Automatic Registration for Navigation at the Anterior and Lateral Skull Base.

OBJECTIVE: Navigation systems create a connection between imaging data and intraoperative situs, allowing the surgeon to consistently determine the location of instruments and patient anatomy during the surgical procedure. The best results regarding the target registration error (measurement uncertainty) are normally demonstrated using fiducials. This study aimed at investigating a new registration strategy for an electromagnetic navigation device. METHODS: For evaluation of an electromagnetic navigation system and comparison of registration with screw markers and automatic registration, we are calculating the target registration error in the region of the paranasal sinuses/anterior and lateral skull base with the use of an electromagnetic navigation system and intraoperative digital volume tomography (cone-beam computed tomography). We carried out 10 registrations on a head model (total n = 150 measurements) and 10 registrations on 4 temporal bone specimens (total n = 160 measurements). RESULTS: All in all, the automatic registration was easy to perform. For the models that were used, a significant difference between an automatic registration and the registration on fiducials was evident for just a limited number of screws. Furthermore, the observed differences varied in terms of the preferential registration procedure. CONCLUSION: The automatic registration strategy seems to be an alternative to the established methods in artificial and cadaver models of intraoperative scenarios. Using intraoperative imaging, there is an option to resort to this kind of registration as needed.

Robotic cochlear implantation: feasibility of a multiport approach in an ex vivo model.

PURPOSE: A recent clinical trial has shown the feasibility of robotic cochlear implantation. The electrode was inserted through the robotically drilled tunnel and an additional access through the external auditory canal was created to provide for means of visualization and manipulation. To obviate the need for this additional access, the utilization of multiple robotically drilled tunnels targeting the round window has been proposed. The objective of this study was to assess the feasibility of electrode insertion through a robotic multiport approach. METHODS: In four ex vivo human head specimens (left side), four trajectories through the facial recess (2x) and the retrofacial and suprameatal region were planned and robotically drilled. Optimal three-port configurations were determined for each specimen by analyzing combinations of three of the four trajectories, where the three trajectories were used for the electrode, endoscopic visualization and manipulative assistance. Finally, electrode insertions were conducted through the optimal configurations. RESULTS: The electrodes could successfully be inserted, and the procedure sufficiently visualized through the facial recess drill tunnels in all specimens. Effective manipulative assistance for sealing the round window could be provided through the retrofacial tunnel. CONCLUSIONS: Electrode insertion through a robotic three-port approach is feasible. Drill tunnels through the facial recess for the electrode and endoscope allow for optimized insertion angles and sufficient visualization. Through a retrofacial tunnel effective manipulation for sealing is possible.

Taking a fresh look at the skull base in otorhinolaryngology with web-based simulation: Student's Interactive Skull-Base Trainer (SISTer).

IMPORTANCE: The increasing amount of medical knowledge and necessity for time-effective teaching and learning have given rise to emerging online, or e-learning, applications. The base of the skull is a challenging anatomic area in the otorhinolaryngology (ORL) department-for both students and lecturers. Technology-enhanced learning might be an expedient approach to benefit both learners and lecturers. OBJECTIVE: To investigate and create for advanced medical students a self-assessed adaptive e-learning application for the skull base within our curriculum of otolaryngology at the University Medical Center of Heinrich Heine University, Düsseldorf, Germany. DESIGN, SETTING, AND PARTICIPANTS: Pilot approach with prospective evaluation of a newly implemented web-based e-learning simulation. The e-learning application (Student's Interactive Skull-Base Trainer) was made accessible as an elective course to a total of 269 enrolled medical students during the first 2 semesters after web launch. INTERVENTIONS: Spatiotemporal independent e-learning application for the skull base. MAIN OUTCOMES AND MEASURES: Self-assessed evaluation with focus on general acceptance and personal value as well as usage data analysis. RESULTS: The application was well accepted by the learners. More than 80% of the participating students found the application to be a beneficial tool for enhancing their analytical and clinical problem-solving skills. Although the general matter of the skull base seemed to be of lesser interest, the concept of anchored instructions with the use of high-end, interactive, multimedia-based content was considered to be particularly suitable for this challenging topic. Most of the students would have appreciated an extension of optional e-learning modules. CONCLUSIONS AND RELEVANCE: With this pilot approach we were able to implement a useful and now well-accepted tool for blended learning. We showed that it is possible to raise interest even in this very specialized subspecialty of ORL with overall individual learning benefit for the students. There is a demand for more e-learning and web-based simulation to support the existing curricula in a hybrid, blended way.

