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Biomedical subjects

M Tos

Publications and source records attributed to M Tos.

At least 73 records · Page 4Linked to original sources
PubMed1998

Postinflammatory acquired atresia of the external auditory canal: treatment and results of surgery over 27 years.

Postinflammatory, acquired atresia of the external auditory meatus is a relatively rare consequence of chronic otitis media or recurrent external otitis with an annual incidence of 0.6 cases per 100,000 inhabitants. Primary and late results after operative treatment of this condition in 53 ears over 27 years are presented. Perioperative findings are described, and an outline of applied surgical technique is given. Six patients had bilateral involvement. The male-to-female ratio was 1:2, median age at surgery was 46 years, and the median follow-up period was 5 years (range, 4 mo to 13 y). In 11% of the cases, recurrent atresia developed. Early operation is recommended, because cholesteatoma behind the atresia was found in 9%. Hearing improvement has been considerable after removal of the atresia with primary closure of airbone gap within 20 dB in 90% of the cases.

Adolescent↗
PubMed1998

Effect of penicillin on formation of fibrous adhesions in acute otitis media.

Fibrous middle ear adhesions are occasionally encountered in middle ear surgery and may cause a hearing impairment. Although usually associated with chronic otitis media, adhesions are also found following a single episode of experimental acute suppurative otitis media, suggesting a pathogenesis based on the inflammatory process engaging acute infection. In a well-established rat model of pneumococcal acute otitis media, we report on the effect of penicillin V on formation of fibrous middle ear adhesions. Previous studies have shown marked impact of penicillin on mucosal goblet cell density and other histopathologic features. Number, anatomic localization, and histopathologic morphology of adhesions were assessed in a longitudinal study of 25 normal, 25 untreated, and 25 treated rats. Although penicillin administration induced a slight tendency toward fewer ears with adhesions and fewer adhesions per ear, these changes were nonsignificant. Histomorphology and the general pattern of anatomic localization of adhesions were unaffected by penicillin administration. We conclude that administration of penicillin has an inconspicuous effect on the formation of fibrous adhesions in experimental acute otitis media caused by Streptococcus pneumoniae.

Acute Disease↗
PubMed1998

Effect of penicillin on polyp formation in acute otitis media.

HYPOTHESIS/BACKGROUND: The mucoperiosteal lining of the middle ear cavity is subject to radical changes during and after acute infection. Among these is the formation of mucosal polyps. Previous studies on experimental acute otitis media have shown a marked impact of penicillin on mucosal histomorphology. This study reports on the effect of penicillin administration on polyp formation. METHODS: The mucosa of 75 rat middle ears in a model of acute otitis media was examined. Whole-mount and section preparations from 25 normal ears, 25 ears inoculated with Streptococcus pneumoniae, and 25 inoculated, penicillin-treated ears were inspected for number, size, anatomic localization, and histopathologic morphology of occurring polyps. RESULTS: The total number of polyps was unaffected by penicillin administration, although polyps occurred in fewer ears. The polyps from treated ears tended to be smaller and stalky, appeared later in the timespan covered, and often were located around the tubal orifice. Histopathologic morphology of polyp base, core, and epithelial covering was otherwise unaffected by penicillin. CONCLUSIONS: Administration of penicillin has inconspicuous effect on the formation of polyps in experimental otitis media caused by S. pneumoniae in contrast to a marked impact on mucosal goblet cell density and other histopathologic features reported in previous studies.

Acute Disease↗
PubMed1998

Point prevalence of secretory otitis media in children in southern Vietnam.

