Conventional Stereotaxy Research Articles

Framed and non-framed robotics in neurosurgery: A 10-year single-center experience.

Safety, efficacy and efficiency of neurosurgical robots are defined by their design (i.e., framed and non-framed) and procedural workflow (PW) (from image to surgery). The present study describes the quality indicators of three different robots in brain and spine surgery. This single-centre study enrolled 252 patients over a 10-year period. Safety (complication rate) and efficacy (diagnostic yield, pedicle screw placement) were determined. Predictors of workflow efficiency (e.g., skin-to-skin) were evaluated and compared to conventional techniques (neuronavigation, stereotaxy). All robots showed excellent reliability (97.5%-100%) with low complication rates (4.5%-5.3%) and high efficacy (94.7%-97.7%). Robotics demonstrated a better time-efficiency than neuronavigation. However, there was no shortening of surgery time compared to conventional stereotaxy. Time-efficiency differed significantly between framed and non-framed workflows. While all neurosurgical robots were reliable, safe and efficacious, there were significant differences in time-efficiency. PWs should be improved to increase the acceptance of robotics in neurosurgery.

Utilization of the Intraoperative Mobile AIRO® CT Scanner in Stereotactic Surgery: Workflow and Effectiveness

Background: In frame-based stereotactic surgery, intraoperative imaging is crucial. It generally follows a workflow including preoperative MRI and intraoperative frame-based CT. The intraoperative transport of the anesthetized and intubated patient to and from the CT unit can be time-consuming and cumbersome. Here, we report the first 50 patients who underwent stereotactic biopsies using the mobile AIRO® intraoperative CT (iCT) scanner. Methods: A conventional stereotactic frame was mounted to the AIRO® carbon table via carbon adapter. 0°gantry thin-slice iCT was performed. The imaging data were transferred to a conventional stereotaxy working unit. After fusion of the preoperative MRI and AIRO® iCT, the stereotactic system was built based on the iCT, and trajectories were calculated accordingly. Results: The frame-based stereotactic iCT was easy to implement and successfully accomplished in all patients. The MRI/iCT image fusion was feasible in all of the studies. A conclusive histological result was obtained in 46 of the 50 cases included. There was no bleeding complication. Net surgery time was reduced by 38 min, on average. Conclusion: We conclude that the AIRO® system is a safe, easy-to-use, and sufficiently accurate iCT for CT frame-based stereotactic biopsy planning that results in a considerable reduction of surgery time. In the future, it remains to be evaluated if the accuracy rates and intraoperative workflow will permit its application in deep brain stimulation and other functional procedures as well.

Stereo-EEG in children with therapy-refractory epilepsies: Robot-assistance plus stereotaxy combines speed with maximal precision for the implantation of multiple depth electrodes

Aims: “Stereo-EEG” is an invasive diagnostic procedure for the presurgical evaluation of therapy-refractory epilepsies, during which depth electrodes are implanted stereotactically into the brain parenchyma via multiple burr holes. A comprehensive evaluation often requires up to 20 depth electrodes in multiple brain areas, which can lead to long operations (20 to 30 minute per electrode) when conventional stereotaxy is used. Special assisting robots can make these implantations much faster (< 10 minute per electrode) by automatically defining the preplanned implantation trajectories for the surgeon. Without the use of a stereotaxic frame (“frameless”); however, the same precision as with conventional stereotaxy cannot be achieved. Here, we present the first cases of our new approach which combines both techniques, aiming at combining the speed of robot-assistance with the precision of conventional stereotaxy.

Finding the striatum in sheep: use of a multi-modal guided approach for convection enhanced delivery.

Our goal is delivery of a long-term treatment for Huntington's disease. We administer intracerebrally in sheep adeno-associated virus (AAV) to establish optimal safety, spread and neuronal uptake of AAV based therapeutics. Sheep have large gyrencephalic brains and offer the opportunity to study a transgenic Huntington's disease model. However, lack of a relevant brain stereotactic atlas and the difficulty of skull fixation make conventional stereotaxy unreliable. We describe a multi-modal image-guidance technique to achieve accurate placement of therapeutics into the sheep striatum.

