In Vivo Visualization of Endolymphatic Hydrops in Guinea Pigs: Magnetic Resonance Imaging Evaluation at 4.7 Tesla

In order to find out whether it is possible to visualize experimental endolymphatic hydrops in the cochlea with magnetic resonance imaging (MRI) at 4.7 T, we used 11 guinea pigs. Five normal guinea pigs were used as controls. Early manifestation of endolymphatic hydrops was evaluated in endolymphatic sac (ES)-intact animals (n = 6), and advanced manifestation in ES-damaged animals (n = 5) by means of MRI with gadolinium-diethylenetriaminepentaacetate-bismethylamide (Gd-DTPA-BMA) contrast agent. Hearing was tested with electrocochleography. The surface area of 3 partitions of the cochlea was used to quantify endolymphatic hydrops. The fine structure of the 3 partitions of the cochlea was visualized with MRI in all animals, as Gd-DTPA-BMA appeared mainly in the scala tympani and scala vestibuli. As early as 5 days after endolymphatic sac surgery, endolymphatic hydrops started to appear as visualized by MRI and also verified with histology. Severe damage to the inner ear barrier with Gd-DTPA-BMA leakage into the scala media was detected with MRI in 1 ES-damaged animal that had a 60-dB hearing loss. To conclude, endolymphatic hydrops can be visualized with high-resolution MRI by means of Gd-DTPA-BMA, and it is possible to quantify the extent of endolymphatic hydrops. Damage to the inner ear barrier or possible rupture of membranes can be shown with the assistance of Gd-DTPA-BMA.

Cochlear otospongiosis etiology, diagnosis and therapeutic implications

First, the authors discuss the most valuable way to correlate specific morphological changes encountered in cochlear otospongiosis with sensorineural hearing loss. They think that biochemical factors may be responsible for this association of cochlear otospongiosis and histopathologic changes, and they explain their enzymatic concept resulting from experimental findings and cyto-clinical relationship. Second, the authors analyze clinical, audiometric and X-Rays investigations enabling the diagnosis of cochlear otospongiosis, in its pure pereceptive form as well as in the perceptive component added to the conductive loss in far-advanced mixed audiometric types in surgical otospongiosis. They present two typical cases of cochlear otospongiosis: one combines clinical history, audiometric test and post mortem investigations;-the other shows the passage from a pure cochlear otospongiosis to a secondary stapedial fixation, ten years later, thus confirming by audiometric data and by stapedectomy the otospongiotic etiology of this previous pure sensorineural loss. Finally, they insist upon the great interest of establishing an early diagnosis in cochlear otospongiosis on account of its therapeutic implication, particularly from the enzymatic point of view.

Hearing outcomes after mobile ear surgery for chronic otitis media in Greenland

OBJECTIVES

Chronic otitis media (COM) with hearing loss (HL) occurs frequently in many populations with limited access to specialized treatment. This article reports on the hearing outcomes following mobile ear surgery in Greenland.

STUDY DESIGN

The study was longitudinal and prospective with pre- and post-operative followup data compiled at 1- and 2-year intervals.

METHODS

Selection criterion included individuals with COM with or without suppuration (CSOM) and with associated HL. Hearing tests were obtained by using a simple air-conduction (AC) audiometry. The median age of the 274 participants was 27 years (8-60 years), and 45% were males. Sixty-one percent had COM and 34% had CSOM. Myringoplasty or tympanoplasty type I was performed in 88% of the cases.

RESULTS

The median pre-operative AC pure-tone average was 38 dB. The follow-up rate was 75% and 61% at 1- and 2-years. Hearing gain was found in 78% at both follow-ups and was > or = 10 dB in 62% and 56%, respectively. The median hearing gain was 15 dB and 12 dB, respectively. Independent predictors of hearing gain were pre-operative tympanic membrane atrophy and closure of perforations.

CONCLUSIONS

Long-term hearing gain can be achieved with mobile ear surgery and this, in addition to tympanic membrane closure, is important for hearing rehabilitation in populations with poor access to health care.

Cancer of the external auditory canal and middle ear in Denmark from 1992 to 2001

BACKGROUND

In the context of the Danish Head and Neck Cancer Group, nationwide material from 1992-2001 was analyzed to study the extent and nature of the disease, evaluate treatment, compare staging systems, and examine prognosis and survival.

METHODS

Review of 68 consecutive cases: 47 squamous cell carcinoma, 10 basal cell carcinoma, and 11 other histologies. Moody (modified Pittsburgh) stages were T1 (26), T2 (9), T3 (8), T4 (23), Tx (2). Sixty-four patients were treated with curative intent: 24 primary radiotherapy, 18 primary surgery, and 22 combined. Surgery was limited to tumor excision and mastoidectomy and in 1 case temporal bone excision.

RESULTS

Twenty-seven of 28 recurrences involved primary site. Kaplan-Meier analysis showed 5-year locoregional control of 48%, disease-specific survival 57%, and overall survival 44%.

CONCLUSION

This nationwide study confirmed that local failure is the main problem, and future improvements should focus on more aggressive local treatment.

