Neurosurgery Blog

Neurosurgery 70:283–294, 2012 DOI: 10.1227/NEU.0b013e31823020e6

Diffusion tensor (DT) imaging-based fiber tracking is a noninvasive magnetic resonance technique that can delineate the course of white matter fibers.

OBJECTIVE: To evaluate the accuracy and usefulness of this DT imaging-based fiber tracking for surgery in patients with gliomas near the pyramidal tract (PT).

METHODS: Subjects comprised 32 patients with gliomas near the PT. DT imagingbased fiber tracks of the PT were generated before and within 3 days after surgery in all patients. A tractography-integrated navigation system was used during the operation. Cortical and subcortical motor-evoked potentials (MEPs) were also monitored during resection to maximize the preservation of motor function. The threshold intensity for subcortical MEPs was examined by searching the stimulus points and changing the stimulus intensity. Minimum distance between the resection border and the illustrated PT was measured on postoperative tractography.

RESULTS: In all subjects, DT imaging-based tractography of the PT was successfully performed, preoperatively demonstrating the relationship between tumors and the PT. With the use of the tractography-integrated navigation system and intraoperative MEPs, motor function was preserved postoperatively in all patients. A significant correlation was seen between threshold intensity for subcortical MEPs and the distance between the resection border and PT on postoperative DT imaging.

CONCLUSION: DT imaging-based fiber tracking is a reliable and accurate method for mapping the course of subcortical PTs. Fiber tracking and intraoperative MEPs were useful for preserving motor function in patients with gliomas near the PT.

Neurosurgery 69:1272–1280, 2011 DOI: 10.1227/NEU.0b013e3182233e24

Convection-enhanced delivery of chemotherapeutics for the treatment of malignant glioma is a technique that delivers drugs directly into a tumor and the surrounding interstitium through continuous, low-grade positive-pressure infusion. This allows high local concentrations of drug while overcoming the limitations imposed by toxicity and the blood-brain barrier in systemic therapies that prevent the use of many potentially effective drugs.

OBJECTIVE: To examine the safety profile of a conventional chemotherapeutic agent, topotecan, via convection-enhanced delivery in the treatment of recurrent malignant gliomas and secondarily to assess radiographic response and survival.

METHODS: We performed a prospective, dose-escalation phase Ib study of the topoisomerase- I inhibitor topotecan given by convection-enhanced delivery in patients with recurrent malignant gliomas.

RESULTS: Significant antitumor activity as described by radiographic changes and prolonged overall survival with minimal drug-associated toxicity was demonstrated. A maximum tolerated dose was established for future phase II studies.

CONCLUSION: Topotecan by convection-enhanced delivery has significant antitumor activity at concentrations that are nontoxic to normal brain. The potential for use of this therapy as a generally effective treatment option for malignant gliomas will be tested in subsequent phase II and III trials

Neurosurgery 69:852–863, 2011 DOI: 10.1227/NEU.0b013e318225ea6b

The beneficial role of the extent of resection (EOR) in glioma surgery in correlation to increased survival remains controversial. However, common literature favors maximum EOR with preservation of neurological function, which is shown to be associated with a significantly improved outcome.

OBJECTIVE: In order to obtain a maximum EOR, it was examined whether high-field intraoperative magnetic resonance imaging (iMRI) combined with multimodal navigation contributes to a significantly improved EOR in glioma surgery.

METHODS: Two hundred ninety-three glioma patients underwent craniotomy and tumor resection with the aid of intraoperative 1.5 T MRI and integrated multimodal navigation. In cases of remnant tumor, an update of navigation was performed with intraoperative images. Tumor volume was quantified pre- and intraoperatively by segmentation of T2 abnormality in low-grade and contrast enhancement in high-grade gliomas.

