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Failure in the structural maintenance of the hair cell stereocilia bundle and ribbon synapse causes hearing loss. Here, we have studied how ER stress elicits hair cell pathology, using mouse models with inactivation of Manf (mesencephalic astrocytederived neurotrophic factor), encoding an ER-homeostasispromoting protein. From hearing onset, Manf deficiency caused disarray of the outer hair cell stereocilia bundle and reduced cochlear sound amplification capability throughout the tonotopic axis. In high-frequency outer hair cells, the pathology ended in molecular changes in the stereocilia taper region and in strong stereocilia fusion. In high-frequency inner hair cells, Manf deficiency degraded ribbon synapses. The altered phenotype strongly depended on the mouse genetic background. Altogether, the failure in the ER homeostasis maintenance induced early-onset stereociliopathy and synaptopathy and accelerated the effect of genetic causes driving age-related hearing loss. Correspondingly, MANF mutation in a human patient induced severe sensorineural hearing loss from a young age onward. Thus, we present MANF as a novel protein and ER stress as a mechanism that regulate auditory hair cell maintenance in both mice and humans.

Vertaisarvioitu. Susacin oireyhtymä on harvinainen endoteelin tulehdussairaus, joka ilmenee erityisesti kolmessa sijainnissa: verkkokalvon, sisäkorvan ja aivojen pikkuvaltimoissa. Sen ajatellaan olevan autoimmuunisairaus, jossa epätarkoituksenmukainen tulehdusreaktio kohdistuu pienten valtimoiden endoteeliin, aiheuttaa verenkiertohäiriöitä ja eksudaattia valtimon ympärille sekä siten kohde-elimen toimintahäiriöitä (näkökenttäpuutokset ja valonvälähdykset, kuulon heikkeneminen). Diagnoosi perustuu keskeisesti verkkokalvon kuvantamislöydöksiin. Lisätukea diagnoosille voidaan saada aivojen magneettikuvauksesta ja mahdollisen sisäkorvaperäisen kuulon heikkenemisen osoittamisesta. Näyttöön perustuvia hoitosuosituksia ei ole, mutta immuunijärjestelmää hillitsevällä ja antitromboottisella lääkityksellä voidaan vaikuttaa taudinkulkuun. Hoitoa tulisi tehostaa nopeasti, mikäli runsaita aivomuutoksia ilmenee.

Sisäkorvaistutehoito sopii sekä synnynnäisen vaikea-asteisen kuulovian että etenevän kuulovian hoidoksi. Istutteella voidaan saavuttaa hyvä puheentunnistuskyky vaikea-asteisessa kuulonalenemassa. Hoito on osoitettu kustannusvaikuttavaksi kaikissa ikäryhmissä. Nuorimmat potilaat ovat olleet 8–10 kuukauden ja vanhimmat yli 80 vuoden ikäisiä. Vanhusväestössä on paljon vaikea-asteisesta kuuloviasta kärsiviä potilaita, jotka hyötyisivät istutehoidosta. Heitä tulisi ohjata nykyistä aktiivisemmin leikkausarvioon.

Väestön ikääntyessä kuulonalenemien esiintyvyys ja tarve vaikuttavaan kuulonkuntoutukseen kasvavat. Hyvän yleiskäsityksen kuulosta antavat äänieriön hiljaisuudessa tehtävät perustutkimukset, äänesaudiometria ja puheaudiometria. Ne eivät kuitenkaan välttämättä kuvasta kuulonaleneman aiheuttamaa haittaa hälyisissä tilanteissa. Uuden suomenkielisen hälylausetestin avulla voidaan tutkia aiempaa paremmin aikuisten kuntoutuspotilaiden kuulonvaraista selviämistä arjessa. Suomenkielisen lasten hälypuhetestin validointi on meneillään.

