2007 ICD-9-CM Procedure 20.6 Fenestration of inner ear A surgical procedure producing an opening from the external auditory canal to the membranous labyrinth, in order to improve conductive hearing loss. The surgical creation of a new opening in the labyrinth of the ear for the restoration of hearing in cases of OTOSCLEROSIS. (Dorland, 27th ed) 20.6 is a non-specific code that should not be used to specify a procedure View the full Volume 3 20.* hierarchy