Optical coherence tomography and confocal laser scanning microscopy as non-invasive tools in the diagnosis of sinonasal inverted papilloma: a pilot study.

Optical coherence tomography (OCT) and confocal laser scanning microscopy (CLSM) are light-based imaging techniques that allow for a visualization of microscopic tissue properties in vivo. Our study was to examine whether they allow for differentiation of inverted papilloma (IP) from nasal polyps (NP). Five cases of IP and NP, respectively, were investigated intraoperatively with OCT and CLSM. Biopsies were taken of the investigated area and were analyzed ex vivo with OCT and CLSM and then underwent HE-staining for standard light microscopy. On OCT images, IP showed the characteristic inverted character of the epithelium, that was thicker with a high degree of variability of thickness compared to the thin and homogenous epithelium of NP. In addition, the characteristic stromal edema of NP could be visualized. On CLSM images, the typical epithelial invaginations of IP appeared as crypts, while in NP the highly organized cylindric epithelium could be visualized. In vivo, OCT acquired images of sufficient quality to visualize these characteristics, while CLSM did not. Our study demonstrates that OCT and CLSM can distinguish IP from NP. Further technical development is required to apply the techniques clinically to guide intranasal biopsies or even to make them dispensable.

Spike detection and sorting using PARAFAC2 method.

In this contribution we introduce the Parallel Factor 2 (PARAFAC2) analysis as a novel method for the simultaneous detection and classification of neural action potentials. In order to measure these action potentials (spike signals), stem cell derived neuronal cells are cultivated on the surface of a Micro Electrode Array (MEA). Here, the neuronal cells produce ion currents, which can be measured as extracellular electric potentials. Whenever a cell or a group of cells produces ion currents, either spontaneously or evoked by a stimulus, a spike signal can be measured by the electrodes of the MEA. Stimulated cells produce spikes and groups of spikes (bursts) which propagate in space over the MEA. In the recorded data, different source types (e.g., cells which respond directly to external stimuli and cells which are triggered by other neural cells) are characterized by different spike shapes. The proposed PARAFAC2 method is able to separate these spike shapes (sources) in time, frequency and space (channels) enabling an improved performance in noisy scenarios. Furthermore, PARAFAC2 allows for a causality analysis on the measured spike signals (i.e. the identification of different signal paths). Thereby, the PARAFAC2 decomposition is able to exploit the multi-dimensional structure of the MEA data.

[Effect of fenestration of the cochlea on the vibration of the round window membrane]. / Effekt der Promontorialfensterung auf die Schwingung der Rundfenstermembran - experimentelle Studie.

Drilling a promontory window and coupling an FMT into the scala tympani may be a surgical alternative to stapes surgery in obliterative tympanosclerosis. Aim of this experimental study on human temporal bones was to measure changes of the acoustic transfer function from the tympanic membrane to the round window membrane after drilling a promontory window and insertion of a floating mass transducer.Laser vibrometry and acoustic measurements were performed on 11 temporal bone preparations equipped with a microphone attached to the round window. Calibrations were carried out to allow determination of SPLs affecting the cochlea after drilling a promontory window leaving the membranous inner ear intact and after insertion of an FMT into the cavity (with or without slight pressure).Drilling a promontory window does influence the transfer function. Insertion of the FMT with additional slight pressure further changes the transfer function.The presence of a promontory window changes the acoustic transfer function to the round window. Further investigations are needed to correlate the qualitative results with the audiological results after "third window vibroplasty" (inserted floating mass transducer without stimulation).

Intra-operative application of confocal endomicroscopy using a rigid endoscope.

OBJECTIVE: To introduce the application of confocal endomicroscopy during microlaryngoscopy, to enable intra-operative evaluation of human laryngeal epithelium. METHODS: A rigid endoscope was connected to the scanner head of a Heidelberg Retina Tomograph II confocal laser scanning system via an adapter. The endoscope was gently placed on the surface of a vocal fold through a laryngoscope during microlaryngoscopy. RESULTS: The application of confocal endomicroscopy using a rigid endoscope enabled technical improvements (i.e. improved image quality, automatic volume scan, and reduced tissue pressure due to the presence of a perforation plate with central hole at the end of the endoscope) which permitted greater sensitivity and improved handling. Confocal endomicroscopy provided good quality, in vivo, en-face images and enabled an assessment of laryngeal epithelium volume. CONCLUSION: This method enables the surgeon to monitor epithelial changes in pre-malignant lesions. The combination of confocal endomicroscopy together with optical coherence tomography (as a complementary technique that provides optical cross-sections) should be further explored in a formal clinicopathological study.

