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At least 235 records · Page 13Linked to original sources

PubMed2003

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

OBJECTIVE: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Adolescent↗

PubMed2002

Low-field magnetic resonance imaging for intraoperative use in neurosurgery: a 5-year experience.

The aim of this study was to evaluate the feasibility and point out the indications of intraoperative MR imaging in neurosurgical procedures. The MR imaging was performed using a 0.2-T scanner which was located in a radiofrequency-shielded operating theater. Three major setups for intraoperative imaging were possible: inside the scanner; at the 5-Gauss line; or in an adjacent operating theater. Additionally, in lesions adjacent to eloquent brain areas microscope- and pointer-based neuronavigation with integrated functional data was applied. Three hundred ten patients were investigated in the previous 5 years, among them gliomas ( n=95), pituitary tumors ( n=81), and 39 non-lesional cases in whom resective or disconnective epilepsy surgery was carried out. We did not observe any adverse effects due to intraoperative MR imaging. Image quality was sufficient to evaluate the extent of the tumor resection in the majority of cases. The main indications for intraoperative MR imaging were the evaluation of the extent of a resection in glioma, ventricular tumor, pituitary tumor, and in epilepsy surgery. Intraoperative MR imaging offers the possibility of further tumor removal during the same surgical procedure in case of tumor remnants, increasing the rate of complete tumor removal. Furthermore, the effects of brain shift, which would lead to inaccurate neuronavigation, can be compensated for by an update of the neuronavigation system with intraoperative MR image data.

Adult↗

PubMed2003

Image guided surgery for petrous apex lesions.

OBJECTIVES: To evaluate whether computer-assisted frameless stereotactic navigation in the temporal bone provides sufficient clinical application accuracy and thus a useful tool in temporal bone surgery. METHODS: Two patients with petrous apex cholesterol granuloma were operated on by an epidural middle fossa approach using a Stealth/Medtronic trade mark neuronavigation system. Based on literature data optimal skin fiducial placement and registration methods were used. Intra-operative accuracy was checked using three precise anatomical landmarks. Drilling of the petrous apex bone was guided by neuronavigation. Postoperative Computed Tomography (CT) images were fused with the preoperative CT and planning. RESULTS: The application of image-guidance in temporal bone surgery causes no additional burden to the patient nor prolongs the operating time. The accuracy measured at the anatomical landmarks was under 2,0 mm. This is confirmed by evaluation of bone removal through image fusion of pre- and postoperative CT-scan. CONCLUSIONS: The clinical application of a neuronavigation system during petrous apex surgery can be regarded as useful. Using all available data on registration methods it seems possible to obtain intra-operative application accuracies of <2,0 mm. Additional cadaver work is being performed to support these data.

Adult↗

PubMed2003

Stereoscopic navigation-controlled display of preoperative MRI and intraoperative 3D ultrasound in planning and guidance of neurosurgery: new technology for minimally invasive image-guided surgery approaches.

OBJECTIVE: This paper demonstrates a method that brings together three essential technologies for surgery planning and guidance: neuronavigation systems, 3D visualization techniques and intraoperative 3D imaging technologies. We demonstrate the practical use of an in-house interactive stereoscopic visualization module that is integrated with a 3D ultrasound based neuronavigation system. MATERIALS AND METHODS: A stereoscopy volume visualization module has been integrated with a 3D ultrasound based neuronavigation system, which also can read preoperative MR and CT data. The various stereoscopic display modalities, such as "cut plane visualization" and "interactive stereoscopic tool guidance" are controlled by a pointer, a surgical tool or an ultrasound probe. Interactive stereoscopy was tested in clinical feasibility case studies for planning and guidance of surgery procedures. RESULTS: By orientating the stereoscopic projections in accordance to the position of the patient on the operating table, it is easier to interpret complex 3D anatomy and to directly take advantage of this 3D information for planning and surgical guidance. In the clinical case studies, we experienced that the probe-controlled cut plane visualization was promising during tumor resection. By combining 2D and 3D display, interpretation of both detailed and geometric information may be achieved simultaneously. The possibilities of interactively guiding tools in a stereoscopic scene seemed to be a promising functionality for use during vascular surgery, due to specific location of certain vessels. CONCLUSION: Interactive stereoscopic visualization improves perception and enhances the ability to understand complex 3D anatomy. The practical benefit of 3D display is increased considerably when integrated with surgical navigation systems, since the orientation of the stereoscopic projection corresponds to the orientation of the patient on the operating table. Stereoscopic visualizations work well on MR and CT images, although volume rendering techniques are especially suitable for intraoperative 3D ultrasound image data.

