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Symptomatic cysts of the cavum septi pellucidi and cavum vergae: the role of endoscopic neurosurgery in the treatment of four consecutive cases.

Cavum septi pellucidi and cavum vergae are generally asymptomatic fluid collections between the leaves of the septum pellucidum and are present in approximately 15 % of adult brains. These cavities rarely enlarge and become symptomatic causing significant neurological dysfunction as a result of obstruction of the interventricular foramina, distortion of the vascular structures of the deep venous system or compression of the hypothalamoseptal triangle. The authors present a series of four patients with symptoms related directly to pressure effects from the cyst wall to the neighbouring deep brain structures. There were two females and two males with a mean age of 47.5 years. All four patients underwent endoscopic cyst fenestration with a rigid endoscope. In 2 patients frameless neuronavigation was accomplished with the optical tracking system (Radionics, Burlington, USA). All symptoms related to pressure effect resolved after surgery. Endoscopic pellucidotomy of symptomatic cysts of the septum pellucidum produces immediate relief of the mass effect of the cyst and resolution of associated symptoms. Additionally, frameless neuronavigation is a useful tool in planning and realizing the approach and improving intraoperative orientation.

Adult↗

Intraoperative imaging using a mobile computed tomography scanner.

OBJECTIVE: The radicality of tumour removal in patients suffering from glioma is discussed to be an important factor for longer survival times. Therefore intraoperative imaging modalities like magnetic resonance imaging (MRI), computed tomography (CT) and ultrasound (US) are tested in many neurosurgical facilities for clinical use. In our department a mobile CT for intraoperative applications is used for this purpose since 1999. The handling and useful application of the mobile CT scanner as well as results without intraoperative imaging are discussed. MATERIAL AND METHODS: 470 CT scans with the mobile CT were accomplished, including 270 cases of neuronavigation planning, 76 cases of intraoperative scans, 48 cases of postoperative scans, 69 CT scans for stereotactic biopsy planning and control as well as 3 cases of emergency scanning in trauma patients and 4 spine applications. The results of the intraoperative CT scans are compared with those of the postoperative MRI scans. Additionally 87 patients with glioma were evaluated. These patients underwent surgery without intraoperative imaging. RESULTS: In 27 out of 43 patients with glioma residual tumour was detected with intraoperative CT. In 13 cases the surgery was resumed to complete resection, in 14 cases the operation was not continued due to close vicinity to eloquent areas or difficulties in image interpretation. In 44 cases the results of intraoperative CT and postoperative MRI were compared. In 6 cases the MRI demonstrated residual tumour in contrast to the results of the CT scans. In 3 cases the tumour removal could have been more complete (6.8 %). In 87 cases glioma surgery was performed without intraoperative CT. In 6 cases a more complete tumour removal could have been performed (6.9 %) according to the results of postoperative MRI. CONCLUSION: Intraoperative imaging with a mobile CT scanner is a good method for detection of residual tumour. The CT scanner can be integrated in an operative setting without problems. Although intraoperative imaging can be helpful in some selected cases, most of the neurosurgical procedures can be well performed with proper neuronavigation planning.

Brain Neoplasms↗

[Low frequency repetitive transcranial magnetic stimulation (rTMS) for the treatment of chronic tinnitus--are there long-term effects?].

OBJECTIVE: Clinical, neurophysiological and neuroimaging data suggest that chronic tinnitus resembles neuropsychiatric syndromes characterised by focal brain activation. Low frequency repetitive transcranial magnetic stimulation (rTMS) has been proposed as an efficient method in treating brain hyperexcitability disorders. METHODS: Patients suffering from chronic tinnitus underwent a [ (18)F]deoxyglucose-PET (positron emission tomography). Fusioning of the individual PET scan with the structural MRI-scan (magnetic resonance imaging, T1, MPRAGE) revealed an increased metabolic activation in the primary auditory cortex as target point for rTMS. A neuronavigational system enabled the positioning of the figure of eight coil in relation to the target area. rTMS (110 % motor threshold; 1 Hz; 2000 stimuli/day over 5 days) was performed using a placebo controlled cross-over design. RESULTS: Following active rTMS there was a moderate improvement of tinnitus perception. Treatment effects lasted up to six months in some patients. CONCLUSIONS: Neuronavigated rTMS offers new possibilities in the understanding and treatment of chronic tinnitus.