Mikrochirurgische Entfernung tiefliegender Gefäßmißbildungen mit Hilfe der Sonar-Stereometrie

The advantages of a new, dynamic sonar technology in open stereotactic microsurgery are demonstrated by means of three surgical procedures for deep-seated vascular malformations that are not easy of access. With this method, targets can be aimed at without using rigid, obstructive pointing devices as in conventional stereotaxy. On the contrary, it is possible to take advantage of preformed anatomical spaces reaching the lesion most carefully by means of light-weight, free-hand on-target instruments. The spatial information, correlated with a CT data set, is displayed in real time with an accuracy of +/- 1 mm. Additional image data from MR and digital angiography can be used interactively.

A retrospective analysis of digital stereotaxis in breast screening

Digital imaging systems have been introduced into the assessment process for breast screening and should help to make the procedure quicker and reduce the trauma. However, there is concern that digital stereotaxis could have a negative impact on the accuracy of tissue sampling procedures. The objective of this study was to deduce the impact of digital stereotaxis on the assessment process in breast screening. A retrospective study was undertaken in 28 centres that performed assessments in the UK breast screening programme. Quality assurance (QA) data from 7750 women assessed using conventional stereotaxis (from 25 units) were compared with those from 4743 women assessed using digital stereotaxis (from 14 units). All the data relate to women having biopsies. The data used show the pre-operative result recorded at the core biopsy compared with the overall outcome after surgery. From this, QA parameters are calculated which are used to deduce the performance of screening programmes. Complete sensitivity, specificity (full), the positive predictive value (PPV) for B3 biopsies and the suspicious rate had statistically significant increases (p<0.05, p<0.01, p<0.05 and p<0.05, respectively) and the specificity (biopsy), false-negative rate and inadequate rate from cancers had statistically significant decreases (p<0.01, p<0.0005 and p<0.0005, respectively). One of the other QA measures improved to meet the target standard set, i.e. PPV (B5). It is concluded that digital stereotaxis has contributed to significant improvements in the assessment process, although the improvements shown in this study cannot be wholly attributed to the introduction of digital stereotaxis.

Use of an Open Stereotactic Ring for Neurosurgical Procedures

We describe an open ring as a new design to the Zamorano-Dujovny (Z-D) stereotactic unit. The titanium base ring has an opening of 45 degrees that can be located in any chosen position. Imaging studies such as computed tomography, X-ray, positron emission tomography, digital angiography, and digital substraction angiography can be performed with the open stereotactic ring for multimodality image localization. Preoperatively and intraoperatively, this open design provides the anesthesiologist with an unobstructed pathway for airway management. During the surgical procedure, it facilitates approach to any intracranial lesion, including orbitozygomatic, combined supra-infratentorial, and others. During awake craniotomies it not only allows for easy airway management, but also provides good access to the patient's face for intraoperative evaluation of speech and visual functions. Accuracy and reliability of this unit were similar to results obtained with the original circular ring. This system can be used in conventional stereotaxis with the Z-D arc, as well as a reference for intraoperative registration with any digitizer system. The open stereotactic unit is a relatively inexpensive, reliable, and easy-to-use solution for resections using conventional stereotaxis or interactive image guidance in any intracranial site.

A Stereotaxic Template Atlas of the Macaque Brain for Digital Imaging and Quantitative Neuroanatomy

A stereotaxic brain atlas of the longtailed macaque (Macaca fascicularis) is presented in a format suitable for use as a template atlas of the macaque brain. It includes most of the brain segmented to show the boundaries of landmark structures such that every point in the brain can be represented by a unique set of coordinates in three-dimensional space and ascribed unambiguously to one and only one primary structure. More than 400 structures are represented, including 360 volumetric structures, which constitute the substance of the brain, and 50 superficial features. To facilitate use with ventriculography, magnetic resonance imaging, and other noninvasive imaging techniques, the stereotaxic space is referenced to internal landmarks, viz., the anterior commissure and posterior commissure; the center of the anterior commissure at the midline is the origin of the stereotaxic axes. Reference of stereotaxis to this bicommissural space facilitates structural comparison with human brain atlases, which are commonly referenced to the biocommissural line. It also facilitates comparison of brains of different nonhuman primate species by providing a template brain against which to compare size and internal variability. Thirty-three coronal sections at 1-mm intervals from the spinomedullary junction to the rostral extreme of the caudate nucleus show most structures of the hindbrain, midbrain, and subcortical forebrain. Separately, four side views and 16 coronal sections show cortical structures. Structures are represented by outlines of their boundaries and labeled according to NeuroNames, a systematic English nomenclature of human and nonhuman primate neuroanatomy. Abbreviations are based on a protocol designed to facilitate cross-species comparisons. Instructions are provided for: (1) locating sites from the Template Atlas in the conventional stereotaxic space of an experimental animal, (2) locating sites identified by conventional stereotaxis in the Template Atlas, and (3) using the Template Atlas to collate, compare, and display image information (e.g., labeled cells, recording sites, stimulation sites, lesions) from multiple animals.

