Martin Leinung
Research interests
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InterestsOtology, Otorhinolaryngology, Robotic Assistance, Navigated Surgery, cochlear implant
Publications
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Determination of the curling behavior of a preformed cochlear implant electrode array.
International journal of computer assisted radiology and surgery. 05/2011; 6(3):421-33.
Accurate insertion of a cochlear implant electrode array into the cochlea's helical shape is a crucial step for residual hearing preservation. In image-guided surgery, especially using an automated insertion tool, the overall accuracy of the operative procedure can be improved by adapting the el... [more] Accurate insertion of a cochlear implant electrode array into the cochlea's helical shape is a crucial step for residual hearing preservation. In image-guided surgery, especially using an automated insertion tool, the overall accuracy of the operative procedure can be improved by adapting the electrode array's intracochlear movement to the individual cochlear shape. The curling characteristic of a commercially available state-of-the-art preformed electrode array (Cochlear Ltd. Contour Advance(TM) Electrode Array) was determined using an image-processing algorithm to detect its shape in series of images. An automatic image-processing procedure was developed using Matlab and the Image Processing Toolbox (MathWorks, Natick, Massachusetts, USA) to determine the complete curvature of the electrode array by identifying the 22 platinum contacts of the electrode. A logarithmic spiral was used for a comprehensive mathematical description of the shape of the electrode array. A fitting algorithm for nonlinear least-squares problems was used to provide a complete mathematical description of the electrode array. The system was tested for curling behavior as a function of stylet extraction using nine Contour Advance Research Electrodes (RE) and additionally for nine Contour Advance Practice Electrodes (PE). All arrays show a typical pattern of curling with adequate predictability after the first 2 or 3 millimeters of stylet extraction. Although non-negligible variations in the overall curling behavior were detected, the electrode arrays show a characteristic movement due to the stylet extraction and only vary minimally after this initial phase. These results indicate that the risk of intracochlear trauma can be reduced if the specific curling behavior of the electrode carrier is incorporated into the insertion algorithm. Furthermore, the determination of the curling behavior is an essential step in computer-aided cochlear implant electrode development. Experimental data are required for accurate evaluation of the simulation model.
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1.45Impact points
Accuracy of computer-aided geometric 3D reconstruction based on histological serial microgrinding preparation.
Computer methods in biomechanics and biomedical engineering. 11/2010; 14(7):581-94.
For our research on computer-optimised and automated cochlear implant surgery, we pursue a model-based approach to overcome the limitations of currently available clinical imaging modalities. A serial cross section preparation procedure has been developed and evaluated concerning accuracy to serve f... [more] For our research on computer-optimised and automated cochlear implant surgery, we pursue a model-based approach to overcome the limitations of currently available clinical imaging modalities. A serial cross section preparation procedure has been developed and evaluated concerning accuracy to serve for modelling of a digital anatomic atlas to make delicate soft tissue structures available for pre-operative planning. A special grinding tool was developed allowing the setting of a specific amount of abrasion as equidistant slice thickness was considered a crucial step. Additionally, each actual abrasion was accurately measured and used during three-dimensional reconstruction of the serial cross-sectional images obtained via digital photo documentation after each microgrinding step. A well-known reference object was prepared using this procedure and evaluated in terms of accuracy. Reconstruction of the whole sample was achieved with an error less than 0.4%, and the edge lengths in the direction of abrasion could be reconstructed with an average error of 0.6 ± 0.3 mm; both prove the realisation of equidistant abrasion. Using artificial registration fiducials and a custom-made algorithm for image alignment, parallelism and rectangularity could be preserved with average errors less than 0.4° ± 0.3°. We present a systematic, practicable and reliable method for the geometrically accurate reconstruction of anatomical structures, which is especially suitable for the middle and inner ear anatomy including soft tissue structures. For the first time, the quality of such a reconstruction process has been quantified and successfully proven for its usability.
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Automated insertion of preformed cochlear implant electrodes: evaluation of curling behaviour and insertion forces on an artificial cochlear model.
International journal of computer assisted radiology and surgery. 03/2010; 5(2):173-81.
