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At least 505 records · Page 28Linked to original sources
PubMed2003

Stereotactic biopsies of focal brainstem lesions.

BACKGROUND: Stereotactic biopsies of the brainstem (SBB) are a selected group of stereotactic operations owing to the lower incidence of brainstem lesions requiring biopsy, the greater complexity, and the higher risks of these procedures. Usually, the lower the lesion in the brainstem, the greater the risks involved. The approach of the different target locations by distinct routes, transcerebral and transcerebellar, is still a matter of debate. Moreover, pure medullary lesions are seldom biopsied, whereas diffuse brainstem lesions, typical of children's brainstem gliomas and rather frequent in most published series, depend less and less on the histopathological confirmation for treatment. In this study, the authors present their own experience on SBB aiming to discuss mainly their indications, approach routes choice, and procedure techniques. METHODS: The authors reviewed a series of 30 SBB (27 adults and 3 children) out of 450 stereotactic biopsies of the central nervous system performed for the last 10 years. All cases but one presented as focal brainstem masses, 19 mainly in the pons and 10 in the midbrain. Eleven lesions (10 in the midbrain and one midbrain-pontine) were approached by a transfrontal route. All the others were approached by a suboccipital transcerebellar route. RESULTS: Twenty-six (87%) out of the 28 cases (93%) where a positive histopathological result was obtained had a specific diagnosis: 18 tumors (14 astrocytomas, 2 primary brain lymphomas, 1 oligodendroglioma, and 1 ganglioglioma), 2 toxoplasmosis, 2 sarcoidosis, 1 aspergillus abscess, 1 vasculitis, 1 acute inflammatory demyelinating disease, and 1 progressive multifocal leucoencephalopathy. Four nontumoral lesions arose in patients with AIDS. Morbidity was restricted to 2 cases consisting of transient cranial nerve deficits. CONCLUSIONS: Stereotactic biopsies are specially useful for the diagnosis of focal brainstem lesions. Midbrain and midline lesions should be approached through the cerebrum, whereas most of the pontine lesions through the cerebellum. Overall, this procedure should be performed with "functional-like" precision and require some technical refinements to reach maximal accuracy with minimal morbidity.

Adolescent↗
PubMed2001

A linac-based stereotactic irradiation technique of uveal melanoma.

PURPOSE: To describe a stereotactic irradiation technique for uveal melanomas performed at a linac, based on a non-invasive eye fixation and eye monitoring system. METHODS: For eye immobilization a light source system is integrated in a standard stereotactic mask system in front of the healthy eye: During treatment preparation (computed tomography/magnetic resonance imaging) as well as for treatment delivery, patients are instructed to gaze at the fixation light source. A mini-video camera monitors the pupil center position of the diseased eye. For treatment planning and beam delivery standard stereotactic radiotherapy equipment is used. If the pupil center deviation from a predefined 'zero-position' exceeds 1 mm (for more than 2 s), treatment delivery is interrupted. Between 1996 and 1999 60 patients with uveal melanomas, where (i) tumor height exceeded 7 mm, or (ii) tumor height was more than 3 mm, and the central tumor distance to the optic disc and/or the macula was less than 3 mm, have been treated. A total dose of 60 or 70 Gy has been given in 5 fractions within 10 days. RESULTS: The repositioning accuracy in the mask system is 0.47+/-0.36 mm in rostral-occipital direction, 0.75+/-0.52 mm laterally, and 1.12+/-0.96 mm in vertical direction. An eye movement analysis performed for 23 patients shows a pupil center deviation from the 'zero' position<1 mm in 91% of all cases investigated. In a theoretical analysis, pupil center deviations are correlated with GTV 'movements'. For a pupil center deviation of 1 mm (rotation of the globe of 5 degrees ) the GTV is still encompassed by the 80% isodose in 94%. CONCLUSION: For treatments of uveal melanomas, linac-based stereotactic radiotherapy combined with a non-invasive eye immobilization and monitoring system represents a feasible, accurate and reproducible method. Besides considerable technical requirements, the complexity of the treatment technique demands an interdisciplinary team continuously dedicated to this task.

Eye Movements↗
PubMed1992

Tumour resection by stereotactic laser endoscopy.