Outcome of mobile ear surgery for chronic otitis media in remote areas

OBJECTIVES

The Inuit of Greenland, Canada and Alaska suffer from chronic otitis media (COM). In Greenland these patients used to be referred to Denmark for ear surgery. This was expensive and unsatisfactory, and the results were poor. A mobile ear surgery project was developed.

DESIGN

The study is longitudinal and prospective with follow-up.

SUBJECTS AND METHODS

The 274 patients were selected according to severity of COM and hearing loss. Only air conduction (AC) audiometry was obtained. Median age was 27 years and 55% were females.

RESULTS

Closure rates at three weeks, one year, and two years were 67 percent, 72 percent, and 76 percent, respectively. Median AC pure tone average improvement was 15 dB and 12 dB after one year and two years, and 73 percent and 67 percent were satisfied. Outcome was associated with quality of the surgical skills (P < 0.002). We found marked spontaneous fluctuations between the follow-ups.

CONCLUSION

The results of mobile ear surgery in Greenland are acceptable. Mobile ear surgery may be implemented in areas with limited access to health care, eg, in developing countries.

Dynamic bone studies of the labyrinthine capsule in relation to otosclerosis

The pathological perilabyrinthine bone remodelling of otosclerosis is associated with a genetic predisposition and triggered by mechanisms so far unknown. A proposed viral aetiology of otosclerosis originates from a similar concept of Paget's disease. However, at present, it is not clear why a virus should cause otosclerosis, confined to the bony otic capsule with no effects on the general skeleton in some patients, and systemic Paget's disease with only occasional involvement of the bony otic capsule in others. Moreover, the extent and distribution of pathological bone remodelling is different in Paget's disease of the temporal bone and in otosclerosis. Bone resorption and consequently bone remodelling which turns over the general skeleton at a rate of 10% per year is normally highly restricted in perilabyrinthine bone to a minimum of 0.13% per year except in otosclerosis, and systemic remodelling rates are normal even in otosclerotic patients. This suggests the existence of a local inner ear mechanism in control of capsular remodelling activity, which is either overruled, bypassed or most likely defective in otosclerosis, no matter what may have triggered the disease process. We present experimental data related to this mechanism, which may offer a truly local pathogenetic factor in otosclerosis.

Acute otitis media and season of birth

INTRODUCTION

This study examines the question whether season of birth is associated with acute otitis media (AOM) and recurrent AOM (rAOM) and whether season of birth is associated with early age of AOM onset.

METHODS

This was done in a population-based survey of 591 unselected Greenlandic children aged 3-5 and 8 years, living in the two largest towns in Greenland. The overall attendance rate was 86%. Information of AOM episodes was obtained from the parents and cross-checked in medical records available for 95% of the children. In total, 67% reported AOM at least once and 30% of those had rAOM.

RESULTS

According to season of birth, the frequency of history of AOM in general varied between 63% and 70% lowest for birth in the autumn and highest for birth in the spring but without any significant statistical difference (p=0.51). The similar variation in rAOM according to season of birth was between 21% and 35%, highest for children born in autumn and winter and lowest for children born in the spring (p=0.09). Additionally, there was no difference in age at onset of the first AOM episode according to season of birth. However, AOM children born in the summer and autumn periods have a significantly higher relative risk (RR=1.44, CI=1.04-1.99) of attracting rAOM than AOM children born in the winter and spring periods. This may be due to a higher risk of being quickly reinfected in the late autumn and winter period with another episode of upper respiratory tract infection.

CONCLUSION

Season of birth do not seem to be a predictor of AOM episodes or early onset of AOM but children born in the summer and autumn periods who attracts AOM have a higher risk of developing rAOM.

In vivo observation of dynamic perilymph formation using 4.7 T MRI with gadolinium as a tracer

OBJECTIVE

To investigate the pharmacokinetics of gadolinium in the perilymphatic fluid spaces of the cochlea in vivo using high-resolution MRI to obtain information concerning perilymph formation.

MATERIAL AND METHODS

A Bruker Biospec Avance 47/40 experimental MRI system with a magnetic field strength of 4.7 T was used. Anesthetized pigmented guinea pigs were injected with the contrast agent Gd-diethylenetriaminepentaacetic acid-bismethylamide and placed in the magnet. The signal intensity of Gd in the tissues was used as a biomarker for dynamic changes in the perilymphatic fluid.

RESULTS

The most rapid uptake of Gd in the perilymphatic fluid spaces occurred in the lower part of the modiolus, followed by the second turn of the scala tympani. Within the scala tympani, the distribution of Gd in the basal turn was significantly lower than that in the other turns. Destruction of the cochlear aqueduct was followed by an increase in Gd uptake in the perilymph instead of a reduction.

CONCLUSIONS

These findings offer further evidence that the pervasive perilymphatic fluid derives from the cochlear blood supply via the cochlear glomeruli, which are in close proximity to the scala tympani within the modiolus, and the capillary in the spiral ligament. Cerebrospinal fluid communicates with perilymph via the cochlear aqueduct but is not the main source of perilymph. These findings are of relevance to the treatment of inner ear diseases, as well as to our understanding of the flow and source of perilymphatic fluid.

