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STUDY DESIGN: In vitro assessment of accuracy and reliability of frameless stereotaxis for insertion of pedicle screws in human cadaveric lumbar spine. OBJECTIVES: To assess a new method of targeting and placing pedicle screws in a human cadaver study. SUMMARY OF BACKGROUND DATA: Pedicle screw instrumentation is common. Complications may occur from improper placement of screws. Even when performed by experienced spinal surgeons, improper placement can occur in 5.2% of pedicles instrumented. Development of computer-guided methods of pedicle screw insertion may decrease this complication rate. METHODS: The technique used preoperative computed tomography scans together with a commercial neurosurgical navigational computer system to assist in placing guidewires in the pedicles. A section of human cadaver spine was first scanned and the data transferred to the workstation. The image data set and physical specimen were then registered by using an instrumented articulated arm to identify selected points on the specimen and randomly sample surface points. Eight highly repeatable locations on each vertebral body were found to be suitable for registration, but better overall accuracy was obtained when surface matching was used in combination with these points. Under guidance of image on the computer, Kirschner wires were inserted into the pedicles of four vertebral bodies. The spine was rescanned, and the planned and resulting positions of the wires compared. RESULTS: The average distance between the planned and resulting wire entry point was 1.2 mm, with an average difference in planned and resulting trajectories of 6.0 degrees. CONCLUSIONS: Computer-aided pedicle screw instrumentation is feasible. Further technical points require clarification before widespread use is possible.
Arachnoid cysts are well known to the neurosurgeon, and the evolution of their surgical treatment has followed technological advances in neurosurgical procedures and techniques. With the recent mastering of neuroendoscopy by the neurosurgeons, it is becoming the modality of choice for the treatment of arachnoid cysts. A neonate harboring a middle parasagittal arachnoid cyst benefited from stereotactically guided endoscopy. We report this case because of its peculiarities and introduce technical details about the procedure which are not found in the literature.
Teletherapy of nonresectable radiosensitive brain tumors is the mainstay of adjunctive treatment. In the past two decades brachytherapy has begun to play an ever-increasing role, particularly on the European continent. Yet this attention has been addressed almost exclusively to lesions of the supratentorial space. This article describes modifications of the Riechert-Mundinger stereotactic system which were made by one of us (P.D.) to allow an unencumbered yet precisely computerized stereotactic approach to posterior fossa lesions for biopsy and interstitial radiation with iridium 192. A case report is described to illustrate the technical details involved in such an undertaking.
The application of stereotactic techniques to the spinal cord as a logical sequel to percutaneous procedures have produced significant developments by enabling the functional exploration of different cord structures. Radiofrequency lesions were placed either at the spinal trigeminal nucleus, for facial pain of central origin such as postherpetic neuralgia or anesthesia dolorosa as well as for neoplastic pain of extensive craniofacial distribution, or at the central cord region to interrupt preferentially multisynaptic nonspecific pathways mainly for midline and/or bilateral pain but also for patients with respiratory inadequacy or for certain central pain states. Technical aspects are reported, and physiological correlates relevant to surgery are analyzed. Results, indications and limitations are discussed.
This report will evaluate the feasibility of applying image-directed robotic technology to the field of otolaryngologic surgery. Image-directed robotic surgery uses a three-dimensional image to guide a robot in the removal of tissue. To demonstrate the future use of image-directed robotics in otolaryngologic surgery, five antrostomies will be performed on temporal bones. The accuracy of the surgical defect will be measured. It is the goal of this pilot study to achieve an average surgical error of less than 1.0 mm. Future applications of image-directed robotic surgery will be presented, along with technical modifications, and future areas of research necessary to adapt this technique to otology and rhinosinus surgery.
