Assessment of olfactory function and androstenone odor thresholds in humans with or without functional occlusion of the vomeronasal duct

To obtain information on the possible role of the vomeronasal duct (VND) in odor perception and human pheromone detection, the present study investigated different aspects of olfactory function, including thresholds for androstenone in adults with or without detectable VNDs. The study also examined correlations between detection thresholds of androstenone odor and general olfactory function. Subjects' olfaction was assessed with tests for odor identification, odor discrimination, and phenyl ethyl alcohol odor threshold. Measurements were performed on 1 side only, with and without covering the VND. Subjects with or without detectable VNDs did not differ in olfactory sensitivity or androstenone odor thresholds. A small but significant correlation was found between detection thresholds of androstenone and general olfactory function. Finally, covering of the VND did not affect olfactory function or androstenone sensitivity. Results suggest that the human VND does not play a major role in sensitivity toward odorants or the perception of androstenone.

Clinical presentation of qualitative olfactory dysfunction

Many patients with olfactory dysfunction not only experience quantitative reduction of olfactory function, but also suffer from distorted olfactory sensations. This qualitative dysfunction is referred to as parosmia (also called "troposmia") or phantosmia, with the major difference that distorted olfactory sensations are experienced in the presence or absence of an odor, respectively. Our clinical observations corroborate the literature in terms of a general underestimation of the incidence of olfactory distortions. Based on selected cases we try to show that olfactory distortions exhibit a large variance in their clinical appearance. Further, emphasis is placed on the fact that only a detailed and directed history of the patient can provide cues to the correct diagnosis.

Biomechanics of stapesplasty: a review

OBJECTIVE

The replacement of an otosclerotic fixed stapes by a prosthesis significantly modifies the function of the normal ossicular chain. Because the ear works as a pressure receptor, a piston prosthesis will both modify the sound pressure transmission and respond to the ambient air pressure changes in a different way than the normal stapes. Both aspects, the acoustic transmission and the displacements of the prosthesis with variations of atmospheric pressures, are reviewed.

CONCLUSION

The diameter of a piston should not be smaller than 0.4 mm and it should be inserted into a significantly larger perforation of the footplate. A low mass is advantageous for transmission of higher frequencies. Firm attachment at the processus lenticularis is necessary for effective energy transmission. This is of paramount importance in a malleovestibulopexy because of the oblique position of the piston. A piston can be displaced up to 0.5 mm in the vestibule at ambient air pressure changes, as it is not attached to the annular ligament. These large movements explain why a short piston can be lifted out of the footplate fenestration (i.e., after sneezing) and why a piston with excessive length can impale the structures of the membranous labyrinth, causing vertigo (i.e., in a retraction of the tympanic membrane). However, flying or diving should be allowed generally, provided that a test with tympanometry, applying variable pressures of +/- 400 mm H(2)O, is tolerated without evoking vertigo.

Effects of olfactory function, age, and gender on trigeminally mediated sensations: a study based on the lateralization of chemosensory stimuli

The present investigation aimed to compare trigeminal nasal function of anosmic and hyposmic patients to healthy controls. Further, we aimed to study effects of age and gender on trigeminally mediated sensations following intranasal chemosensory stimulation. Participants were 35 patients with olfactory dysfunction (n=13: functional anosmia; n=22: hyposmia; age 28-69 years, mean age 56 years). Their results were compared with 17 normosmic subjects (28-82 years, mean 52 years). To analyze effects of age and gender in healthy subjects, an additional 24 healthy subjects were included (19-27 years; mean 24 years). Olfactory function was assessed using the 'Sniffin' Sticks' test kit (butanol odor threshold, odor discrimination, odor identification). The subjects' ability to lateralize odors was investigated for benzaldehyde and eucalyptol. Patients with olfactory dysfunction had lower scores in the lateralization task than controls (P<0.001) indicating decreased trigeminal sensitivity. Among anosmic patients scores were not different in relation to different causes of olfactory dysfunction (P>0.29). There was a weak, but significant, correlation between localization of eucalyptol and duration of olfactory dysfunction (P=0.017). When investigating normosmic subjects only, no gender-related difference was apparent for lateralization scores. However, older subjects had lower scores than younger ones (P<0.01). Results of partial correlational analyses controlling for age suggested a relation between the trigeminal and the olfactory systems. In conclusion, results of the present study indicate that patients with olfactory dysfunction have lower trigeminal sensitivity compared with normosmic controls. This seems to be independent of the cause of olfactory loss. The deficit appears to improve with duration of the olfactory dysfunction, possibly indicating adaptive mechanisms. Further, the data suggest an age-related decrease of intranasal trigeminal sensitivity in healthy subjects. Analyses additionally indicate a correlation between olfactory and trigeminal sensitivity.