[Mastoid obliteration with a highly porous bone grafting material in combination with cartilage]. / Mastoidhöhlenobliteration mit einem hochporösen Knochenaufbaumaterial (NanoBone®) und Conchaknorpel.

BACKGROUND: An open mastoid cavity might lead to various problems for the patient. Chronic inflammation of the cavity with secretion, changes in the acoustic behavior, vertigo in restricted situations and an impaired self-cleaning function might affect the patient. For surgical treatment reducing of the size of such cavities have been described. Besides autologous materials such as hydroxyapatite or alloplastic substances as tricalcium phosphate have been previously used. A very slow resorption of these materials with rejection has been described. The new ceramic NanoBone® was fabricated in a sol-gel process at 700 °C depositing unsintered hydroxylapatite in a SiO2 structure. This method provides a nano/microstructure of high porosity of the resulting matrix. MATERIAL AND METHODS: 20 patients were reexamined after an average of 2 years and 5 months after obliteration of the open mastoid cavity with NanoBone®. We compared pre- and postoperative findings in terms of otorrhea, frequency of medical consultation, vertigo and otoscopic findings. In 5 patients, in addition, a postoperative CT scan of the temporal bones was used for evaluation of osteoinduction and osteointegration. RESULTS: After obliteration of the open mastoid cavity with NanoBone ® we observed an uneventfully healing. After surgery we achieved a reduction of vertigo, otorrhea and frequency of medical consultations for the single patient. CONCLUSION: The obliteration of an open mastoid cavity with NanoBone ® is a safe alternative method relative to the surgical techniques with autologous materials.

Matrix change of bone grafting substitute after implantation into guinea pig bulla.

BACKGROUND: Many different surgical techniques have been developed to remove open mastoid cavities. In addition to autologous materials, alloplastic substances have been used. A very slow absorption of these materials and extrusion reactions have been reported. We investigated a newly developed, highly porous bone grafting material to eliminate open mastoid cavities, in an animal model. To characterise the transformation process, the early tissue reactions were studied in relation to the matrix transformation of the bone material. MATERIAL AND METHODS: NanoBone (NB), a highly porous bone grafting material based on calcium phosphate and silica, was filled into the open bullae from 20 guinea pigs. The bullae were examined histologically. Energy dispersive X-ray spectroscopy (EDX) was used to investigate the change in the elemental composition at different sampling times. The surface topography of the sections was examined by electron microscopy. RESULTS: After 1 week, periodic acid-Schiffs (PAS) staining demonstrated accumulation of glycogen and proteins, particularly in the border area of the NB particles. After 2 weeks, the particles were evenly coloured after PAS staining. EDX analysis showed a rapid absorption of the silica in the bone grafting material. CONCLUSIONS: NanoBone showed a rapid matrix change after implantation in the bullae of guinea pigs. The absorption of the silica matrix and replacement by PAS-positive substances like glycoproteins and mucopolysaccharides seems to play a decisive role in the degradation processes of NB. This is associated with the good osteoinductive properties of the material.

[Advances in endoscopic diagnosis of dysplasia and carcinoma of the larynx]. / Fortschritte der endoskopischen Diagnostik von Dysplasien und Karzinomen des Larynx.

To improve the preoperative and intraoperative diagnosis of laryngeal cancer and its precursors, various endoscopic imaging techniques have been developed in recent years. These techniques differ markedly in their specific applications and goals. Precisely distinguishing among normal mucosa, dysplasia and invasive carcinoma with these procedures is necessary. Furthermore, the exact identification of tumor margins should be possible. The long-term goal is the development of optical biopsy. Since so far there have only been small studies regarding the evaluation of the presented methods, it is necessary to establish multi-center trials with large sample sizes to accurately estimate the value of these endoscopic imaging techniques.