Comparison of the protective efficacy of neurotrophins and antioxidants for vibration-induced trauma

BACKGROUND

Patients undergoing temporal bone surgery or subjects working with vibrating tools may develop vibration-induced hearing loss (VHL). The aim of this study was to characterize the effects of pretreatment with N-acetylcysteine (NAC) or the neurotrophic factors, brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF), on VHL in an animal model.

METHODS

Trauma to the cochlea was created with a vibrating probe placed on the bone of the external ear canal. BDNF and CNTF(Ax1) were delivered into the cochlea with mini-osmotic pumps. NAC was delivered into the cochlea by round window membrane (RWM) injection, by RWM permeation, or by oral administration. Hearing was evaluated with electrocochleography (ECoG).

RESULTS

For control animals, vibration resulted in an average immediate threshold shift of 42 +/- 26 dB. NAC provided no protective benefit in animals subjected to VHL, regardless of the delivery method, with average threshold shifts varying from 38 to 56 dB across groups. NAC injection through the round window membrane was toxic, causing a ECoG threshold shift of >25 dB. In BDNF+CNTF(Ax1)-treated animals, immediate hearing loss was similar to that in control animals. There was a trend of threshold recovery by 1 day after vibration; however, the improvement was not statistically significant, nor was there a significant difference in 1-day thresholds across groups.

CONCLUSIONS

Local infusion of BDNF and CNTF(Ax1) may enhance the rate of recovery from VHL, compared to control animals. In contrast, NAC had no effect on VHL, and when delivered by RWM injection, was actually toxic to the inner ear.

The endolymphatic sac: a scanning and transmission electron microscopy study

A recent investigation has suggested that the chief cells of the endolymphatic sac produce an endogenous inhibitor of sodium resorption in the kidneys, tentatively named saccin. In the current study, the ultrastructure of the endolymphatic sac and in particular the chief cells are described to demonstrate that this organ fulfils the morphological criteria of a potential endocrine gland. Accordingly, the chief cells are shown to exhibit all the organelles and characteristics of cells that simultaneously synthesize, secrete, absorb and digest proteins.

Demonstration of intravital microfissures in undecalcified plastic-embedded temporal bones with the prestaining technique

Microfissures in the human otic capsule have been observed since the start of the century, but it was Otto Mayer, in 1930, who first realized that some of them were of intravital origin and not just processing artifacts. Since then, a small number of publications, based on decalcified temporal bones, have mostly confirmed his findings. With the introduction by Frost in the late 1950s of the undecalcified bone technique and the bulk staining technique for peripheral bones, a method was developed and refined for identifying even very small intravital microfissures (microdamage). Bulk staining of undecalcified otic capsules has not yet been used to verify the findings from the previous decalcified specimens. The present report presents our experience with the pertinent techniques, and suggests modifications and shortcuts pertinent to temporal bone research. Both large and tiny microfissures of intravital genesis are demonstrable within bulk-stained undecalcified human otic capsules. The importance of microfissures in the petrous bone in the causation of otosclerosis and perilymphatic leakage has long been discussed, and the present techniques may advance our understanding of these pathological conditions

Predilection of otosclerotic foci related to the bone turnover in the otic capsule

Using multiple fluorochrome tagging of eight mongrel dogs and a newly established methodology of measuring bone turnover (BTO) in the otic capsule, it has previously been demonstrated that BTO in the canine otic capsule is highly reduced close to the perilymphatic spaces (PLS) compared to the normal level of BTO in the periphery. Reanalysis of these data shows that this inhibition of BTO is far more pronounced around the cochlea and vestibule than around the semicircular canals. Similar tendencies are seen for the numerical density and mean label area of the bone remodelling units. With increasing distance to the PLS, these patterns are weakened, but still recognizable. In otosclerosis, foci of abnormal bone deposition are particularly frequent around the oval and round windows and in the cochlear capsule, i.e. where inhibition of bone remodelling is most prominent. A surpassing (or failure) of this pronounced inhibition must precede the tumultuous but delimited osteogenesis of otosclerosis. Otosclerosis may be a deviation of the normal BTO process in an osteometabolically abnormal site, perhaps initiated as an osteogenetic response to abnormal stress exposure.

Database developed to record and evaluate computer aided endonasal surgery results

Computer aided surgery has been used in the Department of Otolaryngology--Head & Neck Surgery, Rigshospitalet, Copenhagen since October 1998, and is now a regular supplement to conventional functional endonasal sinus surgery (FESS) and management of anterior skull base lesions. This technique was designed to enhance surgical precision and thoroughness and to reduce complications. Since this is a new technique, the clinical findings and surgical outcome are prospectively collected in a database. Results for conventional FESS are entered in the same database for comparison. The aim of this study is to present a standardized Danish database.