Acute otitis media is a common infection in children. Most acute otitis media episodes can be treated at an outpatient setting with antimicrobials, or only expectant observation. Hospital treatment with parenteral medication, and myringotomy or tympanostomy, may be needed to treat those with severe, prolonged symptoms, or with complications. The most common intratemporal complication of acute otitis media is acute mastoiditis. If a child with acute mastoiditis does not respond to this treatment, or if complications develop, further examinations and other surgical procedures, including mastoidectomy, are considered. Since the treatment of complicated acute otitis media and complicated acute mastoiditis differs, it is important to differentiate these two conditions. This article focuses on the differential diagnostics of acute otitis media and acute mastoiditis in children.

English summary

Background In rat, deafferentation of one labyrinth (unilateral labyrinthectomy) results in a characteristic syndrome of ocular and motor postural disorders (e.g., barrel rotation, circling behavior, and spontaneous nystagmus). Behavioral recovery (e.g., diminished symptoms), encompassing 1 week after unilateral labyrinthectomy, has been termed vestibular compensation. Evidence suggesting that the histamine H3 receptor plays a key role in vestibular compensation comes from studies indicating that betahistine, a histamine-like drug that acts as both a partial histamine H1 receptor agonist and an H3 receptor antagonist, can accelerate the process of vestibular compensation. Results Expression levels for histamine H3 receptor (total) as well as three isoforms which display variable lengths of the third intracellular loop of the receptor were analyzed using in situ hybridization on brain sections containing the rat medial vestibular nucleus after unilateral labyrinthectomy. We compared these expression levels to H3 receptor binding densities. Total H3 receptor mRNA levels (detected by oligo probe H3X) as well as mRNA levels of the three receptor isoforms studied (detected by oligo probes H3A, H3B, and H3C) showed a pattern of increase, which was bilaterally significant at 24 h post-lesion for both H3X and H3C, followed by significant bilateral decreases in medial vestibular nuclei occurring 48 h (H3X and H3B) and 1 week post-lesion (H3A, H3B, and H3C). Expression levels of H3B was an exception to the forementioned pattern with significant decreases already detected at 24 h post-lesion. Coinciding with the decreasing trends in H3 receptor mRNA levels was an observed increase in H3 receptor binding densities occurring in the ipsilateral medial vestibular nuclei 48 h post-lesion. Conclusion Progressive recovery of the resting discharge of the deafferentated medial vestibular nuclei neurons results in functional restoration of the static postural and occulomotor deficits, usually occurring within a time frame of 48 hours in rats. Our data suggests that the H3 receptor may be an essential part of pre-synaptic mechanisms required for reestablishing resting activities 48 h after unilateral labyrinthectomy.

Tinnitus, or the perception of sounds without an external source, affects up to 15% of the adult population worldwide. It relates to a number of psychological and psychiatric disorders such as psychological distress, insomnia and depression, and develops on a broad range of physical insults. To date, it is nearly impossible to obtain quantitative data on this symptom and thus complaints are often labelled as ‘only’ imaginary. Nevertheless, the sheer number of affected individuals makes it clear that tinnitus is everything but an orphan symptom. Variations in the clinical presentation may arise from the specific physical insult, the quality of first diagnosis and immediate medical aid as well as genetic predisposition. Thus, regional differences have to be considered when approaching tinnitus patients. The aim of this thesis was to study patient populations managed for tinnitus at the Department of Otorhinolaryngology - Head and Neck Surgery, Helsinki University Hospital (Helsinki, Finland). In the first study, we were able to show that music exposure even at low volume can pose a noise trauma and tinnitus occurs long before tone-audiometric hearing disabilities become evident. The alarming finding of the second study was its confirmation of pediatric tinnitus as a largely ignored symptom and that tinnitus in the childhood is under-diagnosed and this may have severe consequences for development of the individual. The third study could demonstrate that pupillometry can be considered as a viable option for studying autonomic activation in tinnitus subjects and emphasized the close link between tinnitus and depression. From our fourth study, a systematic literature review, we cannot clearly conclude if tinnitus and suicide are interrelated entities. The results of the last study indicate that tinnitus patients describe their own perceived tinnitus sound as well as external given sounds very divergent and therefore subjective tinnitus descriptions should be interpreted with great caution. Taken together, an early recognition of tinnitus symptoms may increase not only the overall quality of life of the affected patients, more importantly, it may decrease the risk of psychological and psychiatric co-morbidities and suicidal behavior. A major limitation still is that tinnitus lacks both, clear-cut biomarkers that are specific enough to be allocated solely to the symptom and methods that are sensitive enough to detect them.