RESULTS: In 25.9% of all cases examined, additional tumor mass was removed as a result of iMRI. This led to complete tumor resection in 20 cases, increasing the rate of grosstotal removal from 31.7% to 38.6%. In 56 patients, additional but incomplete resection was performed because of the close location to eloquent brain areas. Volumetric analysis showed a significantly (P , .01) reduced mean percentage of tumor volume following additional further resection after iMRI from 33.5% 6 25.1% to 14.7% 6 23.3% (World Health Organization [WHO] grade I, 32.8% 6 21.9% to 6.1% 6 18.8%; WHO grade II, 24.4% 6 25.1% to 10.8% 6 11.0%; WHO grade III, 35.1% 6 27.3% to 24.8% 6 26.3%; WHO grade IV, 34.2% 6 23.7% to 1.2% 6 16.2%).

CONCLUSION: MRI in conjunction with multimodal navigation and an intraoperative updating procedure enlarges tumor-volume reduction in glioma surgery significantly without higher postoperative morbidity.

Neuro-Oncology DOI:10.1093/neuonc/nor169

Malignant gliomas are the most common and lethal primary intracranial tumors. To date, no reliable biomarkers for the detection and risk stratification of gliomas have been identified. Recently, we demonstrated significant levels of microRNAs (miRNAs) to be present in cerebrospinal fluid (CSF) samples from patients with primary CNS lymphoma. Because of the involvement of miRNA in carcinogenesis, miRNAs in CSF may serve as unique biomarkers for minimally invasive diagnosis of glioma.

The objective of this pilot study was to identify differentially expressed microRNAs in CSF samples from patients with glioma as potential novel glioma biomarkers.

With use of a candidate approach of miRNA quantification by reverse-transcriptase polymerase chain reaction (qRT-PCR), miRNAs with significant levels in CSF samples from patients with gliomas were identified. MiR-15b and miR-21 were differentially expressed in CSF samples from patients with gliomas, compared to control subjects with various neurologic disorders, including patients with primary CNS lymphoma and carcinomatous brain metastases. Receiver- operating characteristic analysis of miR-15b level revealed an area under the curve of 0.96 in discriminating patients with glioma from patients without glioma. Moreover, inclusion of miR-15b and miR-21 in combined expression analyses resulted in an increased diagnostic accuracy with 90% sensitivity and 100% specificity to distinguish patients with glioma from control subjects and patients with primary CNS lymphoma.

In conclusion, the results of this pilot study demonstrate that miR-15b and miR-21 are markers for gliomas, which can be assessed in the CSF by means of qRT-PCR. Accordingly, miRNAs in the CSF have the potential to serve as novel biomarkers for the detection of gliomas.

Neuro-Oncology 13(8):806–819, 2011. doi:10.1093/neuonc/nor054

Neuroimaging enables the noninvasive evaluation of glioma and is considered to be one of the key factors for individualized therapy and patient management, since accurate diagnosis and demarcation of viable tumor tissue is required for treatment planning as well as assessment of treatment response. Conventional imaging techniques like MRI and CT reveal morphological information but are of limited value for the assessment of more specific and reproducible information about biology and activity of the tumor. Molecular imaging with PET is increasingly implemented in neuro-oncology, since it provides additional metabolic information of the tumor, both for patient management as well as for evaluation of newly developed therapeutics.Different molecular processes have been proposed to be useful, like glucose consumption, expression of amino acid transporters, proliferation rate, membrane biosynthesis, and hypoxia. Thus, PET might help neuro-oncologists gain further insights into tumor biology by “true molecular imaging” as well as understand treatment-related phenomena. This review describes the method of PET acquisition as well as the tracers used to image biological processes in gliomas. Furthermore, it considers the clinical impact of PET on the use of currently available radiotracers, which were shown to be potentially valuable for discrimination between neoplastic and nonneoplastic tissue, as well as on tumor grading, determinination of treatment response, and providing an outlook toward further developments.

Neurosurgery 69:194–206, 2011 DOI: 10.1227/NEU.0b013e31821d0e4c

Awake craniotomy with electrocortical mapping and intraoperative magnetic resonance imaging (iMRI) are established techniques for maximizing tumor resection and preserving function, but there has been little experience combining these methodologies.

OBJECTIVE: To report our experience of combining awake craniotomy and iMRI with a 1.5-T movable iMRI for resection of gliomas in close proximity to eloquent cortex.