Adult↗

Image-guided motor cortex stimulation in patients with central pain.

According to recent clinical data, motor cortex stimulation (MCS) is an alternative treatment for central pain syndromes. We present our minimally invasive technique of image guidance for the placement of the motor cortex-stimulating electrode and assess the clinical usefulness of both neuronavigation and vacuum headrest. Five patients suffering from central pain underwent MCS with the guidance of a frameless stereotactic system (BrainLab AG, Munich, Germany). The neuronavigation was used for identification of the precentral gyrus and accurate planning of the single burr hole. The exact location was reconfirmed by an intraoperative stimulation test. Postoperative clinical and neuroradiological evaluations were performed in each patient. The navigation system worked properly in all 5 neurosurgical cases. Determination of the placement of stimulating electrode was possible in every case. All patients obtained postoperative pain relief. No surgical complication occurred, and the postoperative course was uneventful in all patients. This preliminary experience may confirm image guidance as a useful tool for the surgery of MCS. Additionally, minimal and safe exposure can be achieved using a single burr hole and vacuum headrest.

Aged↗

Application of intraoperative 3D ultrasound during navigated tumor resection.

Intraoperative 3D ultrasound (3D-iUS) may enhance the quality of neuronavigation by adding information about brain shift and tumor remnants. The aim of our study was to prove the concept of 3D ultrasound on the basis of technical and human effects. A 3D-ultrasound navigation system consisting of a standard personal computer containing a video grabber card in combination with an optical tracking system (NDI Polaris) and a standard ultrasound device (Siemens Omnia) with a 7.5 MHz probe was used. 3D-iUS datasets were acquired after craniotomy, at different subsequent times of the procedure and overlaid with preoperative MRI. All patients underwent early postoperative 3D MRI including contrast agent within 24 hours after surgery. Acquisition of 3D iUS and the fusion with preoperative MRI was successful in 22/23 patients. The expenditure of time was at least 5 minutes for one intraoperative 3D US dataset. The technique was used three to seven times during surgery. The quality of the ultrasound images was superior in cases of metastasis, meningeoma and angioma over those in malignant glioma. Brain shifting ranged from 2-25 mm depending on localization and kind of tumor. A resection control was possible in 78%. All six neurosurgeons demonstrated a learning curve. The introduction of 3D ultrasound has increased the value of neuronavigation substantially, making it possible to update several times during surgery and minimize the problem of brain shift. Configuration of both the 3D iUS based on a standard ultrasound system and the MR navigation system is time- and especially cost-effective. Faster navigational datasets and more intuitive image-guided surgery enable novel and user-friendly display techniques.

Adult↗

Intraoperative high-field-strength MR imaging: implementation and experience in 200 patients.

PURPOSE: To review the initial clinical experience with intraoperative high-field-strength magnetic resonance (MR) imaging of brain lesions in 200 patients. MATERIALS AND METHODS: Two hundred patients (mean age, 46.1 years; range, 7-84 years), most of whom had glioma or pituitary adenoma, were examined with a 1.5-T MR imager equipped with a rotating operating table and located in a radiofrequency-shielded operating theater. A navigation microscope placed inside the 0.5-mT zone and used in combination with a ceiling-mounted navigation system enabled integrated microscope-based neuronavigation. The extent of resection depicted at intraoperative imaging, the surgical consequences of intraoperative imaging, and the clinical practicability of the operating room setup were analyzed. RESULTS: Seventy-seven resections with a transsphenoidal approach, 100 craniotomies, and 23 burr-hole procedures were performed. In 55 (27.5%) of 200 patients, intraoperative MR imaging had immediate surgical consequences (eg, extension of resection in 39% of patients with pituitary adenoma or glioma). In 108 patients the navigation system was used, and for 37 of those patients, functional imaging data were integrated into the navigation system. There was nearly no difference in quality between pre- and intraoperative images. Intraoperative workflow with intraoperative patient transport for imaging was straightforward, and imaging in most cases began less than 2 minutes after sterile covering of the surgical site. No complications resulted from high-field-strength MR imaging. CONCLUSION: The high-field-strength MR imager was successfully adapted for intraoperative use with the integrated neuronavigation system. Intraoperative MR imaging provided valuable information that allowed intraoperative modification of the surgical strategy.

