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Biomedical subjects

T Lau

Publications and source records attributed to T Lau.

At least 37 records · Page 2Linked to original sources
PubMed1989

Late results of surgery in different cholesteatoma types.

Our series of 740 cholesteatomas, operated during the period 1969 to 1980, were seen at follow-up several times with a median observation period of 9.2 years (range 3-21 years). There were; 273 attic cholesteatomas with retraction (perforation) of Shrapnell's membrane; 271 sinus cholesteatomas with superioposterior retraction (perforation) of pars tensa, and 196 tensa retraction cholesteatomas extending from a retraction of the whole pars tensa. The late results were analyzed for each type separately, and compared. The recurrence rate was lowest (6.6%) in attic cholesteatoma and highest (13.3%) in tensa retraction cholesteatoma. In all three types no residual cholesteatomas were detected after the 4th postoperative year, whereas recurrent cholesteatomas occurred up to 10 years after surgery. The reoperation rate was lowest (15%) in attic cholesteatoma and almost the same (21%) in sinus and tensa retraction cholesteatoma. The hearing results were best in attic cholesteatoma and poorest in tensa retraction cholesteatoma. It is concluded that cholesteatoma surgery should be individualized and that both the canal wall up and canal wall down methods have their place in cholesteatoma surgery.

Adolescent↗
PubMed1989

Stability of tympanoplasty in children.

The results of tympanoplasty performed for noncholesteatomatous chronic otitis in children aged 2 to 14 years are described. The authors report that the stability of hearing was excellent; they found hearing to be equally good in young children and in older children. Tympanic membrane perforation can be closed at any age. There is no age limit below which perforation should not be closed.

Adolescent↗
PubMed1988

Treatment of sinus cholesteatoma. Long-term results and recurrence rate.

We classified cholesteatomas as attic cholesteatoma, developing from Shrapnell's membrane; tensa cholesteatoma, originating in pars tensa, which is subdivided into tensa retraction cholesteatoma involving the entire pars tensa, and sinus cholesteatomas, developing from a posterosuperior retraction (perforation). From 1964 to 1980, one-stage operations were carried out on 271 ears with sinus cholesteatomas. Follow-up included 90% of the patients, and the median observation time was 9.75 years. The recurrence rate was 10%. The recurrence rate was found to be independent of the mastoidectomy type employed. The best hearing results were obtained in ears with intact ossicular chain. We conclude that, wherever possible, sinus cholesteatoma should be removed through the auditory canal without mastoidectomy just as an intact ossicular chain should be preserved. "Canal wall up" and "canal wall down" appear to be equally valuable mastoidectomy types, and both methods must be employed to obtain optimum results.

Acoustic Impedance Tests↗
PubMed1988

Conservative therapy for melanoma of the vulva.

Recent cooperative studies have demonstrated that less radical local resection of cutaneous melanomas is equally effective as a traditional radical approach. A retrospective review of vulvar melanoma was undertaken to determine if mode of therapy affected recurrence. Survival correlated independently with depth of invasion and age (p = 0.05 and p less than 0.02, respectively). In the comparison of radical vulvectomy with local excision, no patient differences in age or histopathologic variables were determined (nodal disease status, histology, mitotic count, lymphocytic infiltration, or ulceration). Radical vulvectomy did not improve survival over local therapy (p greater than 0.2). Six of eight patients whose melanoma had less than 2 mm of invasion treated with local therapy are disease free after a median of 127 months (range 6 to 300 months). For local excision, recurrences were more frequent when margins were less than 2 cm, but this was not statistically significant in this small sample. Although the current series is small and retrospective, its findings suggest that treatment recommendations of large cutaneous nonvulvar melanoma studies are applicable to vulvar melanoma. A prospective randomized study of radical versus conservative surgery for vulvar melanoma will be necessary to confirm these treatment recommendations.

Adult↗
PubMed1988

Attic cholesteatoma. Recurrence rate related to observation time.

Two hundred twenty-four ears with attic cholesteatomas, subjected to one-stage surgery between 1965 and 1978, were reevaluated several times, most recently in 1980/81 at a median observation time of 8 years (range, 3 to 16 years) and in 1985/86 at a median observation time of 11 years (range, 3 to 21 years). The recurrence rate was related to length of observation time. Up to and including the follow-up examination in 1980, the rate of residual cholesteatoma in the tympanic cavity was 1.3% and 0.9% in the attic. The incidence of recurrent cholesteatoma in the attic or the cavity was 1.8%. The total recurrence rate was 4.0%. At follow-up in 1985/86, the total recurrence rate had increased to 6.3%, comprising residual cholesteatoma in the tympanic cavity in 1.8% and in the attic in 0.9% and recurrent cholesteatoma in 3.6%. A total of 133 patients had a modified canal wall up mastoidectomy, whereas 91 patients had canal wall down mastoidectomy with obliteration. With regard to the total results of surgery, no significant differences could be demonstrated between the two methods, and we conclude that canal wall up mastoidectomy can be performed in one stage.

Cholesteatoma↗
PubMed1987

Removal of observer variability from the determination of the volume of isoflow.