[Tonsil protrusion in the case of an infraauricular mass. A rare iceberg tumor]. / Tonsillendifferenz bei infraaurikulärer Raumforderung. Ein seltener Eisbergtumor.

We report on a very rare case of iceberg tumor. A giant lipoma arising from the deep lobe of the parotid gland led to an infraauricular mass and tonsil protrusion. After appropriate imaging (ultrasound and MRI) surgical resection was performed. Tonsil protrusions require differential diagnostic evaluation. Apart from the most prevalent parotid gland tumors, like pleomorphic adenoma and cystadenolymphoma, one must consider rare lipomas. Malignancy (e.g. liposarcoma) can only be excluded by histological examination of the whole specimen.

[Optotensometry for measuring the tube function - a feasibility study on a middle ear model]. / Optotensometrie Langzeitmessung der Tubenfunktion - erste Versuche am Mittelohrmodell.

BACKGROUND: The amount of pressure in the middle ear depends mainly on the function of the Eustachian tube. Currently there are no continuous recording techniques measuring Eustachian tube function in clinical context and under physiological conditions over extended periods of time. In this paper we investigate the suitability of an active optic triangulation method on the basis of a projected laser-point-pattern in measuring tympanic membrane movement during pressure variations in a middle ear model. MATERIAL AND METHODS: For projection we used a green semiconductor laser with an output of 1 mW and a diffractive optical element (DOE). As our measured object we used purple latex-foil (Kimberley-Clark (®)), fixed airtight on the cut-off end of a 2 ml syringe-tube. The movement of the foils was measured by an active optic triangulation method. To simulate pathological variations of the tympanic membrane we prepared the latex-foils in specific ways. One foil was perforated and then covered again (simulating tympanic membrane perforation), another one was partly strengthened by sticking a piece of thick, hard paper to it from the inside (simulating calcification). RESULTS: The test-setup, as well as the appliance of pressure-changes worked fine and measurement of foil movement in all the modified foil surfaces was possible. This shows that it is possible to record foil-movement with this system even in tympanic membranes with pathological variations. CONCLUSIONS: In the course of this study we were able to show that it is possible to assess and record foil movement using a system of optic triangulation and to simulate different tympanic membrane pathologies. This could be used both in ENT medicine, as well as in aviation and diving medicine.

Detection of tympanic membrane movement using film patch with integrated strain gauge, assessed by optical coherence tomography: experimental study.

OBJECTIVE: We report an ex vivo and in vivo experimental study of a device designed to measure tympanic membrane movement under normal and pathological conditions, assessed using optical coherence tomography. MATERIALS AND METHODS: We designed two types of flexible, round film patch with integrated strain gauge, to be attached to the tympanic membrane in order to measure tympanic membrane movement. Tympanic membrane attachment was assessed using optical coherence tomography. The devices were tested experimentally using an ex vivo model with varying middle-ear pressure. RESULTS: Optical coherence tomography reliably assessed attachment of the film patch to the tympanic membrane, before and after middle-ear pressure changes. Strain gauge voltage changes were directly proportional to middle-ear pressure recordings, for low pressure changes. Tympanic membrane perforations smaller than 2 mm could be sealed off with the film patch. CONCLUSION: Attachment of the film patch with integrated strain gauge to the tympanic membrane was not ideal. Nevertheless, the strain gauge was able to precisely detect small pressure changes within the middle ear, in this experimental model.

[Tensometry - development of a measurement technique of the tube function in a temporal bone model]. / Tensometrie - Entwicklung eines Langzeitmessverfahrens der Tubenfunktion am Felsenbeinpräparat.