Adenoma↗

Intracranial navigation using a novel device for endoscope fixation and targeting: technical innovation.

Intracranial endoscopy involves point-to-point navigation: first, in the introduction of the endoscope into a cerebrospinal fluid-containing space and, second, in the identification of a target structure. We report testing and preliminary clinical use of a device for the direct cranial fixation and point-to-point neuronavigation of a rigid ventricular endoscope. An 18-month-old female child presented with rapidly progressive macrocephaly, developmental delay and left hemiparesis. Neuroimaging revealed a large suprasellar cyst and obstructive hydrocephalus. We adapted a ball-stem device with an endoscopic working channel for direct cranial fixation over a burr hole. This device was successfully used in conjunction with MR-based neuronavigation to fenestrate the cyst. Seven months after the operation her developmental delay, macrocephaly and hemiparesis resolved. This device may be particularly effective in cases of small ventricles, ambiguous intra-ventricular landmarks, and in children too young for head-holder immobilization.

Arachnoid Cysts↗

Language functional magnetic resonance imaging in preoperative assessment of language areas: correlation with direct cortical stimulation.

OBJECTIVE: The aim of this study was to analyze the usefulness of preoperative language functional magnetic resonance imaging (fMRI), by correlating fMRI data with intraoperative cortical stimulation results for patients with brain tumors. METHODS: Naming and verb generation tasks were used, separately or in combination, for 14 right-handed patients with tumors in the left hemisphere. fMRI data obtained were analyzed with SPM software, with two standard analysis thresholds (P < 0.005 and then P < 0.05). The fMRI data were then registered in a frameless stereotactic neuronavigational device and correlated with direct brain mapping results. We used a statistical model with the fMRI information as a predictor, spatially correlating each intraoperatively mapped cortical site with fMRI data integrated in the neuronavigational system (site-by-site correlation). Eight patients were also studied with language fMRI postoperatively, with the same acquisition protocol. RESULTS: We observed high variability in signal extents and locations among patients with both tasks. The activated areas were located mainly in the left hemisphere in the middle and inferior frontal gyri (F2 and F3), the superior and middle temporal gyri (T1 and T2), and the supramarginal and angular gyri. A total of 426 cortical sites were tested for each task among the 14 patients. In frontal and temporoparietal areas, poor sensitivity of the fMRI technique was observed for the naming and verb generation tasks (22 and 36%, respectively) with P < 0.005 as the analysis threshold. Although not perfect, the specificity of the fMRI technique was good in all conditions (97% for the naming task and 98% for the verb generation task). Better correlation (sensitivity, 59%; specificity, 97%) was achieved by combining the two fMRI tasks. Variation of the analysis threshold to P < 0.05 increased the sensitivity to 66% while decreasing the specificity to 91%. Postoperative fMRI data (for the cortical brain areas studied intraoperatively) were in accordance with brain mapping results for six of eight patients. Complete agreement between pre- and postoperative fMRI studies and direct brain mapping results was observed for only three of eight patients. CONCLUSION: With the paradigms and analysis thresholds used in this study, language fMRI data obtained with naming or verb generation tasks, before and after surgery, were imperfectly correlated with intraoperative brain mapping results. A better correlation could be obtained by combining the fMRI tasks. The overall results of this study demonstrated that language fMRI could not be used to make critical surgical decisions in the absence of direct brain mapping. Other acquisition protocols are required for evaluation of the potential role of language fMRI in the accurate detection of essential cortical language areas.

Adolescent↗

Endoscopic anatomic features of the triangular recess.

OBJECTIVE: To describe the morphological and topographic features of the triangular recess (TR) in the anterior wall of the third ventricle and the pathological conditions that allow its observation during ventricular endoscopic neuronavigation. METHODS: A systematic review of records and operative videotapes for 145 patients who underwent endoscopic third ventriculostomy was performed. RESULTS: The TR could be recognized in five cases of hydrocephalus, each caused by a different underlying pathological condition. The approach was precoronal in four cases and suboccipital in one. The morphological and topographic features of the TR and adjacent structures varied among the different cases. CONCLUSION: Although it is seldom reported in neuroanatomy handbooks and is not readily accessible under normal conditions, the TR is a characteristic structure of the third ventricle, which might become apparent in several conditions that produce hydrocephalus. Neurosurgeons who perform neuroendoscopy should be aware of this structure and of the situations that cause its deformation and allow its observation during endoscopic neuronavigation.

