[Extensive digital necrosis during dermatomyositis associated with MDA-5 antibodies]. / Nécroses digitales étendues au cours d'une dermatomyosite avec anticorps anti-MDA-5.

BACKGROUND: Dermatomyositis (DM) is an inflammatory disease associated with auto-antibodies in 50 to 70% of cases. A new antibody, anti MDA-5, has been described in association with a specific type of DM involving severe interstitial lung disease and minimal muscle disease. We report the first case of DM with MDA-5 antibodies and with interstitial lung disease and rapidly extensive digital necrosis. PATIENTS AND METHODS: A 28-year-old male was hospitalized for asthenia, myalgia and subacute dyspnea. Examination demonstrated skin lesions with edema on every digit associated with purpuric and cyanotic lesions, as well as erythematous papules on the helix and the elbows, and Gottron's papules. Systemic corticosteroid therapy was initiated. The immunoprecipitation results indicated the presence of anti-MDA-5 antibodies. Despite corticosteroid therapy, the patient's respiratory status gradually deteriorated towards pulmonary fibrosis and rapidly extensive necrosis appeared on all fingers and toes. Theses effects were resistant to cyclophosphamide and immunoglobulin but were stabilized by cyclosporine. DISCUSSION: Anti-MDA-5 antibodies are specific to DM and constitute a risk factor for severe interstitial lung disease (70% of cases) with a higher risk of mortality (40%). The cutaneous presentation of this DM is specific with palmar papules and mucocutaneous ulceration. Rapidly extensive digital necrosis has not been previously reported. No treatment has demonstrated superiority. CONCLUSION: We report the first case of DM with anti-MDA-5 antibodies involving interstitial lung disease and massive digital necrosis. Because of the pulmonary risk, in the presence of clinical lesions containing anti-MDA-5 DM, screening for these antibodies should be carried out.

Piezosurgical lateral suboccipital craniectomy and opening of the internal auditory canal in the rat.

AIM: Rotating burs (RB), routinely used in skull base and cerebellopontine angle (CPA) surgery for craniotomy and opening of the internal auditory canal (IAC) carry some risks for neurovascular tissue due to their rotating power. This paper describes the use of piezosurgery (PS), which selectively cuts bone with preservation of soft tissue, in lateral suboccipital craniectomy and opening of the IAC in the rat. METHODS: A lateral suboccipital craniectomy and opening of the bony IAC were performed with the Mectron® piezosurgical device under microsurgical conditions in the anesthezised rat. The piezosurgical device was evaluated with respect to practicability, safety, preciseness of craniectomy and IAC opening, and preservation of adjacent neurovascular tissue. The operation procedure is described in detail. RESULTS: The present work shows that PS allows easy, safe and precise bone cutting with no injury to neurovascular tissue, such as dura, transverse or sigmoid sinus, brain, and cranial nerves. No complications were noted during the procedure. Due to the absence of rotating power near neurovascular structures the drilling process was easy and comfortable for the surgeon. CONCLUSION: PS proved to be a safe, precise and easy to handle tool to perform suboccipital craniectomy and opening of IAC in the rat. Since PS makes the drilling process safer and more comfortable compared to a rotating bur it may be used instead of rotating burs in all scientific applications in animal models where a safe removal of bone near delicate nervous or soft tissue structures is essential.

[Nuchal swelling]. / Nuchale Schwellung.

In the unusual case of a 68-year-old woman with one-sided painless lateral neck swelling, the ENT examination showed a firm nuchal mass (4 × 4 cm) on the right side with no other pathological findings. Angio-MRI confirmed a solid, sharply demarcated tumor with arterial hyperperfusion. Core needle aspiration biopsy was performed, revealing well-circumscribed tufts showing the typical "cannonball" aspect. After preoperative embolisation we performed extirpation of the mass. Histological examination showed an acquired tufted angioma. Clinical as well as radiological follow-up examination detected neither local relapse nor metastases.

The clinico-surgico-pathological spectrum of myxopapillary ependymomas--report of four unusal cases and review of the literature.

