Contemporary Neuroradiographic Assessment of the Cochleo-Carotid Partition

The cochleo-carotid partition (CCP) describes the intimate anatomic relationship between the petrous carotid artery and the cochlear basal turn. This partition bears significant surgical and unique clinical relevance. The purpose of this paper is to radiographically assess the CCP and discuss its clinical implications.

A total of 155 consecutive fine-cut temporal bone CT scans were retrospectively reviewed, and study scans were digitally analyzed in both axial and coronal views. The shortest distance between the petrous carotid canal and the cochlear basal turn was measured.

In all, 310 temporal bones were studied, with a mean CCP of 1.9 mm (range 0.2-8.5, SD 1.1). The following CCP measurements were obtained: ≤1.0 mm [n = 46 (14.8%)]; 1.1-2.0 mm [n = 161 (51.9%)]; 2.1-3.0 mm [n = 29 (9.4%)], and ≥4.0 mm [n = 12 (4.2%)]. One temporal bone (0.3%) had complete CCP dehiscence. There was a positive correlation between each patient's right and left CCP measures (p < 0.005) and a significant negative correlation between CCP grade and age (p = 0.027).

The CCP is a narrow anatomic confinement measuring ≤2 mm in 66.7% of patients. Potential implications of the CCP include iatrogenic risks, its possible function as a third inner ear window in patients with audiovestibular symptoms, and pathophysiology of new-onset tinnitus following cochlear implantation.