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PubMed2001

A stereotactic device for experimental rat and mouse irradiation using gamma knife model B--technical note.

BACKGROUND: For radiobiological experiments using the Gamma Knife model B, we constructed a stereotactic device to irradiate rat and mouse brains and verify the absorbed dose at the target using thermoluminescence dosimetry and a head phantom. METHODS: Our stereotactic device is primarily designed for rats using the fixation principles of a stereotactic atlas. A head-fixation adapter for a mouse was constructed to enable targeted irradiation of mouse brains. We built simple phantoms to simulate rat and mouse heads. We placed thermoluminescent dosimeters at various positions on the phantom for dose measurements. Dose planning employed the Leksell Gamma Plan version 4.11 software, assuming a spherical skull geometry for all calculations. FINDINGS: The measurements demonstrated that the actual absorbed dose agreed with our calculations within the errors of thermoluminescence dosimetry and the accuracy of our irradiation technique and dose calculations. INTERPRETATION: This device provides an accurate method for irradiating rat and mouse brains using the Gamma Knife model B.

Animals↗
PubMed2000

A methodology designed to increase accuracy and safety in stereotactic brain surgery.

A series of technical tips and devices designed to increase accuracy and safety in stereotactic surgery are presented. We use stereotactic magnetic resonance imaging with three-dimensional magnetization-prepared rapid gradient-echo (MP-RAGE) imaging to minimize image distortion, and a three-dimensional stereotactic planning system for accurately registering three-dimensional space. We also developed several technical devices useful for stereotactic intracranial procedures; an applicator system attached to the frame which simulates the fiducial markers in order to keep the target at a suitable position in stereotactic space; a torque wrench to set the torque on the fixing pins to the frame reproducibly at 5 inch pounds in order to keep distortion of the frame to a minimum while maintaining secure fixation; an entry point marker to maintain the calculated trajectory angle; a straightening cannula to prevent the thermo-coagulation needle from bending; a microvascular Doppler and its holder to detect significant vessels and to know their precise depth in order to avoid vascular injury from thermocoagulation; a burr hole button device to secure depth electrode cables at the patient's skull.

Brain↗
PubMed1994

Verification of the Schaltenbrand and Wahren stereotactic atlas.

The Schaltenbrand and Wahren stereotactic atlas was critically re-examined focusing on the technical quality and the consistency of the horizontal, sagittal and frontal microscopic cut series. From each series, both an isotropic contour and a solid volume model represented by a 256 matrix with an edge length of 6.4 cm were created using 3D-interpolation. Reslicing of the solid volumes in corresponding orthogonal planes enabled thorough direct comparison of the three series. In a 3D-navigation system prototype, the contour models can be matched to MRI and CT series. Different procedures for rigid matching including landmark matching were implemented. As regards the verification criteria, the frontal Schaltenbrand and Wahren series yielded the most comprehensible results whereas in the horizontal and sagittal series artifacts appear more pronounced.

Brain Mapping↗
PubMed1993

Use of digital mammography in needle localization procedures.

OBJECTIVE: With digital technology, images can be displayed rapidly and manipulated. This study was undertaken to assess the duration and accuracy of needle localizations performed with digital vs film-screen technology. These two technologies also were compared with respect to radiation doses and ability to image a standard phantom. SUBJECTS AND METHODS: A prototype digital mammographic system with both a 512 x 512 matrix and a 1024 x 1024 matrix was evaluated by using the American College of Radiology mammography accreditation phantom, and these results were compared with testing done on commercially available, dedicated, analog mammography equipment. Duration, accuracy of needle placement, and number of exposures needed to perform localization were recorded for 157 consecutive needle localizations done with digital technology, and these results were compared with data collected from 103 needle localizations done with film-screen technology. Another 33 localizations attempted with digital imaging were aborted because of technical factors. Average glandular doses were calculated for those women who had a compressed breast thickness of 4-5 cm. RESULTS: The time to complete needle localization was reduced by almost 50%, from 20 to 11 min, when digital technology was used. Because of the small (5 x 5 cm) field of view of the digital system, an additional mammogram obtained at the onset of the procedure was found to be helpful in localization, but otherwise the number of images was the same regardless of imaging receptor. Mean glandular dose was reduced by about 50% with digital imaging from 0.219 to 0.120 cGy. In those 17% (33/190) of needle localizations that could not be completed with digital imaging, failure was due to a variety of factors. Despite improved detectability of fibrils, specks, and masses on digital images, digital systems did not show some fine calcifications or soft-tissue masses during needle localizations. Difficulty in imaging lesions near the chest wall or in the axilla and the small field of view also caused procedures attempted with digital imaging to be aborted and completed with film-screen systems. CONCLUSION: The time to complete needle localization was reduced by 50%, with a similar reduction in patients' radiation dose, when digital mammography was used. These findings should be applicable to stereotaxic procedures done with digital mammography. Factors limiting the use of digital mammography equipment included inability to image some fine calcifications and some masses, difficulty in imaging near the chest wall and in the axilla, and a small field of view.

