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The SARS-CoV-2 pandemic has led to profound limitations in patient care and student teaching at the University Hospitals of Otorhinolaryngology (ORL). In contrast, the impact on research has been variable. To classify the pandemic-related effect on research, the development of the number of scientific publications of the German ORL university hospitals before and during the pandemic was analyzed.The publication performance between 2015 and 2020 of the 39 current chairmen was surveyed using a literature search (Pubmed). All entries relating to the chairmen of the university hospital as first, last or co-author were included. The absolute and relative development of each author's publication performance was determined and evaluated using nonparametric statistical methods.A total of 2420 publications could be documented. From 2015 to 2019, an average of 368 publications were published per year. In 2020, this number increased by 57.9 % to 581 publications. While the number of monthly publications remained constant between 2015 and 2019, a significant increase was seen from May 2020 up to a maximum of 74 publications in September 2020. In 2020, 34 articles (5.9 %) had a thematic relation to the SARS-CoV-2 pandemic, with 7 of these papers (20.6 %) resulting from cross-site publications.In 2020, the number of scientific publications was raised to more than 1.5 times the usual annual publications. This increase was clearly related in time to the reduction of elective patient care during the SARS-CoV-2 pandemic starting in mid-March 2020. Probably, free time capacities enabled this increased publication output. Our results confirm the great scientific potential of the ORL university hospitals, which has been successfully implemented despite the pandemic.Die SARS-CoV-2-Pandemie hat an den Universitätskliniken für Hals-Nasen-Ohrenheilkunde (HNO) zu tiefgreifenden Einschränkungen im Bereich der Krankenversorgung und der studentischen Lehre geführt. Die Auswirkungen auf den Bereich Forschung sind dagegen uneinheitlich. Zur Einordnung der pandemiebedingten Effekte auf die Forschung wurde die Entwicklung der Anzahl der wissenschaftlichen Publikationen der HNO-Universitätskliniken in Deutschland vor und während der Pandemie analysiert.Es wurde die Publikationsleistung aus den Jahren 2015–2020 der derzeitigen 39 Klinikdirektoren mithilfe einer Literaturrecherche (PubMed) erhoben. Eingeschlossen wurden alle Nennungen der Klinikdirektoren als Erst-, Letzt- oder Co-Autor einer Arbeit. Es wurde die absolute und relative Entwicklung der Publikationsleistung jedes Autors ermittelt und statistisch ausgewertet.Die Literaturrecherche ergab 2420 Publikationen. Zwischen 2015 und 2019 wurden pro Jahr durchschnittlich 368 Publikationen von allen Autoren veröffentlicht. 2020 stieg diese Zahl um 57,9 % auf 581 Publikationen an. Während zwischen 2015 und 2019 die Anzahl der monatlichen Publikationen konstant blieb, zeigte sich ab Mai 2020 ein deutlicher Anstieg bis zu einem Maximum von 74 Veröffentlichungen im September 2020. 34 Arbeiten (5,9 %) aus dem Jahr 2020 wiesen einen thematischen Bezug zur SARS-CoV-2-Pandemie auf, wobei 7 dieser Arbeiten (20,6 %) durch standortübergreifende Veröffentlichungen entstanden sind.Im Jahr 2020 konnte die Zahl der wissenschaftlichen Publikationen auf mehr als das 1,5-fache der Veröffentlichungen der Vorjahre gesteigert werden. Diese Steigerung stand in einem deutlichen zeitlichen Zusammenhang zur Reduktion der elektiven Krankenversorgung während der SARS-CoV-2-Pandemie ab Mitte März 2020. Wahrscheinlich haben freie zeitliche Kapazitäten diese gesteigerte Publikationsleistung ermöglicht. Unsere Ergebnisse belegen das große wissenschaftliche Potenzial der universitären HNO-Kliniken, das trotz der Pandemie erfolgreich umgesetzt werden konnte.