As a substantial part of our concept of a minimally invasive cochlear implant (CI) surgery, we developed an automated insertion tool. Studies on an artificial scala tympani model were performed in order to evaluate force application when using the insertion tool. Contour electrodes were automaticall... [more] As a substantial part of our concept of a minimally invasive cochlear implant (CI) surgery, we developed an automated insertion tool. Studies on an artificial scala tympani model were performed in order to evaluate force application when using the insertion tool. Contour electrodes were automatically inserted into a transparent cochlea model in Advance Off-Stylet technique. Occurring forces were measured by the use of a load cell and correlated with observed intracochlear movement of the electrode carriers. Mean insertion forces were measured up to 20 mN comparable to previous studies on temporal bones. The most influencing factor is the implant's 2D curling behaviour in comparison to the 3D helical shape of the cochlea. The study confirms the functionality and reliability of the automated insertion tool for insertion of preformed CI. Improved insertion strategies considering patient-specific anatomy become possible.
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1.46Impact points
Time of cochlear implant surgery in academic settings.
Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery. 02/2010; 142(2):254-9.
Establish the time required to perform cochlear implantation (CI) in academic settings. Historical cohort study. German and American academic centers. A total of 2639 patients underwent CI (1997-2007). We excluded patients receiving an experimental device or technique and those with abnormal cochlea... [more] Establish the time required to perform cochlear implantation (CI) in academic settings. Historical cohort study. German and American academic centers. A total of 2639 patients underwent CI (1997-2007). We excluded patients receiving an experimental device or technique and those with abnormal cochlear anatomy or incomplete charts, leaving 2253 for analysis. Unilateral, bilateral, and revision CI with devices approved in the U.S. and Europe. Mean surgical time (ST) and total operating room time (TORT). Mixed model analysis was used; estimated marginal means were calculated in minutes after adjusting for random effect of individual surgeon. There were no differences between unilateral (ST = 171, TORT = 245) and revision CI (ST = 160, TORT = 232), but bilateral procedures were longer (ST = 295, TORT = 377, P < 0.001). In unilateral surgeries, Cochlear Limited (CL) devices were implanted faster (ST = 165, TORT = 225) than Advanced Bionics (ABC) (ST = 183, P = 0.001; TORT = 240, P = 0.023) or MedEl (ST = 193, P < 0.001; TORT = 253, P = 0.002) devices. There were no differences for unilateral CI between ABC and MedEl devices. For revision CI, ABC devices (ST = 141, TORT = 219) were implanted faster than CL devices (ST = 181, P = 0.001; TORT = 266, P < 0.001). There were no differences by age group or between Germany and the U.S. ST and TORT were shorter for 575 CIs performed in the final two years of the study (unilateral CI: ST = 145, TORT = 209; bilateral CI: ST = 259, TORT = 330; revision CI: ST = 138, TORT = 205). For unilateral CI, ST and TORT decreased yearly (linear regression, P < 0.001) and inversely correlated with surgeon experience (linear regression, P < 0.01). We report the time required to perform CI in academic settings-data that are vital for cost-benefit analyses and assessing new CI techniques.
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2.02Impact points
Contact endoscopy for the evaluation of the pharyngeal and laryngeal mucosa.
The Laryngoscope. 12/2009;
OBJECTIVES:: Contact endoscopy is a noninvasive tool that allows in vivo and in situ examination of superficial mucosa. Its use for early diagnosis of cancerous lesions of the oropharynx and larynx has not been evaluated. The aim of the study was to validate contact endoscopy for the examination of ... [more] OBJECTIVES:: Contact endoscopy is a noninvasive tool that allows in vivo and in situ examination of superficial mucosa. Its use for early diagnosis of cancerous lesions of the oropharynx and larynx has not been evaluated. The aim of the study was to validate contact endoscopy for the examination of pharyngeal and laryngeal mucosa. STUDY DESIGN:: Prospective clinical study. METHODS:: Superficial cells of the mucosa were stained with methylene blue and examined with contact endoscopes. The documented images were assessed by a cytopathologist and by an otolaryngologist independently for each patient. Biopsies for histopathological examination of the area were performed and correlated with contact endoscopic findings of both examiners. RESULTS:: Of the 42 examined specimen, 32 (76.2%) showed benign changes in the histological analysis. Squamous cell carcinoma was revealed in 10 specimen (23.8%). Using contact endoscopy, the cytopathologist accurately identified 90.6% of the benign findings (29 of 32); however, only seven of 10 (70%) carcinomas were correctly categorized. In comparison, the otolaryngologist made a correct diagnosis in 93.75% (30 of 32) of the benign and in 90% (nine of 10) of the malignant cases. Thus, a sensitivity of 90% and a specificity of 93.75% can be achieved by contact endoscopy. CONCLUSIONS:: Contact endoscopy offers valuable support for the evaluation of oropharyngeal, hypopharyngeal, and laryngeal mucosa. Contact endoscopy can be a useful contribution to rapid intraoperative evaluation of mucosal alterations for early diagnosis of tumors and might reduce diagnostic biopsy sampling. Even so, it does not replace biopsy sampling. Laryngoscope, 2010.
