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Introduction: Stereotactic brain biopsies are essential for obtaining tissue samples from brain lesions, crucial for comprehensive histological analysis and subsequent adjuvant therapies. While most biopsies target supratentorial lesions, those involving the posterior fossa are less frequent but pose significant technical and surgical challenges, necessitating careful patient management. Methods: We present our experience with stereotactic biopsies of the posterior fossa using the Leksell Vantage frame (Elekta, Stockholm, Sweden) and the ZD Inomed frame (Inomed Medizintechnik GmbH, Emmendingen, Germany). For the ZD frame, we either mounted it upside down or employed a frontal approach, while for the Leksell Vantage frame, we utilized a reverse x-axis orientation. Planning was based on 3-T MRI scans and preoperative MRI merged with stereotactic CT for coordinate generation. Results: From 2006 to 2023, we performed 25 stereotactic biopsies of the posterior fossa in our department—9 with the ZD Inomed frame and 16 with the Leksell Vantage frame. The cohort included 14 male and 11 female patients, with an average age of 60.6 years (range 36—80 years). The average surgery duration was shorter with the Leksell Vantage frame (32.6 min vs. 44.8 min, p = 0.05). The average length of the planned trajectory was 41.7 mm for the Leksell Vantage frame and 52.2 mm for the ZD Inomed frame. Postoperativ bleeding occurred in two cases—one managed conservatively, the other required surgical intervention. Additionally, two other cases presented new postoperative focal neurological deficit. The overall mortality rate was 34.8% and a 40-day postoperative mortality rate of 13.0%. Conclusion: Our experience demonstrates that stereotactic biopsies of lesions in the posterior fossa can be effectively managed with different frame systems, though they present a higher degree of complexity. Notably, the Leksell Vantage frame was associated with a significantly shorter surgery duration. This technical note provides valuable insights and detailed technical guidance for neurosurgeons facing similar challenges. [ABSTRACT FROM AUTHOR]

Background: Stereotactic approaches to diffuse intrinsic pontine gliomas (DIPGs) remain essential due to advances in molecular biology and management, necessitating tissue sampling. Here we present an effective technique with a biopsy by robot-assisted transcerebellar approach. Method: Our procedure was performed using the ROSA robotic system and the OARM CT scan, which provided stereotactic conditions for this transcerebellar approach to brainstem lesions. Conclusion: The robot-assisted transcerebellar stereotactic approach remains essential to provide complications for biopsy of brainstem lesions. [ABSTRACT FROM AUTHOR]

Purpose: The gold standard for diagnostics in primary central nervous system lymphoma (PCNSL) is histopathological diagnosis after stereotactic biopsy. Yet, PCNSL has a multidisciplinary diagnostic work up, which associated with diagnostic delay and could result in treatment delay. This article offers recommendations to neurosurgeons involved in clinical decision-making regarding (novel) diagnostics and care for patients with PCNSL with the aim to improve uniformity and timeliness of the diagnostic process for patients with PCNSL. Methods: We present a mini review to discuss the role of stereotactic biopsy in the context of novel developments in diagnostics for PCNSL, as well as the role for cytoreductive surgery. Results: Cerebrospinal fluid-based diagnostics are supplementary and cannot replace stereotactic biopsy-based diagnostics. Conclusion: Histopathological diagnosis after stereotactic biopsy of the brain remains the gold standard for diagnosis. Additional diagnostics should not be a cause of diagnostic delay. There is currently no sufficient evidence supporting cytoreductive surgery in PCNSL, with recent studies showing contradictive data and suboptimal study designs. [ABSTRACT FROM AUTHOR]

Objective: Lesions of the posterior fossa (brainstem and cerebellum) are challenging in diagnosis and treatment due to the fact that they are often located eloquently and total resection is rarely possible. Therefore, frame-based stereotactic biopsies are commonly used to asservate tissue for neuropathological diagnosis and further treatment determination. The aim of our study was to assess the safety and diagnostic success rate of frame-based stereotactic biopsies for lesions in the posterior fossa via the suboccipital-transcerebellar approach. Methods: We performed a retrospective database analysis of all frame-based stereotactic biopsy cases at our institution since 2007. The aim was to identify all surgical cases for infratentorial lesion biopsies via the suboccipital-transcerebellar approach. We collected clinical data regarding outcomes, complications, diagnostic success, radiological appearances, and stereotactic trajectories. Results: A total of n = 79 cases of stereotactic biopsies for posterior fossa lesions via the suboccipital-transcerebellar approach (41 female and 38 male) utilizing the Zamorano-Duchovny stereotactic system were identified. The mean age at the time of surgery was 42.5 years (± 23.3; range, 1–87 years). All patients were operated with intraoperative stereotactic imaging (n = 62 MRI, n = 17 CT). The absolute diagnostic success rate was 87.3%. The most common diagnoses were glioma, lymphoma, and inflammatory disease. The overall complication rate was 8.7% (seven cases). All patients with complications showed new neurological deficits; of those, three were permanent. Hemorrhage was detected in five of the cases having complications. The 30-day mortality rate was 7.6%, and 1-year survival rate was 70%. Conclusions: Our data suggests that frame-based stereotactic biopsies with the Zamorano-Duchovny stereotactic system via the suboccipital-transcerebellar approach are safe and reliable for infratentorial lesions bearing a high diagnostic yield and an acceptable complication rate. Further research should focus on the planning of safe trajectories and a careful case selection with the goal of minimizing complications and maximizing diagnostic success. [ABSTRACT FROM AUTHOR]

