Showing papers on "Neuronavigation published in 2004"

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

Abstract: PURPOSE: To review the initial clinical experience with intraoperative high-field-strength magnetic resonance (MR) imaging of brain lesions in 200 patients. MATERIALS AND METHODS: Two hundred patients (mean age, 46.1 years; range, 7–84 years), most of whom had glioma or pituitary adenoma, were examined with a 1.5-T MR imager equipped with a rotating operating table and located in a radiofrequency-shielded operating theater. A navigation microscope placed inside the 0.5-mT zone and used in combination with a ceiling-mounted navigation system enabled integrated microscope-based neuronavigation. The extent of resection depicted at intraoperative imaging, the surgical consequences of intraoperative imaging, and the clinical practicability of the operating room setup were analyzed. RESULTS: Seventy-seven resections with a transsphenoidal approach, 100 craniotomies, and 23 burr-hole procedures were performed. In 55 (27.5%) of 200 patients, intraoperative MR imaging had immediate surgical consequences (eg, exten...

Course of brain shift during microsurgical resection of supratentorial cerebral lesions: limits of conventional neuronavigation

Abstract: Background. The authors have conducted a prospective study to evaluate the amount and course of brain shift during microsurgical removal of supratentorial cerebral lesions, and to assess factors which potentially influence these shifts.

Clinical Article Course of brain shift during microsurgical resection of supratentorial cerebral lesions: limits of conventional neuronavigation

Abstract: SummaryBackground. The authors have conducted a prospective study to evaluate the amount and course of brain shift during microsurgical removal of supratentorial cerebral lesions, and to assess factors which potentially influence these shifts. Method. In 61 patients the displacement of 2–3 cortical landmarks on the cerebral surface was dynamically quantified during surgery, i.e. during dissection of the tumour at the estimated half-time of surgery, and at the end of microsurgical removal of the cerebral lesion using the neuronavigation system EasyGuide Neuro™. In 14 of these patients the displacement of a subcortical landmark was additionally analysed. Age of the patients, preoperative midline shift, location of the lesion, lesion volume, depth of the lesion below the cortical surface, presence or absence of oedema, and size of the craniotomy were analysed for potential influence on the amount of brain shift. Correlations were analysed for all patients together and for the subgroups of vault meningiomas (n=10), gliomas (n=30), and nonglial intra-axial lesions (n=21). Findings. The mean displacement of the cortical landmarks ranged between 0.8 and 14.3 mm (mean: 6.1 mm, standard deviation: 3.4 mm) during surgery (10–210 minutes [mean: 50.7 minutes, standard deviation: 34.5 minutes] after dura opening) and between 2.4 and 15.2 mm (mean: 6.6 mm, standard deviation: 3.2 mm) at the end of microsurgical removal of the tumourous cerebral lesions (20–375 minutes [mean: 107.2 minutes, standard deviation: 65.6 minutes] after dura opening). Significant correlations (p<0.01) for the entire patient group were found between brain shift and tumour volume, midline shift, and size of the craniotomy, respectively. For the subgroup of vault meningiomas a significant correlation (p<0.01) between brain shift and patient age was found. For the subgroup of gliomas a significant correlation (p<0.01) between brain shift and tumour volume, midline shift and size of the craniotomy, respectively, was found. For the subgroup of nonglial intra-axial lesions a significant correlation (p<0.01) between brain shift and midline shift and between brain shift and size of the craniotomy was found. The quantity of shared common variance ranged between 10–50%. Performing a discriminant analysis, lesion volume was the only certain factor influencing brain shift intra-operatively as well as at the end of lesion removal. 58.5% of the extent of brain shift could be correctly classified by the tumour volume as the only discriminating variable during dissection of the tumour and at the end of surgery.Comparing superficial with subcortical brain shift over the same time period, a mean superficial shift of 4.6 mm (1.6–10.8 mm, standard deviation: 2.8 mm) and a mean subcortical shift of 3.5 mm (1.0–7.7 mm, standard deviation: 2.3 mm) was found. A highly significant Spearman correlation (Rho: .97, p<0.001) between superficial and subcortical brain shift emerged. Shifting of superficial landmarks exceeded shifting of subcortical structures in all patients. Conclusions. The data demonstrate the dynamics of brain shift and the limits of conventional neuronavigation and add additional support for the unavoidable inaccuracy of contemporary neuronavigational systems once the cranium is opened. Brain shift leads to a significant loss of reliability of neuronavigation systems during microsurgical removal of intracranial lesions and there are differences of the course and the amount of brain shift in relation to special subgroups of supratentorial cerebral lesions. However, because of the heterogeneous nature of lesions neurosurgeons have to remove, the modest quantity of shared common variance, and the differences between superficial and subcortical brain shift, it seems unlikely that the amount and course of brain shift become exactly predictable pre-operatively. Only an intra-operative update of image data should have the capacity to overcome this fundamental problem of modern neuronavigation.

