Microscope-based Neuronavigation Research Articles

Brain abscess caused by Streptococcus pyogenes with atypical symptoms: a case report and literature review

BackgroundStreptococcus pyogenes is a common gram-positive bacterium, belonging to group A Streptococcus (GAS), and is responsible for causing a range of clinical conditions. Brain abscess caused by GAS is uncommon in pediatric infectious diseases, and GAS brain abscess without acute infectious symptoms has been rarely reported.Case presentationWe present a case of one GAS brain abscess in a previously healthy child with unusual clinical manifestations of decreased muscle strength in the left limbs. The right frontal lobe mass lesion was resected using a microscope-based neuronavigation system. A sole defectively beta-hemolytic Streptococcus pyogenes was isolated from the lesion. The patient’s peripheral blood whole-exome and the pathogen’s whole-genome sequencing were performed respectively, revealing a heterozygous mutation in the interferon regulatory factor-8 (IRF8) gene in the patient and lack of hyaluronic acid capsules in Streptococcus pyogenes (genotype emm22). The patient eventually recovered after prompt surgical drainage of the abscess and appropriate antibiotic treatment.ConclusionsIt is important to pay attention to Streptococcus pyogenes brain abscesses with mild clinical manifestations. Upon reviewing all the cases of pediatric GAS brain abscess reported in the published literature, we discovered that early diagnosis and treatment are crucial factors that impact the prognosis of GAS brain abscess.

Intraoperative high-field MRI maximizes the extent of resection in intraventricular central neurocytoma surgery

Central neurocytoma (CN) is a rare benign neuronal tumor of the ventricular system. Microsurgical resection is considered to be the mainstay of treatment for intraventricular CN, and the extent of resection is the most important prognostic factor. We describe our initial experience in the management of intraventricular CN with intraoperative MRI together with microscope-based neuronavigation. During a 5year period between February 2009 and June 2014, 18 consecutive patients with histologically proven CN were included in this study. Gross total tumor resection was achieved in 88.9% (16/18) of patients. There were no perioperative deaths, and the overall complication rate was 61.1% (11/18). The Karnofsky Performance Status score at the last follow-up was 100 in eight (44.4%), 90 in seven (38.9%), and ⩽70 in three patients (16.7%). We conclude that intraoperative high-field MRI combined with microscope-based neuronavigation can maximize the extent of resection in intraventricular CN surgery and minimize the risks of neurological impairment.

Intraoperative visualization for resection of gliomas: the role of functional neuronavigation and intraoperative 1.5 T MRI

Objective: To investigate how functional neuronavigation and intraoperative high-field magnetic resonance imaging (MRI) influence glioma resection.Methods: One hundred and thirty-seven patients [World Health Organization (WHO) grade I: 20; II: 19; III: 41; IV: 57] underwent resection for supratentorial gliomas in an operative suite equipped with intraoperative high-field MRI and microscope-based neuronavigation. Besides standard anatomical image data including T1- and T2-weighted sequences, various functional data from magnetoencephalography (n=37), functional MRI (n=65), positron emission tomography (n=8), MR spectroscopy (n=28) and diffusion tensor imaging (n=55) were integrated in the navigational setup.Results: Intraoperative MRI showed primary complete resection in 27% of all patients (I: 50%; II: 53%; III: 2%; IV: 28%). In 41% of all patients (I: 40%; II: 26%; III: 66%; IV: 28%) the resection was extended owing to intraoperative MRI increasing the percentage of complete resections to 40% (I: 70%; II: 58%; III: 17%; IV: 40%). Integrated application of functional navigation resulted in low post-operative morbidity with a transient new neurological deficit in 10.2% (paresis: 8.8% and speech disturbance: 1.4%) decreasing to a permanent deficit in 2.9% (four of 137 patients with a new or increased paresis).Conclusions: The combination of intraoperative MRI and functional navigation allows safe extended resections in glioma surgery. However, despite extended resections, still in the majority of the grade III and IV gliomas no gross total resection could be achieved owing to the extension of the tumor into eloquent brain areas. Intraoperative MRI data can be used to localize the tumor remnants reliably and compensate for the effects of brain shift.

