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Biomedical subjects

M Tos

Publications and source records attributed to M Tos.

At least 37 records · Page 2Linked to original sources
PubMed2000

Middle fossa approach in vestibular schwannoma surgery. Postoperative hearing preservation and EEG changes.

When the middle fossa (MF) approach was introduced in Denmark, we were concerned about the possible risk to the temporal lobe caused by the retraction of the lobe when exposing the internal acoustic meatus. EEG recordings were therefore obtained prospectively before (21 patients) and after MF tumor removal (all 23 patients operated from 1989 to 1997). Only three patients had normal EEG recordings before and after surgery, while 86% had induction, or worsening, of focal and paroxystic activity, even at the last follow-up (median 3.5 years). Sixteen patients operated prospectively via the translabyrinthine (TL) also had pre- and postoperative EEG and served as a control group. Only minor EEG changes were found in this group. In neither group did the patients display any clinical neurological signs (seizures). At the latest evaluation the facial function was reduced in 8 patients (35%) with 6 patients going 1 step up the scale, 1 patient 2 steps up and 1 patient 3 steps up (from HB-1 to HB-4). The integrity of the facial nerve was maintained in all patients. Postoperatively, 10 patients (44%) had useful hearing (hearing class A and B) on the operated side. Four patients had anacusis and an additional 4 patients were reduced to hearing class D with very low PTA and SDS. In total, 9 patients (39%) retained their preoperative hearing class, while 14 patients (61%) had impairment in their hearing class. In conclusion, EEG changes (low frequency activity and IEA) may be provoked or worsened as part of the middle cranial fossa procedure. The mechanism is not fully known, but may reflect peroperative pressure on the temporal lobe. EEG changes are fewer and lighter in translabyrinthine-operated patients. The practical clinical implications of the possibility of developing EEG changes, even without clinical signs, are potentially serious, and must be included in the information given to the patients before surgery.

Adult↗
PubMed2000

Polyp and fibrous adhesion formation in acute otitis media caused by non-typeable or type b Haemophilus influenzae or Moraxella catarrhalis.

Among a variety of other histopathologic changes, polyps and fibrous adhesions are readily formed in the middle ear mucosa during experimental acute otitis media (AOM) caused by Streptococcus pneumoniae. Quantitative studies on experimental AOM caused by other bacteria have shown that some of these histopathologic changes, such as adaptive bone modeling and increase in goblet cell density, differ according to the type of bacteria. This investigation surveys polyp and fibrous adhesion formation in experimental AOM caused by either non-typeable or type b Haemophilus influenzae, or Moraxella catarrhalis. Seventy-five rats were inoculated with 1 of these 3 bacteria (25 rats in each of 3 groups). Five rats from each group were sacrificed on days 4, 8, 16, 60 and 180 post-inoculation. The middle ear mucosae were dissected and histopathologic changes in whole-mount and section preparations were studied using light microscopy. Polyps were found in most ears and in the greatest numbers on the early days; fewer polyps were found on the later days, regardless of the type of bacteria. However, non-typeable and type b H. influenzae induced formation of significantly more polyps than M. catarrhalis. The polyps were primarily located in the epitympanum. Fibrous adhesions were primarily located in the hypotympanum and formed in almost all ears, on all days post-inoculation, regardless of the type of bacteria. Numbers increased to a peak on day 16 and then decreased. Non-typeable and type b H. influenzae induced formation of significantly more adhesions than M. catarrhalis, and the middle ears displayed a higher number of persisting adhesions in the animals inoculated with non-typeable H. influenzae. We conclude that polyps and adhesions are formed in experimental AOM regardless of bacterial type, confirming a pathogenesis based on inflammation. Both types of H. influenzae induce formation of greater numbers of polyps/adhesions than M. catarrhalis, and the non-typeable form causes more adhesive sequelae in the mucosa than the encapsulated type b.