The treatment of patients with severe hearing loss or deafness with a cochlear implant (CI) represents a standard in Germany today. However, there is hardly any data on the current number of clinical CI centers (CI clinics) and their geographical distribution. The patient self-help organization, German Cochlear Implant Society (DCIG), and the German Society for Otorhinolaryngology, Head and Neck Surgery (DGHNO-KHC) have therefore initiated a survey to determine the regional distribution, the range of services, the consideration of existing quality standards and cooperation with patient self-help organizations of the individual clinical CI centers.For this purpose, a total number of 170 ENT departments or their directors (37 professors and 133 chief physicians), respectively, were contacted by e-mail and provided with a questionnaire. The survey took place from October 2019 to February 2020.Of the 170 departments contacted, 71 (41.8 %) took part in the survey. Of these, 70 departments (98.6 %) confirmed to perform CI surgeries. Thus, 41.8 % of all clinics contacted reported to perform CI surgeries (70 of 170 clinics), while this information was not available from 99 clinics. All 70 clinical CI centers (100 %) reported to conduct CI surgeries on adults, 60 centers (85.7 %) also on children ( 18 years). 36 departments (51.4 %) reported that the total number of CI surgeries at their facility in 2018 was more than 50. In 64 departments (91.4 %), the recommendations of the DGHNO-KHC on CI care (according to the White Paper CI care 2018) were followed. A collaboration between the department and patient self-help organization was confirmed by 67 institutions (95.7 %). The geographical distribution of the clinical CI centers showed a heterogeneous distribution pattern between the individual federal states and also within the respective federal state.The work presented here is a first assessment of the situation with regard to the regional distribution of clinical CI centers in Germany. A clustering of CI centers was noticeable in metropolitan areas, sometimes with several facilities in one city. The predominant attention to quality-related aspects, such as the consideration of the DGHNO-KHC white paper and the cooperation with patient self-help, is gratifying. The limitations of the study result from limited participation in the survey (41.8 % of the contacted clinics).Die Versorgung von Patienten mit einer hochgradigen Schwerhörigkeit oder Taubheit mit einem Cochlea-Implantat (CI) stellt heute in Deutschland einen Standard dar. Umso überraschender ist es, dass kaum Daten zur aktuellen Anzahl der CI-versorgenden Einrichtungen (CI-Kliniken) und zu deren geografischer Verteilung existieren. Der Selbsthilfeverband Deutsche Cochlea Implantat Gesellschaft (DCIG) e. V. und die Deutsche Gesellschaft für Hals-Nasen-Ohrenheilkunde, Kopf- und Halschirurgie (DGHNO-KHC) haben daher eine Umfrage zur Erfassung der regionalen Verteilung, des Leistungsspektrums, der Berücksichtigung existierender Qualitätsstandards sowie der Zusammenarbeit mit Patientenselbsthilfe-Organisationen der einzelnen CI-versorgenden Einrichtungen initiiert.Hierfür wurden insgesamt 170 Kliniken für Hals-Nasen-Ohrenheilkunde bzw. deren ärztliche Leiter (37 Lehrstuhlinhaber und 133 Chefärzte) per E-Mail kontaktiert und mittels Fragebogens befragt. Die Befragung erfolgte von Oktober 2019 bis Februar 2020.Von den 170 kontaktierten Kliniken nahmen 71 (41,8 %) an der Umfrage teil. Hiervon bestätigten 70 Kliniken (98,6 %), CI-Operationen durchzuführen. Damit gaben 41,8 % aller kontaktierten Kliniken an, CI-Operationen durchzuführen (70 von 170 Kliniken), während diese Information von 99 Kliniken nicht verfügbar war. Alle 70 CI-versorgenden Einrichtungen (100 %) gaben an, CI-Operationen an Erwachsenen, 60 Kliniken (85,7 %) ebenfalls bei Kindern ( 18 Jahre) durchzuführen. 36 Kliniken (51,4 %) berichteten, dass die Gesamtanzahl der CI-Operationen an ihrer Einrichtung im Jahr 2018 mehr als 50 betrug. In 64 Kliniken (91,4 %) werden, nach den erhobenen Daten, die Empfehlungen der DGHNO-KHC zur CI-Versorgung (gemäß Weißbuch CI-Versorgung, Stand 2018) berücksichtigt. Eine Zusammenarbeit der Klinik mit der CI-Selbsthilfe wurde von 67 Kliniken (95,7 %) angegeben. Die geografische Verteilung der CI-versorgenden Einrichtungen, die an der Umfrage teilgenommen haben, zeigte ein heterogenes Verteilungsmuster zwischen den einzelnen Bundesländern und auch innerhalb der jeweiligen Bundesländer.Die hier präsentierte Arbeit ist eine erste Standortbestimmung im Hinblick auf die regionale Verteilung der CI-versorgenden Einrichtungen in Deutschland. Auffällig ist eine Clusterbildung der CI-Kliniken in Ballungsräumen, teils mit mehreren Einrichtungen in einer Stadt. Erfreulich ist die weit überwiegende Beachtung qualitätsbezogener Aspekte, wie die Berücksichtigung des CI-Weißbuchs der DGHNO-KHC und die Zusammenarbeit mit der Patientenselbsthilfe. Limitationen der Studie ergeben sich aus der begrenzten Teilnahme an der Umfrage (41,8 % der kontaktierten Kliniken).