According to the WHO grading system, myxopapillary ependymomas are assigned to WHO Grade I. However, the clinico-pathological spectrum might be very heterogenous. Herein, we report 4 cases exhibiting lumbar tumor masses, 1 causing muscular atrophy over a 30-year period, 3 displaying clinical history of persisting lumbar pain for only several weeks. All tumors were crooked with dura and spinal roots resulting in incomplete resection in three cases. On histological examination, two tumors were almost acellular and showed polycyclic hyaline and fibrotic extracellular matrix leading to differential diagnoses of chordoma, meningioma, fibrolipoma and ependymoma. Finally, together with the immunohistochemical investigations, electron microscopy led to the diagnosis of myxopapillary ependymoma, WHO Grade I, with massive degenerative changes. The other 2 cases presented with the typical neuropathology of myxopapillary ependymomas but showed local recurrence within 1 and 13 years throughout the whole neuraxis, and in 1 case additional metastases of the 3rd ventricle. Although the morphological feature of these myxopapillary ependymomas was benign, the presented cases showed that the biological behavior of myxopapillary tumors might differ greatly and that these tumors present a serious operative and diagnostic challenge. Myxopapillary ependymomas occur most often in the lumbosacral region. Due to the anatomic complexity of the cauda equina, a complete resection can be technically challenging in this region. However, a gross total resection at the primary surgery is the most predictive factor for the outcome.

Minimally invasive removal of an extradural intraradicular lumbar schwannoma.

OBJECTIVE: Surgical exposure of peripheral lumbar schwannomas often requires extensive muscle mobilization which results in significant postoperative pain. We describe an alternative minimally invasive surgical technique for the treatment of such lesions. METHODS: We report the case of a patient with an extradural intraradicular schwannoma of the L4 root that was treated with a minimally invasive transmuscular approach by using tubular retractors. RESULTS: Muscle trauma and intraoperative blood loss were negligible. The postoperative course was uneventfull. There was no additional morbidity associated with the approach. The patient was discharged 72 h after the procedure. CONCLUSIONS: In selected cases extradural intraradicular lumbar schwannomas can be treated adequately with a minimally invasive transmuscular approach.

Endoscope-assisted retrosigmoid intradural suprameatal approach to the middle fossa: anatomical and surgical considerations.

INTRODUCTION: Lesions involving the posterior and middle fossa may be reached by several surgical approaches depending mostly on tumors' location and characteristics. The retrosigmoid intradural suprameatal approach has been used to remove tumors of the posterior fossa extending into Meckel's cave and the middle fossa. With large tumors, this approach may allow exposure of the oculomotor and optic nerves, the supraclinoid internal carotid and communicating posterior arteries. METHODS: Three formaldehyde-fixed specimens have been prepared on both sides using the conventional retrosigmoidal-suprameatal approach. The entire endoscopic preparations have been documented via a digital recording system, using a 5mm endoscope with a 25 degrees perspective. The authors describe the anatomical corridor and technique of the endoscope-assisted retrosigmoid intradural suprameatal approach to lesions that are located predominantly within the posterior fossa and supratentorial extension into Meckel's cave, sellar and parasellar region. CONCLUSIONS: The endoscope-assisted suprameatal approach provides exposure of the antero-medial middle fossa even in cases of skull base lesions that have not caused significant displacement of neurovascular structures.

Rosai-Dorfman disease involving the cranial base, paranasal sinuses and spinal cord.

Rosai-Dorfman disease is a lymphoproliferative disease that rarely involves the central nervous system. A 32-year-old patient with an extensive process involving the petroclival region, cavernous sinuses, suprasellar region, anterior cranial fossa, paranasal sinuses, nasal cavity and spinal cord is reported. Sinus histiocytosis with massive lymphadenopathy lesions may be dural-based and located in the skull base. As these lesions may clinically and radiologically mimic meningiomas as well as other disorders, Rosai-Dorfman disease should be included in the differential diagnosis of extensive lesions involving the intracranial and spinal compartments along with meningiomatosis and inflammatory diseases. The individual management of Rosai-Dorfman disease may be challenging due to diffuse involvement of neurovascular structures at the skull base.

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.

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.

Sensitivity of femoral strain pattern analyses to resultant and muscle forces at the hip joint.