Brain Neoplasms↗

PubMed2004

Cavernous malformations--navigational supported surgery.

OBJECTIVE: Navigational supported surgery of intracranial lesions is expected to be associated with a lower rate of brain traumatization as well as an avoidance of additional neurological deficits and surgical morbidity. In our study we used the computer-assisted image guidance for resection of cerebral cavernous malformations. METHODS: In all patients the planning procedure for the following image-guided surgery was realized using preoperative MRl data sets and a neuronavigation system (STP 4.0, SNN). In cases in which the cavernoma was situated near functional eloquent regions, functional MR images were fused preoperatively. RESULTS: During the last 24 months, 21 patients were surgically treated for cerebral cavernoma. No patient was operated twice. The mean size of cavernoma was 18.3 mm, ranging from 5 to 60 mm, the mean distance between cortical surface and cavernoma was 26 mm, ranging from 5 to 50 mm. The surgical procedure lasted in the median 180 min. All patients showed an identical or better neurological outcome. CONCLUSIONS: Neuronavigation allows an accurate definition of the intraoperative target, a correct approach and a safe surgery. With the help of neuronavigation the surgical approach and the extirpation of cavernous malformations were realized in a comfortable and safe way and allowed a minimization of tissue manipulation.

Adolescent↗

PubMed2004

Combined minimal invasive techniques in deep supratentorial intracerebral haematomas.

Minimal invasive techniques (MIT) like microscopy, stereotaxy, endoscopy and neuronavigation facilitate and improve neurosurgical results and reduce the operative trauma. We report the combined employment of these techniques and the results obtained in our department during the last 7 years in 95 consecutive patients with supratentorial deep located intracerebral haematomas (ICHs). Thirty-six deteriorating patients with deep ICHs under 30 cm (3) volume associated to intraventricular bleeding, were treated early (first 24 hours after bleeding) with neuronavigation guided stereotactic lysis, using multiplanar targets (1 to 3). Microsurgical clot aspiration through an enlarged burr-hole was frequently combined with endoscope- or neuronavigation-assisted evacuation within the first 6 hours after bleeding for the rest of the deteriorating patients with ICHs larger than 30 cm (3). A 1.2 cm narrow surgical corridor assured the least injury to vital cortical areas, tracts and blood vessels. In 86 cases the clots were adequately removed (non-measurable rest) with a reduced morbid mortality (13.8 and 8.6 as well as 23.3 and 16.9 for stereotactic and microscopic MIT, respectively). In our experience, the use of combined MIT adapted to the surgical urgency of the individual patient reduces the operative trauma and improves the accuracy for the access to the clot allowing an adequate haematoma evacuation and a satisfactory outcome in most of the cases.

Adult↗

PubMed2002

Image-guided endoscopic transnasal removal of recurrent pituitary adenomas.