The audiological treatment of children with aural atresia makes high demands on physicians and acousticians. Conventional hearing systems are often not tolerated by children and therefore do not meet the needs of the early and efficient therapy of hearing disorders. Aim of the present study was the evaluation of the audiological functional gain in children with uni- and bilateral aural atresia provided with the middle ear implant Vibrant Soundbridge(®) (VSB(®)) below the age of 6 years as well as the analysis of parents' satisfaction assessed with questionnaires.The VSB(®) was implanted in 16 children, 13 with unilateral and 3 with bilateral aural atresia, with the mean age of 2;11±1;6 years. 3 months after the first fitting of the audio processor, pure-tone audiometry via free field testing with and without the hearing system was performed. Furthermore, parents completed a standardized questionnaire to evaluate their satisfaction with the VSB(®) treatment quality. The questionnaire included items on the acceptance by children, handling, listening effort, behavior, satisfaction, quality of life, aesthetics, and the length of daily use.The use of the VSB(®) resulted in a significantly improved hearing level: 20 dB on average (Z=- 3.06; p=0.002; n=12). The analysis of parents' questionnaire demonstrated high or very high satisfaction with VSB(®) in all subjects. Primarily, the length of daily use of the VSB(®) was significantly higher than that of the hearing system used before with 10.0±2.1 vs. 2.7±2.2 h per day (Z=- 3.06; p=0.002; n=14).The VSB(®) presented a good alternative for audiological treatment of uni- and bilateral aural atresia at toddler and pre-school age.

A fiberoptic endoscopic evaluation of swallowing (FEES) is well established internationally as gold standard of the instrument-based diagnostics if it is performed according to the Langmore-protocol. For the quality assurance of FEES, videotaping is recommended. However, often no videotaping is carried out due to a limited availability of portable recording systems, for instance, in the bedside diagnostics. This study aimed at the comparison of FEES quality assurance with and without videotaping by rating of the main finding in swallowing disorders, the penetration and aspiration, as defined in the penetration-aspiration scale by Rosenbek.An examination of agreement of penetration and aspiration ratings with the defined reference standard was conducted by means of 80 videotaped recordings. The ratings were carried out independently by 4 raters in 2 settings: A) "real time" and B) "frame-by-frame".As far as the interrater- and intrarater-reliability is concerned, the association between the ratings in the rating setting B were higher than those in the rating setting A. Furthermore, examination of the validity showed higher correlation in setting B than in setting A. The difference between correlations was significant in favor of setting B (videotaped FEES).The results of the present study, namely better rating reliability and validity in case of the penetration and aspiration, emphasize the importance of the videotaping of the FEES diagnostics, at least for the evaluation of penetration or aspiration.

Accumulation of secretions in hypopharynx, aditus vestibule, and trachea is often found in cases of severe dysphagia and is considered a cardinal trait of high clinical and therapeutic importance. For the graduation of the severity level of accumulated secretions, a short version of the 4-point Murray secretion scale is available, which is also integrated into the protocol of the fiberoptic endoscopic evaluation of swallowing (FEES) according to the Langmore standard. This study aimed at the validation of the German translation of this short version in order to facilitate a uniform, standardized evaluation of the accumulation of secretions in dysphagic patients in the German language area.For the examination of reliability and validity, a reference standard was defined by 2 dysphagia experts on the basis of 40 video files of the FEES examination, 10 videos for each of the severity grades. Afterwards, these videos were rated independently by 4 raters and re-rated in a new randomized order 2 weeks later.Both the intra-rater reliability (τ0,830***) and the inter-rater reliability (Kendalls W0,890***) were highly significant and can be considered good. The same is valid for the correlation of ratings with the reference standard (τ=0,969***).The German translation of the short version of the 4-point Murray secretion scale is recommendable as a reliable and valid instrument for the graduation of the cardinal trait of oropharyngeal dysphagia and also as an evidence-based instrument for standardized use in the German language area.

