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PubMed1998

[Interventional methods in breast diagnosis. Histological vs. cytological evaluation of core cut biopsies of the breast].

High speed core cut biopsies of breast tumors, sonographically or stereotactically guided, allow an histological examination of the tumor without surgery. It can be used prior to operation for the confirmation of a breast cancer and it can avoid unnecessary breast surgery in benign tumors. Unfortunately, only some centers are equipped with a pathology unit that allows an immediate histological examination. But often these institutes are provided with an experienced cystologist. Thus, the question arises if a cytology taken from the core cut biopsy is as reliable as an histological examination. In a prospective study we performed unroll-cytologies in core cut biopsies of 173 breast tumors in 169 patients consisting of 122 malignant and 51 benign tumors. Histology of core cut biopsies was proven by operational histology in all malignant and in 5 benign tumors. Histology of core cut biopsies could not be judged in 2 cases (lymphoma, gallert carcinoma). Cytological slide preparations were technically inadequate in 4 cases. The false negative rate of histology was 1/120 and 27/120 in cytology. Histology compared with cytology showed the following results: sensitivity 99.2% versus 77.5%, specificity 100% versus 95.9%, positive predictive value: 100% vs. 97.8%, negative predictive value: 98.1% vs. 63.5%, and accuracy: 99.4% vs. 82.8%. The sensitivity of cytology was much worse than that of histology of core cut biopsies. Thus, in our opinion cytology can provide a quick diagnostic orientation, but it cannot replace the more reliable histological examination. Diagnostic or therapeutic decisions should be based upon the more reliable histological results.

Biopsy↗

PubMed1998

Linac radiosurgery at the Joint Center for Radiation Therapy.

The Joint Center for Radiation Therapy (JCRT) has treated intra-cranial lesions with high-dose single fraction stereotactic radiosurgery (SRS) since 1986 and with multi-fraction stereotactic radiotherapy (SRT) since 1992. This paper describes the JCRT techniques for treatment planning and delivery for SRS, and to a limited extent for SRT. LINAC quality assurance, treatment delivery, and patient management for stereotactic radiosurgery and stereotactic radiotherapy technique are closely related at the JCRT, although differences exist. An historical retrospective of our experience with stereotactic techniques including imaging modalities, treatment planning techniques, optimization methods, and treatment delivery is presented. Three treatment planning approaches, single isocenter, multiple isocenter, and micro-jaw field shaping are used to demonstrate the capabilities and technical dosimetric features of each approach. The major planning differences and clinical of each technique are described. From our experience, lesions less than 3.0 cm in maximum extent are well treated with circular fields using either a single or multiple isocenter configuration. Lesions greater than 3.0 cm in maximum extent usually benefit from field shaping using the micro-jaws. For these large lesions, the shaped field approach typically improves the dose homogeneity as well as reduces the amount of healthy brain irradiated. Our physicians choose between the three techniques to meet the desired clinical outcome the patient's situation requires.

Boston↗

PubMed1998

Sequential outer table craniotomy a in hyperossified meningioma. Technical note.

A hyperossified meningioma with significant calvarial thickening is fairly common. Craniectomy of the involved region followed by cranioplasty is usually required to resect the bone overgrowth. However, in some cases, the hyperossified calvaria is too thick to allow safe penetration with a craniotome or trephine. In this report, the authors present a technique for preserving the outer calvaria while still resecting the majority of the underlying tumor mass. The key is to perform a craniotomy in a region adjacent to the hyperossified bone and to remove the tumorous, ossified inner table through this "window" by means of a high-speed drill. A second craniotomy can then be performed over the undermined area; this maneuver can be advanced and repeated until the tumor is resected. Frameless stereotactic guidance and microplates are useful in performing this procedure.

Craniotomy↗

PubMed2000

Localization of breast lesions shown only on MRI--a review for the UK Study of MRI Screening for Breast Cancer. Advisory Group of MARIBS.