Breast Neoplasms↗
PubMed1999

Neuroprotective "agents" in surgery. Secret "agent" man, or common "agent" machine?

The search for clinically-effective neuroprotective agents has received enormous support in recent years--an estimated $200 million by pharmaceutical companies on clinical trials for traumatic brain injury alone. At the same time, the pathophysiology of brain injury has proved increasingly complex, rendering the likelihood of a single agent "magic bullet" even more remote. On the other hand, great progress continues with technology that makes surgery less invasive and less risky. One example is the application of endovascular techniques to treat coronary artery stenosis, where both the invasiveness of sternotomy and the significant neurological complication rate (due to microemboli showering the cerebral vasculature) can be eliminated. In this paper we review aspects of intraoperative neuroprotection both present and future. Explanations for the slow progress on pharmacologic neuroprotection during surgery are presented. Examples of technical advances that have had great impact on neuroprotection during surgery are given both from coronary artery stenosis surgery and from surgery for Parkinson's disease. To date, the progress in neuroprotection resulting from such technical advances is an order of magnitude greater than that resulting from pharmacologic agents used during surgery. The progress over the last 20 years in guidance during surgery (CT and MRI image-guidance) and in surgical access (endoscopic and endovascular techniques) will soon be complemented by advances in our ability to evaluate biological tissue intraoperatively in real-time. As an example of such technology, the NASA Smart Probe project is considered. In the long run (i.e., in 10 years or more), pharmacologic "agents" aimed at the complex pathophysiology of nervous system injury in man will be the key to true intraoperative neuroprotection. In the near term, however, it is more likely that mundane "agents" based on computers, microsensors, and microeffectors will be the major impetus to improved intraoperative neuroprotection.

Coronary Artery Bypass↗
PubMed1997

Differential approach to psychosurgery of obsessive disorders.

One of the most frequent indications of psychosurgical treatment is incurable obsessions. Up to now, capsulotomy or cingulotomy has been preferred. In our opinion, the variety of obsessive conditions require a more thorough approach to the selection of interbrain targets. Forty-seven patients with pure obsessive-compulsive disorders as well as disorders connected with depressions, epileptic syndrome, schizophreniform state and Gilles de la Tourette's syndrome with extremely severe resistance to medical therapy were examined. Eighteen patients were operated on. Surgical treatment is permissible only in cases fulfilling the three following criteria: (1) clinicopsychopathological permissibility (duration of disease, resistance to medication, psychopathological status); (2) physiological permissibility (the presence of a brain target, defining the psychopathological status), and (3) technical permissibility (the availability of proper stereotactic, imaging, electrophysiological and other apparatus necessary to carry out the surgical treatment). One supposes that the outcome of surgical treatment is determined by all three criteria. For the purpose of improving the efficiency of stereotactic treatment, a number of methods of surgical treatment depending on the psychopathological status are suggested. For example, in case of comorbidity of obsession with the epileptiform syndrome, we suggest cingulotomy (capsulotomy) and amygdalotomy; in case of comorbidity with depression we suggest cingulotomy and innominatotomy. The long-term observation of the outcome of stereotactic treatment covers a period from 2 up to 9 years.

Adolescent↗
PubMed1983

Stereotactic neurosurgery and computerized tomographic scanning.

The marriage of computerized tomographic (CT) scanning and stereotactic surgery opens up new technical possibilities, as it becomes feasible to introduce a probe into any lesion which is identified on a CT scan. The various CT stereotactic techniques are reviewed, and generally involve four variations. The head holder of a standard stereotactic apparatus can be adapted to the CT scanner to interdigitate the coordinates of both devices in a known relationship. Second, some types of CT scanners allow the visualization of the vertical coordinate. Third, a stereotactic microdrive can be incorporated into the scanner. Finally, a simple aiming device can be attached to the patient's head and repeated scans taken as the probe is advanced to the target. Various authors have reported the use of techniques for biopsy, aspiration of cysts or hematomas, insertion of radioisotopes, or as an adjunct to open surgery.