Recent advances in neuro-imaging have led to the early diagnosis of increasingly smaller and more deeply-seated tumours. Conventional neurosurgical techniques are often not satisfactory to deal with these lesions. The authors describe their preliminary experience with a prototype neuro-endoscope. The technical characteristics of the instrument and description of its use in performing stereotactic laser tumour resection are provided.

Brain Neoplasms↗
PubMed2001

Secondary tumor formation after stereotactic biopsy for intracerebral metastatic disease.

BACKGROUND: There are only a few published cases of iatrogenic tumor seeding and distant neoplastic growth along the path of the cannula after stereotactic biopsy. CASE DESCRIPTION: We report the case of a female patient with a solitary lung cancer metastasis in the left parietal brain lobe. The tumor was stereotactically biopsied and treated by radiosurgery. One month after the initial biopsy, a smaller de novo tumor mass located along the track of the stereotactic cannula was detected by contrast-enhanced MRI. The spatial location of this neoplastic nodule and the short time before development of a macroscopic lesion seemed to confirm iatrogenic tumor cell spread due to the stereotactic procedure. CONCLUSION: Our findings and the reviewed literature suggest that this complication is rare. Nevertheless, neurosurgeons should be aware of the potential risk and, if necessary, should be able to modify the technical procedure and the adjuvant treatment.

Biopsy, Needle↗
PubMed1987

Technique of stereotactic biopsy of two cranial target employing spherical coordinates to define a single trajectory.

A 'spherical coordinate system' has been developed to allow either stereotactic biopsy of two intracranial lesions using a single predetermined trajectory or biopsy of a single lesion through an existing burr hole. By means of the Gildenberg technique, the CT coordinates of the targets (or target and burr hole) are obtained. These are employed in three simple trigonometric equations to give three coordinates-two angles for the probe carrier (theta and alpha) and the radius (T) of a sphere, defined by one target as the center and the other target on the surface. These can be utilized in the Todd-Wells stereotactic frame. This system was evaluated using hollow skulls and crossed 30-gauge wire for phantom targets. The system was tried on ten different target combinations, and eight successful trajectories were obtained to within 3 mm. Two target combinations were inaccessible because of technical limitations of the Todd-Wells frame. This 'spherical coordinate system' can decrease the time to localize multiple targets as well as minimize the number of passes.

Biopsy↗
PubMed1978

[Chronic intracerebral electric stimulation for analgesia in man].

This report concerns the current status of the results of intraencephalic implantations carried out up to the present time in man with the aim of relieving certain forms of chronic pain. It places little emphasis upon the neuro-physiological basis of these implantations, which have been studied at length during previous reports. After presenting the overall results of operations carried out in the world up until September 1967, a critical study is undertaken: 1--In relation to the targets (Postero-Lateral Ventral Nucleus, posterior arm of the internal capsule, para-ventricular thalamic grey matter). 2--In relation to etiologies, both analytically (syndrome) by syndrome as well as in terms of synthesis (excess of pain perception-deafferentation). 3--In terms of various factors, such as: --technical requirements; --side ffects; --duration of "post effect" (residual analgesia after stimulation); --parallel action of drugs. Conclusions are drawn concerning future perspectives of this technique.

Brain↗
PubMed1999

CT-guided stereotactic biopsy of brain. Three years of experience.

In our center from 1995 up to now (08.06.99) we have performed 78 CT-guided stereotactic biopsies (SB) of brain. In all cases the stereotactic biopsy was performed as the first surgical, diagnostic procedure. Indications for SB were as follows (in brackets, the number of SBs): diffuse, inoperable tumor (43), tumor of central region of brain (19), multiple tumors (7), a change of the obscure nature in CT/NMR scan (15), stereotactic assistance of the "classic: craniotomy and surgery of tumor (4). Among 78 SBs in 49 cases the primary and in 13 cases--secondary (metastatic) brain tumors were diagnosed. In the remaining 16 cases nonspecific changes like gliosis or necrosis were found. Of 49 primary tumors 40 were gliomas. Different pathomorphological methods, including especially immunohistochemistry with GFAP, vimentin, p53, Ki-67, and topoisomerase II alpha if applied together, may at least partially help to overcome the problems of the differentiation of reactive and neoplastic gliosis. We found a grading system of gliomas according to Daumas-Duport very useful in interpretation of SB material. Our preliminary observations suggest that immunolabelling of the biopsy material by means of topoisomerase II alpha antibody may be very useful in SB since it gives technically very good results on smears and because on the grounds of what is known on this enzyme it is the "target" of many antineoplastic drugs and hence may indicate the potential sensitivity to drugs.