Few reliable data exist on the prevalence of secretory otitis media (SOM) in the Third World. A large epidemiologic cross-sectional study was undertaken in two communes in southern Vietnam to study an urban and a rural community during two different climatic conditions: the dry and rainy seasons. The participants included 3,300 children (6,598 ears) ages 6 months to 10 years. Otolaryngological and medical histories were obtained, and an otolaryngological examination was carried out on 1,669 children in April 1995 (the dry season) and on 1,631 children in December 1995 (the rainy season). Tympanograms were obtained (n = 6,055), 429 of which were type B curves. The overall prevalence of SOM was 7.1%, the highest incidence was at the age of 2 years (with a prevalence of 22%), and there was a significantly higher prevalence of SOM during the rainy season than during the dry season. No significant difference in incidence was found in the urban district as compared to the rural district.

Acoustic Impedance Tests↗
PubMed1998

Importance of eustachian tube function in middle ear surgery.

Poor eustachian tube function plays a major role in the pathogenesis of chronic secretory otitis media. This is illustrated by epidemiologic studies of secretory otitis media and long-term studies of treated secretory otitis. Evaluation of hearing results demonstrate that effective preoperative and postoperative tubal function is highly important for good surgical outcome in cases of chronic otitis and cholesteatoma.

Acoustic Impedance Tests↗
PubMed1997

A long-term follow-up study of nasal polyp patients after simple polypectomies.

A long-term follow-up study was performed on randomly selected patients after simple snare polypectomies. There were 243 patients, of whom 211 underwent endoscopic examination. There were 154 males and 57 females and median age was 57.7 years. Median period of follow-up was 8 years (range, 38-145 months). The median number of polypectomies was 1.6 (range, 1-15). Polyp eosinophilia was recorded in 97% of the cases. From life-table analysis the 5-year rate for two or less polypectomies was 80% (95% confidence intervals, 75-86%). Symptoms and findings were recorded at a median time of 56 months from the last polypectomy. At this time 70% of the patients denied blocked nose or excessive secretions. Seventeen per cent of the group claimed loss of sense of smell, while 28% stated that it was poor. At follow-up, large polyps were found in 3% of the patients, moderately sized ones in 30% and small in 42%. No polyps were visible in 25%. Patients with asthma (26%) had more polypectomies than those without (median, 2.4 versus 1.4). Patients with a history of non-steroidal antiinflammatory drug intolerance (7%) had the highest number of polypectomies. Previous troublesome sinusitis and allergy seemed not to exert major influence on the number of polypectomies needed. In the primary care of nasal polyp patients, the majority only need minor or limited surgery or only medical treatment.

Adult↗
PubMed1997

Increased secretory capacity of the middle ear mucosa after acute otitis media caused by Haemophilus influenzae type B.

Secretory otitis media is associated with a highly increased goblet cell density of the middle ear mucosa. Previous studies have shown that a single episode of experimental acute otitis media caused by Streptococcus pneumoniae or nontypeable Haemophilus influenzae is followed by increased goblet cell density for a period of at least 6 months. This condition may create a predisposition for subsequent development of secretory otitis media. We inoculated the middle ears of 25 rats with type B H. influenzae to determine the effect of the bacteria on mucosal secretory capacity. Five rats were euthanized 4, 8, 16, 60, and 180 days after inoculation, followed by dissection, staining, and whole-mount embedding of the middle ear mucosa. The goblet cell density was determined in 24 well-defined localities. Compared with that of 25 normal middle ears, the goblet cell density was significantly increased in almost all counting localities on all days of euthanasia. Thus increased goblet cell density and enlargement of mucosal areas containing goblet cells persisted for 6 months after the acute incident. Inoculation of type B H. influenzae induced an increase of goblet cell density that was higher than the increase after inoculation of S. pneumoniae or nontypeable H. influenzae. We conclude that experimental acute otitis media caused by type B H. influenzae is followed by a longstanding increase of mucosal secretory capacity, which is likely to induce a subsequent development of secretory otitis media.

Acute Disease↗
PubMed1997

Translabyrinthine vestibular schwannoma surgery: postoperative tinnitus and cochlear nerve integrity.

