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Biomedical subjects

Steffen K Rosahl

Publications and source records attributed to Steffen K Rosahl.

11 recordsLinked to original sources
PubMed2006

Virtual reality augmentation in skull base surgery.

OBJECTIVE: Skull base anatomy is complex and subject to individual variation. Understanding the complexity of surgical anatomy is faster and easier with virtual models created from primary imaging data of the patient. This study was designed to investigate the usefulness of virtual reality in image guidance for skull base procedures. DESIGN: Primary volumetric image data from 110 patients was acquired using magnetic resonance, computed tomography (CT), and CT angiography. Pathologies included lesions in the anterior, middle, and posterior skull base. The data were transferred to an infrared-based image-guidance system for creation of a virtual operating field (VOF) with translucent surface modulation and optional "fly-through" video mode. During surgery, the target registration error for anatomical landmarks was assessed and the VOF was compared with the patient's anatomy in the operative field. RESULTS: Complex structures like the course of the sigmoid sinus, the carotid artery, and the outline of the paranasal sinuses were well visualized in the VOF and were recognized by the surgeon instantly. Perception was greatly facilitated as compared with routine mental reconstruction of triaxial images. Accurate assessment of the depth of field and very small objects was not possible in VOF images. CONCLUSION: Supported by sound anatomical knowledge, creation of a virtual operating field for a surgical approach in an individual patient offers a déjà vu experience that can enhance the capabilities of a surgical team in skull base approaches. In addition, application of this technique in image-guided procedures assists in targeting or avoiding hidden anatomical structures.

Journal Article↗
PubMed2006

Applicability of an electrosurgical device based on electromagnetics in neurosurgery.

Because of electrical and thermal spread to healthy nervous tissue, the application of electrosurgical tools in neurosurgery has specific limitations. This is true for both bipolar and monopolar devices. These limitations are not inherent to an instrument in which action is based on electromagnetic interaction with human tissue. We evaluated the indications and the clinical applicability of a new radiofrequency electrosurgical unit that works on this biophysical principle. The system was found to be a useful addition for the resection of morphologically tougher tissue with keyhole approaches in which the ultrasound aspirator cannot easily be applied.

Brain Injuries↗
PubMed2005

Life-threatening bleeding from a vertebral artery pseudoaneurysm after anterior cervical spine approach: endovascular repair by a triple stent-in-stent method. Case report.

The incidence of injury to the cervical vertebral artery during surgery for stenosis of the cervical neuroforamina is very low. We present a case in which bleeding during microforaminotomy at the level C6/7 occurred. The bleeding could be controlled intraoperatively. Two days later, a life-threatening cervical hematoma required urgent bedside evacuation. A false aneurysm of the left cervical vertebral artery was successfully occluded by a modified triple stent-in-stent technique, maintaining the flow in the vessel.

Aneurysm, False↗
PubMed2005

Reliability of a new adjustable shunt device without the need for readjustment following 3-Tesla MRI.

INTRODUCTION: 3-Tesla (T) magnetic resonance imaging (MRI) offers high resolution imaging with improved signal quality. It also allows for improved functional investigations, most prominently with respect to fiber tracts and their relation to pathological lesions. Up to now, patients with adjustable shunt systems were not eligible for high field power magnetic resonance imaging. We have evaluated the effects of this technique upon a newly developed adjustable shunt valve. METHOD: Ten adjustable shunt devices were examined during routine and functional 3-T high field MRI examinations. Pressure settings were checked after 17 examinations each for all valves. There were no changes in pressure setting at all possible levels in any of the tested devices. No problems with the adjusting mechanism were observed during 340 examinations. CONCLUSION: This new shunt device offers the diagnostic benefit of high field magnetic resonance imaging in shunt-dependent patients who need an adjustable valve. The valve is not affected by higher magnetic field power and does not require readjustment of the pressure settings after MRI examination.

Brain Diseases↗
PubMed2005

Electrical stimulation of the cochlear nerve in rats: analysis of c-Fos expression in auditory brainstem nuclei.

We investigated functional activation of central auditory brainstem nuclei in response to direct electrical stimulation of the cochlear nerve using c-Fos immunoreactivity as a marker for functional mapping. The cochlear nerve was stimulated in the cerebellopontine angle of Lewis rats applying biphasic electrical pulses (120-250 muA, 5 Hz) for 30 min. In a control group, bilateral cochlectomy was performed in order to assess the basal expression of c-Fos in the auditory brainstem nuclei. The completeness of cochlear ablations and the response of auditory brainstem nuclei to electrical stimulation were electrophysiologically verified. C-Fos immunohistochemistry was performed using the free floating method. In anaesthetized animals with unilateral electrical stimulation of the cochlear nerve, increased expression of c-Fos was detected in the ipsilateral ventral cochlear nucleus (VCN), in the dorsal cochlear nucleus bilaterally (DCN), in the ipsilateral lateral superior olive (LSO) and in the contralateral inferior colliculus (IC). A bilateral slight increase of c-Fos expression in all subdivisions of the lateral lemniscus (LL) did not reach statistical significance. Contralateral inhibition of the nuclei of the trapezoid body (TB) was observed. Our data show that unilateral electrical stimulation of the cochlear nerve leads to increased expression of c-Fos in most auditory brainstem nuclei, similar to monaural auditory stimulation. They also confirm previous studies suggesting inhibitory connections between the cochlear nuclei. C-Fos immunoreactivity mapping is an efficient tool to detect functional changes following direct electrical stimulation of the cochlear nerve on the cellular level. This could be particularly helpful in studies of differential activation of the central auditory system by experimental cochlear and brainstem implants.

