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PubMed2006

[Treatment of chronic tinnitus with neuronavigated repetitive Transcranial Magnetic Stimulation (rTMS)].

BACKGROUND AND OBJECTIVE: Idiopathic tinnitus is a frequent and debilitating disorder of largely unknown pathophysiology. Focal brain activation in the auditory cortex has recently been demonstrated in chronic tinnitus. Low-frequency rTMS can reduce cortical hyperexcitability. PATIENTS AND METHODS: In 12 patients with chronic tinnitus, fusion of [18F]deoxyglucose-PET and structural MRI (T1, MPRAGE) scans allowed the area of increased metabolic activity in the auditory cortex to be exactly identified; this area was selected as the target for rTMS. A neuronavigational system adapted for TMS positioning enabled the relative positions of the figure-8 coil and the target area to be monitored. Repetitive TMS (110% motor threshold; 1 Hz; 2000 stimuli per day over 5 days) was performed using a placebo-controlled crossover design. A sham coil system was used for the placebo stimulation. Treatment outcome was assessed with a specific tinnitus questionnaire (Goebel and Hiller). RESULTS: In all 12 patients an asymmetrically increased metabolic activation of the gyrus of Heschl was detected. The tinnitus score was significantly improved after 5 days of active rTMS, an effect not seen after placebo stimulation. CONCLUSION: These preliminary results show that neuronavigated rTMS may improve our understanding and treatment of chronic tinnitus.

Adult↗
PubMed2006

Classical and real-time neuronavigation in pediatric neurosurgery.

INTRODUCTION: Neuronavigation has become a cornerstone of neurosurgery. Navigation systems are categorized into two main groups: those based on preoperative imaging and those based on real-time intraoperative acquired images. OBJECTIVES: The preoperative imaging systems, either computed tomography (CT)- or magnetic resonance imaging (MRI)-based, are straight-forward systems that are routinely used in most institutions. Image accuracy, however, decreases secondary to brain and lesion shifts that occur during surgery. Intraoperative, real-time navigation systems overcome anatomical shifts by updating the image base of the navigation during surgery, thus, maintaining precise navigation capabilities throughout the surgical procedure. CONCLUSIONS: In this article, we review the main neuronavigation systems and their applications, emphasizing their unique advantages and usage within the pediatric population.

Adolescent↗
PubMed2005

Brain tumour surgery in the vicinity of short-term memory representation--results of neuronavigation using fMRI images.

OBJECTIVE: Functional information concerning the surrounding brain is mandatory for a good clinical outcome in brain tumour surgery. The value of fMRI to detect the motorcortex and Broca's area is widely accepted today. If an appropriate paradigm is used, short-term memory areas can be visualized as well. Obviously this information must be integrated into cranial neuronavigation for an appropriate intra-operative use. We report our first experiences with the direct integration of short-term memory fMRI into cranial neuronavigation. METHOD: From January 2001 to March 2002 14 patients were operated on for intracranial tumours with short-term memory fMRI imaging, using the "two-back-paradigm". Both pre- and postoperatively, the short-term memory of all patients was tested additionally by a standardized test battery including 16 different verbal and visuo-spatial items. RESULTS: In all 14 patients the general level of working memory capacity was preserved after surgery. The visuo-spatial performance was kept unchanged or deteriorated slightly, the alertness slightly worsened as well, but we found an improvement in verbal test items. CONCLUSION: The two-back paradigm is able to visualize verbal memory tasks in fMRI. For visuo-spatial items, a new paradigm has to be designed. In contrast to deep seated brain lesions, focal cortical impairments do not lead to obvious and serious memory deficits. Therefore, the aim of gross total tumour removal has to be balanced against the aim of preservation of short-term memory fields. Nevertheless, the knowledge of the localization of cortical short-term memory fields may combine both aims during navigated brain tumour surgery, thus preserving the patient with a better quality of life.

Adult↗
PubMed2003

Combining MEG and MRI with neuronavigation for treatment of an epileptiform spike focus in the precentral region: a technical case report.