An ultrasound-based navigation system for minimally invasive neck surgery.

Future minimally invasive neck surgery requires a navigation system adapted to the actual intra-operative bedding of the patient. The detection of the bedding-caused tissue shift is essential for a safe orientation for the surgeon new endoscopic operation procedures in neck surgery. It is essential to visualize the relation between important anatomic landmarks and operation instruments at any time. Within the scientific project SACAS we focus on developing an ultrasound supported navigation system based on preoperative imaging which considers the intra-operative tissue shift. A rotatable, flexible neck-model provides the basis for our analysis to evaluate the tissue shift and to invent the new navigation system for endoscopic neck surgery. The total registration error of the system was 2 mm.

Rotatable flexible neck-model for the evaluation of minimally invasive operation procedures with the help of an ultrasound-based navigation system.

Future minimally invasive neck surgery requires a navigation system adapted to the actual intraoperative bedding of the patient. The detection of the bedding-caused tissue shift is essential for a safe orientation for the surgeons' new endoscopic operation procedures in neck surgery. It is essential to visualize the relation between important anatomic landmarks and operation instruments at any time. Within the scientific project SACAS we focus on developing an ultrasound supported navigation system based on preoperative imaging which considers the intraoperative tissue shift. A rotatable, flexible neck-model provides the basis for our analyses to evaluate the tissue shift and to invent the new navigation system for endoscopic neck surgery. The total registration error of the system was 2 mm.

Comparison of the nasal release of IL-4, IL-10, IL-17, CCL13/MCP-4, and CCL26/eotaxin-3 in allergic rhinitis during season and after allergen challenge.

BACKGROUND: Allergic rhinitis is an inflammatory disease characterized by local overproduction of type 2 cytokines and tissue eosinophilia. Recent research suggests the involvement of additional cytokines such as IL-17, chemokine (C-C motif) ligand (CCL) 26/eotaxin-3, and CCL13/monocyte chemoattractant protein-4 (MCP-4) in its pathophysiology. Furthermore, bronchial epithelial cells treated with IL-17 and type 2 cytokines distinctively up-regulated eotaxin-3 gene expression. In this study we investigated the kinetics of IL-4, IL-10, IL-17, eotaxin-3, and MCP-4 in seasonal allergic rhinitis volunteers after nasal allergen challenge (NAC) and their release during natural pollen exposure. METHODS: The nasal lavages of 15 symptomatic allergic and 14 nonallergic subjects were collected during the pollination season. Additionally, six allergic subjects underwent a single unilateral nasal allergen and control challenge out of season, and nasal secretions were collected. Levels of IL-4, IL-10, IL-17, eotaxin-3, and MCP-4 in nasal lavages and secretions were measured using an electrochemiluminescent assay. RESULTS: After NAC, allergic subjects had a significant immediate response of nasal symptoms as well as a significant increase at 5 hours of IL-4, IL-10, and IL-17 and at 2, 5, and 24 hours significantly raising levels of eotaxin-3. IL-17 and eotaxin-3 concentrations at 5 hours were correlated (r = 0.94; p = 0.005). During natural pollen exposure, barely detectable levels of IL-17 in allergic subjects were also correlated with eotaxin-3 (r = 0.62; p = 0.01). Eotaxin-3 and MCP-4 levels were significantly elevated 9- or 3.7-fold, respectively, and IL-10 and, unexpectedly, IL-4 were significantly lower in allergic subjects compared with nonallergic subjects. CONCLUSION: Nasal IL-17, MCP-4, and, possibly, eotaxin-3 may aggravate and IL-10 may alleviate nasal mucosal allergy.

The release of IL-31 and IL-13 after nasal allergen challenge and their relation to nasal symptoms.