Acute Disease↗
PubMed2000

Adaptive bone modeling and remodeling in acute otitis media caused by non-typeable or type B Haemophilus influenzae or Moraxella catarrhalis.

Experimental studies have shown that acute otitis media caused by Streptococcus pneumoniae alters modeling dynamics in bone tissue structures surrounding the middle ear cavity. Initial resorption of bone is followed by formative activity, seen as massive osteoneogenesis. However, neither resorptive nor formative activity occurs in the otic capsule, supporting the existence of a perilymphatic zone of specialized bone. This study investigates adaptive bone modeling in acute otitis media caused by other bacteria frequently encountered in this disease. Seventy-five rats were inoculated with either non-typeable or type b Haemophilus influenzae, or Moraxella catarrhalis (25 rats in each group). Five rats from each group were sacrificed on days 4, 8, 16, 60 and 180 post-inoculation. Qualitative as well as quantitative histopathology revealed increasing apposition of new bone on both sides of the original bony wall of the middle ear bulla, i.e. at the inner and outer periosteum. Remodeling activity was seen on later days of sacrifice, as typical osteone (Haversian system) formation. Measured bone thickness in four anatomically well-defined localities progressed to a peak 2 months post-inoculation, followed by some degree of normalization. However, bone thickness was still massively increased 6 months after the acute incident. Except in the otic capsule, resorptive and formative activity was found in all bone tissue structures surrounding the middle ear cavity. These findings were irrespective of the type of inoculated bacteria. However, non-typeable or type b Haemophilus influenzae induces significantly more new bone formation than Moraxella catarrhalis. We conclude that acute otitis media caused by either of the bacteria is accompanied by massive and progressive net osteoneogenesis, already evident on day 4 and peaking 2 months post-inoculation, followed by some degree of normalization. Non-typeable and type b Haemophilus influenzae induce more new bone formation than Moraxella catarrhalis, whereas other features of bone histomorphology were equivalent. The present findings further support the existence of a perilymphatic zone of specialized bone.

Acute Disease↗
PubMed2000

Vestibular schwannoma growth: the continuing controversy.

OBJECTIVE: To investigate the growth of vestibular schwannoma (VS) in a series of 123 patients with 127 tumors allocated to the "wait and scan" group in the period 1973-1999. STUDY DESIGN: Retrospective review of prospectively registered data on all patients with VSIE from the entire country who were allocated to the wait and scan group. METHOD: Clinical charts, audiometric data, and neuroradiological images were reviewed and tabulated for age, hearing level expressed as speech reception threshold (SRT) and speech discrimination score (SDS), maximum extra-canalicular tumor extension, and possible changes in tumor diameter. The material was updated three times (in June 1993, June 1996, and June 1999). Via the Danish national register, data on whether the included patients were alive or dead were collected in 1999. RESULTS: The tumor growth, growth rate, and growth patterns were calculated in three periods 1973 to 1993 (mean observation period, 3.4 y), 1973 to 1996 (mean observation period, 3.8 y), and from 1973 to 1999 (mean observation period, 4.2 y). By termination of the first period, 94 tumors (74%) exhibited measurable growth, 23 tumors (18%) no measurable growth, and 10 tumors (8%) revealed negative growth. By the end of the extended observation period, tumor growth was observed in 104 tumors (82%), no tumor growth in 15 tumors (12%), and negative growth in 8 tumors (6%). Subsequent to the third observation period, growth was observed in 108 tumors (85%), no growth in 11 tumors (9%) and negative growth in 8 tumors (6%). However, the results may also be interpreted in another way: 52 patients (42%) were alive at the time of writing, tumor growth did not demand any intervention, 23 patients (19%) died as a result of non-tumor-related causes, and 35 patients (28%) were previously treated and alive by the termination of the third observation period. CONCLUSION: Depending on the observation period, three sets of growth results were obtained. The long observation period, updating and re-updating the results, gave us the opportunity for a de novo interpretation of the results and the long-term consequences of the wait and scan policy. Combined with other factors, the achieved results should be considered when timing of surgery is to be decided.