OBJECTIVE: To assess the role that neuronavigation plays in assisting endoscopic transsphenoidal reoperations for recurrent pituitary adenomas. METHODS: During a 45-month period, 19 endoscopic endonasal transsphenoidal reoperations were performed for recurrent pituitary adenomas. In 11 of 19 patients, the procedure was performed with the aid of an optically guided system. Clinical records were reviewed retrospectively, with attention to the following: comparison of baseline clinical data, the duration of surgery, and the postoperative course and complications of both image-guided and non-image-guided endoscopic reoperations. In addition, to test the reliability of the neuronavigation system, we made measurements of intraoperative accuracy in five additional transnasal endoscopic procedures in "virgin" noses and sphenoidal sinuses. RESULTS: In both groups studied, we found no difference with regard to either morbidity or mortality, which were null. The mean setup time was 13 minutes shorter in non-image-guided procedures (P = 0.021), and the operative time was 36 minutes shorter in image-guided procedures (P = 0.038). No other statistically significant differences were found between the two groups. In all cases, we found that the system performed without malfunction. Continuous information regarding instrument location and trajectory was provided to the surgeon. Measurements of the intraoperative accuracy in the axial, coronal, and sagittal planes indicated a mean intraoperatively verified system error of 1.6 +/- 0.6 mm. CONCLUSION: Neuronavigation can be applied during endonasal transsphenoidal endoscopic surgery and requires a minimal amount of time. It makes reoperation easier, faster, and probably safer.

Adenoma↗

PubMed2003

Navigated transoral approach to the cranial base and the craniocervical junction: technical note.

OBJECTIVE: The transoral approach is an elegant reliable surgical procedure that provides anterior exposure of the cranial base and the craniocervical junction. Our objective was to demonstrate the advantages of neuronavigation in planning and performing the transoral approach. METHODS: Three patients with chordomas and one patient with rheumatoid atlantoaxial subluxation were considered for a neuronavigated transoral procedure. For image guidance, the Stryker navigation system (Stryker Instruments, Kalamazoo, MI) was used. Registration was performed with individually constructed occlusal splints with four markers. RESULTS: The transoral approach was successfully used for two patients with chordomas involving the cranial base and the upper spine and for one patient with dislocation of the dens and medullary compression. In one case, preoperative simulation of the approach and trajectory planning demonstrated that adequate resection could not be achieved via the transoral route, and a paracondylar suboccipital approach was used. The registration accuracy achieved with the occlusal splint was less than 1 mm. CONCLUSION: Neuronavigation is a useful tool for planning and performing a transoral approach. It optimizes preoperative planning, clarifies and secures resection limits, and reduces overall surgical morbidity. Registration with an occlusal splint with four markers proved to be an attractive alternative to conventional systems.

Adult↗

PubMed2004

Magnetic resonance angiography image guidance for the microsurgical clipping of intracranial aneurysms: a report of two cases.

To describe the integration of magnetic resonance angiography (MRA) in neuronavigation procedures for microsurgery of intracranial aneurysms. MRA was combined with standard magnetic resonance image (MRI) acquisition in the image-guided planning for the microsurgical clipping of a saccular aneurysm in two patients (one 3-mm large middle cerebral artery and one 8-mm large pericallosal artery aneurysm, diagnosed by catheter angiography in both patients) using two different neurosurgical navigation systems. Conventional 3-D T1-weighted MRI with gadolinium and MRA pulse sequences were acquired in frameless stereotactic conditions the day before surgery and thereafter registered, allowing the definition a minimally invasive straight trajectory to the aneurysm neck. MRA-guided neurosurgery allowed a direct approach to the aneurysms at their proper location, reducing the invasiveness of the approach by tailoring the bone opening and reducing the duration and extension of brain retraction. The technique also avoided unnecessary dissection and exposure of the main trunks and collateral vessels. The aneurysms were successfully eradicated without complication. Integration of MRA in the planning and neuronavigation procedure for intracranial aneurysms may minimize the morbidity related to the surgical approach. This technique may be applicable more routinely using standard neuronavigation equipment.

Adult↗

PubMed2005

Functional monitoring for visual pathway using real-time visual evoked potentials and optic-radiation tractography.

