Implant-associated Infection After Pediatric Spine Deformity Surgery: Is Removal of Hardware Indicated?

BACKGROUND

Postoperative spinal implant infection following pediatric spinal surgery often presents a management dilemma. We aimed to characterize our experience in this cohort of patients, hoping to provide further insight when approaching these challenging cases.

METHODS

A retrospective, observational study was performed of all children who underwent spinal surgery from January 2015 to June 2021 in a tertiary pediatric spinal surgery referral center in Queensland, Australia. Records were reviewed to identify cases of postoperative surgical site infection, with particular focus on children with infection directly involving implants. Preoperative prophylaxis, microbiology, clinical course and outcomes were analyzed.

RESULTS

A total of 580 children underwent 933 procedures during the study period. The most common pathology requiring surgery was idiopathic scoliosis in 257 children (44.3%) followed by neuromuscular scoliosis in 192 children (33.1%). There were 35 cases of surgical site infection (6.03%), and 9 were implant-associated (1.55%). Infection rate among children with neuromuscular spinal deformity was almost 3-fold higher (11.5%) than idiopathic (3.89%). Methicillin-sensitive Staphylococcus aureus was the most commonly isolated organism (n = 15). Four implant-associated infections were successfully managed with retention of implant; all were diagnosed within 32 days (median = 20 days) and cultured either Staphylococcus aureus or Pseudomonas aeruginosa . Conversely, infections that necessitated implant removal had a more indolent onset (median = 175 days), and more often cultured Cutibacterium acnes and coagulase-negative Staphylococci .

CONCLUSIONS

Postoperative spinal implant infection can be treated successfully with hardware retention in select cases. Earlier presentation and recognition appear to be associated with better rates of retention and are linked to certain organisms. Further exploration of specific preventative strategies may be key in preventing devastating late-onset infections.

The influence of the energy of trauma, the timing of decompression, and the impact of grade of SCI on outcome

Study design: Retrospective cohort study.

Objectives: To find out: (1) if the energy of trauma (high and low) influence the outcome after cervical spinal cord injury; (2) if time to decompression and degree of injury (complete and incomplete) influence the outcome after high- and low-energy cervical spinal cord injury.

Methods: Twenty-one consecutive patients with low-energy cervical spinal cord injury were identified from the spinal injuries unit database (eg, ball sports, diving, surfing, and falls). Twenty-one aged-matched patients with high-energy cervical spinal cord injury (eg, motor vehicle trauma) were then randomly selected and the groups were compared. All patients had formal American Spinal Injuries Association assessment on admission and at 6 months.

Results: At the 6-month follow-up, the energy of the initial trauma was not found to influence the neurological outcome (P = .76). Early definitive intervention (<8 hours) for patients with incomplete cord lesions was shown to significantly affect outcome (P = .049). As expected, patients with an incomplete spinal cord injury at presentation showed significantly greater neurological improvement at follow-up compared with those with complete injuries (P = .006).

Conclusions: We were unable to find a correlation between the energy of the initial trauma causing a spinal cord injury and the neurological outcome. Early definitive decompression improved outcomes for patients with spinal cord injury, especially those with incomplete spinal cord injury.

The impact of measurement goals on the design specification for outcome measures

No outcome measure has universal validity and applicability. When designing, promulgating or selecting a particular instrument, audiologists should take care to consider and specify the detailed purposes to which the measure will be directed, and the particular populations to which it will be applied. Scales that have been optimized in one arena will have limited (though perhaps still useful) generalizability. The importance dimensions of difference between applications are numerous.

Optimal outcome measures, research priorities, and international cooperation

The participants in the Eriksholm Workshop on "Measuring Outcomes in Audiological Rehabilitation Using Hearing Aids" debated three issues that are reported in this article. First, it was agreed that the characteristics of an optimal outcome measure vary as a function of the purpose of the measurement. Potential characteristics of outcome self-report tools for four common goals of outcome measurement are briefly presented to illustrate this point. Second, 10 important research priorities in outcome measurement were identified and ranked. They are presented with brief discussion of the top five. Third, the concept of generating a brief universally applicable outcome measure was endorsed. This brief data set is intended to supplement existing outcome measures and to promote data combination and comparison across different social, cultural, and health-care delivery systems. A set of seven core items is proposed for further study.

A self-report outcome measure for the evaluation of hearing aid fittings and services

OBJECTIVE

To design, optimise and validate an outcome measure for the evaluation of adult hearing aid fittings.

DESIGN

A multi-dimensional subject-specific and situation-specific questionnaire (the Glasgow Hearing Aid Benefit Profile--GHABP) to assess initial disability, handicap, use, benefit, residual disability and satisfaction before and after hearing aid provision.

SUBJECTS

Hearing-impaired adults attending National Health Service clinics for the first time for whom amplification is an appropriate management option.

RESULTS

A self-report instrument of length compatible with the requirements of routine clinical practice which retains psychometric leverage. The GHABP demonstrates sensitivity to the technological content and rehabilitative context of interventions. The scale properties facilitate the use of the GHABP in decision-making for individual hearing-impaired patients.

