Biomedical subjects

P J D Dawes

Publications and source records attributed to P J D Dawes.

6 recordsLinked to original sources

PubMed2006

Malleus-stapes assembly: experience with two prostheses.

Tympanoplasty is often a necessary part of middle-ear surgery, the most common defect being that between an intact, mobile stapes and the malleus handle. The most readily available tissue is the patient's incus, reshaped to bridge the space between an intact stapes and the malleus. When the incus cannot be used, the hydroxyapatite Wehrs incus prosthesis can be used as an alternative.Twenty-six patients had an autograft incus ossiculoplasty and 20 patients underwent modified Wehrs incus prosthesis ossiculoplasty. The average post-operative air-bone gaps (ABGs) were 16.2 dB hearing loss (dBHL) and 17.2 dBHL, respectively. Air-bone gap closure to within 15 dBHL was achieved for 48 per cent of incus autografts and for 57 per cent of Wehrs prostheses, and to within 20 dBHL for 77 per cent and 62 per cent, respectively. Over four years follow up, the reconstruction was stable for each group, the ABGs being 17.7 dBHL and 17.1 dBHL, respectively.

Chronic Disease↗

PubMed2006

How we do it: tympanoplasty: are different three- and four-frequency averages comparable?

The results of tympanoplasty may be reported in a variety of ways. Pure-tone audiometry underpins reporting, yet there is no constancy in the pure-tone threshold average used. We examine the relationship between the 0.5, 1, 2 kHz, 0.5, 1, 2, 3 kHz and 0.5, 1, 2, 4 kHz pure-tone audiometry averages. Using audiometric data collected for 77 patients, we have compared hearing threshold using three different frequency averages derived from pure-tone audiometry. The 0.5, 1, 2 kHz, 0.5, 1, 2, 3 kHz and 0.5, 1, 2, 4 kHz three- and four-frequency averages are significantly different, this difference being primarily determined by the changes in the 4-kHz threshold. Using an average including 4 kHz results in 8% few patients achieving an ABG closure to within either 10 dB or 20 dB. When comparing surgical results with others, surgeons should use reports employing comparable audiometric measures of analysis.

Adolescent↗

PubMed2005

How we do it: modified Wehrs incus ossiculoplasty.

Keypoints * Ossiculoplasty is commonly performed as part of tympanoplasty. Hydroxyapatite is a favoured material for ossicular protheses. * A modification to the Wehrs incus prosthesis is described. * Twenty-one procedures were performed on 20 patients and the results are reported. * On average there was a 4-5 dB closure of the air-bone gap (ABG), with patients having a hearing gain procedure averaging 11 dB closure. Air-bone gap closure to <or=20 dB was achieved between 78% (0.5, 1, 2 kHz average) and 60% (0.5, 1, 2, 4 kHz average) of patients and this was stable during long-term follow-up of the ABG. * Wehrs incus prosthesis ossiculoplasty provides a reliable result following ossiculoplasty when autograft incus is not available.

Adolescent↗

PubMed2004

Tympanoplasty - reporting hearing results and 'hearing objective'.

When reporting the results of tympanoplasty, the postoperative air-bone gap (ABG) presented in 10 dB bins, ABG closure and air conduction threshold gain are commonly reported indicators of tympanoplasty outcome. When tympanoplasty is performed, the reconstruction aims either to improve hearing threshold or to maintain satisfactory thresholds, that is, the surgical intention is either for 'hearing gain' or for 'hearing preservation'. This review of the early results of tympanoplasty examines whether classifying surgery as either for hearing gain or for hearing preservation influences the reported results. Closure of the ABG to within 20 dB was achieved in 72-94% of cases, the average postoperative ABG was between 13.1 and 17.1 dB with the postoperative air conduction threshold being between 27.4 and 33.5 dB. These figures were similar for both hearing preservation and hearing gain procedures. However air conduction threshold gain was significantly greater for the 'hearing gain' group (17 dB versus 0 dB) and was reduced to 8 dB by combining the two groups. Overall, indicating whether surgery attempted hearing preservation or hearing gain did not significantly alter the parameters used for reporting tympanoplasty outcome.

Adolescent↗

PubMed2004

The smell map: commonality of odour perception confirmed.

We have examined the repeatability of a perceptual space, or smell map, initially developed in a sample of 20 people. A total of 110 normosmic people performed similarity ratings for pairs of the 11 commonly encountered odours used in the previous study. Multidimensional scaling was again used to analyse the relationships between odours. Some individual plots and an archetype, generated using the data from all participants, produced results similar to the previous study, confirming the ability to obtain reproducible results using a different tester and different participants. Exploration of the source space, that is, the spatial distribution of the individual plots relative to each other, suggests that the current model explains about 50% of the variation between subjects for the two-dimensional solution and 57% for the three-dimensional solution.

Adolescent↗

PubMed2003

Myringostapediopexy: surgical expectation.

Myringostapediopexy may occur as a result of incus erosion with medialization of the tympanic membrane and is recognized as often producing serviceable hearing. The technique may be used as part of tympanoplasty following either canal wall up or canal wall down surgery for chronic otitis media. The use of this type of reconstruction is influenced by the anatomy of the ear after disease excision. This review of the hearing levels associated with myringostapediopexy shows that there is a similar range of hearing level both for naturally formed as well as surgically fashioned myringostapediopexy. For both 'naturally formed' and following canal wall up surgery about 80 per cent of patients will have an air-bone gap of 20 dB or less compared to 60 per cent of those who undergo canal wall down surgery.

Adolescent↗