[Sentinel node mapping in head and neck squamous cell carcinoma]. / Sentinel-Node-Markierung bei Plattenepithelkarzinomen des Kopfes und Halses.

BACKGROUND: Commonly used staging procedures often cannot predict the absence of lymphatic micro- metastases in squamous cell carcinoma (SCC) of the head and neck. Therefore in many cases an elective neck dissection (ND) is necessary. In the surgical therapy of melanoma or breast cancer the presence of metastases can be evaluated securely by identification and examination of the sentinel lymph node (SLN). The type of surgical procedure is usually chosen in regard to the histopathological result. The present study evaluates the applicability of this concept for SCC of the head and neck. METHODS: Radioactive labeled micro-albumin particles were injected preoperatively around the tumor in 38 patients without proven metastases. Following the excision of the primary tumor the sentinel lymph node/s were detected and dissected and ND was completed. Histological examination of the tissue was performed to evaluate whether the SLN reflected the lymphatic status. RESULTS: In two cases (5.1 %) no SLN were detected. ND was completed in 32 cases. In nine cases (28.1 %) the SLN were infiltrated by the primary tumor. In 22 cases (68.8 %) SLN and ND revealed a N(0) stage. In one case (3.1 %) we could not identify a metastasis because of the anatomical closeness of the SLN to the primary. The negative predictive value was 96 %. CONCLUSION: Predictive value regarding metastases to the neck was higher with the detection of SLN than with conventional staging procedures. Whether the detection of a tumor-free SLN is an indication not to perform an elective neck dissection is a matter of discussion, especially under the aspect of the effective reduction of postoperative morbidity.

[Congenital hearing loss. Molecular genetic diagnosis of connexin genes and genetic counselling]. / Kongenitale Schwerhörigkeit. Molekulargenetische Diagnostik der Connexin-Gene und genetische Beratung.

BACKGROUND: About 50% of congenital non-syndromic hearing impairment is caused by genetic factors. Research on the genetics of deafness has revealed a vast number of relevant genes. Mutations in the GJB2 gene have been shown to be the most common in several populations. METHODS: Mutation analysis of the genes for connexin 26, 30 and 31 (GJB2, GJB6 and GJB3) was performed in 67 patients with profound hearing loss. RESULTS: Of the participants, 9% had two pathogenic mutations in the GJB2 gene. Pedigree information indicates that in these families further offspring have a 25% to a 100% chance of having hearing impairment. CONCLUSIONS: Patients with non-syndromic hearing impairment should be offered molecular diagnostics of the GJB2 gene. Genetic counseling is mandatory for mutation carriers in order to advise them on the individual consequences of the gene test results.

[Surgery of anterior skull base fractures]. / Operative Versorgung von Verletzungen der Frontorhinobasis.

BACKGROUND AND METHODS: The medical records of 144 patients that underwent surgery due to fractures of the anterior skull base between 1990 and 1999 were assessed retrospectively. Fracture causes, symptoms, fracture lines, surgical approaches and materials for dura repair were analyzed. RESULTS: The most frequent fracture causes were automobile (46.1%), recreational (24.8%) and occupational accidents (16.3%). While a decrease in automobile accidents was observed from 1996 (71.4%) to 1999 (33.3%), an increase in sports accidents was documented from 1990 (5.3%) to 1999 (16.7%). The most common accompanying injuries were CSF leakage (38.9%), loss of vision (28.5%) and intracranial bleeding (21.5%). The roof of the ethmoid sinus (79.7%) and the frontal sinus (anterior and posterior wall) (73.6%) were fractured most commonly. The lamina cribrosa was involved in 32.6%, the sphenoid sinus in 29.2% of the fractures. Most commonly the bitemporal Unterberger approach (75.7%) was used. To a lesser degree the uni- (13.9%) or bilateral (4.8%) Kilian approach, the reopening of the old wound (4.2%) and the endonasal approach (1.4%) were utilized. Conserved dura was applied for the closure of CSF leaks in 80.7%, periostal flaps in 20.7%, fascia lata in 14.8% and TachoComb in 8.2%. CONCLUSIONS: The results of this study indicate that posttraumatic fractures of the anterior skull base are declining in frequency. The most common causes for these injuries were automobile accidents but increasingly sports accidents. Typical fracture lines or combinations were not observed. In the period observed the bitemporal Unterberger approach and resorbable implant materials such as the coated collagen fleece TachoComb were increasingly used for surgery.