CONCLUSION

An outcome measure such as the GHABP offers the various interested parties (purchasers, providers and patients) a tool for use in the evaluation of the effectiveness and cost effectiveness of existing services and future developments. Many of the design concepts embodied in the GHABP are applicable in other healthcare contexts.

Sound localization in noise in hearing-impaired listeners

The present study assesses the ability of four listeners with high-frequency, bilateral symmetrical sensorineural hearing loss to localize and detect a broadband click train in the frontal-horizontal plane, in quiet and in the presence of a white noise. The speaker array and stimuli are identical to those described by Lorenzi et al. (in press). The results show that: (1) localization performance is only slightly poorer in hearing-impaired listeners than in normal-hearing listeners when noise is at 0 deg azimuth, (2) localization performance begins to decrease at higher signal-to-noise ratios for hearing-impaired listeners than for normal-hearing listeners when noise is at +/- 90 deg azimuth, and (3) the performance of hearing-impaired listeners is less consistent when noise is at +/- 90 deg azimuth than at 0 deg azimuth. The effects of a high-frequency hearing loss were also studied by measuring the ability of normal-hearing listeners to localize the low-pass filtered version of the clicks. The data reproduce the effects of noise on three out of the four hearing-impaired listeners when noise is at 0 deg azimuth. They reproduce the effects of noise on only two out of the four hearing-impaired listeners when noise is at +/- 90 deg azimuth. The additional effects of a low-frequency hearing loss were investigated by attenuating the low-pass filtered clicks and the noise by 20 dB. The results show that attenuation does not strongly affect localization accuracy for normal-hearing listeners. Measurements of the clicks' detectability indicate that the hearing-impaired listeners who show the poorest localization accuracy also show the poorest ability to detect the clicks. The inaudibility of high frequencies, "distortions," and reduced detectability of the signal are assumed to have caused the poorer-than-normal localization accuracy for hearing-impaired listeners.

Speech tests as measures of outcome

Speech tests comprise an important and integral part of any assessment of the effectiveness of intervention for hearing disability and handicap. Particularly when considering hearing aid services for adult listeners, careful consideration has to be given to the particular form and application of inferences drawn from speech identification procedures if erroneous conclusions are to be avoided. It is argued that four such components relate to the statistical properties and discriminatory leverage of speech identification procedures, the choice of presentation level and conditions in regard to the auditory environment experienced by hearing-impaired clients, the extent to which speech tests based on segmental intelligibility provide appropriate information in relationship to perceived disabilities and handicaps, and the ways in which speech identification procedures to evaluate the potential benefits of signal-processing schemes for hearing aids are dependent upon sufficient listening experiences. Data are drawn from the literature to illuminate these points in terms of application in clinical practice and clinical evaluation exercises, and also with regard to future research needs.

Sound localization in noise in normal-hearing listeners

The ability to localize a click train in the frontal-horizontal plane was measured in quiet and in the presence of a white-noise masker. The experiment tested the effects of signal frequency, signal-to-noise ratio (S/N), and masker location. Clicks were low-pass filtered at 11 kHz in the broadband condition, low-pass filtered at 1.6 kHz in the low-pass condition, and bandpass filtered between 1.6 and 11 kHz in the high-pass condition. The masker was presented at either -90, 0, or +90 deg azimuth. Six signal-to-noise ratios were used, ranging from -9 to +18 dB. Results obtained with four normal-hearing listeners show that (1) for all masker locations and filtering conditions, localization accuracy remains unaffected by noise until 0-6 dB S/N and decreases at more adverse signal-to-noise ratios, (2) for all filtering conditions and at low signal-to-noise ratios, the effect of noise is greater when noise is presented at +/- 90 deg azimuth than at 0 deg azimuth, (3) the effect of noise is similar for all filtering conditions when noise is presented at 0 deg azimuth, and (4) when noise is presented at +/- 90 deg azimuth, the effect of noise is similar for the broadband and high-pass conditions, but greater for the low-pass condition. These results suggest that the low- and high-frequency cues used to localize sounds are equally affected when noise is presented at 0 deg azimuth. However, low-frequency cues are less resistant to noise than high-frequency cues when noise is presented at +/- 90 deg azimuth. When both low- and high-frequency cues are available, listeners base their decision on the cues providing the most accurate estimation of the direction of the sound source (high-frequency cues). Parallel measures of click detectability suggest that the poorer localization accuracy observed when noise is at +/- 90 deg azimuth may be caused by a reduction in the detectability of the signal at the ear ipsilateral to the noise.

