Biomedical subjects

J Burtscher

Publications and source records attributed to J Burtscher.

11 recordsLinked to original sources

PubMed2003

Neuroendoscopy based on computer assisted adjustment of the endoscope holder in the laboratory.

OBJECTIVE: We present our initial clinical experience with a novel technique of frameless stereotactic neuroendoscopy using a neuronavigation system, a specially designed aiming device (endoscope holder/targeting device) combined with a vacuum-mouthpiece based head holder. Due to the reproducibility of patient immobilization in the fixation system, the endoscope holder can be adjusted in the laboratory in the absence of the patient. METHODS: An individual vacuum-mouthpiece was fabricated. The patients were scanned with an external reference frame attached to this mouthpiece and the images were transferred to the neuronavigation system. Determination of the path, mouthpiece-based registration and adjustment of the targeting device were performed the day before surgery in the absence of the patient. In the OR the patient was repositioned and the endoscope was introduced through the preadjusted aiming device to the precalculated depth. RESULTS: The novel technique was successfully used for frameless endoscopic navigation in five patients. Three endoscopic third ventriculostomies in adults, one endoscopic septostomy due to unilateral hydrocephalus in an adult female patient and one endoscopic ventriculo-cysto cisternostomy in a 20-month-old girl with a suprasellar arachnoid cyst, were performed with excellent clinical results and without technical complications. CONCLUSION: Our initial experience indicates that frameless stereotaxy, in combination with a relocatable head holder and a special targeting device, allows for precise and preplanned advancement of the neuroendoscope, reducing or even eliminating intraoperative registration and endoscope trajectory adjustments, thus substantially reducing OR time. Due to the non-invasive but rigid immobilization method, neuronavigation can also be performed in children under 2 years of age.

Adult↗

PubMed2003

Effect of endoscopic third ventriculostomy on neuropsychological outcome in late onset idiopathic aqueduct stenosis: a prospective study.

OBJECTIVE: To undertake a prospective study of the long term neuropsychological outcome in patients with late onset idiopathic aqueduct stenosis (LIAS) after endoscopic third ventriculostomy. METHODS: Six patients with LIAS were evaluated pre- and postoperatively using magnetic resonance imaging (MRI) and standardised psychometric testing procedures. Endoscopic third ventriculostomy was done using standard surgical techniques. The mean long term follow up was 81.2 weeks. RESULTS: Preoperatively, all patients had cognitive impairment, four of them showing deficits in several cognitive domains. After endoscopic third ventriculostomy, all patients improved clinically and had ventricular size reduction on MRI. Postoperative neuropsychological testing showed that five patients achieved normal or near normal cognitive functions, and one improved moderately. CONCLUSIONS: Endoscopic third ventriculostomy caused a substantial improvement in the neuropsychological deficit of LIAS patients. This was also true for patients with enlarged ventricles that might be diagnosed radiologically as "arrested hydrocephalus."

Adult↗

PubMed2002

Use of neuronavigation and electrophysiology in surgery of subcortically located lesions in the sensorimotor strip.

OBJECTIVES: Subcortical lesions in the sensorimotor strip are often considered to be inoperable. The purpose of this study was to evaluate the usefulness of a combined approach for surgery in this region, aided by a robotic neuronavigation system under electrophysiological control. METHODS: In a prospective study on 10 patients, space occupying lesions in the sensorimotor central area were removed using the Surgiscope robotic navigation system and the Nicolet Viking IV electrophysiological system. RESULTS: Precise tumour localisation with the neuronavigation system and the information on the patient's cortical motor distribution obtained by bipolar cortical stimulation led to postoperative improvement in motor function in all but one patient. Seven of the patients had focal, defined pathology (four metastases; two cavernoma; one aspergilloma). CONCLUSION: Due to the implementation of two recent technologies, surgery of lesions in the subcortical sensorimotor region can be performed with greater confidence.

Adult↗

PubMed2001

Surgery of lesions in the motor strip combining a stereotactically-guided mini-craniotomy with electrophysiological mapping of the motor cortex.

The removal of space-occupying lesions in the sensori-motor cortex carries a considerable risk of postoperative palsy. Therefore subcortical lesions located in the sensori-motor strip are often considered to be inoperable. Treatment options are stereotactic biopsy and radiosurgery beside radiological control examinations without surgery or surgery with a higher risk of postoperative deficits. The following article focusses on a combined approach involving a stereotactically guided and electrophysiologically controlled surgery. The instruments used (stereotactical system and electric stimulator) are available in almost every neurosurgical department in the Western and Eastern world and had been the first navigation systems in the human brain.

