Positioning Accuracy in Otosurgery Measured with Optical Tracking

Objectives

To assess positioning accuracy in otosurgery and to test the impact of the two-handed instrument holding technique and the instrument support technique on surgical precision. To test an otologic training model with optical tracking.

Study Design

In total, 14 ENT surgeons in the same department with different levels of surgical experience performed static and dynamic tasks with otologic microinstruments under simulated otosurgical conditions.

Methods

Tip motion of the microinstrument was registered in three dimensions by optical tracking during 10 different tasks simulating surgical steps such as prosthesis crimping and dissection of the middle ear using formalin-fixed temporal bone. Instrument marker trajectories were compared within groups of experienced and less experienced surgeons performing uncompensated or compensated exercises.

Results

Experienced surgeons have significantly better positioning accuracy than novice ear surgeons in terms of mean displacement values of marker trajectories. The instrument support and the two-handed instrument holding techniques significantly reduce surgeons’ tremor. The laboratory set-up presented in this study provides precise feedback for otosurgeons about their surgical skills and proved to be a useful device for otosurgical training.

Conclusions

Simple tremor compensation techniques may offer trainees the potential to improve their positioning accuracy to the level of more experienced surgeons. Training in an experimental otologic environment with optical tracking may aid acquisition of technical skills in middle ear surgery and potentially shorten the learning curve. Thus, simulated exercises of surgical steps should be integrated into the training of otosurgeons.

Prediction of Parkinson's disease subsequent to severe depression: a ten-year follow-up study

Major depressive disorder (MDD) has been associated with an increased risk of subsequent Parkinson's disease (PD) in case-control and cohort studies. However, depression alone is unlikely to be a useful marker of prodromal PD due to its low specificity. In this longitudinal observational study, we assessed whether the presence of other potential markers of prodromal PD predicts the subsequent development of PD in MDD patients. Of 57 patients with severe MDD but no diagnosis of PD who underwent a structured interview, olfactory and motor investigation and transcranial sonography at baseline, 46 (36 women; mean age 54.9 ± 11.7 years) could be followed for up to 11 (median, 10) years. Three patients (2 women; age 64, 65 and 70 years) developed definite PD after 1, 7, and 9 years, respectively. The combined finding of mild asymmetric motor slowing, idiopathic hyposmia, and substantia nigra hyperechogenicity predicted subsequent PD in all patients who could be followed for longer than 1 year. Out of the whole study cohort, only the subjects with subsequent PD presented with the triad of asymmetric motor slowing, idiopathic hyposmia, and substantia nigra hyperechogenicity in combination with at least two out of four reportable risk factors (family history of PD, current non-smoker, non-coffee drinker, constipation) at baseline investigation. Post-hoc analysis revealed that additional rating of eye and eye-lid motor abnormalities might further improve the prediction of PD in larger cohorts. Findings of this pilot-study suggest that MDD patients at risk of subsequent PD can be identified using an inexpensive non-invasive diagnostic battery.

Comparative Study between the Surgeon's Intraoperative Evaluation and Histopathology for Diagnosis of Laryngeal Lesions

Objective. To compare the surgeon's evaluation and histopathology for diagnosis of laryngeal lesions. Material. A clinical survey was distributed to laryngeal surgeons, ENT clinicians, and students in 2013 at the Department of Otorhinolaryngology in Rostock. Participants were asked to anonymously identify laryngeal pathologies and to assess the severity of the lesion starting from hyperplasia and inflammation over moderate dysplasia to early laryngeal cancer. Images of similar clinical laryngeal lesions were demonstrated in a multiple-choice modus to assess the surgeon's intraoperative evaluation. The questionnaires were digitally processed and evaluated. The results were correlated with histopathology and compared between experienced laryngeal surgeons, clinicians inexperienced in laryngeal surgery, and medical students from the Medical Faculty of the University of Rostock. Results. Sensitivity and specificity varied among the various groups, being highest in experienced laryngeal surgeons. In this group, sensitivity, specificity, positive and negative predictive value, and accuracy were 85%, 56%, 44%, 90%, and 65%, respectively. In 4% and 31%, laryngeal disease was underdiagnosed and overdiagnosed, respectively. In this group, Kappa statistics resulted in Kappa 0.32 (P < 0.001). Conclusion. This clinical survey clearly demonstrates that conformity between histopathology and evaluation of the laryngeal lesion depends on the surgeon's experience.

