Inflammation of the middle ear, known clinically as chronic otitis media, presents in different forms, such as chronic otitis media with effusion (COME; glue ear) and chronic suppurative otitis media (CSOM). These are highly prevalent diseases, especially in childhood, and lead to significant morbidity worldwide. However, much remains unclear about this disease, including its aetiology, initiation and perpetuation, and the relative roles of mucosal and leukocyte biology, pathogens, and Eustachian tube function. Chronic otitis media is commonly modelled in mice but most existing models only partially mimic human disease and many are syndromic. Nevertheless, these models have provided insights into potential disease mechanisms, and have implicated altered immune signalling, mucociliary function and Eustachian tube function as potential predisposing mechanisms. Clinical studies of chronic otitis media have yet to implicate a particular molecular pathway or mechanism, and current human genetic studies are underpowered. We also do not fully understand how existing interventions, such as tympanic membrane repair, work, nor how chronic otitis media spontaneously resolves. This Clinical Puzzle article describes our current knowledge of chronic otitis media and the existing research models for this condition. It also identifies unanswered questions about its pathogenesis and treatment, with the goal of advancing our understanding of this disease to aid the development of novel therapeutic interventions.

People living in low- and middle- income countries (LMICs) meet significant challenges in accessing ear and hearing care (EHC) services. We conducted a scoping review to identify and summarise such barriers, to recognise gaps in the literature, and to identify potential solutions. Reviewers independently screened titles, abstracts and full-text articles and charted data. We undertook thematic analysis of supply and demand side dimensions of access, and summarised findings mapped against the Levesque framework. Of 3048 articles screened, 62 met inclusion criteria for review. Across the five access dimensions, supply-side constraints were more frequently described, the most common being a shortage of EHC workforce or appropriate facilities, despite high demand. We identified a thin geographical spread of literature on barriers to accessing EHC services in LMICs, reflecting low availability of such services. LMICs face a diverse range of demand and supply side challenges including workforce, equipment and resource shortages, and challenges for the majority of the population to pay for such services. There is a need for many LMICs to develop health policy and programmes in EHC, including integration into primary care, scaling up the EHC workforce through increased training and education, and improving EHC literacy through public health measures.