Prosthetic infection represents a major problem in the outcome of patients after implantation of a foreign body. The presence of biomaterial in the body provides a substratum to host either tissue-cell integration or bacterial colonization. In obliteration of an infected bone, artificial bone substitutes and rigid fixation materials are usually necessary to fill bone cavity and to restore the properties of the bone respectively. This study attempted to discover the effect of bioactive glass bone substitute granules (BAG) S53P4 on bacterial and human-cell adhesion on other implant used simultaneously (I, II). During development of new infection-resistant biomaterials, adherence and colonization of either bacterial cells or tissue cells on biomaterials must be evaluated in parallel. A methodology allowing study of the simultaneous growth of bacteria and tissue cells on the same biomaterial surface was developed. This will allow discovery of the effect of various bacterial concentrations on host-cell viability and integration with an implant surface, and their relation to increasing reactive oxygen species (ROS) levels and cell apoptosis (III). Finally, considering our first results and that microorganisms frequently infect an implant surface during surgery and start to compete for the surface before tissue integration, it was hypothesized that incubation of implants with host cells before implantation may be one way to reduce the bacterial living space available and would prevent bacterial adhesion and consequently the infection of biomaterials (IV). Bacterial and human osteoblast-like osteosarcoma cells (SaOS-2) or primary osteoblast (hOB) cells were incubated for 4.5 hours, 2 days, or 4 days at 37°C. As substratum, titanium (Ti), polytetrafluoroethylene (PTFE), polydimethyl-siloxane (PDMS), or bioactive glass plates (IV) were used. The study was done separately (I, II), in competition with SaOS-2 or hOB (III), or in competition with SaOS-2 after 24-hour pre-incubation with SaOS-2 (IV). The effect of BAG S53P4 on bacteria (I) and cell (II) adhesion was studied in either a normal atmosphere or in hypoxia-simulating atmospheric conditions of the middle ear, mastoid cavity, or sinuses. Human osteoblast-like SaOS-2 cells or primary osteoblast (hOB) cells (III) (both, 1x105cells/mL), and collection strains of Staphylococcus aureus and Staphylococcus epidermidis (I) [108 colony forming units (CFU) (I) or (serial 1:10 dilutions of 108 CFU (III, IV)] were employed. The bacteria and cell proliferation, cytotoxicity (III, IV), and production of reactive oxygen species (ROS) (III) were evaluated by colorimetric (MTT, LDH, and crystal violet) (III, IV) as well as by fluorometric methods (fluorescent microscopy and flow cytometry) (III). Bacterial cell viability was studied by use of a drop-plate method after sonication. Effects of BAG S53P4 on cell adhesion were linked intimately with modifications of cellular attachment organs (vinculin containing focal adhesions), rearrangement of the actin cytoskeleton, and cellular spreading. The presence of bioglass under normoxic and hypoxic conditions prevented bacterial and biofilm adhesion for most of the materials and promoted integration of SaOS-2 cells with various biomaterial surfaces, especially under hypoxic conditions, in which S53P4 granules cause increased pH (I, II). In the competitive study, the presence of bacteria resulted in reduced adherence of human cells to the surface of the biomaterials, increased production of ROS, and increased apoptosis. The presence of either type of human cell was associated with a reduction in bacteria compared with that for the materials incubated with S. aureus only (III). Pretreatment with human cells was also associated with a reduction in bacterial colonization of the biomaterial compared with that of the non-pretreated materials, but the presence of bacteria produced a decrease in viable human cells for all materials (IV). In conclusion, the presence of S53P4 granules may both protect implants from bacterial colonization and promote their osteointegration. In the presence of bacteria and cells, colonization of the surface by one reduces colonization by the other. The bacteria produce cellular oxidative stress in human cells, which may be related to the cellular death. The preoperative incubation of prostheses with host cells could be a new way to prevent infection of biomaterials and lessen the risk for bacterial antibiotic resistance.

