Primary germinoma of the medulla oblongata: illustrative case.

BACKGROUND: Primary central nervous system germinomas of the medulla oblongata are extremely rare and usually have been found in young female Asian patients. The authors present an illustrative case of a patient who presented with severe medullary and posterior cord syndrome, the first South American case published to date, to the authors' knowledge. OBSERVATIONS: Initially, the radiological differential diagnosis did not include this entity. The lesion was located at the obex and exhibited a well-delineated contrast enhancement without hydrocephalus. An emergency decompressive partial resection following functional limits was performed. After histological confirmation, radiotherapy was indicated, with complete remission achieved at a 6-month follow-up. The patient, however, continued to have a severe proprioceptive disorder. The literature review identified 21 other such patients. The mean age for this location was 23 years, with a strong female and Asian origin predilection. All tumors exhibited contrast enhancement, and only one presented with hydrocephalus. LESSONS: In the absence of elevated tumor markers, radiological clues such as a well-delineated, contrast-enhanced lesion arising from the obex, without hydrocephalus, associated with demographic features such as young age, female sex, and Asian heritage, should evoke a high level of suspicion for this diagnosis. Gross total resection must not be attempted, because this tumor is potentially curable with high-dose radiotherapy.

Morphological observations in brain arteriovenous malformations after gamma knife radiosurgery.

Morphological studies after Gamma Knife radiosurgery (GKRS) revealed endothelial destruction followed by spindle-shaped cell proliferation in the subendothelial region and in the connective tissue stroma of arteriovenous malformation (AVM) vessels. Histological, immunohistochemical and ultrastructural characteristics of this spindle-shaped cell population in the irradiated AVMs were reminiscent of those described as myofibroblasts in wound healing processes and pathological fibromatoses. These modified fibroblasts have contractile capacity, therefore this might contribute to the vessel occlusion, shrinking process and final volume reduction of AVMs after GKRS. Similar histopathological changes were observed in a cavernous malformation following high-dose irradiation.

Patterns of neurovascular compression in patients with classic trigeminal neuralgia: A high-resolution MRI-based study.

PURPOSE: To describe the anatomical characteristics and patterns of neurovascular compression in patients suffering classic trigeminal neuralgia (CTN), using high-resolution magnetic resonance imaging (MRI). MATERIALS AND METHODS: The analysis of the anatomy of the trigeminal nerve, brain stem and the vascular structures related to this nerve was made in 100 consecutive patients treated with a Gamma Knife radiosurgery for CTN between December 1999 and September 2004. MRI studies (T1, T1 enhanced and T2-SPIR) with axial, coronal and sagital simultaneous visualization were dynamically assessed using the software GammaPlan™. Three-dimensional reconstructions were also developed in some representative cases. RESULTS: In 93 patients (93%), there were one or several vascular structures in contact, either, with the trigeminal nerve, or close to its origin in the pons. The superior cerebellar artery was involved in 71 cases (76%). Other vessels identified were the antero-inferior cerebellar artery, the basilar artery, the vertebral artery, and some venous structures. Vascular compression was found anywhere along the trigeminal nerve. The mean distance between the nerve compression and the origin of the nerve in the brainstem was 3.76±2.9mm (range 0-9.8mm). In 39 patients (42%), the vascular compression was located proximally and in 42 (45%) the compression was located distally. Nerve dislocation or distortion by the vessel was observed in 30 cases (32%). CONCLUSIONS: The findings of this study are similar to those reported in surgical and autopsy series. This non-invasive MRI-based approach could be useful for diagnostic and therapeutic decisions in CTN, and it could help to understand its pathogenesis.

MR-based follow-up of the superior cerebellar artery after radiosurgery for trigeminal neuralgia.

