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Biomedical subjects

G G Browning

Publications and source records attributed to G G Browning.

At least 19 recordsLinked to original sources
PubMed1992

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.

Adult↗
PubMed1991

Randomized, cross over study to assess patient preference for an acoustically modified hearing aid system.

It seems reasonable to postulate that if a patient has a hearing impairment at particular frequencies, selective amplification at those frequencies would be an advantage. Attempts have been made in the laboratory to show that when this is done scores on various audiometric tasks will improve. Whether such laboratory benefit will be preferred by patients in their daily life is another matter. Despite a lack of knowledge on this subject, modifications are frequently made to a hearing aid system in the expectation that this will improve auditory performance and hence be preferred by the patient. The most common modifications made to an ear level aid in the British National Health Service are adjusting the tone control and venting the ear mould with the aim of emphasizing the higher frequencies. A randomized crossover study was carried out in 83 first time hearing aid users with a mild to moderate hearing impairment to assess whether a hearing aid at the 'H' tone setting and with a 2 mm vented mould would be preferred by those with a more marked high frequency impairment. BE series aids were used so that any findings could be directly translated to NHS practice. No consistent preference for the modified system was identified when patients were subgrouped according to the overall slope (0.5 to 4 kHz) of their audiogram. However, when the slope between 0.25 and 1 kHz, which corresponds to the real ear effect of these modifications, was analyzed patients with a slope at these frequencies preferred the high-tone emphasis system (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Characterization of severely and profoundly hearing impaired adults attending an audiology clinic.

Despite the fact that around 12 per cent of adult patients attending an audiology department will be severely hearing impaired (pure tone averages of 0.5, 1, 2 and 4 kHz of 70 dB HL or worse in the better hearing ear), their clinical and audiometric characteristics have not been well documented. These characteristics were collected prospectively in 132 adult patients attending a Severe Impairment Clinic, set up to manage their specific problems. The inability to provide sufficient masking makes audiometric assessment of the severity of the impairment uncertain in the poorer hearing ear in 52 per cent of these patients. In addition, the limited bone conduction output makes it almost invariably impossible to assess the masked bone conduction thresholds and hence the air-bone gap in the poorer ear. Hence, accurate characterization is only practical of the better hearing ear in such patients. In 67 per cent of the better hearing ears, there was a mixed hearing impairment, the air-bone gap being 20 dB or greater. The aetiology of the conductive component was almost equally otosclerosis and chronic otitis media. In only 19 per cent was the impairment of a pure sensorineural type, broken down as 6 per cent congenitally acquired, 5 per cent due to meningitis and 9 per cent being adult in onset. In the remaining 14 per cent of patients the type of impairment could not be classified as the bone conductive thresholds were off scale. Having had experience of managing these patients at a special clinic and knowing the workload involved, it is argued that consideration be given to setting up such clinics in most departments.

Adolescent↗
PubMed1991

Can meta-analysis help uncertainty in surgery for otitis media in children.

While otitis media is perhaps the most common disease of childhood that receives medical attention, there is little agreement concerning the efficacy of the medical and surgical therapies employed to try to alleviate its symptoms or hasten its natural resolution. Because various surgeries including adenoidectomy, myringotomy, and insertion of tympanostomy tubes are frequently involved in the treatment of otitis media with effusion (OME), it is likely the most expensive condition being managed in national terms. In an attempt to elucidate the most appropriate management of this condition, a meta-analysis was attempted to the 12 randomized control trials of surgical treatments for OME in children, published between 1966 and 1990. Heterogeneity both in the populations and comparisons studied and in the outcomes presented made meta-analysis an inappropriate method for clarifying this area of clinical uncertainty. Important elements in the design of randomized control trials that should be included in future studies of treatment for OME are therefore discussed.

Adenoidectomy↗
PubMed1991

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.

Adult↗
PubMed1991

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.

Aged↗
PubMed1990

Risks of developing an otogenic intracranial abscess.