Purpose: With the increasing role of molecular genetics in the diagnostics of intracranial tumors, delivering sufficient representative tissue for such analyses is of paramount importance. This study explored the rate of successful diagnosis after frame-based stereotactic biopsies of intracranial lesions. Methods: Consecutive patients undergoing frame-based stereotactic biopsies in 2020 and 2021 were included in this retrospective analysis. Cases were classified into three groups: conclusive, diagnosis with missing molecular genetics (MG) data, and inconclusive neuropathological diagnosis. Results: Of 145 patients, a conclusive diagnosis was possible in n = 137 cases (94.5%). For 3 cases (2.0%), diagnosis was established with missing MG data. In 5 cases (3.5%), an inconclusive (tumor) diagnosis was met. Diagnoses comprised mainly WHO 4 glioblastomas (n = 73, 56%), CNS lymphomas (n = 23, 16%), inflammatory diseases (n = 14, 10%), and metastases (n = 5, 3%). Methylomics were applied in 49% (n = 44) of tumor cases (panel sequencing in n = 28, 30% of tumors). The average number of specimens used for MG diagnostics was 5, while the average number of specimens provided was 15. In a univariate analysis, insufficient DNA was associated with an inconclusive diagnosis or a diagnosis with missing MG data (p < 0.001). Analyses of planned and implemented trajectories of cases with diagnosis with missing MG data or inconclusive diagnosis (n = 8) revealed that regions of interest were reached in almost all cases (n = 7). Conclusion: Although stereotactic frame-based biopsies deliver a limited amount of tissue, they bear high histopathological and molecular genetic diagnostic yields. Given the proven surgical precision of the planned biopsy trajectories, optimizing surveyed lesion regions could help improve the rate of conclusive diagnoses. [ABSTRACT FROM AUTHOR]

Background: Stereotactic biopsies for brainstem lesions are frequently performed to yield an accurate diagnosis and help guide subsequent management. In this study, we summarize our experience with different stereotactic approaches to brainstem lesions of different locations and discuss possible implications for safety and diagnostic yield. Methods: We retrospectively analyzed 23 adult patients who underwent a stereotactic biopsy for brainstem lesions between October 2011 and December 2019. Depending on the location supra- or infratentorial, trajectories were planned. We assessed the postoperative complications during the hospital stay as well as the diagnostic yield. Results: A supratentorial transfrontal approach was used in 16 (70%) cases, predominantly for lesions in the midbrain, upper pons, and medulla oblongata. An infratentorial, transcerebellar-transpeduncular approach was used in 7 (30%) cases mainly for lesions within the lower pons. All biopsies were confirmed to represent pathological tissue and a definitive diagnosis was achieved in 21 cases (91%). Three patients (13%) had transient weakness in the contralateral part of the body in the immediate postoperative period, which improved spontaneously. There was no permanent morbidity or mortality in this series of patients. Conclusion: Lesions of various locations within the brainstem can be successfully targeted via either a supratentorial transfrontal or an infratentorial transcerebellar transpeduncular approach. Our high diagnostic yield of over 90% and the low rate of complications underlines the diagnostic importance of this procedure in order to guide the medical management of these patients. [ABSTRACT FROM AUTHOR]

Background: Open and stereotactic transfrontal or transcerebellar approaches have been used to biopsy brainstem lesions. Method: In this report, a stereotactic posterior and midline approach to the distal medulla oblongata under microscopic view is described. The potential advantages and limitations are discussed, especially bilateral damage of the X nerve nuclei. Conclusion: This approach should be considered for biopsy of distal and posterior lesions. We strongly recommend the use of direct microscopic view to identify the medullary vessels, confirm the midline entry point, and avoid potential shift of the medulla. Further experience is needed to confirm safety and success rate of this approach. [ABSTRACT FROM AUTHOR]

Objectives: We evaluated the feasibility, safety, and diagnostic yield of frame-based stereotactic biopsies (SB) in lesions located in deep-seated and midline structures of the brain to analyze these parameters in comparison to other brain areas. Patients and methods: In a retrospective, tertiary care single-center analysis, we identified all patients who received SB for lesions localized in deep-seated and midline structures (corpus callosum, basal ganglia, pineal region, sella, thalamus, and brainstem) between January 1996 and June 2015. Study participants were between 1 and 82 years. We evaluated the feasibility, procedural complications (mortality, transient and permanent morbidity), and diagnostic yield. We further performed a risk analysis of factors influencing the latter parameters. Chi-square test, Student t test, and Mann-Whitney rank-sum test were used for statistical analysis. Results: Four hundred eighty-nine patients receiving 511 SB procedures (median age 48.5 years, range 1–82; median Karnofsky Performance Score 80%, range 50–100%, 43.8% female/56.2% male) were identified. Lesions were localized in the corpus callosum (29.5%), basal ganglia (17.0%), pineal region (11.5%), sella (7.8%), thalamus (4.3%), brainstem (28.8%), and others (1.1%). Procedure-related mortality was 0%, and permanent morbidity was 0.4%. Transient morbidity was 9.6%. Histological diagnosis was possible in 99.2% (low-grade gliomas 16.2%, high-grade gliomas 40.3%, other tumors in 27.8%, no neoplastic lesions 14.5%, no definitive histological diagnosis 0.8%). Only the pons location correlated significantly with transient morbidity (p < 0.001). Conclusion: In experienced centers, frame-based stereotactic biopsy is a safe diagnostic tool with a high diagnostic yield also for deep-seated and midline lesions. [ABSTRACT FROM AUTHOR]