Adult↗

Implementation of fiber tract navigation.

OBJECTIVE: To implement fiber tracking in a common neuronavigation environment for routine clinical use to visualize major white matter tracts intraoperatively. METHODS: A single-shot, spin-echo diffusion weighted echo planar imaging sequence with six diffusion directions on a 1.5 T magnetic resonance scanner was used for diffusion tensor imaging. For three-dimensional (3-D) tractography, we applied a knowledge-based multiple volume of interest approach. Tracking was initiated in each voxel of the initial seed volume in retrograde and orthograde directions according to the direction of the major eigenvector by applying a tensor deflection algorithm. Tractography results were displayed as streamlines assigned direction encoding color. After selecting the fiber tract bundle of interest by defining inclusion and exclusion volumes, a 3-D object was generated automatically by wrapping the whole fiber tract bundle. This 3-D object was displayed along with other contours representing tumor outline and further functional data with the microscope heads-up display. RESULTS: In 16 patients (three cavernomas, 13 gliomas), major white matter tracts (pyramidal tract, n = 14; optic radiation, n = 2) were visualized intraoperatively with a standard navigation system. Three patients developed a postoperative paresis, which resolved in two in the postoperative course. Additional planning time for tractography amounted to up to 10 minutes. Comparing the tractography results with a fiber bundle generated on a different platform by applying a distortion-free sequence revealed a good congruency of the defined 3-D outlines in the area of interest. CONCLUSION: Fiber tract data can be reliably integrated into a standard neuronavigation system, allowing for intraoperative visualization and localization of major white matter tracts such as the pyramidal tract or optic radiation.

Adolescent↗

Simultaneous image-guided and endoscopic navigation without rigid cranial fixation: application in infants: technical case report.

OBJECTIVE AND IMPORTANCE: Infants and young children demonstrate a variety of intraventricular and periventricular lesions. Endoscopy has proven useful in the treatment of many of these lesions, but its benefit is limited if it is applied to complex loculated cysts or if the disease is concealed by normal ependymal boundaries. In adults and older children, endoscopy can be augmented by the simultaneous use of frameless stereotaxy, but this combined modality has not been possible in infants and young children without rigid cranial fixation. We describe a method of achieving simultaneous stereotactic and endoscopic navigation in infants and young children by using a pinless, frameless stereotactic assembly. CLINICAL PRESENTATION: The first patient was a 6-week-old boy with macrocephaly and a bulging fontanelle. Computed tomographic and magnetic resonance imaging revealed a complex arachnoid cyst and obstructive hydrocephalus. The second patient was a 7-month-old, ex-premature (27-wk gestational age) boy who developed posthemorrhagic hydrocephalus. He underwent multiple shunt revisions, one of which was complicated by enterococcal ventriculitis. Despite bilateral ventriculoperitoneal shunts, he developed increasing head circumference, listlessness, and irritability. Imaging revealed an enlarged, multiloculated, and asymmetric ventricular system. INTERVENTION: Simultaneous image-guided and endoscopic neuronavigation was implemented in both patients. Before the procedure, a cranial reference arc was secured to the outer table of the cranium through a small incision adjacent to the operative field. After the stereotactic apparatus was registered, the software was used to plan a trajectory for the approach. A burr hole was then made, and a rigid 6-mm endoscope was inserted for direct visualization. Once advanced past the endoscopic port tip, the electromagnetic coil stylet was used to stereotactically track position and identify areas for fenestration, biopsy, and catheter insertion. CONCLUSION: Endoscopic views of complex hydrocephalus and arachnoid cysts alone are often difficult to interpret. Simultaneous image-guided and endoscopic neuronavigation may be advantageous in the management of complex cases that are anatomically related to the ventricular system in infants for whom rigid cranial fixation could lead to increased procedure-related morbidity.

Brain Diseases↗

Frameless stereotactic surgery using intraoperative high-field magnetic resonance imaging.