PURPOSE: To study with a non invasive method any potential radiological change on the superior cerebellar artery (SCA) in patients treated radiosurgically for classic trigeminal neuralgia (CTN). MATERIALS AND METHODS: A retrospective measure of maximal dose received by SCA was performed analyzing the treatment planning in 55 consecutive patients treated by Gamma Knife radiosurgery for an CTN, then, a prospective study was designed using high resolution MR, with T2 SPIR, T1 without and with gadolinium enhancement, Proton density, 3D TONE and MIP reconstructions. Inclusion criteria were: patients followed at our institution, follow-up of one year or more, dose received by the SCA of 15 Gy or more and voluntary patient participation in the study. Patients with repeated Gamma Knife radiosurgery for failure or recurrence were excluded. The end points were: SCA occlusion, stenosis or infarction in the territory supplied by SCA. RESULTS: Sixteen patients were studied, with a mean follow-up of 25.2 months (12-42 months). The mean maximal dose received by the SCA was 57.5 Gy. (15-87 Gy). Among these 16 patients studied, neither obstruction of the SCA nor infarction was demonstrated. In one patient a suspicion of asymptomatic SCA stenosis was visualized distant to the irradiation field. CONCLUSIONS: SCA can receive a high dose of irradiation during radiosurgical treatment for CTN. This study does not confirm any vascular damage to the SCA after radiosurgery for CTN.

Resección de lesiones cerebrales con asistencia de mapeo cortical intraoperatorio / Intraoperative cortical mapping in surgery for brain lesions

Introducción: Se ha demostrado que la resección extensa de tumores intracraneanos intra-axiales malignos mejora la sobrevida. Esto no siempre es posible dada la eventual ubicación de estos tumores en o cercanos a áreas elocuentes, como corteza motora primaria o de lenguaje. En estas circunstancias, el desafío es evitar secuelas neurológicas. Uno de los métodos para disminuir dicho riesgo es el mapeo cortical intraoperatorio (MCI). El presente trabajo describe la técnica de mapeo cortical intraoperatorio de áreas elocuentes, al igual que su factibilidad y complementariedad con otras técnicas de localización tumoral. Método: Se analizan 7 pacientes operados, portadores de lesiones cercanas a áreas elocuentes. Se utilizó neuronavegación y MCI (estimulación directa de corteza y registro de potenciales evocados somatosensoriales). Se analizó la localización, tamaño y tipo de la lesión, grado de resección y estado neurológico pre y postoperatorio. Resultados: En todos los pacientes el MCI fue efectivo en localizar corteza motora primaria. Hubo 6 pacientes en los que se pudo resecar el área tumoral no asociada a funcionalidad, logrando en 5 de ellos resección completa o superior al 90 por ciento. En un paciente la lesión correspondió a una malformación arteriovenosa profunda ubicada en corteza motora primaria en que el MCI permitió una vía de abordaje por corteza no elocuente para su resección completa. No hubo déficit neurológico agregado postoperatorio con seguimiento de 12 meses. Conclusión: El MCI es útil y localiza en forma efectiva, simple y reproducible áreas de corteza funcional, haciendo posible realizar resecciones extensas de tumores en áreas elocuentes. Esta técnica es complementaria a otros métodos de ubicación anatómica y fisiológica pudiendo contribuir a una cirugía más segura y efectiva.

Introduction: Extensive resection for malignant intraaxial intracranial tumors has been demonstrated to improve survival. This is not always possible due to potential tumor location in or next to eloquent brain regions, like primary motor cortex or speech areas. In this case, avoiding neurological deficits is challenging. One of the tools for minimizing that risk is intraoperative cortical mapping (ICM). This report describes the ICM technique of eloquent brain regions, feasibility and complementariness with other methods for tumor localization. Methods: Seven patients with brain lesions near eloquent regions operated on were analyzed. Frameless stereotaxis (neuronavigation) and intraoperative cortical mapping (direct cortical stimulation and monitoring of somatosensory evoked potentials) were used. The location, size, type of lesion, amount of resection, pre and postoperative neurological status were studied. Results: ICM was effective in localizing primary motor cortex in all patients. In 6 patients the tumor area without functionality was removed, achieving complete or greater than 90 percent resection in 5 of them. In one patient the lesion was a deep arteriovenous malformation located below the primary motor cortex. In this case ICM made feasible an approach from non-eloquent cortex to achieve total resection. No new postoperative deficit was found in a 12 month follow-up period. Conclusion: ICM is useful and localize functional cortical regions effectively, simply and reliably, making possible to perform extensive tumor resections in eloquent regions. This technique is complementary to other tools for anatomical or physiological localization and could contribute to a safer and more effective surgery.

Brain stem metastases treated with radiosurgery: prognostic factors of survival and life expectancy estimation.

