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PubMed1987

[Value and technic of translating the data from x-ray computed tomography into the stereotaxic coordinates of the Talairach system].

The neuroradiological stereotactic examinations provide indispensable information to localize many intracranial lesions: the data obtained by the CT-Scan are complementary of the stereotactic ones. The transfer of the routine CT-Scan transverse axial slices into the Talairach stereotactic system needs a precise definition of the inclination of the plan of the slices and a correct evaluation of the mean magnification factor. The inclination of the slices is appreciated using the bony, vascular and ventricular landmarks clearly identified on the CT-Scan and stereoscopic stereotactic images. We compared the spatial "reconstructed" CT-Scan data with the histopathological findings obtained by serial stereotactic biopsies in 48 tumor patients. The error varied from 1.5 to 4.6% (m: 2.7 +/- 1.2) on the sagittal plane; from 1.3 to 10% (m: 5.8 +/- 3.4) on the transversal plane; from 2.5 to 4.3% (m: 3.5 +/- 0.7) on the axial plane. The mean global error was 3.7% +/- 2.3. The CT-Scan directly performed under stereotactic conditions (acrylic frame) seems to be the more useful procedure. Nevertheless considering the good precision obtained with our methodology applied to the Talairach's system, we consider it suitable when: a) the gantry of the CT-Scan apparatus is too narrow for the acrylic frame; b) the exploitation of previous CT-Scan examinations is necessary; c) patient refuses the discomfort of the acrylic frame.

Brain Diseases↗
PubMed1986

[Application of the Talairach stereotaxic system for the purpose of establishing a common reference plane for brain imaging technics (CAT scan, NMRI, PET scan)].

Confrontation of data obtained from several modern imaging techniques (CAT Scan, NMR Scan, PET Scan) is a fundamental problem in actual neurological practice and must be correlated with histology. For that purpose, we use the referential plane of the stereotactic Talairach frame. Using teflon intraosseous buttons, the referential plane and a common zero reference point can be objectivated by CAT, NMR and/or PET Scans. A computer program gives the exact coordinates of the chosen target. These coordinates are immediately usable in the operating room for stereotactic serial biopsies.

Brain↗
PubMed1985

Interstitial radiation for treatment of primary brain tumors using the Brown-Roberts-Wells stereotaxic system.

While techniques and practice of stereotaxic surgery have been available for decades, recent technical and theoretical advances have allowed for a rebirth of this neurosurgical subspecialty. One of the newer applications of this technique is the stereotaxic treatment of malignant brain tumors. This method depends on the CT-guided placement of a tiny coaxial catheter system precisely on target within the tumor area. Radioactive sources in the catheter deliver a precise amount of radiation over a specific time course. The system is then removed. Follow-up of the patients who undergo this procedure continues throughout their lives.

Brachytherapy↗
PubMed2005

Accuracy of stereotaxic positioning of transcranial magnetic stimulation.

In cognitive neuroscience, optically tracked frameless stereotaxic navigation has been successfully used to precisely guide transcranial magnetic stimulation (TMS) to desired cortical areas for brain-mapping purposes. Thereby, potential sources of imprecision are the fixation of a reference frame to the head of the subject and the referencing procedure according to certain landmarks (LM). The aim of our study was to evaluate the accuracy of frameless stereotaxic coil positioning in a standard experimental setting. A parameter for accuracy is the reproducibility of LM coordinates. In order to test the stability of the referencing for stereotaxic positioning within a single TMS session (within-session stability), the coordinates of six predefined facial LM in nine subjects were recorded first after the initial registration and second after a 20 minutes TMS session. The two sets of coordinates were then compared. The reliability of the positioning coordinates between different TMS sessions (inter-session repeatability) was addressed by registering the subjects LM coordinates in two independent TMS sessions. The variance of the recorded coordinates was analyzed. Altogether, LM were registered 1728 times (192 measures per subject). Within-session stability: The mean Euclidean distance (MED) between the LM position coordinates before and after a TMS session was 1.6 mm, when pooling over all LM. Inter-session repeatability: The MED between the LM positions recorded after the reference procedures of two different sessions showed an average deviation of 2.5 mm. In conclusion, optically tracked frameless stereotaxic coil positioning is from the technical viewpoint of high stability and repeatability. It is therefore a precise method for TMS brain mapping studies or for repeated TMS treatments, with the need of topographically exact stimulation.

Adult↗
PubMed2000

Stereotaxic core needle biopsy of breast microcalcifications obtained using a standard mammography table with an add-on unit.