This study evaluated the clinical validity of frameless stereotaxy using high-field intraoperative magnetic resonance (iMR) imaging combined with an in-room neuronavigation system. A 1.5 Tesla MR scanner in conjunction with a ceiling-mounted neuronavigation system was used during 32 frameless stereotaxy procedures consisting of 19 brain biopsies and 13 catheter placements between April 2002 and mid-October 2003. Evaluation of the procedure was based on either the rate of histological diagnostic yield or the ability to accurately position the catheter in the target region. This technique allowed successful registration with a mean error of 1.2 +/- 0.8 mm and resulted in successful placement of the instrument within the target tissue. Intraoperatively, frozen section analysis showed all biopsy samples contained pathological tissue and locations of sampling points were confirmed by iMR imaging. Specific final diagnosis was made in all 19 brain biopsies. The tip of the catheter was successfully placed into the target in all 13 patients confirmed by iMR imaging. The catheter was repositioned based on iMR imaging in four of 13 patients, increasing the rate of successful placement. There were no procedure-related neurological deficits or mortality, but we encountered two cases of wound infection, one needing surgical revision. Total additional procedure time related to the induction of iMR imaging was 76.7 +/- 23.3 minutes. This initial experience of the combination of conventional frameless stereotaxy and high-field iMR imaging improved the quality of frameless stereotaxy with low morbidity and mortality, but did not translate into a significant reduction of procedure-related time.

Adolescent↗

Resection of a left insular cavernoma aided by a simple navigational tool. Technical note.

The management of cavernous malformations of the brain is markedly influenced by the location of the lesions themselves. In the last decade, resection of cavernomas arising in the dominant insular lobe has been deemed safe only with the guidance of neuronavigation. Most navigation equipment, however, shares some minor drawbacks, including costs, longer operating time, and a variable loss of accuracy due to intraoperative brain shift. In this paper the authors present the case of a left dominant insular cavernoma that was successfully removed using a novel form of navigation that they call magnetic resonance imaging-based corticotopography. This technique, which is unaffected by the brain shift phenomenon, provided a simple and inexpensive alternative to standard neuronavigation. Selected cases of subcortical brain lesions could be conveniently approached using the same technique.

Adult↗

Intracranial navigation by using low-field intraoperative magnetic resonance imaging: preliminary experience.

OBJECT: Intracranial navigation by using intraoperative magnetic resonance (iMR) imaging allows the surgeon to reassess anatomical relationships in near-real time during brain tumor surgery. The authors report their initial experience with a novel neuronavigation system coupled to a low-field iMR imaging system. METHODS: Between October 2000 and December 2001, 70 neurosurgical procedures were performed using the mobile 0.12-tesla PoleStar N-10 iMR imaging system. The cases included 38 craniotomies, 15 brain biopsies, nine transsphenoidal approaches, and one drainage of a subdural hematoma. Tumor resection was performed using the awake method in seven of 38 cases. Of the craniotomies, image-confirmed complete or radical tumor resection was achieved in 28 cases, subtotal resection in eight cases, and open biopsies in two cases. Tumor resection was controlled with the use of image guidance until the final intraoperative images demonstrated that there was no residual tumor or that no critical brain tissue was at risk of compromise. In each stereotactic biopsy the location of the biopsy needle could be verified by intraoperative imaging and diagnostic tissue was obtained. Complications included a case of aseptic meningitis after a biopsy and one case of temporary intraoperative failure of the anesthesia machine. Awake craniotomies were performed successfully with no permanent neurological complications. CONCLUSIONS: Intraoperative MR image-based neuronavigation is feasible when using the Odin PoleStar N-10 system for tumor resections that require multiple other surgical adjuncts including awake procedures, cortical mapping, monitoring of somatosensory evoked potentials, or electrocorticography. Use of the system for brain biopsies offers the opportunity of immediate verification of the needle tip location. Standard neurosurgical drills, microscopes, and other equipment can be used safely in conjunction with this iMR imaging system.

Adult↗

Navigated laser-assisted endoscopic fenestration of a suprasellar arachnoid cyst in a 2-year-old child with bobble-head doll syndrome. Case report.

