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At least 685 records · Page 38Linked to original sources
PubMed2006

Direct anatomical localization of the subthalamic nucleus on CT with comparison to Schaltenbrand-Wahren atlas.

Stimulation of the subthalamic nucleus (STN) has become an accepted treatment for motor symptoms of Parkinson's disease. Generally, localization of the target is based on stereotactic atlas coordinates and magnetic resonance (MR) images. In this paper a method of direct anatomical localization of the STN on computed tomography (CT) images is described and compared with the Schaltenbrand-Wahren atlas. Serial CT scans were obtained at 1.5-mm interval and scan thickness of 3 mm, with the CT gantry and glabella-inion plane of the patient's head vertical. The STN was identified as a dense structure medial to the inner semicircular border of the internal capsule in the subthalamic region. Its visibility was increased by changing the window and level settings on the CT workstation computer. The center of the STN in relationship to the intercommissural line, determined by this technique, was similar to those found on standard atlases.

Adult↗
PubMed2006

A simple stereotactic method for frameless deep brain stimulation.

BACKGROUND: Deep brain stimulation (DBS) is widely used to treat advanced Parkinson's disease, other movement and psychiatric disorders. DBS implantation requires application of a stereotactic frame throughout a lengthy procedure, making it uncomfortable and tiring. We designed a stereotactic cube to stage the operation, perform frameless microelectrode recording (MER) and fix the DBS. METHODS: The 15-mm cube is implanted in a burr hole using bone cement. It contains 5 parallel trajectories (central + 4 around). It is aligned by stereotactic frame so that central trajectory reaches the target. Frameless MER is performed by attaching a micro-driver to the cube using 2-5 cannulae (4 cm). The DBS is fixed to the cube by a mini-plate and 1 screw. Ninety-six cubes were compared with 43 Bennet spheres (BS). RESULTS: No cube moved compared to 2 (5%) BS (p < 0.05). The final trajectory was central in 64.4% of cubes compared to 47.5% of BS, and the final target was >2 mm out in no cubes compared to 12.5% of BS (p < 0.01). Infection and haemorrhage were observed in 2.5% and 3.3% of cubes, respectively, while 5% of BS developed infection, 5% haemorrhage and 7.5% skin erosion. CONCLUSIONS: This method is simple and effective in staging DBS procedures, performing frameless MER and DBS implantation, fixation and revision.

Adult↗
PubMed2006

Stereotactic accuracy of a compact intraoperative MRI system.

OBJECTIVE: To analyze the stereotactic accuracy of the PoleStar N-20, a compact intraoperative magnetic resonance imaging (iMRI) system, based on a 0.15-Tesla (T) magnet. METHODS: An MRI-compatible phantom was scanned after being positioned in both the center of the magnetic field (COF) and the periphery of the field (POF) of the PoleStar N-20 magnet. Scans were acquired at various slice thicknesses in 3 sequences: T(1) weighted, T(2) weighted and Esteady (reversed fast imaging with steady-state precession, also known as 'PSIF'). The distance between the actual location of the probe tip in space and the location of the target on the image was measured on the axial, coronal, and sagittal planes for 9 points on each image. Each measurement was repeated 3 times. We also compared the structural features of the PoleStar N-20 to those of its predecessor. RESULTS: T(1)-weighted scans yielded the most accurate measurements. There was no statistically significant difference between scans acquired at thicknesses of 2, 3, 4 and 8 mm; all were accurate for clinical purposes. Comparison of COF with POF measurements using T(1)-weighted scans did not demonstrate a statistically significant difference in accuracy. CONCLUSIONS: The PoleStar N-20 0.15-T iMRI system provides surgical navigation that is at least as accurate as the first generation model of this system, which employed a 0.12-T magnet. Further analysis of stereotactic accuracy on clinical cases using the PoleStar N-20 is needed to confirm that these results will bear out in surgical reality.

Equipment Design↗
PubMed2006

Application accuracy of an electromagnetic field-based image-guided navigation system.

OBJECTIVE: We tested the application accuracy of an electromagnetic field-based image guidance system to compare it to traditional optically tracked systems. METHODS: A plastic skull phantom was fitted with fiducial markers rigidly attached via self-drilling bone screws. Volumetric CT scan was obtained to simulate the clinical condition. A metal disc marked in 1-mm increments was placed at the expected target point. Following registration and alignment of a trajectory guide, radial and depth localization errors were measured after both freehand and stabilized approaches on both the right and left sides. Statistical analyses of the localization errors were performed. RESULTS: Total target localization error ranged from 0.71 to 3.51 mm with a mean +/- SEM of 2.13 +/- 0.11 mm. The radial error averaged 0.98 +/- 0.11 mm, depth error 1.74 +/- 0.13 mm. The freehand procedures produced a statistically greater radial, depth and total error than the fixed procedures. CONCLUSIONS: Accuracy of image-guided localization using an electromagnetic field guidance system is similar to that reported for optically guided systems.

