Biomedical subjects
Publications and source records attributed to M Tos.
Two different approaches, i.e. the anterior approach and the combined approach, for en bloc removal of the ethmoidal and ostiomeatal complex are described. In both techniques the contours of the face are completely maintained. Preliminary studies of prevalence of nasal polyps found by using these methods are described.
Semi-implantable hearing aids consisting of permanent middle ear implanted magnet, either partial ossicular replacement prostheses (PORP's) or total ossicular replacement prostheses (TORP's) driven by an electromagnet placed in the ear canal have been tested on six patients undergoing surgery for chronic otitis. The surgical and audiological problems are described. The audiological results were excellent in all six cases. A functional gain of 40-70 dB can be obtained for entire frequency range of the audiogram.
In a prospective study of 12 patients undergoing operation for acoustic neuromas, the hearing on the contralateral ear was tested before and systematically after operation. In 11 cases a perceptive loss of at least 20 dB was found at one or more frequencies during the first two postoperative weeks. The maximal average threshold decrease was 16.5 dB in the treble and 19.6 in the low frequencies. After three months the hearing had normalized in all cases. The loss of cerebrospinal fluid during operation diminishes the CSF pressure, which is then transmitted to the perilymph via the cochlear aqueduct, producing a transitory perilymphatic hypotonia and a relative endolymphatic hypertension mimicking an endolymphatic hydrops.
The annual incidence of diagnosed acoustic neurinomas in Denmark during two 7-year-periods from mid 1976 to mid 1990 is compared. Data on all patients operated via the translabyrinthine, transtemporal and suboccipital approach, as well as data on non-operated patients, was collected from the entire country. During the first period, from June 1976 to June 1983, the incidence was 7.8 tumors per million per year. During the second period, from June 1983 to June 1990, the annual incidence rose to 9.4 tumors per million per year. The number of newly-diagnosed small tumors increased, and that of large tumors decreased. A significant increase was observed in Copenhagen. An incidence of 11 to 12 tumors per million per year, or nearly 60 newly-diagnosed tumors per year is thus expected around the year 2000. This limited number supports the continuation of the present centralized model of acoustic neurinoma surgery in Denmark.
In the period from 1979 to 1990, a series of 59 patients with 59 acoustic neuromas were operated upon in five departments of neurosurgery by at least five different neurosurgical teams, employing the suboccipital approach. The perioperative mortality rate was 8.5%. Complications including hematoma, ventricular hemorrhage, meningitis, hemiparalysis, abducens nerve paralysis, recurrent nerve paralysis, postoperative wound infection and CSF leak were observed in 21 patients (35.6%). Radical removal of the tumor was not possible in 17 patients (28.8%). Converting the postoperative facial nerve function to the House-Brackmann (HB) classification, 34 patients (57.6%) were regarded as HB VI. Reconstruction of the facial nerve was attempted in 19 patients (32.2%). Attempts at preservation of hearing were unsuccessful in all patients. Failure to attain better results and the importance of the centralized Danish model of acoustic neuroma surgery are emphasized.
This investigation was performed in order to evaluate the observer variations in facial nerve function after surgery for an acoustic neuroma. From 1976-90, 507 patients were operated on by the same surgical team (M.T. and J.T.) using a translabyrinthine approach. One hundred and forty-four patients living in Copenhagen City and County were invited for interview and objective examination. Only 128 patients attended the interview and examination which were carried out by the same ENT physician. Data concerning observation of the facial nerve function only is presented. Its function was clinically evaluated (using the House and Brackmann (1985) grading scale) by two different observers i.e. the ENT physician and one of the surgeons. The patients were asked face-to-face with the ENT physician to estimate the degree of facial nerve function according to a 0-100 per cent scale. Comparing normal and abolished facial nerve function the judgments of the ENT physician and the surgeon agreed with the patient's own evaluation.