Preservation of residual hearing after cochlear implantation allows patients the synergetic use of electric and acoustic stimulation (EAS). The application of specific surgical and therapeutic techniques enables the reduction of inner ear trauma, which leads otherwise to complete hearing loss. Due to simultaneous electric and acoustic stimulation, speech understanding is improved especially in noise. EAS is a well-accepted therapeutic treatment for subjects with profound hearing loss in the higher frequencies and no or mild hearing loss in the low frequencies. Several Manufacturers offer individual soft electrodes specially designed for hearing preservation as well as combined electric-acoustic audio processors.

Oropharyngeal cancer of the soft palate is a therapeutic challenge. This is due to crucial importance of velopharyngeal competence for articulation and swallowing. Patient counseling must present the whole therapeutic spectrum in order to receive informed consent. Basically, in primary therapy of oropharyngeal cancer multimodal concepts have to be considered including surgical resection and radiochemotherapy. With regard to the occasional difficulties predicting the functional outcome after primary therapy the ladder of reconstructive options has to be discussed a priori. Among numerous pedicled flaps the radial forearm free flap nowadays belongs definitely in the surgical armoury, which offers almost ideal reconstructive possibilities after extensive resections. This implies some additional aspects in pre- and postoperative workup that are reviewed in this article.

The construction of facial prostheses is frequently used as a remedial treatment method in otorhinolaryngology. Modern prostheses are often attached to the face via bone anchored titanium implants and magnetic attachments. The use of specialised silicones and colouring techniques produces prostheses which realistically mimic lost facial tissues and significantly enhance patient quality of life. The article provides an overview of the possibilities of modern epithetics in the treatment of facial defects resulting from head and neck tumors.

A 35-year-old man with HIV-infection presented with a progressive swelling of the left parotid gland lasting for 3 months. Physical examination revealed a firm mass on the tail of the parotid gland. Ultrasound examination of the left parotid showed a well-circumscribed round lesion. MR imaging demonstrated a 2 cm lesion in the ventral subcutaneous part of the parotid gland. Lateral parotidectomy was performed with suspected pleomorphic adenoma. Histologic analysis revealed a granulomatous necrotising inflammatory lesion of an intra- and extraparotideal lymph node. The patient had no family history of tuberculosis. Hematologic investigations were within normal limits. Chest X-ray was normal. Primary tuberculosis of the parotid gland in a patient with HIV-infection was diagnosed and anti-mycobacterial therapy was started. In HIV-patients with unilateral swelling of the parotid gland, tuberculosis should be considered in the differential diagnosis of pleomorphic adenoma and fine needle aspiration cytology should be performed to avoid unnecessary surgery.

The accuracy of navigation systems can be improved significantly by using high-resolution flat panel-based Volume Computed Tomography (fpVCT) so that new surgical therapeutic concepts become feasible. A navigation-guided minimally-invasive cochleostomy places highest requirements on the accuracy of intraoperative navigation.A flat-panel Volume Computed Tomograph (fpVCT) was used to scan four human temporal bones. The isometric voxel size was 200 microm. The preoperative planning was used to define an optimized drilling channel from the mastoid surface to the round window niche and the scala tympani providing a safety margin to critical anatomical structures such as facial nerve, chorda tympani, sigmoid sinus and posterior wall of auditory canal. The canal was drilled hand-operated with a navigated drill following the previously planned trajectory. Afterwards the drilled canal was imaged by fpVCT. Conventional dissection including mastoidectomy and posterior tympanotomy assured correct localization of the cochleostomy.Path planning took an average of 54 minutes (range 35-85 minutes). Installation took an average of 16 minutes (range 14-19 minutes). The drilling procedure itself took an average of 7.75 min (range 5-12 minutes.) The RMSE-values varied between 0.1 and 0.2 mm (Table 1). All four specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in one specimen--this was preoperatively planned as a narrow facial recess was encountered. The time needed for planning and system-installation could be reduced continuously.This feasibility study demonstrates that using current image-guided surgery technology in combination with fpVCT allows drilling of a minimally invasive channel to the cochlea with loco typico cochleostomy. The necessary accuracy of intraoperative navigation can be achieved by use of fpVCT (technical accuracy between 0.1 and 0.2 mm). Our results demonstrate the feasibility of a navigation-guided minimally-invasive cochleostomy loco typico. While we are enthused by this preliminary work, we recognize the barriers which exist in translation to clinical application. These include surgical issues (e.g. control of unexpected bleeding) and electrode issues (e.g. development of insertion tools).

