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PubMed1998

Postimaging brain distortion: magnitude, correlates, and impact on neuronavigation.

OBJECT: This prospective study was conducted to quantify brain shifts during open cranial surgery, to determine correlations between these shifts and image characteristics, and to assess the impact of postimaging brain distortion on neuronavigation. METHODS: During 48 operations, movements of the cortex on opening, the deep tumor margin, and the cortex at completion were measured relative to the preoperative image position with the aid of an image-guidance system. Bone surface offset was used to assess system accuracy and correct for registration errors. Preoperative images were examined for the presence of edema and to determine tumor volume, midline shift, and depth of the lesion below the skin surface. Results were analyzed for all cases together and separately for four tumor groups: 13 meningiomas, 18 gliomas, 11 nonglial intraaxial lesions, and six skull base lesions. For all 48 cases the mean shift of the cortex after dural opening was 4.6 mm, shift of the deep tumor margin was 5.1 mm, and shift of the cortex at completion was 6.7 mm. Each tumor group displayed unique patterns of shift, with significantly greater shift at depth in meningiomas than gliomas (p = 0.007) and significantly less shift in skull base cases than other groups (p = 0.003). Whereas the preoperative image characteristics correlating with shift of the cortex on opening were the presence of edema and depth of the tumor below skin surface, predictors of shift at depth were the presence of edema, the lesion volume, midline shift, and magnitude of shift of the cortex on opening. CONCLUSIONS: This study quantified intraoperative brain distortion, determined the different behavior of tumors in four pathological groups, and identified preoperative predictors of shift with which the reliability of neuronavigation may be estimated.

Adolescent↗
PubMed2002

Integration of sulcal and functional information for multimodal neuronavigation.

OBJECT: The authors present the use of cortical sulci, segmented from magnetic resonance (MR) imaging, and functional data from functional (f)MR imaging and magnetoencephalography (MEG) in the image-guided surgical management of lesions adjacent to the sensorimotor cortex. METHODS: In an initial set of 11 patients, sulci near lesions were automatically segmented from MR imaging data sets, then MEG and fMR imaging examinations were performed. Relevant functional information was preoperatively interpreted and selected from MEG and fMR imaging and subsequently transferred to the navigation system for selected sulci. A neuronavigation system consisting of a surgical microscope with enhanced reality overlay display was used. Data were displayed as contours on the cut-plane images of a stereotactic workstation and as contours on the overlay screen of the head-up display within the optical path of the right eyepiece of the surgical microscope. CONCLUSIONS: This method, in which both sulcal and functional mapping are used for surgery planning and neuronavigation, provides helpful information. It is a promising procedure for the treatment of patients who harbor lesions in areas around the eloquent cortex.

Adult↗
PubMed2000

[Treatment of central and neuropathic facial pain by chronic stimulation of the motor cortex: value of neuronavigation guidance systems for the localization of the motor cortex].

Thirty two patients with refractory central and neuropathic pain of peripheral origin were treated by chronic stimulation of the motor cortex between May 1993 and January 1997. The mean follow-up was 27. 3 months. The first 24 patients were operated according to the technique described by Tsubokawa. The last 13 cases (8 new patients and 5 reinterventions) were operated by a technique including localization by superficial CT reconstruction of the central region and neuronavigator guidance. The position of the central sulcus was confirmed by the use of intraoperative somatosensory evoked potentials. The somatotopic organisation of the motor cortex was established peroperatively by studying the motor responses at stimulation of the motor cortex through the dura. Ten of the 13 patients with central pain (77%) and nine of the 12 patients with neuropathic facial pain had experienced substantial pain relief (75%). One of the 3 patients with post-paraplegia pain was clearly improved. A satisfactory result was obtained in one patient with pain related to plexus avulsion and in one patient with pain related to intercostal herpes zoster. None of the patients developed epileptic seizures. The position of the stimulating poles effective on pain corresponded to the somatotopic representation of the motor cortex. The neuronavigator localization and guidance technique proved to be most useful identifying the appropriate portion of the motor gyrus. It also allowed the establishment of reliable correlations between electrophysiological-clinical and anatomical data which may be used to improve the clinical results and possibly to extend the indications of this technique.