Acute otitis media (AOM) is an infection that is particularly common in children. The bacterial etiology of AOM, in both children and adults, affects its clinical picture. While in some cases the infection can simply be carefully monitored without treatment, antimicrobials are often prescribed. Caution is required, however, when prescribing antimicrobials as their excessive use has led to antimicrobial resistance; this resistance has been seen among some of the causative pathogens for these infections. Before the development of antimicrobial treatment, complications due to middle ear infections were common, potentially causing severe symptoms or even death. Some middle ear infections spread into surrounding structures, leading to intratemporal or extratemporal (extracranial or intracranial) complications. This thesis focuses on complicated otitis media and the causative factors of its complications. In the first two studies, we evaluated the medical records of all (n=100) children (0-16 years old) hospitalized at the Department of Otorhinolaryngology in the Helsinki University Hospital from 2003 to 2012 for acute mastoiditis (AM) or AOM, as well as the infection s bacteriology in relation to the patient s clinical findings and treatment. Using this information, we analyzed the differences in the etiologies and clinical pictures of those children hospitalized due to AOM compared to AM. In our third study, we examined the medical records of all (n=166) patients hospitalized at our institution from 1970 to 2012 due to intracranial abscesses (IA), including those of otogenic background (oIA). In the fourth study, we evaluated the bacteriology in relation to the patients clinical findings and treatment in all (n=160) adult patients treated at our institution from 2003 to 2012 for AOM or acute mastoid infection. In adults, acute mastoid infection was subclassified into AM, latent mastoiditis (LM), and AM following chronic middle ear infection (AMc). The clinical picture of AM in children differed according to the causative pathogen. Streptococcus pneumoniae (Pnc), especially its resistant strains, caused severe symptoms and often led to mastoidectomies. Pseudomonas aeruginosa (Ps) typically affected older children with prior tympanostomy tubes and generally caused milder symptoms. Furthermore, the bacteriological etiology of hospitalized AOM and AM patients was different compared to outpatient AOM. Two of the typical AOM pathogens, Haemophilus influenzae (Hi) and Moraxella catarrhalis (Mc), were uncommon among the hospitalized patients. Pnc, especially its resistant strains, was less common in children hospitalized for AOM compared to AM, and less common in adults than children. Streptococcus pyogenes (StrA) and Ps were both linked to otorrhea and were found only in older children. Over our 42 year study period, oIAs became less common and typically developed following chronic middle ear infections, often in connection with cholesteatoma. In adults, the bacteriological etiology and clinical picture of AMc differed