Endoscopic transnasal approach has become a procedure of choice for the surgical management of pituitary lesions. However, in conventional endoscopic transnasal surgery, the surgeon may become disorientated to the actual operating position. In our series, 47 patients have undergone an endoscopic transnasal approach to the pituitary with the use of the navigation system called InstaTrak for real-time imaging. This image guidance system proved valuable for anatomical localization during pituitary surgery. We have reduced the average surgical time, and improved patient outcome. As a consequence, complications during surgery should decrease and safety should increase. Intra-operative image guidance is expected to have major advantageous effects on pituitary surgery by allowing the surgeon to remove lesions more efficiently. As this system is improved technically and surgeons become more proficient in their use, there should be better postoperative outcomes.
Convex, parasagittal, and falcine meningiomas represent a group of tumors that naturally fall together in terms of symptoms, surgical technique, and potential problems related to their anterior-posterior location. There are significant differences in the technical aspects of the surgical approaches to these three supratentorial meningiomas, which are reviewed separately in this article.
PURPOSE: To assess magnification error in digital subtraction angiography as it pertains to arteriovenous malformation (AVM) size. METHODS: A rectangular grid phantom with equally spaced markers mounted in a stereotactic frame was imaged with digital angiographic equipment. The location and orientation of the grid was altered relative to the central plane of the phantom. Both linear and area measurements were made according to the perceived location of phantom markers using a standard catheter calibration technique and compared with stereotactically derived estimates. Finally, a single case example of an angiographically imaged rolandic AVM was used to compare linear dimensions obtained with both described techniques. RESULTS: The determination of location and size with standard angiographic imaging is subject to error because of the divergent geometry of the incident x-ray beam. The resulting nonconstant geometric magnification causes errors in linear measurements of 10% to 13% at depths of 7 cm from the calibration plane. Errors in area measurements at the same position increase by 20% to 25%. Measurements of maximum diameter or cross-sectional area may have an additional error when nonspherical objects are inclined to the viewing direction (40% at 45 degrees inclination). These errors are reduced to less than 1 mm using the stereotactic technique. Some commercial angiographic systems have internal software to enable a spatial calibration based on known distances in the image or on the diameter of a catheter. The catheter technique was accurate in the calibration direction (perpendicular to the catheter axis) but had a 12% error in the direction parallel to the catheter because of a nonunity aspect ratio in the video system. Measurement of the dimensions of a rolandic AVM using the catheter calibration technique had an error that ranged from -3% to +26% (standard error, 20%) with respect to the stereotactic technique. CONCLUSIONS: Numerous nonstereotactic referential systems for determining linear distances are inherently erroneous by varying degrees compared with the stereotactic technique. Area and volume determinations naturally increase this error further. To the extent that no standardized method for determining linear distances exists, significant variations in estimation of AVM size result. Classification schemes for AVMs have been hampered by this technical error.
A simple technique for marking functional neurosurgery target on computed tomography (CT) axial image is described. This permits the use of standard axial image for computed tomography (CT) stereotaxis in functional neurosurgery.
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PURPOSE: Evaluation of an interactive, stereotactic biopsy device integrated in an open superconductive 0.5 tesla MR-scanner with a vertical gap. MATERIAL AND METHODS: In addition to "in-vitro" experiments performed on a plexiglas phantom with holes of varying diameters (5-20 mm) biopsies on eleven patients (7 women, 4 men; average age 55 years) were performed in the interventional MR-system. Lesions in the abdomen (n = 6), muscle (n = 1), thyroid (n = 3) and breast (n = 1) were targeted with 18-20 G aspiration biopsy needles of 5-15 cm length. The intervention was interactively guided by a fast T1-weighted 2-D gradient echo sequence. RESULTS: All of the 15 and 20 mm holes of the phantom, but only 83% of the 10 and 5 mm holes were hit. No complications occurred during the MR-guided patient procedures. All lesions (mean size 3.5 cm, distance from the skin 2 cm to 10 cm) were biopsied successfully. The fast image acquisition in combination with the stereotactic technique enables interactive control of the needle. CONCLUSIONS: Stereotactic, interactively controlled biopsies in the interventional MR are technical feasible. However, the range of meaningful indications for MR-guided biopsies is limited.