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A robot-guided minimally invasive approach for cochlear implant surgery: preliminary results of a temporal bone study.
International journal of computer assisted radiology and surgery. 09/2009; 4(5):475-86.
The aim of this study was to create an access canal to the inner ear, by drilling, and perform the cochleostomy for cochlear implant surgery using robot guidance. A robot, a surgical drill and an Image-Guided Surgery (IGS) system were combined in a closed-loop setup. Ten temporal bones were scanned ... [more] The aim of this study was to create an access canal to the inner ear, by drilling, and perform the cochleostomy for cochlear implant surgery using robot guidance. A robot, a surgical drill and an Image-Guided Surgery (IGS) system were combined in a closed-loop setup. Ten temporal bones were scanned at the planning stages of the procedure. The robot guided the drill along the preplanned trajectory and created the approach. Postoperative scans were obtained. The cochleostomy was performed completely in nine out of ten cases. This did not prove possible for one of the specimens, the target site selected being in too superficial a location in relation to the round window. No violation of the facial nerve took place, although the chorda tympani nerve was violated in one case and the stapes in two. It was obvious during preoperative planning that these structures would be violated, but this was accepted in order to maintain a safety margin from the facial nerve. No other unforeseen damage occurred. This preliminary study suggests that robot-guided drilling of a minimally invasive approach to the cochlea might be feasible, but further improvements are necessary before any clinical application becomes possible. Where the width of the facial recess is less than 2.5 mm, the chorda tympani nerve and the ossicles are at risk.
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0.65Impact points
Artifacts caused by cochlear implants with non-removable magnets in 3T MRI: phantom and cadaveric studies.
European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery. 08/2009;
The aim of this study was to evaluate artifacts produced by cochlear implants (CI) during 3.0 Tesla (T) magnetic resonance imaging of the brain using different sequences on phantom and cadaveric specimens. A phantom and three cadaveric specimens with CIs were imaged using a 3.0 T clinical scanner. A... [more] The aim of this study was to evaluate artifacts produced by cochlear implants (CI) during 3.0 Tesla (T) magnetic resonance imaging of the brain using different sequences on phantom and cadaveric specimens. A phantom and three cadaveric specimens with CIs were imaged using a 3.0 T clinical scanner. Artifacts were analyzed quantitatively and according to the sequence used. Different brain regions were evaluated for image distortion and limitation of diagnostic significance. In cadaver studies, all sequences generated signal-void areas around the implant. In T2-weighted sequences, additional periodic shadowing was discovered. Anatomical structures of the brain on the contralateral side of the CI were for the most part undistorted. At 3T, artifacts around CIs with non-removable magnets compromise image quality of the nearby brain regions and diagnosis of brain lesions is limited. In the contralateral hemisphere, diagnostic accuracy is only marginally limited.
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3.30Impact points
Temporal Bone Imaging: Comparison of Flat Panel Volume CT and Multisection CT.
