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PubMed1997

[Image-guided surgery for epilepsy].

Availability of a neuronavigation system for epilepsy surgery was reported, and its practical use was discussed. Four of nine patients with intractable epilepsy underwent surgical procedures using a neuronavigation system, Viewing wand, from November 1995 to August 1996, in our hospital. The ages of patients were between 9 to 46 years old. Three of them had temporal lobe epilepsy and one had generalized tonic seizures. One of the temporal lobe epilepsy cases had focal cortical dysplasia in the left posterior temporal lobe, and the other one showed that left hippocampal atrophy on MR images. The remaining two patient had no abnormality on MR images. All patients underwent video-EEG monitoring and habitual seizures were recorded at least three times. Ictal and/or interictal SPECT and neuropsychological testing were also performed. Electrocorticograms were recorded intraoperatively in all patients. Surgical procedures using the neuronavigation system were anterior temporal lobectomy, corpus callosotomy and lesionectomy of focal cortical dysplasia. A patient with temporal lobe epilepsy underwent implantation of depth electrodes under the neuronavigation. In temporal lobectomy, image-guided surgery helped to make a decision concerning the safely-resectable size of the lateral temporal cortex and hippocampus. The hippocampus was resected with minimum surgical damage and it made possible a complete histopathological examination. In corpus callosotomy, although it was not easy to confirm the length of the callosal section, the neuronavigation system enabled this to be done quickly. The real-time navigation showed the accurate operating position on three-dimensional images. The location of focal cortical dysplasia was often difficult to identify macroscopically. However, the location of the lesion can be projected to the skin surface under the neuronavigation system. The width of skin incision and craniotomy was able to be made smaller, and the surgery was able to be performed less invasively. The Viewing Wand system was accurate, reliable and easy to operate in these procedures. The navigating error was 2-5 mm. Using CT image data of 5 mm thickness the error was greater, although use of MR image data of 2 mm thickness resulted in relatively small error up to 2-3 mm. The first major factor of the error was the fiducial registration of the patient's head. While the registration was made more strictly with multiple fiducial points, the error was smaller. The second factor was movement of patient's head and/or the navigation arm. The arm and the head should be fixed tightly to the operating table, and it is better if they are fixed together with a supporting arm. The third factor was intraoperative brain shift caused by flow out of the cerebrospinal fluid or removal of mass lesions. This type of error is common in all navigation systems. However, it may be avoided making some real-time feedback system. With the Viewing Wand system, repetition of the intraoperative registration using intracranial anatomical structures reduces this type of error. On the other hand, there were some difficulties on stereotaxic procedures, such as implantation of depth electrodes, using the Viewing Wand. The error was larger than that recorded in other frame-based stereotaxic apparatus. This problem may be improved by a supporting system to fix the probe position. As a neuronavigation system can be widely applied to neurosurgical procedures, we consider that epilepsy and skull-base surgery are the best targets for it because of the minimum possible brain shift. We hope that accurate and less-invasive surgery using a neuronavigation system will contribute to a better outcome for epilepsy patients.

Adolescent↗

PubMed2005

Intraoperative landmarking of vascular anatomy by integration of duplex and Doppler ultrasonography in image-guided surgery. Technical note.

BACKGROUND: The integration of ultrasound technology into neuronavigation systems has recently been the subject of reports by several groups. This article describes our preliminary findings with regard to the integration of data derived from intraoperative duplex (color mode) and Doppler ultrasonography into a neuronavigational data set. It was the aim of the study to investigate (1) whether the intraoperative landmarking of vessels that are outlined with ultrasound technology is possible and (2) whether such a technique might be of clinical interest for neurosurgical interventions. METHODS: The video image of an ultrasound plane (Toshiba, Powervision 6000 SSA-370A, Tokyo, Japan) was integrated into our neuronavigation system (VectorVision2, BrainLab, Heimstetten, Germany). For calibration of the ultrasound plane, an instrument adapter was fixed to the ultrasound probe and then calibrated using a special, predefined calibration phantom. RESULTS: Accordingly, the system supported a combination of the ultrasound plane functionality with the preoperatively acquired neuronavigational data. The duplex and Doppler mode of the ultrasound system displayed the intraoperative vascular anatomy. Once a vessel was outlined during surgery, it could be landmarked by touching the navigation screen. These landmarks were integrated automatically into the neuronavigational data set and could be used to provide intraoperative image updates of the vascular anatomy. This technique was successful in 45 of 47 (95.7%) surgical interventions. CONCLUSIONS: Both image-guided ultrasound and duplex-guided integration of vascular anatomy into the neuronavigational data set are technically possible. In the future, this technology may provide useful intraoperative information during surgery of complex cerebral pathologies.