Biopsy↗
PubMed2004

A computer-generated stereotactic "Virtual Subdural Grid" to guide resective epilepsy surgery.

BACKGROUND AND PURPOSE: In selected patients undergoing epilepsy surgery, subdural electrode grids play an important role in localizing the epileptogenic zone and identifying eloquent cortex. Determining the relationship of the electrodes to underlying brain architecture traditionally has been difficult. This report describes and validates the use of an original computer-aided method that displays a representation of the electrode positions, based on postimplantation CT or MR findings, coregistered with a 3D-rendered image of the brain, on an image-guided surgery system. METHODS: Seventeen patients underwent the procedure with visual verification of the actual and virtual grids undertaken during the second (postimplantation) surgery. The accuracy of the Virtual Grid electrode positions was further studied in a subgroup of five patients during surgery by plotting the distance from the actual electrode positions by using an infrared stereotactic probe. RESULTS: The accuracy of the Virtual Grid electrode positions by visual inspection was satisfactory in all 17 cases. In the five cases in which quantitative measurements were performed, the mean error for the CT derived electrode positions was 3.4 mm (range 0.5-5.4) compared with the mean error for the MR-derived electrode positions of 2.5 mm (range 0.5-5.2). CONCLUSION: The Virtual Grid electrode positions were highly accurate in localizing the actual position of the subdural electrodes with both CT- and MR-derived images. The MR-derived electrodes demonstrated a trend toward better accuracy, but the CT images were quicker and easier to process. This technology has the potential to minimize both human and technical errors, allowing for a more precise tailoring of the cortical resection in epilepsy surgery.

Brain Mapping↗
PubMed1997

The Cyberknife: a frameless robotic system for radiosurgery.

The Cyberknife is a unique instrument for performing frameless stereotactic radiosurgery. Rather than using rigid immobilization, the Cyberknife relies on an image-to-image correlation algorithm for target localization. Furthermore, the system utilizes a novel, light-weight, high-energy radiation source. The authors describe the technical specifications of the Cyberknife and summarize the initial clinical experience.

Algorithms↗
PubMed1991

A probe for simultaneous sampling in stereotactic brain biopsy. Technical note.

A probe for stereotactic brain biopsy which allows to obtain two different samples along a single trajectory tract is presented. It consists of a cylindrical stainless steel probe which has two separate grooves. The pieces of tissue are shredded from the lesion by sliding a polyethylene cannula that fits around the probe.

Biopsy↗
PubMed2000

Role of fine-needle aspiration cytology in nonpalpable mammary lesions: a comparative cytohistologic study based on 308 cases.

We retrospectively evaluated the accuracy of fine-needle aspiration cytology (FNAC) in nonpalpable breast lesions detected by imaging techniques between 1995-1997. A total number of 308 lesions was investigated: 273 had been studied by means of either FNAC obtained under ultrasound (175 cases) or stereotactic guidance (98 cases). The overall sensitivity rate was 87.8%; specificity was 95.3%; the positive predictive value was 76.6%; the negative predictive value was 97.8%. Our results confirm that FNAC is quite effective in the approach to patients with nonpalpable breast lesions. It is particularly accurate in diagnosing malignancy, although a lower yield may be encountered in tumor types producing a desmoplastic stroma (tubular carcinoma, infiltrating lobular carcinoma) or in noncomedonic in situ ductal carcinoma. Discrepancy between a suspicious cytology and a negative histology is more frequent with benign lesions usually because of sampling mistake or technically inadequate smears. In particular, when smears are adequate, FNAC safely assists in ruling out the malignant lesions.

Adenocarcinoma↗
PubMed1978

Stereotactic radiofrequency hypophysectomy.