The growth rate of acoustic tumors varies widely. An immunohistochemical study with Ki-67 monoclonal antibody was performed on a random sample of 21 acoustic neuromas. The tumors belonged to 2 well-defined groups: 1 with a short duration of preoperative symptoms (< 1 year) and 1 with a long duration of preoperative symptoms (> 5 years). The tumors were of small to medium size (7 to 27 mm), and no large, cystic, or Recklinghausen tumors were included. The tumor proliferative fraction expressed by monoclonal antibody Ki-67 was determined. The results revealed a significant relation between the tumor proliferative fraction and symptom duration. Tumors with a high proliferative status had a short preoperative symptom duration, while tumors with a low proliferative status had a long symptom duration. The clinical implications of these results are discussed.
Tumor configuration and attenuation on CT scan with contrast enhancement or gadolinium-DTPA-enhanced MR depends upon tumor histology. Various elements are responsible for the density on CT or MR, e.g. blood vessels, fatty tissue, connective tissue, calcium, necrotic tissue, hemorrhage and intra- or extratumoral cyst formation. In a series of 571 acoustic neuromas we found 23 cystic tumors. The diagnosis was based on neuro-imaging examination, confirmed at surgery and finally verified histologically. Eight tumors with small or large cysts were diagnosed by CT or MR scan as intratumoral, and 15 with large cysts were diagnosed as extratumoral. We found a good correlation between the histology of cystic acoustic neuromas and the CT or MR scans. The tumors were predominantly hypodense, corresponding to the cystic areas, but also iso- or hyperdense areas were observed, corresponding to other tissue types. Antoni type B tissue and xanthomatous areas were found in all 23 cases.
A survey of the management of acoustic neuromas in the broadest sense is given. The epidemiology and pathogenesis is described. The clinical development may take any imaginable course, and even though a slowly progressing unilateral hearing impairment, of the sensorineural type, is the main pattern of presentation, it is stressed that any type of symptom could appear in an acoustic neuroma patient. In order to make an early diagnosis a high index of suspicion must be the basic principle, with all patients with unilateral symptoms, not only hearing deficits, being suspected of suffering from acoustic neuromas until proven otherwise. All patients with hearing better than 70-80 dB should be subjected to ABR, and if there is any doubt about the normality of the response, the patient should proceed to MRI. Patients with poor hearing should go directly to MRI. The advantages and disadvantages of the different surgical approaches are described and an electric treatment algorithm is outlined: 1) All tumors measuring 25 mm or more on MRI are operated via the translabyrinthine approach. 2) All patients with PTA poorer than 30 dB, and SDS poorer then 70% are operated via the translabyrinthine approach. 3) Tumors less than 10 mm extrameatally, and PTA better than 30 dB and SDS better then 70% are removed via the middle fossa route. 4) Tumors measuring 10-25 mm and PTA better than 30 dB and SDS better than 70% are removed via the suboccipital route.
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The medial acoustic neuroma, a new clinical entity, is defined as an extrameatal tumor without tumor mass laterally in the internal acoustic meatus. During a 12-year period in Denmark, in a prospective analysis of 400 acoustic neuromas on which surgery was performed by the translabyrinthine approach, 48 tumors (12%) were medial tumors, corresponding to an incidence of 0.8 tumors per million inhabitants per year. Analysis of the symptoms and results showed that medial tumors are generally larger with more severe involvement of the cerebellum, the trigeminal nerve, and the brain stem, compared with the 352 nonmedial tumors. Because of its onset in the medial part of the vestibular nerve, the tumor may grow silently and to a considerable size without any widening of the internal auditory canal and with relatively good hearing. Meaningful hearing preservation is impossible in medial tumors, because the smallest medial tumor (subject's hearing, 40 dB or better) measured 3 cm, and the majority of tumors are giant tumors.
In 35 patients with absence of the stapedial arch, with a history of radical surgery, and without ossicles, the head of an allograft stapes was placed on the patients' footplates and an allograft incus body on the top of this. The long-term results of this assembly, judging by different methods of analysis, are still somewhat better than those of 98 ears with approximately the same pathologic condition treated by an allograft incus as the columella between the footplate and fascia. The allograft stapes-incus assembly is an alternative method to the commonly used incudal columella. The allograft stapes has not been resorbed to a significant degree during the years after surgery.