Functional magnetic resonance imaging-integrated neuronavigation: correlation between lesion-to-motor cortex distance and outcome.

Abstract: OBJECTIVE: The integration of functional magnetic resonance imaging (fMRI) data into neuronavigation is a new concept for surgery adjacent to the motor cortex. However, the clinical value remains to be defined. In this study, we investigated the correlation between the lesion-to-fMRI activation distance and the occurrence of a new postoperative deficit. METHODS: fMRI-integrated "functional" neuronavigation was used for surgery around the motor strip in 54 patients. During standardized paradigms for hand, foot, and tongue movements, echo-planar imaging T2* blood oxygen level-dependent sequences were acquired and processed with BrainVoyager 2000 software (Brain Innovation, Maastricht, The Netherlands). Neuronavigation was performed with the VectorVision(2) system (BrainLAB, Heimstetten, Germany). For outcome analysis, patient age, histological findings, size of lesion, distance to the fMRI areas, preoperative and postoperative Karnofsky index, postoperative motor deficit, and type of resection were analyzed. RESULTS: In 45 patients, a gross total resection (>95%) was performed, and for 9 lesions (low-grade glioma, 4; glioblastoma, 5), a subtotal resection (80-95%) was achieved. The neurological outcome improved in 16 patients (29.6%), was unchanged in 29 patients (53.7%), and deteriorated in 9 patients (16.7%). Significant predictors of a new neurological deficit were a lesion-to-activation distance of less than 5 mm (P < 0.01) and incomplete resection (P < 0.05). CONCLUSION: fMRI-integrated neuronavigation is a useful concept to assess the risk of a new motor deficit after surgery. Our data suggest that a lesion-to-activation distance of less than 5 mm is associated with a higher risk of neurological deterioration. Within a 10-mm range, cortical stimulation should be performed. For a lesion-to-activation distance of more than 10 mm, a complete resection can be achieved safely. The visualization of fiber tracks is desirable to complete the representation of the motor system.

Functional magnetic resonance imaging for neurosurgical planning in neurooncology.

Abstract: Functional magnetic resonance imaging (fMRI) is a non-invasive technique that is widely available and can be used to determine the spatial relationships between tumor tissue and eloquent brain areas. Within certain limits, this functional information can be applied in the field of neurosurgery as a pre-operative mapping tool to minimize damage to eloquent brain areas. In this article, we review the literature on the use of fMRI for neurosurgical planning. The issues addressed are: (1) stimulation paradigms, (2) the influence of tumors on the blood oxygenation level-dependent (BOLD) signal, (3) post-processing the fMRI time course, (4) integration of fMRI results into neuronavigation systems, (5) the accuracy of fMRI and (6) fMRI compared to intra-operative mapping (IOM).

Application of three-tesla magnetic resonance imaging for diagnosis and surgery of sellar lesions

Abstract: Object The aim of this study was to determine the value of high-field magnetic resonance (MR) imaging for diagnosis and surgery of sellar lesions. Methods High-field MR images were obtained using a 3-tesla unit with emphasis on sellar and parasellar structures in 21 patients preoperatively to delineate endo-, supra-, and parasellar anatomical structures. Special attention was given to the medial border of the cavernous sinus and possible invasion of a sellar tumor therein, and to assessing the application of high-resolution images during intraoperative neuronavigation. The 3-tesla MR images were compared with the standard MR images already obtained and with intraoperative findings. Anatomical structures were studied in all 42 cavernous sinuses; in 32 of them comparisons with intraoperative findings were possible. The medial cavernous sinus border was rated intact in 53% on standard MR images, in 72% on 3-tesla MR images, and in 81% intraoperatively. With a positive correlation to surgical findings on 84% ...

