External Auditory Canal Erosion at the 6 O’clock Spot

Abstract

Objective To report a common site of external ear canal erosion in multiple pathologies, located inferiorly at 6 o’clock. Patients Otology patients who came in 2023 for treatment of external auditory canal erosions. Intervention This clinical capsule is an observational report of the external canal’s propensity to erosion at the 6 o’clock location. Patient treatments were canalplasty, mastoidectomy, and medical management. Main Outcome Measure Documentation of the propensity to erosion at the 6 o’clock location in the external auditory canal. Locations of the niduses of prior series of external auditory canal pathologies are documented. Results Eight patients are presented with external auditory canal erosion in 10 ears originating at the 6 o’clock position medial to the bony-cartilaginous junction. No other patient with spontaneous canal erosion presented with their nidus of pathology in another canal location. (A review of 42 case series of 291 patients found that keratosis obturans and bisphosphonate-induced osteonecrosis tended to arise from the same 6 o’clock lateral bony canal location, while 26% of necrotizing otitis externa cases arose there.) Conclusions The “6 o’clock spot” in the external canal is a common location of canal erosion for spontaneous wax and keratin collections and may be the precursor to keratosis obturans, bisphosphonate-induced osteonecrosis of the ear canal, and necrotizing otitis externa.