AJNR. American journal of neuroradiology. 05/2009;
BACKGROUND AND PURPOSE: A recent development in radiology is the use of flat panel detectors in CT to obtain higher-resolution images. This technique is known as flat panel volume CT (fpVCT). We sought to compare the image quality and diagnostic value of 2 different flat panel detector-equipped scan... [more] BACKGROUND AND PURPOSE: A recent development in radiology is the use of flat panel detectors in CT to obtain higher-resolution images. This technique is known as flat panel volume CT (fpVCT). We sought to compare the image quality and diagnostic value of 2 different flat panel detector-equipped scanners: one is a prototype fpVCT scanner, and the other is a so-called flat panel digital volume tomography (fpDVT) scanner, which is routinely used in clinical setup with current state-of-the-art multisection CT (MSCT) scanners. MATERIALS AND METHODS: Five explanted temporal bones and 2 whole-head cadaveric specimens were scanned with fpVCT, fpDVT, and MSCT scanners. The image series were blindly evaluated by 3 trained observers who rated 38 anatomic structures with regard to their delineation/appearance. RESULTS: Although the image quality obtained with fpVCT and fpDVT was rated significantly better compared with MSCT on isolated temporal bones, the differences were not significant when whole cadaveric heads were scanned. CONCLUSIONS: Theoretic and practical advantages exist for flat panel detector-equipped scanners, including improved image quality. However, when imaging whole cadaveric heads, no significant difference could be demonstrated between them and standard-of-care MSCT.
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1.46Impact points
Demagnetization of cochlear implants and temperature changes in 3.0T MRI environment.
Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery. 01/2009; 139(6):833-9.
OBJECTIVE: To investigate the level of demagnetization of the magnets and temperature changes in cochlear implants (Cis) in a 3.0 tesla (3.0T) MRI. STUDY DESIGN: Experimental. SUBJECTS AND METHODS: Demagnetization and remagnetization measurements were done on magnets for different types of CIs. Temp... [more] OBJECTIVE: To investigate the level of demagnetization of the magnets and temperature changes in cochlear implants (Cis) in a 3.0 tesla (3.0T) MRI. STUDY DESIGN: Experimental. SUBJECTS AND METHODS: Demagnetization and remagnetization measurements were done on magnets for different types of CIs. Temperature of different body and electrode sides was measured in the MRI environment. RESULTS: Demagnetization of the magnets of the CI is dependent on the angle between the magnetic field of the CI magnet and the MRI. When this angle was greater than 80 degrees, relevant demagnetization occurred and sufficient remagnetization was not possible with the 3.0T MRI magnet. Maximum temperature rise was 0.5 degrees C. CONCLUSIONS: Patients carrying CIs with non-removable magnets should not enter a 3.0T MRI device in a routine clinical setup. Under special conditions (angle between the two magnets less than 80 degrees) imaging in a 3.0T MRI may be possible without harming the patient or the implant.
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1D-Messungen physiologischer Bewegungen am Hals mit optischer Kohärenztomographie.
Bildverarbeitung für die Medizin 2009: Algorithmen - Systeme - Anwendungen, Proceedings des Workshops vom 22. bis 25. März 2009 in Heidelberg; 01/2009
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1.33Impact points
Clinical feasibility test on a minimally invasive laser therapy system in microsurgery of nerves.
Minimally invasive therapy & allied technologies : MITAT : official journal of the Society for Minimally Invasive Therapy. 11/2008;
The clinical feasibility test described here evaluates the basis for a laser therapy system that enables tumour tissue to be separated from nerves in a minimally invasive manner. It was first investigated whether, using an Er:YAG laser, laser-induced nerve (specifically, facial nerve) responses in t... [more] The clinical feasibility test described here evaluates the basis for a laser therapy system that enables tumour tissue to be separated from nerves in a minimally invasive manner. It was first investigated whether, using an Er:YAG laser, laser-induced nerve (specifically, facial nerve) responses in the rabbit in vivo can be reliably detected with the hitherto standard monitoring techniques. Peripherally recordable neuromuscular signals (i.e. compound action potentials, CAPs) were used to monitor nerve function and to establish a feedback loop. The first occurrence of laser-evoked CAPs was taken as the criterion for deciding when to switch off the laser. When drawing up criteria governing the control and termination of the laser application, the priority was the maintenance of nerve function. Five needle-electrode arrays specially developed for this purpose, each with a miniature preamplifier, were then placed into the facial musculature instead of single-needle electrodes. The system was tested in vivo under realistic surgical conditions (i.e. facial-nerve surgery in the rabbit). This modified multi-channel electromyography (EMG) system enabled laser-evoked CAPs to be detected that have amplitudes 10 times smaller than those picked up by commercially available systems. This optimization, and the connection of the neuromuscular unit with the Er:YAG laser via the electrode array to create a feedback loop, were designed to make it possible to maintain online control of the laser ablation process in the vicinity of neuronal tissue, thus ensuring that tissue excision is both reliable and does not affect function. Our results open up new possibilities in minimally invasive surgery near neural structures.