Adult↗
PubMed2001

A comparative statistical analysis of neuronavigation systems in a clinical setting.

The use of neuronavigation (NN) in neurosurgery has become ubiquitous. A growing number of neurosurgeons are utilizing NN for a wide variety of purposes, including optimizing the surgical approach (macrosurgery) and locating small areas of interest (microsurgery). The goal of our team is to apply rapid advances in hardware and software technology to the field of NN, challenging and ultimately updating current NN assumptions. To identify possible areas in which new technology may improve the surgical applications of NN, we have assessed the accuracy of neuronavigational measurements in the Radionics and BrainLab systems. Using a phantom skull, we measured how accurate the visualization of a navigational probe's tip was in these systems, taking a total of 2180 measurements. We found that, despite current NN tenets, error is maximal at the six marker count and minimal in the spreaded marker setting; that is, placing less markers around the area of interest maximizes accuracy and active tracking does not necessarily increase accuracy. Comparing the two systems, we also found that accuracy of NN machines differs both overall and in different axes. As researchers continue to apply technological advances to the NN field, an increasing number of currently held tenets will be revised, making NN an even more useful tool in neurosurgery.

Factor Analysis, Statistical↗
PubMed2003

Intraoperative imaging in a comprehensive neuronavigation environment for minimally invasive brain tumour surgery.

BACKGROUND: Development of an image-guided operation theatre offering multimodal information for mini-invasive neurosurgical brain tumour operations. METHODS: A multi-purpose resistive low-field MR scanner with on-off capability, was installed in a radio frequency-shielded operating room with in-room control panel and display. Intraoperative ultrasound imaging with Doppler mode as needed is used to provide check-up image data between intraoperative MR-imaging sessions. Cortical stimulation and registration are performed during awake craniotomies. The neuronavigation systems are customised arm-based and passive optical. The navigation systems show the positions of the ultrasound probe, cortical stimulation electrode, biopsy needles, endoscope and other instruments on the intraoperative MR-images. FINDINGS: Since 1999, 70 patients (mean age 47, range 3-88 years) have been operated with intraoperative MR-guidance (including 10 tumour biopsies, 56 resections). Twenty-one patients (mean age 46, range 16-67 years) underwent awake craniotomy and tumour resection secured with cortical stimulation and usually preoperative fMR-imaging. The present operating environment offered useful multimodal information for surgery of brain tumours in critical locations. Surgical mortality was 0%, morbidity included 3 (4.3%) infections and 2 (2.9%) permanent hemiparesis. Further removal of tumour was continued in 17 cases (57%) out of the 30 cases where intraoperative MR imaging was used for controlling completeness of the resection.

Adolescent↗
PubMed2003

Image-guided removal of supratentorial cavernomas in critical brain areas: application of neuronavigation and intraoperative magnetic resonance imaging.

In a retrospective study the postoperative results of 26 patients operated on for supratentorial cavernous hemangiomas either deep-seated or near eloquent brain areas are summarized. An exact surgical approach to these lesions is essential to prevent neurological deterioration. Three different navigation systems were used and compared according to their clinical applicability. Complete removal of the lesion was obtained in all patients of this series. In six cases (23 %) functional data from magnetoencephalography or functional magnetic resonance imaging were integrated into the navigational setup. In 14 cases (54 %) intraoperative magnetic resonance imaging was performed. The follow-up time was 3 - 26 months (mean: 10 months). In the postoperative course one patient (3.8 %) developed a hemiparesis, another one developed quadrantopia. Nineteen patients presented with preoperative seizure history, 16 of these (84 %) had no further or rare seizures after surgery. The better results in seizure control were achieved in those patients with shorter duration of seizure history before surgery. The study indicates that the application of neuronavigation allows surgery on supratentorial cavernous hemangiomas in critical brain areas with low morbidity. The intraoperative visualization of eloquent cortex areas by integration of functional data allows a fast identification and exemption of eloquent brain areas, preventing neurological deterioration. Furthermore, the intraoperative MR resection control ensures a complete resection and illustrates the minimal invasive approach.

Adolescent↗
PubMed2003

Updating of neuronavigation based on images intraoperatively acquired with a mobile computerized tomographic scanner: technical note.