Measuring patient benefit from otorhinolaryngological surgery and therapy

The Glasgow Benefit Inventory (GBI) is a measure of patient benefit developed especially for otorhinolaryngological (ORL) interventions. Patient benefit is the change in health status resulting from health care intervention. The GBI was developed to be patient-oriented, to be maximally sensitive to ORL interventions, and to provide a common metric to compare benefit across different interventions. The GBI is an 18-item, postintervention questionnaire intended to be given to patients to fill in at home or in the outpatient clinic. In the first part of the paper, five different ORL interventions were retrospectively studied: middle ear surgery to improve hearing, provision of a cochlear implant, middle ear surgery to eradicate ear activity, rhinoplasty, and tonsillectomy. A criterion that was specific to the intervention was selected for each study, so that the patient outcome could be classified as above and below criterion. In all five interventions, the GBI was found to discriminate between above- and below-criterion outcomes. The second part of the paper reports on the results and implications of a factor analysis of patient responses. The factor structure was robust across the study, and so led to the construction of subscales. These subscales yield a profile score that provides information on the different types of patient benefit resulting from ORL interventions. The GBI is sensitive to the different ORL interventions, yet is sufficiently general to enable comparison between each pair of interventions. It provides a profile score, which enables further breakdown of results. As it provides a patient-oriented common metric, it is anticipated that the GBI will assist audit, research, and health policy planning.

Report of the Eriksholm Workshop on auditory deprivation and acclimatization

The terminology used in studies documenting changes in auditory performance following fitting of hearing aids has been diverse. Definitions for the auditory deprivation effect and auditory acclimatization are offered as a first step in rationalization. Two statements summarize current knowledge concerning auditory deprivation effects and auditory acclimatization, as well as considering the potential implications for research, field trial and clinical practice applications. Potential areas for future research are identified.

Test-retest reliability of loudness scaling

OBJECTIVE

Establish the test-retest reliability of loudness scaling using a bounded category rating method.

DESIGN

The individual loudness functions were investigated in three groups of listeners: seven normal-hearing listeners age 18 to 35 yr, five normal-hearing listeners aged 57 to 84 yr, and five listeners aged 54 to 82 yr with bilateral sloping sensorineural hearing loss. Test-retest reliability was investigated by determining the intralistener, between-session standard deviation.

RESULTS

The pattern of test-retest reliability was similar across all three groups. It improved as the intensity of the stimulus increased: 7 dB at the first quartile of the loudness function, and 3 dB at the third quartile. Two to four runs of the task appear to be sufficient to obtain a stable loudness function, and it was shown that an exponential function provided a better goodness of fit than a linear function (r2: 0.99 compared with 0.94).

CONCLUSIONS

Loudness scaling is a longer test than most conventional suprathreshold measures and requires special equipment. However, it has good test-retest reliability and provides more information on the loudness function that might be useful in the fitting of nonlinear hearing aids. The data show that an exponential function provides a good fit to the loudness growth data, and should probably be incorporated into fitting algorithms associated with loudness scaling.

The value of routine in-the-ear measurement of hearing aid gain

When selecting the frequency response of a hearing aid, a target is usually selected using a predictive formula from the international literature. Nowadays real ear measurements can readily be carried out to ensure that the real ear gain closely matches the prescribed target. Such measurements are usually only carried out on a subset of patients fitted in the UK, though it has been suggested that they should be carried out on all hearing aid prescriptions. Real ear insertion gains were measured on 319 first-time National Health Service (NHS) hearing aid issues. A total of 181 (57%) failed to come within 10 dB of the target gain at one or more frequencies between 0.25 and 3 kHz. Though there were audiometric differences between those who achieved satisfactory gain and those who did not, there was too much overlap between groups to make any audiometric index or combination of indices of value in predicting the likelihood of failure to achieve target gain. Sixty-eight patients with inadequate real ear gain were invited to attend for alterations to their hearing aid prescription. Twelve (18%) were fitted with a high frequency aid, while the rest were managed by alterations to their NHS aid or to the earmould and tubing. After appropriate changes, 58 (85%) achieved a satisfactory gain. The routine use of real ear insertion gains in all hearing aid fittings would result in many patients having a more accurately fitted hearing aid. As the majority of prescriptions could be adequately improved using NHS hearing aids, the effects on the hearing aid budget would be relatively small.

The effect of recurrent tonsillitis and tonsillectomy on growth in childhood

The aim of this study was to determine if children with recurrent tonsillitis are smaller than expected before tonsillectomy and if they have an altered height or weight gain 1 year post-operatively. All (204) children attending the hospital for tonsillectomy with or without adenoidectomy had their height and weight measured pre-operatively and 1 year after operation. The results of 2204 children in local schools were used as a control population. Analysis was by comparison of each population with the Tanner charts. This study suggests that our population of children listed for tonsillectomy were not lighter or smaller than expected before operation but that one year after tonsillectomy, there was an increase in their weight gain. The height gain was no different than expected after operation. Overweight seems to be a medium term complication of tonsillectomy. It may be necessary to redefine the indications for tonsillectomy in children who are already obese.