METHODS: Twelve patients (9 male and 3 female patients; age, 32-60 years; mean, 41 years) undergoing awake craniotomy and iMRI for glioma resections were identified from a prospective database. Assessments were made of how these 2 modalities were integrated and what impact this strategy had on safety, surgical decision making, workflow, operative time, extent of tumor resection, and outcome.

RESULTS: Twelve craniotomies were safely performed in an operating room equipped with a movable 1.5-T iMRI. The extent of resection was limited because of proximity to eloquent areas in 5 cases: language areas in 3 patients and motor areas in 2 patients. Additional tumor was identified and resected after iMRI in 6 patients. Average operating room time was 7.9 hours (range, 5.9-9.7 hours). Compared with preoperative neurological function, immediate postoperative function was stable/improved in 7 and worse in 5; after 30 days, it was stable/improved in 11 and worse in 1.

CONCLUSION: Awake craniotomy and iMRI with a movable high-field-strength device can be performed safely to maximize resection of tumors near eloquent language areas.

J Neurosurg 115:11–17, 2011. DOI: 10.3171/2011.2.JNS101451

Accurate discrimination between tumor and normal tissue is crucial for optimal tumor resection. Qualitative fluorescence of protoporphyrin IX (PpIX), synthesized endogenously following d-aminolevulinic acid (ALA) administration, has been used for this purpose in high-grade glioma (HGG). The authors show that diagnostically significant but visually imperceptible concentrations of PpIX can be quantitatively measured in vivo and used to discriminate normal from neoplastic brain tissue across a range of tumor histologies.

Methods. The authors studied 14 patients with diagnoses of low-grade glioma (LGG), HGG, meningioma, and metastasis under an institutional review board–approved protocol for fluorescence-guided resection. The primary aim of the study was to compare the diagnostic capabilities of a highly sensitive, spectrally resolved quantitative fluorescence approach to conventional fluorescence imaging for detection of neoplastic tissue in vivo.

Results. A significant difference in the quantitative measurements of PpIX concentration occurred in all tumor groups compared with normal brain tissue. Receiver operating characteristic (ROC) curve analysis of PpIX concentration as a diagnostic variable for detection of neoplastic tissue yielded a classification efficiency of 87% (AUC = 0.95, specificity = 92%, sensitivity = 84%) compared with 66% (AUC = 0.73, specificity = 100%, sensitivity = 47%) for conventional fluorescence imaging (p < 0.0001). More than 81% (57 of 70) of the quantitative fluorescence measurements that were below the threshold of the surgeon’s visual perception were classified correctly in an analysis of all tumors.

Conclusions. These findings are clinically profound because they demonstrate that ALA-induced PpIX is a targeting biomarker for a variety of intracranial tumors beyond HGGs. This study is the first to measure quantitative ALA-induced PpIX concentrations in vivo, and the results have broad implications for guidance during resection of intracranial tumors.

Neurosurg Rev (2011) 34:253–264. DOI 10.1007/s10143-011-0320-y

Glioma is the most frequently occurring brain tumor, but the prognosis of patients with gliomas remains poor despite advances in surgery, radiotherapy, and chemotherapy. Therefore, great efforts have been made to develop improved therapeutic strategies.

Cytokines are a heterogeneous group of soluble small polypeptides or glycoproteins that exert pleiotropic and redundant effects that promote the growth, differentiation, and activation of normal cells. Cytokines have either pro- or anti-inflammatory activity and immunosuppressive activity, depending on the microenvironment surrounding the tumor. The microenvironment consists of heterogeneous tumor cells, immune cells, and extracellular matrix.

Modulation of the microenvironment by the tumor is essential for its growth and progress. Cytokine production acts as a means of communication in the tumor microenvironment.

In this article, we review the cross-talk between cytokines in the tumor microenvironment and the cytokine therapies that have been used till date for glioma treatment.

Neurosurgery 68[ONS Suppl 2]:ons282–ons290, 2011. DOI: 10.1227/NEU.0b013e318212464e

The ability to diagnose brain tumors intraoperatively and identify tumor margins during resection could maximize resection and minimize morbidity. Advances in optical imaging enabled production of a handheld intraoperative confocal microscope.

OBJECTIVE: To present a feasibility analysis of the intraoperative confocal microscope for brain tumor resection.