Conservative management of post-intubation tracheal tears-report of three cases

Iatrogenic tracheal rupture is a rare complication after intubation. We present three patients with tracheal tears. In all of these patients, a common finding was a lesion of the posterior tracheal wall with postoperative subcutaneous and emphysema as the first clinical sign of the rupture. Diagnosis and follow-up were based on clinical and endoscopic findings and chest computed tomography (CT) scans. In our cases with progressive subcutaneous and mediastinal emphysema or dyspnea, we performed a tracheotomy and bypassed the lesion with a tracheostomy tube to avoid an increase in air leakage into the mediastinum. Under broad-spectrum antibiotic therapy, no mediastinitis occurred and all patients survived without sequelae. Closure of tracheostomy was scheduled for 1-2 months after tracheal injury. Analysis of surgical and anesthesiological procedures revealed no abnormalities and the accumulation of tracheal injuries was considered as accidental. We found that in clinically stable patients with spontaneous breathing and with no mediastinitis, a conservative management of tracheal tears is a safe procedure.

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]

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).

Would an endosteal CI-electrode make sense? Comparison of the auditory nerve excitability from different stimulation sites using ESRT measurements and mathematical models

Regarding potential endosteal cochlear implant electrodes, the primary goal of this paper is to compare different intra- and extra-cochlear stimulation sites in terms of current strengths needed for stimulating the auditory nerve. Our study was performed during routine cochlear implantation using needle electrodes for electric stimulation and by visually recording electrically elicited stapedius reflexes (ESRT) as a measure for the stimulus transfer. Of course this rather simple setup only allows rough estimations, which, however, may provide further arguments whether or not to proceed with the concept of an endosteal electrode. In addition, a mathematical model is being developed. In a pilot study, intra-operative electric stimuli were applied via a needle electrode commonly used for the promontory stimulation test. Thus, stapedius reflex thresholds (ESRTs), electrically elicited via the needle from different points inside and outside the cochlea served as indicators for the suitability of different electrode positions towards the modiolus. Tests were performed on 11 CI-recipients. In addition, the extension of electrical fields from different stimulation sites is simulated in a mathematical cochlea model. In most patients ESRT measurements could be performed and evaluated. Thus an "endosteal" stimulation seems possible, although the current intensities must be higher than at intraluminal stimulation sites. Moreover, our model calculations confirm that the extension of electric fields is less favourable with increasing distance from the electrode to the ganglion nerve cells. In terms of hearing, the concept of an endosteal electrode should only be promoted, if its superiority for hearing preservation can be proven, e.g. in animal experiments. However, for other indications like the electric suppression of tinnitus, further research seems advisable.

LEVELS OF EVIDENCE

N/A.

[Mastoid obliteration with a highly porous bone grafting material in combination with cartilage]

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.

[Advances in endoscopic diagnosis of dysplasia and carcinoma of the 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.

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.

Taste function after stapes surgery

OBJECTIVE

A manipulation of chorda tympani nerve (CTN) is frequently necessary during the surgical therapy of stapedial ankylosis. The aim of this study was to re-assess the taste function before and after stapes surgery in patients with unilateral stapes ankylosis.

METHODS

Eighteen patients (14 female and 4 male) with unilateral stapedial ankylosis were included. Taste and olfactory function were measured preoperatively, 3 days and 3 months after surgery by questionnaire, chemical taste test, electrogustometry, and Sniffin'Sticks. The patients who reported deterioration in taste and revealed pathological taste test results were re-investigated 8-12 months after surgery. Postoperatively 11 patients were treated intravenously for 3 days for inner ear protection with 1g of cortisone. The gustatory and olfactory results were compared with age and sex specific normative data.

RESULTS

A significant transient decrease of gustatory measurement values was found on the ipsilateral two thirds of the anterior tongue. 12 out of 17 patients whose CTN was slightly manipulated during stapes surgery reported tongue sensations, such as numbness or gustatory blindness of the ipsilateral tongue side. The measures of chemical taste test significantly decrease in lateralized taste test on the ipsilateral side and in whole mouth testing. There was no significant increase of the EGM measures at the ipslateral tongue. In 11 of 12 patients with symptoms, complaints recovered within one year after surgery completely. The factor "cortisone" did not have a significant effect on the taste test results after surgery.