Cystic hygroma of the head and neck--a long-term follow-up of 44 cases

Cystic hygroma of the neck is a relatively rare congenital malformation usually diagnosed during the first years of infancy. Complete surgical extirpation may be impossible without sacrificing important neurovascular structures. This paper reports the long-term outcome of surgical treatment during a 35-year period. A follow-up examination of 44 patients (24 males and 20 females) treated in our departments during the last 35 years was performed. Median age at first operation was 1.5 years (0-28 years) The observation period ranged between 1 and 36 years, median 16.2 years. Indications for operation were space occupying lesion, haemorrhage, dysphagia, difficulties in pronunciation or breathing and infection or nerve lesions. Fifty percent of the patients revealed residual or recurrent hygroma at the time of follow-up. Forty-four percent suffered from impaired speech, food intake, breathing or swallowing. Thirty-six percent were cosmetically bothered, and only 11% reported reduced quality of life. A significant correlation was noted between the extension of the lesion and (i) the number of operations performed and (ii) the rate of recurrent or residual hygroma. The rate of residual or recurrent hygroma was statistically higher for the suprahyoid lesions compared with the infrahyoid lesions. The localization and extent of the lesion is related to the surgical outcome. Surgical intervention should be centralized and should be considered carefully. Neurovascular structures should not be damaged in an attempt to effect complete removal. The above-mentioned results lead to a search for a new therapeutic modality, and the authors have recently taken up the Japanese way of treating hygromas by intralesional injection of OK-432. The first two patients treated by this technique had total regression of the lesion, and the method seems to be promising as an alternative to surgery.

Recognition of basic fuchsin prestained microfissures of intravital origin with fluorescence microscopy: validation of a shortcut

For 70 years it has been suspected that not all microfissures in histological bone sections are artifacts, but that some are provoked in vivo through repetitive stress. The development of undecalcified bone techniques and of the bulk staining technique has established a method for demonstrating the existence of intravital cracks and enhanced the discrimination towards artifactual microfissures in the load-bearing skeleton. Recently the presence of intravital microfissures has also been ascertained in temporal bones by these techniques. Due to the fluorescent properties of basic fuchsin it is possible to use epifluorescence microscopy for analysis of microfissures after bulk staining with basic fuchsin. This provides a more steady microscopic background and a sharper delineation of surface level structures since no projection from lower levels interfere. Artifactual cracks, which in transmitted light microscopy may look like darkly stained intravital microfissures due to refraction phenomena, become invisible or colorless. Epifluorescence microscopy enhances the detection of both smaller and larger prestained intravital microfissures, and leaves only a minor part of the cracks without certain categorization. The epifluorescence mode of analysis has the further advantage of being independent of slice thickness, making feasible whole-specimen analysis by serial stepwise grinding. The present study shows that the number and the length of microfissures in the human otic capsule, counted and measured under the epifluorescence microscope, equals numerically the findings in light microscopy, enabling the routine use of this mode of analysis. This may prove to be of particular value in the research into the etiology and pathogenesis of otosclerosis as well as perilymphatic fistulae.

Sensorineural hearing loss after vibration: an animal model for evaluating prevention and treatment of inner ear hearing loss

Sensorineural hearing loss following a variety of acoustic trauma, including middle ear surgery, is well known. Current literature, which points to the deleterious influence of noise on the inner ear during surgery, has yet to assess the influence of vibration generated by the burr. The purpose of the study reported here was to establish an animal model that mimics drilling and can be used to explore methods of hearing loss prevention and treatment. A specially developed electromagnetic vibrator was calibrated and used in 59 guinea pigs to induce hearing loss. Both young and old guinea pigs were used. The bony external ear canal of guinea pigs were exposed to vibration or sound of varying duration and intensity. The vibration of the temporal bone and noise level in the middle ear were measured. Electrocochleography was recorded to evaluate the hearing loss. Among the young animals, 90% developed a significant threshold shift (TS > 20 dB), when vibrated with 250 Hz at an intensity of 6.2 m/s2 for 15 min. An average of 42 dB TS was observed. With 10 min exposure 63% showed a TS. The older animals vibrated for 5 min developed the same TS (mean TS 34 dB) as the young animals when vibrated for 10 min. The vibration-induced TS showed no recovery within 3 days of observation. In the contralateral ear 4 out of 5 animals showed TS > 20 dB. When exposed to sound levels exceeding the vibration-generated sound in the middle ear (119 dB at 250 Hz) only 2 out of II animals (18%) showed TS. The frequency of TS and level of TS were significantly greater in the vibrated animals than in sound-only exposed animals (p < 0.01). The degree of vibration-induced TS in the present animal model could be controlled by vibration intensity and duration. The older animals were more susceptible to vibration-induced inner-ear damage than younger animals. This model will be used in further studies to find methods for prevention and treatment of hearing loss during ear surgery.

[Surgical treatment of otosclerosis with argon laser]

OBJECTIVES

Argon laser stapedotomy is a new modality for the treatment of otosclerosis. The first results obtained in Denmark are reported.

MATERIALS AND METHODS

A retrospective follow-up study was undertaken to evaluate the results of argon laser stapedotomy which was introduced in 1991 at the department of Otolaryngology, Rigshospitalet, Copenhagen. The results are based on 85 consecutive primary stapedotomy operations with argon laser in 76 patients during the period January 1, 1991 to June 30, 1996. Mean follow-up was 16.6 months (6-60).

RESULTS

The postoperative air-bone gap was closed within 10 dB or less in 83% of the operations and in 20 dB or less in 98%. The mean speech reception threshold (SRT) was 48 dB preoperatively. All patients had an improved SRT after the operation, with a mean value of 23 dB. At 4000 Hz and 8000 Hz, 89% and 65% of the patients had maintained or improved their hearing. No patient developed profound sensorineural hearing loss or anacusis after the operation. Only one patient developed symptoms of a temporary perilymphatic fistula.