Regeneration of inner ear cells from stem cell precursors--a future concept of hearing rehabilitation?

The use of stem cells offers new and powerful strategies for future tissue development and engineering. Common features of stem cells are both their capacity for self-renewal and the ability to differentiate into mature effector cells. Since the establishment of embryonic stem cells from early human embryos, research on and clinical application of human ES cells belong to the most controversial topics in our society. Great hopes are based upon the remarkable observation that human ES cells can be greatly expanded in vitro, and that they can differentiate into various clinically important cell types. Recent advances in the cloning of mammals by nuclear transplantation provide new concepts for autologous replacement of damaged and degenerated tissues. In contrast, somatic stem cells of the adult organism were considered to be more restricted in their developmental potential. However, recent investigations suggest that somatic stem cells may have a wider differentiation potential than previously thought. In otology, initial experiments have revealed neural stem cell survival in cochlear cell cultures and under neurotrophin influence, neural stem cells seemed to develop into a neuronal phenotype. Further studies have to be carried out to investigate the full potential of stem cells as well as the molecular mechanisms that are involved in regulating cellular identity and plasticity. Clinically, advances in stem cell biology may provide a permanent source of replacement cells for treating human diseases and could open the development of new concepts for cell and tissue regeneration for a causal treatment of chronic degenerative diseases.

[Experimental investigations of CO2 laser application in middle ear ossicles]. / Experimentelle Untersuchungen zur Anwendung des CO2-Lasers an Gehörknöchelchenpräparaten.

BACKGROUND: During the last few years, several laser systems have been applied for procedures in middle ear surgery. In this study, we determined the technical parameters for the dissection of the middle ear ossicles with the CO(2) laser and analyzed the histological findings. METHODS: The malleus necks of 16 human temporal bones were dissected under standardized conditions using a CO(2) laser with a power output between 35 and 55 kW/cm(2). The specimens were fixed and histological probes of 50- micro m thickness were prepared. RESULTS: The laser outputs led to crater diameters from 0.14 to 0.55 mm. As an analogy between laser energy and thermal tissue destruction, three zones of thermal damage were differentiated: a cinder zone, a carbonization zone, and a zone of dehydration. The metrical dimensions of these zones did not show any correlation to the applied laser energy. CONCLUSIONS: The data of this study show that commercially available CO(2) lasers are sufficient for a safe and effective partial resection of middle ear ossicles using a power output of 35 kW/cm(2).

[Paranasal sinus surgery in chronic sinus disease and benign tumors indications, concepts and complications at a teaching institution]. / Chirurgische Eingriffe an den Nasennebenhöhlen bei Sinusitiden und benignen Tumoren. Indikationen, Konzepte und Komplikationen einer Weiterbildungseinrichtung.

BACKGROUND AND METHODS: The medical records of 635 patients that underwent paranasal sinus surgery for chronic sinus disease or benign tumors during a 6.5 year span were assessed retrospectively to evaluate the status of sinus surgery at a teaching institution. The parameters analyzed were indication for surgery, surgical approach, extent of the procedures and complications. RESULTS: The ratio between male and female patients was 2 : 1, with an average age of 44 (+/- 16) years. In 137 cases (21.5 %), revision surgery in patients previously treated at the University of Wuerzburg was necessary. In 80 cases (12.6 %), prior surgery had been performed elsewhere. The majority of the procedures (91.3 %) were carried out using endonasal techniques. External, transethmoid (6.5 %) or transmaxillar (2.2 %) approaches were chosen in 8.7 % of all cases, mainly when the preoperative diagnoses were mucoceles (65.2 %), benign tumors (40.9 %) or orbital complications (33.3 %). Surgery was assisted exclusively by the microscope in 78.7 %, solely by the endoscope in 15.9 % and with a combination of both optical tools in 5.4 % of all cases. The total rate of complications was 8.2 %. Minor complications were seen in 8.1 % of the endonasal and 4.9 % of the external transethmoid procedures. While no major complications occurred during endonasal or extranasal transmaxillar surgery, liquorrhoe was documented in three extranasal transethmoid procedures (7.3 %). Neither permanent impairment of vision, nor post-operative meningitis nor surgery-related mortality was observed in any case. CONCLUSION: The study gives an overview over the paranasal sinus surgeries performed at a teaching institution, independent of the experience of the surgeon. It confirms the results of previous investigations and indicates that endonasal sinus surgery is a reproducible and reliable procedure that can be safely applied at a teaching institution. The results also show that the indication for extranasal approaches is further reduced to the less invasive endonasal techniques.