CONCLUSION

In conclusion, even after minor CTN manipulation the rate of postoperative taste disorders or tongue symptoms after stapes surgery is high. The symptoms appear to be transient. Therefore CTN should be preserved in stapes surgery after mild trauma of the CTN. Transient taste alteration should be mentioned prior to stapes surgery.

Effect of the stapedotomy technique on early post-operative hearing results--Preliminary results

OBJECTIVE

To compare three stapedotomy modalities used to fenestrate the stapes footplate in patients with primary otosclerosis.

MATERIALS

The non-randomized and unblinded one-center study included 48 patients with primary otosclerosis who underwent stapes surgery between May 2008 and April 2009. The patients were divided into three groups (single shot and two-shot CO(2) laser stapedotomy, perforator) depending on the modality used for stapedotomy. Bone conduction (BC) and air conduction (AC) thresholds, air-bone gap (ABG), and the difference between mean pre-operative and 2- to 3-week post-operative BC thresholds were analyzed.

RESULTS

The temporary BC deterioration was most pronounced at 6 and 8kHz after 2-shot laser stapedotomy. A significant drop in AC or BC was not found in any of our 48 patients. Age, high-dose cortisone therapy, and 'preoperative hearing' did not influence the post-operative hearing results.

CONCLUSION

Even though the number of patients presented here was small and statistical analysis was limited, the study showed a trend toward worse BC thresholds at 6 and 8kHz after a second shot CO(2) application. Whenever possible, treatment should avoid a second laser shot on the already opened inner ear with the laser parameters used for the initial shot.

[Optical coherence tomography in otolaryngology]

Optical coherence tomography is an imaging technique based on coherence interferometry. It is used in many medical fields due to its non-invasive imaging capabilities with micrometer resolution. The aim of the authors was to review the applicability of the optical coherence tomography in otolaryngology. Literature data and their own studies show that optical coherence tomography is a reliable method for identifying and targeted biopsy of inflammated, pre-malignant or cancer tissue in human laryngeal and pharyngeal mucosa. Another emerging field for optical coherence tomography is diagnosis of middle ear diseases, especially stapes ankylosis and cholesteatoma.

[Tonsil protrusion in the case of an infraauricular mass. A rare iceberg tumor]

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.

Changes in taste bud volume during taste disturbance

On-line mapping and serial volume measurements of taste buds with confocal laser scanning microscopy provide information on the peripheral gustatory organ over time. We report the volumetric measurements of four selected fungiform papillae over 8 weeks in a 62-year-old man with taste disturbance, which was more apparent on the right than on the left side. In the two papillae on the right side, no taste buds were detected within the fungiform papillae in the sixth and eighth week. During sixth and eighth week, there was no response to the highest presented stimuli in electrogustometry (1 mA) on the right-sided tongue tip nor at the tongue edge. The morphology (shape, diameter) of the fungiform papillae on both sides remained unchanged. Comparison of the time course of the volume changes revealed differences corresponding to gustatory sensitivity. These findings suggest that the time course of volume changes indicated taste disturbance in our patient, rather than morphological changes in the fungiform papillae.

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.

Optical coherence tomography allows for the reliable identification of laryngeal epithelial dysplasia and for precise biopsy: a clinicopathological study of 61 patients undergoing microlaryngoscopy

OBJECTIVES/HYPOTHESIS

A newly developed microscope-based spectral-domain optical coherence tomography (SD-OCT) device and an endoscope-based time-domain OCT (TD-OCT) were used to assess the inter-rater reliability, sensitivity, specificity, and accuracy of benign and dysplastic laryngeal epithelial lesions.

STUDY DESIGN

Prospective study.

METHODS

OCT during microlaryngoscopy was done on 35 patients with an endoscope-based TD-OCT, and on 26 patients by an SD-OCT system integrated into an operating microscope. Biopsies were taken from microscopically suspicious lesions allowing comparative study of OCT images and histology.

RESULTS

Thickness of the epithelium was seen to be the main criterion for degree of dysplasia. The inter-rater reliability for two observers was found to be kappa = 0.74 (P <.001) for OCT. OCT provided test outcomes for differentiation between benign laryngeal lesions and dysplasia/CIS with sensitivity of 88%, specificity of 89%, PPV of 85%, NPV of 91%, and predictive accuracy of 88%. However, because of the limited penetration depth of the laser light primarily in hyperkeratotic lesions (thickness above 1.5 mm), the basal cell layer was no longer visible, precluding reliable assessment of such lesions.