Biopsy, Needle↗
PubMed2003

[Comparison and examination of stereotactic surgical complications in movement disorders].

The purpose of the present study was to determine exactly the incidence of surgical complications in patients for whom MRI-targeted, microelectrode recording (MER)-guided implantation of deep brain stimulation (DBS) or radiofrequency (RF)-coagulation surgery was performed. Between January, 1998 and September, 2002, a total of 110 stereotactic surgeries for movement disorders (57 RF-coagulations and 53 implantations of DBS) were performed. We investigated the type and number of complications for each of the following surgical targets; globus pallidus, thalamus, and subthalamic nucleus (STN). Twenty-four neurological complications in 22 patients and 16 radiological/instrumental complications in 16 patients were verified among the 110 surgeries. Among the neurological complications, hemiparesis and mental disturbances were observed at a high rate, while intraoperative hemorrhage frequently occurred among the radiological/instrumental complications. The rate of neurological and radiological/instrumental complications for each of the stereotactic targets; the globus pallidus, thalamus, and STN-targeted surgeries, was 32.4%, 16.7%, 18.8% and 16.2%, 20.0%, 12.5%, respectively. The reason for the high rate of intraoperative hemorrhage may be associated with technical problems resulting from the penetration of vessels by needles, as well as the destruction of small vessels due to heat ablation. As for the mental disturbances, visual hallucinations (VH) occurred a high rate, especially during STN-DBS. Peduncular damage and/or L-dopa toxicity due to STN-DBS may have been associated with VH, so the STN-DBS may therefore be thought to change the threshold of stimulus-induced hallucinations. We also found that the procedures for DBS surgery, especially in younger patients, have a lower risk of complication, while, on the other hand, coagulation surgery for elderly patients is accompanied by of high risks, from the standpoint of surgical complications.

Adult↗
PubMed2005

In touch with robotics: neurosurgery for the future.

The introduction of multiple front-end technologies during the past quarter century has generated an emerging futurism for the discipline of neurological surgery. Driven primarily by synergistic developments in science and engineering, neurosurgery has always managed to harness the potential of the latest technical developments. Robotics represents one such technology. Progress in development of this technology has resulted in new uses for robotic devices in our discipline, which are accompanied by new potential dangers and inherent risks. The recent surge in robot-assisted interventions in other disciplines suggests that this technology may be considered one of a spectrum of frontier technologies poised to fuel the development of neurosurgery and consolidate the era of minimalism. On a more practical level, if the introduction of robotics in neurosurgery proves beneficial, neurosurgeons will need to become facile with this technology and learn to harness its potential so that the best surgical results may be achieved in the least invasive manner. This article reviews the role of robotic technology in the context of neurosurgery.

Equipment Design↗
PubMed1997

Image guided microsurgery with a semifreehand neuronavigational device.

There is only limited experience with neuronavigators among the neurosurgical community so far. We evaluated such a prototype system in order to define indications for its succinct future use and to adjust it to daily clinical practice. We have employed an infrared light-linked computerized system (SPOCS; Aesculap/ISG) for preoperative planning and intraoperative navigation according to digitized images. A wired, penlike sensor-located "pointer" is used for navigation. Forty-eight patients (22 females, 26 males; aged 7-74 years) with a total of 53 intracranial lesions are included in the study. Fourteen lesions were smaller than 2 cm (26.4%), 33 were 2-4 cm (62.3%), and 6 were greater than 4 cm (11.3%). The documented accuracy was in the range of 3 mm or better in 33 patients throughout the whole operation and in an additional 7 through the most important surgical steps, with satisfactory results in all types of patient positioning except for the sitting position. In one patient the accuracy level decreased too early to perform useful intraoperative navigation. Technical dropouts early in the series led to abortion of the navigation in 7 instances but would currently no longer lead to abortion. There was no additional surgical morbidity associated with the use of the system. With more convenience in instrument design and development of techniques for real-time intraoperative reregistration, this kind of navigational device will play an increasingly important role for assistance during intracranial surgery. It proved to be helpful for planning of the craniotomy, intraoperative guidance on occasions of limited exposure and narrow visual field, localization and resection of small lesions in critical areas, and border definition of large lesions and for pure image guided resection of previously marked regions.

Adolescent↗
PubMed1991

The initial experience with the Cosman-Roberts-Wells stereotactic system.

