An uncommon “third window” in retrofenestral otosclerosis

Otosclerosis is an otologic disease characterized by disordered resorption and deposition of the otic capsule bone. It can lead to progressive conductive, mixed or sensorineural Hearing Loss (HL). In rare cases, it manifests itself with a tendency for massive bone subsequent formation cavities (“cavitating otosclerosis”). Cavities sometimes realize communication between Cerebrospinal Fluid (CSF) at Internal Auditory Canal (IAC) cochlear duct. these uncommon “third-window” phenomenon may be established as concomitant cause conductive HL. Therefore, feasibility stapes surgery should evaluated, without underestimating risk gusher complications. this report, we discuss case female patient affected cavitating otosclerosis realizing connection IAC duct, hearing loss.