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Conception and design of an automated insertion tool for cochlear implants
Engineering in Medicine and Biology Society, 2008. EMBS 2008. 30th Annual International Conference of the IEEE; 09/2008
Cochlear implants (CI) are electronic devices incorporating an electrode inserted into the human cochlea for direct electric stimulation of the auditory nerve. The implantation has become the standard treatment for patients with severe-to-profound sensorineural loss not aidable with conventional hea... [more] Cochlear implants (CI) are electronic devices incorporating an electrode inserted into the human cochlea for direct electric stimulation of the auditory nerve. The implantation has become the standard treatment for patients with severe-to-profound sensorineural loss not aidable with conventional hearing aids. The state of the art operative technique is a facial recess approach to the middle ear, following the opening of the scala tympani (cochleostomy) and insertion of the electrode array. The facial recess approach is applicable only by experienced surgeons and optimal CI results primarily depend on optimal electrode placement and minimal traumatic insertion. This also requires a certain amount of experience. Additionally several groups work on minimally-invasive approaches to the cochlea, resulting in the necessity to insert the implant via a keyhole access, which is not applicable with current techniques. This paper presents a mechatronic device for an automated insertion of the electrode array of a cochlear implant system. Being designed especially for minimally-invasive approaches, the tool is also applicable for regular facial recess approaches. Moreover the device allows reliable and repeatable insertion studies at synthetic models or cadaver specimen. The functionality of the tool is proofed with first experiments on a synthetic model.
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1.44Impact points
A true minimally invasive approach for cochlear implantation: high accuracy in cranial base navigation through flat-panel-based volume computed tomography.
Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. 03/2008; 29(2):120-3.
OBJECTIVE: High-precision intraoperative navigation using high-resolution flat-panel volume computed tomography makes feasible the possibility of minimally invasive cochlear implant surgery, including cochleostomy. Conventional cochlear implant surgery is typically performed via mastoidectomy with f... [more] OBJECTIVE: High-precision intraoperative navigation using high-resolution flat-panel volume computed tomography makes feasible the possibility of minimally invasive cochlear implant surgery, including cochleostomy. Conventional cochlear implant surgery is typically performed via mastoidectomy with facial recess to identify and avoid damage to vital anatomic landmarks. To accomplish this procedure via a minimally invasive approach--without performing mastoidectomy--in a precise fashion, image-guided technology is necessary. With such an approach, surgical time and expertise may be reduced, and hearing preservation may be improved. INTERVENTIONS: Flat-panel volume computed tomography was used to scan 4 human temporal bones. A drilling channel was planned preoperatively from the mastoid surface to the round window niche, providing a margin of safety to all functional important structures (e.g., facial nerve, chorda tympani, incus). MAIN OUTCOME MEASURES: Postoperatively, computed tomographic imaging and conventional surgical exploration of the drilled route to the cochlea were performed. RESULTS: All 4 specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in 1 specimen--this was preoperatively planned as a narrow facial recess was encountered. CONCLUSION: Using flat-panel volume computed tomography for image-guided surgical navigation, we were able to perform minimally invasive cochlear implant surgery defined as a narrow, single-channel mastoidotomy with cochleostomy. Although this finding is preliminary, it is technologically achievable.
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0.30Impact points
[Image-guided minimal-invasive cochlear implantation--experiments on cadavers]
Laryngo- rhino- otologie. 02/2008; 87(1):18-22.