CONCLUSIONS

OCT allows for a fairly accurate assessment of benign and dysplastic laryngeal epithelial lesion and greatly facilitates the taking of precise biopsies. Laryngoscope, 2010.

Normative data for a solution-based taste test

The aim of our study was to study gustatory function in a large portion of the general population using liquid tastants, extending previous research. Further, we investigated the test-retest reliability of the test used. Data from 944 healthy subjects were used (498 women and 446 men, mean age 45 years; age range 5-90 years). For lateralized assessment of gustatory function, liquid taste solutions were used with different concentrations of each tastant (sweet 0.03, 0.1, 0.4, 2 g/mL sucrose solution; sour 0.01, 0.05, 0.1, 0.15 mL citric acid; salty 0.025, 0.075, 0.15, 0.36 mL sodium chloride solution; bitter 0.0002, 0.0005, 0.001, 0.01 mL quinine hydrochloride). A drop (approximately 20 µL) of liquid tastant was applied on the right side or on the left side of the anterior/posterior third of the extended tongue. The taste test had a good test-retest reliability r (304) = 0.78 (P < 0.001) for the total score and r (304) = 0.77 (P < 0.001) for the right-sided measures and r (304) = 0.75 (P < 0.001) for the left-sided measures, respectively. Gustatory sensitivity was found to decrease with age; women were more sensitive to gustatory stimuli than men. Irrespective of the sex-related differences, the total score at the 10th percentile was 28 in subjects younger than 15 years, 26.1 for ages from 16 to 35 years, 25 for ages from 36 to 55 years, and 24 for subjects older than 56 years of age. In conclusion, this test is recommended for clinical assessment of the ability to taste. The test provides reliable data, which is easy to handle, inexpensive, timesaving and can be self-made.

[Devitalization of cholesteatoma on human ossicles by hydrostatic high pressure treatment]

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.

Rigid confocal endoscopy for in vivo imaging of experimental oral squamous intra-epithelial lesions

BACKGROUND

A rigid confocal endoscope has been developed to assess the oral squamous epithelium of mice and to determine sensitivity, specificity, and accuracy of this new technology.

METHODS

This endoscope is connected to the commercially available Heidelberg Retina Tomograph (HRT). HRT is a device with a 670-nm diode laser designed to acquire topographical measurements of the optic nerve head. Real-time rigid confocal endoscopy is demonstrated by imaging the epithelial lesions of a mice model. Six-week-old male C57Bl/6 mice were randomly divided into a non-treated group (n = 10) and into a 4-nitroquinoline 1-oxide (4-NQO)-treated group (n = 50). In the 4-NQO-treated group, the mice obtained 4-nitroquinoline 1-oxide in the drinking water (100 microg/ml) to induce tumourigenesis in the mouse tongue. The 4-NQO-solution was diluted in the drinking water for mice. After an 8-16-week carcinogen treatment with 4-NQO (ad libitum), mouse tongues were dissected within 3 h after CO(2) overdose. After confocal microscopy of all lesions of the tongue, conventional histopathological investigation was performed.

RESULTS

The inter-rater reliability for the two observers of the confocal microscopic findings was found to be Kappa = 0.59 (P < 0.001). The penetration depth varied in the healthy tissue of the underside of the tongue throughout this study and was measured between 104 and 240 microm. In keratotic lesions, the penetration depths were diminished and varied between 80 and 140 microm. Strong keratinization inhibits the evaluation of the epithelium. For differentiation between low-grade and high-grade squamous intra-epithelial lesions, a sensitivity and specificity of 73% and 88% was reached.

CONCLUSIONS

The animal experiment with this non-invasive new technology indicates that this imaging technology facilitates the detection of pre-cancerous lesions of the underside of the oropharynx. Human studies on oropharyngeal and laryngeal lesions are needed to prove the applicability of this method in the field of otorhinolaryngology.

Change of the human taste bud volume over time

OBJECTIVE

The specific aim of this study is to measure the taste volume in healthy human subjects over a 2.5-month period and to demonstrate morphological changes of the peripheral taste organs.