Visualization of the pyramidal tract in glioma surgery by integrating diffusion tensor imaging in functional neuronavigation

Object The aim of this study was to investigate whether diffusion tensor imaging (DTI) can be integrated into functional navigation for the intraoperative visualization of the pyramidal tract. Methods A single-shot spin-echo diffusion-weighted echo planar imaging sequence on a 1.5 T magnetic resonance (MR) scanner was used for DTI. One null image and six diffusion-weighted images (high B value 1 000 mm/s2) were obtained. Color-encoded fractional anisotropy maps of the principal eigenvector rendered as a boxoid within each voxel were used for segmentation of the pyramidal tract. The segmented images were rigidly registered with a T1-weighted gradient echo 3D dataset for navigation in 16 patients with gliomas. In tumors adjacent to the motor cortex (n=6) data from functional MR imaging were co-registered. Results The whole DTI processing lasted about 25-30 minutes in each case. In all cases DTI could be integrated into the navigational dataset resulting in an intraoperative visualization of the pyramidal tract by microscope-based navigation. Navigational accuracy measured as the target registration error was 1.2±0.46 mm. Registration of fractional anisotropy maps with the 3D navigational dataset was possible with an error of less than 2 mm. Co-registration with fMRI was consistent with DTI data. A neurological deterioration was observed only in one patient. Conclusions DTI can be reliably integrated into navigational datasets. Thus, microscope-based neuronavigation can be used for an intraoperative visualization of the course of the pyramidal tract. However, a possible shifting of the pyramidal tract has to be taken into account after major tumor parts are removed.

Visualization of the Pyramidal Tract in Glioma Surgery by Integrating Diffusion Tensor Imaging in Functional Neuronavigation

The aim of this study was to investigate whether diffusion tensor imaging (DTI) can be integrated into functional navigation for the intraoperative visualization of the pyramidal tract. A single-shot spin-echo diffusion-weighted echo planar imaging sequence on a 1.5 T magnetic resonance (MR) scanner was used for DTI. One null image and six diffusion-weighted images (high B value 1 000 mm/s (2)) were obtained. Color-encoded fractional anisotropy maps of the principal eigenvector rendered as a boxoid within each voxel were used for segmentation of the pyramidal tract. The segmented images were rigidly registered with a T(1)-weighted gradient echo 3D dataset for navigation in 16 patients with gliomas. In tumors adjacent to the motor cortex (n = 6) data from functional MR imaging were co-registered. The whole DTI processing lasted about 25-30 minutes in each case. In all cases DTI could be integrated into the navigational dataset resulting in an intraoperative visualization of the pyramidal tract by microscope-based navigation. Navigational accuracy measured as the target registration error was 1.2 +/- 0.46 mm. Registration of fractional anisotropy maps with the 3D navigational dataset was possible with an error of less than 2 mm. Co-registration with fMRI was consistent with DTI data. A neurological deterioration was observed only in one patient. DTI can be reliably integrated into navigational datasets. Thus, microscope-based neuronavigation can be used for an intraoperative visualization of the course of the pyramidal tract. However, a possible shifting of the pyramidal tract has to be taken into account after major tumor parts are removed.

Intraoperative high-field-strength MR imaging: implementation and experience in 200 patients.

To review the initial clinical experience with intraoperative high-field-strength magnetic resonance (MR) imaging of brain lesions in 200 patients. Two hundred patients (mean age, 46.1 years; range, 7-84 years), most of whom had glioma or pituitary adenoma, were examined with a 1.5-T MR imager equipped with a rotating operating table and located in a radiofrequency-shielded operating theater. A navigation microscope placed inside the 0.5-mT zone and used in combination with a ceiling-mounted navigation system enabled integrated microscope-based neuronavigation. The extent of resection depicted at intraoperative imaging, the surgical consequences of intraoperative imaging, and the clinical practicability of the operating room setup were analyzed. Seventy-seven resections with a transsphenoidal approach, 100 craniotomies, and 23 burr-hole procedures were performed. In 55 (27.5%) of 200 patients, intraoperative MR imaging had immediate surgical consequences (eg, extension of resection in 39% of patients with pituitary adenoma or glioma). In 108 patients the navigation system was used, and for 37 of those patients, functional imaging data were integrated into the navigation system. There was nearly no difference in quality between pre- and intraoperative images. Intraoperative workflow with intraoperative patient transport for imaging was straightforward, and imaging in most cases began less than 2 minutes after sterile covering of the surgical site. No complications resulted from high-field-strength MR imaging. The high-field-strength MR imager was successfully adapted for intraoperative use with the integrated neuronavigation system. Intraoperative MR imaging provided valuable information that allowed intraoperative modification of the surgical strategy.