An automated geometrical preprocessor was developed with the aim of creating three-dimensional finite element models (FEM) of the human femur. On the basis of postprocessed computed tomography data, this preprocessor makes possible rapid, flexible and regular meshing with 'brick' elements. Three different material properties were modelled at the present stage of development. Sensitivity analyses demonstrated that the strain energy density (SED) patterns of the different femoral parts were most sensitive to the implementation of an iliotibial tract force. The variation of the resultant hip force and abductor force direction within the sagittal plane demonstrated a SED minimum at an anterior inclination of 13 degrees; the variation of the resultant force direction within the frontal plane demonstrated a minimum SED at a medial inclination of 21 degrees relative to the mechanical axis of the lower limb. The orientation of the connecting line between the surface-SED-peaks in the horizontal view was found to be most sensitive to the variation of the resultant force within the sagittal plane.

Comparison of geometry-based and CT voxel-based finite element modelling and experimental validation.

The objectives of the paper presented here is the comparison of a geometry-based and voxel-based finite element (FE) method preprocessor of the human femur. The models were experimentally validated by strain gauge measurements (principal stress). The correlation coefficients (r) between the three methods (geometry-based FEM, voxel-based FEM, strain gauge measurements) were found to be in the range 0.91-0.94 (r2: 0.84-0.88). The relationships between the samples are highly significant (P = 0.001), where the strain gauge results are the independent variables. These results suggest that the validity with respect to the principal stress of a voxel-based modelling is similar to the validity of geometry-based modelling. In summary, therefore, we conclude that voxel-based meshing allows a straightforward interfacing with computerized tomography (CT) scans and might contribute to a clinically applicable FEM technology.

Universal interface for exchange of medical images via magneto-optical discs.

Digital images are the ever-growing basis of modern medical imaging and treatment. Despite the advent of the DICOM 3.0 standard for medical image communication it still requires cumbersome efforts to export images from imaging modalities to other computer systems. This is true especially for smaller institutions, which often have limited resources for standardized image transfer. To gain access even to these data we developed an exchange interface on the basis of magneto-optical discs (MO-discs), as they are usually available in most of the imaging modalities in use today. Unfortunately images on MO-discs are usually stored in formats specific for each manufacturer. Therefore special routines to access the data on MO-discs had to be developed for each company or even each scanner. Over 10,000 CT and MRI images including their header information from different General Electric and Siemens scanners were extracted successfully from MO-discs. The interface proved to be reliable and easy to handle by technicians. Support of additional manufacturers and of the DICOM 3.0 standard are work in progress.

[Development of a universal interface for the exchange of medical image data using magneto-optical media]. / Entwicklung einer universellen Schnittstellenumgebung zur Ubertragung medizinischer Bilddaten mit magnetooptischen Medien.

Digital images generated by medical imaging form the basis for radiological diagnosis and surgical planning. Despite the advent of the DICOM 3.0 standard for medical image communication, widespread application of the existing information is often limited by incompatibility of the data formatting used by different equipment generations, and the manufacturer-specific standards employed. An exchange interface based on magneto optical discs has been developed to retrieve and present medical image data regardless of the technological hardware and the specific formats used. Specially adapted routines to retrieve the data first had to be developed. A modular program structure was used to allow flexibility in the implementation of further routines and other exchange media. Over 20,000 CT and MRI images including header information obtained from different General Electric and Siemens scanners were extracted successfully from MO discs. The image data were used for follow up and surgical planning and were transferred to a PAC-server. The interface proved reliable and easy to use. Support for further proprietary formats is currently being developed. The present exchange interface permits reliable retrieval of digital images for diagnostic and surgical planning purposes, regardless of the hardware generation and manufacturer-specific formats.

[Multisegmental image fusion of the spine]. / Mehrsegmentale Bildfusion an der Wirbelsäule.

