In vitro considerations in the production of dimensionally accurate earmoulds. I. The ear impression

As the first part of a study on the fabrication of earmoulds, the dimensional accuracy and stability, as a function of time, of a wide range of polymer-based impression materials has been studied. The results demonstrate that addition cured silicones are the most promising materials in terms of their accuracy and dimensional stability.     

In vitro considerations in the production of dimensionally accurate earmoulds. II. The earmould material

In the first part of this work, the accuracy of impression materials was studied. In the present paper, the dimensional accuracy of a range of hard and soft polymeric earmould materials was studied and found to be a function of choice of material, processing equipment, curing cycle, time after processing, and choice and storage time of impression material. It was noted that generally speaking the overall shrinkage of a two-stage specimen is approximately equal to the sum of the impression shrinkage plus processing shrinkage. Clinical trials are now being conducted to assess the real ear performance of earmoulds as a function of material accuracy and flexibility.     

Factors influencing the efficacy of light cured materials for earmoulds.

This work was undertaken to investigate two systems for producing light-cured earmoulds, in order to evaluate the factors which influence the efficacy of such procedures. It was shown that there were variations in light intensity in the light boxes, and that the depth and age of gel in which curing takes place was important. Degree of cure of the materials was assessed by hardness measurements for hard materials and resistance to tearing for hard materials. Light-cured technology has great potential for the rapid production of earmoulds.     

Practical considerations of real-ear-to-coupler difference measures in infants

The purpose of this study was to investigate some of the practical issues surrounding the use of the real-ear-to-coupler difference (RECD) measure in infants in clinical settings. Twenty-two newborns were seen once a month during their first year of life for the purpose of obtaining RECD measurements. Two methods for obtaining the RECD were examined: the commonly used constant insertion depth method and the acoustic method. Differences between the results of the two methods were examined as well as test-retest reliability for each. Findings suggest that no compelling evidence exists to support the use of one of these methods over the other. Use of either method resulted in good test-retest reliability in the midfrequency range of the RECD, with poorer reliability on both ends of the frequency spectrum. Test-retest reliability decreased with increasing age for both methods. In addition, reliability of between-ear RECD values was examined. Between-ear measurements were most reliable in the midfrequency range, and reliability decreased slightly with increasing age.     

Practical considerations for the application of ear simulators in the calibration of audiometers in the extended high frequency region

Objective: Calibration service providers for audiometric equipment often encounter impracticalities in fully implementing the International Electrotechnical Commission (IEC) guidelines for the extended high frequency region. This report evaluates some of the work-around solutions sometimes employed in practice and the implications these have for audiometer calibration results and uncertainties. Design: The impact of using four different microphone configurations on the ear simulator calibration in the frequency range 125?Hz to 20?kHz, and especially in the extended high frequency range from 10?kHz to 20?kHz, was investigated, at a range of temperatures. Results: Variations in the response of the ear simulator of up to 6?dB were observed with the different microphone configurations. In addition, using the microphone without its protection grid produced a dip in the high frequency response of approximately 15?dB. Conclusion: While deviation from the practices required in IEC standards is not recommended, replacing the microphone protection grid with a specially fabricated collar (essentially a grid with the top removed) was found to constrain deviations in response to within ±2?dB. It was also concluded that simply removing the microphone protection grid resulted in a wholly unsatisfactory performance.     

Endolymphatic hydrops evaluation on MRI: Practical considerations

Four-hour delayed three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) sequence after intravenous gadolinium-based contrast agent administration is an optimal magnetic resonance imaging technique to evaluate endolymphatic hydrops in patients with known or suspected Ménière's disease. Nonenhanced endolymphatic space surrounded by enhanced perilymphatic space is evaluated in the cochlea and vestibule separately. In cochlear hydrops, the scala media is enlarged, potentially obliterating the scala vestibuli. In vestibular hydrops, the size of the saccule becomes equal to or larger than that of the utricle; as hydrops progresses, the saccule and utricle become larger and confluent until complete obliteration of the vestibule's perilymphatic space.In patients with a unilateral clinical presentation of Ménière's disease, it is possible to depict the asymmetries of perilymph enhancement, which may be increased on the affected side and reflect a permeability alteration of the blood-perilymph barrier. In addition, endolymphatic hydrops can be observed in the asymptomatic ear of these patients with a unilateral clinical presentation, showing that Ménière's disease tends to undergo bilateral evolution over time.     

A comparison of the effects of different methods of impression build-up on earmoulds

An investigation was carried out into effects of three types of impression build-up (patting down of impressions, special earmould-maker build-up and the multistage impression technique) on the dimensions, static pressure seal, degree of acoustic seal and the subjective tightness and comfort of earmoulds. Patting down the impression significantly improved the degree of acoustic seal provided by earmoulds without making them feel tighter or less comfortable. However, special build-up was much more effective than patting down and the multistage impression technique was slightly more effective than special build-up in improving the degree of acoustic seal. The improvement in acoustic seal provided by both multistage and specially built-up earmoulds can usually be obtained without an unacceptable level of discomfort. Patting down the impression did not improve the chance of obtaining a static pressure seal. Special build-up of the impression by the earmould-maker significantly increased the proportion of earmoulds which provided a static pressure seal but an even higher proportion of earmoulds made from multistage impressions provided a seal. Dimension results indicated that an increase in earmould-maker build-up of the minor axis at the beginning of the canal segment of the impression would improve the acoustic seal provided by specially built-up earmoulds and that earmoulds with rounder tips are more likely to provide a static pressure seal than earmoulds with more elliptical tips. The better the impression material fills the ear canal, the rounder the tip of the impression, and the rounder the tip of the earmould made from the impression.     