BACKGROUND: The accuracy of navigation systems can be improved significantly by using high-resolution flat panel-based Volume Computed Tomography (fpVCT) so that new surgical therapeutic concepts become feasible. A navigation-guided minimally-invasive cochleostomy places highest requirements on the ... [more] BACKGROUND: The accuracy of navigation systems can be improved significantly by using high-resolution flat panel-based Volume Computed Tomography (fpVCT) so that new surgical therapeutic concepts become feasible. A navigation-guided minimally-invasive cochleostomy places highest requirements on the accuracy of intraoperative navigation. METHODS: A flat-panel Volume Computed Tomograph (fpVCT) was used to scan four human temporal bones. The isometric voxel size was 200 microm. The preoperative planning was used to define an optimized drilling channel from the mastoid surface to the round window niche and the scala tympani providing a safety margin to critical anatomical structures such as facial nerve, chorda tympani, sigmoid sinus and posterior wall of auditory canal. The canal was drilled hand-operated with a navigated drill following the previously planned trajectory. Afterwards the drilled canal was imaged by fpVCT. Conventional dissection including mastoidectomy and posterior tympanotomy assured correct localization of the cochleostomy. RESULTS: Path planning took an average of 54 minutes (range 35-85 minutes). Installation took an average of 16 minutes (range 14-19 minutes). The drilling procedure itself took an average of 7.75 min (range 5-12 minutes.) The RMSE-values varied between 0.1 and 0.2 mm (Table 1). All four specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in one specimen--this was preoperatively planned as a narrow facial recess was encountered. The time needed for planning and system-installation could be reduced continuously. CONCLUSIONS: This feasibility study demonstrates that using current image-guided surgery technology in combination with fpVCT allows drilling of a minimally invasive channel to the cochlea with loco typico cochleostomy. The necessary accuracy of intraoperative navigation can be achieved by use of fpVCT (technical accuracy between 0.1 and 0.2 mm). Our results demonstrate the feasibility of a navigation-guided minimally-invasive cochleostomy loco typico. While we are enthused by this preliminary work, we recognize the barriers which exist in translation to clinical application. These include surgical issues (e.g. control of unexpected bleeding) and electrode issues (e.g. development of insertion tools).
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Conception and design of an automated insertion tool for cochlear implants.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference. 02/2008; 1:5593-5596.
Cochlear implants (CI) are electronic devices incorporating an electrode inserted into the human cochlea for direct electric stimulation of the auditory nerve. The implantation has become the standard treatment for patients with severe-to-profound sensorineural loss not aidable with conventional hea... [more] Cochlear implants (CI) are electronic devices incorporating an electrode inserted into the human cochlea for direct electric stimulation of the auditory nerve. The implantation has become the standard treatment for patients with severe-to-profound sensorineural loss not aidable with conventional hearing aids. The state of the art operative technique is a facial recess approach to the middle ear, following the opening of the scala tympani (cochleostomy) and insertion of the electrode array. The facial recess approach is applicable only by experienced surgeons and optimal CI results primarily depend on optimal electrode placement and minimal traumatic insertion. This also requires a certain amount of experience. Additionally several groups work on minimally-invasive approaches to the cochlea, resulting in the necessity to insert the implant via a keyhole access, which is not applicable with current techniques. This paper presents a mechatronic device for an automated insertion of the electrode array of a cochlear implant system. Being designed especially for minimally-invasive approaches, the tool is also applicable for regular facial recess approaches. Moreover the device allows reliable and repeatable insertion studies at synthetic models or cadaver specimen. The functionality of the tool is proofed with first experiments on a synthetic model.
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0.51Impact points
Homograft patch repair in carotid artery rupture.
VASA. Zeitschrift für Gefässkrankheiten. Journal for vascular diseases. 12/2007; 36(4):279-81.
The case of a 24-year-old man with a rupture of the left common carotid artery and history of intravenous drug abuse is presented. Due to absence of a suitable autologous vein segment the carotid bulb was repaired with a human allograftpatch.... [more] The case of a 24-year-old man with a rupture of the left common carotid artery and history of intravenous drug abuse is presented. Due to absence of a suitable autologous vein segment the carotid bulb was repaired with a human allograftpatch.
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0.65Impact points
Otogenic cerebellar abscess due to purulent labyrinthitis and defect of the superior semicircular canal and its propagation through the endolymphatic sac.
European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery. 09/2007; 264(8):955-8.