Idiopathic epistaxis, haemostasis and alcohol

Recent studies have suggested a link between antiplatelet medications and alcohol in the aetiology of acute adult epistaxis. The possibility that adult epistaxis may be associated with alcohol induced platelet dysfunction has not previously been investigated. This study evaluated primary haemostasis in 50 adult patients with idiopathic epistaxis. A detailed alcohol history was recorded and the Simplate bleeding time device was used to test haemostatic function. Forty-six per cent of patients were found to have an abnormality of primary haemostasis. Prolongation of the bleeding time was significantly associated with a history of alcohol use. The effect of alcohol on the bleeding time duration was significant (P < 0.001) even at low levels of intake of between 1 and 10 units per week. Although prevalent in the study group (42%) the use of non-steroidal anti-inflammatory drugs did not confer a significant additional risk of increased bleeding time. These findings support the importance of alcohol induced haemostatic abnormalities in the aetiology of adult epistaxis.

Changes in intensity discrimination following monaural long-term use of a hearing aid

Previous work has shown that a normally aided ear tested without the hearing aid is better able to identify speech-in-noise than the unaided ear at high sound levels, while performance for the unaided ear is superior at lower sound levels [S. Gatehouse, J. Acoust. Soc. Am. 86, 2103-6 (1989); J. Acoust. Soc. Am. 92, 1258-68 (1992)]. This effect was further explored using intensity discrimination for complex stimuli. Stimuli were half-octave bandpass-filtered tone complexes centered at 0.25 and 3 kHz. Four bilateral, symmetric hearing-impaired listeners with mean HL of 24 dB at 0.25 kHz, and 58 dB at 3 kHz were tested. Intensity discrimination was performed across the dynamic range of the listeners. At sound-pressure levels greater than 85 dB, the normally aided ear tested without the aid was more sensitive to changes in intensity than the unaided ear, whereas at lower levels, the converse occurred. This pattern was observed only for the 3-kHz center frequency, and not for the 0.25-kHz center frequency. Insertion gain measurements using the aids at normal volume showed an average of 20 dB gain at 3 kHz, and -2 dB gain at 0.25 kHz. The changes in intensity discrimination in the normally aided ear are consistent with the frequency-gain characteristics of the hearing aid, and suggest that a change in intensity coding occurred.

Speech discrimination in patients with Bell's palsy and a paralysed stapedius muscle

The contraction of the stapedius muscle results in a frequency dependant attenuation of sound through the middle ear. Idiopathic facial nerve paralysis (Bell's palsy) usually results in a paralysis of the stapedius muscle. This prospective study included 119 patients presenting with Bell's palsy over an 18-month period. After applying exclusion criteria, 80 patients with normal pure-tone audiograms underwent speech audiometry. This was performed on presentation and after recovery of the facial nerve palsy. Fifty-six patients (70%) with an absent stapedius reflex showed marked 'roll-over' from means of 98-49% on their speech audiogram. This resolved completely with recovery of the facial nerve palsy and return of the stapedial reflex. To determine whether this effect was due primarily to the paralysis of the stapedius muscle or to an associated polyneuropathy, a second study on six normal patients was done. These patients had both ears (12 in total) tested with speech filtered to simulate a paralysed stapedius muscle. This resulted in a mean 'roll-over' from 90.9 to 59.9%. The magnitude of this roll-over (31%) was only two-thirds of that seen in Bell's palsy patients (49%) with the difference between these means statistically significant (P < 0.05). This suggests that Bell's palsy, usually considered a mononeuropathy, involves certain of the auditory fibres of the eighth nerve and is a polyneuropathy. Stapedius function is important in speech discrimination at higher levels of sound intensity such as speech in noise and severing the stapedius tendon in stapes surgery may affect speech discrimination after successful surgery.

Estimation of the benefit of bone-anchored hearing aids

Implantable bone conduction hearing aids are a valuable alternative to conventional aids for those who cannot use a conventional air conduction aid or find it difficult to use because of an aural discharge, most commonly due to chronic otitis media. Previously reported series of the use of a bone-anchored hearing aid (BAHA) come from the originators of this device, and an independent report of their benefit and use, especially in previous air conduction aid users, would be of value. Twenty-three patients were evaluated at least 6 months after implantation of a BAHA. All 7 previous bone conduction aid users were delighted with their BAHA, reporting increased comfort and hearing benefit that was backed by audiometric evidence. Of the 16 individuals who previously used an air conduction aid, 11 (69%) were delighted users of their BAHA. Unfortunately, the other 5 (31%) reverted to solely using their air conduction aid. There was no obvious predictor as to how these individuals might have been identified prior to implantation. In particular, their pure tone thresholds, especially the bone conduction thresholds, were no different from those of the 11 BAHA users. However, in free field audiometry, the users gained superior benefit from their BAHA compared to their air conduction aid, whereas the nonusers did not. In conclusion, in all series to date, previous users of a conventional bone conduction aid have been delighted users of a BAHA and have gained superior audiometric benefit. This is not necessarily the case with previous air conduction aid users.(ABSTRACT TRUNCATED AT 250 WORDS)

Components and determinants of hearing aid benefit

This study investigates the measured and perceived disabilities and handicaps and associated auditory performance in 309 first-time hearing aid candidates. The results suggest that both disability and hearing aid benefit may be divided into separate components having particular and separate relationships to predictor variables in terms of both auditory and nonauditory characteristics. This division leads to a better understanding of the problems associated with a hearing impairment and their alleviation (or lack of) by provision of a hearing aid. In addition, the results support the development of more appropriate speech identification measures and suggest a potentially important role for measures of the temporal properties of the impaired auditory system.