METHODS: Thirty-three patients with brain tumor treated at Barrow Neurological Institute were examined. All patients received an intravenous bolus of sodium fluorescein before confocal imaging with the Optiscan FIVE 1 system probe. Optical biopsies were obtained within each tumor and along the tumor-brain interfaces. Corresponding pathologic specimens were then excised and processed. These data was compared by a neuropathologist to identify the concordance for tumor histology, grade, and margins.

RESULTS: Thirty-one of 33 lesions were tumors (93.9%) and 2 cases were identified as radiation necrosis (6.1%). Of the former, 25 (80.6%) were intra-axial and 6 (19.4%) were extra-axial. Intra-axial tumors were most commonly gliomas and metastases, while all extra-axial tumors were meningiomas. Among high-grade gliomas, vascular neoproliferation, as well as tumor margins, were identifiable using confocal imaging. Meningothelial and fibrous meningiomas were distinct on confocal microcopy—the latter featured spindle-shaped cells distinguishable from adjacent parenchyma. Other tumor histologies correlated well with standard neuropathology tissue preparations.

CONCLUSION: Intraoperative confocal microscopy is a practicable technology for the resection of human brain tumors. Preliminary analysis demonstrates reliability for a variety of lesions in identifying tumor cells and the tumor-brain interface. Further refinement of this technology depends upon the approval of tumor-specific fluorescent contrast agents for human use.

Neurosurg Rev (2010) 33:441–449. DOI 10.1007/s10143-010-0280-7

Randomized phase III trials have shown significant improvement of survival 1, 2, and 3 years after implantation of 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) wafers for patients with newly diagnosed malignant glioma. But these studies and subsequent non-phase III studies have also shown risks associated with local chemotherapy within the central nervous system. The introduction of concomitant radiochemotherapy with temozolomide (TMZ) has later demonstrated a survival benefit in a phase III trial and has become the current treatment standard for newly diagnosed malignant glioma patients. Lately, this has resulted in clinical protocols combining local chemotherapy with BCNU wafers and concomitant radiochemotherapy with TMZ although this may carry the risk of increased toxicity.

We have compiled the treatment experience of seven neurosurgical centers using implantation of carmustine wafers at primary surgery followed by 6 weeks of radiation therapy (59–60 Gy) and 75 mg/m2/day TMZ in patients with newly diagnosed glioblastoma followed by TMZ monochemotherapy. We have retrospectively analyzed the postoperative clinical course, occurrence and severity of adverse events, progression-free interval, and overall survival in 44 patients with newly diagnosed glioblastoma multiforme. All patients received multimodal treatment including tumor resection, BCNU wafer implantation, and concomitant radiochemotherapy. Of 44 patients (mean age 59±10.8 years) with glioblastoma who received Gliadel wafer at primary surgery, 28 patients (64%) had died, 16 patients (36%) were alive, and 15 patients showed no evidence of clinical or radiographic progression after a median follow-up of 15.6 months. At time of analysis of adverse events in this patient population, the median overall survival was 12.7 months and median progression-free survival was 7.0 months. Surgical, neurological, and medical adverse events were analyzed. Twenty-three patients (52%) experienced adverse events of any kind including complications that did not require treatment. Nineteen patients (43%) experienced grade 3 or grade 4 adverse events. Surgical complications included cerebral edema, healing abnormalities, cerebral spinal fluid leakage, meningitis, intracranial abscess, and hydrocephalus. Neurological adverse events included newly diagnosed seizures, alteration of mental status, and new neurological deficits. Medical complications were thromboembolic events (thrombosis, pulmonary embolism) and hematotoxicity.

Combination of both treatment strategies, local chemotherapy with BCNU wafer and concomitant radiochemotherapy, appears attractive in aggressive multimodal treatment schedules and may utilize the sensitizing effect of TMZ and carmustine on MGMT and AGT on their respective drug resistance genes. Our data demonstrate that combination of local chemotherapy and concomitant radiochemotherapy carries a significant risk of toxicity that currently appears underestimated. Adverse events observed in this study appear similar to complication rates published in the phase III trials for BCNU wafer implantation followed by radiation therapy alone, but further add the toxicity of concomitant radiochemotherapy with systemic TMZ. Save use of a combined approach will require specific prevention strategies for multimodal treatments.