Image-guided surgery based on preoperatively obtained image data is susceptible to inaccuracy resulting from intraoperative brain shift and distortion. We report a technique of updating neuronavigational data with the aid of a mobile computerized tomographic (CT) scanner. A mobile CT which is readily available in an ordinary operating room was used to acquire intraoperative images. A total of 6 - 7 titanium screws placed on the skull were used as new reference points for updating navigation. Intraoperative CT scanning was performed with a 2 mm slice thickness. After the obtained image data were transferred as Dicom files to the computer workstation of the navigation system through an Ethernet connection, navigational data were updated to registering the new reference points. Under the guidance of the updated navigation, residual lesions were explored, and further resected. Our preliminary experience in 8 patients indicates that interactive image-guidance can stably be updated based on images intraoperatively acquired with a mobile CT scanner. Comparing to intraoperative magnetic resonance imaging, this technique can simply be done in an ordinary operating room without requiring special surgical instruments, thus making it possible to update interactive image guidance on demand during an operation.

Adult↗
PubMed2003

Neuronavigation based on CT angiography for surgery of intracranial aneurysms: primary experience with unruptured aneurysms.

Several reports have demonstrated the use of three-dimensional (3D) computed tomographic angiography (CTA) for preoperative planning in patients with intracranial aneurysms. Until now, there are no reports on the potential role of navigation systems in combination with CTA in aneurysm surgery. In the present study we report our experience with neuronavigation based on CTA in 16 patients with unruptured anterior circulation aneurysms for 1) planning craniotomy; 2) guided approach to the aneurysm; and 3) 3D presentation of the aneurysm and adjacent arteries in correct orientation. The reconstructed CTA images were analyzed preoperatively with regard to diameter of aneurysm neck and dome as well as projection and possible daughter aneurysms, and these parameters were compared with the intraoperative findings. In addition the accuracy of the navigator to locate the aneurysm neck was measured intraoperatively. Navigated approach planning resulted in variable keyhole craniotomies for the 7 middle cerebral artery aneurysms, but did not result in deviation from small standard craniotomies for the internal carotid and anterior communicating artery aneurysms. Precision of the indication of the navigator with regard to the aneurysm neck ranged from < 1 mm to 4 mm. Intraoperative assessment confirmed the CTA data with regard to aneurysm size and projection in all, and definition of daughter aneurysms and adjacent arteries in most cases. The computer assisted approach allowed a smaller, exactly placed craniotomy primarily in MCA aneurysms. 3D presentation of the aneurysms and the adjacent arteries in correct orientation facilitated identification and dissection the aneurysms. Current navigation systems are not precise enough to allow "blind" aneurysm clipping by placing a real clip on the virtual aneurysm neck.

Adult↗
PubMed2003

Experimental third ventriculostomy performed using endovascular surgical techniques and their adaptation to percutaneous intradural neuronavigation: proof of concept cadaver study.

OBJECTIVE: Endoscopic third ventriculostomy has developed into a therapeutic alternative to shunting for the management of carefully selected patients with primarily noncommunicating hydrocephalus. This procedure, however, requires a general anesthetic and necessitates violation of the brain parenchyma and manipulation near vital neural structures to access the floor of the third ventricle. Using two cadavers and off-the-shelf angiographic catheters, we sought to determine whether it was possible to navigate a catheter, angioplasty balloon, and stent percutaneously through the subarachnoid space from the thecal sac into the third ventricle so as to perform a third ventriculostomy from below. METHODS: Using biplane angiography and off-the-shelf angiographic catheters along with angioplasty balloons and stents, we were able to pass a stent coaxially from the thecal sac to and across the floor of the third ventricle so as to achieve a third ventriculostomy from below. RESULTS: Coaxial catheter techniques allowed for the percutaneous insertion of a stent across the floor of the third ventricle. Ventriculostomy was confirmed by injecting contrast medium into the lateral ventricle and seeing it pass through the stent and into the chiasmatic cistern. CONCLUSION: We describe the performance of third ventriculostomies in two cadavers by use of the new concept of percutaneous intradural neuronavigation. This procedure may obviate the need for general anesthetic and minimize the potential for brain and vascular injury, especially if ultimately combined with magnetic resonance fluoroscopy.