BACKGROUND: IL-31, a recently discovered member of the gp130/IL-6 cytokine family, is mainly expressed by human mast cells and T helper type 2 cells. IL-31 is a key trigger of atopic dermatitis. Recent studies also suggest a role of IL-31 in the pathogenesis of other allergic diseases including allergic rhinitis. In the present study we studied the release of IL-31 and IL-13 in allergen-challenged allergic rhinitis patients. METHODS: Seven seasonal allergic volunteers underwent unilateral nasal provocation with allergen (and a control challenge) with the disc method out of the allergy season. Nasal symptom scores (rhinorrhea, itching, sneezing, obstruction) and bilateral nasal secretions were quantified before and after allergen provocation. IL-13 and IL-31 in nasal secretions and serum were measured by electrochemiluminescent immunoassay or ELISA, respectively. RESULTS: Nasal allergen challenge induced the typical clinical symptoms and physiological changes. IL-31 and IL-13 in nasal secretions increased in four and five, respectively, volunteers at 5 h after allergen but not after control challenge. We observed correlation trends between nasal IL-31 concentrations and IL-13 concentrations (r = 0.9, p = 0.002), and IL-31 contents and symptom scores (r = 0.9, p = 0.013) 5 h after allergen provocation. No IL-31 could be detected contralaterally or systemically in the sera. CONCLUSIONS: The observed local upregulation of IL-31 mainly during the late phase reaction after nasal allergen challenge suggests a role of IL-31 in allergic rhinitis. In which way IL-31 modulates the inflammatory reaction and type 2 responses in allergic rhinitis remains to be investigated.

Surgical management of retropharyngeal abscesses.

CONCLUSION: Retropharyngeal abscess (RPA) is a rare, potentially life-threatening disease, requiring appropriate otorhinolaryngologic as well as radiologic diagnostics, and medical and surgical intervention by a transoral, transcervical or transnasal approach in a multidisciplinary setting. OBJECTIVES: The risks and benefits of surgical intervention in patients with RPA were assessed. The main outcome measure was the clinical resolution of the abscess. PATIENTS AND METHODS: A retrospective chart review was performed at a tertiary care university hospital over a period of 28 months. Eleven patients aged 1 to 68 years with the diagnosis of RPA were included. RESULTS: All patients presented with restricted cervical mobility and all patients had CT and/or MRI scan on admission. The mean abscess volume was 9.4 cm(3). Surgical intervention was performed in all cases, including transoral (n=5), transcervical (n=3) or combined transoral and transcervical (n=2) drainage. In one patient RPA close to the skull base was drained by an MRI-guided transnasal approach. All patients recovered; however, there was one recurrence and in one case surgical tracheotomy was unavoidable during the course of disease. Growth of streptococcal species was verified in six of the examined abscesses. Abscessing lymphadenitis, infection of a cervical cyst, and previous ganglionar local opioid analgesia treatment were identified as causative factors.

Clinical features of paraganglioma syndromes.

Head and neck paragangliomas (HNPs) and pheochromocytomas are rare tumors. Sporadic and hereditary forms are recognized. Four different paraganglioma syndromes (PGLs 1-4) have been described: PGL 1 is associated with mutations of the succinate dehydrogenase (SDH) subunit D (SDHD) gene; PGL 3 is caused by SDHC gene mutations; PGL 4 is caused by SDHB gene mutations; the susceptibility gene for PGL 2 is unknown. The objective of this study is to review distinct clinical features of the different PGLs. An international registry for HNPs was founded in Freiburg, Germany, in 2000. The data presented in this article have been acquired from registered HNP patients who have been screened for mutations of the genes SDHB, SDHC, and SDHD. Approximately 30% of apparent sporadic HNPs are caused by a germline mutation in one of these genes. Patients with PGL 1 or 4 have a very high lifetime risk of developing HNPs as well as thoracic and abdominal pheochromocytomas. Compared with sporadic HNPs, tumors developing in SDHB, SDHC, and SDHD mutation carriers arise at a significantly younger age. The SDHB mutations are associated with a high percentage of malignant paraganglionic tumors. We recommend molecular genetic screening of all HNP patients for SDHB, SDHC, and SDHD gene mutations. Mutation carriers must be screened for paraganglial tumors in the head, neck, thorax, and abdomen. Appropriately timed surgical intervention will minimize disease-specific morbidity and mortality. Lifelong follow-up is mandatory.

Juxtacondylar approach in temporal paraganglioma surgery: when and why?

As it became clear that patients with paraganglioma (PGL) syndromes had a higher risk of multifocal tumors, we changed our surgical strategy to avoid the possibility of bilateral cranial nerve paralysis. The juxtacondylar approach offers advantages for some jugular foramen tumors, including types C and D temporal PGLs. This approach allows exposure of the jugular foramen without skeletonizing or transposing the facial nerve. It improves the surgeon's ability to distinguish between the pars vascularis and the pars nervosa at the jugular foramen, and it helps to save functioning of the lower cranial nerves. There is already considerable experience using the juxtacondylar approach for patients suffering from schwannomas and meningiomas involving the jugular foramen. Some limitations have been noted for using the juxtacondylar approach with jugular PGLs that are related to their vascular nature. In this article we demonstrate its use for the management of eight patients with locally advanced temporal PGLs and how it can be combined with an infratemporal fossa approach.