Intraoperative Iso-C C-arm navigation in cervical spinal surgery: review of the first 52 cases.

Abstract: Study Design. Fifty-two study participants underwent ceryical spine surgery using intraoperative Iso-C imaging with or without spinal navigation. Objectives. To evaluate prospectively the feasibility, sevantages. limitations, and applications of Iso-C in cervical spine surgery, Summary of Background Data. Existing stereotactic spinal navigational systems images must be acquired before surgery and typically require cumbersome point-to-point registration. intraoperative computed tomography (CT) and magnetic resonance imaging (MRI) provide real-time information but can restrict access to the patient, preclude the use of traditional operating room tables, and are time-consuming. The Iso-C allows quick, CT-quality, real-tiem data acquisition without restricting access to the patient. The data acquired can be automatically transferred to navigational systems with the immediate ability to navigate for anterior or posterior cervical spine procedures. Methods. High-resolution isotropic three-dimensional data sets were acquired using the Iso-C intraoperative fluoroscopy in 52 cervical spine cases. In 30 cases, the data were imported automatically to the StealthStation Treon to support neuronavigation. In 22 cases, a postprocedural intraoperative CT was obtained with the Iso-C primarily to assess the extent of osseous decompression and/or the accuracy of implants or instrumentation. In most cases, a postoperative high-resolution CT image was obtained and compared with the Iso-C data. Results. Successful automated registration suitable for navigation was attained for all anterior and posterior cervical spinal cases. The postprocedural intraoperative Iso-C data were 100% concordant with those of postoperative high-resolution CT as determined by a blinded neuroradiologist. Conclusions. Iso-C intraoperative fluoroscopy is an accurate and rapid way to perform CT-quality image-guided navigation in cervical spinal surgery. In most cases, it obviates the need for postoperative imaging.

Neuroendoscopic surgery of intracranial cysts in adults

Abstract: The purpose of this study was to describe the indications, surgical techniques and postoperative outcome of neuroendoscopic interventions in a heterogeneous group of intracranial cystic pathologies. Between 1992 and 2003, 127 patients with symptomatic intracranial cysts and cystic tumours underwent neuroendoscopic treatment in our department. In 22 patients indication for surgery was colloid cysts, in 9 patients pineal cysts and in 3 patients cavum vergae cysts. Twelve arachnoid cysts, 10 cystic craniopharyngiomas, 2 Rathke’s cleft cysts and 69 malignant cystic tumours were operated on. The patients’ mean age was 45 years and their clinical presentations varied from typical signs of increased intracranial pressure to focal neurological deficits. One hundred and twenty-seven patients with intracerebral cystic space-occupying lesions were operated on using stereotactic frameless or frame-based endoscopic techniques. There was no operative mortality. The operative morbidity was 3.1% including 1 memory deficit due to fornix injury, 1 hemiparesis due to postoperative haematoma after lesion biopsy, 1 aseptic meningitis and 1 subdural fluid collection. Endoscopic interventions enable neurosurgeons to manage intracranial cystic lesions. Via the same approach, the obstructed CSF pathways may be restored and consequently the increased intracranial pressure diminishes. With the aid of stereotactic guidance or a neuronavigation system, access to the lesion can be gained rapidly and with high accuracy.

Functional neuronavigation and intraoperative MRI.

Abstract: Our concept of computer assisted surgery is based on the combination of intraoperative magnetic resonance (MR) imaging with microscope-based neuronavigation, providing anatomical and functional guidance simultaneously. Intraoperative imaging evaluates the extent of a resection, while the additional use of functional neuronavigation, which displays the position of eloquent brain areas in the operative field, prevents increasing neurological deficits, which would otherwise result from extended resections.

Impact of neuronavigation and image-guided extensive resection for adult patients with supratentorial malignant astrocytomas: a single-institution retrospective study.