from AOM as well as the other acute mastoid infection types (AM, LM). AOM and AM led to less surgical procedures than the more prolonged forms of acute mastoid infection (LM, AMc). In children, the hospitalized cases of AOM and AM differed from outpatient AOM. In adults, severe AOM, AM, and LM seem to compose a continuum that may lead to chronic otitis media and its acute complications, including oIAs. Otogenic IAs are quite rare, however, and became less common over our study period. Äkillinen välikorvatulehdus on yksi lasten tavallisimmista taudeista; aikuisilla se on lapsia harvinaisempi. Vaikka pelkkä seuranta voi riittää äkillisen välikorvatulehduksen hoidoksi, usein hoitona käytetään antibioottia. Välikorvatulehdus voi levitä välikorvaa ympäröiviin rakenteisiin aiheuttaen vakaviakin komplikaatioita (esim. kartiolisäketulehdus, aivopaise). Ennen antibioottien kehittämistä välikorvatulehduksen komplikaatioita esiintyi nykyistä enemmän. Turhaa antibioottien käyttöä on vältettävä, mutta komplisoitunutta tautia sairastavat potilaat on tunnistettava varhain ja hoidettava tehokkaasti. Tässä tutkimuksessa selvitettiin komplisoituneen välikorvatulehduksen taustatekijöitä. Äkillisen kartiolisäketulehduksen tai välikorvatulehduksen vuoksi HUS:n Korvaklinikalle sairaalahoitoon vuosina 2003 2012 joutuneiden potilaiden (100 lasta, 160 aikuista) sairauskertomustiedot käytiin läpi. Bakteereiden suhdetta taudinkuvaan ja hoitoon arvioitiin, ja potilasryhmien tietoja vertailtiin keskenään. Kaikkien aivopaiseen vuoksi sairaalahoitoon HUS:n Neurokirurgian klinikalle vuosina 1970 2012 joutuneiden potilaiden (166) sairauskertomustiedot käytiin läpi. Aineistoon sisältyivät myös korvaperäiset aivopaiseet. Streptococcus pneumoniae on tavallinen välikorvatulehduksen taudinaiheuttaja, myös tässä tutkimuksessa. Erityisesti kartiolisäketulehdusta sairastavilla lapsipotilailla esiintyi muita lapsia ja aikuisia enemmän tavallisille korvatulehduksen hoidossa käytettäville antibiooteille vastustuskykyisiä Streptococcus pneumoniae -kantoja. Nämä johtivat muita taudinaiheuttajia useammin kartiolisäkkeen puhdistusleikkauksiin. Kaksi tavallisimmista äkillisen välikorvatulehduksen taudinaiheuttajista, Haemophilus influenzae ja Moraxella catarrhalis, olivat sen sijaan harvinaisia komplisoitunutta välikorvatulehdusta sairastavilla potilailla. Aikuisilla pitkäkestoisten välikorvatulehdusten äkillisiin komplikaatioihin liittyi enemmän leikkaushoidon tarvetta kuin äkillisten välikorvatulehdusten komplikaatioihin. Korvaperäiset aivopaiseet harvinaistuivat ajan kuluessa, ja ne liittyivät yleensä pitkäkestoiseen välikorvatulehdukseen ja helmiäiskasvamaan. Avohoidossa hoidettava välikorvatulehdus eroaa sairaalahoitoon johtaneesta välikorvatulehduksesta ja kartiolisäketulehduksesta. Välikorvatulehduksen komplikaatiot voivat johtaa pitkäkestoiseen välikorvatulehdukseen ja sen akuutteihin komplikaatioihin, myös aivopaiseisiin. Korvaperäiset aivopaiseet olivat tutkimusaineistossa kuitenkin harvinaisia, ja niiden määrä vähentyi tutkimusjakson kuluessa.