The UK study of screening for breast cancer compares mammography and dynamic contrast enhanced MRI of the breast in women at high genetic risk of developing cancer. Owing to the high sensitivity of MR in the breast, it is anticipated that some lesions will be visible only on MR. A key issue for the study is how to localize these lesions for histological verification and removal. This article reviews available methods and describes the current UK expertise and recent European developments. The use of MR compatible wires and markers has been explored in a phantom. The use of these markers in vivo is demonstrated in a case imaged by MR and mammography and further discussed. The susceptibility artefacts produced on MRI, and technical properties associated with these needles, wires and markers are discussed. The clinical pathway by which these lesions will be worked up for the study, and the quality control procedures for keeping the number of such biopsies to a minimum, are described. There is an urgent need for further centres in the UK to become proficient at removing lesions found only on MRI in support of this study and other breast MRI applications. The management of these lesions must be resolved in order to realize the full potential of MRI for screening for breast cancer in women at genetic risk, and for other diagnostic applications.

Algorithms↗

PubMed2001

Microsurgical removal of a petrous apex meningioma after stereotactic radiation: technical case report.

OBJECTIVE AND IMPORTANCE: Stereotactic radiation is increasingly advocated as a primary treatment option for benign cranial base lesions. The clinical course of the patient reported herein raises questions regarding the rationale for initiation of radiotherapy to a petrous apex meningioma before microsurgery. CLINICAL PRESENTATION: We report a 50-year-old woman who experienced medically refractory trigeminal pain. She was diagnosed with a meningioma around the petrous apex and treated by fractionated stereotactic radiation. After a short period of alleviation accompanied by hypesthesia, the pain returned in a previously unknown and violent fashion. INTERVENTION: Complete tumor removal through a retrosigmoid intradural suprameatal approach resulted in immediate and permanent pain cessation. CONCLUSION: Radiotherapy should be withheld for benign and accessible tumors of the cranial base until the option of radical microsurgical treatment has been explored.

Combined Modality Therapy↗

PubMed1990

Multiloci stereotactic transplantation of autologous adrenal medullary tissue to the putamen and caudatum in Parkinson's disease. Technical note.

Adrenal to striatum transplants may be effective, but many technical issues are still debated. A procedure whereby a number of grafts were stereotactically placed at the putamen and caudatum is reported. It enables grafting deep nuclei, such as the putamen, the most denervated structure in Parkinson's disease, and allows a widespread spatial distribution of multiple grafts within these huge targets, conceivably enhancing the local release of neurotransmitters at the site or in the vicinity of the denervated receptors. It also enables the use of a sizeable volume of tissue, presumably a crucial but as yet unknown factor. Although preliminary, the present data seem to warrant further clinical trials.

Adrenal Medulla↗

PubMed1998

Stereotactic ventriculoperitoneal shunt for idiopathic intracranial hypertension: technical note.

OBJECTIVE: Lumboperitoneal shunting is the bastion of neurosurgical management for idiopathic intracranial hypertension (IIH). However, recent studies document a high failure rate for this procedure. The present study was designed to explore the feasibility of placing ventriculoperitoneal shunts under stereotactic control into patients with IIH as an alternative to lumboperitoneal shunting. METHODS: Seven patients with IIH for whom medical management had failed underwent stereotactic implantation of ventriculoperitoneal shunts. RESULTS: Shunt placement was successful and uncomplicated in each case. Five of seven patients experienced complete resolution of papilledema. The remaining two patients showed resolving papilledema. Six of seven patients experienced resolution of headache. The remaining patient continued to have headaches despite a radionuclide study demonstrating normal shunt function. CONCLUSION: Our results suggest that stereotactic ventriculoperitoneal shunting may be a reasonable alternative to lumboperitoneal shunting in those patients with IIH who require surgical intervention.

Adult↗

PubMed1995

Implantation of fetal tissue for the management of Parkinson's disease: a technical note.