Cochlear neurectomy as a surgical treatment for tinnitus is known to be only partially successful in many conditions. Translabyrinthine surgery for acoustic neuromas may be performed using a dissection technique which preserves an 'anterior curtain' which helps to protect the facial nerve. The cochlear nerve may be retained within this tissue though it can be cut during the dissection. To assess whether its integrity affects tinnitus the video recordings of 117 patients undergoing this operation were reviewed to grade the likelihood of the cochlear nerve having been retained intact. A postal questionnaire, with a response rate of 83%, was used to assess tinnitus. Patients who had a probable or definite nerve section had significantly lower postoperative tinnitus severity. The same relationship was found when patients were matched for tumour size and preoperative tinnitus. This procedure could act as a model for the effect of cochlear neurectomy on tinnitus associated with acoustic neuromas in a prospective trial.

Adult↗
PubMed1997

Thallium chloride 201Tl combined with single photon emission computed tomography (SPECT) in the evaluation of vestibular schwannoma growth.

Thallium chloride 201Tl combined with SPECT was performed in a series of 29 patients with neuroradiological evidence of vestibular schwannoma (VS). The relative tumor uptake (U) and relative tumor concentration (C) of the radiotracer 201Tl was determined, and the cerebellum served as a reference. The relative tracer concentration and uptake were correlated to tumor volume determined by gadolinium DTPA enhanced MR, to prediagnostic duration of symptoms, to tumor vascularity expressed by the average number of intratumoral vessels using the endothelial marker CD31, and to the proliferative activity in the tumors expressed by positive staining with the monoclonal antibody MIB-1 for Ki-67. A positive 201TI enhancement was detected in 17 tumors (n = 17). Tumors U and C were statistically unrelated to tumor volume (p = 0.236 and p = 0.439). SPECT demonstrated all tumors > 0.8 cm3, but it had its limitation as a diagnostic modality of small intracanalicular tumors, when compared with gadolinium DTPA enhanced MR. Relating U and C in all tumors (n = 29) and the prospectively registered data on the prediagnostic duration of symptoms, a statistical significance was found (p = 0.012 and p = 0.015). No statistically significant correlation was observed between U and C and the proliferative activity of the tumors expressed by positive staining with the monoclonal antibody MIB-1 for Ki-67 (p = 0.063 and p = 0.086). A statistically significant correlation was noted between C and U in the operated group (n = 12) and tumor vascularity expressed by the average number of the intratumoral vessels (p = 0.003 and p = 0.014). SPECT was found to be superior to MR in determining VS growth potentials as it expresses tumor vascularity, which is essential for tumor growth. It seems that we now have an in vivo functional radiological modality capable of providing data on VS vascularity and determination of growth potential in the individual tumor. A high radioactive tracer uptake in the tumor corresponded to high tumor vascularity, indicating a high growth rate and vice versa.

Adult↗
PubMed1997

Increase of diagnosed vestibular schwannoma in Denmark.

The incidence of acoustic neuroma/vestibular schwannoma (VS) in Denmark, with a population of approximately 5 million inhabitants was estimated in 3 periods: June 1976-June 1983, July 1983-June 1990 and July 1990-December 1995. The incidence of tumors increased from 7.8 tumors per million per year in the first period to 9.5 tumors per million per year in the second period. The figure of 12 tumors per million per year is established in the third period. A significant increase of the newly diagnosed intracanalicular and small tumors, with an extracanalicular extension of 1-10 mm was observed in the third period compared with the first 2 periods. Correspondingly a decrease in the newly diagnosed giant tumors was noted in the last 2 periods compared with the first period.

Denmark↗
PubMed1996

[Extra-nasal microscopic dacryocystorhinostomy].

A microsurgical extranasal dacryocystorhinostomy, incorporating the lacrimal sac into the nasal cavity by creating a flap of the lacrimal sac mucosa and suturing it to the nasal mucosa is described. The results from 81 patients (84 eyes) with chronic epiphora operated during the period of 11 years from 1980 to 1991 are described and analyzed. The long term results on 84 eyes with a median observation time of five years demonstrated good stability of the primary results. Only one patient (2%) with distal tear duct stenosis had chronic epiphora at the re-evaluation.

