Neurosurgical Tumor Resection Research Articles

Mapping of Broca's region using repetitive transcranial magnetic stimulation in correlation to functional and structural imaging

Objective: Broca's area in the left hemisphere is macro-anatomically defined by the pars opercularis and the pars triangularis of the inferior frontal gyrus, represented in cytoarchitectonic Area 44 and Area 45 respectively. Beyond speech production in general, Broca's area is supposed to be linked to differentiated functional roles in language processing. The objective of our study is to combine complementary data from functional and structural-anatomical imaging with the electrophysiological method of transcranial magnetic stimulation (TMS) in order to individually map the Broca's region within the speech network. The background idea is to identify the functionally mandatory proportions of Broca's region which is a prerequisite in neurosurgical tumor resection. In analogy to electrical brain stimulation in awake surgery, the so called “virtual lesion technique” TMS allows for inducing an acute and exhaustive reversible dysfunction without structural damage and thus directly identifies cortical areas involved in language processing. Therefore, it is an elegant method to enable for causative evidence, which vice versa complement imaging data.

Expression of aquaporin 5 and the AQP5 polymorphism A(-1364)C in association with peritumoral brain edema in meningioma patients

Aquaporins (AQP) are a growing family of water-channel proteins, numbering 13 to date. Recent studies have reported AQP1 and AQP4 to be involved in the development and resorption of brain edemas of different origin. Other AQPs have also been detected in brain tissue, but their impact on brain edema remains to be shown. To evaluate a possible role of AQP5 in brain edema, we investigated the association of AQP5 expression and the functional AQP5 promoter polymorphism A(-1364)C with occurrence and intensity of peritumoral edema in meningioma patients. Peritumoral edema was classified in three degrees based on preoperative imaging in 89 meningioma patients treated at the University Hospital Essen between 2003 and 2006. AQP5 expression was assessed immunohistochemically in tumor tissue obtained during neurosurgical tumor resection. Genotypes of the A(-1364)C polymorphism were determined using the "slowdown" polymerase chain reaction. Higher levels of AQP5 expression were significantly correlated with the AQP5-1364 AA genotype (P = 0.02). AQP5 expression was positively correlated with edema (P = 0.04). AQP5 genotypes were not significantly associated with the occurrence, but with the intensity of peritumoral brain edema (P = 0.04). In our cohort, 40 % of patients with grade I, 66.7 % with grade II, and 76.5 % with grade III edema possessed at least one A allele. Development and intensity of peritumoral edema in meningiomas are associated with AQP5 expression. The intensity of edema correlates with the AQP5 A(-1364)C genotype. This suggests AQP5 as an interesting new candidate involved in peritumoral brain edema in meningioma patients.

Meningeome

The prognosis of the generally benign meningiomas is mainly an issue of the likelihood of recurrence, which increases with WHO grade (7-20% in WHO grade I, 29-40% in WHO grade II, and 50-78% in WHO grade III meningiomas). Among clinical parameters the most important prognostic factor is the completeness of neurosurgical tumor resection. Among histopathological prognostic parameters the mitotic activity is the most important one. As the cutoffs of the mitotic index (MI) are defined for each grade by the WHO classification of brain tumors and because the MI can be applied as the sole grading criterion, the reliable and reproducible assessment of the MI is crucial for an appropriate risk stratification. This is provided by immunohistochemical mitosis markers, i.e., phospho-histone H3 (PHH3). The PHH3 method is superior to the conventional mitosis counting method and therefore allows a more reliable risk stratification. The Ki-67 labeling index provides additional prognostic information, especially in prognostically ambiguous meningiomas. Cytogenetically, the deletion of the short arm of one chromosome 1 (1p-) is an unfavorable prognostic parameter and is correlated with a high risk of recurrence. The enzyme reaction for alkaline phosphatase (ALPL) is a fast and efficient screening method, which strongly indicates an intact chromosome 1 in cases with a positive enzyme reaction.