Blood Vessels↗

PubMed2006

Surgery of cavernous malformations with and without navigational support--a comparative study.

BACKGROUND: The aim of this descriptive study was the comparison of the clinical and surgical data of patients who suffered from cavernoma and were treated surgically with and without intraoperative navigation (ultrasound, neuronavigation). METHOD: Between 1995 and 2002, 40 patients were treated for cavernous malformations microsurgically: 24 patients (group I) using a neuronavigation system (STP 4.0, SNN, Germany), 7 patients (group II) using ultrasound (Siemens Omnia with 5.0 MHz Probe) and 9 patients (group III) without any image guidance using anatomic landmarks. FINDINGS: With the use of neuronavigation the mean sizes of cavernous malformations, which were resected, were reduced from 25.6 mm (group III) and 24.4 mm (group II) to 16.3 mm (group I) (p > or = 0.05). Corresponding to the reduction of the cavernoma size, the mean distances of the vascular lesion to the cortical surface increased from 13.9 mm (group III) and 17.8 mm (group II) to 24.4 mm under neuronavigational support (p > or = 0.05). All cavernomas were resected completely in all 40 patients. Postoperative neuroradiological control (MRI) confirmed complete resection in all cases. No significant differences in the clinical outcome could be evaluated in all three groups up to three months postoperatively. CONCLUSIONS: Use of neuronavigation was associated with a more comfortable and safer surgery of smaller and more deeper-seated cavernomas. In spite of the lack of significance between all groups, the advantages of neuronavigation in planning and realising surgery could be documented, which justify the additional costs and time-consuming acquisition of planning image data and postprocessing as well as intraoperative navigation.

Adolescent↗

PubMed1998

[Intraoperative magnetic resonance tomography for control of extent of neurosurgical operations].

PURPOSE: The main aim of our study was to find out whether the combined use of neuronavigation and intraoperative MRI can increase the rate of "complete tumor removal". The second aim was to characterize the different forms of surgically induced enhancement in order to differentiate them from residual tumor. MATERIALS AND METHODS: Surgery was performed in 18 patients with high-grade glioma. Using a neuronavigation device, the surgeons operated up to the point where they would otherwise have terminated surgery. Intraoperative MRI was then performed to determine whether residual enhancing had been left behind and to update the neuronavigation device. If necessary, feasible surgery was continued. On days 1-3 after surgery early postoperative MRI (1.5 T) was performed. The proportion of patients in whom the enhancing tumor was completely removed was compared with a series of 60 patients with glioblastoma multiforme, who had been operated on using neither neuronavigation nor intraoperative MRI. We also looked for and characterized different types of surgically induced enhancement. RESULTS: Intraoperative MRI definitely showed residual tumor in 6 of the 18 patients and resulted in ambiguous findings in 3 patients. In 7 patients surgery was continued. Early postoperative MRI showed residual tumor in 3 patients and resulted in uncertain findings in 2 patients. The rate of patients in whom complete removal of enhancing tumor could be achieved was 50% at the time of the intraoperative MR examination and 72% at the time of the early postoperative MR control. The difference in proportion of patients with "complete tumor removal" between the groups who had been operated on using neuronavigation (NN) and intraoperative MRI (ioMRI) and those who had been operated on using only modern neurosurgical techniques except NN and ioMRI was statistically highly significant (Fisher exact test; P = 0.008). Four different types of surgically induced contrast enhancement were observed. These phenomena carry different confounding potentials with residual tumor. CONCLUSION: Our preliminary experience with intraoperative MRI in patients with enhancing intraaxial tumors is encouraging. Combined use of neuronavigation and intraoperative MRI was able to increase the proportion of patients in whom complete removal of the enhancing parts of the tumor was achieved. Surgically induced enhancement requires careful analysis of the intraoperative MRI in order not to confuse it with residual tumor.