Clinical indications and technical details of RF hypophysectomy were reviewed. Evaluation of serveral hundred procedures toward pathologic and symptomatic amelioration ofmetastatic breast cancer and diabetic retinopathy, and also a few cases of intrasellar tumor, indicated sufficient benefit for endorsement in selected patients.

Breast Neoplasms↗
PubMed2001

Vacuum-assisted breast biopsy on digital stereotaxic table of nonpalpable lesions non-recognisable by ultrasonography.

The aim of this study was to evaluate accuracy of 11 G vacuum-assisted percutaneous biopsy (VAPB) carried out on digital stereotaxic table, on breast non-palpable lesions (NPLs), non-visible by US. Prospective study on 132 consecutive NPLs (126 patients) not reliably found by US; 82% showed microcalcifications. Surgical confirmation was obtained in all malignant cases and when VAPB reported atypical lesion (ductal or lobular), radial scar or atypical papillary lesion. All patients with benign results were included in a mammographic follow-up programme. Two cases could not be dealt with due to technical difficulties. One to 26 cylinders were obtained from the remaining 130 NPLs. Sixty-four lesions were surgically confirmed. Forty-six of the 47 malignancies were correctly diagnosed. In one case of a malignant tumour, an atypical lesion was classified with VAPB. All cases of histologically verified lobular carcinoma in situ, atypical ductal or lobular hyperplasia, radial scar or atypical papillary lesion were correctly diagnosed preoperatively. The remaining lesions were benign in VAPB, and after 1 year of follow-up, no false negative has been found. Based on this short-term follow-up, absolute sensitivity was 97.9%, absolute specificity 84.3% and accuracy was 99.2%. For predicting invasion, accuracy was 89.1%. Vacuum-assisted percutaneous biopsy is a very accurate technique for NPLs which are not detectable by US. It can replace approximately 90% of DSB with no important complications, avoiding scars and providing a higher level of comfort.

Adult↗
PubMed1987

New diagnostic and therapeutic tools in stereotaxy.

A definitive pathoanatomic diagnosis was achieved in 14 biopsies of deep cerebral tumors in which the Laitinen CT adapter was utilized. In 5 patients, a third-ventricular colloid cyst was aspirated or resected by stereotactic endoscopy, with excellent results after a mean follow-up time of 2.5 years. Several instruments, including a diagnostic ultrasound probe, an ultrasonic aspirator, a combination laser and an endoscope can be used stereotactically when mounted on a special instrument carrier. Integration of the Laitinen stereotactic device and the CT adapter was developed to allow noninvasive stereotactic radiotherapy in a conventional fractionation schedule by a standard linear accelerator. Technical experiences using this radiosurgical system in over 30 sessions for treating inoperable cerebral arteriovenous malformations are promising, but the follow-up time is too short for evaluating the clinical effect.

Adult↗
PubMed2001

Refractory idiopathic intracranial hypertension treated with stereotactically planned ventriculoperitoneal shunt placement.

OBJECT: Ventriculoperitoneal (VP) shunts have not been widely used for idiopathic intracranial hypertension (IIH) because of the difficulty of placing a shunt into normal or small-sized ventricles. The authors report their experience with stereotactic placement of VP shunts for IIH. METHODS: The authors reviewed the clinical records of all patients in whom stereotaxis was used to guide the placement of a VP shunt for IIH at their institution. All shunts were placed using stereotactic guidance to target the frontal horn of the lateral ventricle. Patients were contacted at a mean postoperative interval of 15.1 months. No patients were lost to follow up. The authors identified 13 patients who underwent placement of a stereotactically guided VP shunt for IIH over a 6-year period. A trial of either acetazolamide or steroid therapy had failed in all patients. Prior surgical treatments included optic nerve sheath fenestrations in seven patients and cerebrospinal fluid diversionary procedures, other than stereotactic VP shunt procedures, in nine patients. Twelve patients reported excellent or good durable symptomatic relief at the time of follow up. No patient suffered progression of visual deficits. Four patients experienced persistent headaches following the procedure. Three patients required a revision of the VP shunt for technical failure. CONCLUSIONS: Stereotactically guided VP shunt placement is an effective and durable treatment option in many cases of IIH that are refractory to more traditional medical and surgical approaches.

Adolescent↗