[Modeling light distribution in nasal tissue structures]

There are different applications in the field of optical diagnostics in which the theories explaining the light transport in tissue do not lead to simple solutions for complicate geometric conditions. In these cases the Monte Carlo method provides a powerful tool to solve this problem statistically. In order to simulate the light transport in the nasal region a model was created which includes the structure depending on the swelling of the mucous membrane as well as the Monte Carlo model. Using this model it is possible to evaluate the measured values qualitatively. However, due to the long distance between light source and detector the statistical error becomes a major problem for reliable statements.

Acoustic properties of different cartilage reconstruction techniques of the tympanic membrane

OBJECTIVES/HYPOTHESIS

The use of cartilage in reconstruction of the tympanic membrane has been established especially in cases such as tubal dysfunction and adhesive processes. Cartilage offers the advantage of higher mechanical stability compared with membranous transplants but may alter the acoustic transfer characteristics of the graft. Apart from material properties, it can be assumed that, also, the microsurgical reconstruction technique might influence the sound transmission properties of the reconstructed tympanic membrane. The purpose of the study was to investigate the acoustic transfer characteristics of different cartilage transplants being typically used in different reconstruction techniques of the tympanic membrane.

METHODS

Cartilage plates of different thicknesses (1.0, 0.7, 0.5, and 0.3 mm), cartilage palisades, and cartilage island transplants of varying size were investigated by means of an ear canal-tympanic membrane model. In contrast to former single-point measurements, sound-induced vibrational amplitudes of the entire transplant were measured by scanning laser Doppler vibrometry (measuring points, n = 133) (PSV-200, Polytec, Waldbronn, Germany). Frequency response functions (displacement vs. sound pressure) of all measured points were determined in the frequency range of 200 Hz to 4 kHz for the different transplants.

RESULTS

Cutting thick cartilage transplants into thin plates or palisades decreased the first resonance frequency and increased its amplitude, reflecting improved sound transmission properties of the transplant. From an acoustical point of view, the 0.5-mm cartilage plate seems preferable compared with the palisade technique. Cartilage island techniques showed vibration characteristics superior to plate or palisade techniques.

CONCLUSIONS

Apart from material characteristics, the sound transmission properties of the reconstructed tympanic membrane are strongly influenced by the reconstruction technique. The choice of the surgical technique should consider requirements based on mechanical stability and acoustic transfer characteristics of the transplant.

Effects of antihistamines on leukotriene and cytokine release from dispersed nasal polyp cells

In this study the effects of antihistamines on the release of eicosanoids and the pro-inflammatory cytokine tumor necrosis factor alpha (TNF alpha) were compared. Enzymatically dispersed cells from human nasal polyps served as an in vitro model of chronic respiratory mucosal inflammation. Nasal polyp cells (2 x 10(5)/ml) were sensitized with human IgE pre-incubated azelastine (CAS 58581-89-8), terfenadine (CAS 50679-08-8), levocabastine (CAS 79516-68-0) or cetirizine (CAS 83881-51-0), and stimulated with anti-human immunoglobulin E (IgE). Thromboxane B2 (TBX2) and leukotriene C4 (LTC4) were measured by radioimmunoassay (RIA), TNF alpha by enzyme-linked immunosorbent assay (ELISA). Data represent mean values of % inhibition estimated from the untreated positive control or mean IC50 (n = 5). Azelastine and terfenadine inhibited TNF alpha release with IC50 values of 6.2 mumol/l and 4.3 mumol/l, respectively. Terfenadine reduced TXB2 release by 37 +/- 15%, and LTC4 release was decreased by azelastine and terfenadine very potently by 86% and 100%, respectively. Azelastine shows anti-inflammatory properties in therapeutically relevant concentrations as assessed by its ability to reduce TNF alpha release as well as its ability to inhibit LTC4 production in allergically stimulated human nasal polyp cells.

MR evaluation in patients with isolated anosmia since birth or early childhood

BACKGROUND AND PURPOSE

Anosmias with chromosomal disorders has been well investigated. However, isolated anosmia (IA) has received less attention, although it occurs more frequently. We compared frontobasal structures in patients with IA since birth or early childhood with those in control subjects.