High precision cochleostomy by use of a pulsed CO2 laser - an experimental approach.

A precise cochleostomy is a crucial step in cochlear implantation, particularly if residual hearing is to be preserved. A contactless ablation of the promontory bone by a pulsed CO(2) laser system seems to be a promising approach. The bone is removed by a scan head controlled laser beam in sequential scan cycles with a pulse rate of 50-100 mus. Digital picture analysis and pattern detection are used to identify the membranous lining of the cochlea. We achieved a bone ablation in a micrometer range per scan cycle with the laser. A perforation of the promontory bone could be detected by automatic pattern detection. The enhancement of automatic pattern detection can lead to a minimally invasive, function-preserving laser cochleostomy.

New strategies for high precision surgery of the temporal bone using a robotic approach for cochlear implantation.

The aim of the study was to demonstrate a collision-free trajectory of an instrument through the facial recess to the site of planned cochleostomy guided by a surgery robot. The indication for cochlear implantation is still expanding toward more substantial residual hearing. A cochleostomy as atraumatic as possible will influence the preservation of inner ear function. The employment of a highly precise instrument guidance using a robot could represent a feasible solution for a constant reproducible surgical procedure. Screw markers for a point-based registration were fixed on a human temporal bone specimen prepared with a mastoidectomy and posterior tympanotomy. A DICOM dataset has been generated thereof in a 64-multislice computer tomography (CT). A virtual trajectory in a 3D model has been planned representing the path of instrumentation toward the desired spot of cochleostomy. A 1.9-mm endoscope has been mounted onto the robot system RobaCKa (Staeubli RX90CR) to visualize this trajectory. The target registration error added up to 0.25 mm, which met the desirable tolerance of <0.5 mm. A collision-free propagation of the endoscope into the tympanic cavity via the facial recess has been performed by the robot and the spot of cochleostomy could be visualized through the endoscope. Using a DICOM dataset of a high-resolution CT and a robot as a positioning platform for surgical instruments could be a feasible approach to perform a highly precise and constant reproducible cochleostomy. Furthermore, it could be a crucial step to preserve substantial residual hearing in terms of expanding the indications for cochlear implantation.

Navigation as a tool to visualize bone-covered hidden structures in transfrontal approaches.

A retrospective analysis of 10 patients was performed to evaluate navigation systems in extranasal frontal skull base surgery. When performing a craniotomy following a bicoronal skin incision, the surgeon has to calculate the extent of the frontal sinus to avoid unnecessary damage to the dura or mucoceles later. Due to surgical morbidity including compression of the frontal lobe, many skull base surgeons have refused to use such an approach. Malformation or bone-destruction complicates the identification of the borders and increases the risk of side-effects. Navigation systems can be an alternative for calculating the frontal sinus outlines during surgery. In the authors' surgical procedure two different navigation systems were used. Conventional surgery using the transfrontal, transbasal or subcranial approach consisting of trepanation and craniotomy were performed, while the navigated surgical procedure was evaluated. The analysis showed that computer-assisted surgery (CAS) is applicable to extranasal frontal skull base surgery. In comparison to X-ray beam-controlled craniotomy, CAS is beneficial as it constitutes a noninvasive instrument of quality management. Furthermore, the analysis indicated that under the guidance of a navigation system a precise pre-surgical simulation is available in order to perform an optimal craniotomy and reconstruction of the frontal skull base.

Amyloid tumor of the larynx associated with plasma cell infiltration: differential diagnosis.

Localized amyloidosis of the larynx is uncommon, accounting for fewer than 1% of all benign laryngeal tumors. We report 2 cases of laryngeal amyloidosis in which dense plasma cell infiltrates were found in the vicinity of the amyloid deposits; in view of this finding, we suspected a hematologic disease--plasmacytoma in particular: However, molecular genetic analysis did not demonstrate any light-chain restriction, indicating that the plasma cells were of polyclonal origin and therefore consistent with chronic inflammation. We also discuss the available literature with respect to diagnostic and therapeutic procedures in patients with amyloidosis of the upper airway.

Retroauricular skin flap and primary Z-plasty for donor site closure in partial ear reconstruction.

