vertebral level, which is formed from secondary neurulation (S2-coccyx), suggested that LDM may not be entirely explained as an error of primary neurulation. OBJECTIVE: To elucidate the location and characteristics of LDM to investigate the possible relation of its pathoembryogenesis to secondary neurulation. METHODS: Twenty-eight patients were surgically treated for LDM from 2010 to 2015. Since the level where the LDM stalk penetrates the interspinous ligament is most clearly defined on the preoperative MRI and operative field, this level was assessed to find out whether the lesions can occur in the region of secondary neurulation. RESULTS: Eleven patients (39%) with typical morphology of the stalk had interspinous defect levels lower than S1-S2. These patients were not different from 17 patients with classic LDMs at a level above or at S1-S2. This result shows that other than the low level of the interspinous level, 11 patients had lesions that could be defined as LDMs. CONCLUSION: By elucidating the location of LDM lesions (in particular, the interspinous level), we propose that LDM may be caused by errors of secondary neurulation. The hypothesis seems more plausible due to the supportive fact that the process of separation between the cutaneous and neural ectoderm is present during secondary neurulation. Hence, incomplete disjunction of the two ectoderms during secondary neurulation may result in LDM, similar to the pathomechanism proposed during primary neurulation.

Fractionated Stereotactic Gamma Knife Radiosurgery for Large Brain Metastases: A Retrospective, Single Center Study.

PURPOSE: Stereotactic radiosurgery (SRS) is widely used for brain metastases but has been relatively contraindicated for large lesions (>3 cm). In the present study, we analyzed the efficacy and toxicity of hypofractionated Gamma Knife radiosurgery to treat metastatic brain tumors for which surgical resection were not considered as the primary treatment option. METHODS AND MATERIALS: Thirty-six patients, forty cases were treated with Gamma Knife-based fractionated SRS for three to four consecutive days with the same Leksell frame on their heads. The mean gross tumor volume was 18.3 cm³, and the median dose was 8 Gy at 50% isodose line with 3 fractions for three consecutive days (range, 5 to 11 Gy and 2 to 4 fractions for 2 to 4 consecutive days). Survival rates and prognostic factors were analyzed. RESULTS: The overall survival rate at one and two years was 66.7 and 33.1%, respectively. The median survival time was 16.2 months, and the local control rate was 90%. RTOG toxicity grade 1 was observed in 3 (8.3%) patients, grade 2 in 1 (2.7%) patient and grade 3 in 1 (2.7%) patient respectively. Radiation necrosis was developed in 1 (2.7%) patient. KPS scores and control of primary disease resulted in significant differences in survival. CONCLUSIONS: Our findings suggest that consecutive hypofractionated Gamma Knife SRS could be applied to large metastatic brain tumors with effective tumor control and low toxicity rates.

Brain Edema after Repeat Gamma Knife Radiosurgery for a Large Arteriovenous Malformation: A Case Report.

Brain edema due to venous thrombosis following stereotactic radiosurgery for a cerebral arteriovenous malformation (AVM) has rarely been reported. We report a patient with a large AVM in the eloquent area, and brain edema developed in this area after repeat Gamma knife stereotactic radiosurgery (GKRS). An 18-year-old female presented with a 4-year-history of persistent headache. Magnetic resonance imaging and transfemoral carotid angiogram revealed a high-flow large AVM in the left parieto-occipital area. Brain edema developed and aggravated patient's symptoms after time-staged GKRS. The cause of edema was thought to be the failure of the surrounding venous channels to drain the venous flow from the normal brain and the drainage was hampered by the persistent shunt flow from the AVM, which was due to the thrombosis of one huge draining vein of the AVM. The microsurgical resection of the AVM nidus eliminated shunt flow and completely normalized the brain edema. Microsurgical resection of the AVM nidus completely normalized the brain edema due to thrombosis of a draining vein of an AVM develops after SRS.