Stereotactic needle biopsy, a standard of care for acquiring deep-seated pathology, has limitations and risks in some situations. We present an uncommon case with basal ganglia dematiaceous mycetoma. Due to the firm consistency of the lesion, the initial stereotactic needle biopsy failed to provide a diagnosis. In a second operation, transtubular excisional biopsy was successfully performed to remove the entire mycetoma. We reviewed recent case series of transtubular approaches to deep-seated brain lesions and suggest this method could be a rescue for a non-diagnostic stereotactic needle biopsy and even may be the approach of choice in some cases. [ABSTRACT FROM AUTHOR]

Stereotactic brain biopsies for histopathological diagnosis are a common technique in case of intracranial lesions, particularly in those not amenable for resection. Tumor seeding alongside the surgical trajectory after fine-needle aspiration is a known problem in several visceral tumors. Whereas in these cases a complete resection of the biopsy trajectory may later be performed, this strategy is not feasible in stereotactic brain biopsy. We report a case of tumor seeding along the entire biopsy tract after stereotactic biopsy of a brainstem metastasis. A 68-year-old male patient with a concomitantly diagnosed kidney lesion presented with a singular lesion in the brainstem. After confirmation of metastasis by stereotactic biopsy, stereotactic radiosurgery (SRS) was applied. The primary tumor was treated by laparoscopic nephrectomy. Three months after SRS, the patient presented with a secondary clinical deterioration for only a few weeks. The MRI scan showed tumor seeding along the entire biopsy tract. Salvage treatment including hypofractionated stereotactical irradiation and seven cycles of bevacizumab was administered to obtain symptom control. Massive seeding of tumor after stereotactic biopsy accordingly rare, taking into account that stereotactic biopsy is a very common neurosurgical intervention. Nonetheless, we think that the potential risk has to be kept in mind, as it might be neglected. [ABSTRACT FROM AUTHOR]

Background: Biopsies of clival lesions are usually performed, under general anaesthesia, through an anterior endoscopic approach or, alternatively, through a trans-nasal or trans-oral stereotactic approach. Methods: A 57-year-old man with a symptomatic osteolytical lesion of the clivus, who refused general anaesthesia, underwent a sterotactically guided biopsy of the lesion by an antero-lateral approach through the temporal and sphenoid bones. Results: Biopsy was successfully performed and the resulting diagnosis was myeloma. The patient was comfortable during and after surgery and there were no complications. Conclusions: The present stereotactic antero-lateral approach to the biopsy of the upper clivus can be considered an useful adjunct to the current trans-oral and transnasal approaches that often require general anaesthesia. [ABSTRACT FROM AUTHOR]

Background: Frame-based stereotactic procedures are the gold standard because of their superior stereotactic accuracy. The procedure used to be in multiple steps and was especially cumbersome and hazardous in intubated patients. A single-step procedure using intraoperative CT was created to optimize the procedures. Methods: A combined fixation and low profile frame holder was designed for the operating table, allowing positioning for the scanning procedure immediately followed by the surgical biopsy procedure with the same positioning and head fixation. For placement of depth electrodes immediate CT control of positioning was feasible. Results: In the first 8 months the procedure was successfully used 65 times including 8 times in pediatric cases. The procedure duration in awake patients was on average 81 min (range 33 to 202) and in intubated patients (children) on average 89 min (median 89, 78-100). Discussion: This study demonstrates that frame-based stereotactic procedures in all brain locations are a feasible and practical technique with improved workflow and added patient safety and comfort. [ABSTRACT FROM AUTHOR]

Background: Venous air embolism (VAE) is a serious potential complication of neurosurgical procedures. Stereotactic biopsies can also cause VAE; therefore, we evaluated VAE patients to call attention to the risk of VAE associated with stereotactic biopsies. Methods: In this report, symptomatic VAE was defined as paroxysmal coughing with associated symptoms. Air in the dural sinus, cortical vein and/or pterygoid plexus on postoperative computed tomography (CT) scans was considered to be a radiographic VAE. Results: Three patients developed symptomatic VAE following 36 stereotactic biopsies, and the incidence of symptomatic VAE was 8.3 % (3/36). There were five patients with evidence of radiographic VAE on postoperative CT scans, with an incidence of 13.8 % (5/36). A high angle of the head seemed to be associated with VAE, allowing air to flow into the central venous system. Conclusions: The present report emphasizes that VAE should be recognized as an important adverse effect of stereotactic biopsies because VAE occasionally requires additional treatment and/or termination of surgery. Surgeons must be aware of the possibility of VAE, especially when it is necessary to position the patient's head at a high angle. [ABSTRACT FROM AUTHOR]