The authors present the case of a 2-year-old boy with bobble-head doll syndrome (BHDS) associated with a large suprasellar arachnoid cyst and enlarged ventricles, who was successfully treated with neuronavigated laser-assisted endoscopic ventriculocystocisternostomy. The clinical history, surgical treatment, and clinical follow up of the patient are described. A navigated laser-assisted endoscopic ventriculocystocisternostomy of the suprasellar arachnoid cyst led to cessation of the head bobbing, and notable reduction of the cyst and ventricles was visible on the postoperative magnetic resonance images. Caused by a suprasellar arachnoid cyst, BHDS can be successfully treated with navigated laser-assisted endoscopic ventriculocystocisternostomy. The advantages of this procedure are minimal invasiveness and facilitated guidance of the neuronavigation system to the target area when normal anatomical landmarks are not visible.

Arachnoid Cysts↗

Frameless, pinless stereotactic neurosurgery in children.

OBJECT: Frameless neuronavigation has been established as a useful adjunct to intracranial surgery; however, the procedure is limited in young children by the need for rigid skull fixation with pins. Pin fixation is difficult and hazardous for patients younger than 2 years of age. Minor risks have been associated with pin fixation in older patients also, including scalp laceration, skull fracture, and epidural hematoma. METHODS: The authors adapted a pinless head fixation system, consisting of a beanbag device, for use with frameless neuronavigation. This system was used to perform intracranial neurosurgical procedures in nine patients. CONCLUSIONS: This pinless, frameless method provides a new option for children who are unable to sustain rigid head fixation. It is also an alternative to rigid pin fixation for patients of any age.

Adolescent↗

Three-dimensional ultrasonography navigation in spinal cord tumor surgery. Technical note.

The authors describe the technical application of three-dimensional (3D) ultrasonography navigation in spinal cord tumor surgery. The spinal cord is a complex neurological structure in which there is the potential for causing neurological morbidity during tumor resection. Standard neuronavigation systems based on computed tomography or C-arm images are not adapted to tumor surgery in the spinal cord. Since 2004 the authors have been using a 3D ultrasonography-based neuronavigation system. During surgery, two-dimensional ultrasound images were acquired and reconstructed into 3D image data to assist in tumor resection. The navigation cameras read the position of a patient reference frame attached to a spinous process, the ultrasonography probe, and surgical instruments. Five- and 10-MHz phased-array ultrasonography probes equipped with optical tracking frames were used for image data acquisition. Spinal cord tumors were visualized using ultrasonography, and 3D ultrasonography-guided tumor biopsy sampling and resection were performed. The practice of attaching the reference frame to a spinous process adjacent to the spinal cord tumor, as well as performing image acquisition just before starting the resection, reduced the possible sources of inaccuracy. The technical application of a navigation system based on intraoperative 3D ultrasound image reconstruction seems feasible and may have the potential of improving functional outcome in association with spinal cord tumor surgery.

Adult↗

Robot-assisted navigated neuroendoscopy.

OBJECTIVE: Major steps in the evolution of advanced neurosurgical techniques include microneurosurgery, neuroendoscopy and its minimally invasive variations, neuronavigation, and advanced intraoperative imaging. With traditional neuroendoscopic techniques (e.g., freehand endoscopy or the use of mechanical arms), definitive controlled movement of the endoscope within the brain depends on the experience and skill of the individual neurosurgeon. METHODS: With the Evolution 1 precision robot (Universal Robot Systems, Schwerin, Germany), a new neurosurgical tool has become available for the precise steering of instruments within the cranium. After preclinical anatomic and precision studies, the system was used for neuronavigated endoscopic procedures for three patients. RESULTS: All robot-assisted, navigated, endoscopic procedures were successfully completed. The time for the registration procedure and setup of the robot decreased from 60 minutes for the first patient to 30 minutes for the third patient. The time for the surgical part of the endoscopic procedure ranged from 17 to 65 minutes. No complications occurred during any procedure. CONCLUSION: The use of robotic technology for neuroendoscopic procedures is a major advance for controlled movement of the endoscope within the cranium. The start-up procedure and calibration of the robot are still time-consuming, but the actual operation time is comparable to that of freehand neuroendoscopic procedures. Steering of the endoscope is facilitated, and the precision of the endoscopic movements is noteworthy.

Adolescent↗