OBJECTIVE: Middle ear pressure depends widely on the function of the eustachian tube. Tube dysfunction is often a trigger for middle ear diseases like chronic otitis media but also for barotrauma. Patients with impaired tubal function should not be exposed to situations with extreme pressure changes. Until today, there is no valid examining method for long-time measuring of the development of middle ear pressure. MATERIAL AND METHODS: The basic idea was to develop a thin flexible film with integrated strain gauges made of platinum and gold, which can be applied directly on the surface of the tympanic membrane. Using these, shifts or distensions of the tympanic membrane in a temporal bone model can be measured and documented. RESULTS: We were able to show that the measuring system was sensitive enough to register pressure variations in the middle ear volume of a temporal bone model. While using a full bridge design of the strain gauge resistors it could be shown that the measuring voltage of the strain gauges were in phase of the pressure measurement curve or according to the positioning in opposite phase. In single resistor mode the measurement were not so positioning depended. Measuring tympanic membrane movement in case of perforation was feasible. CONCLUSIONS: To improve the longtime stability of the strain gauge film the next development step will be to make a new design with Konstantan resistors (CU-Ni-Mn). After a testing period, longtime measurements in clinical studies will follow.

How reliable is visual assessment of the electrically elicited stapedius reflex threshold during cochlear implant surgery, compared with tympanometry?

OBJECTIVES: To assess the reliability of visually assessed thresholds of the electrically elicited stapedius reflex, recorded during cochlear implant surgery, compared with intra-operative tympanometric threshold assessment. Intra-operatively recorded electrically elicited stapedius reflex thresholds vary considerably, and differ from those measured post-operatively by means of impedance changes (i.e. using tympanometry). Thus, any confounding effect of different intra-operative techniques and visual assessment inaccuracies should be excluded. METHODS: Both techniques (i.e. visual observation and tympanometry) were performed intra-operatively in six patients, and threshold values were compared. RESULTS: Recorded electrically elicited stapedius reflex thresholds were very similar for both techniques. Visually assessed thresholds were slightly higher in some cases and lower in others, compared with tympanometric thresholds. DISCUSSION: There was almost no difference between reflex thresholds measured with the two different techniques under the same intra-operative conditions. Therefore, we conclude that differences between intra- and post-operative thresholds are not due to the use of different measuring techniques. The main reason for such differences is probably the influence of intra-operative narcotics on reflex thresholds.

In-vivo signal transmission using an intra-corporal RF transmitter.

In clinical routine, measurements of human physiological parameters are very important. In this paper, a study of RF transmission from the inside to the outside of a biological body is described. In the course of this work, an overview of the state of the art of wireless biotelemetry and the basics of biological tissue attenuation are given. In addition, several prototype transmitters were designed and developed with frequencies ranging from 50 to 700 MHz. With these transmitters a study of an in-vivo transmission was run to measure realistic attenuation values of a living biological subject. In the evaluation phase, a prototype transmitter was placed in the esophagus, near the heart, of a narcotized living pig. This allows demonstrating the transmission out of an animal with human-like tissue properties. The results show a possible transmission at 58, 119, 240, 418 and 672 MHz with acceptable loss.

[Taste disorders. An update]. / Schmeckstörungen. Ein Update.

Clinically, taste disorders are less frequent than smell disorders. Nevertheless, they are very distressing to the concerned patients. Unfortunately, the underlying causes are not always found and a majority of patients are considered idiopathic dysgeusia cases. Besides this taste disorder of unknown origin, medication side effects and surgical injuries are the most frequent origins of dysgeusia. Despite recent, impressive molecular biological and physiological insight into the taste system, few clinical improvements have been achieved. Consequently, curative treatment options remain sparse.

[Thermographic investigations during stapedotomy using a CO2 laser]. / Thermografische Untersuchung während der CO2-Laserstapedotomie.

BACKGROUND: Temporary sensorineural hearing losses after CO(2) assisted stapes surgery have been described in literature. Whether thermal effects are the reason for this side effect is still unclear. The specific aim of this research is to demonstrate the thermal spread during CO(2) laser stapedotomy using a high-speed infrared camera. MATERIAL AND METHODS: Thermal depth effects in physiological saline solutions were examined in cochlea models (glass capillary tube, crystal cuvette and temporal bone preparation). Temperature changes and exchange processes after CO(2) laser application were measured using a high-speed infrared camera. Visualization of gas bubbles triggered by vaporisation underneath the stapes footplate after CO(2) shot was achieved with a high-speed camera. The footplate perforations were performed with a scanner system using a micromanipulator (laser power 20 W, 0.6 mm diameter, continuous wave, duration of 40 ms). RESULTS: Homogenous temperature increases of more than 100°C were measured on the surface of the footplate and 0.25 mm within the capillary tube after single shot CO(2) laser stapedotomy. Gas bubbles may cause isolated temperature increases of up to 65 K. These effects were found in depths of up to 2 mm underneath the stapes footplate. CO(2) shots on the saline solutions with parameter used for initial laser application may lead to temperature increases between 20-65 K in depths of 3-6 mm. CONCLUSIONS: CO(2) applications to an opened inner ear with the same laser parameter used for initial shot on the stapes footplate should be avoided.