Adolescent↗
PubMed2000

A new pathogenesis of mesotympanic (congenital) cholesteatoma.

OBJECTIVES: To introduce a new, acquired pathogenetic theory of mesotympanic cholesteatoma behind an intact eardrum in children and to present some doubts on congenital pathogenesis. STUDY DESIGN: Literature review. METHODS: The incidence and origination of mesotympanic cholesteatoma in children were thoroughly analyzed in the world literature and correlated to the histopathological studies on human middle ear epithelia and to epidemiological studies on secretory otitis, tubal occlusion, and acute suppurative otitis media. RESULTS: The new, acquired theory is based on the fact that that the place of origin of the anterosuperior mesotympanic cholesteatoma is the area of the malleus handle and malleus neck, and of the posterosuperior cholesteatoma, the long process of the incus. During the common pathological conditions there is a great risk of retractions and adhesions of the eardrum to these ossicles. After subsequent loosening of the retracted eardrum some cells of the keratinized squamous epithelium may be left behind and become included into the tympanic cavity, eventually causing an inclusion cholesteatoma. Four basic mechanisms of inclusions are proposed and the presence of great dynamics in middle ear disease in children, with high incidence of tubal dysfunction, retractions, secretory otitis, and acute suppurative otitis, is documented, making the acquired pathogenesis probable. The place of origin does not fit with the congenital pathogenesis of epithelial formation localized on the lateral wall of the eustachian tube close to the annulus. The origination around the malleus and incus fits better with the proposed acquired pathogenesis. CONCLUSIONS: There are no definitive proofs for the acquired pathogenesis of the mesotympanic cholesteatoma, nor is there experimental research to prove or disprove it. Mesotympanic cholesteatoma, congenital cholesteatoma, acquired pathogenesis of mesotympanic cholesteatoma, cholesteatoma in children, cholesteatoma behind intact eardrum.

Child↗
PubMed2000

Results of tympanoplasty in children after 15 to 27 years.

Results of tympanoplasty in children with noncholesteatomatous chronic otitis media are presented in a 16- to 27-year follow-up. During the 13-year period from 1968 to 1980, 116 children (124 ears) were operated on, and they were submitted to several follow-ups with audiometry and otomicroscopy. The attendance at the last follow-up was 70%, and the minimum time since surgery for these patients was 15 years. All dry ears were operated on transcanally with a fixed ear speculum, without any lateral incision of the ear canal skin. Cumulatively, in total, 14 ears (11%) had reperforation: 7 ears early and 7 ears late. At 6 months, there were 6% early reperforations; some were surgically closed and some reappeared later, even after several years, as late perforations. At 2 to 15 years of follow-up, there were 4% reperforations, and at 16 to 27 years, 6%. Hearing was good and stable. The results were the same in ears operated on at the ages of 2.5 to 7 years and 8 to 14 years, as well as with preoperatively positive and negative Valsalva maneuvers. In total, 14% of ears were revised during the entire observation period. It is concluded that transcanal tympanoplasty, even in young children, has good long-term stability and can definitively and permanently solve the problem of noncholesteatomatous chronic otitis in children.

Adolescent↗
PubMed2000

Cystic vestibular schwannoma: surgical outcome.

