Quantitative assessment of methods for the detection of otoacoustic emissions.

Objective: To compare the performance of various types of signal detector commonly used to detect otoacoustic emissions (OAEs).

Method: The signal detectors were tested with signals in various types of noise, including noise with various amplitude distributions. Commonly utilized transient evoked OAE and distortion product OAE detectors were analyzed.

The objective assessment of transient evoked otoacoustic emissions in neonates.

Objective: To develop a simple objective method for assessing the presence or absence of a TEOAE in recordings from neonatal ears.

Design: Several simple, objective methods of transient evoked otoacoustic emissions (TEOAE) assessment were tested against a verified subjective assessment method, using 200 neonatal TEOAEs recorded under clinical conditions.

Results: Total TEOAE level did not correlate well with the subjective assessment.

Objective assessment of endoscopic sinus surgery in the management of chronic rhinosinusitis: an update.

Whilst clinical success of endoscopic surgery for chronic rhinosinusitis has necessarily depended primarily upon subjective evaluation, a range of objective techniques are now available which may facilitate our interpretation of results. A group of 200 patients underwent assessment of symptoms by sequential visual analogue scoring, olfaction by qualitative and quantitative testing, nasal airflow by forced inspiratory peak flow, anterior rhinomanometry, nasomucociliary function by ciliary beat frequency and nasal topography by acoustic rhinometry performed pre- and post-operatively. Significant improvement was demonstrated in all symptoms examined, olfactory tests and ciliary beat frequency whilst acoustic rhinometry provided an attempt to quantify the surgical cavities.

Contralateral suppression of transiently evoked otoacoustic emissions and neuro-otology.

Transiently evoked otoacoustic emissions can be suppressed with simultaneous contralateral sound stimulation. This is considered to be effected via the efferent pathway from the superior olivary complex (SOC) to the contralateral cochlea. This study examined this effect in patients with extrinsic and intrinsic lesions of the brainstem which may affect the efferent pathway either within the vestibular nerve which carries the efferent bundle to the cochlea or within the brainstem at the level of the SOC.

Effects of unilateral deafening on the cochlear nucleus of the guinea pig at different ages.

Developmental changes in spherical cell sizes were measured in the ventral cochlear nucleus (VCN) in normal guinea pigs aged 2 days and 2, 7 and 12 weeks to establish the time course of postnatal neuronal growth, as a baseline for our experimental work. A continued growth of spherical cell size was observed in the VCN up to 7 weeks postnatally. Animals were unilaterally deafened by cochlear perfusion with kanamycin sulphate at ages 1 and 6 weeks.

Freeze fracture analysis of apical membranes in cochlear cultures: differences between basal and apical-coil outer hair cells and effects of neomycin.

Previous studies have shown that exposure of cochlear cultures to the ototoxic aminoglycoside antibiotic neomycin leads to the rapid formation of numerous membrane filled protrusions on the apical surface of the hair cells but not on the surrounding supporting cells, and that hair cells in basal-coil cultures are more sensitive to these effects of neomycin than those in the distal end of apical-coil cultures. Freeze-fracture has been used to examine and compare the apical surfaces of hair cells and supporting cells in basal and apical-coil cultures in order to look for features that may explain the differential sensitivity of the various cell types to neomycin, and to characterize the membrane type that forms in response to neomycin and compare it with the normal apical membrane of the hair cell. The apical surface of the highly responsive basal-coil outer hair cells differs significantly from the apical surfaces of apical-coil outer hair cells and supporting cells in both regions of the cochlea in both surface area and the number and density of endocytotic vesicles associated with this surface.

Involvement of cytokines and vascular adhesion receptors in the pathology of fronto-ethmoidal mucocoeles.

Fronto-ethmoidal mucocoeles have the capacity to destroy bone. Sinus lining tissue has been obtained at surgery from patients with mucocoeles, from those with chronic sinusitis undergoing endoscopic sinus surgery and from patients undergoing craniofacial resection. Tissues have been frozen, sectioned, and subjected to immunohistochemical examination with monospecific antibodies for the presence of the potent osteolytic cytokines interleukins-1 and -6 and tumour necrosis factor alpha.

Laryngeal imaging by computerized tomography and magnetic resonance following radiation therapy: a need for caution.

For patients with laryngeal tumours, the use of computerized tomography (CT) or magnetic resonance imaging (MR) may facilitate accurate staging by the demonstration of cartilage invasion or tumour extension to areas such as the pre-epiglottic space. The role of imaging in the follow-up of patients after radiotherapy, however, has not been examined. A prospective study of 18 patients undergoing laryngectomy was performed.

Ewing's sarcoma of the nose.

Ewing's sarcoma is a bone tumor that rarely arises in the head and neck region. Head and neck tumors account for only 2% to 3% of all Ewing's sarcomas. There is an extremely rare subgroup of Ewing's tumors, that are histologically indistinguishable, which are not metastatic and arise in soft tissue rather than bone.

Ultrastructural evidence for hair cell regeneration in the mammalian inner ear.