Astrocytoma↗

PubMed2001

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.

Adolescent↗

PubMed2001

Frameless navigation and endoscopy.

OBJECT: Frameless computerized neuronavigation has been increasingly used in intracranial endoscopic neurosurgery. However, clear indications for the application of neuronavigation in neuroendoscopy have not yet been defined. The purpose of this study was to determine in which intracranial neuroendoscopic procedures frameless neuronavigation is necessary and really beneficial compared with a free-hand endoscopic approach. METHODS: A frameless infrared-based computerized neuronavi- gation system was used in 44 patients who underwent intracranial endoscopic procedures, including 13 third ventriculostomies, nine aqueductoplasties. eight intraventricular tumor biopsy procedures or resections, six cystocisternostomies in arachnoid cysts, five colloid cyst removals, four septostomies in multiloculated hydrocephalus, four cystoventriculostomies in intraparenchymal cysts, two aqueductal stent placements, and fenestration of one pineal cyst and one cavum veli interpositi. All interventions were successfully accomplished. In all procedures, the navigational system guided the surgeons precisely to the target. Navigational tracking was helpful in entering small ventricles, in approaching the posterior third ventricle when the foramen of Monro was narrow, and in selecting the best approach to colloid cysts. Neuronavigation was essential in some cystic lesions lacking clear landmarks, such as intraparenchymal cysts or multiloculated hydrocephalus. Neuronavigation was not necessary in standard third ventriculostomies, tumor biopsy procedures, and large sylvian arachnoid cysts, or for approaching the posterior third ventricle when the foramen of Monro was enlarged. CONCLUSIONS: Frameless neuronavigation has proven to be accurate, reliable, and extremely useful in selected intracranial neuroendoscopic procedures. Image-guided neuroendoscopy improved the accuracy of the endoscopic approach and minimized brain trauma.

Biopsy↗

PubMed2005

Benefits and limitations of image guidance in the surgical treatment of intracranial dural arteriovenous fistulas.

BACKGROUND: Despite major advances in endovascular embolization techniques, microsurgical resection remains a reliable and effective treatment modality for dural arteriovenous fistulas (DAVF). However, intraoperative detection of these lesions and identification of feeding arteries and draining veins can be challenging. In a series of 6 patients who were not candidates for definitive treatment by endovascular embolization we evaluated the benefits and limitations of computer-assisted image guidance for surgical ablation of DAVF. METHODS: Of the 6 patients, 5 presented with haemorrhage and one with seizures. Diagnosis of DAVF was made by conventional angiography and dynamic contrast enhanced MR angiography (CE-MRA). All patients were surgically treated with the assistance of a 3D high resolution T1-weighted MR data set and time-of-flight MR angiography (MRA) obtained for neuronavigation. Registration was based on cranial fiducials and image-guided surgery was performed with the navigation system. FINDINGS: Four of the 6 patients suffered from DAVF draining into the superior sagittal sinus, one fistula drained into paracavernous veins adjacent to the superior petrosal sinus and one patient had a pial fistula draining in the straight sinus. DAVF diagnosed with conventional angiography could be located on CE-MRA and MRA prior to surgery. MRI and MRA images were combined on the neuronavigation workstation and DAVF were located intraoperatively by using a tracking device. In 4 out of 6 cases neuronavigation was used for direct intraoperative identification of DAVF. Brain shift prevented direct tracking of pathological vessels in the other 2 cases, where navigation could only be used to assist craniotomy. Microsurgical dissection and coagulation of the fistulas led to complete cure in all patients as confirmed by angiography. CONCLUSIONS: Neuronavigation may be used as an additional tool for microsurgical treatment of DAVF. However, in this small series of 6 cases, surgical procedures have not been substantially altered by the use of the neuronavigation system. Image guidance has been beneficial for the location of small, superficially located DAVF, whereas a navigated approach to deep-seated lesions was less accurate due to the familiar problem of brain shift and brain retraction during surgery.