A relatively simple method for implanting fetal tissue within the human basal ganglia is described. Stereotactic techniques are used to deposit 14 to 16 strands of fetal mesencephalic tissue in a linear array within the putamen bilaterally. To eliminate the need for targeting each needle pass independently, we have devised a novel rotating template/micromanipulator apparatus that can be mounted on a Cosman-Roberts-Wells stereotactic frame. The template contains two parallel columns of nine holes, all spaced at 4-mm intervals. It can be aligned to the longitudinal axis of the putamen and targeted with coordinates for the center point of the putamen. Surgery is performed on an awake patient. Short-term morbidity (4-6 wk) in the form of variability of Parkinsonian signs, particularly "off" symptoms and mild confusion, appears to be the rule with simultaneous bilateral implants.

Equipment Design↗

PubMed1997

Split cannula method for accurate placement of an electrode for deep brain stimulation: technical note.

OBJECTIVE: We describe a "split cannula method" for accurate placement of a deep brain stimulation electrode. This method eliminates the risk of displacement of the electrode when withdrawing the outer guide cannula. METHOD: A separate short guide cannula is covered over the distal part of a long cannula for microrecording or macrostimulation. After confirmation of the stimulation point, the short cannula is fixed with an accessory-holding device and the long cannula is pulled out. The electrode for deep brain stimulation is inserted through the short cannula. Because this cannula is much shorter than the electrode, securing the stimulation electrode at any withdrawal stage of the outer guide cannula is always possible. RESULTS AND CONCLUSION: With this simple method, we experienced no displacement of the stimulation point during stereotactic insertion of a deep brain stimulation electrode. This method can be easily adapted to any stereotactic frame.

Brain↗

PubMed1991

Intraoperative calibration of the Patil stereotactic system during computed tomography (CT) guided stereotactic procedures--a technical note.

A method for intraoperative calibration of the Patil stereotactic system is described. After adjusting the z and y coordinates, a marker is placed in the pivot block and a CT scan is obtained. The presence of the marker in the indicator block on the same horizontal line as the target, on the image of the target, would indicate that the y and z coordinates adjustments are accurate. After the arc is attached with the x coordinate adjusted, a CT scan is obtained with the arc vertical and the probe holder at zero angle (from the vertical) position. The presence of the middle of the probe holder in the same vertical line as the target would indicate accurate x coordinate adjustment. This technique, which can be applied also to other stereotactic systems, allows the surgeon to check not only the accuracy of the system but also the accuracy of the procedure prior to inserting the probe into the brain.

Brain↗

PubMed1989

Non-Hodgkin's lymphoma involving the brain. Diagnostic usefulness of stereotactic needle biopsy in combination with paraffin-section immunohistochemistry.

A stereotactic needle biopsy was examined for applicability in diagnosing brain non-Hodgkin's lymphoma (NHL), because the procedure is far less aggressive than biopsy by open surgery. Formalin-fixed materials including four stereotactic specimens were available from nine patients with brain NHL. In addition to routine histopathology and histochemistry, paraffin-section immunohistochemistry was performed using a panel of monoclonal antibodies suited to such sections. Although several histopathological features characteristic of brain NHL could not be evaluated in three of the four stereotactic specimens owing to the small size of the specimens and partial invasion by lymphoma cells, the lesions in all cases could be characterised by immunohistochemistry. Examination for cytoplasmic immunoglobulin (cIg) was also performed, but specific identification of cIg was difficult in five cases because of diffuse background staining and passive diffusion of plasma protein into the cells during tissue processing. A review of the literature indicates the technical difficulty in cIg staining, since the incidence of cIg-positive cases in an individual study varied considerably, and lymphoma cells in 15 of 128 cIg-positive brain NHL cases have been reported to possess both light chains. From these findings, together with the relative difficulty in obtaining fresh tissues for study, it is concluded that, when the specimens are to be examined by paraffin-section immunohistochemistry using the above monoclonal antibodies, stereotactic needle biopsy is a useful, less aggressive method for diagnosing brain NHL.