CONCLUSION

Argon laser stapedotomy is a safe technique. Its complications are fewer and not as serious as conventional methods. In addition, the achieved hearing results are better, and thus it is a good example of "minimal invasive high success surgery".

Quantification of osteoclastic resorption of the bovine otic capsule in vitro by an enzyme-linked immunosorbent assay

The bony shell surrounding the inner ear is known to have a very pronounced centripetal inhibition of remodelling in vivo, with almost no bone turnover immediately adjacent to the perilymphatic spaces and a gradually increasing turnover rate towards outer parts of the bony otic capsule. By the use of in vitro markers of bone resorption, including an enzyme-linked immunosorbent assay for quantification of type I collagen degradation and a colorimetric enzyme assay for quantification of osteoclast tartrate-resistant acid phosphatase activity, this study demonstrates that there are no ex vivo differences in bone matrix resorption between the inner and outer parts of the otic capsule when exposed to seeded osteoclasts from rabbits. Thus, the unique spatial distribution of perilabyrinthine bone turnover is not caused by a shift in resorbability from inner to outer capsular bone that is due to inherent bone quality differences particular to these bone compartments. More likely, the sustained action of some intravital 'field force', originating from the inner ear spaces, is responsible for the unique spatial distribution of the otic capsular bone turnover found in vivo. Though the character of this force is not yet defined, it is appealing to relate it to the large electromagnetic potential gradient present in the inner ear.

Experience in qualitative and quantitative FDG PET in follow-up of patients with suspected recurrence from head and neck cancer

We evaluated positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in the detection of recurrent head and neck cancer, and compared visual and quantitative interpretation of PET images for their accuracy in the identification of tumour recurrence. Sixty-two FDG PET studies were performed in 56 patients having a total of 81 lesions, which were clinically suspected for recurrent carcinoma of the head and neck. The PET images were interpreted visually, and tracer uptake was quantitated as the standardised uptake value adjusted to body weight (SUV). Sensitivity of visual interpretation of the PET images for the presence of malignancy ranged from 84 to 95%, and specificity from 84 to 93%, respectively, depending on the selected scheme for grading of the lesions. Malignant lesions accumulated significantly more FDG than the benign ones (the median SUVs were 6.8 and 3.3, respectively, P<0.001). However, there was a wide overlap of the FDG uptake values between these two groups. Hence, the highest accuracy of quantitative analysis in correct identification of tumour recurrence (75% at Receiver Operating Curve analysis) was inferior to that of visual analysis (89%). FDG PET is feasible for the detection of recurrent head and neck cancer. Although quantitation of FDG uptake using SUV shows significantly higher tracer concentrations for malignant than benign lesions, the wide overlap of individual SUVs between these two groups is a serious concern in diagnostic evaluation. Therefore, in clinical practice it may be preferable to identify the presence of tumour recurrence within this patient group by qualitative interpretation of the PET images.

Estimation of volume referent bone turnover in the otic capsule after sequential point labeling

Using fluorochrome labeling and a newly validated method for bone turnover estimation, we determined absolute values for canine perilabyrinthine bone remodeling. The overall capsular bone turnover was found to be 2.1% per year, compared to 13.9% per year for the neighboring cranial bones and 7.4% per year for the humerus compacta. This gross 2.1% per year conceals a vast range, from 0.13% per year for the innermost perilymphatic zone, through a centrifugal increment toward 8% to 10% per year in the periphery. The underlying individual bone remodeling units exhibit a similar centrifugal pattern in numerical density and size. These findings indicate an inhibition of remodeling, seemingly emanating from the perilymphatic spaces, and affecting both the activation of osteoclasts and the extent of resorption by the osteoclasts. These values satisfactorily explain the preservation of such fetal remnants as the globuli ossei, the interglobular spaces, and the skein bone. In humans, local ineffective inhibition of bone resorption may play a role in the initiation of otosclerosis.

Acute otitis media and sociomedical risk factors among unselected children in Greenland

OBJECTIVE

To describe the sociomedical risk factors associated with episodes of acute otitis media (AOM), recurrent AOM (rAOM), and chronic otitis media (COM) in Greenlandic children and especially to point out children at high risk of rAOM (defined as > 5 AOM episodes since birth) and COM which are prevalent among Inuit children all over the Arctic.

METHODS

The study design was cross-sectional and included 740 unselected children, 3, 4, 5, and 8-years-old, living in two major Greenlandic towns, Nuuk and Sisimiut. All children were otologically examined and the parents answered a questionnaire containing sociomedical variables including ethnicity, family history of OM, housing, insulation, crowding, daycare, passive cigarette smoking, breast feeding, type of diet, allergy, and chronic diseases. Historical data were cross-checked in medical records which also formed the basis for the drop-out analyses. Statistical analyses included frequency tests, calculation of odds ratio (OR), and multiple logistic regression.