Adult↗

PubMed2006

Intraoperative navigated 3-dimensional ultrasound angiography in tumor surgery.

BACKGROUND: Avoiding damage to blood vessels is often the concern of the neurosurgeon during tumor surgery. Using angiographic image data in neuronavigation may be useful in cases where vascular anatomy is of special interest. Since 2003, we have routinely used 3D ultrasound angiography in tumor surgery, and between January 2003 and May 2005, 62 patients with different tumors have been operated using intraoperative 3D ultrasound angiography in neuronavigation. METHODS: An ultrasound-based neuronavigation system was used. In addition to 3D ultrasound tissue image data, 3D ultrasound angiography (power Doppler) image data were acquired at different stages of the operation. The value and role of navigated 3D ultrasound angiography as judged by the surgeon were recorded. RESULTS: We found that intraoperative ultrasound angiography was easy to acquire and interpret, and that image quality was sufficient for neuronavigation. In 26 of 62 cases, ultrasound angiography was found to be helpful by visualizing hidden vessels adjacent to and inside the tumor, facilitating tailored approaches and safe biopsy sampling. CONCLUSIONS: Intraoperative 3D ultrasound angiography is straightforward to use, image quality is sufficient for image guidance, and it adds valuable information about hidden vessels, increasing safety and facilitating tailored approaches. Furthermore, with updated 3D ultrasound angiography imaging, accuracy of neuronavigation may be maintained in cases of brain shift.

Biopsy↗

PubMed2005

Image-guided microneurosurgical management of small cerebral arteriovenous malformations: the value of navigated computed tomographic angiography.

In small arteriovenous malformations (AVM) with large hematomas, surgery remains the main therapeutic option. However, intraoperative identification of the AVM, feeders, and draining veins could be difficult in the environment of substantial intracerebral blood. In those selected cases, we use navigated computed tomographic angiography (CTA) for the microneurosurgical management. It is our objective to report our initial experiences. Prior to operation a conventional CTA with superficial skin fiducials placed on a patient's head was acquired for diagnostic and neuronavigation purposes. Image data were transferred to a neuronavigation device with integrated volume rendering capacities which allows a three-dimensional reconstruction of the vascular tree and the AVM to be created. In all patients the AVM was removed successfully after having been localized with CTA-based neuronavigation. Navigated CTA is helpful for the operative management of small AVMs with large hematomas. The technique allows feeding arteries to be distinguished from draining veins thereby allowing the nidus of the AVM to be identified despite the presence of substantial intracerebral blood. CTA can be easily implemented into commercial neuronavigation systems.

Adult↗

PubMed2002

Versatile intraoperative MRI in neurosurgery and radiology.