Abstract: Neuronavigation has become an effective therapeutic modality and is used routinely for intra-axial tumor removal. This retrospective study was conducted to evaluate the clinical impact of neuronavigation and image-guided extensive resection for adult patients with supratentorial malignant astrocytomas. Between 1990 and 2002, 76 adult patients with pathologically confirmed malignant astrocytomas underwent craniotomy and removal of the tumors at the Toyama Medical and Pharmaceutical University Hospital. Of these 76 patients, 42 were treated using neuronavigation with conventional microneurosurgery and the other 34 were treated with conventional microneurosurgery alone. Postoperative early MRI with contrast enhancement was done, and gross total resection was defined as the complete absence of residual tumor. Survival time was analyzed with the Kaplan-Meier method. Prognostic factors were obtained from the Cox proportional hazards model. In univariate analysis, age ( /= 80), use of neuronavigation, and gross total resection were significantly associated with longer survival. However, when the data were submitted to multivariate analysis, grade 3, preoperative KPS (>/= 80), and gross total resection were independent prognostic factors. The median survival periods of patients receiving gross total resection (vs. partial resection) and neuronavigation (vs. no neuronavigation) were 16 (vs. 9) months and 16 (vs. 10) months, respectively. The percentage of a gross total resection was significantly higher in the neuronavigation group compared to that in the no-navigation group (64.3 % vs. 38.2 %, p < 0.05). Neurological deterioration occurred in 4 of 42 (9.5 %) and in 6 of 34 (17.6 %) patients after surgery with neuronavigation and surgery without neuronavigation, respectively, although this difference was not statistically significant. Our results showed that neuronavigation increases the radicality in the resection of malignant astrocytomas and is objectively useful for improving survival time.

Three-dimensionally reconstructed magnetic source imaging and neuronavigation in pediatric epilepsy: technical note.

Abstract: OBJECTIVE: To determine the role of reconstructing three-dimensional magnetic source imaging (MSI) data on cortical resections for children undergoing epllepsy surgery using neuronavigation. METHODS: Magnetoencephalographic recordings were analyzed in 16 children under 18 years of age with intractable epliepsy. The data were transferred to the neuronavigation workstation for intranperative localization of MSI spike sources in selected patients. With the aid of neuronavigation, the MSI spike sources were resected. Intraoperative electrocorticography was then used to survey the surrounding field for residual epileptilorm activity. RESULTS: MSI spike sources were obtained in 13 of 16 patients. MSI spike sources localized the cortical and subcortical discharges before intraoperative electrocortic ography in mine patients and before extraoperative subdural grid electroencephalographic monitoring in four patients. The localization of MSI spikes sources was characterized by clustered spike sources in 10 patients. By use of neuronavigatice, the clustered spike sources were conelated to the interictal zone indicated by intraoperative electrocurticography in six patients and to the ictal onset zone shown on extraoperative subdutal grid electroencephalography in three patients. Cortical excision of the spike cinster focus was then performed in these six patients. The technique used here to resect MSI spike source clusters that correlate with the ictal onset zone by invasive subdural grid monitoring is illustrated in one patient who underwent cortical resection for epilepsy surgery. CONCLUSION; Three-dimensional reconstruction of MSI data linked to neuronavigatic is a promising inchnique to facilitate resections around eloquent cortes in children with epilepsy.

Neuronavigation-guided endoscopic surgery for pineal tumors with hydrocephalus.

Abstract: We have applied the neuronavigation system to endoscopic biopsy and third ventriculostomy in the management of patients with a pineal tumor with hydrocephalus. With the guidance of neuronavigation, the two optimal sites of burr hole and trajectories were planned preoperatively, and the advancing endoscopic device was monitored in real time during the procedure. In our five patients, the diameters of the tumors were 2-3 cm, and the mean systemic accuracy of registration with neuronavigation was 1.2 mm. The biopsy and third ventriculostomy were performed successfully via the respective optimal burr hole and the trajectory determined using preoperative neuronavigation. There were no procedure-related complications, and none of the patients needed another procedure for CSF diversion during the follow-up periods. We present our technique which includes the application of the neuronavigation system to the biopsy and third ventriculostomy in pineal tumor with associated hydrocephalus. This technique can be performed using a simple rigid endoscope via the determined optimal entries and trajectories. The optimal preoperative planning and the intraoperative guidance by neuronavigation are thought to be able to give more chances to minimize the brain injury related to movements or deviation of endoscopic device.