OBJECTIVE: To demonstrate the reliability of stereotaxic biopsy of indeterminate microcalcifications using a standard mammography table with an add-on unit. METHODS: In 121 cases of indeterminate microcalcifications, core biopsy was performed using a standard mammography table with an add-on stereotaxic unit. Microcalcifications were identified on radiography of core specimens. RESULTS: Microcalcifications and a definitive histologic diagnosis were obtained in 112 core biopsies (92.6%), with no significant complications. In 23 lesions frank malignancy was diagnosed, and all of these diagnoses were confirmed on surgery. Pathologic examination suggested carcinoma in 4 lesions, and open biopsy confirmed malignancy in 3 of these cases. Four lesions showed atypical ductal hyperplasia. Benign disease was diagnosed in 81 lesions, of which 78 remained stable on mammographic follow-up (mean 16 months later) and 3 were subjected to surgical biopsy (of which 1 was malignant and 2 were benign). Nine cases were technically unsatisfactory because microcalcifications were not sampled. CONCLUSION: Stereotaxic core biopsy performed with an add-on unit is a safe and reliable technique for biopsy of indeterminate microcalcifications. For successful biopsy, microcalcifications must be harvested. Pathologic results should be correlated with mammographic findings. The accuracy rate compares favourably with results reported using prone biopsy tables. In an era of cost containment, this alternative to prone biopsy tables could result in significant savings in terms of capital investment and use of hospital rooms. In this study, surgical biopsy could have been avoided in 64.5% of cases.

Adult↗
PubMed2006

Simple technique of head fixation for image-guided neurosurgery in infants.

INTRODUCTION: The authors describe an extremely simple technique of head fixation for image-guided neurosurgery in young children in whom standard pin fixation cannot be used. MATERIALS AND METHODS: This involves positioning the head on a horseshoe headrest and using a 'U-drape' to fix the head to the headrest. RESULT: Over the last 5 years, this technique of head fixation (in conjunction with Stealthstation) has been used for various neurosurgical procedures in more than ten infants successfully.

Brain Diseases↗
PubMed1998

Cardiovascular responses to microinjections of glutamate into the nucleus tractus solitarii of unanesthetized supracollicular decerebrate rats.

In anesthetized rats, microinjections of excitatory amino acids (EAAs) into the nucleus tractus solitarii (nTS), in a region located immediately rostral to the calamus scriptorius (CS), have been generally reported to elicit depressor and bradycardic responses. On the other hand, in conscious freely moving rats, similar microinjections have been reported to elicit pressor and bradycardic responses. These divergent results have been attributed to the effect of anesthetics. A reinvestigation of the effects of EAAs into the nTS in unanesthetized animals became necessary in order to resolve this controversy. The microinjection technique used in freely moving conscious rats suffers from several technical limitations; for example, microinjections cannot be delivered stereotaxically. In order to avoid these limitations, the present experiments were carried out in unanesthetized supracollicular decerebrate rats. A systematic mapping of nTS in these rats, using microinjections of the solutions of EAAs in artificial cerebrospinal (aCSF) fluid, confirmed that depressor and bradycardic responses are elicited from all the sites in the nTS extending from the CS to a level about 1 mm rostral to it. Pressor responses were elicited by microinjections of l-glutamate (l-Glu) only from the chemoreceptor projection site (a region of the commissural subnucleus, 0.1-0.5 mm caudal to the CS, 0-0.5 mm lateral to the midline and 0.4-0.5 mm deep from the medullary surface). The pressor responses elicited from the aforementioned site were accompanied with bradycardia; this response may be due to diffusion of l-Glu to the dorsal motor nucleus of vagus because the bradycardia disappeared when the depth of the microinjection was reduced to 0.3, instead of 0.5 mm, from the dorsal medullary surface. When urethane was administered intravenously in unanesthetized decerebrate rats, the responses to microinjections of l-Glu remained unchanged, i.e., depressor and bradycardic responses were elicited from all the sites in the nTS extending from the CS to a level about 1 mm rostral to it and pressor and tachycardic responses were elicited from the chemoreceptor projection site. These observations indicated that there is no anesthetic-induced qualitative alteration of the cardiovascular responses to microinjections of EAAs into the nTS.

Anatomy, Cross-Sectional↗
PubMed1981

Stereotaxic reconstruction of the aqueduct of Sylvius.

