Jan Kaminsky

Image-guided sphenoid wing meningioma resection and simultaneous computer-assisted cranio-orbital reconstruction: technical case report.

OBJECTIVE Resection of large intraosseous sphenoid wing meningiomas is traditionally associated with significant morbidity. Rapid prototyping techniques have become widely used for treatment planning. Yet, the transfer of a treatment plan into the intraoperative situs strongly depends on the experience of the individual surgeon. CLINICAL PRESENTATION Extensive resection with orbital decompression was planned and performed on the basis of rapid prototyping and surgical navigation techniques in a 44-year-old woman presenting with a large sphenoid wing meningioma on the right infiltrating the orbit. RESULTS Tumor resection was simulated on a stereolithography model of the patients head. The stereolithography model was scanned using computed tomography (CT) and the defect geometry was used to create a custom-made titanium implant. The implant consisted of a solid titanium core and a spot-welded titanium mesh surrounding the core, allowing for minor intraoperative adjustments of the implant size by reducing the mesh size. The stereolithography model with the incorporated implant was CT scanned again and the CT data were fused with the patients original CT data. The implant borders indicating the resection borders were marked within the patients CT data set. This treatment plan was transferred to an optical navigation system. Intraoperatively, tumor resection was performed using surgical navigation. CONCLUSION In the presented case report, the combination of computer-assisted planning using rapid prototyping techniques and image-guided surgery allowed for an extensive tumor resection precisely according to a preoperative treatment plan in a patient presenting with a large intraosseous sphenoid wing meningioma. A larger clinical series with a long-term follow-up period will be needed to determine the reproducibility.

Navigation-guided opening of the internal auditory canal via the retrosigmoid route for acoustic neuroma surgery: cadaveric, radiological, and preliminary clinical study.

OBJECTIVE We investigated the usefulness of a microscope-based navigational system (Multi Koordinaten Manipulator; Zeiss, Oberkochen, Germany) for removal of the posterior wall of the internal auditory canal (IAC) via the retrosigmoid route. METHODS A cadaveric study was performed to assess the navigational localization error for the retrosigmoid approach to the IAC. Computed tomographic findings for 47 acoustic neuroma cases were divided into three groups, on the basis of the relationship between the labyrinth and the sigmoid-fundus line (medial, on the line, or lateral). Furthermore, the shortest distances between the most medial labyrinthine extension and the resection line were measured. In 20 acoustic neuroma operations, the different features and the practicality of the microscope-based navigational system for opening of the IAC were evaluated. RESULTS The mean anatomic localization errors were 0.67 +/- 0.2 mm (95th percentile, 1.32 mm) for navigation to the IAC and 0.71 +/- 0.37 mm (95th percentile, 1.68 mm) for navigation to the posterior semicircular canal. The average distances between the most medial labyrinthine extension and the resection line were 3.65, 3.36, and 2.0 mm for the lateral, on-the-line, and medial groups, respectively. Direct contouring of structures at risk does not take into account the localization error, nor does it provide reliable navigational information. A novel indirect contouring concept that takes into account the localization error (the safety corridor method) was therefore introduced. CONCLUSION The value of navigational assistance for opening of the IAC is promising but still limited. Further development is required before the clinical effects of this navigational approach can be evaluated.

The impact of petrosal vein preservation on postoperative auditory function in surgery of petrous apex meningiomas.

OBJECTIVE: The importance of preserving the superior petrosal vein has received increasing attention in the surgical treatment of pathologies involving the petrous apex. Recent reports have associated postoperative auditory nerve dysfunction with petrosal vein sacrifice. However, there is no systematic clinical study available thus far focusing on the postoperative auditory function after petrosal vein obliteration. METHODS: In 55 patients with meningiomas involving the petrous apex, pre- and intraoperative findings including petrosal vein sectioning were analyzed retrospectively concerning their impact on postoperative auditory function. RESULTS: The petrosal vein was preserved in 26 (47%) cases. In 27 (49%) cases, this vein was not preserved. Hearing loss occurred in 11% of all cases. In the preserved-vein group, postoperative hearing loss occurred in 3 of 26 (11%) cases and in the sacrificed-vein group in 3 of 27 (11%) cases. CONCLUSION: Sacrifice of the petrosal vein during surgery of petrous apex meningiomas seems not to have an impact on postoperative auditory function.

Technical considerations regarding accuracy of the MKM navigation system. An experimental study on impact factors.

The purpose of this study was to investigate experimentally, factors determining the navigation accuracy of the MKM navigation system by Zeiss. The MKM consists of an operating microscope mounted to a six-axis motor-driven robot arm and an alpha-workstation. The image-guided surgery device provides navigation information based on calculation of the cartesian coordinates of the robot arm, and coordinates of the focus point assessed by laser assisted measurement. Navigation information (current position, direction and distance to a previously selected target) is optically projected into the microscopic field. Following factors were examined in an experimental setting for their impact on accuracy of the MKM: optical system, mechanical precision of the robot arm, and registration procedure. The robot arm and the optical system of the microscope allow high precision measurements of any focus point (error < 2 mm if the following aspects are considered: the use of auto-focus function instead of manual focusing, positioning of the registration points as a square or a triangle focus point should be selected on a surface that is perpendicular to the optical axis.