BACKGROUND: Several models for the application of intra-operative magnetic resonance imaging (IMRI) have recently been reported, most of them unique. Two fundamental issues need to be addressed: optimal use of the scanner to ensure a wide base for research, development and clinical application, and an organisational model that facilitates such use. METHOD: While in our setting the IMRI project was initiated by the neurosurgeons, the need for wider use of the facilities was recognised since the beginning of the planning phase in 1996. An organisational model was developed that allowed for development of neurosurgical applications, radiological imaging, and radiological interventions and for the research and development work of the vendor. A resistive 0.23 T MR scanner was installed in a dedicated operating room environment. Unique to this scanner is the ability to turn off the magnet, allowing for normal OR activities and devices, and to turn on the magnet as needed with a relatively short six-minute ramp up time. A staged surgical technique was perfected, allowing for transfer of data to the neuronavigator outside the scanner during surgery. In neurosurgery, IMRI was used as one part of a neuronavigational system that included ultrasound imaging, intra-operative cortical stimulation during awake procedures, electrocorticography and two neuronavigators. FINDINGS: 34 neurosurgical cases included 27 brain tumour resections, 5 brain tumour biopsies, 1 extirpation of an arterio-venous malformation, and 1 haematoma evacuation. The scanner could also be used for normal clinical imaging where obese patients, children, claustophobic patients and postoperative control examinations were the major groups. The radiologists performed 110 interventions, including bone and abdominal biopsies, nerve root infiltrations and local pain therapies, with the optical needle tracking system under continuous MRI guidance. The organisational model allowed frequent use of the facilities for both neurosurgery and radiology and continuous development of the facilities. Intra-operative ultrasound was used in 20 tumour resections and in two open brain biopsies. This resulted in reduction of the number of MR imaging sessions during surgery. Five of the 27 resections were performed as awake craniotomies with cortical stimulation. For two of the resections, electrocorticography and depth electrode registrations were used. Furthermore, various non-MRI-compatible instruments and devices were used. INTERPRETATION: Intra-operative MRI is an imaging tool that can be useful especially in the context of neuronavigation. A scanner that can be turned off during surgery is particularly appropriate for neurosurgery. The concept of joint use of such facilities with other clinicians is mutually worthwhile.

Adult↗

PubMed2000

Is the head position during preoperative image data acquisition essential for the accuracy of navigated brain tumor surgery?

OBJECTIVE: To analyze the influence of head positioning during preoperative image data acquisition on intraoperative accuracy of modern neuronavigation systems. MATERIAL AND METHODS: All measurements were performed preoperatively before opening the head. In 24 patients, preoperative MR image data acquisition was performed twice on a 0.5 T scanner using a contrast-enhanced T1-weighted sequence; first in the neutral head position, and thereafter in the surgical head position for pterional craniotomy. For both data sets, the Sylvian fissure, the central sulcus, and the superior and inferior temporal sulci were depicted on the patient's scalp using the frameless neuronavigation system EasyGuide Neurotrade mark. At the beginning of surgery, with the head fixed in a Mayfield clamp and an articulated instrument holder being used for fixation of the navigation system's pointer, the distances of 10 correlating points of the sulci for the two data sets were measured. To evaluate the accuracy of the navigation system in this experimental set-up, a phantom study was also performed. RESULTS: The phantom study revealed a mean inaccuracy of 1.6 mm (range 0.1-2.3 mm, standard deviation 0.6 mm). The patient study revealed a mean inaccuracy of 1.8 mm (range 0.4-2.8 mm, standard deviation 0.5 mm). CONCLUSIONS: The data suggest that the positioning of the patient's head during preoperative imaging plays no relevant role in intraoperative accuracy of neuronavigation. However, further studies and a larger number of patients with various pathologies in different regions of the brain are necessary to obtain a better understanding of the problem of brain shift in neuronavigation due to patient positioning alone, and to avoid procedure-related operative morbidity.

Adult↗

PubMed2000

[Neuro-navigation in the central area: impact on different surgical steps related to the location and various pathological processes].

The neurosurgical treatment of space occupying processes in the central area bears a relatively high risk of either postoperative neurological deficits ("radical approach") or of residual tumor ("conservative approach"). Therefore, special techniques of intraoperative topographic orientation (image-guided surgery) play an important role here. The possible impact of neuronavigation on different neurosurgical steps (craniotomy, corticotomy, localization of the process, definition of borders of resection) was studied in relation to the site of pathology (extraaxial, intraaxial/superficial, intraaxial/deep) in 46 patients harbouring space occupying lesions of the central area. In intraaxial pathologies, additional electrophysiological monitoring was done. It could be shown, that in cases of deep seated processes, neuronavigation had the greatest impact on craniotomy, corticotomy and localization of the process, whereas the borders of resection were defined predominantly on the basis of differences in colour or consistency. In extraaxial pathologies, neuronavigation was of significance only for craniotomy; in intraaxial processes visible at the surface, it had an impact on craniotomy and--in a few cases--on definition of resection borders. In neurosurgery of intraaxial pathologies of the central area (particularly those not visible at the surface), the use of neuronavigation (or another method of intraoperative localization) in combination with neurophysiologic monitoring is strongly recommended.