This investigation was performed to describe some aspects of the quality of life in subjects after translabyrinthine removal of an acoustic neuroma, resulting in unilateral total deafness. Two hundred ninety-three subjects who had been operated on during 1976 through 1990 and who were living outside the Copenhagen (Denmark) City and County received a postal questionnaire, to which 93% (n = 273) responded: 118 men and 155 women with a median age of 58 years (range, 18 to 81 years). The median observation period from surgery to the questionnaire was 6 years (range, 6 months to 14 years), and the median age at operation was 52 years (range, 15 to 76 years). Among the subjects, 22% had received postoperative hearing rehabilitation with various types of hearing aids in the ear not operated on. In 62%, tinnitus was experienced in the ear with tumor before surgery, and at the time of the questionnaire, 49% experienced tinnitus in the ear operated on. Half a year after surgery, 56% still experienced dizziness. Sixty-four percent reported damage to the facial nerve in relationship to the operation. At the time of the questionnaire, 12% indicated a total loss of facial nerve function. No vocational consequences were found in 74% after surgery. Information concerning different symptoms related to surgery was insufficient in 29%, while the quality of information in relation to surgery was more satisfying. In conclusion, the study demonstrates that deafness, dysequilibrium, and reduced facial nerve function caused the most severe problems. Improved information to patients before surgery may reduce the frequency of negative experiences.
The relationship between temporal bone pneumatization and the location of the lateral sinus and length of the mastoid process was investigated in 60 fresh frozen adult temporal bones, by plain X-rays, computed tomography and surgical dissection including otomicroscopic findings. Temporal bone pneumatization was classified as small, moderate and large. After drilling, the shortest distances between the middle fossa dura and mastoid tip representing the mastoid length and between the sigmoid sinus and posterior border of external auditory canal were measured and compared to the degree of pneumatization. The distances in the specimens with pathological eardrum and adhesions in the middle ear were compared to the ones without gross pathology. The length of mastoid process was significantly shorter in specimens with small pneumatization than those with large (Mann Whitney P less than 0.001). The specimens with a pathological eardrum and middle ear adhesions had a significantly shorter mastoid length than those without gross pathology. There was no significant difference between degree of pneumatization and the shortest distance between sigmoid sinus and external auditory canal (Mann Whitney P greater than 0.05). It is demonstrated that the 'under-developed' mastoid process can be a consequence of hampered pneumatization.
In our series of 525 patients operated on for acoustic neuroma, there were three false-positive computed tomography findings resulting in unnecessary surgery. The histories and results of laboratory investigations and surgery are presented. Discussion of the outcome had gadolinium-enhanced magnetic resonance imaging been performed is presented.
Histopathological characteristics of 20 ear herodion polyps with a certain localisation and a well-known underlying pathological process were studied in order to elucidate the pathogenesis of ear mucosal polyp formation. Only 12 of the polyps were covered with epithelium; either a squamous keratinized epithelium or a cylindrical epithelium. Three polyps were covered with cylindrical and squamous keratinized epithelium. Incipient gland formation was seen and glands were only found in 35% of the polyps. It seems possible that the polyp is a local newly formed process and may have the aim of catching, eliminating and digesting bacteria and dead cells.
Forty-six consecutive video-recorded translabyrinthine operations at Gentofte Hospital, for tumors of 5 to 25 mm, were investigated for possible damage to the facial nerve from cauterization, suction, stretching, pushing, and other instrumental trauma at the following regions: fundus, internal meatus, porus, cerebellopontine angle, and brain stem. House-Brackmann grading of the postoperative facial nerve function was determined from the patient records for the 1st, 3rd, and 10th days and 3 months and 6 months postoperatively, as well as the final status. Suction on the nerve seems to be the most important factor for perioperative facial nerve damage. The most common site of damage was the porus region. This investigation shows thermic drilling lesions to be very relevant. There was no correlation between the degree and character of damage and the postoperative facial nerve function. In eight patients we cannot explain the postoperative facial palsy.