BACKGROUND: Epileptic foci are often located in the vicinity but not necessarily within the boundaries of intra-axial brain tumors. Resection of these tumors is based on two major goals: first, maximizing tumor removal without provoking new neurologic deficits, and second, minimizing epileptic seizure activity. Magnetic source imaging (MSI) depicts the generators of magnetic fields overlaid on individual magnetic resonance (MR) images. Established application areas are lesions located adjacent to or partly within the sensory and motor cortex, or in the depth of the brain, necessitating a surgical approach through functionally highly relevant cortical regions. Magnetoencephalography (MEG) is also applicable for epileptiform spike foci recording during interictal activity. CASE DESCRIPTION: A patient with a recurrent glioma close to the Rolandic cortex scheduled for epilepsy and tumor surgery was investigated with MSI. The MSI data showed an epileptiform spike focus outside the tumor boundaries. The resulting MSI images were integrated into our neuronavigation system. This procedure allowed for the preoperative identification of the sensory and motor cortex, the precise localization of the epileptiform spike focus, and careful planning of the surgical procedure. In this case, we were able to safely resect the recurrent tumor and the epileptiform spike focus under general anesthesia using MSI-based neuronavigational guidance but no conventional intraoperative mapping techniques. CONCLUSION: Magnetic source imaging can be a valuable, noninvasive method for planning and performing tumor resections in high-risk brain regions, especially if an epileptiform spike focus has to be localized and included into the resection strategy.

Brain Neoplasms↗
PubMed2003

Technical refinements for validating functional MRI-based neuronavigation data by electrical stimulation during cortical language mapping.

Preoperative functional neuroimaging techniques represent an appealing method to localize language areas in tumor surgery, but their reliability still needs to be confirmed by accurate comparison with more invasive but validated mapping techniques like intraoperative electrical cortical stimulation. Two patients harboring a glioma involving speech areas underwent mapping of language function by preoperative functional magnetic resonance imaging (fMRI), whose results were integrated into the neuronavigation device, and by intraoperative electrical stimulation mapping (ESM). The utilization of neuronavigation allowed us to estimate the degree of spatial correspondence between language areas detected by the two techniques. Language areas identified by functional magnetic resonance imaging on the cerebral cortex exposed during surgery corresponded to those identified by invasive mapping in both patients. It was possible to achieve a gross total tumor removal while respecting language areas in both cases, with no permanent postoperative phasic aggravation. The concordance of results between pre- and intraoperative mapping techniques in our patients indicates that preoperative fMRI language mapping may prove useful when planning the resection of intracerebral lesions in language areas. However, accurate neurofunctional imaging protocols and image analysis are crucial to obtain a preoperative language mapping that is in agreement with ESM findings.

Brain Mapping↗
PubMed2006

Endoscopy guided by an intraoperative 3D ultrasound-based neuronavigation system.

OBJECTIVE: We have investigated the feasibility of using 3D ultrasound-based neuronavigation for guiding neuroendoscopy. METHODS: A neuronavigation system with an integrated ultrasound scanner was used for acquiring the 3D ultrasound image data. The endoscope with a tracking frame attached was calibrated to the navigation system. The endoscope was guided based on intraoperative 3D ultrasound data in 9 operations. In 5 of the operations, ultrasound angiography data were also obtained. Updated image data (e. g., more than one 3D ultrasound dataset) were obtained in 6 of the operations. RESULTS: We found that the image quality of 3D ultrasound was sufficient for image guidance of the endoscope. Planning of the entry point and trajectory as well as finding optimal sites for fenestration were successfully performed. Blood vessels were visualized by 3D ultrasound angiography. In one procedure of third ventriculostomy, the basilar artery was visualized. Updated image data were quickly obtained, and in two of the cases, a reduction of the size of cysts was demonstrated. CONCLUSIONS: 3D ultrasound gives accurate images of sufficiently high quality for image guidance of neuroendoscopy. Updated 3D ultrasound datasets can easily be acquired and may adjust for brain shift. Ultrasound angiography image data are also available with this technology and can visualize vessels of importance.