Aged↗

PubMed2006

Integration of intraoperative 3D-ultrasound in a commercial navigation system.

STUDY AIMS: The purpose of this study was the integration of three-dimensional ultrasound data into a neuronavigation system, in order to allow a guided intraoperative resection control during neurosurgical interventions. MATERIAL AND METHODS: A system for iterative neuronavigation based on 3D-ultrasound (US) has been developed. The main components of the system are the ultrasound device Voluson 730 (GE Healthcare) with a 5 - 9 MHz probe, the navigation system VectorVision2 (BrainLAB AG) and a standard PC with Windows XP. The ultrasound data are transferred via DICOM from the ultrasound device to an external computer, where they are processed with a C++ program for representation in the neuronavigation coordinate system. The data transfer between the navigation system and the external computer is performed via the VVLink interface from BrainLAB. The feasibility test of the system was performed with an ultrasound phantom RMI 403GS (Gammex-RMI GmbH). RESULTS: The error of homologous points mapping from US datasets to a CT dataset in the neuronavigation system was determined to be 1.9 +/- 0.97 mm. The maximum time required to technically integrate the ultrasound data into the navigation system was 1.5 min. CONCLUSIONS: The developed system allows 3D-ultrasound based navigation to be carried out with a commercially available navigation system. The functionality of this system has been proven by technical tests. Recording and integration of the ultrasound data can be repeated at any time during surgery and can be used to update anatomical data and consequently for resection control. Another application is the intraoperative adaptation of preoperative datasets (MRI or CT) in order to compensate for "brain shift" during neurosurgical operations.

Algorithms↗

PubMed2000

Quantification of, visualization of, and compensation for brain shift using intraoperative magnetic resonance imaging.

OBJECTIVE: Modern neuronavigation systems lack spatial accuracy during ongoing surgical procedures because of increasing brain deformation, known as brain shift. Intraoperative magnetic resonance imaging was used for quantitative analysis and visualization of this phenomenon. METHODS: For a total of 64 patients, we used a 0.2-T, open-configuration, magnetic resonance imaging scanner, located in an operating theater, for pre- and intraoperative imaging. The three-dimensional imaging data were aligned using rigid registration methods. The maximal displacements of the brain surface, deep tumor margin, and midline structures were measured. Brain shift was observed in two-dimensional image planes using split-screen or overlay techniques, and three-dimensional, color-coded, deformable surface-based data were computed. In selected cases, intraoperative images were transferred to the neuronavigation system to compensate for the effects of brain shift. RESULTS: The results demonstrated that there was great variability in brain shift, ranging up to 24 mm for cortical displacement and exceeding 3 mm for the deep tumor margin in 66% of all cases. Brain shift was influenced by tissue characteristics, intraoperative patient positioning, opening of the ventricular system, craniotomy size, and resected volume. Intraoperative neuronavigation updating (n = 14) compensated for brain shift, resulting in reliable navigation with high accuracy. CONCLUSION: Without brain shift compensation, neuronavigation systems cannot be trusted at critical steps of the surgical procedure, e.g., identification of the deep tumor margin. Intraoperative imaging allows not only evaluation of and compensation for brain shift but also assessment of the quality of mathematical models that attempt to describe and compensate for brain shift.

Adolescent↗

PubMed2002

Localisation of the sensorimotor cortex during surgery for brain tumours: feasibility and waveform patterns of somatosensory evoked potentials.