Candidature for hearing aids: justification for the concept and a two-part audiometric criterion

A definition of hearing aid candidature is required for planning and other purposes. The number of candidates in the population actually receiving an adequate fitting would provide the major index of whether audiology services achieve their major public health goal. Many diverse factors determine the benefit that an individual receives from a hearing aid, and hence could in principle be included in some composite criterion for appropriate candidature reflecting the cost-effectiveness of patterns of provision. However, the complexity of universal capture, on those fitted with hearing aids, of data giving full auditory and demographic characteristics is beyond current routine NHS information systems. The most powerful known determinant established to date both of auditory disability and benefit is average hearing threshold level (HTL). Hearing threshold levels are hence both a necessary part of the fitting process and, given the data from the National Study of Hearing, a sufficient basis for computing population prevalences of hearing characteristics and service uptake in the major demographic strata. We report epidemiological data on consultation about problems with ears or hearing and uptake of hearing aids, which lead us to recommend a two-part candidature criterion on hearing threshold levels (0.5-4.0 kHz average): EITHER (a) better ear HTL > or = 35 dB OR (b) (15 dB < or = better ear HTL < 35 dB) WHEN worse ear HTL > or = 45 dB. The asymmetric component (b) may appear contentious, but is directly supported both by the epidemiological data and by further clinical data on benefit measured as performance on speech-in-noise tests. The proposed criterion is not over-liberal in clinical or related technological terms, but against the high prevalence of impairments in the population, the current provision and uptake of hearing aids in the UK still appear modest (about 3.3% in the population, and just under one-third of those qualifying by our criterion). Whatever the means of providing hearing aids, authorities charged with meeting the needs of their populations require such statistical indicators to know whether service delivery is appropriately geared. They should not use such an indicator as a basis of entitlement, as there are certainly individuals outside the criterion who receive benefit from their hearing aids. Equally, technological progress could expand the boundaries of candidature.

Role of perceptual acclimatization in the selection of frequency responses for hearing aids

Previous work concerning the late-onset auditory deprivation and/or acclimatization effect in adult hearing-aid users has suggested that the benefits of a particular frequency response from a hearing aid may not become apparent until material exposure to that frequency response has been achieved. The generality of that finding was tested further. A group of subjects who were established users (12 to 15 months) of a particular frequency response (limited at high frequencies by the system of provision) were re-prescribed with a theoretically advantageous frequency response according to the NAL prescription. Using a speech-in-noise test (word identification) and a sentence verification test, the benefits of the re-prescription were not (or at best only marginally) evident upon immediate testing but became statistically significant and of material clinical magnitude following experience with the represcription for 8 and 16 weeks. These results suggest that comparative selection regimes and research designs based upon little or no experience of the listening environment through the hearing aid are likely to seriously misrepresent the benefits available to the hearing-impaired listener.

Multiple primary malignant tumours in patients with head and neck cancer: the implications for follow-up

The pattern of second primary cancer occurrence in 518 Scottish patients with head and neck cancer was determined by a retrospective study. The overall incidence of second cancers was 9% but the true incidence increased steadily in the years following initial diagnosis to reach a maximum of 21% at 11 years. After 4 years of follow-up patients were more likely to die from a second primary cancer than from the effects of the initial tumour. The Scottish cohort differed from previously reported, overseas, study groups in having a high incidence of second primary cancers in sites outside the upper aerodigestive tract. This potential demographic difference suggests a need for local audit prior to design and implementation of screening protocols for second primary cancers.

The prevalence of middle ear disease in the adult British population

The UK National Study of Hearing set out to ascertain the prevalence of hearing impairments of various magnitudes, the prevalence of ear disease and the associated risk factors, and to estimate the percentage of individuals requiring some form of management. A stratified sample of 2708 British adults, aged 18-80 years, was chosen from a sample of 48,313 adults, randomly selected from the electoral roll, for a full otological and audiological assessment. This paper deals primarily with the middle ear results. Otoscopically, 2.6% of British adults had inactive and 1.5% had active chronic otitis media. This condition was more common in older individuals and in those in manual occupations. For this purpose, presumptive otosclerosis was defined as a conductive component to the impairment (average air bone gap over 0.5, 1 and 2 kHz of 15 dB or greater) and with an intact tympanic membrane. The population prevalence for presumptive otosclerosis was 2.1%, for healed OM 1.7% and for Eustachian tube dysfunction 0.9%. This prevalence of otosclerosis was higher in those over 40 years, but only in those with air bone gaps of 30 dB or greater were women more likely to have the condition than men, by a factor of three. At most, 20% of individuals with any of the above middle ear conditions will have had ear surgery.