Intracranial neuronavigation with intraoperative magnetic resonance imaging

Abstract: Purpose of review This is an invited review regarding the use of intraoperative magnetic resonance imaging in the neurosurgical setting. The medical literature evaluating the intraoperative use of magnetic resonance imaging for neurosurgery has increased steadily since the implementation of this technique 10 years ago. The present review discusses recent findings and the current use of intraoperative magnetic resonance imaging in neurosurgery with special emphasis on the quality of available evidence. Recent findings Intraoperative use of magnetic resonance imaging is a safe technique that enables the neurosurgeon to update data sets for navigational systems, to evaluate the extent of tumor resection and modify surgery if necessary, to guide instruments to the site of the lesion, and to evaluate the presence of intraoperative complications at the end of surgery. Although recent findings support the safety and efficacy of intraoperative magnetic resonance imaging for the above-mentioned purposes, there is no convincing evidence regarding its prognostic significance in the neurosurgical setting. Summary Although the use of intraoperative magnetic resonance imaging in neurosurgery has increased significantly within the last 10 years, currently there are less than two dozen dedicated intraoperative units in the United States. The popularization of this technique depends on both economic justification and high-quality scientific evidence supporting its prognostic importance regarding patient outcome.

The evolution of stereotactic guidance in neuroendoscopy

Abstract: Objectives To evaluate the advantages and limitations of the utilized system in accordance with the operative indications of stereotactic neuroendoscopy.

Clinical outcome of epilepsy surgery.

Abstract: PURPOSE OF REVIEW The outcome from current surgical methods of treating drug-resistant epilepsy will be considered, looking at changes in classical resective surgery and new methodology being introduced in the functional treatment of these patients. RECENT FINDINGS There is now class I evidence that temporal lobe surgery is effective. Sophisticated and appropriate magnetic resonance imaging sequences, together with an assessment of the electroclinical syndrome, allow patients to be assessed for resective surgery. The concept of 'surgically remediable syndromes' determines the type of procedure that is effective for particular patients. Technical advances such as neuronavigation techniques and intra-operative magnetic resonance imaging have improved the effectiveness of these procedures. Other techniques of disconnection, such as multiple subpial transection, and stimulation both indirectly using the vagus nerve and directly using various intracranial targets, are currently effective and have potential for future development. SUMMARY This review will demonstrate that current surgical techniques are safe and effective in relieving drug-resistant epilepsy.

Neuronavigation and complication rate in epilepsy surgery.

Abstract: The role of neuronavigation for complications in temporal lobe epilepsy surgery was evaluated. Thirty-seven patients operated on with neuronavigation (group N: 38 operations; mean age 33.9 years; etiology: cryptogenetic 31, symptomatic 7; lateralization: 22 right, 16 left) and 22 patients operated on without neuronavigation (group NN: 23 operations; mean age 29.7 years; etiology: cryptogenetic 9, symptomatic 14; lateralization: 13 right; 10 left) were analyzed. The minimal follow-up time was 2 years. There was a clear difference in the number of complications (N 7.9%; NN 21.7%), which consisted of hemiparesis (N: 1; NN: 2), cranial nerve palsy (N: 1; NN: 2), aphasia (N: 1; NN: 0), and postoperative infection (N: 0; NN: 1). In addition, there was a reduced need for temporal re-resection after intraoperative electrocorticography (N 30.6%; NN 47.1%). Operation time (N: 239±9.4 min; NN: 208±12.1 min), duration of postoperative in-hospital and in-ICU stay [N: 16.9±1.1 days (1.0±0.0 days); NN: 17.2±2.8 days (1.1±0.1 days)], extension of temporal lobe resection from polar (N: 41.2±1.5 cm; NN: 42.9±3.9 cm), and postoperative seizure frequency reduction (N 90.4%; NN 94.7%) were not different. Because of the trend towards a reduction of complications and re-resections after electrocorticography, the authors recommend neuronavigation despite its higher costs as an additional tool in epilepsy surgery.

Intraoperative Image-Guided Surgery of the Lateral and Anterior Skull Base in Patients with Tumors or Trauma.