OBJECTIVE: It has been difficult to obtain anatomic and functional information about the visual pathway during neurosurgical operations. The aim of this study was to combine the information of the visual evoked potentials (VEPs) and the anatomic navigation of the optic radiation by diffusion tensor imaging-based tractography for functional monitoring of the visual pathway. METHODS: The subjects were two patients with brain lesions adjacent to the visual pathway. Diffusion tensor imaging-based tractography of the optic radiation was performed by selecting appropriate regions of interest and by fractional anisotropy. During surgery, cortical VEPs were recorded continuously under general anesthesia with sevoflurane. In Patient 2, the results of optic radiation tractography were imported to a neuronavigation system to better understand the spatial relationships between the lesions and the visual pathway (functional neuronavigation). RESULTS: In Patient 1, the lesion did not seem to be attached to the optic radiation, and VEP profiles remained stable during resection. In Patient 2, who had a lesion adjacent to the posterior horn of the lateral ventricle, VEPs suddenly diminished when resection reached the optic radiation as illustrated on the neuronavigation system. As a result, complete left hemianopia developed after surgery in Patient 2. CONCLUSION: We confirmed functional correlations of the results of diffusion tensor imaging-based tractography by monitoring intraoperative VEPs. The combination of continuous VEP and optic-radiation tractography is reliable to monitor the visual function and is helpful in performing neurosurgical planning near the visual pathway.

Adult↗

PubMed2006

A novel platform for image-guided ultrasound.

OBJECTIVE: The combination of classic neuronavigation and intraoperative ultrasound is a recent innovation in image guidance technology. However, this technique requires two hardware components (neuronavigation and an ultrasound system). It was the aim of the study to describe a new simplified technology of a so-called one-platform navigation system developed by our institution in collaboration with the industry and to demonstrate its range of various applications. METHODS: An ultrasound device (IGSonic; BrainLAB, Munich, Germany) is integrated into the VectorVision2 navigation system (BrainLAB, Munich, Germany). The IGSonic Probe 10V5 is connected to the VectorVision Navigation station via an IGSonic Device Box. Once the ultrasound probe is calibrated, the navigated ultrasound displays the sonographic image of the intracranial anatomy on the navigation screen in a composed overlay fashion. It might depict vascular structures within the ultrasound plane by a duplex mode. Ultrasound can also be operated independently from navigation. RESULTS: The VectorVision2 system combines intraoperative ultrasound data sets with preoperatively acquired neuronavigation data sets in plug and play fashion. The system provides a cost-effective intraoperative imaging modality that offers a good anatomic orientation by various composite images, including the display of the amount of brain shift. In our institution, the comprehensible interface led to a routine use of the technology by several neurosurgeons who had not been familiar with the ultrasound technology before. CONCLUSION: The integration of an ultrasound device into an existing navigation system has been successfully developed. The system offers a friendly user interface and cost-effective intraoperative imaging feedback. Although brain shift can be visualized by an image overlay technology as demonstrated by the present system, future developments should aim at fusion techniques of both intra- and preoperative image data sets.

Brain↗

PubMed2001

The Zeiss-MKM system for frameless image-guided approach in epidural motor cortex stimulation for central neuropathic pain.

OBJECT: Twelve patients (seven female, and five male, mean age 55.6 years) suffering from refractory central (ischemic/traumatic [eight cases]) and neuropathic pain (trigeminal neuropathy [four cases]) underwent surgery for the implantation of an epidural motor cortex stimulation (MCS) device in which the authors used a frameless neuronavigation system, the Zeiss-MKM microscope. METHODS: The authors assessed the spatial accuracy of the neuronavigation system and its potential contribution to improve the quality of targeting pain. In these patients, the positions of the central sulcus, defined by stereotactic magnetic resonance MR imaging, intraoperative somatosensory evoked potentials (SSEPs) and subdural visual verification, were correlated into the stereotactic neuronavigation planning procedure. The mean spatial accuracy of distance between (MR) imaging-defined and actual central sulcus was 2.4 mm (range 5-10 mm). The intraoperative SSEPdefined central sulcus was close to that defined by MR imaging (mean distance 6.4 mm). Although very precise, intraoperative SSEP recordings were impaired by artifacts and wave attenuation in six of the 12 patients. Stereotactic correlations between anatomical and functional data in the navigation system corrected final targeting in 10 of 12 cases. Pain relief was obtained in eight patients. Indeed, inappropriate targeting probably explains the reported variable success rate of MCS and certainly underestimates the actual efficacy. CONCLUSIONS: Since intraoperative SSEP monitoring has, for many years, been considered the standard procedure to approach motor target, the development of an accurate stereotactic image guidance system could help to increase the efficacy of MCS on the alleviation of pain. The excellent spatial accuracy provided by the Zeiss-MKM navigation system allows precise data correlations that represent a remarkable means to validate functional MR imaging as an alternative to SSEP. The authors believe that developing stereotactic image guidance with such a navigation system could improve the success rate of MCS.