BACKGROUND: The objective of this study is to study prognostic factors of survival and 3 stratification systems for life expectancy estimation in patients with brain stem metastases treated with radiosurgery. METHODS: Between December 1999 and November 2006, 25 patients with 27 brain stem metastases were treated with Gamma Knife radiosurgery. The lesions' mean volume was 0.6 mL (0.013-3.6 mL). The mean marginal dose was 20 Gy (15-24 Gy). Univariate and multivariate studies were done to identify prognostic factors, and 3 patient stratification systems were applied for survival estimation: RPA, SIR, and BSBM. RESULTS: The primary tumor location was in the lungs in 12 patients, breast in 8, and other in 5. Fourteen lesions were located in the pons, 9 in the midbrain, and 4 in the medulla. All patients were followed clinically. Radiologic follow-up was available in 21 lesions (78%). Tumor control was achieved in all but one followed lesion (95%). There were no complications related to treatment. Median survival of patients with brain stem metastases was 11.1 months. In multivariate analysis, KPS of 80 or more, control of the primary tumor, absence of radiotherapy, and a marginal dose higher than 18 Gy were associated with better survival. The BSBM in the univariate and multivariate analyses was the strongest predictor of survival (P < .0001). CONCLUSIONS: The BSBM was the most useful tool for estimating survival. Rather than the brain stem location of an intracranial metastasis, the patient integral clinical status seems to be more important in determining survival.

Diagnóstico y tratamiento de las metástasis encefálicas: [revisión] / Diagnosis and treatment of brain metastasis: [review]

Cerebral metastasis occur in 20 to 30 percent of patients with systemic cancer and are the most common type of intracranial tumor. The median survival of untreated patients is one month with a slightly longer survival in those treated with steroids. Patients treated with whole brain radiation therapy survive between 3 to 6 months. In selected cases survival can increase to 10 to 12 months with combination of surgery and radiotherapy or stereotactic radiosurgery alone or associated to radiotherapy. Most brain metástasis arise from lung, breast and melanomas. The most important criteria for selecting patients who will benefit from surgery or stereotactic radiosurgery are a Karnofsky score of 70 or more, systemic control of the cancer and absence of leptomeningeal involvement. Surgery is indicated in patients with a single lesion located in an accessible zone and stereotactic radiosurgery is indicated for lesions up to 3 cm of diameter, and in patients with up to 3 or 4 metastasis, no matter their location. The survival benefit of chemotherapy in brain metastasis has not been demonstrated.

Neurovascular compression anatomy and pain outcome in patients with classic trigeminal neuralgia treated by radiosurgery.

OBJECTIVE: To study the influence of the anatomy of neurovascular compression (NVC) on pain outcome in patients with classic trigeminal neuralgia treated by radiosurgery. METHODS: Analysis of the anatomy of the trigeminal nerve, brainstem, and vessels was performed in 89 consecutive patients treated by Leksell gamma knife (Elekta Instruments, Stockholm, Sweden) for classic trigeminal neuralgia. One-millimeter axial magnetic resonance imaging slices (T1-weighted, T1-weighted enhanced, and T2-weighted selected partial inversion recovery) with coronal, sagittal, and three-dimensional reconstructions were viewed. The end point for outcome was total pain remission and no medication. The follow-up period ranged between 6 and 42 months. RESULTS: In 82 patients (92%), a vascular structure in contact with the nerve was observed. In four patients, the NVC was produced by a large vessel (basilar or vertebral artery) and in 78 by a smaller vessel. The superior cerebellar artery was the cause of the NVC in 64 patients (78%). The NVC was proximal (<3 mm to the brainstem) in 34 patients (41%) and distal in 43 patients (52%). Nerve dislocation was present in 29 patients (33%), and nerve atrophy was present in 21 (24%) patients. Visualization of NVC on magnetic resonance imaging scans was not associated with outcome. The two variables associated with poor outcome were a large vessel contacting the nerve with brainstem deformation and proximal NVC. Nerve atrophy and nerve dislocation were not associated with outcome. CONCLUSION: The visualization of NVC, nerve atrophy, and nerve dislocation on magnetic resonance imaging scans was not associated with pain outcome. A large vessel compressing the nerve and deforming the brainstem and proximal NVC were associated with a lesser pain control.