RESULTS

The attendance rate was 86%. Former episode of AOM was reported by 2/3 of the children, rAOM by 20%, and COM by 9%. The following variables were found significantly more often in children with AOM by simple frequency testing: Parental (OR = 1.83), sibling (OR = 1.62), and parental plus sibling (OR = 2.56) history of OM, crowding (OR = 5.55), long period of exclusive breast feeding ( > 4 months) (OR = 2.47), and recent acute disease (P = 0.034). The following variables were found significantly more often in children with rAOM or COM by simple frequency testing: Parental history of OM (OR = 1.60; OR = 2.11, respectively) and no recall of breast feeding (P = 0.005; P = 0.003, respectively). Also, COM was found significantly more often in children with two Greenlandic parents (OR = 3.07). A multiple logistic regression test denoted only parental history of OM (OR = 1.82) and long period of exclusive breast feeding (OR = 1.14) as significant predictors of AOM.

CONCLUSIONS

Many of the risk factors usually associated with AOM could not be confirmed as risk factors in this survey. Parental history of OM and long period of exclusive breast feeding were the strongest factors associated with AOM in Greenlandic children and ethnicity was associated with COM. However, the study confirms that AOM is a multifactorial disease determined by a number of genetic and environmental factors.

Respiratory tract infections in Greenlandic children: a prospective cohort study

Respiratory tract infections in children, measured in terms of both morbidity and mortality, represent a major health problem in Greenland. In particular, otitis media is highly prevalent, and is characterized by early onset and a high degree of chronicity. There is, however, little knowledge about the epidemiology of respiratory tract infections in Greenland. In the spring of 1996, a prospective study of such infections in infants and children was initiated in Sisimiut, West Greenland. The main objectives of the study are to describe the epidemiology of respiratory tract infections in children under four years of age, to estimate the impact of these diseases on short- and long-term morbidity, and to identify risk factors for transmission and clinical severity. An open cohort of children in Sisimiut will be formed, including all resident children below three years of age at the beginning of the study, as well as all children born in the following two-year period: in total approximately 600 children. During two years, these children will be followed closely, including registration of episodes of respiratory tract infections. Furthermore, growth will be measured and microbiological samples obtained.

The endolymphatic sac, a potential endocrine gland?

A previous investigation indicated that the chief cells of the endolymphatic sac produce an endogenous inhibitor of sodium re-absorption in the kidneys, which has tentatively been named "saccin". In this study, the ultrastructure of the endolymphatic sac and in particular the chief cells is described, demonstrating that this organ fulfils the morphological criteria of a potential endocrine gland. Accordingly, the chief cells are shown to exhibit all the organelles and characteristics of cells that simultaneously synthesize, secrete, absorb and digest proteins.

Acute otitis media and age at onset among children in Greenland

This survey examines the age at onset of acute otitis media (AOM) in 591 unselected Greenlandic children aged 3, 4, 5 and 8 years from the two largest towns in Greenland. The attendance rate was 86%. Parental information about episodes of AOM was cross-checked in medical records, which were available for 95% of the children. AOM was defined as episodes with earache, otorrhoea or previous treatment for AOM, with written otoscopic evidence of AOM resulting in treatment with weak analgetics or antibiotics. Recurrent AOM (rAOM) was defined as > or = 5 AOM episodes since birth. In total, 66% of the children had experienced AOM at least once. Of all children, 40% had AOM during the first year of life. Median age of the first episode was 10 months (range: 1-84 months), and there was no sex difference. Children between 7 and 12 months of age were at highest risk of AOM. Children with rAOM had their first AOM episode at a significantly younger age than children with < 5 AOM episodes (median: 7 months, range: 2-48 months). In addition, 83% of children with rAOM had their first AOM episode before 12 months of age compared with 53% of children with < 5 episodes (p < 0.0001). The relative risk of rAOM was eight times greater if the first episode of AOM occurred before six months of age compared to more than 24 months of age. Thirty-five percent of children with rAOM had chronic otitis media as well, compared to only 4% of children with < 5 AOM episodes. We conclude that early onset of AOM (before one year of age) occurs frequently in Greenlandic children compared to others, and a high proportion of these children develop rAOM.

An aggressive and invasive growth of juvenile papillomas involving the total respiratory tract

A malignant course of juvenile laryngeal papillomatosis has rarely been reported. In the present case the patient had had laryngeal papillomas since the age of three years. The papillomas gradually spread to the entire respiratory system, and during 30 years the patient was operated on more than 80 times. At present an invasive tumour spreading from the tongue into the parapharyngeal space, extending to the cranial base, has been demonstrated by magnetic resonance imaging (MRI). Intralesional therapy with Cidofovir, a promising antiviral drug against human papillomavirus (HPV) infection, was started with some clinical effect, although only on the superficial tumour growth. Histology of removed tumour tissue has demonstrated a mixture of exophytic and inverted growth pattern, and has mainly been interpreted as benign, in spite of a focally high mitotic index and an intermittent lack of maturation in the epithelium. In the most recent biopsies a verrucous carcinoma has been diagnosed. Expression of p53 was noted to increase in papillomas with time. All samples have been shown to harbour HPV 11, but no other HPV types.