The Cosman-Roberts-Wells stereotactic instrument is a recently developed modification, based on an arc-radius design, of the Brown-Roberts-Wells stereotactic frame utilizing the existing fixation and fiducial components of the Brown-Roberts-Wells stereotactic system to localize and verify target data. The design modification has been made with a view to facilitating technical approaches both in stereotactic biopsy and in stereotactic craniotomy, whilst encompassing the same stereotactic space. Initial experience with the Cosman-Roberts-Wells instrument is reported. Over a 5-month period 55 procedures were performed which included 40 stereotactic biopsies, five CT-guided stereotactic craniotomies, three stereotactic placements of a Bennett Ball for thalamotomy, three stereotactic implantations of intracranial electrodes for recording in drug-resistant epilepsy, three aspirations of cyst or haematoma and one implantation of a Gutin catheter for interstitial brachytherapy. There was minimal morbidity and no mortality related to operation. This frame offers rapid targeting without the need to pre-determine entry points, as well as allowing direct lateral passes and unimpeded stereotactic craniotomy.

Adolescent↗
PubMed1993

Determination of target point magnification rate on stereotactic angiography for radiosurgery--technical note.

We describe here a new method of calculating the target point magnification rate for radiosurgery by stereotactic angiography using a Leksell frame. As the distance (D) between the x-ray focus and the film plane is constant in each facility, the magnification rate (M) is determined by the equation: M = D/[D/Mp + t], where Mp is the magnification rate of the proximal (to the x-ray focus) frame projected on the film plane and t is the distance between the proximal frame plane and the target point. The t value is given by the three-dimensionally determined stereotactic coordinates of the target point. Only the Mp value on the stereotactic angiogram must be measured. This method is theoretically more correct and has less risk of human error than the conventional, graphically determined method which necessitates measuring both the distal and proximal frame magnification rates. Furthermore, the inherent theoretical error of the conventional method is largest around the frame center, which is frequently selected as the target point for radiosurgical treatment, possibly causing serious error in accurate dose planning.

Angiography↗
PubMed1997

Remote stereotactic visualization for image-guided surgery: technical innovation.

Additional data from imaging sources using computer navigation assistance enables virtual visualization of anatomical structures in three dimensions for stereotactic navigation during an operation. Recent developments in communication technology enable the broadcasting not only of video data, but also of stereotactic navigation data via the network. By telepresence/teleconsulting, the composite images and overlapping graphics (instrument, target structure, landmark, contour) can be seen in connected clinics, with the possibility of interactive graphic assistance. In cranio-maxillofacial surgery, the first surgical teleconsultation in real time via telecommunication of stereotactic data was performed in August 1996. A patient suffering from a post-traumatic deformity following multiple comminuted midface fractures was re-osteotomized with the aid of image-guided surgery using teleconsultation: the intraoperative position achieved could be discussed with different surgeons with regard to symmetry, hard/soft tissue relationships and occlusal details, with the possibility of on-screen planning interaction and real time evaluation of the results, over a distance of 500 km.

Computer Graphics↗
PubMed1996

Cerebral arteriovenous malformations: improved nidus demarcation by means of dynamic tagging MR-angiography.

Our purpose was to further improve the target volume definition for radiosurgical treatment of cerebral arteriovenous malformations (AVMs) by means of dynamic MRA (dMRA) using a blood bolus tagging sequence. We therefore compare this technique with 3D-TOF-MRA and transfemoral high resolution angiography in plain film technique. Twenty patients with angiographically proven cerebral AVMs were investigated by dMRA, TOF-MRA, and conventional angiography during the MR-assisted radiosurgical planning protocol. The patient's head was fixed in an MR-compatible stereotactic device. The different angiography techniques were evaluated by consensus of two radiologists. AVMs were characterized by the number and origin of feeding arteries, the maximum diameter of the AVM nidus, and the venous drainage pattern. Dynamic MRA was able to demonstrate the complete AVM characteristics and hemodynamics in 12 out of 20 patients. In three patients with an AVM nidus smaller than 1 cm in diameter the technique could not reliably depict the malformation. Technical problems due to steel screws and pins in the initially used stereotactic frame occurred in five patients. Due to reduced vessel overlap and the lack of disturbances caused by formations with short T1 time, dMRA was superior to TOF-MRA in the detection and the exact localization of the AVM nidus in four patients. We conclude that dMRA is able to demonstrate reliably AVM characteristics and hemodynamics in AVMs with a nidus larger than 1 cm in diameter. Because of the improved demarcation of the AVM nidus, this technique may be a valuable adjunct to radiosurgery planning of cerebral AVMs.

Adult↗
PubMed2004

Stabilization clamp for insertion of deep brain stimulation electrodes: technical note.

