Laminaria, a hygroscopic seaweed, was used to induce pressure within the rat tympanic cavity. Resorption of the bulla and cochlear walls occurred in all animals within 2 weeks. Cochlear fistulas were observed in four of nine animals after 2 weeks and in nine of 11 aminals after 3 weeks. Preswelled laminaria inserted in the same area induced minimal bone resorption after 2 and 3 weeks. In animals given indomethacin following insertion of laminaria, both granulation-tissue formation and bone resorption were inhibited. Collagenase appeared localized in the inflammatory granulation tissue in the bone-resorption area, especially in fibroblasts, mononuclear cells, and osteoclasts. Results of this study suggested that pressure created by laminaria caused bone resorption by stimulating osteoclasts and granulation tissue.
Abstract During a 2‐year period ending in July 1987, nine patients were implanted with a percutaneous bone‐anchored hearing aid developed at the University of Gothenburg and Chalmers University of Technology, Sweden. Patient selection was based on the presence of conductive or mixed hearing loss in patients who are unable to wear a conventional hearing aid because of infection or ear canal problems. Patients had speech discrimination scores of at least 60% for phonetically balanced monosyllables (CID lists) at 40 dB above threshold, and a pure tone bone conduction average of 45 dB hearing loss or better. Patients were evaluated in sound field, preoperatively and postoperatively using warble tones, speech reception threshold, speech discrimination, and synthetic speech identification. The patient's unaided hearing and hearing with a bone‐anchored hearing aid were compared with the patient's hearing with a standard bone conduction hearing aid. Signal to noise ratio testing with the synthetic speech identification test demonstrated that the bone‐anchored hearing aid was comparable to a standard bone conduction aid. There were no complications in our series. Five patients who reported otorrhea with conventional hearing aids experienced no otorrhea after implantation. Patient satisfaction, as assessed by questionnaire, revealed that all patients preferred the bone‐anchored hearing aid to previously worn hearing aids.