Clinical pure-tone versus three-interval forced-choice thresholds: effects of hearing level and age

Hearing threshold levels were measured at 2 kHz using both a standard clinical procedure and a three-interval forced-choice procedure. The 240 subjects (aged 50-75 years) embraced both normal hearing and symmetrical sensorineural hearing impairment. The sample was carefully constructed to dissociate hearing threshold level from age, by oversampling the young impaired and the older normally hearing. The forced-choice threshold was found to be generally acuter than the clinical threshold. This was related to increasing severity of hearing loss at 1.7 dB per 10 dB HL and to age at 1.6 dB HL per 10 years. Hearing threshold accounted for 12% of the variance in the discrepancy between the two types of threshold, while age accounted for only 4% due to the narrow range used. After control for these thresholds and age, there were also significant associations with a self-estimate of hearing ability and with the neuroticism score from a personality questionnaire. When interpreting epidemiological findings, particularly in longitudinal studies, the separation between sensory and cognitive factors in threshold measures needs to be considered. The obtained discrepancies as a function of hearing level and age were applied to a statistical model for population prevalences for hearing impairment. The results suggested that the choice of method could have material effects on overall prevalence estimates and on the magnitude of the apparent age effect.

Costs of investigative protocols for cerebellopontine angle lesions in Scotland

Efficient use of resources demands evaluation of current practices. This paper presents a prospective evaluation of investigative protocols for cerebellopontine angle lesions. Commonly used protocols vary greatly in their clinical effectiveness and in their costs. The use of appropriate protocols would increase the number of tumours correctly diagnosed each year while also limiting the costs of investigation.

Clinical and financial audit of diagnostic protocols for lesions of the cerebellopontine angle

OBJECTIVE

To assess the diagnostic efficiency and costs of protocols used for investigating patients with suspected lesions of the cerebellopontine angle.

DESIGN

Prospective evaluation of tests of auditory brain stem responses and acoustic reflex thresholds, electronystagmography, and calorics. Positive test results were confirmed or refuted by high resolution computed tomography with intravenous enhancement.

SETTING

Single general otolaryngology clinic in a teaching hospital.

PATIENTS

270 consecutive patients with sensorineural hearing loss requiring investigation to exclude a lesion of the cerebellopontine angle.

MAIN OUTCOME MEASURES

Estimated costs of various diagnostic protocols and performance in detecting tumours of the cerebellopontine angle.

RESULTS

Protocols including tests of auditory brain stem responses and acoustic reflex thresholds as sifting tests before computed tomography were clinically acceptable and presented considerable savings over the use of computed tomography in all patients (74,000 pounds or 84,000 pounds v 122,000 pounds). The use of electronystagmography and calorics could not be justified on clinical or financial grounds.

CONCLUSIONS

Audiological tests of auditory brain stem responses and acoustic reflex thresholds followed by computed tomography constitute the most cost effective protocol for determining suspected lesions of the cerebellopontine angle.

IMPLICATIONS

The cost effectiveness of diagnostic protocols should be evaluated throughout the health service.

Reliability of patient choice between hearing aid systems

Various hearing aid provision strategies have been suggested but it is important to compare patient benefit from these, not only in the laboratory, but in everyday life. The latter can only be assessed by patient report. The false positive report rate of a difference between aids and the reproducibility of patient choice of aids was assessed in two groups of patients. The first received the same system on two occasions and were asked to report if they had any preference. The second group received two different systems on two occasions and the reproducibility of any preference was assessed. Of the 22 patients who were given the same hearing aid system on each visit, eight (36%) reported no differences, 10 (45%) a little and four (18%) a moderate or large difference between them when, in fact, there was none. Of the 34 patients who were asked to compare two acoustically different aids, 32 chose an aid on both occasions but only 22 (65%) chose the same aid, of whom 11 (32%) reported a moderate or large difference on both occasions. If reports of a little difference between aids are discounted and only moderate or large differences are accepted, it is concluded that the false positive report rate of a difference is approximately 20%. In addition, when patients are being asked to compare two NHS hearing aid systems, the rules of chance, order effect and reproducibility of patient choice have all to be controlled for, before decisions regarding patient preference can be made.

The Glasgow Benefit Plot: a new method for reporting benefits from middle ear surgery

Conventionally, the results of middle ear surgery are reported in terms of postoperative closure of the air-bone gap or the improvement in air-conduction thresholds. While these are relevant in that they assess the technical success of the procedure and the lessening of monaural disability, they do not necessarily assess whether the patient has benefited. This is determined by many factors, not least of which is the hearing in the nonoperated ear. In this paper, we suggest that preoperative and postoperative plots of the air-conduction thresholds in both ears be used as an additional method of presenting the results. First, the proportion of patients that fall into each of three main preoperative impairment groups are identified. This is important, as the potential benefits from surgery are not the same in each group. Thereafter, the percentages of patients that achieve various postoperative hearing categories can be calculated, allowing surgeons to audit their results and make comparisons between series.