Fusion of medical images is a technique that permits the correlation of homologous anatomical structures in different imaging modalities on the basis of a spatial transformation of the data sets. CT and MRI of the spine provide complementary information of possible relevance for diagnostic and therapeutic decisions. Methods enabling a multisegmental CT-MRI fusion of the spine were developed. These solve the problem of altered spatial relationships of the individual anatomical structures due to differing patient positioning in successive data acquisitions. Routine clinical CT and MRI data of a thoracic section of the spine were obtained and transferred to a PC-workstation. Following segmentation of the CT-data, landmarks for each individual vertebra were defined in the CT and MRI data. For each individual vertebra the algorithm we developed then carried out a rigid registration of the CT information to the MR data. The fused data sets were presented as colour-coded images or on the basis of dynamic variation of transparency. To assess registration precision, fiducial registration errors (FRE) and target registration errors (TRE) were calculated. The algorithm permitted multi-segmental image fusion of the spine. The average time required for defining the landmarks was 22 seconds per landmark for CT, and 34 seconds per landmark for MR. The average FRE was 1.53 mm. The TRE for the vertebrae was less than 2 mm. The colour-coded images were particularly suitable for assessing the contours of the anatomical structures, whereas dynamic variation of the transparency of overlapping CT images enabled a better overall assessment of the spatial relationship of the anatomical structures. The algorithm permits precise multi-segmental fusion of CT and MR of the spine, which was not possible using current fusion-algorithms due to variations in the spatial orientation of the anatomical structures caused by different positioning of the axial skeleton in successive examinations.

[Automatic generation of 3-D finite element codes of the human femur]. / Automatisierte Generierung von 3-D Finite Elemente Codes des menschlichen Femurs.

The extremely irregular geometry of bones makes it very difficult to develop and preprocess three-dimensional finite element models (FEM). In the field of biomechanics, the finite element simulation method is a research tool of increasing importance for the prediction of stresses and the stress-compatibility testing of endoprostheses. With this in mind, a FEM preprocessor was developed with the aim of creating three dimensional models of human femurs. On the basis of postprocessed computed tomography data, this preprocessor makes possible rapid, flexible and regular cross-linking. "Brick" elements are used, which are of advantage in terms of computing time, accuracy and computer storage requirements. The software simplifies the generation of models and facilitates the investigation of individual variations, thus providing the basis for utilizing the method in the clinical setting.

[Three-dimensional-segmentation of the spine with specially adapted tools]. / 3-D-Segmentierung der Wirbelsäule mit speziell angepassten Werkzeugen.

Segmented 3-D data of the spine form the basis for various modern clinical applications. Among these, multisegmental image fusion, image registration and finite element modeling for biomechanical analysis are promising innovative tools capable of facilitating treatment decisions and optimization of individual therapy in the future. However, the complex anatomy of the spine and the often extensive degenerative deformation presenting in clinical practice, generally limit the application of fully automated segmentation. A newly developed software system is presented that meets the complex requirements for image segmentation of the spine through the use of specially adapted interactive tools that take account of its axial skeletal structure. Furthermore, a standardized protocol is introduced that combines the newly developed interactive tools (rotation transformation, warped dissection plane) and standard segmentation tools to permit rapid and accurate segmentation. To date, the software environment presented herein has been applied with success to the segmentation of cervical, thoracic and lumbar spine.

[Therapy of posterior orbital tumors]. / Therapie posterior gelegener Orbitatumoren.

Tumors of the posterior orbit require different therapeutic modalities, depending on the histological entity. In the orbit all structures are in close relationship and the endocranium is in the direct proximity. This requires profound knowledge of topographic anatomy and high therapeutic precision. The surgical approach to the posterior orbit via a ventral intraorbital approach is strongly restricted due to the ocular bulb which consumes most space in the anterior orbit. Therefore if the bulb and vision are to be retained extraorbital surgical corridors are predominantly preferred. These are classified into extracranial and intracranial approaches. In detail, the former are medial transethmoidal orbitotomy, caudal transmaxillar orbitotomy and lateral orbitotomy. Frontolateral and frontotemporal orbitotomy as well as frontal, bifrontal and subfrontal orbitotomy are intracranial approaches. Apart from surgical methods there are several forms of radiotherapy which can be applied to orbital tumors under certain indications. Radiotherapy may be performed with external fractionated photon radiation or as stereotactic radiation, with heavy ions or protons or as brachytherapy. In this article various therapeutic interventions to the posterior orbit and the indications and potential side-effects are described.