A stereotaxic technique has been developed to cannulate the cerebral aqueduct in patients with hydrocephalus resulting from occlusion of the aqueduct of Sylvius. Precise placement of a 15- to 20-mm long radiopaque prosthesis between the third and fourth ventricles can reestablish the normal cerebrospinal fluid (CSF) pathway. Since 1974, seven patients have undergone aqueductal reconstruction. The surgical goal in this series was to manage the hydrocephalus by creating and maintaining a patent aqueductal channel. The follow-up period ranged from 1.5 to 6.5 years. In four cases, aqueductal reconstruction alone resulted in control of the hydrocephalus, although two patients underwent revisions of their prosthesis. Three patients ultimately required shunts, despite initial symptomatic improvement after reconstruction. In these seven cases (13 stereotaxic procedures), no mortality and no significant operative morbidity were encountered. Although the technique is relatively simple to perform, technical difficulties remain. At present, no clinical or radiographic test adequately discerns the ideal candidate for stereotaxic aqueductal reconstruction. Four patients required stereotaxic revision because of malposition or malfunction of the prosthesis. This approach should be reserved for patients with a short aqueductal occlusion, and normal distal CSF pathways and dynamics. The rationale, technique, problems, and results of stereotaxic reconstruction are presented.

Adolescent↗
PubMed1996

Prolonged persistence of substantial volumes of potentially viable brain tissue after stroke: a correlative PET-CT study with voxel-based data analysis.

BACKGROUND AND PURPOSE: The existence in humans of brain tissue at risk for infarction but potentially viable (eg, the penumbra) remains unproven. One retrospective operational definition of such tissue includes its final infarction despite a relatively preserved or even normal cerebral metabolic rate of oxygen (CMRO2) in the early hours after stroke onset. Although previous positron emission tomography (PET) studies identified tissue whose CMRO2 declined from the acute to the subacute stage, in principle compatible with deteriorating penumbra, they all lacked a coregistered CT scan mapping of final infarct and an objective three-dimensional PET data analysis, while many patients were studied in the subacute (up to 48 hours) phase. We have evaluated whether tissue with CMRO2 ranging above a threshold for presumably irreversible damage in the first 18 hours of middle cerebral artery territory stroke, but below it in the chronic stage, could be retrospectively identified within the final infarct volume. METHODS: Our data bank comprises 30 consecutive patients with first-ever middle cerebral artery territory stroke prospectively studied with PET within the first 18 hours after clinical onset; the 15O equilibrium method was used to measure cerebral blood flow and CMRO2. All survivors with the following criteria were eligible for the present study: (1) technically adequate chronic-stage PET performed in the same stereotaxic conditions, (2) coregistered CT scan also performed in the chronic stage, and (3) an infarct of sufficient dimension (>16mm diameter) on late CT. Corresponding CT scan cuts and PET slices were exactly realigned, and the outlines of CT hypodensities were superimposed on the corresponding CMRO2 matrix. Infarcted voxels with CMRO2 values less than or greater than 1.40 mL/100 mL per minute (ie, the generally accepted threshold for irreversible damage) were automatically identified and projected on matrices of all other PET parameters and for both PET studies. RESULTS: Eight patients (mean age, 78 Years) were eligible for the present study. The acute-stage PET study was performed 7 to 17 hours after stroke onset and the chronic-stage PET 13 to 41 days later. Within the final infarct, mean CMRO2 fell significantly from the acute- to the chronic-stage PET study (P<.001). Eventually infarcted voxels with acute-stage CMRO2 values above the threshold were found in each of these eight patients; they were most often situated near the infarct borders and constituted 10% to 52% (mean, 32%) of the final infarct volume. The acute-stage CMRO2 in these voxels ranged up to 4.13 mL/100 mL per minute but fell below 1.40 mL/100 mL per minute in 93% of them at the chronic-stage PET. in 7 of 8 patients the acute-stage mean cerebral blood flow ranged from 10 to 22 mL/100 mL per minute, and the mean oxygen extraction fraction was markedly increased (>0.70) in these voxels, consistent with a penumbral state. CONCLUSION: In a strictly homogeneous sample of prospectively studied patients, we have identified, up to 17 hours after stroke onset, substantial volumes of tissue with CMRO2 well above the assumed threshold for viability that nevertheless spontaneously evolved toward necrosis. This tissue exhibited penumbral ranges of both cerebral blood flow and oxygen extraction fraction and thus could represent the part of penumbra that might be saved with appropriate therapy.

Aged↗
PubMed1994

Halo ring supporting the Brown-Roberts-Wells stereotactic frame for fractionated radiotherapy.