Brain Neoplasms↗

PubMed2000

Virtual endoscopy for planning endoscopic third ventriculostomy procedures.

Virtual endoscopy was used to plan 10 endoscopic third ventriculostomy procedures in 9 patients suffering from occlusive hydrocephalus due to idiopathic aqueductal stenosis and tumors. The patients were 4 children (4-14 years, mean age: 9 years) and 5 adults (21-38 years, mean age: 29 years). The aim of the study was to preoperatively evaluate the individual intraventricular and vascular endoscopic anatomy at the floor of the third ventricle based on virtual endoscopic images. The virtual views were correlated with the real endoscopic images, intraoperatively obtained by a standard ventriculoscope (Wolf, Knittlingen, Germany) during endoscopic third ventriculostomy procedures. Contrast-medium-enhanced MR images (3D-MPRAGE; Siemens, Germany) were semiautomatically segmented with a surface-rendering technique ('Navigator' software; General Electric Medical, Buc, France) to produce the virtual endoluminal views. The virtual endoscopic images were comparable with the real intraoperative endoscopic view in 8 of 9 patients. Virtual endoscopy can display the position of the basilar artery, the posterior cerebral arteries and the posterior communicating arteries in their relationship to the mammillary bodies and the clivus. Preoperative virtual endoscopy planning can intraoperatively assist the neurosurgeon to find a safe location for third ventriculostomy.

Adolescent↗

PubMed2000

Computer-assisted neurosurgery by using a noninvasive vacuum-affixed dental cast that acts as a reference base: another step toward a unified approach in the treatment of brain tumors.

OBJECT: The purpose of the study was to evaluate the use of the Vogele-Bale-Hohner (VBH) mouthpiece, which is attached to the patient's upper jaw by negative pressure, for patient-image registration and for tracking the patient's head during image-guided neurosurgery. METHODS: A dynamic reference frame (DRF) is reproducibly mounted on the mouthpiece. Reference points, optimally distributed and attached to the mouthpiece, are used for registration in the patient's absence on the day before surgery. In the operating room, the mouthpiece and DRF are precisely repositioned using a vacuum, and the patient's anatomical structures are automatically registered to corresponding ones on the image. Experimental studies and clinical experiences in 10 patients confirmed repeated (rigid body) localization accuracy in the range of 0 to 2 mm, throughout the entire surgery despite movements by the patient. CONCLUSIONS: Because of its noninvasive, rigid, reliable, and reproducible connection to the patient's head, the VBH vacuum-affixed mouthpiece grants the registration device an accuracy comparable to invasive fiducial markers.

Adult↗

PubMed1999

Virtual neuroendoscopy, a comparative magnetic resonance and anatomical study.

We evaluated the usefulness and reliability of intraventricular virtual neuroendoscopy based on a comparative anatomical study. Virtual intraventricular endoscopic images were calculated from 3D magnetic resonance images in five anatomic specimens. Contiguous 1.2 mm slices of the specimen heads were acquired at a 1.5 T MR scanner using a 3D-gradient echo sequence. The images were then transferred to an independent 3D-workstation (Sun Spark 20). After scanning the specimen heads, real endoscopy within the cerebral ventricles of these brains was performed with a standard rod lens system. Comparison between real and virtual endoscopic views of the intraventricular topography was based on the same anatomical reference and landmarks. Acquisition of MR data and virtual image post-processing have been possible in all specimens. The virtual endoscopic images of the ventricles were comparable to the intraventricular views obtained by a standard rod lens system. Virtual intraventricular neuroendoscopy can be employed for planning and simulating neuroendoscopic procedures. It enables the neurosurgeon to simulate the endoscopic procedure within the cerebral ventricles on the basis of the patient's individual anatomy prior to surgery.

Cerebral Ventricles↗

PubMed1998

Three-dimensional computer assisted magnetic resonance imaging for neurosurgical planning in parasagittal and parafalcine central region tumors.