MATERIAL AND METHODS

Eighteen human taste buds in four fungiform papillae (fPap) were examined over a 10-week period. The fungiform papillae investigated were selected based on the form of the papillae or the arrangement of surface taste pores. Measurements were performed over 10 consecutive weeks, with five scans in a day once a week. The following parameters were measured: height and diameter of the taste bud, diameter of the fungiform papilla and diameter of the taste pore.

RESULTS

The findings of this exploratory study indicated that (1) taste bud volumes changed over a 10-week period, (2) the interval between two volume maxima within the 10-week period was 3-5 weeks, and (3) the diameter of the fPap did not correlate with the volume of a single taste bud or with the volume of all taste buds in the fPap within the 10-week period.

CONCLUSIONS

This exploratory in vivo study revealed changes in taste bud volumes in healthy humans with age-related gustatory sensitivity. These findings need to be considered when studying the effect of denervation of fungiform papillae in vivo using confocal microscopy.

Pressure changes in the human middle ear without opening the eustachian tube

CONCLUSION

By means of a direct, though non-invasive experiment on healthy humans we could demonstrate that middle ear (ME) pressure decreases when the eustachian tube (ET) does not open. Thus with a very simple method the basic theory of continuous gas loss from the ME into the circulation and the replenishment of the loss through the ET could be validated.

OBJECTIVES

To record changes in ME pressure over a period of time in normal human ears, while the ET is kept closed.

SUBJECTS AND METHODS

On-line tympanometry was carried out in three subjects, who refrained from swallowing for 20-120 min.

RESULTS

During the time when the ET was kept closed by refraining from swallowing, tympanometric monotonous pressure decrease was recorded. Once the tested subject could not refrain from swallowing any longer and swallowed again, ME pressure equalized immediately.

Tympanometric experiments on retracted ear drums--does tympanometry reflect the true middle ear pressure?

CONCLUSIONS

Tympanometry in ears with retracted or partially atelectatic tympanic membranes does not reflect the true middle ear (ME) pressure. The position of the tympanogram peak depends on the size of a retraction pocket and the remaining ME gas volume. Thus tympanometry in such cases cannot be used for measurements of ME pressure.

OBJECTIVE

To prove the hypothesis that tympanometry in ears with retraction pockets or atelectasis does not measure ME pressure correctly.

MATERIALS AND METHODS

Tympanometry was performed in a simplified artificial ME model, in which different 'tympanic membranes' with pockets could be integrated.

RESULTS

We found a shift of the tympanogram peaks, either towards negative or positive pressures, depending on the position of the pocket: in case of an 'inward' direction (towards the ME like a retraction pocket) the peak was in the negative pressure range, in case of an 'outward' direction (bulging into the ear canal) the shift was towards positive pressures. The shift increased with decreasing volume behind the tympanic membrane. The effect cannot be simply be explained by hysteresis but by the air 'cushion' that is 'trapped' behind the membrane, limiting its excursions during the tympanometric sweep.

Monitoring residual hearing during cochlear implantation by intra-operative brainstem audiometry

OBJECTIVE

Aim of this paper is to prove the applicability of intra-operative recordings of auditory brainstem responses during cochlear implantation.

METHODS

The clinical practicability of intra-operative monitoring of hearing thresholds (Notched-Noise BERA, Amplitude Modulation Following Response [AMFR]) is presented in the respective case. The recordings were performed prior to the cochlear implantation and were compared with those obtained during and after cochlear implantation.

RESULTS

It is demonstrated that the patient's cochlear function can be monitored; residual hearing is available after surgery.

CONCLUSION

The possibility of monitoring of hearing thresholds may add some security to the concept of electric-acoustic stimulation.

Changes of oral trigeminal sensitivity in patients after middle ear surgery

OBJECTIVES

The specific aim of this study was to re-investigate the effect of chorda tympani damage on both trigeminal sensitivity and taste ability.

STUDY DESIGN

Prospective study.

METHODS

Capsaicin-impregnated filter paper strips (5 concentrations, 0.0001-1%) were used to measure trigeminal thresholds. The strips were placed on the anterior tongue for 10 seconds. Thresholds were estimated in two ways: 1) thresholds related to sensory perception and 2) intensity-related thresholds. The test was applied to 29 patients who underwent middle ear surgery (mean age, 49 yr; 16 females, 13 males). Results were compared with those of 63 healthy subjects (mean age, 40 yr; 36 females, 29 males). In addition to trigeminal thresholds, measures of gustatory function were also obtained using both the validated "taste strips" test kit and electrogustometry.