Adult↗

PubMed1991

Technical and therapeutic aspects of dynamic stereotactic radiosurgery.

A treatment procedure that results in a uniform dose in a single fraction over the entire treatment volume while minimizing the dose to other tissues has been developed to treat intracranial lesions such as arteriovenous malformations (AVMs). This technique is called dynamic stereotactic radiosurgery. Its main characteristic is simultaneous and continuous gantry and couch motion during the treatment procedure. It employs an isocentrically mounted linear accelerator as the source of radiation. Target localization is determined by digital subtraction angiography and CT. From results obtained in other centres, this technique has shown that an AVM less than 2.5 cm in diameter has an 85% chance of being completely obliterated within two years after a single treatment of stereotactic radiosurgery. This technique is suitable for those patients with inoperable, surgically inaccessible lesions, or whose current medical profile shows them to be high-risk candidates for surgical intervention.

Angiography, Digital Subtraction↗

PubMed2003

Endoscopic removal of thalamic hematoma: a technical note.

OBJECT: To minimize invasiveness, an endoscopic surgical technique under stereotactic guidance is described for removal of thalamic hematoma. SURGICAL TECHNIQUE: A burr hole is placed at a point 3 cm above the glabella and 3 cm lateral from the midline. A transcortical transventricular puncture is performed with a stainless steel tube under stereotactic guidance. The tube is mounted to a metal holder. Through this tube, a rod-lens working channel endoscope and surgical instruments are inserted for visualization of the thalamus and evacuation of the hematoma. Compared with the endoscopic approach through the shortest distance of viable brain tissue, this technique allows removal of the hematoma in the ventricular space and thalamus simultaneously. The case of one patient with thalamic hemorrhage and obstructive hydrocephalus, caused by an intraventricular blood clot, is reported for surgical demonstration. CONCLUSION: An endoscopic technique for removal of thalamic hematoma with the aid of stereotactic guidance, which allows precise targeting of the lesion, is reported.

Aged↗

PubMed2000

The "optimal" burr hole position for endoscopic third ventriculostomy: results from 31 stereotactically guided procedures.

ETV is a well established and successful method in contemporary neurosurgery. With growing experience there is a more efficient patient selection and further advances in technical know how. We evaluated retrospectively a consecutive group of 27 patients who were treated in our institution by stereotactic guided ETV between 1992 and 1996. When reviewing their postoperative imaging studies (MRI/CT) we could measure the position of the burr hole as port of entry for the rigid endoscope in 17 out of 23 finally selected patients. The median lateral position was 28 mm (mean 26.5 mm) from the midline and 8 mm (mean 6.5 mm) anterior of the coronal suture. We conclude that the optimal burr hole position should be 3 cm lateral to the midline and 1 cm anterior of the coronal suture, in the patients with normal anatomical findings.

Adolescent↗

PubMed1956

Focal destruction of nervous tissue by focused ultrasound: biophysical factors influencing its application.

Ultrasound at frequencies of 1.0 mcps and 2.5 mcps can be focused by a suitable lens system to produce a small region of high vibrational intensity. The concentrated energy within and around the focal region can be used to destroy structures of the central nervous system. The extent of destruction depends upon: (a) the size of the focal region, which varies inversely with the frequency, (b) the ultrasonic intensity, (c) the duration of exposure, and (d) the physical and physiologic characteristics of the tissue under irradiation. With proper choice of ultrasonic dosage, mice were rendered monoplegic by destruction of one-half of the spinal cord without demonstrable injury to the skin or subcutaneous tissues through which the converging ultrasonic beam had been transmitted. In similar fashion, focal lesions were produced in the basal ganglia of living cats by stereotaxic transdural application of a focused ultrasonic beam delivered through the superior aspect of the cerebral hemispheres. Histologic studies of mouse spinal cords and cat brains offered evidence that the fiber tracts of the central nervous system are more vulnerable to ultrasonic irradiation than aggregates of cell nuclei or vascular structures. The destructive action of the ultrasound is apparently a result of mechanical strain combined with a rise in temperature at the focus of the beam. The heating factor was found to assume greater importance under conditions of high intensity and continuous (rather than pulsed) irradiation. Trypan blue staining and radioautography using P(32) have been employed to identify the lesions 1 hour after irradiation. This has been a valuable adjunct in our attempts to determine the accuracy of placement of the lesions and their size. Perhaps more important, however, is the indication from these studies that ultrasonically produced lesions may offer a useful method for investigation of the nature of the blood-brain barrier. "Target studies" were undertaken to determine the precision with which lesions of predetermined size could be placed at predetermined sites in the basal ganglia of the cat. Results to date have been promising, but it is our opinion that further technical improvement will be necessary before ultrasound can be used as an accurate method for placing discrete lesions within the human brain.