Functional neuronavigation—risk grading for surgery in close proximity to eloquent motor cortex

BACKGROUNDTumor removal, brain swelling, the use of brain retractors, and cerebrospinal-fluid drainage all result in an intraoperative brain deformation that is known as brain shift. Thus, neuronavigation systems relying on preoperative image data have a decreasing accuracy during the surgical procedure. Intraoperative image data represent the correct anatomic situation, so their use may compensate for the effects of brain shift.METHODSIn a series of 16 brain tumor patients, we used intraoperative magnetic resonance (MR) imaging to obtain 3-D data, which were then transferred to the microscope-based neuronavigation system. With the help of bone fiducial markers these images were registered intraoperatively, updating the neuronavigation system.RESULTSIn all patients the updating of the neuronavigation system with the intraoperative MR data was successful. It led to reliable neuronavigation with high accuracy; the mean registration error of the update procedure in all patients was 1.1 mm. The updating procedure added about 15 minutes to the operation time. In all patients the area suggestive of remaining tumor was reached and the additional tumor could be resected, resulting in a complete tumor removal in 14 patients. In the remaining patients extension of the tumor into eloquent brain areas prevented a complete excision.CONCLUSIONSThe update of a neuronavigation system with intraoperative MR images reliably compensates for the effects of brain shift. This method allows completion of tumor removal in some difficult brain tumors.

Functional neuronavigation and intraoperative MRI.

Our concept of computer assisted surgery is based on the combination of intraoperative magnetic resonance (MR) imaging with microscope-based neuronavigation, providing anatomical and functional guidance simultaneously. Intraoperative imaging evaluates the extent of a resection, while the additional use of functional neuronavigation, which displays the position of eloquent brain areas in the operative field, prevents increasing neurological deficits, which would otherwise result from extended resections. Up to mid 2001 we performed intraoperative MR imaging using a low-field 0.2 Tesla scanner in 330 patients. The main indications were the evaluation of the extent of resection in gliomas, pituitary tumours, and in epilepsy surgery. Intraoperative MR imaging proved to serve as intraoperative quality control with the possibility of an immediate modification of the surgical strategy, i.e. extension of the resection. Integrated use of functional neuronavigation prevented increased neurological deficits. Compared to routine pre- or postoperative imaging being performed with high-Tesla machines, intraoperative image quality and sequence spectrum could not compete. This led to the development of the concept to adapt a high-field MR scanner to the operating environment, preserving the benefits of using standard microsurgical equipment and microscope-based neuronavigational guidance with integrated functional data, which was successfully implemented by April 2002. Up to the end of 2002, 95 patients were investigated with the new setup. Improved image quality, intraoperative workflow, as well as enhanced sophisticated intraoperative imaging possibilities are the major benefits of the high-field setup.