We investigated the proportion of the cystic form of vestibular schwannoma and assessed the results of surgery in this subtype of the condition. The definition of cystic vestibular schwannomas was based on the following criteria: per-operative identification of cystic components; occurrence of the hypodense/hypointense areas on computed tomography (CT) and/or magnetic resonance (MR); and histological verification of S-100 protein membrane-like structures. In a study of 773 Danish patients with vestibular schwannomas, 44 (5.7 per cent) displayed cystic components. The outcome of surgery on 44 cystic vestibular schwannoma (mean tumour size 39 mm) was evaluated and compared with that for 151 solid grant vestibular schwannoma (mean tumour size 49.8 mm). Per-operatively, we found a substantially higher adherence to different intracranial structures in the solid giant vestibular schwannoma compared with the cystic vestibular (95 per cent vs 70 per cent for brainstem, 91 per cent vs 59 per cent for trigeminal nerve, 85 per cent vs 45 per cent for cranial nerves X and XI, 67 per cent vs 32 per cent for dura). Nevertheless, the preservation of the facial nerve function was much better in patients with solid giant vestibular schwannoma compared with those with cystic vestibular schwannoma (House-Brackmann facial nerve dysfunction grade 6 (one year post-operative): 27 per cent vs 41 per cent, respectively p < 0.04). We conclude that the cystic components in vestibular schwannoma are associated with a less favourable surgical outcome, probably due to the rapid tumour growth and symptoms caused by compression of the posterior fossa structures.

Adult↗
PubMed2000

Isolated congenital stapes ankylosis: an embryologic survey and literature review.

OBJECTIVE: Isolated congenital stapes ankylosis is rare but is a definite entity. Both small series and case reports have been published in various languages. The aim of this study was to review the world literature regarding isolated congenital stapes ankylosis and to critically evaluate the embryonic development of the stapes to explain the possible pathologic development of this ankylosis. DATA SOURCES: All the publications in the English, German, and French literature regarding congenital stapes anomalies were reviewed, and original research articles on the embryonic development of the stapes and related structures were extensively and critically reviewed. STUDY SELECTION: Of the many varieties of congenital stapes anomalies described in the literature, only the isolated congenital stapes fixation due to footplate or suprastructure fixations were selected in this study. DATA SYNTHESIS: After extensive and critical review of the embryonic development of the stapes, the complex and confusing embryonic development is explained in a simplified way with schematic illustrations for easy understanding. The possible theories of congenital stapes ankylosis are explained on an embryologic basis and supplemented with schematic illustrations. CONCLUSION: Based on the development of the stapes an attempt has been made to explain the possible theories for the basis of suprastructure fixation. Theories of congenital fixation of footplate also discussed.

Ankylosis↗
PubMed2000

Middle ear secretory capacity after acute otitis media caused by Streptococcus pneumoniae, Moraxella catarrhalis, non-typeable or type B Haemophilus influenzae. A comparative analysis based on goblet cell density.

To investigate whether the type of bacteria is correlated with an increase in goblet cell density during and after acute otitis media, we inoculated the middle ear of 25 rats with either Streptococcus pneumoniae, Moraxella catarrhalis, non-typeable or type b Haemophilus influenzae. Mucosal goblet cell density was determined by a whole-mount method on days 4, 8, 16, 60 and 180 post-inoculation. The goblet cell density was increased on all days of sacrifice, employing either bacteria, except M. catarrhalis 6 months after the acute incident. Type b H. influenzae induced the highest increase, followed by non-typeable H. influenzae, S. pneumoniae and M. catarrhalis. The mucosal area containing goblet cells was enlarged on all examination days, employing either bacteria. We conclude, that mucosal secretory capacity is highly increased during and up to 6 months after acute middle ear infection caused by either bacteria, conceivably predisposing a subsequent development of secretory otitis media. The results indicate that type b H. influenzae seems to be the bacteria most likely to induce a subsequent secretory condition.

Acute Disease↗
PubMed2000

Incidence of vestibular schwannoma in Denmark, 1977-1995.

