Biomedical subjects
Publications and source records attributed to T Lau.
We introduce a sequence of parameters called canonical moments to characterize the predictive value of the pattern of consensus among (kappa-1) ratings to an additional rating. The usual kappa coefficient of agreement among ratings (two or more) is just the second canonical moment. By using the higher canonical moments, we can evaluate the consensus of multiple binary ratings.
The late results of one stage operation for middle ear tymanosclerosis in 73 patients during the period January 1965 to December 1980 are presented. Mean observation time was 11.2 years (range 3-20.2 years), with a follow-up rate 86 per cent. Among 64 patients with stapes fixation, 59 had removal of tympanosclerotic masses and stapes mobilization, and five cases underwent stapedectomy. The series was divided into six groups and the results analyzed. The best and most stable results occurred in the group with stapes mobilization and an intact ossicular chain followed by the group with stapes mobilization and Type II tympanoplasty with incus interposition. The poorest late results were obtained in ears with lacking stapes crura and stapes mobilization, and in ears subjected to stapedectomy. No case of post-operative sensorineural hearing loss occurred. We recommend that care is taken to preserve an intact ossicular chain at stapes mobilization performed at the same stage as myringoplasty. Also in ears with a defective ossicular chain but intact stapes with tympanosclerotic fixation we recommend stapes mobilization in one stage. In ears with fixation of the stapes footplate and defective crura, we recommend stapedectomy or stapedotomy in two stages.
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The autopsy findings of 73 patients with uterine sarcoma were studied to determine the sites and possible modes of metastasis. Homologous mixed mesodermal tumors were the most frequent (41%) followed by leiomyosarcoma (26%), heterologous mixed mesodermal tumor (18.3%), stromal sarcoma (12%), and endolymphatic stromal myosis (3%). The peritoneal cavity and omentum were the most frequently involved sites (59%), followed by the lung (52%), pelvic lymph nodes (41%), paraaortic lymph nodes (38%), and liver parenchyma (34%). The presence of lung metastasis was not associated with pelvic or paraaortic node metastasis or intraperitoneal disease. Metastasis to other distant sites including the brain, heart, kidney, and bone were independent of pelvic and paraaortic nodal metastasis or intraperitoneal disease. Metastatic sites were not different among various histologic types. Distant metastatic sites were statistically associated with lung metastasis. Hematogenous metastasis best explains this metastatic pattern and adjuvant systemic therapy seems indicated.
The late results in 740 patients with cholesteatoma subjected to one-stage canal wall down mastoidectomy (262 patients), modified canal wall up mastoidectomy (324 patients), and tympanoplasty without mastoidectomy (154 patients) were analyzed with regard to hearing and the condition of the drum. Mean observation time was 9.3 years, range 3-21 years. Postoperative hearing (air bone gap and pure tone average) and as hearing at the last evaluation was significantly better in the canal wall up group, than in the canal wall down group, but also the preoperative hearing was better in the canal wall up group. The postoperative hearing was best in the group with tympanoplasty only without mastoidectomy. It is concluded that no single method is optimal in all cases of cholesteatoma and that cholesteatoma surgery should be individualized.
To obtain the best possible results of treatment of acquired cholesteatoma, we made a subdivision of cholesteatoma types into attic and pars tensa cholesteatomas, and subdivided the latter further into tensa retraction cholesteatoma and sinus cholesteatomas. Tensa retraction cholesteatoma is defined as arising from a retraction or perforation of the whole pars tensa, whereas sinus cholesteatoma is defined as arising from a retraction or perforation of the postero-superior part of the tensa. We present the long-term results obtained in tensa retraction cholesteatomas treated with one stage surgery from 1964 to 1980. Median observation time was 9 years, range 2 to 19 years. Sixty-one ears were treated without mastoidectomy, whereas 71 ears had canal wall-up mastoidectomy and 64 ears had canal wall-down mastoidectomy. The total recurrence rate was 13.3 per cent; 17 ears had residual cholesteatoma, and nine ears had recurrent cholesteatoma. The best results were obtained in ears with an intact ossicular chain where mastoidectomy was not performed. In 49 per cent of the cases, the cholesteatoma was confined to the tympanic cavity without reaching the aditus, antrum or mastoid process. About one-third to one-quarter of the ears had tympanoplasty only, with removal of the cholesteatoma through the ear canal.
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.
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.
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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.
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.
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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.
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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.
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.