OBJECTIVE: Intraoperative localisation of the sensorimotor cortex using the phase reversal of somatosensory evoked potentials (SEPs) is an essential tool for surgery in and around the perirolandic gyri, but unsuccessful and perplexing results have been reported. This study examines the effect of tumour masses on the waveform characteristics and feasibility of SEP compared with functional neuronavigation and electrical motor cortex mapping. METHODS: In 230 patients with tumours of the sensorimotor region the SEP phase reversal of N20-P20 was recorded from the exposed cortex using a subdural grid or strip electrode. In one subgroup of 80 patients functional neuronavigation was performed with motor and sensory magnetic source imaging and in one subgroup of 40 patients the motor cortex hand area was localised by electrical stimulation mapping. RESULTS: The intraoperative SEP method was successful in 92% of all patients, it could be shown that the success rate rather depended on the location of the lesion than on preoperative neurological deficits. In 13% of the patients with postcentral tumours no N20-P20 phase reversal was recorded but characteristic polyphasic and high amplitude waves at 25 ms and later made the identification of the postcentral gyrus possible nevertheless. Electrical mapping of the motor cortex took up to 30 minutes until a clear result was obtained. It was successful in 37 patients, but failed in three patients with precentral and central lesions. Functional neuronavigation indicating the tumour margins and the motor and sensory evoked fields was possible in all patients. CONCLUSION: The SEP phase reversal of N20-P20 is a simple and reliable technique, but the success rate is much lower in large central and postcentral tumours. With the use of polyphasic late waveforms the sensorimotor cortex may be localised. By contrast with motor electrical mapping it is less time consuming. Functional neuronavigation is a desirable tool for both preoperative surgical planning and intraoperative use during surgery on perirolandic tumours, but compensation for brain shift, accuracy, and cost effectiveness are still a matter for discussion.

Adolescent↗

PubMed1999

Image-guided procedures in brain biopsy.

Image-guided procedures, such as computed tomography (CT)-guided stereotactic and ultrasound-guided methods, can assist neurosurgeons in localizing the relevant pathology. The characteristics of image-guided procedures are important for their appropriate use, especially in brain biopsy. This study reviewed the results of various image-guided brain biopsies to ascertain the advantages and disadvantages. Brain biopsies assisted by CT-guided stereotactic, ultrasound-guided, Neuronavigator-guided, and the combination of ultrasound and Neuronavigator-guided procedures were carried out in seven, eight, one, and three patients, respectively. Four patients underwent open biopsy without a guiding system. Twenty of 23 patients had a satisfactory diagnosis after the initial biopsy. Three patients failed to have a definitive diagnosis after the initial procedure, one due to insufficient volume sampling after CT-guided procedure, and two due to localization failure by ultrasound because the lesions were nonechogenic. All patients who underwent biopsy using the combination of ultrasound and Neuronavigator-guided methods had a satisfactory result. The CT-guided procedure provided an efficient method of approaching any intracranial target and was appropriate for the diagnosis of hypodense lesions, but tissue sampling was sometimes not sufficient to achieve a satisfactory diagnosis. The ultrasound-guided procedure was suitable for the investigation of hyperdense lesions, but was difficult to localize nonechogenic lesions. The combination of ultrasound and Neuronavigator methods improved the diagnostic accuracy even in nonechogenic lesions such as malignant lymphoma. Therefore, it is essential to choose the most appropriate guiding method for brain biopsy according to the radiological nature of the lesions.

Aged↗

PubMedDate not supplied

[Diagnosis of brain gliomas in stereotactic biopsy assisted by optical neuro-navigation system].