METHODS

Imaging findings obtained in 16 patients with IA were compared with those obtained in eight control subjects. Imaging was performed with a standard quadrature head coil at 1.5 T. T1-weighted spin-echo (coronal plane perpendicular to frontal skull base; section thickness, 3 mm; pixels, 0.43 x 0.39 mm) and sagittal T1-weighted magnetization-prepared rapid gradient-echo (voxels, 1.0 x 1.0 x 1.0 mm) sequences were performed. We assessed the length and depth of the olfactory sulcus, olfactory bulb volume, and olfactory sulcus depth in the plane of the posterior tangent through the eyeballs (PPTE).

RESULTS

Five patients with IA had bilateral hypoplastic olfactory bulbs. Three patients with IA had hypoplastic olfactory bulbs on the right and aplastic olfactory bulbs on the left. Eight patients with IA had bilaterally aplastic olfactory bulbs. The depth of the olfactory sulcus at the level of the PPTE was smaller in patients with IA than in control subjects. The depth of the olfactory sulcus was greater on the right than on the left, and there was no overlap. Among patients with IA, the depth of the olfactory sulcus differed significantly between those with and those without visible olfactory tracts.

CONCLUSION

The depth of the olfactory sulcus at the level of the PPTE reflects the presence of olfactory tracts. The presence or absence of the olfactory tract may therefore have some association with cortical growth of the olfactory sulcus region. The olfactory sulcus is deeper on the right than on the left, particularly in patients with IA. We speculate that olfaction may be processed predominantly in the right hemisphere.

Tremor in otosurgery: influence of physical strain on hand steadiness

BACKGROUND

The microscopically small middle ear structures require the otosurgeon to have a steady hand because instrument stability is a critical factor for a successful microsurgical procedure. Hand steadiness is mainly influenced by the tremor movements of the hand. The aim of this study was to measure hand tremor under simulated microsurgical conditions and to estimate the influence of different kinds of physical strain (e.g., physical exertion and hand exercise), as well as food abstinence and coffee consumption. Further, the effect of one-or two-handed manipulation and microsurgical experience was investigated.

METHODS

The hand movements of 16 adult subjects were assessed during a defined manual manipulation using a stapes model to simulate microsurgical procedures. A laserinterferometric-based displacement technique was developed to measure tremor amplitude and frequency, as well as maximum displacement, to evaluate the subjects' fine motor skills.

RESULTS

The mean tremor frequency across all measurements was 8.1 Hz and did not show any dependence on different kinds of physical strain. Two-handed manipulations showed significantly lower tremor amplitudes than one-handed performances. Tremor amplitude and maximum displacement did not change after hand exercise, food abstinence, and coffee consumption. However, after physical exertion, a significant increase in the tremor amplitude was found. Subjects with advanced microsurgical experience showed smaller tremor amplitudes for one-handed runs.

CONCLUSION

The tremor data are interpreted as a recommendation to avoid physical exertion before microsurgery. In cases of absolute necessity for hand steadiness, two-handed manipulations are preferable. Further, hand steadiness might be improved by microsurgical training and experience.

A threshold-like measure for the assessment of olfactory sensitivity: the "random" procedure

Many tests of olfactory dysfunction are either too complex, too expensive, or too time-consuming to be of use in routine clinical testing. Thus, the present multicenter study was undertaken to investigate a new approach, the so-called "random" test. In this test different concentrations of citronellal and phenyl ethyl alcohol are applied according to a pre-established order; patients are asked to identify the odor if possible. The test score is the sum of correctly identified odors. Test administration takes about 10 min. Two studies were performed. Basic characteristics of the test were explored in experiment 1 in 176 healthy subjects (76 male, 100 female; age 12-85 years, mean age 30 years), namely test-retest reliability, correlation with other measures of olfactory sensitivity, and sensitivity of the test to differences in age and gender. In the second experiment the test was tried in 97 patients (45 male, 52 female; age 19-78 years, mean age 47 years) in a clinical environment to investigate its usefulness in diagnosing olfactory loss. The "random"-test was found (1) to exhibit a test-retest reliability similar to that reported for established measures of olfactory function (r = 0.71; P < 0.001), (2) to correlate with other measures of olfactory sensitivity (0.82 > r > 0.60; P < 0.001), (3) to differentiate between expected differences in olfactory sensitivity in relation to gender (t > 2.602, P < 0.011), and (4) to discriminate between different degrees of olfactory loss (F > 36.6, P < 0.001). Based on these data, and the fact that the new test requires little time and is easy to use, this approach can be expected to suit clinical needs.