Adult↗
PubMed2003

Neuronavigation accuracy dependence on CT and MR imaging parameters: a phantom-based study.

Clinical benefits from neuronavigation are well established. However, the complexity of its technical environment requires a careful evaluation of different types of errors. In this work, a detailed phantom study which investigates the accuracy in a neuronavigation procedure is presented. The dependence on many different imaging parameters, such as field of view, slice thickness and different kind of sequences (sequential and spiral for CT, T1-weighted and T2-weighted for MRI), is quantified. Moreover, data based on CT images are compared to those based on MR images, taking into account MRI distortion. Finally, the contributions to global accuracy coming from image acquisition, registration and navigation itself are discussed. Results demonstrate the importance of imaging accuracy. Procedures based on CT proved to be more accurate than procedures based on MRI. In the former, values from 2 to 2.5 mm are obtained for 95% fractiles of cumulative distribution of Euclidean distances between the intended target and the reached one while, in the latter, the measured values range from 3 to 4 mm. The absence of imaging distortion proved to be crucial for registration accuracy in MR-based procedures.

Algorithms↗
PubMed2003

Neuronavigated rTMS in a patient with chronic tinnitus. Effects of 4 weeks treatment.

Clinical, neurophysiological and neuroimaging data suggest that chronic tinnitus resembles neuropsychiatric syndromes characterised by focal brain activation. Low frequency repetitive transcranial magnetic stimulation (rTMS) has been proposed as an efficient method in treating brain hyperexcitability disorders. In one patient suffering from chronic tinnitus, [18F]deoxyglucose PET revealed increased metabolic activity in a circumscript area of the left primary auditory cortex (PAC). The effect of MRI and PET guided neuronavigated 1 Hz rTMS of this area was evaluated in a single-blind, sham-controlled, cross-over manner, followed by a 4-week open treatment. Following active stimulation there was a remarkable effect, enduring several weeks, on tinnitus sensation, which was paralleled by altered cortical excitability. These findings suggest that neuronavigated rTMS of increased PAC activity might offer a new option for treating auditory phantom perceptions like chronic tinnitus.

Chronic Disease↗
PubMed2001

Clinical experiences in neuronavigation.

We have successfully used a navigation system in more than 120 neurosurgical operations for past two years. The neuronavigation system provides high levels of mechanical accuracy in surgical localization, especially for small deep-seated masses or epileptic foci, surgical planning for intrinsic and extrinsic brain tumors, and arteriovenous malformation and guidance of instrumentation of spinal surgery. The ages of the patients were from 12 months to 75 years. The sex distribution was equal. Computed tomography or magnetic resonance imaging with 2-3 mm thick slices were employed for image guidance. The clinical experiences included 50 cases of deep-seated mass, 50 cases of surgical planning for tumor or vascular mass excision and 20 cases of spinal instrumentation treatment. There were no mechanical failures. Neuronavigation definitely provides a good technology in frameless brain and spinal surgeries.

Brain Neoplasms↗
PubMed2006

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.

Adolescent↗
PubMed2006

Neuronavigation-assisted transoral-transpharyngeal approach for basilar invagination--two case reports.

Two patients presented with congenital basilar invagination manifesting as progressive myelopathy. Both patients underwent surgery using a neuronavigation-assisted transoral-transpharyngeal approach. The Brain-LAB Vector Vision navigation system was used for image guidance. The registration accuracies were 0.9 and 1.3 mm. After decompression, posterior stabilization was performed. Both patients had an uneventful postoperative course. The transoral-transpharyngeal approach with the neuronavigation system provides safe exposure and decompression for basilar invagination.

Adult↗
PubMed2003

Multimodal image fusion in ultrasound-based neuronavigation: improving overview and interpretation by integrating preoperative MRI with intraoperative 3D ultrasound.