The efficacy of cochlear implant performance depends, among many other factors, on the number of excitable spiral ganglion cells (SGCs) and the nerve-electrode interface. In earlier animal studies it has been demonstrated that neurotrophic factors are effective to improve SGC survival after experimentally induced deafness. With regard to their anti-inflammatoric and anti-proliferative effects, glucocorticoids (e. g. dexamethasone) are potentially interesting therapeutic agents to reduce connective tissue formation around the inserted electrode. The biological effects of a combined intervention of neurotrophic factors with steroids on SGCs are unknown. Therefore the objective of the study was to investigate possible trophic or even toxic effects of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF) and dexamethasone on neurite outgrowth of cultivated SGCs.By using dissociated postnatal spiral ganglion cells (p3-5) for cultivation in the present study, the influence of the mentioned factors in various concentrations and combinations on neurite outgrowth of SGCs was analysed.Our results indicate significant trophic effects for BDNF (50 ng/ml) and a combination of BDNF with dexamethasone (100 ng/ml) on SGC neurite outgrowth. In contrast, single application of GDNF or dexamethasone in different concentrations caused no significant changes on neurite outgrowth when compared to the control condition.Neurite outgrowth induced by neurotrophic factors could not be observed to be reduced when dexamethasone is given at the same time. Therefore the demonstrated results provide a basis for further animal studies in this field of research.

A 53-year-old patient with myotonic dystrophy presented to our clinic with progressive bilateral hearing loss. The ENT status and particularly the otological examination were without pathological signs. Pure tone audiograms showed a bilateral moderate to severe sensorineural hearing loss. Routinely performed computed tomography of the temporal bones revealed the rare picture of exostosis of the internal auditory canals and the medial surface of the petrous bones. To our knowledge, this is the first report describing exostosis of the internal auditory canal in a patient with myotonic dystrophy, although at present it remains unclear in how far there is a causal connection between these two pathologies.

We present a case of a facial palsy as the initial symptom of a bronchogenic carcinoma.Case-report. A 56-year-old patient presented with a peripheral facial palsy. The clinical picture as well as the temporal bone CT were without pathological findings. A 10-day rheologic therapy as well as anti-viral medication were not successful. Five days after rheological therapy had been completed, the patient presented a swelling of the neck. In the computer tomography we found a bilateral thrombosis of the internal jugular vein. In addition, the clinical picture of a left-sided glossopharyngeal palsy appeared. The following thorax CT as well as the diagnostic extirpation of an enlarged cervical lymph node lead to the diagnosis of a metastasized smallcell neuro-endocrine bronchogenic carcinoma with a compression of the right primary bronchus and the vena cava superior as well as an upper inflow congestion. In the cMRT we furthermore found a metastasis in the area of the foramen stylomastoideum. The patient underwent emergency radiation and chemotherapy.According to the present findings, this metastasis lead to the facial palsy as the initial symptom of the bronchogenic carcinoma.Therefore, therapy resistant facial palsy should be further diagnosed in detail, especially examined by imaging procedures.

We report the case of a 55 year old man with osteomyelitic destruction of the odontoid process and a parapharyngeal abscess. The patient was admitted with diagnosis of meningitis and degenerative cervical spine disease without compression of spinal cord or nerve roots but progressive impairment of cervical spine mobility. Inflammatory parameters in serum and cerebrospinal fluid were detected and antibiotic therapy was initiated resulting in subjective improvement of symptoms. When impairment of cervical spine motility persisted and gait disturbance developed, a parapharyngeal abscess and an osteomyelitic destruction of the odontoid process caused by infection with staphylococcus aureus was diagnosed. After cleavage of the abscess and four months of antibiotic therapy the gait disturbance disappeared and mild impairment of cervical spine motility persisted.

Recent studies have shown that neurotrophic factors like BDNF, NT-3 and GDNF induce protective effects on spiral ganglion cells after noise- or drug-induced hearing loss. According to these studies it is suggested that deafness leads to a lack of neurotrophic factor or relating receptor expression in spiral ganglion cells, that has to be compensated by local cochlear application of these factors.In the present study we examined the expression pattern of members of the GDNF family (GDNF, Neurturin, Artemin, Persephin) and their relating receptors (Ret, GFRalpha1 - 3) as well as BDNF and trkB on spiral ganglion cells of normal hearing and experimentally deafened rats (10 % neomycine). Indirect immunofluorescence was carried out to determine protein expression of these factors and their receptors 26 days following deafening.Our results demonstrate neurotrophic factor and receptor expression on spiral ganglion cells of normal hearing as well as experimentally deafened animals.Our data indicate that within a period of 26 days after deafening no detectable reduction of the GDNF-family member expression and their receptors was ascertainable on spiral ganglion cells by immunohistochemistry. Thus, a lack of neurotrophic factor expression is unlikely to be the only cause of spiral ganglion cell loss following deafening.