Volume-referent bone turnover estimated from the interlabel area fraction after sequential labeling

In the compact bony otic capsule remodeling is low, and bone remodeling units are distributed centrifugally in relation to inner ear tissues and spaces. Fluorochrome-labeled bone remodeling units are scarce, abortive, and tortuous with no uniform direction of movement. This study presents a method for the estimation of volume-referent bone turnover based on measurements of the fractional area between labels after sequential labeling with osteofluorochromes. The applicability of this method is tested against a classical quantification method in undecalcified cortical specimens from the canine humerus, where both methods can be used. The estimate of bone turnover derived from the new sequential labeling in eight dogs is 7.4% (SEM 2.1%) per year and the classic estimate derived from calculations of the formative osteonal area and the formative period yields 6.9% (SEM 2.1%) per year. Agreement is sufficient to justify future measurements of absolute bone turnover in sequentially labeled perilabyrinthine bone.

Prevalence of otitis media in a survey of 591 unselected Greenlandic children

In an unselected survey in two Greenlandic towns, 591 children were examined to study the prevalence of otitis media (OM). The attendance rate in Nuuk was 80%, while 93% participated in Sisimiut. The children were three-, four-, five- and eight-years-old and represented 18% of children in these age groups in all Greenland. In total, 51.7% in Nuuk and 54.1% in Sisimiut presented pathologic middle ear affections ranging from slight to severe. The prevalence rates of chronic OM (COM) were 6.8% in Nuuk and 11.7% in Sisimiut (P = 0.055) but without significant age or sex difference. The acute OM point prevalence rate was between 1.5% and 0.4%. The prevalence rate of middle ear effusion (MEE) was between 23.0% and 28.2%. Secretory OM was significantly more prevalent in the younger age groups. The odds ratio of having COM was significantly higher in children with two Greenlandic born parents (3.07) than in children with only one Greenlandic born parent. A follow-up study after one year in Sisimiut revealed unchanged or aggravated middle ear disease in 56.8% of 82 children with middle ear pathology at the primary survey. Thus, OM persists as a major health problem among Greenlandic children, although the general socio-economic and medical conditions have improved during the last decades. Proposals are provided for increased otologic efforts.

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.

Immunohistochemical and quantitative changes in salivary EGF, amylase and haptocorrin following radiotherapy for oral cancer

Epidermal growth factor (EGF), amylase and haptocorrin are molecules produced in the salivary glands. The aim of the present study was to determine immunohistochemical and quantitative alterations in EGF as compared with haptocorrin and amylase following radiotherapy for oral cancer. Changes in the salivary secretion of EGF are of interest because of the importance of EGF in mucosal regeneration. Immunohistochemical studies on normal tissue from parotid and submandibular glands have demonstrated EGF in the serous acini with a tendency to single cell expression in the parotid gland. Amylase has been found in the serous acini of both the submandibular and parotid glands. Haptocorrin was localized in the duct system of both glands. In the submandibular glands with radiotherapy induced sialoadenitis only very few acini with weak or no staining for EGF and amylase were demonstrated, while no changes were observed in the staining for haptocorrin. Analysis on stimulated whole saliva samples collected from 20 healthy individuals and from 20 patients prior to, and 1, 2 and 3 weeks following radiotherapy showed significant reduction in salivary contents of EGF and amylase after treatment as expressed per g protein (p < 0.0002). The salivary content of haptocorrin increased significantly after treatment (p < 0.002). These alterations may be explained by the different cellular sites of the molecules studied, the serous acini being more sensitive to ionising radiation than the duct system. The concentration of EGF in saliva before treatment was significantly higher in patients than in the control group (p < 0.02), which may indicate that the tumors induce increased secretion of salivary EGF, or alternatively that the oral tumors contribute with EGF to the saliva. In conclusion we have demonstrated a reduction in the mitogenic peptide EGF both immunohistochemically and quantitatively following irradiation for oral cancer, results which may contribute to the understanding of the clinical signs of mucositis.

A sensitive enzyme-linked immunosorbent assay used for quantitation of epidermal growth factor receptor protein in head and neck carcinomas: evaluation, interpretations and limitations

The EGF receptor is a transmembrane glycoprotein exerting mitogenic effects on epithelial cells. The purpose of the present study was to develop a sensitive enzyme-linked immunosorbent assay (ELISA) for determination of the epidermal growth factor receptor (EGFR) protein to examine whether the receptor was overexpressed in head and neck squamous cell carcinomas compared with the normal counterpart, and to establish whether clinicopathological correlations were present by investigating a broad spectrum of parameters (tumour size, clinical stage, positive lymph nodes, tumour site, histological grade, keratinisation, preoperative irradiation and clinical outcome). The assay employs two commercially available monoclonal antibodies, both detecting protein epitopes. The material comprises 60 head and neck carcinomas, corresponding normal tissue and normal oral mucosa from healthy individuals. The study demonstrates significantly higher receptor levels in tumours compared with normal tissue (P < 0.002) and a range in tumours and normal tissues of 0.4-10.5 and 0.1-4.3 nmol g-1 membrane protein respectively. Quantitation of receptors in normal mucosa emphasises the importance of using the patients' corresponding normal tissue, because using the patients' mucosa resulted in 83% overexpression, while using normal mucosa from healthy individuals only demonstrated overexpression in 50% of cases. No significant clinicopathological correlations could be established, although the mean values for EGFR increased with tumour size and advanced clinical stage. Furthermore, the prognostic value concerning disease-free survival, recurrence and the time interval for recurrence were investigated but no significance could be demonstrated. In conclusion, the investigation supports the theory of overexpression of EGFR protein as a common motif for malignant epithelial tumours, but limitations in interpretations are demonstrated and discussed further.