Middle ear mechanics and their interface with respect to implantable electronic otologic devices

The understanding of construction principles of the middle ear and its mechanical behavior is valuable in the development of implantable hearing aids, as these devices have to adapt to the mechanics of the normal middle ear for optimal function. The input of the vibrational energy of a transducer into the ossicular chain follows the same mechanical fundamentals as in passive prostheses. Many aspects of middle ear mechanics, which are relevant for the acoustic quality of ossicular prostheses thus are also applicable for implantable transducers: the direction of vibrational mode, the stability of the contact zone between driver and ossicles, the increase of mass and impedance of the vibratory elements in the middle ear, the performance at changes of ambient air pressure, the potential feed back effects, and so forth.

Frequency and localization of the putative vomeronasal organ in humans in relation to age and gender

OBJECTIVES/HYPOTHESES

In many species the vomeronasal organ (VNO) serves as a chemosensory organ in addition to the olfactory system. The present investigation was undertaken to study 1) the frequency of monolateral or bilateral detection of the putative VNO (pVNO) in humans, 2) its localization in humans, and 3) whether detectability of the pVNO varies with age or gender.

STUDY DESIGN

Prospective.

METHODS

A total of 173 subjects participated in this study (88 women and 85 men; age range, 2-91 y). Inspection of the nose was performed with a speculum and a 30 degrees endoscope. The exact localization of the VNO was measured with custom-built rulers.

RESULTS

The study revealed the following major results: 1) A pVNO is detectable in approximately two-thirds of the population and bilateral pVNOs are present in approximately 40% of investigated subjects, 2) its localization on the left and right nasal septum is almost symmetrical, and 3) and detectability of the pVNO is not related to age or gender.

CONCLUSIONS

The present data indicated that the pVNO is present in approximately two-thirds of the population. This value may be biased by methodological or biological factors; nevertheless, it indicates that the pVNO is not observed in all humans regardless of age and gender. Thus, considering its variability in shape and immunohistochemical characteristics and the missing nerval connections between the peripheral "organ" and the central nervous system, the present results are not suited to argue for a functional significance of the pVNO in humans.

[Visualization of cochlear implant electrode movements in the cochlea by using x-ray microscopy]

BACKGROUND

The movements of the electrode cable of a cochlear implant inside the cochlea during the insertion procedure generally are invisible, even in temporal bone experiments. Yet, the development of new designs of electrodes, their positioning near to the modiolus etc. requires an exact knowledge on the dynamic behaviour of the electrodes inside the cochlea. The exclusive method for looking through the undamaged cochlea walls is by x-ray technique.

METHODS

A specific x-ray tube with a focal spot size of barely 5 microns allows useful direct magnifications of more than 20-30 times. We performed temporal bone experiments with this tube and studied the behaviour of conventional and perimodiolar electrode cables of a MedEl-Cl during the insertion procedure under fluoroscopic viewing.

RESULTS

The high resolution imaging revealed the influence of stiffness of the electrode cable on the insertion depth of a conventional electrode. If the angle of the direction of insertion was too steep, the resulting kinking of the cable at the medial wall of the basal turn was instantly visible. The direct visualisation of the movements of the cable was useful in optimizing the design and stiffness of various prototypes of perimodiolar electrodes for a deep insertion.

CONCLUSIONS

The dynamic examination technique disclosed that the stiffness of actual electrode cables is not optimally adapted to the form of the cochlear cavity for deep insertion. The non-destructive visualisation technique will facilitate the development of advanced electrode design, especially for various concepts of perimodiolar electrodes.

[Intraoperative measurement of stapes mobility using a hand-guided electromagnetic probe]

BACKGROUND

The hearing results of otosurgery are still unsatisfactory. Even after successful implantation of middle ear prostheses there often remains an air bone gap of 30 dB or more. As possible reasons dislocation of the prostheses due to scar growth, changes in prostheses' attachment or ventilation disorders are being discussed. Decreased stapes mobility, which has been judged only manually up to now, is supposed to be a further reason.

METHOD

We are introducing a new electromagnetic probe. The output signal of this device is proportional to the impedance of the stapes-annular ligament cochlear fluid system at the sensor's resonance frequency (2.4 kHz). The advantage of this system is characterised by its hand-guidance. Injury of the sensitive stapes-annular ligament due to tremor movements of the surgeon can be excluded using a special construction of the sensor head. The maximum force of the sensor's tip onto the stapes during measurement is limited to below 5 mN.

