Tissue reaction to prosthetic materials in human temporal bones.

We studied tissue reaction to polymeric silicone (Silastic), polyethylene, tantalum wire, and polytetrafluorethylene (Teflon) in temporal bones and to Silastic in removed shunt tubes. A purpose of this study was to determine which synthetic material is best for insulation of cochlear implant electrodes. We found fibrous tissue around all shunt tubes and in all bones, giant cells in some specimens, and lymphocytic infiltration in a few. We consider none of these findings to indicate bioincompatibility, except in one case with a presumed idiosyncratic reaction to Silastic. We conclude that all four materials are well tolerated by the human ear. Our finding that Silastic is well tolerated for long periods of time leads us to conclude that it is good choice for insulation for implanted wires.

The effect of stapedectomy on hearing of patients with otosclerosis and Meniere's disease.

To determine new guidelines for stapedectomy in patients with both Meniere's disease and otosclerosis, we studied the position of the saccular membrane and Reissner's membrane in relation to the stapes footplate in eight temporal bones from patients with Meniere's disease. We also reviewed charts of four patients with both otosclerosis and Meniere's disease who had stapedectomy. Histologic and clinical findings were compared with preoperative bone conduction levels at 500 Hz and at high frequencies. We found that the saccular and Reissner's membranes did not contact the stapes footplate ain bones of patients with preoperative bone conduction levels of 35 dB or better at 500 Hz and no high-frequency loss. We also found that stapedectomy was successful in patients with the same criteria. We therefore conclude that stapedectomy does not increase the risk of sensorineural hearing loss for patients with otosclerosis and Meniere's disease who have bone conduction levels of 35 dB o better at 500 Hz and no high-tone loss, but it is contraindicated for patients with 45 dB at 500 Hz or worse and with high-tone loss.