Surgery for high-grade gliomas in a developing country: survival estimation using a simple stratification system.

BACKGROUND: In spite of great technological advances in diagnostic and therapeutic tools, survival in patients with HGG has not changed significantly in the last years. Judicious management in each case needs survival estimation after surgery. We used a simple stratification system evaluating the histology, patient's age, and the KPS. METHODS: We retrospectively made an analysis of survival in 103 patients with HGG operated in a 10-year period (1990--1999). Three significant prognostic variables were studied: histology, patient's age, and KPS. The BS-MG was calculated, adding the partial score (0 or 1) obtained for each variable. This score ranges from 0 (worse condition) to 3 (best condition). RESULTS: Overall, MS was 12 months. For glioblastoma multiforme, AA, and ODS, it was 10, 20, and 19 months, respectively (P = .0001). Patients 44 years old or younger had an MS of 28 months, higher than 10 months for patients older than 45 years (P < .0001). Median survival was 20 months for patients with KPS 80 or higher, and 9 months for those with KPS 70 or lower (P = .02). It was 3.5 months in patients with BS-MG = 0, 9 months for BS-MG = 1, 22 months for BS-MG = 2, and 55 months for BS-MG = 3 (P < .0001.). CONCLUSIONS: Survival presented here is comparable with those previously reported despite lacking the most sophisticated surgical technique. The stratification score that includes the 3 most important variables for survival seems to be simple and reliable for survival estimation.

[Diagnosis and treatment of brain metastasis]. / Diagnóstico y tratamiento de las metástasis encefálicas.

Cerebral metastasis occur in 20 to 30 percent of patients with systemic cancer and are the most common type of intracranial tumor. The median survival of untreated patients is one month with a slightly longer survival in those treated with steroids. Patients treated with whole brain radiation therapy survive between 3 to 6 months. In selected cases survival can increase to 10 to 12 months with combination of surgery and radiotherapy or stereotactic radiosurgery alone or associated to radiotherapy. Most brain metastasis arise from lung, breast and melanomas. The most important criteria for selecting patients who will benefit from surgery or stereotactic radiosurgery are a Karnofsky score of 70 or more, systemic control of the cancer and absence of leptomeningeal involvement. Surgery is indicated in patients with a single lesion located in an accessible zone and stereotactic radiosurgery is indicated for lesions up to 3 cm of diameter, and in patients with up to 3 or 4 metastasis, no matter their location. The survival benefit of chemotherapy in brain metastasis has not been demonstrated.

Radiosurgery for trigeminal neuralgia.

Radiosurgery has recently emerged as a suitable treatment of pharmacologically resistant idiopathic trigeminal neuralgia. Results and complications of this treatment are related to parameters of the dosimetry, i.e. the dose and the target. We found that the irradiation dose delivered to the brainstem, the distance between the target and the brainstem, and the occurrence of facial numbness after radiosurgery are related to a better pain outcome.

Pathological findings following trigeminal neuralgia radiosurgery.

Autopsy, 3D MRI and histopathological findings are presented in a patient who had suffered from trigeminal neuralgia and was treated two times by radiosurgery. The first treatment was performed with 90 Gy at the distal part of the nerve. Because of recurrent pain, a second irradiation was carried out delivering 70 Gy at a more proximal segment of the nerve 10 months later. The patient died from a hemorrhagic stroke 26 days following the second intervention. Autopsy revealed a neurovascular conflict close to the second radiosurgery shot. Histopathology demonstrated acute and chronic stage radiation-induced lesions in the trigeminal nerve.

Radiosurgery for treatment of brain metastases: estimation of patient eligibility using three stratification systems.