RESULTS

For lateralized testing with capsaicin, significant differences were found between preoperative and postoperative thresholds and between the operated and nonoperated side, with thresholds being higher postoperatively on the operated side. The sensation-related thresholds from the operated tongue side exhibited a correlation with the corresponding postoperative electrogustometric thresholds. A higher degree of chorda manipulation was associated with higher postoperative capsaicin thresholds at the operated tongue side.

CONCLUSION

Pain-related sensitivity of the tongue decreases after middle ear surgery, indicating that chorda tympani function also influences intraoral trigeminal sensitivity.

Optical coherence tomography as an orientation guide in cochlear implant surgery?

CONCLUSION

With optical coherence tomography (OCT) it is basically possible to reveal parts of the cochlear morphology without opening its enveloping membranes. Thus, it may serve as a helpful guide for the surgeon to localize the scala tympani precisely before opening the fluid-filled inner ear to insert the electrode array.

OBJECTIVE

To improve anatomical orientation in cochlear implant surgery before definitively opening the fluid-filled inner ear. The question was whether a new imaging technique, OCT, might provide information about the site of the underlying inner ear structures (scala tympani, scala vestibuli) and could, consequently, guide the surgeon towards the scala tympani.

MATERIALS AND METHODS

In a preliminary study, OCT was carried out on human temporal bone preparations, in which a cochleostomy ('fenestration') was performed leaving the endosteum and the fluid-filled inner ear intact. OCT was applied via a prototype of a specially equipped operating microscope. The mode of OCT used in this context was spectral-domain (SD)-OCT.

RESULTS

On scans, which can be read analogous to B-mode sonography, OCT provides information about structures on the inner surface of the partly exposed but still intact membranous cochlear lining - such as scala tympani or scala vestibuli.

Temporal bone investigations on landmarks for conventional or endosteal insertion of cochlear electrodes

CONCLUSION

Our anatomical findings place special emphasis on the requirement to follow an infero-anterior approach to the round window, to expose the scala tympani safely for 'normal' cochlear implantation. It is also known how easily the basilar membrane may be accidentally damaged, despite exercising considerable caution in the approach used. With regard to an 'endosteal electrode' it can be stated that there are no really specific indicators to locate the spiral ligament, or each of the scalae, on the lateral aspect of the tissue layer encasing the cochlea. For the concept of an endosteal electrode, however, the soft tissue layer of the lateral aspect of the cochlea is considered to be sufficiently thick to serve as a physical barrier between the electrode and the inner ear fluid.

OBJECTIVES

To re-evaluate surgical techniques of gaining access to the scala tympani for cochlear implantation (cochleostomy, 'fenestration'). There are two reasons for this study. First, recent publications show that in a significant number of patients the electrode array was unintentionally inserted into the 'wrong' scala (sc. vestibuli). Second, dealing with an alternative concept proposed by Lehnhardt for patients with residual hearing ('endosteal electrode'), the anatomical site of the spiral ligament should be known. In a study on human temporal bones the topography of the middle and inner ear is revised with regard to the presence of anatomical or surgical landmarks that may guide the surgeon.

MATERIALS AND METHODS

Anatomical examinations were performed on 10 temporal bones (5 fresh specimens and 5 fixed in formalin), in which the bone of the promontory was carefully milled. The consistency of identification and the relative location of specific surgical indicators or landmarks such as 'blue lines' and 'gray lines' were evaluated for 10 temporal bones. Furthermore, the projection of the lateral attachment of the basilar membrane on the promontory was determined with regard to round window anatomy.

RESULTS

In all cases, a major blue line indicated the lateral aspect of the basal cochlear turn while milling the promontorial bone. In a limited number of cases (20%), an additional gray line potentially indicated the spiral ligament before the last shell of bone was removed. In 80% of the cases it was possible to remove the bony layer and leave the endosteum intact as a precondition for a potential endosteal electrode insertion. In addition, through the examination of these models, the relative anatomical location of structures, such as the scala vestibuli, scala tympani, spiral ligament, and basilar membrane, is reviewed.

Konfokalmikroskopische Untersuchungen des Kehlkopfepithels

BACKGROUND

To evaluate mucosal changes of the true vocal cord, e. g. leukoplakia, microlaryngoscopy is needed to obtain tissue for histopathologic investigation. But there is a discrepancy between the amount of representative tissue necessary for pathology and the postoperative voice function. Thus, a diagnostic procedure that enables the surgeon to differentiate inflammation from dysplasia and carcinoma in situ intra-operatively is urgently needed. We are now reporting on our results using laser scanning microscopy to visualize larynx epithelia.