Background: Frameless stereotactic biopsies are replacing frame-based stereotaxy as a diagnostic approach to brain lesions. In order to avoid a sampling bias or negative histology, multiple specimens are often taken. This in turn increases the risk of hemorrhagic complications. Objective: We present the use of 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX fluorescence in frameless stereotaxy to improve the procedure duration and yield, and thereby reduce the risk of complications. Methods: Patients with suspected high-grade brain tumors are given 5-ALA 4 h prior to stereotactic biopsy. The biopsy needle is guided to the target using frameless stereotaxy based either on preoperative images or combined with intraoperative MRI sequences. The specimen is illuminated with blue light to look for fluorescence. In case of a positive fluorescence within the tissue sample, no frozen sections are obtained, and no further specimens are taken. Results: The samples of 13 patients revealed a positive fluorescence and were histologically confirmed as malignant or high-grade brain neoplasms. four cases were fluorescence-negative, requiring frozen section confirmation and/or multiple samples. In theses cases histology was either nonspecific gliotic changes or low-grade tumors. There were no complications related to the additional use of 5-ALA. Conclusion: 5-ALA fluorescence in stereotactic biopsies can increase the safety and accuracy of these procedures by reducing sampling errors and eliminating the need for multiple samples and/or frozen section verification, creating a more accurate, faster and safer procedure for cases of suspected malignant or high-grade brain tumors situated in deep or eloquent areas. [ABSTRACT FROM AUTHOR]

Objective: Recent improvements in imaging-based diagnosis, the broader application of neuroendoscopic techniques and advances in open surgery techniques mean that the need for stereotactic biopsies in the management of pineal region tumours must be reevaluated. The primary aim of this retrospective study was to establish whether stereotactic biopsy is still of value in the modern management of pineal region tumours. Methods: From 1985 to 2009, 88 consecutive patients underwent a stereotactic biopsy in our institution (51 males and 37 females; median age at presentation 30; range 2-74). Results: Accurate tissue diagnoses were obtained in all but one case (i.e. 99%). In one case (1%), three distinct stereotactic procedures were necessary to obtain a tissue diagnosis. There was no mortality or permanent morbidity associated with stereotactic biopsy. One patient (1%) presented an intra-parenchymal hematoma but no related clinical symptoms. Five patients (6%) presented transient morbidity, which lasted for between 2 days and 3 weeks after the biopsy. Conclusions: To guide subsequent treatment, we believe that histological diagnosis is paramount. Stereotactic biopsies are currently the safest and the most efficient way of obtaining this essential information. Recent improvements in stereotactic technology (particularly robotic techniques) appear to be very valuable, with almost no permanent morbidity or mortality risk and no decrease in the accuracy rate. In our opinion, other available neurosurgical techniques (such as endoscopic neurosurgery, stereotactic neurosurgery and open microsurgery) are complementary and not competitive. [ABSTRACT FROM AUTHOR]

Background. The aim of this study was to compare the diagnostic accuracy of 1H MR-spectroscopy versus image-guided stereotactic biopsy. Method. A cohort of 83 consecutive patients with a broad spectrum of brain lesions were examined. Prior to stereotactic biopsy, the patients were subjected to 1H MR-spectroscopy examination. Diagnostic accuracy of 1H MR-spectroscopy and image guided stereotactic biopsy was determined for the largest diagnostic subgroups. Each diagnostic procedure was tested for concordance in every subgroup. Findings. The subgroups of patients comprised: low grade glioma, high grade glioma (grades III and IV), lymphoma and metastasis. For the sensitivity of 1H MR-spectroscopy ranged from 87.7 in high grade glioma to 92.3% in metastasis and for specificity from 93.3% for high grade glioma to 100% in low grade glioma. The highest positive predictive value of 100% was reached in the subgroup of low grade glioma. The highest negative predictive value was reached in lymphoma and metastasis, 100%. The kappa values were highly significant for all comparisons ( p<0.001). The co-efficient ranged from 0.68 to 0.84. It was lowest in assessing high grade glioma and highest in lymphoma. Conclusion. Compared with each other 1H MR-spectroscopy and image-guided stereotactic biopsy showed a moderate to good, statistically highly significant concordance. In patients in whom operation is at an increased risk e.g., due to severe medical illness, 1H MR-spectroscopy as a noninvasive procedure may be sufficient to assess the diagnosis. [ABSTRACT FROM AUTHOR]

A case of low grade astrocytoma (WHO grade II) localised in the pituitary stalk is reported in a 46 year old female who presented with central diabetes insipidus. Six-monthly magnetic resonance imaging was use to determine the progression of the lesion. The patient had a stereotactic biopsy of the lesion 18 months after the initial presentation. The diagnosis was established with the aid of immunohistochemistry. We emphasize the importance of MRI before initiating therapy to evaluate the pituitary stalk lesion and the effectiveness of stereotactic biopsy in securing tissue diagnosis without additional deficit. [ABSTRACT FROM AUTHOR]

A 29-year-old man presented with diplopia, dysarthria, anisocoria, oculomotor nerve paralysis, abducens nerve paralysis, right facial palsy, and spastic hemiparetic gait. Magnetic resonance imaging (MRI) showed a homogenously enhanced mass in the midbrain. MRI-guided stereotactic biopsy was performed, and the histologic diagnosis was pure germinoma. The tumor disappeared after chemotherapy and radiotherapy. Germinoma should be included in the differential diagnosis of midbrain lesions in young adults. MRI-guided stereotactic biopsy provided a helpful diagnostic clue in a patient with a midbrain lesion. [ABSTRACT FROM AUTHOR]