[Histomorphometric assessment of spiral ganglion neurite outgrowth in vitro]. / Histomorphometrische Bestimmung des Wachstumsverhaltens von Spiralganglienzellneuriten in vitro.

BACKGROUND: During the last years, various groups of growth factors have been identified to influence spiral ganglion cell survival and neurite extension in the mammalian cochlea. To evaluate and compare the effects of different growth factors, a precise histomorphometrical analysis of neurite outgrowth patterns has to be applied. The here presented technique is compared to already published methods, that only approximately estimate the neurite length. METHOD: A software has been developed to analyse digitalised scans of spiral ganglion cells and to measure the length of the neurites. Therefore, the neurites are being separated in any given number of straight lines. The totals of these lines can then be added like a polygon. This polygon method was compared to a semi-quantitative procedure in which the neurite length was determined by concentric circles that were crossed by the neurites in a certain distance. The accuracy of both methods was analysed. Both methods were performed in 20 specimen of neonatal rat spiral ganglion cells after in vitro stimulation with neurotrophic factors. RESULTS: The semi-quantitative method has shown to involve a systematic error between +/- 10 to 15 %. The polygon method, on the contrary, has a systematic error of around +/- 1 %, which admits much more accurate measurement of spiral ganglion neurite outgrowth. CONCLUSION: With the described polygon method, spiral ganglion neurite growth patterns in cell culture studies can be characterised more precisely and, thus, helps to better differentiate the action domain of neurotrophic factors.

[Wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase influences neurotrophin-induced spiral ganglion neurite growth]. / Wortmannin, ein spezifischer Inhibitor der Phosphatidylinositol-3-Kinase, beeinflusst das neurotrophin-induzierte Wachstum von Spiralganglienneuriten.

BACKGROUND: Phosphatidylinositol 3-kinase (PI3K) is considered to be an important enzyme in cell signaling, mediating certain aspects of neurotrophin signals from the cell surface receptor to the nucleus. METHODS: The participation of PI3K in the mediation of neurotrophin-induced effects in the spiralganglion (SG) of neonatal rats was investigated in vitro. SG explants were stimulated with neurotrophin (NT)-3 and treated with Wortmannin, a specific inhibitor of PI3K. After fixation and immunhistochemical staining, the growth of the SG neurites was evaluated. RESULTS: Stimulation with NT-3 lead to significant increases in number and length of neurites, when compared to non-stimulated controls. Treatment of NT-3 stimulated SG explants resulted in a dose-dependent reduction of both parameters, whereas the neurite growth of non-stimulated control explants was not significantly influenced by the incubation with Wortmannin. CONCLUSIONS: The results demonstrate that neurotrophin-induced neurite growth from SG explants can be modulated with the PI3K inhibitor Wortmannin and indicate that PI3K is a key enzyme in the mediation of NT-3 effects in cochlear neurons. These observations together with results of previous studies suggest that the activation of PI3K as well as Ras and MEK are essential for neurite growth in cochlear neurons. Further knowledge of cell signaling mechanisms influencing SG neurite growth could lead to new therapeutical strategies for the treatment of inner ear diseases.

The disintegrin kistrin inhibits neurite extension from spiral ganglion explants cultured on laminin.

The influence of laminin-1 (LN) and tenascin-C (TN), extracellular matrix molecules expressed spatially and temporally along the neural growth route from spiral ganglion (SG) neurons to the cochlear sensory cells, was evaluated in cultured SG explants from postnatal day 4 rats. Increasing concentrations of LN resulted in a strong, dose-dependent increase in the length of neurites and in a higher number of neural processes, while varying TN concentrations had relatively minor effects on both parameters. The results suggest differential receptor activation by LN and TN. When explants grown on LN were treated with Kistrin, an inhibitor of the alphavbeta3 integrin, the LN-induced increase in neurite length was reduced in a dose-dependent manner. However, the number of extending neurites was not affected, indicating that different receptors mediate this response, perhaps by increasing neuronal survival.

Growth factors influence growth and differentiation of the middle ear mucosa.

