Background/Purpose: Inflammation of synovial joints in small and large extremities is commonly seen in Rheumatoid arthritis (RA). To date little is known about how this disease affects the synovial, diarthroidal incudomallear (IMJ) located in the middle ear. Previous clinical reports of hearing impairment and altered middle ear impedance in patients with RA have not been substantiated with defined changes along the ossicular chain. Herein, we performed an otopathologic analysis in human specimens with a history of RA during life.

Methods: The National Temporal Bone Registry was queried for cases with history of RA during life. Otopathologic analysis was performed in individuals with RA and compared to age matched controls. Outcomes included descriptive middle ear pathology, volumetric measurements of the IMJ synovial space and immunohistochemical analysis of the IMJ using CD3 and CD20.

Results: Twenty-one ears (specimens) with RA and 18 controls were identified. Mean age was not significantly different between RA and control groups: 65.3 vs 69.3, (p=0.441). In RA and control group females were mainly affected, 75% and 80%, respectively. Middle ear findings in specimens with RA included: IMJ disarticulation, bone erosion of incus and malleus and demineralization of IMJ. These findings were not present in any control specimen. In specimens with RA, diminished spaces between the osseous surfaces in the lateral sides of the ossicles were seen. A loss of total, calcified and hyaline cartilage in lateral and medial sides of the incus was found in RA specimens compared to controls. Diminished synovial space volume of the IMJ was found in RA specimens but not in controls [(2.62 mL (SD 0.49mL) vs 38.4 mL(SD 81.1 mL ), (p=0.004)]. CD3 and CD20 staining was intensely positive within the IMJ space of RA specimens, while controls showed weak IMJ space staining with CD3 and no staining with CD20.

Conclusion: The incudomalleolar joint in patients with RA demonstrate pathologic differences when compared to controls. Cartilage areas and synovial spaces of the RA group were smaller than controls. CD3/CD20 positivity in RA suggests distinct inflammatory involvement of the IMJ. Further study of the functional affects of observed changes on sound transmission is needed.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/rheumatoid-arthritis-affects-the-ossicular-joints-a-human-otopathologic-study/