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R Spiegelmann

Publications and source records attributed to R Spiegelmann.

At least 19 recordsLinked to original sources
PubMed2001

Linear accelerator radiosurgery for vestibular schwannoma.

OBJECT: The use of radiosurgery in the treatment of acoustic neuromas has increased substantially during the last decade. Most published experience relates to the use of the gamma knife. In this report, the authors review the methods and results of linear accelerator (LINAC) radiosurgery in 44 patients with acoustic neuromas who were treated between 1993 and 1997. METHODS: Computerized tomography scanning was selected as the stereotactic imaging modality for target definition. A single, conformally shaped isocenter was used in the treatment of 40 patients; two or three isocenters were used in four patients who harbored very irregular tumors. The radiation dose directed to the tumor border was the only parameter that changed during the study period: in the first 24 patients who were treated the dose was 15 to 20 Gy, whereas in the last 20 patients the dose was reduced to 11 to 14 Gy. After a mean follow-up period of 32 months (range 12-60 months), 98% of the tumors were controlled. The actuarial hearing preservation rate was 71%. New transient facial neuropathy developed in 24% of the patients and persisted to a mild degree in 8%. Radiation dose correlated significantly with the incidence of cranial neuropathy, particularly in large tumors (> or = 4 cm3). CONCLUSIONS: Single-isocenter LINAC radiosurgery proved to be an effective treatment for acoustic neuromas in this series, with results that were comparable with those reported for gamma knife radiosurgery and multiple isocenters.

Adult↗
PubMed1999

Application of transcranial doppler ultrasonography for the diagnosis of brain death.

OBJECTIVE: To determine the clinical validity of transcranial Doppler ultrasonographic (TCD) signs of total cerebral circulatory arrest for confirmation of brain death and to define the test protocol. DESIGN: Study of a diagnostic test. SETTING: General and neurosurgery intensive care units. PATIENTS: 137 patients in a coma (Glasgow Coma Score 3-5), caused by various pathological conditions, observed from January 1992 to July 1998. 84 patients met the clinical criteria of brain death; 43 patients out of 137 received sedative drug therapy and 31 of these developed brain death. RESULTS: Total cerebral circulatory arrest was demonstrated by TCD in 81 patients. All of them proved to be brain dead according to subsequent clinical examination In 29 of 31 patients who had received sedative drug therapy TCD examination showed total cerebral circulatory arrest 12-48 h before the formal confirmation of the diagnosis. In 1 out of 84 clinically brain dead patients a false negative result was obtained. In 2 of 84 cases, no clear signals from intracranial vessels were obtainable. Fifty-three patients who did not meet the clinical criteria for brain death showed no TCD signs of total cerebral circulatory arrest. The specificity of the TCD test for confirmation of brain death was 100 % and the sensitivity 96.5 %. CONCLUSIONS: In agreement with previously published data, we conclude that TCD ultrasonography is a highly specific and sensitive confirmatory test and should be included as an additional test in the protocol for the assessment of brain death.

Adolescent↗
PubMed1999

Radiosurgery for acoustic neurinomas (vestibular schwannomas).

BACKGROUND: Radiosurgery is a therapeutic technique characterized by the delivery of a single high dose of ionizing radiation from an external source to a precisely defined intracranial target. The application of radiosurgery to the treatment of acoustic neurinomas has increased substantially in the last decade. Most of the published experience pertains to the use of the gamma knife. OBJECTIVES: To report the experience at the first Israeli Linear Accelerator Radiosurgery Unit in the management of 44 patients with acoustic neurinomas. METHODS: We analyzed the clinical records and imaging studies of all patients undergoing radiosurgery for acoustic neurinomas between 1993 and 1997, and quantified the changes in tumor volume, hearing status, and facial and trigeminal nerve function. The contribution of radiation dose and original tumor volume upon those variables was also studied. RESULTS: At a mean follow-up of 32 months (range 12-60), 98% of the tumors were controlled (75% had shrunk; 23% had stable volume). The actuarial hearing preservation rate was 71%. New transient facial neuropathy developed in 24% of the patients, persisting in mild degrees in 8%. Neuropathy correlated primarily with tumor volume. Tumors with volumes > 4 ml were at high risk when marginal radiation doses were > 1,400 cGy. Dose reduction to a maximum of 1,400 cGy produced no neuropathies in the last 20 patients, still preserving tumor control rates. CONCLUSIONS: Radiosurgery is an effective and cost-efficient therapeutic modality for newly diagnosed acoustic neurinomas in the elderly or medically infirm population, and for all residual or recurrent tumors after conventional surgery.