Abstract: The aim of this investigation was to evaluate the suitability and usefulness of the Stealth Station™ intraoperative guiding system (Medtronic Sofamor Danek, Memphis, TN) in a variety of indications. Eleven intraoperative image–guided procedures were performed for anterior or lateral skull base lesions. The most common neurosurgical approaches included frontal, coronal, and parietotemporal access. Neuronavigation reliably allowed the extent of tumor configuration and risk zones (e.g., blood vessels) to be visualized. Thus, gross tumor resection was achieved in 6 of 7 patients and facilitated reconstruction by the maxillofacial surgeon, resulting in radiologically symmetrical and clinically satisfying results. Postoperatively, one patient was blind from a continuity defect of the optic nerve caused by a bone fragment. Despite destruction of anatomical landmarks related to tumor invasion or intraoperative bone removal, neuronavigation proved helpful in the reconstruction of bony structures. Overall, the use of neuronavigation in interdisciplinary surgery for complicated tumors or trauma of the anterior or lateral skull base allows more radical resection associated with less morbidity.

Combined minimal invasive techniques in deep supratentorial intracerebral haematomas.

Abstract: 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.

Image-guided motor cortex stimulation in patients with central pain.

Abstract: According to recent clinical data, motor cortex stimulation (MCS) is an alternative treatment for central pain syndromes. We present our minimally invasive technique of image guidance for the placement of the motor cortex-stimulating electrode and assess the clinical usefulness of both neuronavigation and vacuum headrest. Five patients suffering from central pain underwent MCS with the guidance of a frameless stereotactic system (Brain-Lab AG, Munich, Germany). The neuronavigation was used for identification of the precentral gyrus and accurate planning of the single burr hole. The exact location was reconfirmed by an intraoperative stimulation test. Postoperative clinical and neuroradiological evaluations were performed in each patient. The navigation system worked properly in all 5 neurosurgical cases. Determination of the placement of stimulating electrode was possible in every case. All patients obtained postoperative pain relief. No surgical complication occurred, and the postoperative course was uneventful in all patients. This preliminary experience may confirm image guidance as a useful tool for the surgery of MCS. Additionally, minimal and safe exposure can be achieved using a single burr hole and vacuum headrest.

Neuronavigation-assisted Cranial Reconstruction

Abstract: Objective Cranial defects resulting from congenital deformities, ablative resection of osseous tumors, traumatic injury, and destructive infectious lesions are often severe enough to warrant surgical reconstruction. In particular cases, satisfactory cosmetic results may be difficult to achieve because of the extent and location of the lesion. Methods We evaluated the role of neuronavigation for reconstruction of large cranial defects with prefabricated titanium and intraoperatively constructed neuronavigation-assisted polymethylmethacrylate implants. Results Neuronavigation-assisted cranial reconstruction was performed in 14 patients. Surgical procedure, illustrative cases, postoperative results, and apparent benefits of the technique are presented and discussed. In all patients, excellent cosmetic results were achieved. Conclusion In cranial reconstruction, neuronavigation is of value not only for intraoperative determination of resection margins but also for preoperative assessment and planning. The combination of navigation techniques with prefabricated or intraoperatively constructed implants enables achievement of excellent cosmetic results.

Real-time integration of ultrasound into neuronavigation: technical accuracy using a light-emitting-diode-based navigation system

Abstract: Background. In brain surgery, intraoperative brain deformation is the major source of postimaging inaccuracy of neuronavigation. For intraoperative imaging of brain deformation, we developed a platform for the integration of ultrasound imaging into a navigation system.

Transbasal approaches: surgical details, pitfalls and avoidances

Abstract: Lesions involving the anterior skull base and sphenoclival region are difficult surgical problems. This paper presents surgical details, pitfalls, avoidances and our experiences in the surgical treatment of lesions of the anterior skull base using neuronavigation. Between 1999 and 2003, 33 patients with pathology of the anterior skull base were operated on via the traditional transbasal and the extended transbasal approach. A passive-marker-based neuronavigation system has been used for intraoperative image guidance since April 2000. The patients consisted of 11 men and 22 women. Their ages ranged from 3 to 76 years, with a mean of 41 years. The lesions for which the approach was used included 9 cerebrospinal fluid (CSF) fistulae and 24 neoplastic lesions including meningioma (16 cases), metastasis (3 cases), chordoma (3 cases), plasmacytoma (1 case), and osteoma (1 case). Gross total removal of the tumors was accomplished in 22 out of 24 patients with tumor (91.6%). Postoperative complications include CSF leakage (2 cases), infection (2 cases) and transient impaired vision (1 case). One patient (3%) died postoperatively from hypothalamic dysfunction after removal of a benign tumor extending to the anterior third ventricle. Despite the incidence of postoperative infection and the high rate of CSF leakage and death, it is possible to obtain long-term survival for patients with tumors previously considered challenging and difficult surgical problems.

