Subcochlear canaliculus patterns in the pediatric and adult population: radiological findings and surgical implications

Introduction: The pneumatization of the different regions of the temporal bone is strictly related to the age and the degree of development of the mastoid and the middle ear. Petrous apex pneumatization is the last step of the development of the petrous bone system. The subcochlear canaliculus is an anatomical cavity, originating in the space between the fustis and the finiculus, and connecting the round window area to the petrous apex. The aim of the present article is analyzing the trend of development of the subcochlear canaliculus pneumatization, classified through CT scan examination, in different age subgroups. Materials and methods: We conducted a retrospective review of patients who underwent temporal bone CT scans between 2014 and 2019. Pediatric and adult patients were included and divided into different age subgroups. The subcochlear canaliculus was examined through coronal view scans at the level of the round window niche and classified into 3 different groups (A, B and C) according to the degree of pneumatization. Results: A total of 270 Petrous bone CT scans was analyzed. The percentage of type A subcochlear canaliculus was significantly higher in the pediatric population if compared to the adult population (p = 0.001326). As far as type B subcochlear canaliculus is concerned, the difference between children and adults was not statistically significant (p = 0.2378). On the other hand, type C subcochlear canaliculus was predominant in the adult population (p = 0.000256). Conclusions: There is a constant increase in pneumatization of the subcochlear canaliculus from 0 to 19 years and then a progressive decrease. This discovery has relevant surgical implications and has to be borne in mind in particular for cholesteatoma surgery and cochlear implantation surgery in the age groups in which the subcochlear canaliculus is highly pneumatized.