Object. The aim of this study was to document the possible role of Gamma Knife radiosurgery, suitable for the treatment of deep and well limited tumors, in the management of pineal parenchymal tumors (PPT). Population and methods. We reviewed retrospectively a series of 13 patients with PPT treated by Gamma Knife radiosurgery during 16 procedures. Mean age was 31 (range 10 to 74). Eight patients had pineocytomas (61.5%), and 5 had pineoblastomas (38.5%). Radiosurgery was performed alone in 6 cases, after partial microsurgical resection in 3 cases, in association with chemotherapy in 3 cases and following conventional fractionated radiotherapy in 1 case. The marginal dose to these tumors ranged from 11 to 20 Gy (mean 15 Gy). Results. With a mean follow-up of 34 months (range 6 to 88), all tumors responded to treatment and disappeared or ceased growing. Two patients with pineoblastoma had tumor size progression out of the initial target requiring several radiosurgery procedures. At the end of the follow-up period, 10 out of 12 patients were alive. Two patients with pineoblastoma died because of carcinomatous meningitis or tumor size progression. We observed no mortality or major morbidity related to radiosurgery. Conclusion. This study confirms that radiosurgery can be an effective and safe primary treatment modality for patients with pineocytomas. It should have a role in multimodality therapy which includes microsurgical resection, fractionated radiotherapy and chemotherapy for the management of malignant pineal tumors. [ABSTRACT FROM AUTHOR]

Object. Stereotactic brain biopsy is a routinely used technique for the diagnosis of brain lesions. Due to its minimally invasive nature, the potential risks associated with this procedure are sometimes underestimated. We have retrospectively analyzed the incidence of symptomatic and asymptomatic haemorrhagic complications associated with stereotactic biopsies. Various variables that may contribute to such complications have been retrospectively analyzed. Methods. Medical and radiological records of 355 consecutive patients who underwent a diagnostic stereotactic brain biopsy were reviewed. The incidence of haemorrhage was derived from a routine post-operative CT scan done within 90–120 minutes of the biopsy. Demographic, radiographic, pathological, and clinical data were also extracted and evaluated for their possible association with haemorrhagic complications. Results. Twenty-five patients (7%) experienced haemorrhagic complications associated with stereotactic biopsy, about half of whom (3.4%) were asymptomatic with no impact on the clinical course. Thirteen (3.6%) complications were symptomatic and two patients (0.6%) died. Lesions located in the brainstem were found to have a significantly higher rate of complications compared to other locations. No other variables, such as location, edema, number of biopsy specimens, or pre-existing neurological deficit showed a statistically significant impact on the incidence or severity of haemorrhage. Seven of the symptomatic complications occurred immediately post biopsy, but in six patients they developed within several hours and even days. The overall diagnostic yield of the biopsies was 93.8%, but was somewhat lower in patients experiencing a haemorrhagic complication. Conclusions. Stereotactic brain biopsy was associated with a low incidence of symptomatic haemorrhagic complications, morbidity and mortality, and a high diagnostic yield. About half of the haemorrhagic complications were asymptomatic. Lesions located in the brainstem had a higher rate of complications. No other clinical, radiographic, or pathological variables were found as predictors of increased risk for haemorrhage. [ABSTRACT FROM AUTHOR]

Summary ¶Background. Despite the rapid development in neuro-imaging over the past two decades, ring like contrast-enhancing lesions on CCT or MRI still may pose a diagnostic challenge. The main differential diagnoses of these lesions include metastatic carcinoma, high-grade glioma and brain abscess. Acute demyelination seldom turns out to be the underlying pathology. Method. Retrospective analysis was done on six patients with acute demyelination treated at our neurosurgical department between 1990 and 2001. Clinical, radiological, PET, intra-operative and histological findings were evaluated. Findings. In five patients, the diagnosis of acute demyelination was established by histopathological evaluation of stereotactic biopsy specimen, in the sixth patient following microsurgical extirpation of the lesion. Neuropathology revealed demyelination with the presence of myelin-phagocytosing macrophages. In addition, lymphocytic infiltrates were present. Symptoms and signs improved significantly after high-dose steroid therapy. Conclusions. Despite CNS tissue destruction, necrosis and cyst formation are not usually found in demyelinating disease, being rather more common in young patients with ring-like contrast-enhancing lesions on CCT and MRI. Though an incorrect diagnosis can lead to a potentially fatal therapeutic intervention, histological diagnosis should be made in all cases. Due to minimum morbidity, stereotactic biopsy is the method of choice to obtain representative specimens for histological diagnosis. Open microsurgery of these lesions is not indicated since conservative medical treatment with steroids results in a favourable outcome in most cases. [ABSTRACT FROM AUTHOR]

Background. The authors present a retrospective analysis of 308 computed tomography (CT)-guided stereotactic biopsies in 300 patients in order to evaluate the reliability and efficacy of the stereotactic biopsy for intracranial lesions. Method. All patients were suffering from undetermined intracranial lesions and treated at Seoul National University Hospital between January 1993 and December 1999. Age ranged from three to 79 years (mean 41); the male to female ratio was 180:120. All patients underwent CT-guided stereotactic biopsy for the histological verification and/or evacuation of the cyst using Riechert-Mundinger stereotactic system®. Findings. Histological diagnosis was made in 275 patients (diagnostic yield 91.7%). Diagnostic yield was better in group with frozen section examination during the stereotactic procedure than the group without it (p=0.01). Neoplastic lesions were more likely to be diagnosed in stereotactic biospy than non-neoplastic lesions (p=0.02). Among 30 patients who underwent craniotomy after the stereotactic biopsy, the histological diagnoses after the craniotomy were identical to those of the stereotactic biospy in 29 patients (diagnostic accuracy 96.7%). Two patients died within seven days after the stereotactic biopsy (mortality 0.6%). The postoperative new neurological deficit or aggravation of the neurological status was found in 19 patients, including transient cases of seven patients (permanent morbidity rate 3.9%). Histologically malignant gliomas and deeply-located lesions were the significant risk factors for the development of complications. In 148 cases, histological diagnosis of the stereotactic biopsy was different from the preoperative clinical diagnosis. Among these cases, the treatment plan was changed after stereotactic biopsy in 81 cases. Conclusions. Stereotactic biopsy for intracranial lesions is a reliable and relatively safe procedure. It is also a very efficacious method especially in patients who need histological confirmation for the treatment. [ABSTRACT FROM AUTHOR]