A 2(1/2) year old girl was presented with an acute, painless orbital swelling without signs of local or systemic inflammation. CT and MRT scanning revealed a tumor which by open biopsy disclosed embryonal rhabdomyosarcoma. By means of this case we present the current diagnostic and therapeutic approaches for childhood soft tissue sarcomas. At present our patient receives a poly-chemotherapy which has already shown a good response. For local tumor control, a complete surgical resection as well as radiotherapy may be indicated and have to be considered carefully with respect to the possible late effects. This case demonstrates that in a child with a unilateral, progressive orbital tumor, the differential diagnosis of a soft tissue sarcoma has to be ruled out.

The phenotype of deafness and its mechanisms are morphologically and electrophysiologically well characterised. However, the molecular mechanisms and the consequences of deafness are poorly understood.In this study we investigated changes in gene expression profiles in subfractions of the cochlea and the colliculus inferior, a non-cochlear tissue, of normal and deafened (10 % Neomycin) rats using the gene-array-technology. RNA was prepared from modiolus (Mo) und sensorineural epithel/lateral wall (SnE/Lw) und Colliculus inferior (IC), reverse transcribed with gene specific primers, labeled with (32)P-dATP and hybridised with its complementary sequences of 1200 rat ESTs.Similar gene expression profiles were detected in Mo- and SnE/Lw in normal as well in deafened rats differing significantly from those found in IC. In deafened animals differences in mRNA levels were determined in IC for 8 genes, in Mo für 17 genes and in SnE/Lw for 25 genes in comparison to those of normal rats. By using gene-arrays many genes described in the literature previously could be detected. Otherwise most of the genes found in the cochlea are unknown.The gene-array-technology is a valuable tool in otological research for gene expression analysis and, therefore, for comprehensive understanding of molecular processes in the inner ear. Furthermore gene screening for candidate genes could be a big step ahead in developing therapies of diseases of the inner ear.

A 58-year-old patient presented after having undergone radiation therapy, afterloading therapy and chemotherapy of a T4 nasopharynx carcinoma. On the basis of the MRI findings, local tumour recurrence was suspected. The samples taken from the nasopharynx and the left maxillary sinus confirmed this diagnosis. Neuroradiological imaging showed that the tumour extended into the area around the left skull base and also revealed an irregular formation located in the left temporal flap. Therefore not only tumour resection (Fisch approach type C) but also a temporal craniotomy was indicated in order to determine the degree of intracerebral tumour extension. The dura mater, which had been intact, was intraoperatively opened and revealed vital brain tissue, i. e. tumour infiltration had not reached the brain. It was concluded that the radiological findings probably indicated a postradiogenic necrosis of the temporal flap. The presented case illustrates the rare differential diagnostic procedure carried out in a patient with radiogenic necrosis while taking into account the possibility of local tumour infiltration into the brain parenchyma.

Several groups demonstrated in animal experiments that gene transfer is a feasible tool for inner ear intervention. Various approaches for inoculation of vectors have been successfully used for inner ear gene therapy. One possible way to reduce the risk of hearing loss following the opening of the cochlea for application of the vector into the perilymphatic space is to deliver vectors through the round window. This study was designed to determine whether middle ear application of an adenoviral vector is a feasible approach to inoculate vectors and lead to transduction of cells in the inner ear.A unilateral middle ear application of an adenoviral vector was performed in 4 guinea pigs directly on the round window membrane (RWM) and in 4 additional animals by placing a cotton patch soaked with the vector solution on the RWM. The expression of a reporter gene (lacZ) was used to localize vector-transduced cells.Only one out of 8 animals showed cochlear expression of the reporter gene, whereas all 8 animals showed strong lacZ expression in the middle ear mucosa, in the RWM and in the mucosa surrounding the stapes.Our results indicate that the RWM presents a close barrier, almost completely preventing the adenovirus to diffuse into the perilymphatic space. Therefore middle ear application of an adenoviral vector cannot be used to induce inner ear gene transfer. However, middle ear application of a viral vector may be useful for developing treatment for diseases of the middle ear mucosa.