Objective: To introduce a novel method for measuring the dimensions of the osseous external auditory canal (OEAC) on computed tomographic images of the temporal bone.
Study design: Radiology case series.
Setting: Tertiary care medical center.
Patients: A retrospective review of high-resolution computed tomographic images of the temporal bones of 69 patients (120 ears) between the ages of 5 and 85 years (mean, 29.1 yr) was performed.
Main outcome measures: Using a novel method to measure dimensions of the OEAC in the parasagittal planes, 6 defined dimensions as well as length and shape of the OEAC were studied at the annulus, midcanal, and the border of the bony cartilaginous junction.
Results: There was no statistically significant difference in OEAC dimensions between the male and female subjects or patients with and without a history of chronic otitis media within similar age groups. The length of the OEAC was significantly different between age groups of 5 to 12 and older than 13 years. The 6 defined dimensions were statistically different between the age groups of 5 to 8 years and older. These dimensions were not statistically different between the age groups of 9 to 12, 13 to 18, and older than 18 years. The most prevalent shape of the OEAC was conical (64%).
Conclusion: Standardized anatomic dimensions of the OEAC provide important measurements for design of novel in-the-canal hearing aids and specialized earplugs and assist in defining average sizes for canalplasty procedures.