Summary Objective. To analyze prospectively the frequency and the risk of symptomatic and asymptomatic haemorrhage after image guided stereotactic biopsy of intra-axial brain tumours. Methods. The study was conducted within a time frame of 24 months (April 1998–April 2000). 326 patients (150 males, 176 females; mean age 56.8 years) were included and 345 computerized tomography (CT)-guided stereotactic biopsies were performed/supervised by a specialized stereotactic neurosurgeon. A modified Riechert Stereotaxy System and a workstation for multiplanar trajectory planning were used in all patients. Serial biopsies (median, 5 samples) were done with small forceps (diameter 1 mm), smear preparations of the biopsy specimens were intra-operatively examined. Frequency, size, and location of any detectable bleeding were analyzed by post-biopsy CT-scan investigation. For risk estimation, logistic regression analysis was performed. The chi-square statistic was used for comparative analysis of the study results with available data from the literature. Results. A conclusive tissue diagnosis could be achieved in 98%. Overall treatment morbidity was 3.1%. There was no mortality. Haemorrhage related morbidity was 0.9%. Age, Karnofsky score, mass effect of the tumour, tumour histology, tumour location and the number of specimens taken did not have any prognostic significance. The clinically silent bleeding rate was 9.6% and more often seen in patients with high grade gliomas (p=0.03). Both the silent and non-silent bleeding rate were significantly lower as compared to available prospective data in the literature. (p<0.01). Conclusion. Using multiplanar image guided trajectory planning, small biopsy forceps and intra-operative smear preparations the risk of major haemorrhage related morbidity after stereotactic brain tumour biopsy is extremely low (<1%) in experienced hands. [ABSTRACT FROM AUTHOR]

Summary Introduction. To add metabolic information during stereotactic biopsy target selection, the authors adopted proton chemical shift imaging (1H CSI)-directed stereotactic biopsy. Currently, proton single voxel spectroscopy (SVS) technique has been reported in stereotactic biopsy. We performed 1H CSI in combination with a stereotactic headframe and selected targets according to local metabolic information, and evaluated the pathological results. Patients and Method. The 1H CSI-directed stereotactic biopsy was performed in four patients. 1H CSI and conventional Gd-enhancement stereotactic MRI were performed simultaneously after the fitting of a stereotactic frame. After reconstructing the metabolic maps of N-acetylaspartate (NAA)/phosphocreatine (Cr), phosphocholine (Cho)/Cr, and Lactate/Cr ratios, focal areas of increased Cho/Cr ratio and Lac/Cr ratios were selected as target sites in the stereotactic MR images. Result.1H CSI is possible with the stereotactic headframe in place. No difficulty was experienced performing 1H CSI or making a diagnosis. Pathological samples taken from areas of increased Cho/Cr ratios and decreased NAA/Cr ratios provided information upon increased cellularity, mitoses and cellular atypism, and facilitated diagnosis. Pathological samples taken from areas of increased Lac/Cr ratio showed predominant feature of necrosis. Conclusion.1H CSI was feasible with the stereotactic headframe in place. The final pathological results obtained were concordant with the local metabolic information from 1H CSI. We believe that 1H CSI-directed stereotatic biopsy has the potential to significantly improve the accuracy of stereotactic biopsy targeting. [ABSTRACT FROM AUTHOR]

Chromosome analysis of brain tumours can provide important pathobiological data; however, cytogenetic tools are so far not routinely applied for diagnosis. In the present study 25 paraffin embedded stereotactic biopsies from 19 glioma patients were studied using in situ hybridization of chromosome #10 and #15 using biotinylated pericentromeric probes. Numerical changes of chromosome #10 are frequent alterations in glioblastoma. Quantification of chromosome #15 served as a control in order to exclude artificial monosomies or nonspecific changes. The number of chromosomes in at least 200 cells were counted for each specimen. 18 of 25 biopsies could be evaluated quantitatively. The small volume of probes was not a limiting factor for analysis. Quantification of “nonspecific” chromosome #15 revealed single spots in 22–41% of all cells in the 18 biopsies. Chromosome #10 showed single spots in a range between 34 and 44% of counted nuclei in 13/18 biopsies. In 5 out of 18 biopsies 51–60% monosomies were found; in this subgroup were 4 high grade gliomas. These cases were interpreted as monosomy of chromosome #10. The results demonstrate feasibility and quantitative evaluability of cytogenetic analysis in Stereotactic biopsy material using in situ hybridization. [ABSTRACT FROM AUTHOR]