Whole blood viscosity and red cell filterability as factors in sensorineural hearing impairment in the elderly

Deficiencies in blood supply can lead to impairments in cochlear function. We have reported significant associations of both measures of whole blood viscosity and derived measures of red cell rigidity with hearing threshold levels in individuals with sensorineural hearing impairments. This paper describes direct measures of red cell filterability in a group balanced across the variables of hearing threshold level and age to facilitate dissociation of the effects of factors correlated with age. After controlling for effects of age, sex and social class, there were strong correlations between whole blood viscosity at high shear rate and hearing threshold levels at 250, 500, and 1,000 and 2,000 Hz. At 4,000 and 8,000 Hz, hearing threshold level was related to red cell filterability. When the data are divided into subgroups by age, the younger age group exhibited a pattern similar to the overall one, but in the older age group the effect of red cell filterability was more apparent, extending down to 1,000 Hz. The data support a strong association between aspects of blood rheology and sensorineural hearing impairment, but in a more complex manner than suggested by previous studies. They imply that there are two processes associated with sensorineural hearing impairment, one of which can be considered as due to bulk rheological properties, while the other appears more related to the properties of individual red cells. The bulk properties are more important at lower frequencies, while the cellular properties are more influential at higher frequencies.

The contribution of central auditory factors to auditory disability

Auditory disability increases with both hearing threshold level and age. It is often suggested that some or most of the age effect in auditory disability is underpinned by deficits in central auditory function. A sample of 240 individuals aged between 50 and 75 years was examined to provide a balance across the major variables of hearing level and age. The central auditory indices investigated were: the binaural masking difference, the effects of dichotic competition on the staggered spondaic word tests, the binaural advantage for dichotically presented words, the binaural advantage for dichotically presented sentences, the effect of increasing the rate of presentation of speech, and the effect of nonsense as opposed to sensible sentences. In addition, the non-auditory variables of verbal and non-verbal IQ and the peripheral auditory factors of frequency and temporal resolution were assessed. Auditory disability was assessed using a performance index derived from a sentence identification-in-noise procedure and a procedure containing sense or nonsense sentences. Aspects of self-reported disability were determined using the MRC Institute of Hearing Research's Hearing Disability Questionnaire and the American Hearing Performance Inventory. There were significant correlations between the derived central variables and measured disability after control for hearing threshold levels and age. Central variables were correlated with self-reported disability for only the specific sub-score reflecting disability in localisation. On a multiple regression, the central variables explained 11.1% of the variance in performance index of disability above the 21.1% explained by hearing threshold levels and age.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors that influence the benefit from amplification in the elderly

Many factors have been proposed as potential determinants of the benefit that an individual receives from wearing a hearing aid. In this study, to quantify their relative importance, 54 individuals with symmetrical sensorineural hearing impairment were presented with and without simulated hearing aid characteristics on two measures of disability that were based on identifying words in sentences. Benefit was defined as the difference between the percentage of correct scores with and without the aid characteristics switched into the audio circuit. The factors investigated were age, various peripheral auditory functions, central auditory factors and non-auditory factors such as IQ and personality. Initial correlations suggested a strong relationship between the benefits of amplification and four types of variable: hearing threshold level, frequency resolution, aspects of central function, and the discrepancy in auditory threshold between two methods--a robust psychometric three alternative forced-choice procedure and a conventional audiometric procedure. When the effects of hearing threshold level were partialled out, there remained strong correlations with frequency resolution, co-modulation masking release, and the threshold discrepancy measure. Frequency resolution and threshold discrepancy accounted for a further 21.1% of the variance over the 26.5% of the variance accounted for by hearing threshold level. There were no correlations in this sample of benefit with age, once other aspects had been accounted for. The results indicate a strong role for frequency resolution in the potential benefits from amplification, in addition to central factors such as co-modulation masking release.(ABSTRACT TRUNCATED AT 250 WORDS)

The output characteristics of an implanted bone conduction prosthesis

So far, the published guidelines for patient selection for the Audiant implanted bone conduction device have been derived from clinical trial rather than experimental study. Theoretical considerations suggest that the guidelines should be frequency specific; the need for this was investigated in a laboratory study. Two independent measures of the maximum output of the Audiant device using both the body-worn and ear-level amplifiers have been performed on two subjects. These lead to maximum output figures for the device ranging from 15 dB HL at 250 Hz to 60 dB HL at 6000 Hz for the body-worn amplifier, and from 6 dB HL at 250 Hz to 42 dB HL at 6000 Hz for the ear-level amplifier. These results suggest that the ear-level amplifier is suitable only for candidates with essentially normal bone conduction thresholds at frequencies of 1000 Hz and below.