PURPOSE: To compare three patient stratification systems predicting survival: recursive partitioning analysis (RPA), score index for radiosurgery in brain metastases (SIR), and a proposed basic score for brain metastases (BS-BM). METHODS AND MATERIALS: We analyzed the outcome of 110 patients treated with Leksell Gamma Knife radiosurgery between December 1999 and January 2003. The BS-BM was calculated by evaluating three main prognostic factors: Karnofsky performance status, primary tumor control, and presence of extracranial metastases. RESULTS: The median survival was 27.6 months for RPA Class I, 10.7 months for RPA Class II, and 2.8 months for RPA Class III (p <0.0001). Using the SIR, the median survival was 27.7, 10.8, 4.6, and 2.4 months for a score of 8-10, 5-7, 4, and 0-3, respectively (p <0.0001). The median survival was undefined in patients with a BS-BM of 3 (55% at 32 months) and was 13.1 months for a BS-BM of 2, 3.3 months for a BS-BM of 1, and 1.9 months for a BS-BM of 0 (p <0.0001). The backward elimination model in multivariate Cox analysis identified SIR and BS-BM as the only two variables significantly associated with survival (p = 0.031 and p = 0.043, respectively). CONCLUSION: SIR and BS-BM were the most accurate for estimating survival. They were specific enough to identify patients with short survival (SIR 0-3 and BS-BM 0). Because of it simplicity, BS-BM is easier to use.

Use of stereotactic PET images in dosimetry planning of radiosurgery for brain tumors: clinical experience and proposed classification.

UNLABELLED: We developed a technique that allows the routine integration of PET in stereotactic neurosurgery, including radiosurgery. We report our clinical experience with the combined use of metabolic (i.e., PET) and anatomic (i.e., MRI and CT) images for the radiosurgical treatment of brain tumors. We propose a classification describing the relative role of the information provided by PET in this multimodality image-guided approach. METHODS: Between December 1999 and March 2003, 57 patients had stereotactic PET as part of their image acquisition for the planning of gamma knife radiosurgery. Together with stereotactic MRI and CT, stereotactic PET images were acquired on the same day using either (18)F-FDG or (11)C-methionine. PET images were imported in the planning software for the radiosurgery dosimetry, and the target volume was defined using the combined information of PET and MRI or CT. To analyze the specific contribution of the PET findings, we propose a classification that reflects the strategy used to define the target volume. RESULTS: The patients were offered radiosurgery with PET guidance when their tumor was ill-defined and we anticipated some limitation of target definition on MRI alone. This represents 10% of the radiosurgery procedures performed in our center during the same period of time. There were 40 primary brain lesions, 7 metastases, and 10 pituitary adenomas. Abnormal PET uptake was found in 62 of 72 targets (86%), and this information altered significantly the MRI-defined tumor in 43 targets (69%). CONCLUSION: The integration of PET in radiosurgery provides additional information that opens new perspectives for the optimization of the treatment of brain tumors.

Gamma knife surgery for idiopathic trigeminal neuralgia performed using a far-anterior cisternal target and a high dose of radiation.

OBJECT: Gamma knife surgery (GKS) has emerged as a suitable treatment of pharmacologically resistant idiopathic trigeminal neuralgia. The optimal radiation dose and target for this therapy, however, remain to be defined. The authors analyzed the results of GKS in which a high dose of radiation and a distal target was used, to determine the best parameters for this treatment. METHODS: The authors evaluated results in 47 patients who were treated with this approach. All patients underwent clinical and magnetic resonance imaging examinations at 6 weeks, 6 months, and 1 year post-GKS. Fifteen potential prognostic factors associated with favorable pain control were studied. The mean follow-up period was 16 months (range 6-42 months). The initial pain relief was excellent (100% pain control) in 32 patients, good (90-99% pain control) in seven patients, fair (50-89% pain control) in three patients, and poor (< 50% pain control) in five patients. The actuarial curve of pain relief displayed a 59% rate of excellent pain control and a 71% excellent or good pain control at 42 months after radiosurgery. Radiosurgery-induced facial numbness was bothersome for two patients and mild for 18 patients. Three prognostic factors were found to be statistically significant factors for successful pain relief: a shorter distance between the target and the brainstem, a higher radiation dose delivered to the brainstem, and the development of a facial sensory disturbance after radiosurgery. CONCLUSIONS: To optimize pain control and minimize complications of this therapy, we recommend that the nerve be targeted at a distance of 5 to 8 mm from the brainstem.

Use of the Leksell gamma knife C with automatic positioning system for the treatment of meningioma and vestibular schwannoma.