Diagnostic Imaging↗
PubMed2006

Image-guided radiosurgical ablation of intra- and extra-cranial lesions.

For decades since its introduction, stereotactic radiosurgery (SRS) was used only to treat intracranial lesions because intracranial targets could be immobilized and located relative to a rigid metal frame affixed to the patient's head. Lesions outside the head were generally not treated with SRS because it is difficult to immobilize extracranial lesions and to attach stereotactic frames elsewhere on the body. Advances in computerized image guidance and robotics allowed the development of systems, such as the CyberKnife SRS System (Accuray, Inc, Sunnyvale, CA), that could target intracranial lesions without the stereotactic frame. Enhancements have resulted in a radiation delivery system that can accurately deliver high-dose, focal radiation to lesions in the spine, chest, and abdomen, even if they move during respiration. In this review we will describe the technical features of frameless SRS systems and briefly review their application to treating intracranial and extracranial lesions, focusing in particular on spinal lesions.

Brain Neoplasms↗
PubMed2003

Chronic motor cortex stimulation for movement disorders: a promising perspective.

Five patients affected by thalamic hand and international myoclonus have been evaluated and selected for chronic motor cortex stimulation. A quadripolar electrode strip was placed epidurally under local anesthesia through an MR-image-guided single precentral burr hole placed following the morphologic recognition of the central sulcus. Intra-operative stimulation was used to induce muscle contraction at the affected site to confirm the correct placement of the electrode. A one-week trial period preceded the implant of an internal pace-maker under general anesthesia. A remarkable decrease in pain was reported by four patients together with the reduction of dystonia and rigidity in thalamic hand and marked decrease of intentional myoclonus. No complications or undesired side effects of electrode implant and stimulation were observed.

Adult↗
PubMed2006

The role of the superciliary approach in the surgical management of intracranial neoplasms.

OBJECTIVE: The authors present and evaluate the experiences with 76 frontolateral keyhole craniotomies performed for supratentorial intracranial tumors via superciliary skin incisions. METHOD: The exploration is a modification of the generally used pterional approach. Out of a series of 302 cases operated on with frontolateral keyhole craniotomies via superciliary skin incisions, 76 had various tumors at the frontal base, intra-, supra-, parasellar and intraorbital regions. The operations were carried out through a approximately 2.5 x 3 cm frontolateral miniaturized craniotomy following a skin incision at the upper edge of the eyebrow. CONCLUSION: Despite the small size of craniotomy the superciliary approach is a suitable technique for resection of skull base tumors in the anterior fossa, orbit, sellar, parasellar and suprasellar regions. The exploration allows enough room for intracranial surgical manipulation with maximal protection of normal brain, vessel and nerve structures. The presented patients did not have any craniotomy-related complication.

Adolescent↗
PubMed2006

Craniotomy using image-guided oscillating saw: technical note.

OBJECTIVE: To describe a new craniotomic technique that eliminates burr holes and minimizes bone loss along the craniotomic line. PATIENTS AND METHODS: Fifty burr hole free craniotomies were performed in varied locations using an image-guided micro-oscillating saw. Care was taken to avoid cutting the inner cortical layer. Upon completing the micro-oscillating saw cut the inner table could then be gently fractured along the craniotomic line with a thin bladed osteotome. Simple silk sutures were used to resecure the bone flap. RESULTS: The craniotomic time required for this procedure ranged from 7 to 24 minutes (mean: 13 minutes). We observed no dural lacerations or signs of brain damage in any of these procedures. The use of image guidance allows a continuous measure of bone thickness along the craniotomic line. In all of the cases we report the cosmetic result was excellent. CONCLUSION: This alternative technique of craniotomy can be used in selected cases to achieve excellent cosmetic results which avoid the time and cost of complex reconstruction techniques.

Adolescent↗
PubMed2005

Diffusion tensor tractography of the motor white matter tracts in man: Current controversies and future directions.