The otogenic cerebellar abscess still is one of the most dangerous complications of otitis media and implicates a high risk of mortality. Early diagnosis and therapy are decisive factors for the chances of rehabilitation. Radiologic imaging (CT/MRI) plays an important role. A broad-spectrum antibiot... [more] The otogenic cerebellar abscess still is one of the most dangerous complications of otitis media and implicates a high risk of mortality. Early diagnosis and therapy are decisive factors for the chances of rehabilitation. Radiologic imaging (CT/MRI) plays an important role. A broad-spectrum antibiotic according to antibiogram is indispensable. The type of surgical intervention depends on the cause and localization of the abscess. In this case the cerebellar abscess was a complication resulting from labyrinthitis, which was propagated through the endolymphatic duct and sac to the posterior fossa dura. Consequently, it could be cured ultimately only after petrosectomy and abscess drainage toward the mastoid cavity. It is mandatory to completely sanitize the infection surgically in order to avoid lethal complication especially in case of a delayed clinical course or recurrent symptoms of labyrinth involvement. Close interdisciplinary collaboration between ORL, neurosurgery and neuroradiology is desirable for successful therapy.
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1.45Impact points
Placement of intraventricular catheters using flexible electromagnetic navigation and a dynamic reference frame: a new technique.
Stereotactic and functional neurosurgery. 02/2007; 85(5):243-8.
BACKGROUND: Catheterization of narrow ventricles may prove difficult resulting in misplacement or inefficient trials with potential damage to brain tissue. MATERIAL AND METHODS: The application of a new module for navigated ventricular catheterization using flexible electromagnetic navigation and a ... [more] BACKGROUND: Catheterization of narrow ventricles may prove difficult resulting in misplacement or inefficient trials with potential damage to brain tissue. MATERIAL AND METHODS: The application of a new module for navigated ventricular catheterization using flexible electromagnetic navigation and a dynamic reference frame is presented. RESULTS: Navigated catheter placement was successful and accurate in a pilot study. Electromagnetic interferences had to be taken into consideration. CONCLUSION: Flexible electromagnetic navigation with a dynamic reference frame is a useful tool for catheter placement as it reduces the risk of misplacement or repeated catheterization trials.
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1.44Impact points
Increase of accuracy in intraoperative navigation through high-resolution flat-panel volume computed tomography: experimental comparison with multislice computed tomography-based navigation.
Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. 02/2007; 28(1):129-34.
HYPOTHESIS: High-resolution imaging, as provided by flat-panel-based volume computed tomography (fpVCT), could increase navigation accuracy and could therefore improve image-guided procedures or make novel navigated surgery concepts possible. BACKGROUND: Intraoperative navigation is an accepted tool... [more] HYPOTHESIS: High-resolution imaging, as provided by flat-panel-based volume computed tomography (fpVCT), could increase navigation accuracy and could therefore improve image-guided procedures or make novel navigated surgery concepts possible. BACKGROUND: Intraoperative navigation is an accepted tool in head and neck surgery. However, its use is limited in the lateral cranial base because of its low surgical accuracy. Surgical accuracy is substantially influenced by the resolution of the underlying data set. The fpVCT offers a resolution of nearly two times higher than multislice computed tomography (MSCT). Target registration error (TRE), as a measurement for surgical navigation accuracy, should decrease when navigation is based on fpVCT data sets. METHODS: An acrylic glass phantom with 37 fiducial points was scanned in a current MSCT and in an experimental fpVCT. Both data sets were imported in an optical navigation system. Five fiducial points were used for registration, and seven points were used for measuring TRE. The distance between the indicated pointer tip and the corresponding fiducial point in data set was measured as TRE. Registration and TRE measurement were repeated five times for each computed tomographic data set. Average TREs were calculated, and results were compared using t-test. RESULTS: The average TRE using MSCT (0.82 mm [standard deviation, 0.35 mm]) was significantly higher than that using fpVCT (0.46 mm [standard deviation, 0.22 mm]) (p < 0.01). CONCLUSION: Submillimeter surgical navigation accuracy is possible using high-resolution fpVCT. This could be highly beneficial in cranial base surgery navigation.
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0.65Impact points