Usually, conventional magnetic resonance spin echo images (MRI) are sufficient to establish the diagnosis of intracranial pathology. Planning and executing a neurosurgical procedure requires the ability of the neurosurgeon to transform these two-dimensional MRI into a three-dimensional (3-D) virtual image of the pathology and the surrounding neuronal anatomy. Such mentally performed transformations after sequential observation of the individual two-dimensional slices (i.e., MRI and angiography) may be virtual tasks that are very difficult or sometimes impossible to achieve. Using 3-D MRI data sets and a semiautomatic computer assisted segmentation technique, we tried to simulate intraoperative situs-based 3-D MRI reconstructions of parasagittal and parafalcine central region tumors. The MRI reconstructions were integrated into the neurosurgical planning procedure as an additional tool. They proved to be an important adjunct in determining the distinct anatomy of the intracranial pathology in its relation to the surrounding and overlying brain and vascular (especially venous) anatomy. With 10 patients with central region parasagittal and parafalcine tumors, we found that the 3-D MRI reconstructions revealed additional information compared to conventional cross-sectional images and had an influence on neurosurgical planning and strategy, improving neurosurgical performance and patient outcome.

Humans↗

PubMed1997

Hypocapnia reverses the fentanyl-induced increase in cerebral blood flow velocity in awake humans.

Investigations on the effects of opioids on cerebrovascular dynamics have repeatedly demonstrated mild to moderate increases in cerebral blood flow velocity in the middle cerebral artery (CBFVMCA), cerebral blood flow, and cerebrospinal fluid pressure in humans and animals. However, the influence of hypocapnia on these fentanyl effects has not been investigated. We compared mean CBFVMCA during normo- and hypocapnia before and after administration of fentanyl (2.5 micrograms/kg i.v.) in 20 awake humans. During normocapnia (end-tidal carbon dioxide [ETCO2] 40 mmHg) fentanyl significantly increased mean CBFVMCA (60 +/- 10 cm/s vs. 81 +/- 12 cm/s [mean +/- SD]; p < 0.01), whereas during hypocapnia (ETCO2 25 mmHg) mean CBFVMCA values were identical (40 +/- 7 cm/s vs. 40 +/- 7 cm/s) before and after fentanyl administration. These results confirm previous findings that administration of fentanyl increases CBFVMCA, but, more importantly, clearly indicate that hypocapnia reverses this potentially undesirable effect.

Adult↗

PubMed1996

Magnetic resonance volumetry of the cerebellum in epileptic patients after phenytoin overdosages.

The aim of this study was to evaluate the relationship between phenytoin medication and cerebellar atrophy in patients who had experienced clinical intoxication. Five females and 6 males, 21-59 years of age, were examined with a 1.5-T whole-body system using a circular polarized head coil. Conventional spin echo images were acquired in the sagittal and transverse orientation. In addition, we performed a high-resolution 3D gradient echo, T1-weighted sequences at a 1-mm slice thickness. The images were subsequently processed to obtain volumetric data for the cerebellum. Cerebellar volume for the patient group ranged between 67.66 and 131.08 ml (mean 108.9 ml). In addition 3D gradient echo data sets from 10 healthy male and 10 healthy female age-matched volunteers were used to compare cerebellar volumes. Using linear regression we found that no correlation exists between seizure duration, elevation of phenytoin serum levels and cerebellar volume. However, multiple regression for the daily dosage, duration of phenytoin treatment and cerebellar volume revealed a correlation of these parameters. We conclude that phenytoin overdosage does not necessarily result in cerebellar atrophy and it is unlikely that phenytoin medication was the only cause of cerebellar atrophy in the remaining patients. Quantitative morphometric studies of the cerebellum provide valuable insights into the pathogenesis of cerebellar disorders.

Adult↗

PubMed1994

Imaging of inner cerebral trauma.

The concept of "Inner cerebral trauma" (ICT) has been preliminary defined as a characteristic topographic pattern of deep brain lesions produced by physical forces occurring within the cranial cavity in closed head injury of the acceleration/deceleration type. The lesions, based on neuropathological examinations, are characteristically localized in the "centro-axial" regions of the brain. The extent of ICT is often underestimated by CT. Due to assess the value of MR imaging, 83 patients with ICT were examined on a 1.5 T unit in different stages after trauma. The pattern of lesions, as shown with MR imaging, correlated well with neuropathological studies, suggesting a multifocal pathogenesis of severe traumatic brain injury.

Adolescent↗