Välikorvaleikkauksiin usein liittyvän välikorvan ja kuuloluuketjun kirurgisen rekonstruktion tavoitteena on luoda olosuhteet, jotka mahdollistavat hyvän kuulon sekä välikorvan säilymisen tulehduksettomana ja ilmapitoisena. Välikorvan rekonstruktiossa on käytetty implanttimateriaaleina perinteisesti potilaan omia kudoksia sekä tarvittaessa erilaisia hajoamattomia biomateriaaleja, mm. titaania ja silikonia. Ongelmana biomateriaalien käytössä voi olla bakteerien adherenssi eli tarttuminen vieraan materiaalin pintaan, mikä saattaa johtaa biofilmin muodostumiseen. Tämä voi aiheuttaa kroonisen, huonosti antibiootteihin reagoivan infektion kudoksessa, mikä usein käytännössä johtaa uusintaleikkaukseen ja implantin poistoon. Maitohappo- ja glykolihappopohjaiset biologisesti hajoavat polymeerit ovat olleet kliinisessä käytössä jo vuosikymmeniä. Niitä on käytetty erityisesti tukimateriaaleina mm. ortopediassa sekä kasvo- ja leukakirurgiassa. Niitä ei ole toistaiseksi käytetty välikorvakirurgiassa. Korvan kuvantamiseen käytetään ensisijaisesti tietokonetomografiaa (TT). TT-tutkimuksen ongelmana on potilaan altistuminen suhteellisen korkealle sädeannokselle, joka kasvaa kumulatiivisesti, jos kuvaus joudutaan toistamaan. Väitöskirjatyö selvittää uuden, aiemmin kliinisessä työssä rutiinisti lähinnä hampaiston ja kasvojen alueen kuvantamiseen käytetyn rajoitetun kartiokeila-TT:n soveltuvuutta korvan alueen kuvantamiseen. Väitöskirjan kahdessa ensimmäisessä osatyössä tutkittiin ja verrattiin kahden kroonisia ja postoperatiivisia korvainfektioita aiheuttavan bakteerin, Staphylococcus aureuksen ja Pseudomonas aeruginosan, in vitro adherenssia titaanin, silikonin ja kahden eri biohajoavan polymeerin (PLGA) pintaan. Lisäksi tutkittiin materiaalien albumiinipinnoituksen vaikutusta adherenssiin. Kolmannessa osatyössä tutkittiin eläinmallissa PLGA:n biokompatibiliteettia eli kudosyhteensopivuutta kokeellisessa välikorvakirurgiassa. Chinchillojen välikorviin istutettiin PLGA-materiaalia, eläimiä seurattiin, ja ne lopetettiin 6 kk:n kuluttua operaatiosta. Biokompatibiliteetin arviointi perustui kliinisiin havaintoihin sekä kudosnäytteisiin. Neljännessä osatyössä tutkittiin kartiokeila-TT:n soveltuvuutta korvan alueen kuvantamiseen vertaamalla sen tarkkuutta perinteisen spiraali-TT:n tarkkuuteen. Molemmilla laitteilla kuvattiin ohimo- eli temporaaliluita korvan alueen kliinisesti ja kirurgisesti tärkeiden rakenteiden kuvantumisen tarkkuuden arvioimiseksi. Viidennessä osatyössä arvioitiin myös operoitujen temporaaliluiden kuvantumista kartiokeila-TT:ssa. Bakteeritutkimuksissa PLGA-materiaalin pintaan tarttui keskimäärin korkeintaan saman verran tai vähemmän bakteereita kuin silikonin tai titaanin. Albumiinipinnoitus vähensi bakteeriadherenssia merkitsevästi kaikilla materiaaleilla. Eläinkokeiden perusteella PLGA todettiin hyvin siedetyksi välikorvassa. Korvakäytävissä tai välikorvissa ei todettu infektioita, tärykalvon perforaatioita tai materiaalin esiin työntymistä. Kudosnäytteissä näkyi lievää tulehdusreaktiota ja fibroosia implantin ympärillä. Temporaaliluutöissä rajoitettu kartiokeila-TT todettiin vähintään yhtä tarkaksi menetelmäksi kuin spiraali-TT välikorvan ja sisäkorvan rakenteiden kuvantamisessa, ja sen aiheuttama kertasäderasitus todettiin spiraali-TT:n vastaavaa huomattavasti vähäisemmäksi. Kartiokeila-TT soveltui hyvin välikorvaimplanttien ja postoperatiivisen korvan kuvantamiseen. Tulokset osoittavat, että PLGA on välikorvakirurgiaan soveltuva, turvallinen ja kudosyhteensopiva biomateriaali. Biomateriaalien pinnoittaminen albumiinilla vähentää merkittävästi bakteeriadherenssia niihin, mikä puoltaa pinnoituksen soveltamista implanttikirurgiassa. Kartiokeila-TT soveltuu korvan alueen kuvantamiseen. Sen tarkkuus kliinisesti tärkeiden rakenteiden osoittamisessa on vähintään yhtä hyvä ja sen potilaalle aiheuttama sädeannos pienempi kuin nykyisen korva-spiraali-TT:n. Tämä tekee menetelmästä spiraali-TT:aa potilasturvallisemman vaihtoehdon