More than two hundred years ago, the Italian Carlo Mondini described the first inner ear malformation (IEM). From that moment, a lot of authors from all over the world put their effort on the discovery, description and classification of IEMs. Anatomists, radiologists and surgeons were involved in this amazing field. But the desire for more information on these anomalies should not be considered ephemeral; a deeper understanding of these pathologies has led over the years to the development of new surgical techniques and approaches for auditory rehabilitation of patients affected by congenital hearing loss. The development of new technologies, in particular in radiology and otolaryngology, had a tremendous impact on the evolution of the classification systems proposed over the decades. The evolution of computed tomography, magnetic resonance imaging (MRI) and cochlear implants is still having a great effect in current clinical management of this kind of patients. Even though so much was obtained over the centuries, we cannot really say that the quest is over. The present review aims to sum up the main historical steps that led to the development of the modern classification systems of IEMs.

Objective: To investigate the prevalence-rate of oval window bulging in the common cavity and its association with bacterial meningitis. Patients: CT and clinical files of 29 children with preliminary diagnosis of common cavity deformity were collected from 13 Italian centers. Intervention: A retrospective case review study was conducted with a centralized evaluation of the temporal bone CT imaging was performed at Azienda Ospedale – Università Padova, Padova, Italy. Main Outcome Measure: Diagnosis of common cavity was reviewed; in addition, a fluid protrusion into the middle-ear cavity through the oval window at CT imaging was considered as oval window bulging. Its association with the history of bacterial meningitis was investigated. Results: Common cavity deformity was confirmed in 14/29 children (mean-age 11.4 ± 3.8; age-range 5–20; nine females) referred with this diagnosis. In 7/14 patients, the common cavity deformity was bilateral (i.e., 21 common cavities). Oval window bulging was found in 3/19 common cavities (concomitant middle-ear effusive otitis hampered the evaluation in two cases), while the internal acoustic meatus fundus was defective in 10/21 cases. History of bacterial meningitis was found in three children (21%) and two of them had oval window bulging at CT. In the case unrelated to oval window bulging, meningitis occurred late at the age of 12 during acute otitis contralateral to common cavity deformity (ipsilaterally to incomplete partition type 1). Conclusion: Patients harboring common cavity deformity have a high risk of meningitis in their first years of life. Oval window bulging seems to be associated with a higher risk of meningitis. This information might be important for appropriate surgical planning.