Computer assisted brain surgery for small lesions in the central sensorimotor region.

The capacity of a new optical navigation device is demonstrated by six microsurgical procedures for small subcortical lesions within the central sensorimotor strip. This small series is aimed at less invasive resection in this functionally critical region, independently of primary diagnosis and outcome. Guided by high resolution CT imaging data five brain tumours and one cavernous angioma was selectively located and most sparingly removed without additional sensorimotor deficit. In two cases improvement of a pre-operative paresis was observed immediately after surgery. Thanks to light-weight freehand pointing instruments and a ranging accuracy of +/- 1 mm, damage to functionally important brain areas and vessels was avoided by using uncommonly oblique, e.g., transsulcal ways of access which would hardly have been possible even with guidance by conventional stereotaxy. The demanding systematic cortical stimulation of the precentral gyrus applied in three cases was only sensitive in infiltrating tumours-e.g., low grade astrocytomas-where for want of adjuvant therapy it was essential to proceed to the extreme limits of resection. In general, precise anatomical localisation by computer aided surgery (CAS) is sufficient in small central lesions which guarantees minimally invasive surgery. The potential of this new, soon commercially available optical navigation system in (neuro) surgery, quality control and teaching is discussed.

The impact of interactive image guided surgery: the Bristol experience with the ISG/Elekta viewing Wand.

From June 1992 to August 1994 we have accumulated a 305 case experience with the ISG Viewing Wand, the first commercially available system for interactive image guided neurosurgery. Prior to the arrival of the wand 2.5% of intracranial procedures were carried out using the Leksell G frame for image guidance. Since the arrival of the wand that percentage of procedures suitable for image guidance has increased to 10%. The wand was used for 287 supratentorial procedures, 108 craniotomies, 48 trephine exposures, 34 burr hole biopsies, 4 ventriculoscopies and 1 shunt insertion, 19 posterior fossa explorations were performed, 28 skull base procedures, including 22 transsphenoidal pituitary operations, 3 petrousectomies and 3 orbital explorations were also carried out. In addition 3 spinal cases were included in the series, 2 transoral explorations and 1 sacral laminectomy. The technique was applicable to 193 tumour cases, 14 vascular cases including 7 aneurysms and 16 epilepsy cases. Both CT (70%) and MRI (30%) scans were used for image guidance. Contour matching algorithms were used for registration throughout. Since the arrival of the wand conventional stereotaxy has been used for 26 cases, 22 stereotactic biopsies, 2 thalamotomies and 2 craniotomies (0.5% of intracranial procedures). We conclude that contour matching, interactive image guidance using a mechanical arm has replaced frame based stereotaxy in our department except for point source localisation in deep midline structures. It is a technique that has universal application to intracranial neurosurgical procedures and as such represents a major advance in image guided neurosurgery.

The NeurostationTM—A highly accurate, minimally invasive solution to frameless stereotactic neurosurgery

The NeuroStation is an image-guided neurosurgery workstation designed to deliver frameless stereotaxy within an ergonomic, integrated surgical environment. Generally, stereotaxy can provide the neurosurgeon with important intra-operative localization information using diagnostic images such as computerized tomography (CT) or magnetic resonance imaging (MRI). To date, however, stereotaxy has not been widely accepted by neurosurgeons due to the procedural difficulties of incorporating conventional stereotaxy. The NeuroStation addresses the problems of conventional stereotaxy through the use of frameless stereotactic methods wherein state-of-the-art instrumentation and computer innovations allow: a) standard surgical instruments to be used as the localization device; b) multipoint registration methods in place of frame-based registration; and c) real-time interactive surgical localization. The NeuroStation can thus be transparently integrated into the neurosurgical procedure providing the neurosurgeon with image-guidance for surgical planning, biopsies, craniotomies, endoscopy, intra-operative ultrasound, radiation therapy, etc.