Nontuberculous mycobacterial infections of the face and neck — Practical considerations

Cervicofacial nontuberculous mycobacterial (NTM) infections are a diagnostic and therapeutic dilemma which may be encountered by the Otolaryngologist. A review of the world's literature indicates that these infections are being diagnosed more frequently and that they far outnumber cervical infections by Mycobacterium tuberculosis. The organisms are ubiquitous. The portal of entry may be through a small defect in the skin or mucosa. They rarely, if ever, cause serious systemic illness. Diagnosis is by culture of the organism, however, cultures are usually not available at the time the patient is treated. Treatment, then, must be based on the results of skin tests, examination of pus and tissue, a “typical clinical presentation,” and elimination of other diseases. The differential diagnosis is extensive. This review reports 21 patients with proven or suspected NTM infections of the face and neck. Eight of these patients were treated by traditional methods utilizing complete excision and, in some cases, drug therapy. Eleven were treated by curettage alone, and two more by curettage and drugs. The results were excellent by all of these forms of treatment. These findings support the proposition that curettage is a simple, safe, and effective method of treatmenting cervicofacial NTM infections and should be utilized as the primary treatment in all suspected or proven cases of this disease. The method does not exclude other forms of treatment being utilized if they should be required.     

A comparison of three types of earmoulds in elderly users of post-aural hearing aids

The objective of this study was to assess the ease of handling, comfort, and general effectiveness of three types of earmould in patients who, due to their age, could be expected to experience handling difficulties. The three mould types were, meatal tip, skeleton and skeleton with the 'top prong' removed. The results indicated that the skeleton with the top prong removed was the best in all contexts but one. It was easiest and quickest to fit and least likely to be badly fitted. Only in feedback control did it perform less well. It was concluded that it should be routinely used for elderly patients fitted with low gain hearing aids.     

Acoustic evaluation of earmoulds in situ: a comparison of impression and earmould materials.

Laboratory research has been carried out on the accuracy of both ear impression and earmould materials. The present work was undertaken to assess such materials in vivo. An objective clinical method of earmould evaluation was developed, based on estimation of the attenuation in the acoustic feedback path. The method was used to assess the acoustic performance of earmoulds made from three earmould materials of different texture, when prepared from two different impression materials. It was shown that the choice of impression material made a significant difference to earmould performance. For greatest accuracy, addition cured silicone impression materials are recommended.     

Some physical considerations in the choice of techniques for ossiculoplasty.

A comparative study between the monobloc tympano-ossicular implant and the classical columellar technique is made. Although both give satisfactory audiometric results, the follow-up of the columellar restoration showed some post-operative disadvantages, namely: invagination and perforation of the tympanic membrane, slipping of the columella, and fixation of the columella to the tympanic ring (bony annulus) or to the promontory. In view of the normal tympano-malleal fixation, the normal static pressure accomodation in the incudo-malleal joint and the normal topological situation, monobloc implant obviates the disadvantages inherent in the columellar technique. Two aspects of the monobloc implant need further examination; these are the restoration of the correct rotation axes and the incudo-stapedial connection.     

Treatment considerations for head and neck cancer in the elderly

As life expectancy increases, surgeons can expect an increasing number of geriatric patients. In turn, the number of elderly patients presenting with head and neck cancer is likely to increase. Management of this subpopulation has become a source of debate because there is a paucity of randomized data regarding the effect of age on treatment response and morbidity associated with the treatment of head and neck cancer. The management of head and neck cancer in the elderly depends on the patient's age and general condition, the stage of disease, the effects of treatment on quality of life (such as speech and swallowing), patient and family wishes, and active physician participation in continued care. Elderly patient's comorbid conditions need appropriate attention especially if surgery is to be undertaken. The aim of this review is to examine the current literature in an attempt to develop an approach to the treatment of the elderly patient with head and neck cancer and to define the pertinent issues that require further study.     

Maturation of auditory steady-state responses in normal babies

OBJECTIVE: To track the development of the auditory steady-state response (ASSR) through the neonatal and early infant periods in a group of normal-hearing babies. DESIGN: This longitudinal study involved assessment at four data collection points. ASSR thresholds to modulated 500 Hz and 4 kHz tones were established in 20 full-term subjects at 0, 2, 4, and 6 wks of age. RESULTS: Significant developmental changes were observed for both test frequencies. Mean ASSR threshold levels decreased by approximately 10 dB between the week 0 and week 6 data collection points. CONCLUSIONS: The results of this study indicate that ASSR threshold levels in normal-hearing neonates and young infants are different from those observed in older subjects. Clinical application of the ASSR procedure in this population will need to take into account developmental changes occurring in the first weeks of life. Furthermore, the findings indicate that ASSR thresholds in normal-hearing babies at 6 wks of age are not yet mature.