OBJECTIVE: Otitis media is a major cause of morbidity in pediatric and adult patients. This inflammatory condition is characterized by mucosal hyperplasia that is thought to be mediated by the complex actions of growth factors and their respective receptors. It was the purpose of this study to determine which growth factors might be responsible for the growth and differentiation of the middle ear epithelium during otitis media. STUDY DESIGN: The effect of several growth factors on the expansion and differentiation of normal middle ear mucosa was evaluated in tissue culture. MATERIALS AND METHODS: Explants of normal rat middle ear mucosa were exposed in vitro to six different growth factors known to influence epithelial cells in other tissues: epidermal growth factor, amphiregulin, betacellulin, heregulin-alpha, keratinocyte growth factor, and hepatocyte growth factor. RESULTS: After 12 days, the growth and level of cytokeratin expression were analyzed for each of the explant outgrowths. Each factor appeared to have a significant, concentration-dependent effect on either the growth or differentiation of the cultured middle ear epithelial cells. CONCLUSION: The results suggest that several of the tested growth factors may play a significant role in controlling hyperplasia of the middle ear mucosa during otitis media.

In vivo adenoviral transduction of the neonatal rat cochlea and middle ear.

Virally mediated gene transfer to the adult mammalian ear appears to be a powerful strategy to investigate gene function in the auditory system and to develop new therapeutic treatment for hearing impaired patients. However, there has been little work done in the neonatal middle and inner ear. In this study, a recombinant adenoviral (AdV) vector was used for gene transfer of a beta-galactosidase (beta-gal) reporter gene to the neonatal middle ear and cochlea of 5 day old rats. For transduction of middle ear, AdV was injected through the tympanic membrane into the tympanic cavity. Three and 7 days later, strong expression of beta-gal was observed in epithelial cells of the mucosa, but not in the underlying stroma or mesenchyme. There was little or no infiltration of leukocytes. No expression of beta-gal was detected inside the cochlea or vestibular system. When AdV was injected into the basal turn of the cochlea, high levels of beta-gal expression were observed in cells lining the perilymphatic space and in parts of the spiral ligament 3, 7 and 21 days later. Spiral ganglion cells did not express beta-gal. However, virally mediated gene transfer was observed in some cells of the organ of Corti. A moderate infiltration of leukocytes into the labyrinth was observed, but no vestibular or auditory dysfunction. These results demonstrate that neonatal middle ear and cochlear cells can be successfully transduced with an AdV vector in vivo, without obvious morphological signs of inflammation or cellular damage. AdV vectors provide a tool for investigation of the role of genes in influencing the development of middle and inner ear structures. Virally mediated expression of protective genes could also be used to rescue hair cells or spiral ganglion cells from congenital degeneration or damage.

Ras/MEK but not p38 signaling mediates NT-3-induced neurite extension from spiral ganglion neurons.

Neurotrophin (NT)-3 is expressed in the neuronal target tissue of the developing rat cochlea and has been shown to promote the survival and neurite outgrowth of spiral ganglion (SG) neurons, suggesting a role for this protein during the innervation of the organ of Corti. In other neurons, NT-3 can mediate neuritogenesis and survival via a number of intracellular signal pathways. To date, the intracellular transduction pathways involved in the mediation of NT-3 effects have not been investigated in SG neurons. To determine whether the activities of NT-3 on SG neurons are dependent on the activation of mitogen-activated protein kinase kinases (MEK)/extracellular-signal-regulated kinases (ERK), Ras, and/or p38, SG explants from postnatal-day 4 rats were cultured with NT-3 and increasing concentrations of the MEK inhibitor U0126, the Ras farnesyl-transferase inhibitor (FTI)-277, and the p38 inhibitor SB203580. After fixation and immunocytochemical labeling, neurite growth was evaluated. A dose-dependent decrease of the effects of NT-3 on length and number of processes was observed in the U0126- and FTI-277-treated SG neurons. In contrast, SB203580 had no significant effect on NT-3-mediated stimulation of neurite growth, in terms of either number or length. The results suggest that NT-3 effects on SG neurons are mediated primarily by the Ras/MEK/ERK signaling pathway.

[Effect of fibroblast growth factor-1 (FGF-1) on spiral ganglion cells of the mammalian cochlea]. / Die Wirkung von Fibroblastenwachstumsfaktor-1 (FGF-1) auf Spiralganglienzellen der Säugetiercochlea.