OBJECT: The authors report their experience using the Leksell gamma knife C (GK-C) for the treatment of meningioma and vestibular schwannoma (VS). METHODS: In December 1999, the first commercially available clinical GK-C was installed at the Université Libre de Bruxelles (Erasme Hospital, Brussels, Belgium). In January 2000, the system was upgraded and equipped with the automatic positioning system (APS). Between February 2000 and February 2003, the APS-equipped GK-C was used to perform 532 radiosurgical treatments, including those in 97 meningiomas and 101 VSs. Meningioma and VS represent 18 and 19%, respectively, of lesions in patients treated with GK-C at the authors' center. The mean number of isocenters per lesion was 9.5 (range 1-36): 18.1 (range 1-36) for meningioma and 12.8 (range 1-27) for VS. In 77.6% of the cases, the authors used a single helmet of collimators (55.5% in meningioma and 74.3% in VS). The most frequently used collimator size was 4 mm (46.7%). Whereas it was 4 mm in cases of VS (64.3%), it was 8 mm in cases of meningioma (41.6%). The APS could be used in 86% of the cases, either alone (79%) or in combination with trunnions (7%). There was a difference in the APS-based treatment success rate in meningiomas (85%) and VSs (94%). A significant difference was also noted in the conformity of the radiosurgical treatments between the two lesions. CONCLUSIONS: The APS-equipped GK-C represents an evolutionary step in radiosurgery. It requires adjustments by the treating team for its specific limitations, which vary among indications, as exemplified by the differences inherent between meningioma and VS in this series.

The integration of metabolic imaging in stereotactic procedures including radiosurgery: a review.

OBJECT: The authors review their experience with the clinical development and routine use of positron emission tomography (PET) during stereotactic procedures, including the use of PET-guided gamma knife radiosurgery (GKS). METHODS: Techniques have been developed for the routine use of stereotactic PET, and accumulated experience using PET-guided stereotactic procedures over the past 10 years includes more than 150 stereotactic biopsies, 43 neuronavigation procedures, and 34 cases treated with GKS. Positron emission tomography-guided GKS was performed in 24 patients with primary brain tumors (four pilocytic astrocytomas, five low-grade astrocytomas or oligodendrogliomas, seven anaplastic astrocytomas or ependymomas, five glioblastomas, and three neurocytomas), five patients with metastases (single or multiple lesions), and five patients with pituitary adenomas. CONCLUSIONS: Data obtained with PET scanning can be integrated with GKS treatment planning, enabling access to metabolic information with high spatial accuracy. Positron emission tomography data can be successfully combined with magnetic resonance imaging data to provide specific information for defining the target volume for the radiosurgical treatment in patients with recurrent brain tumors, such as glioma, metastasis, and pituitary adenoma. This approach is particularly useful for optimizing target selection for infiltrating or ill-defined brain lesions. The use of PET scanning contributed data in 31 cases (93%) and information that was specifically utilized to adapt the target volume in 25 cases (74%). It would seem that the integration of PET data into GKS treatment planning may represent an important step toward further developments in radiosurgery: this approach provides additional information that may open new perspectives for the optimization of the treatment of brain tumors.

Criterios quirúrgicos de neurocirujanos de latinoamérica en hematomas intracerebrales espontáneos / Surgical criteria of latinamerican neurosurgeons in spontaneous intracerebral hematomas

La cirugía en hematomas intracerebrales espontáneos es aún un tema de gran controversia pese a los numerosos estudios publicados en la literatura. Se realizó una encuesta en el XXVII Congreso Latinoamericano de Neurocirugía, realizado en Honduras en el mes de octubre de 1996, en donde se preguntó sobre criterios empleados en la indicación de cirugía por los encuestados. Fueron analizadas las siguientes variables: localización, lateralidad, tamaño, nivel de conciencia y desviación de línea media en la tomografía computada (TC). La encuesta fue respondida por 118 neurocirujanos pertenecientes a 18 países latinoamericanos, 82 por ciento titulados y 18 por ciento residentes. Se encontraron algunas tendencias como operar los hematomas talámicos, controvertida la cirugía en hematomas putaminales, operar a los pacientes en sopor con volumen del hematoma con volumen del hematoma entre 20 y 80 cc y con desviación de la línea media en la TC mayor de 5 mm. Pese a tales tendencias generales no se encontró uniformidad de criterios entre los encuestados