One-and-a-half per cent of adults have active chronic otitis media and its management to prevent complications is a considerable workload. The risks of developing these complications is relatively unknown but because of its mortality, intracranial abscess is the most relevant. A 10-year review of all otogenic intracranial absesses in Scotland was carried out. A 15 per cent allowance was made for missing records. The annual risk in an adult with active chronic otitis media of developing an abscess is about one in 10,000 but its development is three times more likely in males. This risk might appear low but the lifetime expectancy of an individual aged 30 years with active chronic otitis media developing an abscess is one in 200. However, as yet, there is no evidence that surgery reduces this risk. Unfortunately, because of the duration of follow-up needed and the size of the sample required, scientific evidence would be difficult to obtain. However, 5 per cent of abscesses currently occur in the immediate post-operative period following mastoid surgery.

Adolescent↗
PubMed1990

The British experience of an implantable, subcutaneous bone conduction hearing aid (Xomed Audiant).

Implantable bone conduction aids are potentially an important advance for those with a conductive hearing impairment. One system (Xomed Audiant bone conductor), which uses electromagnetic induction to vibrate a subcutaneous implanted skull magnet, has now been implanted in sufficient patients in the United Kingdom, for enough time, for its indications to be evaluated. Seventeen of the total of 18 patients that have been implanted, satisfied the average threshold criterion for suitability for implantation (average bone conduction over 0.5, 1 and 2 kHz of 25 dB HL or better) yet only 10 of the 17 (59 per cent) currently use their Audiant aid. This was not because of technical reasons but was mainly influenced by the previous type of amplification. Current usage of a body level processor was 100 per cent) (6 of 6) in those that previously could only use a conventional bone conduction aid because of bilateral congenital or acquired atresia of their external auditory canals. In comparison, usage was only 36 per cent (4 of 11) in those that could potentially use a conventional ear level aid albeit with problems such as the discharge from active chronic otitis media. This relative non-use was considered due to a lack of power of the ear level processor and the general unwillingness of patients to change from an ear level to a body level device.

Adolescent↗
PubMed1990

Hearing disability and hearing aid benefit related to type of hearing impairment.

This study was designed to investigate whether patients with a conductive hearing impairment derive more benefit from the provision of a hearing aid than comparable individuals with a sensorineural hearing impairment. A secondary aim was to assess the relative hearing disability of those with each type of impairment. Twenty-eight patients with a bilateral, symmetrical conductive impairment were selected. They were matched for age, sex and speech frequency average to individuals with a bilateral, symmetrical sensorineural hearing impairment. Each patient performed free-field audio and audio-visual tests in noise, both with and without a hearing aid, during which the non-test ear was acoustically occluded. When unaided, individuals with a conductive impairment were more disabled than those with a sensorineural impairment. On the other hand, those with a conductive impairment derived more benefit from an aid than those with a sensorineural impairment.

Adult↗
PubMed1990

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.

Adult↗
PubMed1989

Clinical role of informal tests of hearing.

Clinical tests of hearing are regularly used in adults but their role, now that pure-tone audiometry is almost universally available, has not been evaluated by modern methods of analysis including sensitivity and specificity. Free-field voice testing was carried out in 101 patients and the Rinne tuning-fork test in a different group of 127 patients prior to clinical or audiometric evaluation. The results were subsequently compared to air and bone conduction pure-tone thresholds assessed using rigorous standards. Depending on the audiometric definition as to what constitutes a hearing impairment, the sensitivity of free-field voice testing to identify such an impairment because of an inability to hear a whispered voice at two feet (60 cm.) was 86 per cent or better with the specificity being in the region of 90 per cent. In the Rinne test the 256 Hz fork was superior to the 512 Hz fork (p less than 0.05) and the loudness comparison method superior to the threshold decay method (p less than 0.01) in detecting an air-bone gap. Combining the responses to the two forks did not improve the results. The Rinne test with the 256 Hz fork will identify correctly 48 per cent of individuals with a 15 dB, 69 per cent with a 20 dB, 87 per cent with a 25 dB, and 95 per cent with a 30 dB conductive impairment. In all instances the specificity is greater than 90 per cent.