Adolescent↗
PubMed1996

Coronal CT of the paranasal sinuses before and after functional endoscopic sinus surgery.

Coronal CT of the paranasal sinuses and the ostiomeatal complex (OMC) was performed before and 12 months after bilateral functional endoscopic sinus surgery (FESS) in 30 patients with sinusitis and 12 patients with nasal polyposis. The extent of sinus mucosal thickening was graded, and the patency of the OMC was evaluated. After FESS, the percentage of open OMCs had increased from 42% to 83% in the sinusitis group, and from 8% to 45% in the polyposis group. There was only a small improvement in mucosal score in sinuses with opened OMC, so that the overall extent of sinus opacification before and after FESS was almost the same. Despite this, 91% of the patients reported clinical relief of symptoms. Preoperative coronal CT of the paranasal sinuses serves as an anatomical map for the surgeon, but there is no benefit of routine postoperative CT.

Adult↗
PubMed1996

Pathogenesis of middle ear adhesions.

Middle ear adhesions are well-known to the ear surgeon, although data on etiology, pathogenesis, and significance are lacking in current literature. This study on experimental acute otitis media presents histopathological data on these aspects. Pneumococci were inoculated in the right middle ear bulla of 25 rats; the left ear served as control. At days 4, 8, 16, 90, and 180, respectively, 5 rats were decapitated, and the bullae were removed, opened, and stained with periodic acid-Schiff (PAS)/alcian blue. The entire middle ear mucosae were dissected from the bone, embedded as whole mounts in colophonium chambers, and examined by light microscopy. Representative parts of the mucosae were sectioned and examined in the same way. All inoculated ears from day 8 and later (20 in total), contained mucosal adhesions of various sizes, shapes, and locations. None were found in control ears. The site of predilection for the development of adhesions was the hypotympanum, followed by the anterior epitympanum, the attic, the drum, the interossicular spaces, and the tubal orifice. Based on present histopathological findings, we conclude that the middle ear adhesion is a pathological phenomenon caused by infection, and we propose a six-stage hypothesis of pathogenesis: 1. Localized epithelial rupture; 2. Prolapse of subepithelial tissue; 3. Epithelialization of the prolapse; resulting in a polypous/fold-like prominence; 4. Growth and elongation of the prominence; 5. Fusion of the end/tip of the prominence with another part of the mucosa; 6. Formation of an adhesion.

Acute Disease↗
PubMed1996

Endolymphatic sac surgery: why we do not do it. The non-specific effect of sac surgery.

Three of the present authors described a trial in 1981 which showed that cortical mastoidectomy was as effective as an endolymphatic sac shunt in controlling vertigo in patients with Ménière's disease both on a short-term as well as a long-term basis. The hearing was not influenced by the treatment and any change was considered to be the result of time, rather than the effect of the surgery. Upon perusal of the literature only two other studies exist resembling our study, and they both reached the same conclusion, that sac surgery is at best non-specific and at worst of no value. None of the numerous other studies published have convinced the authors that sac decompression is specific in nature. We have also looked at ECoG as a means of proving the specificity of sac operations and come to the same conclusion that the existing information is conflicting and confusing, and cannot be used to prove anything about sac surgery. The present conclusion is therefore that in treating patients with Ménière's disease anything goes, even sac surgery.

Audiometry, Evoked Response↗
PubMed1996

Nerve growth factor receptor expression in heterotransplanted vestibular schwannoma in athymic nude mice.