The anatomy of the brain is extremely complex, and certain, even large structures, such as the corticospinal tract (CST), remain poorly understood. Diffusion tractography provides an opportunity to explore the white matter tracts in a fundamentally new way. In the current paper, we show how this technique has already added to our understanding of the anatomy of the CST. We also explore the future projects involving diffusion tractography of the motor white matter tracts that will advance this method and further our understanding of brain anatomy.

Brain Mapping↗
PubMed2003

Subtonsillar approach to the foramen of Luschka: an anatomic and clinical study.

OBJECTIVE: Conventional approaches to tumors of the foramen of Luschka are limited because the foramen is viewed from either the fourth ventricle laterally (transvermian approach) or the cerebellopontine angle medially (suboccipital approach). The definitive approach is subtonsillar, because the foramen of Luschka is actually the end of the natural cleavage plane between the cerebellar tonsil and the medulla. We describe the microsurgical anatomic features of the foramen of Luschka region and the operative technique for the subtonsillar approach to this region. METHODS: In the anatomic study, five formalin-fixed, silicone-injected, cadaveric heads were used. In the clinical study, the records for five patients treated via the subtonsillar approach were examined; several illustrative cases are presented. RESULTS: The foramen of Luschka is formed by the tela choroidea and the rhomboid lip and exists at the lateral end of the cerebellomedullary fissure, which is a natural cleavage plane between the cerebellar tonsil and the medulla. The subtonsillar approach is performed via a suboccipital craniotomy; the patient is positioned in the lateral decubitus position, with the tumor side down. After the cerebellar tonsil is freed from arachnoid adhesions, it can be retracted rostrodorsally from the medulla, to expose the cerebellomedullary fissure. Clinically, the tela choroidea and rhomboid lip are significantly attenuated by tumor expansion. Therefore, by dissecting in a subtonsillar manner around the tumor, one can reach the foramen of Luschka without traversing any neural tissue. CONCLUSION: The subtonsillar approach yields a panoramic view to the foramen of Luschka laterally and up to the middle cerebellar peduncle superiorly. This approach minimizes the distance between the tumor and the surgeon, while maximizing neural preservation. We think this is the definitive approach to this difficult region of the posterior fossa.

Adult↗
PubMed2003

Anatomic and neurophysiological methods for the targeting and lesioning of the subthalamic nucleus: Cuban experience and review.

OBJECTIVE: To develop a method to place a lesion precisely in the subthalamic nucleus (STN) and evaluate its effectiveness. METHODS: A retrospective study of targeting data collected during stereotactic planning to lesion the STN in 31 patients with Parkinson's disease and of results in more than 50 procedures was performed. The targeting method was based on computed tomographic imaging together with semimicroelectrode recording digital processing and electrical stimulation. Two statistical methods were used to correlate initial with final target coordinates and assess the efficacy of the targeting procedure. RESULTS: The anatomic target based on computed tomographic imaging data showed electrical activity in the subthalamus in the first pass in 82% of the procedures. In the remaining 18%, the STN was an average of 1.93 mm away from the nearest trajectory that recorded the STN (range, 1.41-2.24 mm). The average number of trajectories per procedure was 7.2; the location of the first trajectory relative to the center of the nucleus determined by electrical and physiological means (P < 0.01, analysis of variance, Student's t test) was as follows: in the lateral direction, 1.25 +/- 1.15 mm; in the anteroposterior direction, 1.53 +/- 1.31 mm; and in the vertical direction, 0.67 +/- 0.51 mm. The average number of tracts necessary to lesion the STN was two. CONCLUSION: The combination of computed tomographic imaging, semimicroelectrode recording, and microstimulation provides an effective method to identify the STN lesion in parkinsonian patients. The method used for anatomic localization and electrophysiological mapping of the subthalamus was found to be effective in reaching the sensorimotor region of the nucleus. We carried out an accurate determination of the subthalamus location and its volume in the lesioning.

Adult↗
PubMed2003

Concomitant use of computer image guidance, linear or sigmoid incisions after minimal shave, and liquid wound dressing with 2-octyl cyanoacrylate for tumor craniotomy or craniectomy: analysis of 225 consecutive surgical cases with antecedent historical control at one institution.