METHODS

The laser scanning microscope used in this ex vivo study is a combination of the Heidelberg Retina Tomograph HRTII and the Rostock Cornea Module. A 63 x water immersion objective lens was used for imaging.

PATIENTS

Seven larynx preparations of patients (age 54 to 62 years) with a T4 larynx carcinoma who underwent laryngectomy between 2003 and 2006 were examined.

RESULTS

Areas of epithelia of the true vocal cord of macroscopically normal appearance supplied images of healthy, but also inflamed laryngeal epithelia. The corresponding histopathologic sections prepared horizontally confirmed the regularity and homogeneity of the mucosa. The different layers of the lamina propria can be separated. In contrast to healthy and inflamed laryngeal mucosa, dysplasia, precancerous lesions and carcinoma-atypical cells were visible. In the latter entity a loss of cellular junctions characterized by lack of visualization of the cell membrane was apparent.

CONCLUSIONS

LSM supplies information of healthy, inflamed, but also pre-malignant and malignant mucosa changes of the larynx. The pilot study shows that both hyperkeratosis and extensive hyperplasia confine the visualization of the basement cell layer. Research projects have been initiated with the objective to develop a rigid endoscope with integrated LSM technology.

Noise Exposure of the Inner Ear During Drilling a Cochleostomy for Cochlear Implantation

OBJECTIVES

Inserting an electrode array into the cochlea may cause inner ear trauma, which has to be minimized, particularly in cochlear implant patients with substantial residual hearing. Another potential inner ear trauma has, to a large extent, been neglected so far: the acoustic trauma that can occur during cochleostomy using different techniques. In this study, the noise exposure of the inner ear during the drilling procedure was re-evaluated. In experiments on temporal bones, quantitative measurements of sound pressure level (SPL) were carried out while a cochleostomy for cochlear implantation was drilled.

STUDY DESIGN

Experimental study.

MATERIALS AND METHODS

Acoustic measurements during different drilling procedures were carried out on four human temporal bone preparations equipped with microphones attached to the round window. Special calibrations were carried out, which allowed determination of SPLs affecting the cochlea during the drilling procedure.

RESULTS

The highest SPLs measured on the cochlea were recorded when a still-intact endosteal membrane was touched by the burr. The SPL exceeded 130 dB and reached a level almost comparable with the situation when the ossicular chain is touched by a running burr.

CONCLUSIONS

In the drilling procedure for a cochleostomy, the inner ear may be affected by very high SPLs, particularly if the endosteal membrane is left intact and comes into contact with the running burr. Of course, the resulting SPLs depend on the drilling speed and the size and characteristics of the burr (larger burrs cause higher SPLs); however, we are of the opinion that the cochlear function is at risk, anyway, if special precaution is not exercised. Even when working with reduced drilling speed, the surgeon should be aware of the high risk in the form of an acoustic trauma, which may endanger residual hearing. Recommendations in terms of "soft surgery" are given in the paper (e.g., the use of microhooks instead of a drill to remove the very last shell of bone covering the cochlea).

Assessment of oral trigeminal sensitivity in humans

The aim of this prospective study was to establish a clinical test for the assessment of oral trigeminal sensitivity. Capsaicin-impregnated filter paper strips (five concentrations: 0.0001-1%) were used to measure trigeminal thresholds. The strips were placed on the anterior tongue for 10 s. Subjects were asked to report the onset of any sensory perception, quality and duration of sensory perception. Thresholds were estimated in two ways: (1) threshold (THR1) related to sensory perception and (2) intensity related threshold (THR2). The test was applied to 63 healthy subjects (mean age 40 years; 34 women, 29 men). For whole-mouth testing with capsaicin, a small but significant correlation was found between THR1 and THR2 (r (63) = 0.41). Coefficients of correlation between test and re-test were r (30) = 0.60 for THR1 and r (30) = 0.78 THR2. Neither THR1 nor THR2 indicated either side or sex-related differences. Age-related differences were only found in THR2 scores, which were lower in young subjects (<40 years). Reliable assessment of intraoral trigeminal sensitivity appears to be possible using the presently described technique.