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

Abstract: 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

Development and human factors analysis of neuronavigation vs. augmented reality.

Abstract: This paper is focused on the human factors analysis comparing a standard neuronavigation system with an augmented reality system. We use a passive articulated arm (Microscribe, Immersion technology) to track a calibrated end-effector mounted video camera. In real time, we superimpose the live video view with the synchronized graphical view of CT-derived segmented object(s) of interest within a phantom skull. Using the same robotic arm, we have developed a neuronavigation system able to show the end-effector of the arm on orthogonal CT scans. Both the AR and the neuronavigation systems have been shown to be within 3mm of accuracy. A human factors study was conducted in which subjects were asked to draw craniotomies and answer questions to gage their understanding of the phantom objects. The human factors study included 21 subjects and indicated that the subjects performed faster, with more accuracy and less errors using the Augmented Reality interface.

Integrating functional magnetic resonance imaging in neuronavigation surgery of brain tumors involving motor cortex

Abstract: OBJECTIVE To assess the value of integrating blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) in neuronavigation surgery of brain tumors involving motor cortex. METHODS A total of 58 patients with brain tumors in or directly adjacent to the motor cortex, with 18 lesions located in primary motor area, 18 lesions located in premotor area, 11 lesions located in primary motor sensory area, 9 lesions located in primary sensory area, and 2 lesions located in supplementary motor area respectively, were randomly divided into 2 groups: trial group including 30 cases undergoing BOLD navigation and control group with 28 cases undergoing routine navigation. A prospective random and matched controlled study was carried out to compare the clinical outcome between the two groups. For the patients in the trial group, the motor tasks consisted of simple flexion-extension finger movements and finger-to-thumb touching in a repeating, pre-planned sequence of either hand. A standard 1.5 T MR system had been utilized to localize the cortical motor hand area, using the BOLD contrast technique. The BOLD images were integrated with the routine navigational MR images (T1-weighted three-dimensional fast spoiled gradient recalled sequence), and then co-registered to the neuronavigation system. For the patients in the control group, the navigational MR imaging examinations were carried out only. RESULTS The statistics analysis confirmed a good balance of main variations between the trial and control groups. The percentage of completely resection of tumors was 86.7% in trial group and 60.7% in control group (P < 0.05). The postoperative contralateral extremities muscle strength were 4.3 +/- 1.1 degree for trial group and 2.5 +/- 1.9 degree for the control group (P < 0.01). The motor functional deficit was observed in 23.3% of the cases of trial group and 71.4% of the cases in trial group (P < 0.05). The mean Karnofsky prognosis scale of the trial group was 88 +/- 27, significantly higher than that of the control group (65 +/- 32, P < 0.01). CONCLUSION BOLD functional MR imaging is of great value in surgical planning and intraoperative functional brain mapping of motor cortex individually. To integrate BOLD data with the routine navigational MR images can supply more precise and real-time information about the relationship between lesions and neighboring cortical motor area. It should be used in neuronavigation surgery to increase the ratio of total resection of brain tumors and decrease the risk of postoperative hemiplegia.

Cavernous malformations--navigational supported surgery.

Abstract: 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 MRI 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.

The use of the neuronavigator in the orbital surgery of a rare case of Rosai-Dorfman disease.

Abstract: Neuronavigators are robotic devices that can help to bridge the gap between the data of three-dimensional images and the object by means of interactive computerized programs. A rare case of Rosai-Dorfman disease with prevalent bilateral endo-orbital interest is reported, in which an assisting neuronavigation system was used. The navigation system used is a stereotaxic system without the use of supporting mechanical arms, permitting bi-dimensional and tridimensional reconstruction through the data that are obtained from diagnostic equipment such as computed tomography, magnetic resonance imaging, single photon emission computed tomography, and positron emission tomography. This system has given an accurate localization of the pathological findings and has permitted a precise evaluation of the relation between the lesion and intraconical structures, which are fundamental requisites to optimize the treatment and reduce the postsurgical complications. The exciting results achieved in cerebral parenchyma surgery motivate extension of the use of neuronavigator systems to the splanchnocranial complex.