Time‐domain and spectral‐domain optical coherence tomography in the analysis of brain tumor tissue

Detection of residual tumor during resection of glial brain tumors remains a challenge because of a low inherent contrast of adjacent edematous brain, the surrounding infiltration zone, and the solid tumor. Therefore, new technologies that may facilitate an intraoperative analysis of the tissue at the resection edge are of great interest to neurosurgeons. For ex vivo imaging of gliomas in a mouse model and human biopsy specimens of brain tumors and nervous system tissue we have used a time-domain Sirius 713 Tomograph with a central wavelength of 1,310 nm and a coherence length of 15 microm equipped with a mono mode fiber and a modified optical coherence tomography (OCT) adapter containing a lens system for imaging at a working distance of 2.5 cm. A spectral-domain tomograph using 840 nm and 930 nm superluminescence diodes (SLD) with a central wavelength of 900 nm was used as a second imaging modelity. Both time-domain and spectral-domain coherence tomography delineated normal brain, the infiltration zone and solid tumor in murine intracerebral gliomas. Histological evaluation of H&E sections parallel to the optical plain demonstrated that tumor areas of less than a millimeter could be detected and that not only solid tumor, but also brain invaded by a low-density single tumor cells produced an OCT signal different from normal brain. Spectral-domain OCT (SD-OCT) demonstrated a significantly more detailed microstructure of tumor and normal brain up to a tissue depth of 1.5-2.0 mm, whereas the interpretation of time-domain OCT (TD-OCT) was difficult at a tissue depth >1.0 mm. Because of rapid scanning times SD-OCT data could be acquired as 3D data maps, which allowed a multi-planar analysis of the tumor to brain interface. Similar to our findings in experimental gliomas, images of human nervous system tissue acquired using SD-OCT showed a characteristic signal of normal brain tissue and a detailed microstructure of tumor parenchyma. Spectral-domain OCT of experimental gliomas and human brain tumor specimens differentiates solid tumor, diffusely invaded brain tissue, and adjacent normal brain based on microstructure and B-scan signal characteristics. In conjunction with the rapid image acquisition rates of SD-OCT, this technology carries the potential of a novel intraoperative imaging tool for the detection of residual tumor and guidance of neurosurgical tumor resections.

Multimodal anatomic, functional, and metabolic brain imaging for tumor resection

Objective: Improvement of neurosurgical techniques with a more detailed description of brain tumors and their functional environment. Methods: We performed: (1) anatomical magnetic resonance imaging (MRI) for reference, (2) functional sequences dedicated to the adjacent cortical structures (sensorimotor, visual, language paradigms), and (3) thallium 201 cerebral tomoscintigraphy to visualize active tumor invasion. Data were transferred to a workstation for automatic registration. Results: All data were combined into one synthetic image showing the foci of high proliferative activity, which have to be completely resected, and the peritumoral functional structures, which have to be spared in order to minimize postoperative sequelae. This trimodal image is entered into a surgical neuronavigation computer for preoperative planning in order to outline tumoral target and functional risk areas. All this information is displayed in the operative microscope (Zeiss MKM) optically linked to MR images. This multimodality technique diminishes operative time by reducing electrocorticography and improves the operative short-term outcome. Conclusion: Multimodal imaging is useful for optimization of neurosurgical tumor resection.

SPECT-MR Image Fusion in the Intraoperative MR for Guidance of Neurosurgical Tumor Resection

SPECT-MR Image Fusion in the Intraoperative MR for Guidance of Neurosurgical Tumor Resection

SPECT-MR Image Fusion in the Intraoperative MR for Guidance of Neurosurgical Tumor Resection

SPECT-MR Image Fusion in the Intraoperative MR for Guidance of Neurosurgical Tumor Resection

Expression of calcitonin gene-related peptide 1 receptor mRNA in human trigeminal ganglia and cerebral arteries

Reverse transcriptase polymerase chain reaction (RT-PCR) using primers for the recently cloned human CGRP 1 receptor detected mRNA expression of CGRP 1 receptors in trigeminal ganglia and cerebral vessels, obtained at autopsy or during neurosurgical tumor resections. An RT-PCR product of the expected size (339 bp) was seen in cerebral arteries, both in the presence and in the absence of endothelium and in trigeminal ganglia. Sequence analysis of the RT-PCR product of the published sequence showed 100% homology with the human CGRP 1 receptor. The presence of the CGRP 1 receptor mRNA in human trigeminal ganglia and cerebral blood vessels, indicates the occurrence of both prejunctional (trigeminal) and postjunctional location (blood vessels) of the CGRP 1 receptor.