A novel method to determine standardized anatomic dimensions of the osseous external auditory canal

To introduce a novel method for measuring the dimensions of the osseous external auditory canal (OEAC) on computed tomographic images of the temporal bone.

Radiology case series.

Tertiary care medical center.

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.

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.

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%).

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.