Adult↗
PubMedDate not supplied

[The results of applying the system of neuronavigation in the intracranial surgery].

Frameless stereotactic techniques combined with a high-resolution neuro-imaging made its possible for us to perform, with high reliability, interactive image-guided procedures. We used the Carl Zeiss Surgical Microscope Navigator System with Carl Zeiss OPMI NC-4 microscope. We reported our results on the first 82 patients during the 20-month period. 36 were males (44%), 46--females (56%) with the age range of 15 to 79 (mean 43.43). The predominant diagnosis was tumor (60 patients or 73.2%) with histological findings of astrocytoma and metastasis. The surgical procedure was open microneurosurgery. There were no significant technical problems. The clinical and surgical results were satisfying in all cases. 14 patients with secondary epilepsy, as the only symptom, were postoperatively seizure-free. Neuronavigation cuts the time of surgery and ensures a more radical resection of pathological tissue with lower mortality and morbidity thus improving the life quality of patients.

Adolescent↗
PubMed2001

Initial experience with an ultrasound-integrated single-RACK neuronavigation system.

A prototype ultrasound-integrated neuronavigation system was tested in 34 operations as regards image quality, stability, and handling during daily use in the operating theatre. The system consists of a high-end ultrasound scanner, a navigation computer, and an active optical positioning and digitiser system, all integrated in a single rack. An Ethernet interface between the two hardware devices enables digital data transfer between the ultrasound scanner and the navigation device without loss of image quality. The integration of an ultrasound scanner and a navigation device offers the opportunity of navigating directly to an intracranial or intraspinal lesion using intra-operative 3D ultrasound images. The brainshift problem is thus avoided. The ability to directly compare MR images and 3D ultrasound simplifies the interpretation of ultrasound images. The single-rack solution is an advantage in times of restricted space in the operating theatre caused by the increasing volume of technical equipment needed for a neurosurgical operation. In 30 cases the prototype system showed good reliability. In four cases the navigation system failed during the operation; however, the capacity of the ultrasound scanner was still available as a stand-alone function. With the single-rack concept, the flexibility of the system is high and the complete device can easily be moved from one operating theatre to another.

Equipment Design↗
PubMed2004

Identification and removal of an epileptogenic lesion using Ictal-EEG, functional-neuronavigation and electrocorticography.

PURPOSE: Cases with intractable epilepsy may present with multiple lesions in their brains. Ictal-EEG carries a great value in identification of the primary epileptogenic source. On the other hand, removal of low-grade tumors located around the eloquent cortex may be risky with conventional techniques. Functional-neuronavigation (f-NN) is the integration of functional magnetic resonance imaging and stereotactic technologies; and provides interactive data regarding localization of the motor cortex. This report presents a case with dysembryoplastic neuroepithelial tumor (DNET), which was removed using f-NN and electrocorticography (ECoG) techniques. METHODS: A 19-year-old patient with intractable complex partial and secondary generalized seizures is presented. MRI revealed a low-grade tumor located in right parietal region just behind the motor cortex, and a contralateral temporal arachnoid cyst. Ictal-EEG demonstrated the right parietal origin of the seizures. The patient underwent a right parietal craniotomy and tumor excision using f-NN and ECoG techniques intraoperatively. ECoG findings correlated with epileptogenicity of the parietal lesion. RESULTS: Postoperative course was uneventful. No postoperative deficit was observed. The patient was seizure free in eight months follow-up. Pathological examination reported the lesion as DNET. CONCLUSIONS: Ictal-EEG has a very important role in identification of the epileptogenic focus in cases with multiple brain lesions. Preservation of the functional cortex is the most prominent aim during lesional surgery of epilepsy. Intraoperative mapping using f-NN and ECoG supports the orientation of the neurosurgeon to the functional and epileptogenic cortical areas; and thus, increase the safety and efficacy of surgical procedures.

Electrodes, Implanted↗
PubMed2001

Transcranial magnetic stimulation in therapy studies: examination of the reliability of "standard" coil positioning by neuronavigation.