erityisesti, jos potilaan tilanne vaatii seurantaa ja useampia kuvauksia, ja jos halutaan kuvata rajoitettuja alueita uni- tai bilateraalisesti. Polylactic- and polyglycolic acid-based degradable biomaterials are in wide clinical use especially in orthopedic and craniomaxillofacial surgery, and in general they have proved to be safe and well-tolerated implant materials. Thus far, they have not been used in reconstructive human middle ear surgery. Common problems related to implant surgery are microbial biofilm formation on medical implants in vivo and subsequent infection. A postoperative implant infection often leads to re-operation and implant removal. The present thesis clarifies the surface properties of polylactic-glycolic acid (PLGA) in relation to bacterial adherence—the first step in biofilm formation—and the biocompatibility of the material in the middle ear. Furthermore, a new application has been studied for imaging of the middle ear with a lower radiation dose than with the present computed tomography (CT) of the ear. This method, cone-beam computed tomography (CBCT), has been used particularly in dental and maxillofacial imaging, where it allows accurate, 3D imaging of a defined area. The first two studies of this thesis tested in vitro adherence of two common pathogens of a chronically or postoperatively infected ear, Staphylococcus aureus and Pseudomonas aeruginosa, onto the surfaces of PLGA and of two common implant materials used in ear surgery: silicone and titanium. In addition, the effect of albumin coating on adherence to these materials was tested and compared. Next, applicability of the PLGA material to reconstructive middle ear surgery was explored by study of its biocompatibility in the middle ear in an animal model in which chinchillas were operated on, followed-up, and killed at 6 months postoperatively. Biocompatibilities of the implanted materials were evaluated according to clinical and histological findings. Suitability of the CBCT for imaging of the ear was tested by imaging human cadaver temporal bones and comparing scaled accuracies of the images created by CBCT with those constructed with traditional multislice helical CT. There proved to be no more bacterial adherence in vitro to the PLGA materials tested than to silicone and titanium. Albumin coating significantly reduced bacterial adherence to every material tested. The biocompatibility of PLGA in the middle ear of the chinchilla was very good. In histological samples, only a mild inflammatory reaction was evident around the degrading PLGA plates. Clinically, no infections or extrusion of the implanted material occurred. Limited CBCT was found to be at least as accurate as conventional multislice helical CT in showing the clinically and surgically important landmarks of the middle and inner ear. The effective radiation dose was essentially lower with the CBCT than with the helical CT used in this study. Visualization of the middle ear structures and implants of operated temporal bones was clear and of diagnostic value. Based on the results of the thesis, it can be concluded that PLGA is a safe and well-tolerated implant material in the middle ear area, and there is no greater in vitro adherence of S. aureus and P. aeruginosa to PLGA surfaces than to titanium and silicone. In addition, coating of these materials with albumin means that adherence of the bacteria to their surfaces can be substantially reduced, suggesting that this method may be useful in implant surgery as a preventive maneuver against postoperative infections. Furthermore, CBCT seems to be a promising new method for imaging the structures of the temporal bone. The diagnostic accuracy of CBCT corresponds to that of helical CT, while the radiation dose to patient per investigation remains lower with CBCT. Focused imaging with the lesser radiation exposure expands the possibilities for imaging the ear, especially when follow-up and limited uni- or bilateral examination is needed.