BACKGROUND: Deep brain stimulation (DBS) electrodes are being implanted with increasing frequency for the management of movement disorders and chronic pain. Success with this neuro-augmentative technique requires accurate electrode lead placement. In order to enhance accuracy of final lead placement and ease of insertion, we describe a useful and reliable DBS electrode lead stabilization device developed and used at our centre. MATERIALS AND METHODS: The DBS electrode stabilization device consists of a 2-clamp system designed to fit the Leksell stereotactic frame. The clamps work in series to secure the stereotactic lead at the time of its final positioning in the desired subcortical target without the need of fluoroscopic control. RESULTS: The DBS electrode stabilization device has been used in 30 patients for 54 electrode implantations at our institution since 2000. Postoperative magnetic resonance imaging was performed in all cases and confirmed accurate placement of the electrodes. CONCLUSIONS: Accurate electrode lead placement is critical for the clinical efficacy of DBS systems. The simple and reliable stabilization device described here is easy to operate and enhances the final placement accuracy of DBS electrode leads.

Brain↗
PubMed1999

Cerebral microdialysis combined with single-neuron and electroencephalographic recording in neurosurgical patients. Technical note.

Monitoring physiological changes in the brain parenchyma has important applications in the care of neurosurgical patients. A technique is described for measuring extracellular neurochemicals by cerebral microdialysis with simultaneous recording of electroencephalographic (EEG) and single-unit (neuron) activity in selected targets in the human brain. Forty-two patients with medically intractable epilepsy underwent stereotactically guided implantation of a total of 423 intracranial depth electrodes to delineate potentially resectable seizure foci. The electrodes had platinum alloy contacts for EEG recordings and four to nine 40-microm microwires for recording single-unit neuron activity. Eighty-six electrodes also included microdialysis probes introduced via the electrode lumens. During monitoring on the neurosurgical ward, electrophysiological recording and cerebral microdialysis sampling were performed during seizures, cognitive tasks, and sleep-waking cycles. The technique described here could be used in developing novel approaches for evaluation and treatment in a variety of neurological conditions such as head injury, subarachnoid hemorrhage, epilepsy, and movement disorders.

Adolescent↗
PubMed2006

Stereotactic device for Gamma Knife radiosurgery in experimental animals: technical note.

OBJECTIVE: Radiosurgery has become a well-established treatment modality for many intracranial lesions and the information obtained from animal experiments is crucial in devising new strategies with improved efficacy and less risk. We constructed a stereotactic device for rats which can be used for both usual laboratory work and radiosurgery using a Gamma Knife. MATERIALS AND METHODS: The stereotactic device was made by modifying the basic design of the ordinary stereotactic frames used for usual laboratory work. It was developed for both Gamma Knife model B and C. An auxiliary tool was also devised which facilitates the placement of the target point at the radiation isocenter. RESULTS: The reliability of the device was verified by checking the radiation profile and absorbed dose. The results of the experimental irradiation in normal and tumor-cell-inoculated rats demonstrated the usefulness of the device. CONCLUSIONS: The modified animal stereotactic frame described herein can be used for both the production of experimental animal models and for performing radiosurgery with a common apparatus.

Animals↗
PubMedDate not supplied

Image-guided surgery in resection of benign cervicothoracic spinal tumors: a report of two cases.

BACKGROUND CONTEXT: Osseous spinal tumors are an uncommon cause of persistent axial pain and muscle spasm, but even benign lesions may grow to cause deformity or neurological signs. Traditional treatment approaches to resection can be debilitating even when the tumor is benign. PURPOSE: Emerging technologies allow surgeons to diagnose and treat osseous neoplasms while minimizing the collateral damage caused by surgical exposure and tumor excision. STUDY DESIGN: Technical considerations are presented through two cases of benign osseous neoplasm occurring in the cervicothoracic spine of competitive athletes, demonstrating the meth-ods used to provide effective treatment while maintaining maximal functional capacity. METHODS: Stereotactic imaging and intraoperative guidance was used as an adjunct to tumor care in these patients. Used in combination with minimally invasive, microsurgical techniques,stereotactic guidance localized and verified excision margins of benign vertebral lesions, minimizing soft tissue trauma and collateral damage. RESULTS: Computer-assisted stereotactic localization allowed us to successfully ablate these lesions from their anatomically challenging locations, without disrupting the shoulder girdle or neck musculature, and without extensive bony resection. CONCLUSIONS: Image guidance can accurately localize and guide excision of benign vertebral lesions while minimizing soft tissue trauma and collateral damage, allowing patients a rapid and complete return to high-demand function.

Adolescent↗