Xenon-enhanced computerized tomography (XeCT) was performed on 14 consecutive adult patients presenting with seizures showing supratentorial non-enhancing radiologically uniform appearing low grade gliomas on CT/MR images. Pre-operative XeCT patterns were compared with postoperative histological diagnosis, grading and Ki67 proliferation indices (PI). After gross-total, subtotal resection or biopsy, 11 astrocytomas, 2 oligodendrogliomas and 1 oligo-astrocytoma were diagnosed and graded: Grade I: 2 patients (Ki67-PI=0.5-0.8), Grade I-II: 4 patients (Ki67-PI=0.3-1.5), Grade II: 3 patients (Ki67-PI=0.5-3.5), Grade II-III: 4 patients (Ki67-PI=3.8-6.8) and Grade III: 1 patient (Ki67-PI=5.2), (Kernohan Classification). Xenon CT studies revealed different flow patterns, correlating with the postoperative histological diagnosis, grading and proliferation indices: A tumour group with well defined, delayed, only minimally enhancing tumour area (5 patients, Grade I, I-II or II), a second group with less well defined low-flow-area borders and inhomogenous, strong enhancement within the tumour (4 patients, Grade II-III, III) and a third group with fast enhancing tumours was identified. The third pattern was exclusively shown in the 2 oligodendrogliomas (Grade I and II-III) and 1 oligo-astrocytoma (Grade II). The preliminary report identifies the Xenon enhanced CT as a beneficial pre-operative investigation for patients with radiologically uniform appearing suspected adult supratentorial low-grade gliomas, which may give information about the presence of anaplastic foci or oligodendroglial components. [ABSTRACT FROM AUTHOR]

A neurological complication occurs in 40-60% of HIV infected patients during the course of the disease. In 10-20% the neurological complication is the first manifestation of the HIV infection. A reliable neuropathological diagnosis is a prerequisite for a specifically selected treatment. While modern computer-assisted imaging techniques, such as computed tomography or magnetic resonance imaging, do possess a high sensitivity, they do not as a rule permit an unambiguous diagnosis. Between October 1989 and July 1994 we biopsied 38 HIV infected patients stereotactically. The indication for the biopsy was determined by having radiologically detectable lesions with no regression tendency in patients under antitoxoplasmosis therapy. In 89% an unambiguous diagnosis wa made based on the biopsy; 11 % of the biopsies were not diagnostic. For the most part, toxoplasmosis (31%) and progressive multifocal leucoencephalopathy (29%) were involved. 18% of the patients suffered from a non-Hodgkin lymphoma. The foci were primarily frontal (47%), parietal (21%) or localised in the basal ganglia area (11%). The result of the biopsy led to a change in treatment for 52% of the patients. Morbidity and mortality of the operation were 0%. The results or our research series are similar to other groups. It was shown that stereotactic brain biopsy is a safe and effective method for establishing a sound basis for treating the frequently life-threatening cerebral complications of AIDS. [ABSTRACT FROM AUTHOR]

In order to take advantage of the metabolic information provided by positron emission tomography (PET) in cases of brain tumour, we have developed a technique to integrate PET images routinely in the planning of stereotactic brain biopsy. We used stereotactic PET with [F]-labelled fluorodeoxyglucose (PET-FDG) in 38 patients undergoing brain biopsy. To evaluate the contribution of PET-FDG in guiding brain biopsy, we analyzed the diagnosis provided by the 78 Stereotactic trajectories obtained in these patients. We found that stereotactic PET-FDG seemed to provide more information in cases of anaplastic astrocytomas and glioblastomas than in low-grade gliomas. Our results also show that biopsy trajectories performed in areas where increased FDG uptake is found within the lesion boundaries always provide interpretable specimens; this was not the case for trajectories guided by CT only. Therefore, the routine integration PET-FDG in the planning of stereotactic brain biopsy may lead to a reduction in sampling. Recently, we also tested consecutive stereotactic PET with [C]-labelled methionine (PET-Met) and PET-FDG. This technique allowed us to compare accurately the tumoural glucose metabolism and protein synthesis. Our results suggest that stereotactic PET may increase the diagnostic yield of brain biopsy and may improve the understanding of PET in neuro-oncology. [ABSTRACT FROM AUTHOR]

Diagnosis and treatment of tumours and vascular malformations in the region of the pineal gland continue to challenge the neurosurgeon's skill. Due to vital vascular and brain structures in the region, microsurgical removal of such masses is often impossible. During the past nine years, we have managed 47 patients with pineal region mass lesions using stereotactic techniques for diagnosis and treatment. In order to determine further therapeutic options, 15 patients underwent stereotactic biopsy of pineal region tumours. In all patients, the histologic diagnosis obtained served to direct further therapy. Thirty-two patients were treated with stereotactic radiosurgery for pineal region tumours or vascular malformations. During the follow-up period, one patient underwent delayed microsurgical resection of a midbrain angiographically occult vascular malformation. No other patient required microsurgical intervention after a stereotactic procedure. In all 47 patients, no significant morbidity or mortality occurred after stereotactic biopsy or radiosurgery. Empiric treatment of pineal region tumours with fractionated radiation therapy is no longer warranted. Image-guided stereotactic technology provides a safe method to accurately diagnose and effectively treat selected pineal region masses. After definitive histologic diagnosis is established, proper treatment may be instituted. Options for treatment include stereotactic radiosurgery for selected tumours and vascular malformations, microsurgical resection of benign tumours or fractionated external beam radiation therapy for malignant germ cell and glial tumours. Stereotactic surgery should be the first option in the diagnosis and therapy of pineal region masses. [ABSTRACT FROM AUTHOR]