First clinical results of intraoperative high-field magnetic resonance imaging supported by neuronavigation

A new setup for intraoperative imaging, combining the benefits of high-field magnetic resonance (MR) imaging with microscope-based neuronavigation, providing anatomical and functional guidance was established by adapting a rotating operating table to a 1.5 T MR scanner, placed in a radiofrequency-shielded operating theatre. The navigation microscope placed in the 5 G zone in combination with a ceiling mounted navigation system enables integrated microscope-based neuronavigation. A total of 126 patients, mainly gliomas and pituitary adenomas, were investigated. In 29% of all patients, intraoperative MR imaging resulted in a repeated inspection of the surgical field with a modification of the surgical strategy. In 62 patients, microscope-based navigation was used, in 21 functional data were integrated. Navigational accuracy was not impeded by the magnetic fringe field. Imaging quality was not disturbed by the operating environment; there was hardly a difference in imaging quality between pre- and intraoperative scans. Intraoperative workflow with patient transport for imaging was straightforward. We did not encounter any untoward events due to the high magnetic field. Standard high-field MR scanners can be successfully adapted to an operating environment including integrated neuronavigational support. Their intraoperative application offers increased image quality and a broad spectrum of different imaging modalities, compared to previous low-field systems.

Integration of MR spectroscopy into neuronavigation for stereotactic definition of tumor infiltration zone

BACKGROUNDTumor removal, brain swelling, the use of brain retractors, and cerebrospinal-fluid drainage all result in an intraoperative brain deformation that is known as brain shift. Thus, neuronavigation systems relying on preoperative image data have a decreasing accuracy during the surgical procedure. Intraoperative image data represent the correct anatomic situation, so their use may compensate for the effects of brain shift.METHODSIn a series of 16 brain tumor patients, we used intraoperative magnetic resonance (MR) imaging to obtain 3-D data, which were then transferred to the microscope-based neuronavigation system. With the help of bone fiducial markers these images were registered intraoperatively, updating the neuronavigation system.RESULTSIn all patients the updating of the neuronavigation system with the intraoperative MR data was successful. It led to reliable neuronavigation with high accuracy; the mean registration error of the update procedure in all patients was 1.1 mm. The updating procedure added about 15 minutes to the operation time. In all patients the area suggestive of remaining tumor was reached and the additional tumor could be resected, resulting in a complete tumor removal in 14 patients. In the remaining patients extension of the tumor into eloquent brain areas prevented a complete excision.CONCLUSIONSThe update of a neuronavigation system with intraoperative MR images reliably compensates for the effects of brain shift. This method allows completion of tumor removal in some difficult brain tumors.

Preliminary experience in glioma surgery with intraoperative high-field MRI.

To apply a new setup, combining the benefits of high-field magnetic resonance imaging (MRI) with microscope-based neuronavigation, providing anatomical and functional guidance, in glioma surgery. MR imaging was performed using a 1.5 T scanner, located in a radiofrequency-shielded operating theatre. The patient is lying on a rotating operating table, which is locked at the 160 degree position for surgery at the 5 G zone and turned into the scanner for imaging. The microscope, placed in the 5 G zone, in combination with a ceiling mounted navigation system enables microscope-based neuronavigation; integrated data from magnetoencephalography and functional MRI provide functional guidance. 126 patients were investigated with intraoperative high-field MRI, among them were 37 patients with gliomas. In the biopsy/catheter group (n = 8) MRI reliably depicted the needle position or the location of catheter placement. In the group with glioma resection (n = 29) intraoperative MRI revealed that the surgical objective was not achieved in 28%, leading to further tumour removal. We did not observe complications attributable to intraoperative high-field MRI. Image quality was not diminished by the operating room equipment, so that there was nearly no noticeable difference between pre- and intraoperative image quality. Neuronavigational guidance was applied in 31 patients: the integrated use of functional data prevented an increased morbidity despite extended resections. Intraoperative high-field MRI allows a reliable delineation of the extent of resection in glioma surgery. If the surgical objective was not met, a modification of the surgical strategy during the same operation is possible, thus leading to more radical resections. Furthermore, high-field MRI offers increased image quality and a much broader spectrum of different imaging modalities, compared to previous intraoperative low-field systems.