Deep Brain Stimulation↗

PubMed2001

In vivo experiences with frameless stereotactically guided screw placement in the spine--results from 75 consecutive cases.

Whereas cranial neuronavigation is widely accepted as a helpful tool, larger series of the in vivo application of spinal neuronavigation do not exist. In the following we report our 4-year experience with spinal navigation in 75 consecutive cases for dorsal transpedicular screw placement. Seventy-five patients were planned for operation employing anatomical reference points defined on a 2-mm high resolution CT. We used single vertebra registration and surface matching. With the above methods, the mean registration deviation ranged from 0.18 mm (cervical spine) to 0.31 mm (lumbar spine). All our screws in the upper cervical spine were navigated correctly (17 patients), thus improving markedly the surgical outcome. The results were not as promising in the lumbar area. In only 84% was navigation reliable. The reason was the lack of a practicable tracking tool. Spinal neuronavigation based on anatomical reference points is able to improve the results in transpedicular screwing, especially in the cervical spine. The lack of a practicable tracking tool still hinders its use in routine clinical application.

Bone Screws↗

PubMed2004

Implementation of T2*-weighted MR for multimodal image guidance in cerebral cavernomas.

The aim of this study was to evaluate the feasibility, the safety, and the usefulness of T2*-weighted magnetic resonance (MR) for neuronavigational guidance in patients with cerebral cavernomas. Eight patients with intracerebral cavernomas were operated assisted by T2*-weighted MR image-guidance. The cavernomas were either deep-seated or in eloquent regions. Image fusion of a contrast-enhanced T1-weighted gradient-echo (GRE) sequence with a T2*-weighted GRE sequence was performed via an automated fusion software (StealthMerge). The T2*-weighted images were used to secure complete resection of the cavernoma in all patients and to verify resection of surrounding hemosiderin-stained tissue in epilepsy cases. Furthermore, the multimodal neuronavigational concept included ultrasonography, corticography, and evoked potentials. Postoperative MR excluded any residual malformation in all cases. There was no postoperative morbidity; all epilepsy patients are seizure-free up to now. In our preliminary series, T2*-GRE-guided neuronavigation proved useful for resection control in cavernoma surgery, and we suppose that it will be helpful to clarify the discussion on the value of resection of the surrounding hemosiderin-stained tissue.

Adolescent↗

PubMed2006

Fibers from the dorsal premotor cortex elicit motor-evoked potential in a cortical dysplasia.

OBJECTIVE: To identify the fibers originating from the dorsal premotor cortex (dorsal PMC) that contribute to motor-evoked potentials (MEP), we have applied integrated functional neuronavigation and awake surgery during removal of an epileptic cortical dysplasia located in the right premotor cortex. METHODS: Chronic subdural electrodes were employed for functional mapping during a routine invasive evaluation for intractable epilepsy. After the fibers originating from the dorsal PMC were plotted into the tractography-integrated functional neuronavigation, subcortical MEPs and clinical symptoms were examined during resection of the epileptogenic dorsal PMC. RESULTS: During removal of the epileptogenic area, MEPs were elicited by electrical stimulation of the fibers originating from the dorsal PMC, which were separated from the pyramidal tracts from the precentral gyrus. Resection of the dorsal PMC and its fibers caused a transient dysmetric movement of the left toe without motor weakness. CONCLUSION: Functional corticospinal tract fibers originating from the dorsal PMC can be defined and removed safely under local anesthesia with the aid of integration of functional neuronavigation and subcortical electrical stimulation.