OBJECTIVE: We have investigated alternative ways to integrate intraoperative 3D ultrasound images and preoperative MR images in the same 3D scene for visualizing brain shift and improving overview and interpretation in ultrasound-based neuronavigation. MATERIALS AND METHODS: A Multi-Modal Volume Visualizer (MMVV) was developed that can read data exported from the SonoWand neuronavigation system and reconstruct the spatial relationship between the volumes available at any given time during an operation, thus enabling the exploration of new ways to fuse pre- and intraoperative data for planning, guidance and therapy control. In addition, the mismatch between MRI volumes registered to the patient and intraoperative ultrasound acquired from the dura was qualified. RESULTS: The results show that image fusion of intraoperative ultrasound images in combination with preoperative MRI will make perception of available information easier by providing updated (real-time) image information and an extended overview of the operating field during surgery. This approach will assess the degree of anatomical changes during surgery and give the surgeon an understanding of how identical structures are imaged using the different imaging modalities. The present study showed that in 50% of the cases there were indications of brain shift even before the surgical procedure had started. CONCLUSIONS: We believe that image fusion between intraoperative 3D ultrasound and preoperative MRI might improve the quality of the surgical procedure and hence also improve the patient outcome.

Brain↗
PubMed2005

Characterizing magnetic spike sources by using magnetoencephalography-guided neuronavigation in epilepsy surgery in pediatric patients.

OBJECT: The authors sought to validate magnetoencephalography spike sources (MEGSSs) in neuronavigation during epilepsy surgery in pediatric patients. METHODS: The distributions of MEGSSs in 16 children were defined and classified as clusters (Class I), greater than or equal to 20 MEGSSs with 1 cm or less between MEGSSs; small clusters (Class II), 6 to 19 with 1 cm or less between; and scatters (Class III), less than 6 or greater than 1 cm between spike sources. Using neuronavigation, the MEGSSs were correlated to epileptic zones from intra- and extraoperative electrocorticography (ECoG), surgical procedures, disease entities, and seizure outcomes. Thirteen patients underwent MEGSSs: nine had clusters; two had small clusters, one with and one without clusters; and three had scatters alone. All 13 had scatters. Clusters localized within and extended from areas of cortical dysplasia and at margins of tumors or cystic lesions. All clusters were colocalized to ECoG-defined epileptic zones. Four of 10 patients with clusters and/or small clusters underwent complete excisions, and six underwent partial excision with or without multiple subpial transections. In the three patients with scatters alone, ECoG revealed epileptic zones buried within MEGSS areas; these regions of scatters were completely excised and treated with multiple subpial transections. Coexisting scatters were left untreated in nine of 10 patients. Postoperatively, nine of 13 patients were seizure free; the four patients with residual seizures had clusters in unresected eloquent cortex. Three patients in whom no MEGSSs were demonstrated underwent lesionectomies and were seizure free. CONCLUSIONS: Magnetoencephalography spike source clusters indicate an epileptic zone requiring complete excision. Coexisting scatters remote from clusters are nonepileptogenic and do not require excision. Scatters alone, however, should be examined by ECoG; an epileptic zone may exist within these distributions.

Adolescent↗
PubMed2002

[Neuronavigator-guided microsurgery for resection of brain tumors].

OBJECTIVE: To study locating accuracy for the brain tumors and their peri-structures by the neuronavigator and elucidate the microsurgical effects. METHODS: 65 patients with intracranial tumors were microsurgically treated by the application of Stealth Station and Vector Vision system. The treatment effects were summarized and the neuronavigational accuracy was discussed. RESULTS: After mean fiducial error (MFE) and sustained accuracy (SA) were satisfied. Total tumor removal was achieved in 63 cases (97.0%), subtotal removal in 2 cases (3.0%). The neurological functions were improved in 56 cases (86.2%), unchanged obviously in 9 cases (13.8%). No case deteriorated and died in the group. CONCLUSIONS: Navigation systems are reliable and accurate in making microneurosurgical plans for brain tumors. And they can provide tracing of the tumor in the operation and guide the operator's manipulation. The techniques, which help total removal of the tumors and reduce the postoperative complications, are very useful in guarantee operation effects.