[Devitalization of cholesteatoma on human ossicles by hydrostatic high pressure treatment]. / Devitalisierung von Cholestatomanteilen humaner Ossikel durch hydrostatische Hochdrucktechnik.

BACKGROUND: In cholesteatoma surgery the use of autogenous ossicles for restoration of sound conduction is often limited because of ingrowth of matrix epithelia into the ossicular bone. In an attempt to eliminated these epithelial cells we tested extracorporal high-pressure hydrostatic treatment as a new method for devitalizing the bone but maintaining its structure. METHODS: The inpact of different high hydrostatic pressures either on single cell suspensions of fibroblasts and osteoblasts, or on cells in ex-vivo ossicles chain was examined with different methods (quantitative proceedings, live/dead assay). Additional electron microscopic investigations illustrate the influence of high hydrostatic pressure treatment on cell suspensions of osteoblasts. RESULTS: High hydrostatic pressure between 150 MPa and 250 MPa showed no effect to cellular material. A safe elimination of cell growth was found after an application of pressures at or above 400 MPa. The electron microscopic investigations illustrate clearly the destruction of cellular membranes after high hydrostatic pressure treatment. CONCLUSIONS: These findings give hope that after extracorporal high hydrostatic pressure therapy autogenious ossicles might be used for middle ear recontructions even if they had contact with the cholesteatoma matrix or even were infitrated by keratinized squamous cell epithelia.

Vibroplasty involving direct coupling of the floating mass transducer to the oval window niche.

OBJECTIVE: To demonstrate the technique and clinical application of vibroplasty in which the floating mass transducer component of the Vibrant Soundbridge implant is coupled directly to the oval window niche, in patients with a mobile stapes footplate but a malformed or destroyed stapes suprastructure. METHODS: The underlying concept was to create a soft tissue casing for the floating mass transducer, while also firmly connecting the transducer to a small, solid cartilage 'plunger' attached to the stapes footplate. This was realised by removing almost all the cartilage from a larger piece of cartilage-perichondrium, leaving only a tiny cartilage island about half a millimetre in diameter, attached to a much wider 'blanket' of perichondrium. RESULTS: By coupling the floating mass transducer directly to the oval window niche, patients' speech understanding was improved. Post-operative aided thresholds of 30-40 dB HL were achieved by all patients. CONCLUSIONS: In patients with mixed hearing loss combined with a destroyed stapes suprastructure but a mobile stapes footplate, we describe the coupling of the floating mass transducer component of a Vibrant Soundbridge to the stapes footplate, as an alternative to coupling to the round window.

Cutting the chorda tympani: not just a matter of taste.

INTRODUCTION: Chorda tympani injury as a complication of middle-ear surgery has been extensively studied with regard to its effects upon taste. However, the chorda tympani also carries parasympathetic fibres to the salivary glands of the oral cavity. To date, little has been reported about the effect of chorda tympani section upon salivary function. SETTING: Tertiary care centre. MATERIAL AND METHODS: We report a case series of three patients with bilateral chorda tympani lesions. Chorda tympani function was assessed using 'taste strips' and unstimulated sialometry. A careful history of oral symptoms was taken. RESULTS: All patients showed transient or permanent bilateral ageusia of the anterior two-thirds of the tongue, and a decreased resting salivary flow rate. In addition, all patients suffered from transient or persistent, distressing xerostomia. CONCLUSION: Taste disorders may occur after middle-ear surgery but they are mostly transient, even when the chorda tympani nerves are sectioned bilaterally. In contrast, bilateral chorda tympani lesions may lead to severe, persistent and distressing xerostomia. Based on this neglected aspect of chorda tympani function, we emphasise the importance of preserving the chorda tympani whenever possible.