J Neurosurg 112:1020–1032, 2010. DOI: 10.3171/2009.7.JNS09758

The aim of this study was to answer the question whether quality of life and progression-free and overall survival are increased in adults with supratentorial malignant glioma who are treated with cytoreductive resection as compared with those who only undergo biopsy.

Methods. A literature search of the electronic databases MEDLINE, EMBASE, and CENTRAL was performed to identify relevant studies published before May 2008. Hand-searching of reference lists of the identified studies and relevant review articles was also performed. A study was considered eligible, regardless of study design (prospective or retrospective), if: 1) quality of life and/or progression-free and/or overall survival was compared among adult patients undergoing biopsy or resection, and 2) patient age and Karnofsky Performance Scale scores were not significantly different among the 2 groups compared.

Results. One randomized controlled trial and 4 retrospective studies (involving a total of 1111 patients) were found eligible for this systematic review. A meta-analysis of the eligible studies demonstrated a significant increase in overall survival in the patients treated with resection instead of biopsy (hazard ratio 0.61, 95% CI 0.52–0.71, p < 0.0001, fixed-effect model). Although statistical pooling was not feasible, the available data suggest that quality of life was increased in patients treated with resection rather than biopsy, while there did not seem to be any significant difference in progression-free survival between the 2 groups.

Conclusions. Based on the best available evidence, it appears that cytoreductive resection in adults with supratentorial malignant glioma is associated with improved overall survival as compared with biopsy. However, well designed prospective studies are needed for more solid conclusions to be drawn.

SPINE Volume 34, Number 22S, pp S69 –S77, 2009

Study Design. Clinically based systematic review.

Objective. To define optimal clinical care for primary intramedullary spinal cord tumors using a systematic re- view with expert opinion.

Methods. Focused questions on the treatment of primary intramedullary spinal cord tumors were refined by a panel of spine oncology surgeons, medical and radiation oncologist. Keyword were searched through Medline database and pertinent abstracts and manuscripts obtained. The quality of literature was rated as high, moderate, low, or very low. Using the GRADE evidence based review system the proposed questions were answered using the literature review and expert opinion. These treatment recommendations were then rated as either strong or weak based on the quality of evidence and clinical expertise.

Results. The literature searches revealed low and very low quality evidence with no prospective or randomized studies. The MEDLINE search engine returned 9000 articles which was restricted to articles about human subjects and written in the English language. The subsequent search resulted in a return of: “spinal cord tumor” (5053), “ependymoma” (580), “astrocytoma” (420), and “glioma” (235) articles. Seventeen articles referenced timing of surgical intervention and symptomatology for intramedullary spinal cord tumors. One hundred fifty-eight chemotherapy and 183 radiation therapy articles for intramedullary spinal cord tumors were reviewed.

Conclusion. The most important factor in determining the IMSCT patient’s long-term neurologic and functional outcome after surgery is the patient’s preoperative neurologic status. However, this must be taken in the context of the underlying tumor histology. Therefore, resection is reserved for progressive neurologic decline and serial monitoring for asymptomatic individuals. Adjuvant therapy is an option for high grade astrocytomas (WHO grades 3–4).

Journal of Clinical Oncology. DOI:10.1200/JCO.2008.19.8721

Purpose

We evaluated the efficacy of bevacizumab (Avastin TM), alone and in combination with irinotecan, in patients with recurrent glioblastoma in a phase II, multicenter, open-label, noncomparative trial.

Patients and Methods

One hundred sixty-seven patients were randomly assigned to receive bevacizumab 10 mg/kg alone or in combination with irinotecan 340 mg/m2 or 125 mg/m2 (with or without concomitant enzyme-inducing antiepileptic drugs, respectively) once every 2 weeks. Primary end points were 6-month progression-free survival and objective response rate, as determined by independent radiology review. Secondary end points included safety and overall survival.