RESULTS

Preliminary measurement results of 20 patients are presented with normal and abnormal stapes mobility. These results are compared to the subjective impression of the surgeon, who usually tested the stapes mobility by hand. As a result of our investigations probe measurements can detect more exactly decreased mobility of the stapes than the surgeon.

CONCLUSIONS

Our device may help to detect latent stapes fixation caused by chronic inflammation of the middle ear. The intraoperative measurement of stapes mobility may influence the strategy of the surgeon. Furthermore it would be helpful in patient consulting prior to a revision-tympanoplasty with predicting the potential hearing improvement.

[Normal sense of smell in Kallmann syndrome. A case report]

BACKGROUND

Kallmann's syndrome (KS) was first mentioned in 1944 as an association of anosmia and hypogonadotropic hypogonadism. Causes are multiple genetic defects the most common of which is the x-linked KS appearing mostly in men. However, autosomal dominant and autosomal recessive forms have also been described.

PATIENT

We present a case of KS with normosmia (male, 39 years of age). All symptoms of hypogonadotropic hypogonadism were present.

RESULTS

Psychophysical olfactory testing revealed left-sided anosmia with right-sided normosmia which was confirmed by electrophysiological measures of olfactory function. Magnetic resonance imaging indicated aplasia of the left olfactory tract and bulb, whereas the right-sided structures appeared to be normal.

CONCLUSIONS

As indicated in this case with lateralized anosmia and contralateral normosmia, overall olfactory function strongly depends on the "best" nostril. Therefore, in many clinical situations, lateralized olfactory testing appears to be extremely important.

[The enjoyment of red wine is influenced by the shape of the wine glass]

BACKGROUND

It is frequently claimed that the glass shape has a direct impact on wine aroma. METHODS, PATIENTS: Healthy volunteers (43 m, 46 f, age 19-60 years) tried 3 glasses. Three glasses of different shape but of the same height and of comparable opening diameter were used. Glasses were of "tulip"-like, "beaker"-like, and "egg"-like shapes. Intensity, hedonic tone, and quality of a red wine were rated before and after drinking.

RESULTS

Both intensity and hedonic ratings of wines from different glasses were influenced by glass shape. Glass shape also influenced the complexity of wine odors. This appeared not to be related to the esthetic impression the glasses made.

CONCLUSIONS

The present data indicate that egg-shaped glasses, compared to "tulip" or "beaker" glasses, appear to produce higher intensity and higher complexity of wine odors. This may relate to the trapping of odors in egg-shaped glasses.

Imaging of the human vomeronasal duct

The human vomeronasal duct (VND) is described as a tubular or pouch-like mucosal invagination of the anterior nasal septum. This study investigated shape, size and orientation of the VND using magnetic resonance imaging (MRI). Fifteen subjects participated (eight women, seven men; mean age 39 years, age range 18-66 years); they had been pre-selected with regard to the presence of a VND opening of 1 mm. MRI was performed before and after application of diluted gadolinium-diethylene-triamino-penta-acetic actetate (Gd-DTPA) into the left or right VND. A tubular structure was found in 12 subjects with a median length of 7 mm (range 3-22 mm; one VND with a length 47 mm). In three subjects a nearly circular, pouch-like structure was observed. Seven of the tubular VNDs were slightly bent upwards, the other five VNDs ran parallel to the floor of the nasal cavity. There was no significant gender-related difference in the length of VNDs. These data indicate considerable variability of shape, size and orientation of the human VND.

Biomechanical aspects in implantable microphones and hearing aids and development of a concept with a hydroacoustical transmission

The middle ear functions as a sensitive pressure receptor. This implies that it not only transmits sound pressure waves with molecule-sized vibrational amplitudes, but that it also reacts to the million times larger variations of ambient air pressure. This pressure induces movements of the tympanic membrane and of the attached ossicular chain of up to 1,000 microm. Any artificial device that contacts these sound-transporting elements, be it a receiver for an implantable microphone or a transducer for an implantable hearing aid, has to respect these two different modes of biomechanical behavior. A hydroacoustical transmission system has therefore been developed consisting of a water-filled flexible tube, which contacts the ossicular chain with a balloon tip, and which is connected to a piezo-electric transducer at its other end. This soft contact prevents a localized pressure load and does not restrain the free movement of the underlying ossicle during ambient pressure variations. Temporal bone experiments showed that the device transmits vibration energy in good acoustical quality. The device can also be used in a reverse mode, working as a microphone, for example for a totally implantable hearing aid or a cochlear implant. This microphone concept has the advantage that it incorporates the biologic sound receiving components (the tympanic membrane and the ossicular chain micromechanics) into a technical device.