Histopathology of residual and recurrent conductive hearing loss after stapedectomy

Hypothesis: Histopathologic examination of temporal bones from patients who had undergone stapedectomy may provide information concerning the causes o f both residual and recurrent conductive hearing loss (CHL). Background: Although closure of the air-bone gap to within 10 dB occurs in approximately 90% of primary stapedectomies, a residual CHL occurs in appro ximately 10% and recurrent CHL may occur in up to 35% of cases. Putative ca uses of failure of surgery as determined during revision include erosion of the incus, bony regrowth at the oval window, and displacement of the prost hesis. Most reports on the histopathologic findings of temporal bones from such patients have focused on complications of surgery, with little attempt to correlate postoperative air-bone gap with the observed histopathology. Methods: A retrospective review of the author's collection of temporal bone s ascertained 22 cases with postoperative CHL of 10 dB or greater (air-bone gap averaged at 500, 1000, 2000, 3000, and 4000 Wt, using postoperative ai r- and bone-conduction levels) after stapedectomy. These temporal bones wer e prepared by standard methodology for light microscopy. Results: Of the 22 cases with postoperative CHL equal to or greater than 10 dB, there were 19 with residual CHL, 2 with recurrent CHL, and 1 with both residual and recurrent CHL. The most common histopathologic correlates of residual and recurrent hearing loss included resorptive osteitis of the inc us (64%); obliteration of the round window by otosclerosis (23%); the prost hesis lying on a residual footplate fragment (23%); the prosthesis abutting the bony margin of the oval window (18%); adhesions in the middle ear (14% ); and new bone formation in the oval window (14%). Conclusions: Histopathologic examination of temporal bones from patients wh o in life had undergone stapedectomy provides useful information concerning causes of both residual and recurrent CHL. These data provide a basis for improving both surgical technique and prosthesis design.