The initial attractiveness of the volume of isoflow (VisoV) as an index of early small airways dysfunction has faded, perhaps because of VisoV's high variability, a significant part of which is contributed by the observer. We suggest here that the observer variability can be removed by filtering the flow data in the reciprocal volume domain, by using a modified foreign gas mixture in which some of the helium is replaced by neon, and by reading VisoV from a plot of density dependence vs. lung inflation. Support for these suggestions is drawn from both model simulations and experiments. Model simulations suggested that VisoV would be increased by the substitution of neon for some of the helium in the usual helium-oxygen (Helox) mixture. This was confirmed in tests on matched groups of normal and asymptomatic asthmatic children. The inclusion of 20% neon (Heneox20) was found to reduce the coefficient of variation in the mean value of VisoV in both groups of subjects. An interesting result of this test was that VisoV using Heneox20 was significantly higher in the asthmatic group than in the normal group, whereas VisoV using Helox was not. The results for density dependence (DD) between the 2 groups were not significantly different using Heneox20 but were using Helox. Plots of DD (derived from heavily filtered flow curves) vs. lung inflation showed an unambiguous value for VisoV.

Adolescent↗
PubMed1987

The effect of total body irradiation and bone marrow transplantation during childhood and adolescence on growth and endocrine function.

Seventeen children (11 M, 6 F) with acute leukaemia and myeloproliferative disorders were investigated for growth and endocrine dysfunction. All had undergone bone marrow transplantation prepared with cyclophosphamide and single fraction total body irradiation (900-1000 cGy) between 1.5 and 3.8 (mean 2.2) years previously. The majority of children exhibited growth failure, which was of multiple aetiology. Ten patients, of whom eight had had previous prophylactic cranial irradiation, had evidence of growth hormone deficiency based on the reduced growth hormone response to insulin induced hypoglycaemia. Three patients had evidence of hypothalamic damage as shown by their growth hormone response to 200 micrograms GHRH (1-29) NH2 intravenously. Gonadal failure was common, assessed clinically, and biochemically by basal gonadotrophin and sex steroid concentrations. All four girls of adolescent age (10.6-14.1 years) had ovarian failure requiring sex steroid replacement. Of the eight boys of adolescent age (12.3-18.3 years), two had testicular failure requiring sex steroid supplements. Both of these had had previous testicular irradiation. Five others had compensated gonadal failure, and one had normal Leydig cell function. Abnormalities of the TSH response to TRH occurred in 10 patients but only three had overt hypothyroidism. Unlike growth hormone deficiency, gonadal and thyroid dysfunction showed no correlation with previous cranial radiotherapy.

Adolescent↗
PubMed1986

Revision tympanoplasty.

The terms 'planned two-stage operations', 'planned second-look operations', 'previous surgery', and 'revision surgery' are discussed on the basis of our series of 2,303 ears operated upon from January 1965 to December 1980. We have not performed any planned two-stage operations. All operations prior to the first operation in our department are denoted 'previous surgery'. 'Revision surgery' denotes all reoperations performed either in this department or elsewhere during the observation period until the end of 1984, and the revision rate is analysed in patients with different pathological conditions. 'Revision surgery' was performed in 15.6 percent of 740 ears with cholesteatoma (in 13.9 per cent once, in 1.6 per cent twice, and in 0.1 per cent three times), and 'previous surgery' in 3 per cent. Among 229 ears with chronic granulating otitis, revision surgery had been performed in 12.2 per cent up to December 1982. By December 1984, this figure had risen to 16.1 per cent. 'Previous surgery' had been performed in 18.3 per cent. A total of 38.4 per cent had at least two operations. The revision rate in other conditions varied from 10 per cent (sequelae to chronic otitis) to 34 per cent (post-inflammatory acquired atresia). These rates are discussed and the functional results presented.

Cholesteatoma↗
PubMed1986

Fine needle aspiration biopsy in salivary gland tumours.

Of 105 tumours of the major salivary glands, 90 were benign and 15 malignant. In benign tumours a correct preoperative diagnosis was made by fine needle aspiration biopsy in 84%, and none were falsely classed as malignant. In the malignant tumours, only 8 out of 15 (53%) were correctly diagnosed as malignant while 7 were misdiagnosed as benign. It is concluded that in benign salivary gland tumours there is good accordance between fine needle aspiration biopsy and the final histological report, in contrast to the malignant tumours where this is less convincing. Fine needle aspiration biopsy is a valuable diagnostic tool, but the result should be carefully evaluated, regarded as only part of the clinical picture and not solely relied on.

Adenolymphoma↗
PubMed1986

Tympanoplasty in children. An analysis of late results.

The late results of tympanoplasty were analyzed three to fifteen years postoperatively in 124 ears of children aged 2 to 14 years with noncholesteatomatous chronic otitis. The primary graft take rate was 92% and only 4% of the ears had perforations at follow-up. The hearing results were very good. The overall results are similar in children operated on at the ages of two to seven years and in children operated on at the ages of 8 to 14 years. We recommend tympanoplasty in children of all ages, including preschool age.

Acoustic Impedance Tests↗