Adult↗
PubMed1996

CT-target determination in postero-ventral pallidotomy: a universal method. Technical note.

Stereotactic targeting of the postero-ventral pallidum (PVP) presents special challenges to the surgeon 1) The target is in intimate relation to the optic tract and the internal capsule. 2) Proper angulation of the trajectory is crucial to achieve optimal effects given the long craniocaudal extension of the PVP. 3) The PVP is difficult to identify on computerized tomography (CT): the border between the internal capsule and the pallidum is usually not apparent. Potential sources of error in target determination include: - angulation of the scanning plane in relation to the intercommissural plane; - projection of the reference points (anterior commissure/posterior commissure [AC/PC]) results in the foreshortened intercommissural line, affecting the Y co-ordinate; - small tilts between the CT gantry and the stereotactic frame affect determination of the X and Z co-ordinates. Correction of these sources of error is done with basic trigonometric algorithms. The authors have developed a rapid method of stereotactic co-ordinate calculation which avoids the need to perform error-prone calculations under the pressure of operating room conditions. 1) The frame is applied with its basal plane corresponding roughly to the orbito-meatal line. 2) Thin CT slices (2 mm increments) are obtained through the area of interest and the slices are printed. 3) The major reference points (Foramen of Monro, AC, PC) are identified and marked. The PC point is projected onto the film containing AC (or viceversa if the PC slice is caudal to AC). 4) The intercommissural distance is measured, and the true length is obtained from a correction graph. The Y co-ordinate is then calculated as 1/2 ICL + 2 mm [towards AC]. 5) The slice corresponding to the target [Z co-ordinate] is obtained from a correction graph that takes into consideration the gap [number of slices] between AC and PC. 6) The X co-ordinate is placed 20 to 22 mm from midline. A graph that takes into consideration the coronal tilt of the stereotactic frame in relation to the CT gantry allows for final corrections of the X and Z co-ordinates. This step-by-step simple method of co-ordinate calculation can be used with any CT-compatible stereotactic frame.

Brain Mapping↗
PubMed1994

CT target selection in stereotactic anterior capsulotomy: anatomical considerations.

The first communications concerning stereotactic bilateral anterior capsulotomies were reported by Talairach and Leksell. This procedure has become established for the management of otherwise intractable anxiety neuroses and obsessive compulsive disorders, with a reported success rate of 70% in different series. It has been stressed that results are closely related to the extent of the lesion. The desirable lesion has a tubular shape with a length of 15-18 mm in the coronal axis. This shape is achieved by step withdrawal of a 4- to 5-mm electrode tip along a proper trajectory. A precise angulation of the trajectory is crucial to proceed without lesioning of the adjacent bordering caudate nucleus or putamen in the coronal plane. In the sagittal plane, it has to remain within the limits of the anterior capsula interna and avoid an excessive posteroanterior obliquity to ensure that the entry point through the cortex remains in the prefrontal noneloquent area. To achieve this trajectory, a target 5 mm posterior to the anterior border of the frontal horn, as seen on CT, at the level of the foramen of Monro has been suggested, along with a precoronal burr hole placed 20 degrees from the midline. Following these guidelines we have found the resulting lesions to be excessively anterior, with exclusion of their first 4- to 5-mm deep component. If the same target point is selected at two different axial levels to fix a trajectory, it usually results in an anteriorward trajectory that might require an entry point too close to the motor cortex, because the anterior horn reaches more rostrally as it deepens.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Mapping↗
PubMed1993

Continuous irrigation-drainage of the subdural space for the treatment of chronic subdural haematoma. A prospective clinical trial.

Thirty seven adult patients which chronic subdural haematoma were randomized into two groups. Eighteen patients served as controls and underwent evacuation of the haematoma via burr holes and a gravity dependent closed-system drainage. Nineteen patients comprised the study group. These patients had a continuous irrigation-drainage system installed in an attempt to facilitate the removal of fibrinolytic substances present in the haematoma fluid and to try to reduce the rate of rebleeding from the haematoma membranes. No differences were found between the pre- and post-operative clinical status, haematoma volumes and the degree of CT changes between the two groups. The complication rate was similar in the two groups. One patient in the study group and three patients in the control group required an extended period of drainage (24-48 hours) prior to the removal of the drains. All patients improved following the procedures. Within 30 days post the initial evacuation of the chronic subdural haematoma, re-operation was required in only one patient in the study group as opposed to four of the controls. This difference was not however statistically significant. When the need for re-operation was combined with the need for extended drainage period, a significant difference was shown in favour of the study group. These results indicate that drainage combined with continuous irrigation of the subdural space does not affect the clinical outcome of the patients, but significantly reduces the frequency of inadequate drainage of the haematoma and prevents longer drainage periods and repeated operations.