Audiometry, Pure-Tone↗
PubMed1989

Open-cavity mastoid surgery: its effect on the acoustics of the external ear canal.

Temporal bone studies have demonstrated that a modified radical mastoidectomy changes the resonant characteristics of the external auditory canal, but the effect has not been reported in patients. In 12 patients, performing open-cavity mastoid surgery for cholesteatoma changed the mean peak resonant frequency of the external ear canal from 2.5 to 2.2 kHz (p less than 0.02). This is in comparison with creating a modified radical mastoid cavity in 6 temporal bones which changed the mean peak resonant frequency of the external ear canal from 3.9 to 1.9 kHz. It is concluded that open-cavity mastoid surgery in patients changes the acoustics of the external ear canal less than in temporal bone studies.

Acoustics↗
PubMed1989

Eustachian tube function following adenoidectomy: an evaluation by sniffing.

Recent investigations have demonstrated an association between sniff-induced negative middle ear pressure and otitis media with effusion. This is taken as evidence of Eustachian tube malfunction. Adenoidectomy is frequently performed as part of the surgical management for otitis media with effusion, but whether this affects Eustachian tube function is uncertain. The aim of this study was to investigate the hypothesis that if adenoidectomy improved Eustachian tube function, children who had undergone adenoidectomy would show less tendency to generate a high negative intratympanic pressure by sniffing. Eustachian tube function was studied actively in 40 children with otitis media with effusion. Twenty children, selected at random, underwent adenoidectomy and all 40 had a unilateral grommet inserted. Eighty-five percent of the children could create a negative middle ear pressure by sniffing, but there was no difference in the number of 'sniff + ve' children between the adenoidectomy and control groups (P greater than 0.5), or in the magnitude of the negative pressure induced. It is concluded that a high percentage of children with otitis media with effusion are capable of inducing a negative middle ear pressure by sniffing, but this parameter of Eustachian tube function is not affected by adenoidectomy.

Adenoidectomy↗
PubMed1989

The Bing test in the detection of conductive hearing impairment.

The Bing test is based on the principle that occlusion of the external auditory meatus improves the perception of bone-conducted sounds unless there is a conductive hearing impairment. However, its sensitivity and specificity have not been reported. Tuning-fork and audiometric Bing tests were carried out on 126 patients with otological symptoms prior to any otological history or examination. Test results were compared with the pure tone air-bone gaps. The specificity and sensitivity of each test method was estimated. The tuning-fork Bing test was less sensitive than the audiometric Bing test, but had greater specificity. However, the Rinne test with the 256 Hz fork and the loudness comparison method was more sensitive than the Bing tuning-fork test, and had similar specificity. The Rinne is therefore the better test for clinical use.

Adult↗
PubMed1989

Hearing in chronic suppurative otitis media.

In individuals with chronic otitis media, mixed hearing impairments are common but it is unclear whether the raised bone conduction thresholds are a reflection of the pathologic process affecting the inner ear or a combination of the high prevalence of sensorineural hearing impairments in the population along with the artificial elevation of bone conduction thresholds associated with a conductive defect. A total of 395 ears with chronic otitis media but without cholesteatoma were studied. In them, once the artificial elevation (Carhart effect) of the bone conduction thresholds, which occurs whenever there is an abnormality of the sound conduction mechanism, had been taken into account, there was no difference in the bone conduction thresholds compared with those in 920 control ears. In addition, in 100 instances, the contralateral ear was normal and there was no difference in the bone conduction thresholds between the diseased and the normal ears. Raised bone conduction thresholds in chronic otitis media are considerably likely to reflect both the Carhart effect and the high prevalence of sensorineural impairments, rather than disease damage to the inner ear.

Auditory Threshold↗