OBJECTIVE: To establish the incidence rate of vestibular schwannomas (VS) (acoustic neuromas) in Denmark. BACKGROUND: The worldwide incidence rates of VS vary from 1 to 20 cases per million population per year. METHODS: The nationwide and population-based age-specific, sex-specific, and calendar year-specific incidence rates of VS in Denmark between 1977 and 1995 are presented. Information on cases of VS was obtained from the Danish Cancer Registry and a clinical database situated at the University Hospital of Gentofte. A total of 795 cases were reported during the period of the study. RESULTS: The incidence rate increased from 5 cases per million population per year in 1977-1981 to 10 cases in 1992-1995; the increase was from 5 to 11 cases among women and 5 to 9 cases among men. The age-specific incidence rates show that VS is rarely diagnosed in persons under 30, but the incidence rate appears to increase among women after menopause. CONCLUSION: The overall incidence rate of VS increased linearly during the study period, probably owing to the introduction of more precise diagnostic procedures, increased awareness among physicians and patients of the symptoms of VS, improved registration of benign tumors in Denmark, and the use of data from two sources.

Adolescent↗
PubMed2000

Pathogenesis of attic cholesteatoma: clinical and immunohistochemical support for combination of retraction theory and proliferation theory.

OBJECTIVE: The aim of the current study was to provide support for a combination of the retraction and proliferation theories of acquired cholesteatoma. BACKGROUND: There is clinical evidence for formation of a retraction, but there is a lack of explanation for the transition from a retraction pocket to an active and expanding attic cholesteatoma. METHODS: Epidemiologic studies on the incidence of attic retractions and follow-up studies on patients with attic retractions were performed. Additionally, expression of proliferation marker and analysis of basement membrane were studied in samples of attic cholesteatoma. RESULTS: The prevalence of attic retractions was between 14% and 25% of investigated ears. In children with manifest secretory otitis, there were some attic cholesteatomas and 5% to 6% severe retractions. Some of them became precholesteatomas, requiring treatment and controls. Immunohistochemistry of attic cholesteatomas showed that proliferating keratinocytes were very often seen within epithelial cones growing toward the underlying stroma. These growth cones exhibited focal discontinuities of the basement membrane, especially in areas of intense subepithelial inflammation. CONCLUSIONS: As a possible explanation based on clinical and immunohistochemical findings, the authors propose a four-step concept for the pathogenesis of cholesteatoma that combines the retraction and proliferation theories: (a) the retraction pocket stage; (b) the proliferation stage of the retraction pocket, subdivided into cone formation and cone fusion; (c) the expansion stage of attic cholesteatoma; and (d) bone resorption.

Adolescent↗
PubMed1999

[Treatment of malignant parotid tumors. Results from the county of Copenhagen].

Out of 494 parotid gland tumours treated in Copenhagen county (population 600,000 inhabitants) in the period 1986 to 1995, 50 patients (tumours) were proven to be malignant, making an incidence of 0.62/100,000 per year. Age ranged between 14 and 87, mean 64 years. According to the UICC classification system, six tumours (12%) were classified as stage I, 23 (46%) as stage II, 14 (28%) as stage III and 7 (14%) in stage IV. Four therapeutic modalities were applied: surgery only, surgery + radiation, surgery + chemotherapy and surgery + chemotherapy + radiation. Surgical radicality was achieved in 76% and radicality was unrelated to tumour histology. Normal or nearly normal facial nerve function (HB1&2) was noted at last follow up in 60%. Five year crude survival for all patients were 68%. Survival was not depends on N-classification. Patients in stage I had a better survival compared to patients in stage II, III and IV. No statistically significant difference in five year crude survival between the radically operated patients (n = 38) and patients with residual tumour (p = 0.27, log rank-test), (p = 0.48 chi2-test was found.

Adolescent↗
PubMed1999

Cholesteatoma in children, predictors and calculation of recurrence rates.

The aim of the study was to evaluate the long-term recurrence rate after surgery for acquired cholesteatoma in children, to search for predictors of recurrency and to analyse the impact of the applied statistical method on the outcome of the results. During a 15-year period, 114 children underwent first-time surgery for acquired cholesteatoma. The patients were re-evaluated with a median observation time of 5.8 years, range 1-16 years. Recurrence of cholesteatoma developed in 27 ears. The cumulated total recurrence rate was 24% using standard incidence rate calculation, applying Kaplan-Meier survival analysis the recurrence rate was 33%. Recurrent disease occurred significantly more frequent in children < 8 years, with negative preoperative Valsalva, ossicular resorption and with large cholesteatomas. In conclusion, young children with poor Eustachian tube function, large cholesteatoma and erosion of the ossicular chain, are at special risk of recurrence and should be observed several years after surgery.