Aged↗
PubMed1993

LINAC radiosurgery: an animal model.

Fifteen cats were irradiated with an animal LINAC (linear accelerator) radiosurgery device. After 6 months, they were studied with gadolinium-enhanced magnetic resonance (MR) imaging, gross pathology after Evans blue perfusion, and histopathology. The lesion size was relatively constant in the cats receiving a dose of 7500, 10,000, 12,500, or 15,000 cGy to the 84% isodose line of a 1-cm collimator. The composition of the lesion correlated with dose: the lower-dose lesions were found histologically to contain areas of edema, demyelination, reactive gliosis, and vascular proliferation; the higher-dose lesions contained increasing amounts of hemorrhage and coagulative necrosis. The borders of the lesions were sharply demarcated from surrounding normal brain. Gadolinium-enhanced MR studies correlated well with areas of blood-brain barrier breakdown, as confirmed by areas of Evans blue staining. This model could serve as the basis for further studies of the biological effects of LINAC radiosurgery.

Animals↗
PubMed1992

Limitations of angiographic target localization in planning radiosurgical treatment.

Planning radiosurgical treatment for cerebral arteriovenous malformations requires accurate definition of the true tridimensional size and shape of the nidus. Over- or underestimation of these parameters may result in undue irradiation of normal brain tissue or suboptimal irradiation coverage of the malformation leading to treatment failure. Angiography is not an ideal database for radiosurgery of arteriovenous malformations. Its shortcomings include planar representation of a tridimensional volume and simultaneous visualization of feeding arteries and draining veins overlapping with the nidus and obscuring its outline. Two illustrative clinical cases of these angiographic inadequacies are presented. Stereotactic, contrast-enhanced computed tomography may provide, in selected cases, better spatial definition of the nidus and superior anatomic detail for the final design of the radiosurgical isodose distribution.

Adult↗
PubMed1992

Linear accelerator radiosurgery at the University of Florida.

The University of Florida radiosurgical project began in 1986 with the following design criteria: the most accurate radiosurgical device possible, state-of-the-art computer hardware and software for dose planning, and a number of collimators sufficient to treat any lesion homogeneously. In this article we have reviewed how these goals have been met. Physical aspects of this device (accuracy, dose gradient, and dose-planning speed) as well as clinical results compare favorably with any other radiosurgical experience. We believe that LINAC radiosurgical systems are advantageous in terms of cost, variety of collimator sizes available, and currently available sophistication of computerized dose planning. In the near future, the development of conformal treatment may significantly change the entire field of radiosurgery by offering heretofore unobtainable dose plans for irregularly shaped lesions. In addition, LINAC systems may be adapted for stereotactically focused fractionated radiation therapy and for radiosurgical treatment of lesions elsewhere in the body. Accuracy and computer sophistication notwithstanding, we cannot emphasize strongly enough our belief that the least important determinant of radiosurgical results is the machine used to deliver the radiation. It is absolutely vital that all groups undertaking radiosurgery include neurosurgeons, radiation physicists, and radiation therapists who have spent considerable time studying and learning the myriad details necessary to produce consistently good results. All radiosurgical patients must be followed up carefully and studied so that we can learn how to better apply this technique. Only patients who are not candidates for conventional surgery should be treated radiosurgically, at least until much more is known about long-term success and complication rates. A patient never should be treated radiosurgically simply because the referring or treating neurosurgeon is uncomfortable with proven conventional procedures. All groups performing radiosurgery should strive to adhere to the highest possible standards. We are all responsible for verifying the adequacy of our radiosurgical systems. We are all responsible for selecting our patients well, treating them with a team approach that applies the latest available knowledge of our field, following up closely, and reporting our results honestly and thoroughly so that all can benefit. We owe this, at least, to our patients and to neurosurgery.

Adult↗
PubMed1991

Rapid determination of thalamic CT-stereotactic coordinates: a method.