Transient expression by hair cells, increasing levels of FGF-1 mRNA in neonatal rat spiral ganglion neurons and strong expression in adulthood, make FGF-1 a candidate to be associated with development and maintenance of the mammalian spiral ganglion. To test this hypothesis, dissociated spiral ganglion cells from 5 day old rats were cultured in the presence of FGF-1 at 100 ng/ml plus heparan sulfate proteoglycans (HSPG) at 500 ng/ml for 72 hours. Spiral ganglion cells incubated with FGF-1/HSPG achieved an average neurite length of 323 microns while control cells gained an average neurite length of 203 microns. The results of this study are consistent with our previous findings in whole spiral ganglion explants (3) where FGF-1 incubation significantly stimulated neurite outgrowth at about the same range. However, stimulation of neurite outgrowth in dissociated spiral ganglion cells suggests that FGF-1 directly binds to FGF receptors on the surface of spiral ganglion neurons and/or neurites instead of acting via intermediate cells such as glia. Since FGF receptor mRNA was found to be expressed only at very low levels in neonatal spiral ganglion neurons (7) it is possible that the receptors are highly localized, perhaps to neurite growth cones. Alternatively, an unknown FGF receptor or splice variant may be expressed in these cells. Adequate FGF-1 application to the human inner ear may stimulate spiral ganglion cell survival and neurite extension after hair cell loss in patients suitable for cochlear implant treatment. By creating a closer contact between spiral ganglion cells and the electrode, FGF-1 might also improve the efficacy of cochlear implants.

[An anesthesia technique for experimental studies and microsurgical ear interventions in newborn rodents]. / Eine Narkosetechnik für experimentelle Untersuchungen und mikrochirurgische Eingriffe am Ohr neugeborener Nagetiere.

BACKGROUND: Experimental investigations on laboratory animals usually require sufficient anesthesia with adequate analgesia and sedation. The technique used should be reliable and easily controllable by the investigator. Here, we present a technique for anesthesia to facilitate invasive and noninvasive investigations in newborn rats and mice. METHODS: Using a custom made breathing mask, anesthesia was induced in these animals with inhalation of gaseous nitrous oxide-oxygen (equal volume at 1 l/min) and halothane (3% by volume). To maintain anesthesia, halothane insufflation was reduced to 1-1.5% by volume. After completion of the experimental procedure, the application of the inhalative gases was determined and substituted by oxygen at 2 l/min. Anesthesia was performed in spontaneously breathing animals. Heart frequency and oxygenation were monitored using a commercially available pulse oximeter. RESULTS: Using the above described technique in neonatal rodents, microsurgery of the ear was performed without signs of pain or major bleeding. Auditory brain stem responses were recorded clearly and reproducible. CONCLUSIONS: This method represents a noninvasive, well tolerated and easy controllable anesthetic procedure which has proven to provide a sufficient and reliable sedation in neonatal rodents for surgical and nonsurgical investigations.

Focal delivery of fibroblast growth factor-1 by transfected cells induces spiral ganglion neurite targeting in vitro.

Sensory cells in the cochlea of the rat transiently express acidic fibroblast growth factor (FGF-1) during the developmental period of terminal innervation in the sensory epithelium. To explore the potential role of FGF-1 in terminal innervation events, the response of cochlear ganglion neurons to FGF-1 was evaluated in culture. Explants from the spiral ganglion of postnatal day 5 rats were cultured in the presence of exogenous FGF-1, with or without heparin. FGF-1 in the culture medium produced a dose-dependent increase in the number and length of neurites produced by spiral ganglion neurons, a response that was enhanced by heparin. To assess the effects of FGF-1 produced by a focal, cellular source, additional explants were cocultured with 3T3 cell transfectants that secrete FGF-1. Neurites that came into contact with FGF-1 secreting cells branched, formed bouton-like terminal swellings on the surface of the transfectants, and stopped extending. The results suggest that FGF-1 may stimulate neurite extension into the sensory epithelium of the cochlea and that focal production of FGF-1 may contribute to the formation of contacts on sensory cells by developing neurites.

[Extramedullary plasmacytoma--manifestation in petrous bone]. / Extramedulläre Plasmozytom--Manifestation am Felsenbein.

BACKGROUND: Extramedullary plasmocytoma of the temporal bone is a rare neoplastic disorder. Only a very few cases are described in the world literature. CASE: We report on a patient who presented with the clinical signs of a glomus jugular tumor. Postoperative histological evaluation revealed an extramedullary plasmocytoma of the temporal bone. CONCLUSION: If a glomus tumor is suspected, histological investigation appears necessary if surgery is not possible or is contraindicated.