Adolescent↗
PubMed1999

[Diagnosis and growth evaluation of vestibular schwannomas by SPECT combined with TL-201 thallium].

The value of SPECT scanning in diagnosis and growth potential of vestibular schwannoma (VS) was investigated in a series of 29 patients. SPECT demonstrated all tumours > 0.8 cm3, but had limitations as a diagnostic modality of small intracanalicular tumours, when compared to gadolinium DTPA enhanced MR. SPECT was found to be valuable in determining VS growth potential as it reflects tumour vascularity, which is essential for tumour growth. A high radioactive tracer uptake in the tumour corresponded to high tumour vascularity, indicating a high growth rate and vice versa. 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 tumour.

Adult↗
PubMed1999

[Results of bat ear surgery over a period of ten years].

A material of 286 patients or 545 ears submitted to operation for protruding ears operated by Stenströms and Nordzells surgical procedure over a period of ten years were reviewed retrospectively. One hundred and sixty-three patients were clinically investigated and interviewed. The mean observation time was eight years. Satisfactory results were obtained in 94% of the patients subjectively. Objectively there was a good result in 74% of the cases. Relatively few complications and reoperations occurred. However 20% of the patients interviewed had postoperative pain more than one year after the operation. The results of the operations are reviewed and discussed. There was no significant difference between the results of the surgical procedure a.m. Stenström and a.m. Nordzell.

Adolescent↗
PubMed1999

[Cochlear implantation in children. The first Danish results].

The aim of this study is to review indication, technique and results of cochlear implant (CI) treatment with Nucleus CI-multi-electrode of the first ten children operated in Denmark (five children with congenital deafness and five with acquired prelingual deafness due to meningitis). In the literature, the importance of early referral and operation at the age 2-3 (4) years for congenital deafness and as soon as possible on suspicion of acquired deafness (meningitis) is stressed. A short survey of our indications, technique and rehabilitation is presented. The results of treatment after 11-44 months' use of CI are that one child has language almost matching age, four use words and short sentences accompanied by support signing, three have sound reaction and say single words without sentence building, but of these two children have only used CI for a very short time and are improving. Two meningitis sequelae cases had cochlear ossification, which made the implantation difficult. Both patients had to be operated, and one of them is not using the processor.

Age Factors↗
PubMed1999

Less radical drilling in surgery for exostoses of the external auditory canal.

OBJECTIVE: To estimate the anatomical and functional long-term result of surgery for ear canal exostosis. METHODS: Case rapport review with extraction of data concerning pre- and postoperative anatomical conditions, symptoms and audiology and a clinical and audiological re-evaluation. In the 20-year-period from 1 January 1976 to 1 January 1996, 26 patients were operated on primarily for ear canal exostosis. 19 patients with in total 24 ears were re-evaluated. Control-period 7.2 years. Pre-operatively were found occluding ear-canal exostosis in all patients as well as hearing loss, otitis externa and pain. RESULTS: At the re-evaluation all patient were completely free of their symptoms. 19 out of 24 ears still had some remnants of exostosis, but the ear canal was covered with completely normal skin and had normal migration properties. No signs of re-growth were found in this material. Postoperatively one patient had a sensorineural hearing loss of 85 dB at 6 kHz, one had a dehiscence of the temporomandibular joint and one patient had an anterior ear drum perforation. CONCLUSION: To avoid the complications a less radical drilling of exostoses is proposed, in particular along the superior wall and near the short process of the malleus handle and along the anterior tympanomeatal angle. Removal of the bone from the posterior, inferior and anterior walls with preservation of the canal skin, creates enough lumen providing permanent cure.

Adolescent↗