It has long been thought that hair cell loss from the inner ears of mammals is irreversible. This report presents scanning electron micrographs and thin sections of the utricles from the inner ears of guinea pigs that show that, after hair cell loss caused by treatment with the aminoglycoside gentamicin, hair cells reappeared. Four weeks after the end of treatment, a large number of cells with immature hair bundles in multiple stages of development could be identified in the utricle.

Analyses of Mössbauer mechanical measurements indicate that the cochlea is mechanically active.

Using the results of Mössbauer measurements, mechanical activity in the cochlea was tested for by comparing the measured basilar membrane (BM) transverse velocity amplitude with that calculated for a lossless mechanically passive system, derived from the measured BM velocity phase. If the cochlea is considered to be a lossless mechanically passive system, then the transverse velocity amplitude can be calculated from the group velocity and the relative variation of stiffness along the BM. The group velocity can be derived from the Mössbauer phase measurements, and the relative variation of stiffness along the BM can be derived from the frequency map of the cochlea.

Olfactory neuroblastoma: clinical and pathological aspects.

Twenty cases of olfactory neuroblastoma were available for clinical and histopathological evaluation. The usefulness of immunohistochemistry in the diagnosis of this tumour was investigated and was best achieved using a panel of monoclonal and polyclonal antibodies, notably neuron-specific enolase, PGP 9.5, S-100 protein, synaptophysin and chromogranin A.

Suppression of stimulus frequency otoacoustic emissions.

Observations of the suppression of stimulus frequency evoked otoacoustic emissions (SFOAEs) by a second tone were made in human subjects. Measurements were made with the suppressor tone at frequencies and levels at, above, and below the stimulus tone generating the SFOAE. Data were collected with the stimulus tone at a range of levels (20-60 dB SPL), over a range of frequencies and in six different ears, in three subjects.

Structural variability of the sub-surface cisternae in intact, isolated outer hair cells shown by fluorescent labelling of intracellular membranes and freeze-fracture.

The intracellular membrane systems in intact, isolated outer hair cells were visualised using the fluorescent membrane probe 3,3'-dihexyloxacarbocyanine iodide (DiOC6) and by freeze-fracture, and f-actin distribution was examined with rhodamine-phalloidin. DiOC6 stained the sub-surface cisternal membranes in the lateral wall and revealed a membrane system running in the centre of the cell from the nucleus to the sub-cuticular region. In optical sections of the lateral wall of fluorescently labelled cells, obtained by scanning laser confocal microscopy, the sub-surface membrane appeared as a fenestrated sheet or a fine network of tubules.

[Hypoacusis and tinnitus: an overview].

An overview of hearing loss and tinnitus deals with the evaluation and measurement of auditory function and the factors which influence hearing. The change in the threshold of hearing with age shows a basic pattern, which is also observed in many auditory disorders. Characteristically, the audiogram is bisegmental, with change in threshold being a linear function of log frequency.

The midfacial degloving approach to sinonasal disease.

The midfacial degloving approach was first described by Casson et al. in 1974 but despite a number of papers in the American literature advocating its use, it has not gained popularity in Europe. The advantages and application of the technique are presented in 36 patients, ranging from 7-78 years of age.

Office evaluation of nasal obstruction.

It is evident from the foregoing that the evaluation of such a common complaint as nasal obstruction can be extremely complex. If a thorough history and examination are undertaken, however, only a small number of these investigations (if any) may be required. In each individual, it is always worth considering possible predisposing factors.

Scanning electron microscopy of the mammalian organ of Corti: assessment of preparative procedures.

Different fixation, drying and coating procedures have been applied in preparation of the organ of Corti for scanning electron microscopy (SEM), and structural features of the apical surface of the tissue in unfixed, freeze-fractured preparations used in assessing their effects on morphology. Fixation with glutaraldehyde alone or osmium tetroxide alone causes artefacts that are substantially avoided when tissue is doubly fixed in glutaraldehyde followed by osmium. Significant improvements in preservation are also obtained when tissue is additionally processed through thiocarbohydrazide-osmium (TOTO) processing.

Occupational noise induced vestibular malfunction?

This paper comprises a review of the evidence for the possibility that exposure to noise may damage the vestibular receptors in the internal ear as well as those in the cochlea. The review covers lay and medical publications, observations on patients, experimental studies, and compensation claims. It concludes that the verdict must be "not proven"--that is, although such damage is possible, the evidence is not strong enough to regard it as probable.

Endoscopy and endoscopic photography in ENT.

Doctors have been concerned with ear, nose and throat (ENT) diseases since the earliest times, but there was no single specialty before the introduction of endoscopic methods last century. Effective visualization of the ears, nose and throat poses significant problems for the medical illustrator today. The development of endoscopy and endoscopic photography is outlined with background information to help the illustrator who has to work in this field.

Immunologic aspects of chronic sinusitis.

The role of immunological defence mechanisms in the development of acute recurrent or chronic sinusitis is obviously of considerable importance but the incidence of such immune problems is unknown. To elucidate this situation, a prospective study of 47 patients with chronic rhino-sinusitis were examined for abnormalities of serum immunoglobulins, both major class and subclasses. Deficiencies of minor IgG subclasses may be obscured by only measuring the major IgG class and should be specifically sought in clinically suspicious cases.