OBJECTIVE: Recent neurosurgical literature reflects rapidly evolving, technically enhanced methods that promise to improve neurosurgical outcomes. We review our experience with computer image guidance, linear or sigmoid incisions after minimal shaving, and liquid wound dressing with 2-octyl cyanoacrylate (Dermabond; Ethicon, Inc., Somerville, NJ) for tumor craniotomy or craniectomy in our attempt to optimize craniotomy or craniectomy for tumor. METHODS: After institutional review board approval, we retrospectively reviewed patients who underwent craniotomy or craniectomy for tumor with or without the combination of techniques specified above. A prior cohort of patients who underwent craniotomy or craniectomy with traditional techniques served as a retrospective basis of comparison. Analysis included in- and outpatient chart reviews, which included the operative notes, pathology reports, discharge summaries, outpatient office records, and intraoperative nursing records. Data were entered into a statistical spreadsheet for analysis and comparison. RESULTS: A total of 225 consecutive patients underwent a combination of less invasive techniques from July 2000 through October 2001. These patients were matched with 225 patients in a standard neurosurgical cohort that included patients who underwent operations from July 1994 through July 2000. Age, tumor type, radiation, reoperation rate, tumor location, and extent of resection were comparable for both groups. The overall wound complication rate was significantly lower in the minimally invasive group when compared with the control cohort of patients (0.9% versus 6.2%; P = 0.0298), even for early follow-up (0.9% versus 3.5%; P = 0.0427). Pedicle flap design was a variable that was significantly associated with wound complication. CONCLUSION: Modern neurosurgical techniques are beneficial for patients undergoing craniotomy or craniectomy for tumor and seem to be superior to standard techniques. Although the study is multifactorial and retrospective, this conclusion is further supported by the enhanced self-image patients have during the postoperative period.

Adult↗
PubMed2004

Intraoperative Iso-C C-arm navigation in craniospinal surgery: the first 60 cases.

OBJECTIVE: The intraoperative Iso-C C-arm (Siremobil Iso-C 3D; Siemens Medical Solutions, Erlangen, Germany) provides a unique ability to acquire and view multiplanar three-dimensional images of intraoperative anatomy. Registration for intraoperative surgical navigation may be automated, thus simplifying the operative workflow. METHODS: Iso-C C-arm intraoperative fluoroscopy acquires 100 images, each of which must be 1.8 degrees in a circumferential fashion about an "isocentric" point in space. The system generates a high-resolution isotropic three-dimensional data set that is available immediately after the 90-second C-arm rotation. The data set is ported to the image-guided workstation, registration is immediate and automated, and the surgeon can navigate with millimetric accuracy. The authors prospectively examined data from the initial 60 patients examined with the Iso-C, among whom were cases of anterior and posterior spinal instrumentation from the occiput to the sacrum. Percutaneous and minimally invasive spinal and cranial procedures were also included. RESULTS: Automated registration for image-guided navigation was attainable for anterior and posterior cases from the cranial base and entire spine. In most cases, intraoperative postprocedural imaging with the Iso-C mitigated the need for postoperative imaging. CONCLUSION: Intraoperative Iso-C three-dimensional scanning allows real-time feedback during cranial base and spinal surgery and during procedures involving instrumentation. In most cases, it obviates the need for postoperative computed tomography. Its usefulness is in its simplicity, and it can be easily adapted to the operating room workflow. When coupled with intraoperative navigation, this new technology facilitates complex neurosurgical procedures by improving the accuracy, safety, and time of surgery.

Adolescent↗
PubMed2004

Volumetric assessment of glioma removal by intraoperative high-field magnetic resonance imaging.

OBJECTIVE: To investigate the contribution of high-field intraoperative magnetic resonance imaging (iMRI) for further reduction of tumor volume in glioma surgery. METHODS: From April 2002 to June 2003, 182 neurosurgical procedures were performed with a 1.5-T magnetic resonance system. Among patients who underwent these procedures, 47 patients with gliomas (14 with World Health Organization Grade I or II glioma, and 33 with World Health Organization Grade III or IV glioma) who underwent craniotomy were investigated retrospectively. Completeness of tumor resection and volumetric analysis were assessed with intraoperative imaging data. RESULTS: Surgical procedures were influenced by iMRI in 36.2% of operations, and surgery was continued to remove residual tumor. Additional further resection significantly reduced the percentage of final tumor volume compared with first iMRI scan (6.9% +/- 10.3% versus 21.4% +/- 13.8%; P < 0.001). Percentages of final tumor volume also were significantly reduced in both low-grade (10.3% +/- 11.5% versus 25.8% +/- 16.3%; P < 0.05) and high-grade gliomas (5.4% +/- 9.9% versus 19.5% +/- 13.0%; P < 0.001). Complete resection was achieved finally in 36.2% of all patients (low-grade, 57.1%; high-grade, 27.3%). Among the 17 patients in whom complete tumor resection was achieved, 7 complete resections (41.2%) were attributable to further tumor removal after iMRI. We did not encounter unexpected events attributable to high-field iMRI, and standard neurosurgical equipment could be used safely. CONCLUSION: Despite extended resections, introduction of high-field iMRI in conjunction with functional navigation did not translate into an increased risk of postoperative deficits. The use of high-field iMRI increased radicality in glioma surgery without additional morbidity.