Model of Surgical Procedures for Multimodal Image-Guided Neurosurgery

Objective: Improvement of the planning stage of image-guided surgery requires a better anticipation of the surgical procedure and its anatomical and functional environment. This anticipation should be provided by acquisition of multimodal medical images of the patient and by a better understanding of surgical procedures. In this paper, we propose improvements to the planning and performance of multimodal image-guided neurosurgery through the use of information models related to neurosurgical procedures.Materials and Methods: A new generic model of surgical procedures is introduced in the context of multimodal image-guided craniotomies. The basic principle of the model is to break down the surgical procedure into a sequence of steps denning the surgical script. In the model, a step is defined by an action. The model assigns to each surgical step a list of image entities extracted from multimodal preoperative images (i.e., anatomical and/or functional images) which are relevant to the performance of that particular step. A semantic validation of the model was performed by instantiating the model entities for 29 surgical procedures.Results: The resulting generic model is described by a UML class diagram and a textual description. The validation showed the relevance of the model, confirming the main underlying assumptions. It also provided some leads to improve the model.Conclusion: While further validation is needed, the initial benefits of this approach can already be outlined. It should add real value to the different levels of image-guided surgery, from preprocessing to planning, as well as during surgery. Models of surgical procedures can manage image data according to the surgical script, which should lead to better anticipation of surgery through the development of simulation tools. Furthermore, the models may improve the performance of surgery using microscope-based neuronavigation systems by making it possible to adapt both visualization and interaction features of multimodal preoperative images according to the model.

Intraoperative compensation for brain shift

BACKGROUND Tumor removal, brain swelling, the use of brain retractors, and cerebrospinal-fluid drainage all result in an intraoperative brain deformation that is known as brain shift. Thus, neuronavigation systems relying on preoperative image data have a decreasing accuracy during the surgical procedure. Intraoperative image data represent the correct anatomic situation, so their use may compensate for the effects of brain shift. METHODS In a series of 16 brain tumor patients, we used intraoperative magnetic resonance (MR) imaging to obtain 3-D data, which were then transferred to the microscope-based neuronavigation system. With the help of bone fiducial markers these images were registered intraoperatively, updating the neuronavigation system. RESULTS In all patients the updating of the neuronavigation system with the intraoperative MR data was successful. It led to reliable neuronavigation with high accuracy; the mean registration error of the update procedure in all patients was 1.1 mm. The updating procedure added about 15 minutes to the operation time. In all patients the area suggestive of remaining tumor was reached and the additional tumor could be resected, resulting in a complete tumor removal in 14 patients. In the remaining patients extension of the tumor into eloquent brain areas prevented a complete excision. CONCLUSIONS The update of a neuronavigation system with intraoperative MR images reliably compensates for the effects of brain shift. This method allows completion of tumor removal in some difficult brain tumors.

An experimental approach to image guided skull base surgery employing a microscope-based neuronavigation system.

A cadaveric study was undertaken to investigate the usefulness and reliability of a microscope based navigation system (NS) for skull base surgery. CT-scans (1 mm slices) were performed in 10 fixed cadaver heads after implantation of fiducials. There upon, various skull base dissections were undertaken: transethmoidal-transsphenoidal approach to sella and clivus, retrosigmoidal approach to the internal auditory canal (IAC) and to the posterior semicircular canal (PSCC). The navigated dissections were performed with the MKM, a microscope based navigation system of Carl Zeiss (Oberkochen, Germany). The registration assessment by the NS yielded a mean deviation of 0.23 mm +/- 0.03 mm (mean +/- SD, n = 7, range 0.19 to 0.27 mm). The real anatomical deviation during dissection was 0.67 mm +/- 0.2 mm for navigation to the IAC and 0.71 mm +/- 0.37 mm to the PSCC. This accuracy was achieved with three fiducials (4 x 1 mm titanium screws) arranged as a triangle (side length 4-6 cm) nearby the surgical field. Navigation data on current position, direction and distance to a target structure were helpful in the transethmoidal-transsphenoidal approach to the clivus, as well as for accessing deep seated structures (C1-C2 junction, petrous bone tip). The contouring feature was beneficial for identifying structures embedded in the bone. However, due to inaccurate 3-D modelling this feature has a restricted reliability. Our cadaveric skull base study has shown that the MKM is a reliable tool with high anatomical accuracy and usefulness of most navigation features. However, in order to effectively and reliably use any NS the surgeon must be familiar with its potential features and limitations as is demonstrated in this study.