Adolescent↗

PubMed2006

[New surgical techniques for brain tumors].

During the past years, the development of new technologies and techniques has been applied to brain tumor surgery, leading to decreased surgical morbidity and increased efficiency. These techniques can be used to reduce the invasiveness of the surgical approach (endoscopy, neuronavigation, robotics), to improve guidance (stereotaxy, neuronavigation), to better identify the tumor limits (neuronavigation, metabolic imaging, intra-operative MRI) or the functional areas (functional imaging, electrophysiological functional mapping) to optimize resection and to respect eloquent areas. This article reviews these techniques, focusing on their respective principles, practical utility, impact and limits.

Brain Neoplasms↗

PubMed2000

Advanced image-guided skull base surgery.

BACKGROUND: Tumors of the skull base frequently encase or extend into normal neural and vascular structures. Preoperative planning and intraoperative identification of anatomic landmarks is especially important in complex tumors since it helps avoid or minimize surgical morbidity. METHODS: By creating a surgical plan the image guidance software offers help in the establishment of a surgical approach. During surgery, the neuronavigation system displays the location of anatomic landmarks of the skull base regardless of any erosion or displacement. RESULTS: A series of 10 patients with complex tumors in various skull base locations is reported. Osseous structures are easily identified using the CT-based image guidance since these landmarks do not shift due to CSF loss. Image fusion of CT and MRI data gives additional information on the displacement of soft tissue structures. Image fusion in a substraction mode is helpful when a tumor has invaded bony structures or when the encasement of major vessels has to be visualized. CONCLUSION: The preoperative data preparation (planning of the approach, image fusion) plays a vital role in modern neuronavigation and contributes useful information during surgery for complex skull base tumors. Such advanced neuronavigation increases the efficacy and safety of intraoperative maneuvers. Eroded and distorted anatomic landmarks are not subject to a significant amount of intraoperative shift throughout the surgical procedure.

Adult↗

PubMed2002

Preoperative assessment of motor cortex and pyramidal tracts in central cavernoma employing functional and diffusion-weighted magnetic resonance imaging.

BACKGROUND: Functional MRI (fMRI) combines anatomic with functional information and has therefore been widely used for preoperative planning of patients with mass lesions affecting functionally important brain regions. However, the courses of functionally important fiber tracts are not visualized. We therefore propose to combine fMRI with diffusion-weighted MRI (DWI) that allows visualization of large fiber tracts and to implement this data in a neuronavigation system. METHODS: DWI was successfully performed at a field strength of 1.5 Tesla, employing a spin-echo sequence with gradient sensitivity in six noncollinear directions to visualize the course of the pyramidal tracts, and was combined with echo-planar T2* fMRI during a hand motor task in a patient with central cavernoma. RESULTS: Fusion of both data sets allowed visualization of the displacement of both the primary sensorimotor area (M1) and its large descending fiber tracts. Intraoperatively, these data were used to aid in neuronavigation. Confirmation was obtained by intraoperative electrical stimulation. Postoperative MRI revealed an undisrupted pyramidal tract in the neurologically intact patient. CONCLUSION: The combination of fMRI with DWI allows for assessment of functionally important cortical areas and additional visualization of large fiber tracts. Information about the orientation of fiber tracts in normal appearing white matter in patients with tumors within the cortical motor system cannot be obtained by other functional or conventional imaging methods and is vital for reducing operative morbidity as the information about functional cortex. This technique might, therefore, have the prospect of guiding neurosurgical interventions, especially when linked to a neuronavigation system.

Adult↗