The anterior and posterior commissures (AC; PC) are the most frequently used reference points for target determination in functional stereotactic surgery. Computerized tomography (CT) has been slow in replacing ventriculography for identification of these points, primarily because in most methods described to date, the AC/PC plane had to be identified by reformatted CT images or cumbersome mapping procedures. The authors describe their methodology for determination of functional CT-stereotactic coordinates using the Brown-Robert-Wells (BRW) stereotactic system, axial CT imaging, and a proportional method to rapidly scale standard stereotactic map coordinates to the diencephalic size of any individual patient. 1. CT gantry angulation coinciding with Twining's line allows rapid identification of the AC/PC plane on axial CT. 2. Determination of the AC/PC distance with the "measure distance" function of the scanner enables the surgeon to rapidly find the proportional coordinates for either V.O.P., V.im., or V.C. 3. This localization method takes little more time than a routine stereotactic biopsy. Its application is easy, demanding only a few minutes of CT-console time, employing the standard computer software available in every current CT scanner. The method was been successfully employed in 25 functional thalamic procedures.

Electric Stimulation↗
PubMed1991

Spinal intradural arachnoid cysts.

Three patients with indural spinal arachnoid cysts presented with back or neck pain of several months' duration. They gradually developed weakness and difficulty in walking followed by rapid deterioration with signs of spinal cord or nerve root compression. Radiological studies showed a posteriorly located mass in the cervical, dorsal and lumbar region; one cyst filled with contrast medium and the diagnosis of the others was made at operation. Surgery resulted in full recovery of two patients and partial recovery of the third.

Adolescent↗
PubMed1991

Postoperative spinal epidural empyema. Clinical and computed tomography features.

Epidural empyema is a rare complication of elective spinal surgery. Four such cases are described. The clinical features of this postoperative complication were surprisingly vague and misleading. Fever was uncommon. Local inflammatory signs or rapid neurologic deterioration were absent. Computerized tomography proved useful in diagnosis and follow-up. Unlike spontaneous spinal epidural abscess, postoperative spinal epidural empyema had a benign course. Causative bacteria were miscellaneous. Surgical evacuation of the purulent collection and appropriate antibiotic therapy resulted in cure in all cases.

Adult↗
PubMed1991

Anatomic examination of a case of open trigeminal nucleotomy (nucleus caudalis dorsal root entry zone lesions) for facial pain.

Nucleus caudalis dorsal root entry zone lesions (open trigeminal nucleotomy) are a surgical procedure which can achieve pain control without major complications in the difficult clinical setting of deafferentation-type facial pain. Two patients are reported, who had relief of pain, but also experienced neurological complications. One patient succumbed to pulmonary complications, which provided the opportunity for anatomic analysis of the lesioned area, which is discussed in detail. Potential modifications of the surgical technique are suggested.

Afferent Pathways↗
PubMed1991

A device for experimental radiosurgery.

As radiosurgery evolves into a widely available treatment modality for a variety of intracranial lesions, the need for basic research concerning the radiobiology of high-dose single-fraction ionizing radiation becomes crucial. A device especially designed for experimental radiosurgery in the cat is described. It incorporates basic parts of the Kopf stereotactic frame for accurate target positioning. A motorized pendular movement of the machine is used to describe a radiation arc, while the radiation source (either a linear accelerator or a cobalt machine) remains stationary. The pathway of the different radiation arcs is modified by rotation of the animal platform around the machine isocenter. Mechanical accuracy tests have shown a maximal alignment error of 0.15 mm, comparing favorably with that reported for modern clinical radiosurgical systems.

Animals↗
PubMed1991

Stereotactic suboccipital transcerebellar biopsy under local anesthesia using the Cosman-Roberts-Wells frame. Technical note.

Previously reported suboccipital transcerebellar stereotactic biopsy methods, performed with the patient in the prone position, have required general endotracheal anesthesia. A technique is described for performing such biopsies with the patient in the lateral decubitus position, under local anesthesia. Phantom planning and routine computerized tomography graphics allow the selection of a safe entry point and intra-axial trajectory to the lesion. The time required for data acquisition and the operative procedure itself compares well with that of more routine biopsy techniques.

Anesthesia, Local↗
PubMed1991

Spinal cord stimulation: a contemporary series.

Forty-three patients with chronic pain disorders of different causes were selected for spinal cord stimulation. All underwent implantation of a ribbon electrode through a small laminotomy, under general anesthesia. Thirteen patients (30%) failed to obtain significant pain relief during a period of trial stimulation, and their electrodes were removed. The remainder underwent a definitive implant and were followed for a mean of 13 months (range, 3-33 months). Nineteen of them (63%) continued to experience pain relief. A detailed analysis of this series, as well as a literature review, is presented.

Adult↗