Animals↗
PubMed2005

High-resolution constructive interference in steady-state imaging in tethered cord syndrome: technical note.

BACKGROUND: Differentiation between nerve roots and the tethered filum terminale in magnetic resonance images remains challenging. It is, however, crucial to select patients for surgical intervention. METHOD: In 1 patient with progressive and 2 patients with stable clinical signs of tethered cord syndrome (TCS), images reconstructed from a 3D constructive interference in steady-state (CISS) sequence were compared with those obtained from a regular T2-weighted fast spin echo sequence. RESULTS: Nerve roots of the cauda equina were suppressed, whereas visualization of the filum terminale was much improved in high-resolution CISS sequences. In addition, the level of adhesion of the filum could be localized in relation to elements of the spinal cord. The imaging results were confirmed during surgery and the patient improved considerably after the intervention. The advantages of CISS were also apparent in 2 other patients who are still being observed. CONCLUSION: Constructive interference in steady-state imaging should be considered in the presurgical routine for patients with TCS.

Adult↗
PubMed2003

C-Fos immunoreactivity mapping of the auditory system after electrical stimulation of the cochlear nerve in rats.

The aim of this study was to establish the use of c-Fos immunoreactivity as a marker for functional mapping in the auditory system in response to direct electrical stimulation of the cochlear nerve in the cerebellopontine angle. In rats the cochlear nerve was electrically stimulated with a biphasic current (120-250 microA, 5 Hz) for 30 min using a bipolar concentric Tungsten electrode. Bilateral cochlectomy was performed in a control group in order to investigate basal expression of c-Fos in the auditory brainstem nuclei. The response of auditory brainstem nuclei to electrical stimulation and the completeness of cochlear ablations were electrophysiologically verified. After the experiments, the animals were prepared for cryotomy and c-Fos immunohistochemistry. The results were morphologically analyzed and statistically compared among groups. In anesthetized animals with unilateral electrical stimulation of the cochlear nerve increased expression of c-Fos was detected in the ipsilateral ventral (VCN) and bilateral dorsal cochlear nucleus (DCN), whereas the VCN of the contralateral side revealed only few immunoreactive cells. In animals with bilateral cochlear ablation the number of c-Fos reactive cell nuclei representing basal expression was generally low in the VCN and DCN of both sides. Our data show that electrical stimulation of the cochlear nerve leads to increased expression of c-Fos in the cochlear nucleus. It also confirms bilateral connections between the cochlear nuclei. These experimental results suggest that c-Fos immunoreactivity mapping provides a powerful tool for functional investigations on the cellular level after direct electrical stimulation of the cochlear nerve. Future functional studies analyzing the effect of electrical stimulation of the central auditory system as performed by auditory brainstem implants could be investigated in detail by mapping c-Fos expression on cellular level.

Animals↗
PubMed2003

"Nihil nocere" and beyond: the issue of leadership in healthcare.

The quality of leadership is usually assessed in terms of business performance, which is reflected in expenditure and revenue figures. Although cost efficiency becomes an ever more important factor in healthcare, financial revenue is not the only defining factor for quality of leadership in a business where the consequence of failure may be deadly in the true sense of the word. Moreover, since "health" and "well-being" are both complex issues involving a variety of psychological variables, customer satisfaction in this field is not always strictly related to the quality of the delivered care. This difficulty in the definition of an accomplished leader in healthcare may have added to the negligence in developing leadership in this field.

Administrative Personnel↗
PubMed2002

Skin markers for surgical planning for intradural lesions of the thoracic spine. Technical note.

BACKGROUND: Preparation for surgery for thoracic intraspinal lesions commonly involves rather difficult X-ray procedures in the operating room. The object of this report is to inform neurosurgeons about a modified technique for preoperative surface localization of intraspinal thoracic pathology. METHODS: Adhesive, disposable radiographic skin markers placed at the presumed level of an intraspinal lesion are visualized along with the lesion on sagittal magnetic resonance scans of the thoracic spine. RESULTS: The lesion and the skin markers were clearly identified within the same field of view. The lesion itself rather than the vertebral body becomes the reference point for localization. CONCLUSION: Preoperative imaging with adhesive skin markers facilitates positioning and draping for surgery for thoracic intraspinal lesions. It may even replace intra-operative X-ray procedures in selected cases.

Adhesives↗
PubMed2002

Renal metastasis.

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Brain Neoplasms↗