Fundamental issues in self-assessment of hearing

The history of self-assessment for hearing is reviewed from its beginning use in the 1930s to its emerging importance in the 1980s. It is presented as a more systematic method for interviewing the patient, and although it does not always agree with pure-tone findings, it should be recognized as a useful assessment method to be used in combination with other measures of hearing. The uses for self-assessment, psychometric concerns, issues in the definition of hearing domains (disorder, impairment, handicap, disability), and new frontiers also are discussed in this overview article.

Determinants of self-reported disability in older subjects

The effects of hearing threshold levels, age, personality, and IQ on indices of self-reported disability/handicap derived from the Hearing Performance Inventory and the Institute of Hearing Research Hearing Disability Questionnaire have been investigated in a sample of 240 individuals with bilateral, symmetric sensorineural hearing, which was efficiently balanced across hearing threshold level and age. The results show significant effects of age, IQ, and, in particular, personality on many aspects of reported disability/handicap, with different relative contributions for females and males. It is possible to account for between 42 and 50% of the variance in most of the disability/handicap indices. Around 5% is accounted for by age and between 12 and 22% by aspects of personality. These findings suggest that the effects of age, IQ, and personality should be considered and incorporated into any practical application using self-assessment instruments.

Factors influencing consultation for management of hearing disability

The aim of this study was to compare individuals referred to an Audiology Clinic (consulters) with hearing-impaired individuals in the population who have never sought advice (non-consulters) in order to identify factors which lead some individuals with hearing problems to seek management while others with apparently similar impairments do not seek advice. Two hundred and sixty nine consulters referred to the Audiology Clinic at Glasgow Royal Infirmary were compared with 289 individuals identified in the MRC National Study of Hearing who had never sought advice as an adult about hearing problems. Age, sex, socio-economic group and better-ear hearing threshold were controlled for in all analyses. Consulters were found to have more asymmetrical hearing than non-consulters. They had greater measured disability and reported more disability when their measured disability and impairment were controlled for. They were also more handicapped when impairment and disability were controlled for.

The Chief Scientist reports ... hearing research at the Medical Research Council Institute of Hearing Research (Scottish Section)

In addition to conducting research with the Section's own resources from the MRC and the Scottish Home and Health Department, the Section stimulates collaborative clinical research with the University and Health Service Departments. This work would be unlikely to take place without the existence of the Scottish Section of the MRC Institute of Hearing Research. Its presence has contributed to the continuing recognition of the Royal Infirmary Departments as an attractive centre for postgraduate training by both British and overseas graduates, leading in time to a substantial body of clinical research in ENT. This close interlinking between a research unit and an academic otolaryngology department is most unusual in the UK and encourages a programme which contains elements of readily applicable clinical research. Clinical and scientific environments are mutually stimulating, so the Section also incorporates in Glasgow some more fundamental laboratory-based studies also, which aim to investigate underlying issues in the diagnosis and management of otological conditions.

Response times to speech stimuli as measures of benefit from amplification

The benefits of management of hearing disability, in particular by provision of a hearing aid, are traditionally assessed by the percentage improvement in performance on a speech identification task. To provide precise and stable results, such procedures require more time than is available in most clinical settings. In any stressed performance, e.g. an impaired individual trying to listen in noise, there is a trading relationship between accuracy and effort (the cost at which accuracy is achieved). If the control of performance naturally spends effort to stabilize high performance, then benefit from amplification may essentially comprise and be measurable as reduction in effort rather than improvement in accuracy. Certainly complaints of hearing disability emphasize fatigue from careful listening. Hence a hearing aid may not only enable hearing impaired persons to hear more of speech but may enable them to hear it more easily, thus reflecting a second dimension to disability and benefit. Ease of listening was investigated using auditory response times to speech stimuli of two levels of structure: single words and sentences. The speech material was presented to 44 experienced hearing aid users (mild to moderate sensorineural hearing impairment). The speech was presented both unaided and aided at presentation levels of 60, 70 and 80 dB SPL and signal-to-noise ratios of quiet and + 5 dB. Response times were taken to the tokens within each list that were correctly identified. Benefit is defined as the decrease in response time from the unaided to the aided condition.(ABSTRACT TRUNCATED AT 250 WORDS)

A pseudo free-field measure of auditory disability

Conventional measures of auditory disability via speech identification scores are usually monaural, or occasionally, diotic. Circumstances of everyday listening usually contain stereophonic (dichotic) cues, whilst such listening situations can be tested in a free field environment they are difficult to standardize and calibrate. A procedure has been developed by recording the signals from two Zwislocki couplers in a KEMAR mannikin to produce a headphone-presented set of speech material containing the important dichotic cues present in free field listening. This enables readily calibrated and experimentally controllable conditions to be set up to measure aspects of auditory disability and, for example, its alleviation via amplification. Two examples of the use of the test are provided: (i) the assessment of the benefits of the presence of stereophonic cues on speech identification in both the real free field and simulated conditions, and (ii) the benefits of monaural and binaural provision of amplification of hearing impaired people in directional listening situations.