Advances in image-directed neurosurgery: preliminary experience with the ISG Viewing Wand compared with the Leksell G frame.

Because of the limited application of frame-based stereotaxy to general neurosurgical procedures, we have carried out a preliminary evaluation of the ISG Viewing Wand, a frameless image-directed surgical system that is based on the rapid reformat and accurate three-dimensional reconstruction capability of parallel processor-based computer technology. We have compared the first 36 cases carried out with the system in the Frenchay Neurosurgery Department with a retrospective analysis of the previous 36 cases carried out using the Leksell G frame. The stereotactic cases were completed over a period of 15 months, representing 2.8% of intracranial procedures. The wand cases were completed in 3 months, 13% of the intracranial practice during that time. The wand was used for 28 supratentorial craniotomies (76%), four infratentorial procedures (11%) and five biopsy procedures (13%). Conventional stereotaxy was not used for posterior fossa or skull base procedures. Supratentorial craniotomy was carried out in nine cases (25%), while the remaining 27 cases involved point source localization within the cranium (75%). The mean preparation time prior to surgery was 65 min for the stereotactic cases and 37 min for the wand cases. We therefore conclude that the indications for frame-based stereotaxy and Viewing Wand use are mutually exclusive. Leksell stereotaxy remains the method of choice for point source localization deep within the cranium. All other procedures requiring an image-directed minimally invasive surgical approach are more appropriately carried out using the Viewing Wand. The system has potential immediate application in supratentorial, skull base and infratentorial tumour surgery, vascular surgery, epilepsy surgery and upper cervical spine surgery.

Ultrasound-guided periventricular stereotaxis.

Intraoperative ultrasound can aid the biopsy of deep intracranial lesions. It is, perhaps, less clear whether ultrasound could be useful in functional neurosurgery, where the target is not abnormal in echogenicity. As an example, we chose to investigate in a dog model the periventricular gray target, which is frequently the choice for the placement of electrodes to control intractable pain. Autopsies showed the placement of our electrodes with less than 1 mm of error in four of five brains and a 1.5-mm error in the fifth brain. The largest error was seen to occur on the video screen and was due to our failure to tighten the guide properly. The potential advantages of this technique over conventional stereotaxis include the avoidance of: ventricular catheterization, the injection of contrast agent into the ventricles, the necessity for a stereotactic frame, and multiple x-ray exposures. Also, with real time scanning the surgeon has instant visual confirmation of electrode placement and can observe quickly any significant hematoma formation.

Stereotactic neurosurgery using 3-D image data from computed tomography.

During the last decade computer tomography (CT) scanners have provided images that show internal anatomy of unsurpassed resolution and that, since they are inherently digital, a format computer graphics software can easily process. By combining CT images, a specially designed head-mounted instrument, and the software to coordinate them, improved surgical accuracy can result for stereotactic surgery. Using the head-mounted frame and the interactive computer software described here, the entire stereotactic approach is transportable to computer systems of three major CT manufacturers. Neurosurgeons now have a tool that allows trajectory selection and probe placement entirely within the CT suite. Compared with conventional stereotaxis, the CT-aided approach offers increased accuracy, with a significant fluid contrast injection for finding reference points and the avoidance of important brain structures due to the direct visualization afforded with CT. Key interactive features are shown here that allow unrestricted views of anatomy in the area of surgical interest. For example, oblique views that are normal to the trajectory of neurosurgical instruments are extracted in real time during the surgical procedure. Standard sagittal (lateral) and coronal (frontal) image planes are also shown integrated with the interactive technique. The surgical procedure is outlined and details of the pattern recognition technique for image-to-frame registration are presented. Test, phantom, and patient results are given.