Nerve growth factor (NGF) has the potential to induce cellular differentiation in various neoplastic and non-neoplastic cell lines. The purpose of the present study was to determine by immunohistochemistry: the presence/distribution of nerve growth factor receptor (NGFr), cellular proliferation expressed by Ki-67, and intratumoral vascularization visualized by the endothelial marker CD 31, in a series of 61 human vestibular schwannoma heterotransplants in athymic nude mice. The immunohistochemical results were correlated to the observed macroscopic growth in 22 heterotransplants (36%) with obvious macroscopic growth, versus 39 heterotransplants (64%), that were stationary or regressed. The positive immunoreactivity to NGFr, number of Ki-67 positive nuclei and number of intratumoral vessels were significantly higher in the 22 (36%) growing heterotransplants than in the 39 heterotransplants (64%), which were stationary or regressed (p < 0.00005, p = 0.046, p < 0.00001). NGFr was statistically related to the vascularity of the heterotransplants expressed by CD 31 (p<0.00001). No significant relation was observed between NGFr and the proliferation, as estimated by Ki-67. The results revealed that the macroscopic growth of VS in athymic nude mice was associated with strong positive expression of NGFr, high cellular proliferation expressed by Ki-67 and vivid neovascularization expressed by CD 31. The possible clinical applicability of the achieved results is discussed.

Animals↗
PubMed1996

Mast cell clusters in pars tensa membranae tympani in acute otitis media: a possible role in perforation healing.

Mast cells are known to reside in pars flaccida membranae tympani and other parts of the middle ear mucosa in both rats and humans. However, the normal pars tensa contains no or only a few mast cells along the manubrial vessels. We examined the pars tensa of 25 rats in an experimental model of acute otitis media and found 13 mast cell clusters in 6 membranes. A majority of clusters were located in the anterior, superior quadrant and contained from 3 to 23 cells. The mast cells resided immediately under the inner epithelial lining or in the intermediate, fibrous layer. In two membranes mast cell clusters were found in the margin of apparently healed spontaneous perforations. We conclude that mast cells in some cases infiltrate pars tensa membranae tympani in the late and receding phase of acute otitis media. As these cell clusters in some cases were found immediately around apparently healed membrane perforations, we propose that the mast cell might participate in the repair processes of tympanic membrane perforation healing. This is supported by recent studies in wound healing and functions of a number of mast cell mediators.

Animals↗
PubMed1996

Growth of vestibular schwannomas: in situ model employing the monoclonal antibody Ki-67 and DNA flow cytometry.

Vestibular schwannoma (VS) growth potentials were studied in an in situ model, in which the cycling cellular fraction was determined immunohistochemically by applying the mouse monoclonal Ki-67 antibody, and the tumor ploidy was estimated by DNA flow cytometry in a consecutive series of 124 VSs. The tumors were classified according to the average number of positively stained nuclei in 10 high-power fields into three groups: 28 highly (> 10), 33 moderately (> 5-10) and 63 low proliferating (< or = 5). The intratumoral proliferative variation was studied in 10 tumors. Only slight variation in the number of the positively stained nuclei were observed. Six of seven tumors removed because of macroscopically documented growth by computed tomography (CAT) scan were moderately or highly proliferative. Proliferation of VS was correlated to prospectively registered clinical data. A statistically significant relation was found between VS proliferation and the prediagnostic duration of symptoms (p = 0.0001). The proliferative status was unrelated to age, sex, and tumor size. Flow-cytometric determination of DNA index of the 124 tumors revealed 12 tetraploid (DNA index = 2), 110 diploid (DNA) index = 1) and two nondiploid tumors. A statistically significant relation was noted between tumor ploidy and proliferation status expressed by Ki-67 (p = 0.024). The tetraploid tumors showed significantly lower proliferation compared with the diploid tumors. Tumor ploidy was statistically unrelated to age, sex, tumor size, and duration of symptoms. The results of this study provide a link between the immunohistochemical, flow cytometric findings, and clinical data, which could probably be relevant in identifying patients at risk for rapid tumor growth and tumor recurrences, because a rapid test for cell proliferation is now available.

Adult↗