The suspensory ligament of the endolymphatic duct in the rat. An ultrastructural study

Following optimized fixation and specimen handling, the endolymphatic duct was investigated by transmission and scanning electron microscopy. Tubular microfibrils, 10-12 nm thick and of indefinite length, occupied the subepithelial compartment abundantly and seemed to insert into the basal lamina of the epithelial cells of the duct and to merge with the bony wall of vestibular aqueduct thus forming a suspensory ligament of the endolymphatic duct. This ligament is suggested to protect the endolymphtaic duct from collapsing and to play a role in the mechanical protection of the vestibular apparatus from sudden increases in intracranial pressure. The capillaries and the aqueductal vein were located in intimate relationship to the epithelial cells. Both types of vessels were provided with fenestrations of the endothelial cells, supporting the proposal that the endolymphatic duct may be involved in the resorption of endolymph.

[Cancer in the middle ear and the auditory canal]

Thirty-seven patients with malignant tumours in the ear treated at Rigshospitalet, Copenhagen in the period 1.6.1983-1.6.1993 were retrospectively reviewed. There were 20 males and 17 females. The average age was 67 years. Twenty-four patients had tumours involving the middle ear and 13 patients had tumours located only in the external auditory canal. Eighty-four percent had squamous cell carcinoma. In 61% of the patients with squamous cell carcinoma, chronic infection of the ear preceded the malignant process. Overall control of disease for the 37 patients was 49%. The total actuarial crude survival was 33%. For the nine patients who had squamous cell carcinoma located only in the external auditory canal, the control of disease was 89%. Twenty-two patients had squamous cell carcinoma involving the middle ear. Most of these patients underwent radical mastoidectomy and step-wise removal of gross tumour followed by radiotherapy. Six had radiotherapy alone. The control of disease in this group was 32%. It is concluded that tumours involving only the external auditory canal have a good prognosis. If the tumour involves the middle ear, the prognosis falls dramatically.

Fine structure of the endolymphatic duct in the rat. A scanning and transmission electron microscopy study

To investigate the surface morphology of the endolymphatic duct epithelium, 8 rats were vascularly perfused with glutaraldehyde in a buffered and oxygenated blood substitute. Optimal preservation of the epithelium for scanning electron microscopy was attained by coating of the specimens with OsO4 and thiocarbohydrazide followed by a continuous dehydration procedure. Three types of cells were identified with the scanning electron microscope: A polygonal and oblong epithelial cell was observed in the largest number throughout the duct, whereas in the juxta-saccular half of the duct two additional types of epithelial cells were observed. The scanning electron microscopical observations are compared and discussed with reference to transmission electron microscopical observations of the endolymphatic duct.

Surface morphology of the endolymphatic duct in the rat. A scanning electron microscopy study

Following intracardiac vascular perfusion fixation of 8 rats with glutaraldehyde in a buffered and oxygenated blood substitute, the vestibular aqueduct and endolymphatic duct were opened by microsurgery of the resulting 16 temporal bones. Optimum preservation of the epithelium for scanning electron microscopy was attained by coating of the specimens with osmium tetroxide and thiocarbohydrazide followed by a continuous dehydration procedure. This technique permitted, for the first time, an investigation of the surface morphology of the epithelial cells in the endolymphatic duct. Three types of cells were identified with the scanning electron microscope. A polygonal and oblong epithelial cell was observed in the largest number throughout the duct, and in the juxtasaccular half of the duct, two additional types of epithelial cells were observed. The scanning electron microscopic observations are compared and discussed with reference to previous transmission electron microscopic studies of the endolymphatic duct.

[Bone-anchored auricular prosthesis]

During the period February 1989-September 1991, 15 patients with absent or defective pinna were treated with a bone-anchored auricular prosthesis at the ENT-department, Rigshospitalet, Copenhagen. These patients were followed up from the hospital records and by means of a questionnaire. Altogether 40 titanium implants have been inserted, of which one implant was found not to be integrated at the time of the second-stage surgery. Five patients underwent additional surgery, one patient because of non-integration of a screw, and four patients on account of soft-tissue reactions. From the questionnaire replies it appears that all patients found the cosmetic result and the technique concerning mounting of the prosthesis very satisfactory. Nearly half the patients found that the care of the skin around the abutments caused considerable problems. Three patients had experienced unintended losses of the prosthesis. In conclusion, treatment with a bone anchored auricular prosthesis has considerable advantages compared to treatment with a prosthesis attached by adhesive. Furthermore the use of a bone-anchored prosthesis should be considered a viable alternative to surgical reconstruction because of the outstanding aesthetic result and because the surgical procedure puts less strain on the patient. The disadvantage of the method is the lifelong daily care of the skin and the dependence on the health services.