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

Introduction3-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.

Nausea and Dizziness after Vestibular Schwannoma Surgery: A Multivariate Analysis of Preoperative Symptoms

OBJECTIVE:Nausea and dizziness are very discomforting for patients after vestibular schwannoma surgery and they impair recovery. METHODS:To identify preoperative symptoms and conditions that increase the risk of development of nausea after vestibular schwannoma surgery, a multivariate analysis was performed. One hundred fifteen patients with vestibular schwannoma had a microsurgical tumor removal in a standardized procedure in 2001 and 2002. Eighteen patients were excluded from the study because of previous surgery (recurrent tumors, 7 patients) or bilateral tumor occurrence (neurofibromatosis, 11 patients). Analysis was performed regarding postoperative amount of antiemetic medication, vomiting, and subjective feeling of the patient. Tumor grading, body mass index, sex, previous complaints, examination at admission, and side of the tumor were taken in consideration. RESULTS:Women had significant longer postoperative complaints (mean, 3.0 d; standard error, 0.47) and needed longer antiemetic therapy (mean, 3.3 d; standard error, 0.49) than men (mean, 1.72 d; standard error, 0.21). Patients developing no significant postoperative complaints were all in the higher tumor grading group, Grades 3a, 4a, and 4b. There was a significant difference in the duration of antiemetic therapy between tumors graded 1 and tumors graded 3 or 4. Patients with a positive stepping test preoperatively had a tendency to demand less antiemetic medication. Women with small tumors are most likely to develop significant complaints after vestibular schwannoma surgery. CONCLUSION:It is possible to identify patients with a higher risk of postoperative nausea and dizziness after vestibular schwannoma surgery. This allows one to inform these patients preoperatively and to initiate an early postoperative drug therapy to ease their symptoms.

Cranial nerve deficits caused by uncommon skull base lesions of the cavernous sinus

Bei der klinisch-neurologischen Untersuchung zeigt sich eine partielle Augenmuskelparese des N. trochlearis und des N. abducens rechts mit Doppelbildersehen beim Blick nach unten und nach rechts sowie eine fingerperimetrisch erfassbare Gesichtsfeldeinschränkung im rechten oberen Quadranten. Unter der klinischen Annahme einer Läsion im Bereich der vorderen Sehbahn auf Höhe des Sinus cavernosus wird eine kranielle Bildgebung veranlasst. Diagnostik

Auditory rehabilitation after long-term deafness.

OBJECTIVEThe duration of preexisting profound deafness in patients with bilateral retrocochlear lesions is known to correlate negatively to the extent of auditory restoration after auditory brainstem implantation. There is, therefore, a lack of information regarding the potential of the central auditory system to mediate hearing perception after long-term deafness. METHODSThe authors evaluated auditory perception in a case of auditory brainstem implantation after 35 years of deafness. RESULTSElectrically evoked auditory brainstem potentials could be elicited by both stimulus polarities and were consistent with auditory brainstem origin. Discrimination between temporal and spectral patterns in speech could be achieved. This permitted us to distinguish various voice qualities, especially of familiar speakers in quiet surroundings. CONCLUSIONThe potential of the deafferentiated central auditory system to mediate auditory brainstem implant-induced hearing perception even after very long-term deafness has been demonstrated. Those patients with complete dysfunction of Cranial Nerve VIII for a long period may be considered as candidates for auditory brainstem implantation in the future.

Surgical removal of a symptomatic paracondylar process.

The paracondylar process is a rare congenital abnormality of the craniocervical junction that has been identified as a causative agent for severe headache, neck pain, and restricted head movement. Although conservative treatment is usually sufficient, the authors report the case of a symptomatic paracondylar process in a young patient who required surgical intervention.

3D segmentation and finite element modelling of spine segments

Abstract For imaging purposes of the spine, segmented image data provide the basis of modern medical applications. Among them, finite element (FE) modelling for biomechanical analysis represents a promising tool in decision making and optimizing individual therapy in the future. Both the anatomical complex structure of the spine and the degenerative bony deformations apparent in the clinical situation complicate the application of fully automated segmentation and finite element modelling. We developed a software system that was specifically adapted to the spine anatomy, and enables a fast and accurate segmentation. That is provided by special adapted segmentation tools, taking the “axis”-skeletal structure of the spine into account (rotation transformation and warped dissection plane). Specifically bony parts with extensive degeneration can be presented with sufficient accuracy. The segmented data were further processed with a fully automatic FE model generation software. Compared to other automated model generators, the described system allows a more reliable representation of anatomical boarders without smoothing inaccuracies. The software was successfully applied to 30 cervical, thoracic and lumbar spines. Based on the present software environment, setup of multi-modal (CT- and MRI data-based) geometric models is a key of future investigation.