Results

In the bevacizumab-alone and the bevacizumab-plus-irinotecan groups, estimated 6-month progression-free survival rates were 42.6% and 50.3%, respectively; objective response rates were 28.2% and 37.8%, respectively; and median overall survival times were 9.2 months and 8.7 months, respectively. There was a trend for patients who were taking corticosteroids at baseline to take stable or decreasing doses over time. Of the patients treated with bevacizumab alone or bevacizumab plus irinotecan, 46.4% and 65.8%, respectively, experienced grade  3 adverse events, the most common of which were hypertension (8.3%) and convulsion (6.0%) in the bevacizumab-alone group and convulsion (13.9%), neutropenia (8.9%), and fatigue (8.9%) in the bevacizumab-plus-irinotecan group. Intracranial hemorrhage was noted in two patients (2.4%) in the bevacizumab-alone group (grade 1) and in three patients (3.8%) patients in the bevacizumabplus-irinotecan group (grades 1, 2, and 4, respectively).

Conclusion

Bevacizumab, alone or in combination with irinotecan, was well tolerated and active in recurrent glioblastoma.

DOI: 10.3171/2009.7.JNS09758

The aim of this study was to answer the question whether quality of life and progression-free and overall survival are increased in adults with supratentorial malignant glioma who are treated with cytoreductive resection as compared with those who only undergo biopsy.

Methods. A literature search of the electronic databases MEDLINE, EMBASE, and CENTRAL was performed to identify relevant studies published before May 2008. Hand-searching of reference lists of the identified studies and relevant review articles was also performed. A study was considered eligible, regardless of study design (prospective or retrospective), if: 1) quality of life and/or progression-free and/or overall survival was compared among adult patients undergoing biopsy or resection, and 2) patient age and Karnofsky Performance Scale scores were not significantly different among the 2 groups compared.

Results. One randomized controlled trial and 4 retrospective studies (involving a total of 1111 patients) were found eligible for this systematic review. A meta-analysis of the eligible studies demonstrated a significant increase in overall survival in the patients treated with resection instead of biopsy (hazard ratio 0.61, 95% CI 0.52–0.71, p <0.0001, fixed-effect model). Although statistical pooling was not feasible, the available data suggest that quality of life was increased in patients treated with resection rather than biopsy, while there did not seem to be any significant difference in progression-free survival between the 2 groups.

Conclusions. Based on the best available evidence, it appears that cytoreductive resection in adults with supratentorial malignant glioma is associated with improved overall survival as compared with biopsy. However, welldesigned prospective studies are needed for more solid conclusions to be drawn.

Vini G. Khurana, PhD, FRACS, Charles Teo, MBBS, FRACS, Michael Kundi, PhD, Lennart Hardell, MD, PhD, Michael Carlberg, MSc.

Surgical Neurology Volume 72, Issue 3, Pages 205-214 (September 2009) doi:10.1016/j.surneu.2009.01.019

The debate regarding the health effects of low-intensity electromagnetic radiation from sources such as power lines, base stations, and cell phones has recently been reignited. In the present review, the authors attempt to address the following question: is there epidemiologic evidence for an association between long-term cell phone usage and the risk of developing a brain tumor? Included with this meta-analysis of the long-term epidemiologic data are a brief overview of cell phone technology and discussion of laboratory data, biological mechanisms, and brain tumor incidence.

In order to be included in the present meta-analysis, studies were required to have met all of the following criteria: (i) publication in a peer-reviewed journal; (ii) inclusion of participants using cell phones for ≥10 years (ie, minimum 10-year “latency”); and (iii) incorporation of a “laterality” analysis of long-term users (ie, analysis of the side of the brain tumor relative to the side of the head preferred for cell phone usage). This is a meta-analysis incorporating all 11 long-term epidemiologic studies in this field.

The results indicate that using a cell phone for ≥10 years approximately doubles the risk of being diagnosed with a brain tumor on the same (“ipsilateral”) side of the head as that preferred for cell phone use. The data achieve statistical significance for glioma and acoustic neuroma but not for meningioma.

Conclusion

The authors conclude that there is adequate epidemiologic evidence to suggest a link between prolonged cell phone usage and the development of an ipsilateral brain tumor.