BACKGROUND AND PURPOSE: Recently, stereotactic procedures of brain tumours have been enriched by an optical neuronavigation system, enabling us to assess the tumour location and size by means of three-dimensional magnetic resonance imaging (MRI). The aim of the study was to check which areas of brain gliomas would be most useful in neuropathological diagnosis of the material taken during stereotactic biopsy. We also analysed whether the MRI processed in the computerised neuronavigation system would be reliable in determination of a safety margin of glioma resection. MATERIAL AND METHODS: Material from the stereotactic biopsy has been examined neuropathologically by means of the Stealth Station navigation system. Tissue specimens were taken from the centre of neoplasm, its intermediate area, edge of the tumour and the nearest vicinity of neoplasm. 2-3 specimens in each area of the tumour were taken. The material was fixed in buffered formalin and embedded in paraffin and then stained with hematoxylin and immunostained for GFAP, cytokeratin and vimentin. RESULTS: Astrocytomas II were diagnosed in 17 cases, including fibrillary astrocytoma in 13 cases and gemistocytic astrocytoma in 2 cases. In other cases protoplasmatic astrocytomas were suspected. In 6 cases anaplastic astrocytoma and in 16 cases glioblastoma multiforme were diagnosed. In 3 cases the degree of malignancy was not possible to be defined. In 2 cases the neoplasm was not found. "Sensitivity" of the method was 91.1% and its "specificity" was 82.2%. The best results were achieved analysing the material from the intermediate area of neoplasm. There was the lowest number of "false negative" diagnostic results in this area. A few positive results were found in the central area and a high number of results (almost 50%) could be defined as "negative", assuming the specimens with no neoplastic cells. In more than 40% of biopsies from the edge of the tumour, neoplasm was not found, while in more than 20% of biopsies from the nearest vicinity of the tumour, neoplastic cells were present. CONCLUSIONS: Intermediate zone of brain gliomas located between its central parts and the tumour edge appears to be the most appropriate neoplastic area for diagnostic stereotactic biopsy assisted by the optical neuronavigation system. Because of infiltrative character of brain gliomas as well as their real dislocation during surgical procedure compared to the position based on the earlier neuroimaging, the territories considered in the optical neuronavigation system as the vicinity or neoplastic edge, run a risk of neuropathological misdiagnosis in this biopsy.

Adolescent↗

PubMed2002

Comparison of functional brain PET images and intraoperative brain-mapping data using image-guided surgery.

OBJECTIVE: Knowledge about the spatial localization of eloquent brain areas is essential for resecting lesions in the vicinity of these areas. The classical approach is to perform surgery on the awake patient under local anesthesia using brain-mapping techniques. As an alternative, the location of eloquent areas can be visualized by preoperative functional brain-imaging techniques, for example, positron emission tomography (PET), functional magnetic resonance imaging (fMRI), or magnetoencephalography (MEG). Using functional activation PET, both methods were combined by integration into a frameless navigation system (BrainLAB) and used to map speech-eloquent areas. PATIENTS AND METHODS: Speech-eloquent areas were localized preoperatively in seven patients with a left-sided glioma using 2-[(18)F]-2-desoxy-D-glucose PET. Patients were scanned under silence conditions (i.e., with the patient remaining silent in a sound-proof cabin), and speech was activated using a verb-generation paradigm. The PET data were transferred to the neuronavigation workstation and matched with a preoperative 3D-MRI using an automatic image-fusion algorithm. Intraoperative speech localization was performed using brain-mapping techniques under local anesthesia with bipolar cortical stimulation. The stimulator position was mapped into the MRI/PET data set by neuronavigational tracking of the instrument. RESULTS: Functional PET images were integrated into the MRI-based neuronavigational system and could be transferred exactly to the operative field. By the additional integration of cortical stimulation, intraoperative electrophysiological findings can be directly compared with preoperative functional images. Seven patients with left-sided glioma were operated on using this protocol, confirming the technical feasibility. In three of seven patients, preoperative PET findings were not supported by intraoperative mapping. CONCLUSIONS: This matching and mapping technique is suitable for monitoring eloquent speech areas during surgical resection of extensive left-sided low-grade gliomas, allowing a direct comparison between intraoperative electrophysiological brain mapping and preoperative functional brain-imaging findings. The sensitivity and specificity of functional imaging techniques can now be evaluated by reconciling the data with the intraoperative stimulation results.

Adult↗