The use of a 20 MHz pulsed Doppler technique during stereotactic brain tumour biopsies is described. By means of a miniaturized ultrasonic probe the tissue planned for biopsy was investigated for vessel signals. Out of 41 patients, with this technique a flow-pulse curve in front of the biopsy cannula was registered in 14 cases. In 9 cases one pulse curve was determined and in 5 cases two or more flow curves were found, indicating the presence of arterial vessels. The depth of the vesses signal could be localized and this area avoided for biopsy sampling. In a series of 41 Stereotactic biopsies carried out in this way there was no intra-operative haemorrhage or postoperative haematoma. [ABSTRACT FROM AUTHOR]

Gliomatosis cerebri is rarely encountered and its intra vitam diagnosis has remained difficult. We present biopsy and autopsy findings in three cases that are representative of diffuse glioma, gliomatosis cerebri and diffuse glioblastosis, a modification of the subclassification proposed by Zülch. Stereotactic biopsy in conjunction with nuclear magnetic resonance tomography (MRT) is recommended as the diagnostic procedure in suspected cases. Immunohistochemical examination with a panel of neuroectodermal markers is helpful in the differential diagnosis but has to take into account that reactive astrocytes may be closely intermingled with the neoplastic glial cells. [ABSTRACT FROM AUTHOR]

A retrospective evaluation of the prognostic value of different parameters available in patients affected by glial tumours and submitted to serial stereotactic biopsy is presented. The series investigated includes thirty-three untreated patients with proven brain gliomas submitted to stereotactic biopsy. All patients have been clinically and neuroradiologically monitored for three years. The factors investigated belong either to the preoperative data (clinical history and symptomatology, CT pattern and volume of the lesion) or to histological and biological data obtained after the stereotactic biopsy. The results suggest the need of a multimodal prognostic evaluation in glial tumours and particularly stressed is the accuracy of prognostic indications derived from cell kinetic studies. [ABSTRACT FROM AUTHOR]

The monoclonal antibody Ki-67 has been tested as a marker of proliferating cells in 52 stereotactic brain tumour biopsies. The antibody reacts with a nuclear protein expressed in G,S, Gn and Mphases of the cell cycle. Using the immunoperoxidase technique on squash preparations the percentage of Ki-67 positive cells was determined as a fraction of the total number of tumour cells present. This Ki-67 index was in close correlation with the histological grade. Highest values were found in a pineal germinoma (46.3%) and in 3 primary cerebral non-Hodgkin lymphomas (mean 39.5%). Among the gliomas, the highest fraction of proliferating cells was seen in 2 anaplastic paediatric brain stem gliomas (mean 17.4%) and in an anaplastic ependymoma (12.5%). Anaplastic astrocytomas and glioblastomas varied considerably with mean values of 9.5% and 8%, respectively. To some extent this variability may reflect tumour heterogeneity which is more likely to manifest in small stereotactic samples than in large tissue specimens obtained during open surgery. Pilocytic astrocytomas, mixed gliomas and fibrillary astrocytomas had moderate to low percentages. Ki-67 staining of squash preparations can easily be performed on a rountine basis and is, in our experience, superior to frozen sections. This method allows the determination of the growth fraction of an individual tumour and could become an important additional criterion for the decision among alternative and potentially harmful therapeutic regimens. [ABSTRACT FROM AUTHOR]

The contribution of stereotactic biopsy (SB) in three pathological conditions; neoplastic disease, immunodeficiency states and degenerative cerebral atrophy, is reviewed. When craniotomy is contraindicated, SB is the most reliable method for demonstrating the neoplastic nature and the degree of malignancy of an intracranial space occupying lesion and may help to delineate it limits. In immunodepressed patients, SB is frequently used to differentiate tumours from opportunistic infections. In degenerative dementia, SB is susceptible of differentiating Alzheimer's disease from other degenerative conditions. [ABSTRACT FROM AUTHOR]

The modern neurodiagnostic techniques of MR imaging, CT scanning and angiography provide valuable morphological information that, although highly sensitive to tumour localisation, still lacks comparable specificity as to the exact histological nature of those lesions demonstrated. Biopsy remains necessary. To patients with potentially inoperable lesions or lesions best treated by chemotherapy or irradiation, modern techniques of neurosurgery now offer the option of precise stereotactic biopsy through small twist-drill burr holes as opposed to open biopsy. The interrelationships between MR, CT, angiography and stereotactic biopsy and their respective roles in the establishment of a definitive diagnosis are discussed. [ABSTRACT FROM AUTHOR]

Sixty-two consecutive CT-directed stereotactic biopsies were studied retrospectively to determine the value of the per-operative smear examination. Overall, in 69% of cases the immediate smear result agreed with the definitive histology. However, a smear diagnosis of malignant glioma was more reliable than that of metastasis (with 100% and 55% aggreement with the final result respectively). In those cases where the final histological diagnosis was that of malignant glioma, immediate smear preparations taken from the hypodense centre were found to be more reliable than those taken from the enhancing edge. [ABSTRACT FROM AUTHOR]

We present a simple but efficient technique for marking the site of a stereotactic biopsy. This is done by a radiopaque Barium impregnated silicone sphere, which is introduced through the stereotactic cannula and placed at the target point. This allows a postoperative check of the target point by computer tomography or Magnetic Resonance Imaging and offers a landmark for further stereotactic intervention as well as for planning of high precision radiotherapy. Moreover it gives information about the growing direction of a tumour. The silicone spheres are well tolerated; no complications have occured so far. [ABSTRACT FROM AUTHOR]