Helical rim defects are noticeable and may well need reconstruction, especially in men. A method for reconstructing this type of defect together with primary donor site closure by Z-plasty is described. To close partial helical rim defects, a retroauricular caudally based rotational skin flap is performed to cover a conchal cartilage graft from the same ear that is harvested first and sutured into place to remodel the helical rim. To primarily close the donor site defect a retroauricular Z-plasty was developed which easily allowed primary closure of the donor site. The technique described here is straightforward, safe and reproducible. The Z-plasty approach for closing the donor site is useful, since the slight disturbance of the hairline is well hidden retroauricularly. This technique can be considered as a single-stage repair modality for the reconstruction of helical rim defects within primary donor site closure.

18F-DOPA positron emission tomography for the detection of glomus tumours.

The purpose of this study was to evaluate (18)F-DOPA whole-body positron emission tomography ((18)F-DOPA PET) as a biochemical imaging approach for the detection of glomus tumours. (18)F-DOPA PET and magnetic resonance imaging (MRI) were performed in ten consecutive patients with proven mutations of the succinate dehydrogenase subunit D ( SDHD) gene predisposing to the development of glomus tumours and other paragangliomas. (18)F-DOPA PET and MRI were performed according to standard protocols. Both methods were assessed under blinded conditions by two experienced specialists in nuclear medicine (PET) and diagnostic radiology (MRI). Afterwards the results were compared. A total of 15 lesions (four solitary and four multifocal tumours, the latter including 11 lesions) were detected by (18)F-DOPA PET. Under blinded conditions, (18)F-DOPA PET and MRI revealed full agreement in seven patients, partial agreement in two and complete disagreement in one. Eleven of the 15 presumed tumours diagnosed by (18)F-DOPA PET were confirmed by MRI. The correlation of (18)F-DOPA PET and MRI confirmed three further lesions previously only detected by PET. All of them were smaller than 1 cm and had the signal characteristics of lymph nodes. For one small lesion diagnosed by PET, no morphological MRI correlate could be found even retrospectively. No tumour was detected by MRI that was negative on (18)F-DOPA PET. All tumours diagnosed by MRI showed a hyperintense signal on T2-weighted images and a distinct enhancement of contrast medium on T1-weighted images. The mean tumour size was 1.5+/-0.5 cm. (18)F-DOPA PET seems to be a highly sensitive metabolic imaging procedure for the detection of glomus tumours and may have potential as a screening method for glomus tumours in patients with SDHD gene mutations.

Germ-line mutations in nonsyndromic pheochromocytoma.

BACKGROUND: The group of susceptibility genes for pheochromocytoma that included the proto-oncogene RET (associated with multiple endocrine neoplasia type 2 [MEN-2]) and the tumor-suppressor gene VHL (associated with von Hippel-Lindau disease) now also encompasses the newly identified genes for succinate dehydrogenase subunit D (SDHD) and succinate dehydrogenase subunit B (SDHB), which predispose carriers to pheochromocytomas and glomus tumors. We used molecular tools to classify a large cohort of patients with pheochromocytoma with respect to the presence or absence of mutations of one of these four genes and to investigate the relevance of genetic analyses to clinical practice. METHODS: Peripheral blood from unrelated, consenting registry patients with pheochromocytoma was tested for mutations of RET, VHL, SDHD, and SDHB. Clinical data at first presentation and follow-up were evaluated. RESULTS: Among 271 patients who presented with nonsyndromic pheochromocytoma and without a family history of the disease, 66 (24 percent) were found to have mutations (mean age, 25 years; 32 men and 34 women). Of these 66, 30 had mutations of VHL, 13 of RET, 11 of SDHD, and 12 of SDHB. Younger age, multifocal tumors, and extraadrenal tumors were significantly associated with the presence of a mutation. However, among the 66 patients who were positive for mutations, only 21 had multifocal pheochromocytoma. Twenty-three (35 percent) presented after the age of 30 years, and 17 (8 percent) after the age of 40. Sixty-one (92 percent) of the patients with mutations were identified solely by molecular testing of VHL, RET, SDHD, and SDHB; these patients had no associated signs and symptoms at presentation. CONCLUSIONS: Almost one fourth of patients with apparently sporadic pheochromocytoma may be carriers of mutations; routine analysis for mutations of RET, VHL, SDHD, and SDHB is indicated to identify pheochromocytoma-associated syndromes that would otherwise be missed.