Transcranial magnetic stimulation is investigated as a new tool in the therapy of depression and other psychiatric disorders. In almost all studies, the dorsolateral prefrontal cortex (DLPFC) has been selected as the target site for stimulation. Usually this region was determined by identifying the patient's motor cortex, and from there the coil was placed 5 cm rostrally. The aim of our study was to test the reliability of this standard procedure. A neuronavigational system was used to relate the final coil position after applying the standard procedure to the individual cortical anatomy. In 7 of 22 subjects, the Brodman area 9 of the DLPFC was targeted correctly in this manner. In 15 subjects, the center of the coil was found to be located more dorsally (e.g., above the premotor cortex). The current method for locating the DLPFC is not precise anatomically and may be improved by navigating procedures taking individual anatomy into account.

Adult↗
PubMed2000

Accuracy and clinical applicability of a passive marker based frameless neuronavigation system.

A passive marker system permits the inclusion of an unlimited number of instruments and other devices during frameless stereotaxy. The aim of this study was to evaluate the accuracy and clinical applicability of a passive marker based frameless image guided system (VectorVision; BrainLab, Heimstetten, Germany) developed for surgical planning and intraoperative image guidance. The system was first applied to a plastic phantom to determine the accuracy of the system by measuring the difference between the actual probe position and its analogous position on the monitor screen. The navigational device was subsequently applied to 40 procedures for brain tumours and cavernomas. The mean error value between the image on the monitor screen and the real location in the phantom and the clinical study was 1.45 mm (+/-0.99) and 4.05 mm (+/-3.62), respectively. Many different instruments could be employed as pointing devices. It was helpful in minimising the size of the craniotomy. An average lengthening of the surgical procedure of 20 minutes was experienced. The neuronavigation system proved to be a useful surgical tool to approach and detect lesions larger than 5 mm in diameter. The passive marker technology is intuitive and enables the surgeon to use his or her own instruments at any time as a pointing device, thus avoiding further costs for specially designed surgical equipment.

Adult↗
PubMed2000

[Neuronavigation in the region of the skull base].

Neuronavigation (computer-aided surgery planning and performance) has proven to be helpful in performing neurosurgical operations. The experiences of our department gained on more than 500 patients operated upon will be presented, with special focus on more than 100 operations for lesions on the skull base. Navigation is one of several modern surgical tools, its value cannot be defined without observing other improvements e.g. in the area of preoperative diagnostics, intraoperative monitoring, microsurgical instruments and microsurgical approaches.

Adenoma↗
PubMed2001

The impact of an armless frameless neuronavigation system on routine brain tumour surgery: a prospective analysis of 51 cases.

A passive infrared armless and frameless neuronavigation system was introduced in routine intracranial and skull base surgery, and its impact on 51 cases in a one year period was assessed. No cases were rejected by the operating surgeon for lack of accuracy (> 3 mm). Operating time was not significantly lengthened, except in transphenoidal cases (255 +/- SD 168 min versus 185 +/- SD 119 min, p = 0.02). Length of stay was shorter in navigation cases in supratentorial glioma (12 +/- SD 7.3 days versus 15 +/- SD 7.9 days) and meningioma (11 +/- SD 5.3 days versus 16 +/- SD 6.7 days, p = 0.01). Outcome at 3 months was comparable in both the supratentorial glioma and meningioma group. Problems such as setup time and brain shift are addressed and discussed.

Adolescent↗
PubMed2000

Neuroendoscopy combined with frameless neuronavigation.

Minimal invasive neurosurgery is becoming more and more standard in neurosurgical procedures. Several types of lesions are now approached endoscopically. The surgical planning and intraoperative orientation during endoscopic surgical procedures are sometimes difficult. To solve this problem, a combination of the endoscopic procedure with a frameless, armless neuronavigation system is used in our service. The combination of the endoscope and the frameless navigation system was used in tumour surgery, ventriculostomies and arachnoid cyst operations. All procedures were performed successfully. The combination of both systems has proved to be advantageous because of safe surgical planning using the frameless stereotactic technique and the possibility of real time orientation of the endoscope. This technique is very useful in removing intraventricular and large brain mass lesions.

Arachnoid Cysts↗