The outcomes of stereotactic biopsy (STB) of pineal tumors are presented. This diagnostic approach was applied in 51 patients aged 7 to 59 years (mean 23 years) and its main indication is to develop an adequate treatment policy by specifying the histological structure of a tumor. Informative morphological samples were taken in 42 (82%) cases. One patient died, another developed a persistent neurological defect after STB. A third of all cases was diagnosed as having germinomas and other 5 patients were found to have germinative cellular tumors of mixed structure, which reflects the views on the policy of examination and treatment of patients with pineal tumors and indications for the biopsy, which have been established at the N. N. Burdenko Institute of Neurosurgery, Russian Academy of Medical Sciences. In 14 cases, STB diagnosis was verified from 1 to 46 weeks of postbioptic surgery connected with tumor removal or autopsy. There was 100% coincidence in histological diagnosis. Indications for STB in patients with pineal tumors, the significance of its findings, methodological and technical aspects, as well as the clinical value of this diagnostic procedure are dealt with in the paper.
The first biopsy in Val-de-Grâce has been performed in 1987, under CT alone, with a Leksell frame. 150 punctures have been performed for a diagnostic or a therapeutic goal. Since 1990, stereotaxy is performed under MRI. 320 punctures have been made with 1.9% mortality and 1.3% morbidity. The future of stereotactic technics is therapeutic: precision of surgery (vascular malformation, neurogenous tumor, deep tumor), precision of radiotherapy, new anti-tumoral treatments.
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A new technique for deep-brain electrode implantation is described. A very flexible nontraumatic electrode guided by a central stylet and a new electrode head-fixation screw are the two unique features of this system. Electrodes can be guided precisely and their watertight fixation to the bone by means of the special screw is reliable and totally reversible. The system has been designed to fit most of the stereotaxic frames currently in use.
STUDY DESIGN: Endoscopic spinal procedures were performed under computed-tomography-based, image-guided assistance. OBJECTIVE: To assess the clinical feasibility of applying a methodology that allows image-guided assistance in endoscopic spinal surgery. SUMMARY OF BACKGROUND DATA: Endoscopic spinal procedures have become a part of the minimal invasive approaches to the spine. The main disadvantage of these techniques is the long learning curve and the lack of peroperative monitoring. Fluoroscopy does have disadvantages, such as positioning during surgery and the risk for radiation exposure. Fluoroscopy-based navigation has many advantages, however it is still based on preselected fluoroscopic images. There is no method that allows computed-tomography-based navigation in endoscopic conditions. METHODS: Two patients have been operated on using endoscopic approaches assisted by computed-tomography-based navigational system. One had a thoracoscopic approach for median calcified disc herniation and another one had an endoscopic posterior approach for resection of a sacro-iliac osteophyte. For each patient, a frame of reference had been placed percutaneously and scanned. The computed tomography images were registered to the anatomy using the geometry of the frame as fiducials. Navigation through endoscopic approaches was possible in both cases. RESULTS: In both cases navigation was reliable and a helpful monitoring to achieve the surgical goals through endoscopic approaches. CONCLUSIONS: There are some factors that make endoscopic spine surgery a difficult start. Image-guided spine surgery is technically feasible and clinically applicable in endoscopic approaches.
We describe our experience with stereotactic microsurgical resection of 27 lesions using the Leksell frame in 23 patients; 7 had cerebral metastases, 6 had gliomas, 6 had vascular malformations, 3 had meningiomas and 1 had radiation necrosis. Gross total removal of the lesion was accomplished in every case. All lesions were between 1.0 and 3.5 cm in greatest diameter and located either deep within the cerebral (n = 7) or superficially in areas of functional cortex (n = 20). There was no operative mortality and only minimal morbidity. Average length of operating time including frame application, imaging and resection was 4.4 h and most patients were discharged on the second postoperative day. The indications, advantages and limitations of stereotactic craniotomy are discussed and technical modifications that extend the usefulness and safety of this technique are described.