Animals↗

PubMed1991

A frameless, armless navigational system for computer-assisted neurosurgery. Technical note.

A computer-assisted neurosurgical navigational system has been developed which displays intraoperative manipulation on the preoperative computerized tomography (CT) scans or magnetic resonance (MR) images. The system consists of a three-dimensional digitizer, a personal computer, and an image-processing unit. Utilizing recently developed magnetic field modulation technology, the three-dimensional digitizer determines the spatial position and orientation angles of the resin probe, triangle-shaped pointer, or suction tube with a small attached magnetic field sensor. Four fiducial markers on the scalp were used to translate the spatial data of the probe onto the preoperative CT scans or MR images of the patient. With this frameless, armless navigational system, CT or MR-imaging stereotaxy can be applied to conventional open neurosurgery without limiting the operative field or interfering with the surgical procedures.

Adult↗

PubMed2005

A contralateral, transfrontal, extraventricular approach to stereotactic brainstem biopsy procedures. Technical note.

The authors report on the technique and results of stereotactic biopsy for intrinsic lateral pontine and medial cerebellar lesions via a contralateral, transfrontal, extraventricular approach. Multiplanar stereotactic magnetic resonance imaging was used to plan an intraparenchymal approach, thus limiting the number of crossed pial surfaces to one and eliminating the need to cross ependymal surfaces. After the administration of a local anesthetic agent with light intravenous sedation, six patients harboring intrinsic lateral pontine lesions underwent biopsies via this intraparenchymal approach with 100% diagnostic yield and no operative morbidity. In comparison to the ipsilateral transfrontal approach, the contralateral approach laterally expands the infratentorial area accessible during biopsy to include the lateral pons and middle cerebellar peduncle. The contralateral, transfrontal, extraventricular approach is a useful, straightforward and safe alternative to the suboccipital transcerebellar and ipsilateral, transfrontal, transtentorial routes for reaching lesions of the lateral pons and middle cerebellar peduncle.

Adenocarcinoma↗

PubMed1997

Identification and localization of intracerebral vessels by microvascular doppler in stereotactic pallidotomy and thalamotomy: technical note.

OBJECTIVE: To identify intracerebral vessels in proximity to the target for thermocoagulation in functional neurosurgery, we use a microvascular doppler sensor held in a special supporting needle that fits in the straightening cannula for the thermocoagulation needle. TECHNIQUE: After insertion of the straightening cannula aimed at the stereotactic target, the microvascular doppler probe positioned at the tip of a supporting hollow needle is advanced through the cannula. The proximal micrometer gauge indicates the depth of the tip of the doppler probe. By setting the doppler device to the shortest focusing depth (0.1 mm), the maximum pulsatile vascular sound indicates the depth of the vessel. RESULTS AND CONCLUSION: A prominent vascular sound was identified in 3 of 13 cases. By adjusting the depth of the target, no major bleeding was experienced after thermocoagulation lesions were made. This technique secures and protects the fragile microvascular doppler and identifies any significant arterial vessels at the stereotactic target, thus avoiding vascular injury.

Cerebral Arteries↗