The authors describe a new instrumentation for repositioning of the Brown-Roberts-Wells (BRW) stereotaxic system, useful for precise fractionated radiotherapy. A lucite ring is fixed to the patient's skull with four screws. Another ring, partially open, is then firmly connected co-axially to the lower part of the first one with four spacer-bars. The fixture permits an exact repositioning of the B.R.W. stereotaxic system, placing the target point in the linear accelerator isocenter. The preliminary technical results obtained in five children are reported and the fixture performance, advantages, and perspectives are discussed.

Brain Neoplasms↗
PubMed2005

Seven years of clinical experience with teleconsultation in craniomaxillofacial surgery.

PURPOSE: In this work the experiences from 50 telemedically supported treatments in craniomaxillofacial surgery are summarized and different setups for their technical realization are described. Furthermore, for the first time the innovative UMTS (universal mobile telecommunication system) is applied for the transmission of arthroscopic videos of the temporomandibular joint and other craniomaxillofacial structures. MATERIALS AND METHODS: The combination of computer-assisted navigation technology in augmented reality environments with telecommunication is used for execution of interactive stereotaxic teleconsultation. Furthermore, treatments without navigation are telemedically supported. This study is composed of 4 technical system configurations: 1) integrated services digital network (ISDN)-based videoconferencing without remote control of the navigation computer; 2) transmission control protocol/internet protocol (TCP/IP)-based interactive teleconsultation via bundled ISDN lines (including remote control of the navigation computer); 3) TCP/IP-based interactive teleconsultation via network; 4) combination of TCP/IP-connection and ISDN-based videoconferencing. The telemedically supported treatments are: orbitozygomatic osteotomies, positioning of the mandibular condyle in orthognathic surgery, insertion of implants, positioning of the maxilla in orthognathic surgery, distraction osteogenesis, arthroscopies of the temporomandibular joint, and operation simulations on stereolithographic models. The surgical interventions are evaluated on a 5-level system performance scale from the technical point of view. In a separate trial 20 videosequences of arthroscopies of the temporomandibular joint are transmitted via UMTS cellular phones and independently evaluated by 3 experts (ie, a total of 60 streamings) to investigate feasibility of this technology in the field of craniomaxillofacial surgery. RESULTS: In the years from 1996 to 2002 a total of 50 treatments were telemedically supported. All intraoperative applications were successfully finished; 48 of 60 UMTS transmissions were finished without any interruptions in constant quality, slight interruptions were observed in 8 tests, and a complete breakdown was observed during 4 streamings that required a restart of the transmission. Resolution was sufficient to diagnose even tiny anatomic structures inside the temporomandibular joint, but orientation was hardly recognizable. CONCLUSION: In many applications telecommunication technology can contribute to a quality improvement in cranio- and maxillofacial surgery because of the global availability of specialized knowledge. The required technical expenditure for teleconsultation crucially depends on the infrastructure that is already available at the clinic and the remote site. UMTS is a promising technology with the potential to be valuable in numerous craniomaxillofacial applications.

Arthroscopy↗
PubMed1982

a 10-year experience in the treatment of trigeminal neuralgia. Comparison of percutaneous stereotaxic rhizotomy and posterior fossa exploration.

Of 1000 patients with classic trigeminal neuralgia who were treated during the last 10 years, 90% had an initial favorable response to medical therapy, but 75% (750 patients) failed to achieve satisfactory long-term relief. Of these, 700 patients were treated by percutaneous stereotaxic rhizotomy (PSR) and 50 were selected for posterior fossa exploration (PFE). Of the 50 patients undergoing PFE, 82% had neurovascular contact at the trigeminal root entry zone, but only 46% were judged to have had significant neurovascular compression. Exploration was negative in 16% of patients and revealed neural compression by bone in 2%. Patients with neurovascular compression were treated by microvascular decompression (MVD); all other patients with exploratory surgery underwent partial sensory rhizotomy. At 3 years after PFE, 84% of patients are pain-free. Results are excellent in 68%, good in 12%, fair in 4%; 12% had a recurrence of their neuralgia. The 700 patients treated by P SR have been followed for 6 years. Results area excellent in 61%, good in 13%, fair in 5%, and poor in 1%; 20% had a recurrence. This study indicates that there is no significant difference in results between PSR and PFE in the treatment of trigeminal neuralgia. The concept that neurovascular compression is a mechanical factor in the etiology of trigeminal neuralgia was supported, but neurovascular compression was less common than previously reported. Percutaneous stereotaxic rhizotomy is a less formidable procedure than PFE, and is easily repeated. Recent technical advances have improved the results obtained with PSR. Therefore, PSR remains the procedure of choice for the majority of patients with trigeminal neuralgia.

Cranial Fossa, Posterior↗