Adolescent↗
PubMed2004

Experimental radiobiological investigations into radiosurgery: present understanding and future directions.

LARS LEKSELL BEGAN radiobiological investigations to study the effect of high-dose focused radiation on the central nervous system more than 5 decades ago. Although the effects of radiosurgery on the brain tumor microenvironment are still under investigation, radiosurgery has become a preferred management modality for many intracranial tumors and vascular malformations. The effects and the pathogenesis of biological effects after radiosurgery may be unique. The need for basic research concerning the radiobiological effects of high-dose, single-fraction, ionizing radiation on nervous system tissue is crucial. Information from those studies would be useful in devising strategies to avoid, prevent, or ameliorate damage to normal tissue without compromising treatment efficacy. The development of future applications of radiosurgery will depend on an increase in our understanding of the radiobiology of radiosurgery, which in turn will affect the efficacy of treatment. This article analyzes the current state of radiosurgery research with regard to the nature of central nervous system effects, the techniques developed to increase therapeutic efficacy, investigations into the use of radiosurgery for functional disorders, radiosurgery as a tool for investigations into basic central nervous system biology, and the additional areas that require further investigation.

Animals↗
PubMed2004

On-line flow cytometry for real-time surgical guidance.

OBJECTIVE: This study tests the feasibility of using on-line analysis of tissue during surgical resection of brain tumors to provide biologically relevant information in a clinically relevant time frame to augment surgical decision making. For the purposes of establishing feasibility, we used measurement of deoxyribonucleic acid (DNA) content as the end point for analysis. METHODS: We investigated the feasibility of interfacing an ultrasonic aspiration (USA) system with a flow cytometer (FC) capable of analyzing DNA content (DNA-FC). The sampling system design, tissue preparation requirements, and time requirements for each step of the on-line analysis system were determined using fresh beef brain tissue samples. We also compared DNA-FC measurements in 28 nonneoplastic human brain samples with DNA-FC measurements in specimens of 11 glioma patients obtained from central tumor regions and surgical margins after macroscopically gross total tumor removal to estimate the potential for analysis of a biological marker to influence surgical decision making. RESULTS: With minimal modification, modern FC systems are fully capable of real-time, intraoperative analysis of USA specimens. The total time required for on-line analysis of USA specimens varies between 36 and 63 seconds; this time includes delivery from the tip of the USA to complete analysis of the specimen. Approximately 60% of this time is required for equilibration of the DNA stain. When compared with values for nonneoplastic human brain samples, 50% of samples (10 of 20) from macroscopically normal glioma surgical margins contained DNA-FC abnormalities potentially indicating residual tumor. CONCLUSION: With an interface of existing technologies, DNA content of brain tissue samples can be analyzed in a meaningful time frame that has the potential to provide real-time information for surgical guidance. The identification of DNA content abnormalities in macroscopically normal tumor resection margins by DNA-FC supports the practical potential for on-line analysis of a tumor marker to guide surgical resections. The development of such a device would provide neurosurgeons with an objective method for intraoperative analysis of a clinically relevant biological parameter that can be measured in real time.

Aneuploidy↗
PubMed2005

Frameless stereotaxy to facilitate anterolateral thoracolumbar surgery: technique.

With the advent of frameless stereotaxy and its application to the spine, more precise and less invasive spinal procedures are possible. In addition to being less invasive, these techniques may increase surgeon confidence and allow shorter operating times. Described here is a case of Pott's disease of the thoracolumbar spine and how intraoperative image guidance can facilitate operative progress and accuracy in a patient in whom the underlying disease has severely deformed the normal anatomy of the spine. Added confidence about the location of vital structures as the surgeon proceeds with resection of the vertebral bodies and discs is depicted. Facilitation with image-guided placement of bicortical vertebral body screws and an interbody device is demonstrated. A diagram of the recommended positioning of the equipment in the operating room is provided along with "pearls" learned from our experience with this application. We believe that even the most experienced and skilled surgeon will find facilitation of anterior thoracolumbar surgery with image guidance to be of considerable benefit.

Back Pain↗