Item type:Thesis, Open Access

Die toxische Innenohrläsion bei viraler Otitis media mit subakuter Mastoiditis: eine retrospektive Studie zur Therapie und zu CT-morphologischen Merkmalen

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Philipps-Universität Marburg

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Abstract

An acute otitis media can occur because of a viral infection of the upper respiratory tract. A known complication of middle ear inflammation is toxic inner ear damage, where toxic substances from the middle ear effusion enter the labyrinth, causing sensorineural hearing loss. Toxic inner ear damage is more likely to occur in cases of viral otitis media. The round window membrane is predominantly described in the literature as the passage region for a variety of toxic substances. Additionally, there have been discussions about osseous diffusion through weak points in the bony labyrinth, supported by histological studies showing pronounced canal-like structures in the innerear bony structure. Other studies have identified the Fissula ante fenestram as a semi- permeable connection between the middle ear and inner ear. Previous research has also provided initial evidence of a relationship between reduced bone density and the occurrence of toxic inner ear damage. There is currently no specific treatment regimen for acute otitis media with toxic inner ear damage. Despite the prevailing conservative therapy, there are publications in the literature reporting successful surgical treatments. This study compares three conservative therapy regimens and compares conservative therapy with surgical therapy. To gain further insights into anatomical features in this patient population, CT datasets were obtained and examined for differences in bone structure and other anatomical characteristics. Regarding the three conservative therapy regimens, the analysis of individual frequencies revealed only minor differences. Specifically, when comparing the averaged difference values, which should be used as parameters for overall hearing recovery, no statistically significant differences were observed. Nevertheless, all conservative therapy groups showed a significant improvement in inner ear function.In the comparison of surgical and conservative therapy, statistical differences in the course of treatment were identified. In this patient population, surgical treatment was considered a salvage therapy in cases of stagnant hearing recovery in the clinical course. The statistical analysis showed that both groups were initially comparable at the start of treatment. However, the patients later classified in the surgical group experienced a significant decline over time, leading to the decision for mastoidectomy. Subsequently, this group exhibited a significant recovery of hearing ability. As a result, patients in both the conservative and surgical therapy arms achieved comparable results. When comparing the affected petrous bones with those of healthy ear controls, several anatomical abnormalities were identified. The petrous bones with toxic inner ear damage showed significantly reduced pneumatisation. Furthermore, significantly narrower anatomical conditions in the Aditus ad antrum of the affected individuals were observed. A statistically confirmed thinning of bone was found in the course of the lateral semicircular canal. The analysis of Hounsfield units on the labyrinth block revealed significantly lower values at the Fissula ante fenestram and the precochlea, which aligns with the previous assumptions about weak points in this area. This study demonstrated that patients who fail to respond to conservative therapy could experience significant hearing recovery through surgical treatment. However, no significant advantages were found among the investigated conservative therapy regimens. Further research is needed to establish a potential new standard for the treatment of this patient population. The findings of this study regarding the microstructures of the petrous bone in patients with toxic inner ear damage should also prompt further investigations. The role of the canal system, consisting of chondroosseous and Volkmann canals, in the bony labyrinth remains unclear to this day. Speculations have also been made about the specific function of the Fissula ante fenestram. Connections with other ear diseases, such as otosclerosis, remain part of the current discussion.

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Fahr, Lukas: Die toxische Innenohrläsion bei viraler Otitis media mit subakuter Mastoiditis: eine retrospektive Studie zur Therapie und zu CT-morphologischen Merkmalen. : Philipps-Universität Marburg 2025-03-13. DOI: https://doi.org/10.17192/z2024.0306.