Adult↗
PubMed2004

[Application of computer-assistant neuronavigation in spinal operation].

OBJECTIVE: To discuss the efficacy, accuracy, and safety of computer-assistant neuronavigation in operation of vertebrae and spinal cord. METHODS: The data of computer-assistant neuronavigation used in the operation for 41 cases, including 9 cases of neurinoma, 10 cases of ependymoma, 5 cases of angioreticuloma, 7 cases of spinal meningioma, 4 cases of astrocytoma, and 1 case of cysticercosis, and 1 case of osteoblastoma. from March 2001 to December 2003 were reviewed. RESULTS: Twenty-six screws were fixed in 4 patients. Total removal was succeeded in 33 of the 37 cases of 37 spinal tumors and all patients survived after operation. CONCLUSION: Image-guided navigation for spinal surgery is able to save time and reduce operational lesion. More importantly, it improves neurosurgeon's comprehension of spinal anatomy.

Adolescent↗
PubMed2001

[Neuronavigation-assisted resection of gliomas near eloquent regions].

OBJECTIVE: To evaluate the effect of the neuronavigation system in operation of gliomas near eloquent regions. METHOD: The brain LAB VV2 navigation system was used in 11 patients with gliomas near eloquent regions. The value of this system for glioma resection was assessed, and the accuracy and notice for application were discussed. RESULTS: The mean registration error was (1.5 +/- 0.7) mm in the patients. Total lesion removal was achieved in 9 patients (81.8%). The clinical status of all patients improved, and their functions of motor were not significantly affected. No complications were attributed to the use of this system. CONCLUSION: The neuronavigation system is reliable and accurate in surgical treatment of gliomas near eloquent regions. It increases the fraction of radical in glioma resection without injury to the critical functions.

Adolescent↗
PubMed2002

[Use of magnetoencephalography and functional neuronavigation in planning and surgery of brain tumors].

The role of magnetoencephalography (MEG) in neurology has been established for basic research, epilepsy, and functional brain mapping. The presurgical localization of functionally important brain areas has evolved as an important application of MEG. Both neurologists and neurosurgeons can use this method for decision-making and planning of nonsurgical or surgical treatment in brain tumors. The integration of functional brain mapping data into neuronavigation systems may help to minimize postoperative morbidity. This is especially important in low-grade gliomas, in which a potential benefit of surgery is only achieved when the tumor has been resected completely, whereas neurological deterioration means a substantial loss of quality of life during the survival time. This report addresses the utility of MEG combined with neuronavigation in the treatment of brain tumors adjacent to eloquent brain areas.

Adolescent↗
PubMed2002

Virtual endoscopy combined with intraoperative neuronavigation for planning of endoscopic surgery in patients with occlusive hydrocephalus and intracranial cysts.

We assessed the clinical value of MR ventriculoscopy (virtual endoscopy, VE) combined with image-guided frameless stereotaxy for endoscopic surgery of occlusive hydrocephalus and intracranial cysts. VE was obtained in 20 patients with hydrocephalus and three with intracranial cysts. All surgical operations were endoscopic. The path of the rigid endoscope to the target point was planned using neuronavigation. VE was carried out along the same trajectory retrospectively in 20 cases and prospectively in three. The results were analysed for demonstration of anatomical landmarks and structures at risk. VE was successful in all patients. Possible obstacles to endoscopic access to the lamina terminalis and the basal cisterns and structures at risk, such as the basilar artery, were clearly shown in relation to the direction of the endoscope. However, the floor of the third ventricle and septum pellucidum were not clearly seen and possible abnormalities could therefore not be appreciated. VE can provide realistic simulation of endoscopic third ventriculostomy and cystostomy. The appropriate trepanation point and trajectory of the endoscope can be assessed with regard to the size of the foramen of Monro and the position of vulnerable structures. This simulated trajectory can be adapted to the field of operation by image-guided neuronavigation. This regime may potentially reduce the risk of damage to intracranial structures.

Adolescent↗